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1.  Annexin A1, A2, A4 and A5 play important roles in breast cancer, pancreatic cancer and laryngeal carcinoma, alone and/or synergistically 
Oncology Letters  2012;5(1):107-112.
Annexins are associated with metastasis and infiltration of cancer cells. Proteomic analysis and immunohistochemical staining were used to understand whether several annexins play important roles in cancer alone and/or synergistically. Seven fresh breast cancer samples with 23 paraffin specimens, three fresh pancreatic samples and five fresh laryngeal carcinoma samples with 25 paraffin specimens were obtained from humans, as well as ten golden hamster pancreatic cancer tissue samples, and they were used to observe differential expression of annexins compared with normal tissues using proteomics and immunohistochemical staining. Annexin A2, A4 and A5 were overexpressed in human breast cancer and laryngeal carcinoma tissues and in golden hamster pancreatic cancer tissue samples, respectively, as shown by proteomics and immunohistochemical staining. In addition, annexin A4 and A5 were expressed in breast cancer tissues, while annexin A1 was not expressed. Annexin A1, A2 and A4 were expressed in human laryngeal carcinoma tissues as shown by immunohistochemical staining. Annexin A1, A2, A4 and A5 played important roles in breast cancer, pancreatic cancer and laryngeal carcinoma, alone and/or synergistically, and they may be targets of therapy for malignant tumors. The choice of which annexins to target should depend on their respective biological behaviors.
PMCID: PMC3525456  PMID: 23255903
breast cancer; pancreatic cancer; laryngeal carcinoma; annexins; proteomics; immunohistochemical staining; overexpression
2.  Nuclear annexin II negatively regulates growth of LNCaP cells and substitution of ser 11 and 25 to glu prevents nucleo-cytoplasmic shuttling of annexin II 
BMC Biochemistry  2003;4:10.
Annexin II heavy chain (also called p36, calpactin I) is lost in prostate cancers and in a majority of prostate intraepithelial neoplasia (PIN). Loss of annexin II heavy chain appears to be specific for prostate cancer since overexpression of annexin II is observed in a majority of human cancers, including pancreatic cancer, breast cancer and brain tumors. Annexin II exists as a heterotetramer in complex with a protein ligand p11 (S100A10), and as a monomer. Diverse cellular functions are proposed for the two forms of annexin II. The monomer is involved in DNA synthesis. A leucine-rich nuclear export signal (NES) in the N-terminus of annexin II regulates its nuclear export by the CRM1-mediated nuclear export pathway. Mutation of the NES sequence results in nuclear retention of annexin II.
Annexin II localized in the nucleus is phosphorylated, and the appearance of nuclear phosphorylated annexin II is cell cycle dependent, indicating that phosphorylation may play a role in nuclear entry, retention or export of annexin II. By exogenous expression of annexin II in the annexin II-null LNCaP cells, we show that wild-type annexin II is excluded from the nucleus, whereas the NES mutant annexin II localizes in both the nucleus and cytoplasm. Nuclear retention of annexin II results in reduced cell proliferation and increased doubling time of cells. Expression of annexin II, both wild type and NES mutant, causes morphological changes of the cells. By site-specific substitution of glutamic acid in the place of serines 11 and 25 in the N-terminus, we show that simultaneous phosphorylation of both serines 11 and 25, but not either one alone, prevents nuclear localization of annexin II.
Our data show that nuclear annexin II is phosphorylated in a cell cycle-dependent manner and that substitution of serines 11 and 25 inhibit nuclear entry of annexin II. Aberrant accumulation of nuclear annexin II retards proliferation of LNCaP cells.
PMCID: PMC200965  PMID: 12962548
3.  Mammary gland neoplasia in long-term rodent studies. 
Environmental Health Perspectives  1996;104(9):938-967.
Breast cancer, the most frequent spontaneous malignancy diagnosed in women in the western world, is continuously increasing in incidence in industrialized nations. Although breast cancer develops in women as the result of a combination of external and endogenous factors such as exposure to ionizing radiation, diet, socioeconomic status, and endocrinologic, familial, or genetic factors, no specific etiologic agent(s) or the mechanisms responsible of the disease has been identified as yet. Thus, experimental models that exhibit the same complex interactions are needed for testing various mechanisms and for assessing the carcinogenic potential of given chemicals. Rodent mammary carcinomas represent such a model to a great extent because, in these species, mammary cancer is a multistep complex process that can be induced by either chemicals, radiation, viruses, or genetic factors. Long-term studies in rodent models have been particularly useful for dissecting the initiation, promotion, and progression steps of carcinogenesis. The susceptibility of the rodent mammary gland to develop neoplasms has made this organ a unique target for testing the carcinogenic potential of specific genotoxic chemicals and environmental agents. Mammary tumors induced by indirect- or direct-acting carcinogens such as 7, 12-dimethlbenz(a)anthracene or N-methyl-N-nitrosourea are, in general, hormone dependent adenocarcinomas whose incidence, number of tumors per animal, tumor latency, and tumor type are influenced by the age, reproductive history, and endocarinologic milieu of the host at the time of carcinogen exposure. Rodent models are informative in the absence of human data. They have provided valuable information on the dose and route of administration to be used and optimal host conditions for eliciting maximal tumorigenic response. Studies of the influence of normal gland development on the pathogenesis of chemically induced mammary carcinomas have clarified the role of differentiation in cancer initiation. Comparative studies with the development of the human breast and the pathogenesis of breast cancer have contributed to validate rodent-to-human extrapolations. However, it has not been definitively established what type of information is necessary for human risk assessment, whether currently toxicity testing methodologies are sufficient for fulfilling those needs, or whether treatment-induced tumorigenic responses in rodents are predictive of potential human risk. An alternative to the traditional bioassays are mechanism-based toxicology and molecular and cellular approaches, combined with comparative in vitro systems. These approaches might allow the rapid screen of chemicals for setting priorities for further studies to determine the dose-response relationship for chemical effects at low doses, to assess effects other than mutagenesis and/or tumorigenesis, or to establish qualitative and quantitative relationships of biomarkers to toxic effects. Until there is enough information on the predictive value of mechanism-based toxicology for risk assessment, this approach should be used in conjunction with and validated by the traditional in vivo long-term bioassays.
PMCID: PMC1469450  PMID: 8899375
4.  Overexpressions of Cyclin B1, cdc2, p16 and p53 in Human Breast Cancer: The Clinicopathologic Correlations and Prognostic Implications 
Yonsei Medical Journal  2011;52(3):445-453.
The molecular mechanisms that are responsible for the initiation and progression of breast cancers are largely unknown. This study was to analyze the cyclin B1, cdc2, p53 and p16 tumor suppressor genes in human breast cancer.
Materials and Methods
To investigate the role of cyclin B1, cdc2, p53 and p16 in the pathogenesis and progression of breast carcinomas, 98 cases of breast cancers were examined by immunohistochemical method. The correlations of cyclin B1, cdc2, p53 and p16 expression with various clinico-pathologic findings were analysed.
In the normal breast tissues, cyclin B1, cdc2 and p16 were weakly expressed, while p53 was not expressed. On the other hand, cyclin B1, cdc2, p53 and p16 were overexpressed in breast cancer, showing correlation between the expression of cyclin B1 and cdc2 and breast cancers (p=0.00). The overexpressions of cdc2 and p16 were correlated with an infiltrative tumor border pattern and this was statistically significant (p<0.05). In addition, the overexpression of cdc2 was correlated with histologic high grade carcinomas (p=0.00).
Cyclin B1 and cdc2 appeared to be involved in the genesis or progression of breast cancers. In addition, the overexpressions of p16 and p53 may play important roles in more aggressive tumor and the overexpression of cdc2 is associated with progression of tumor to a higher grade of breast carcinomas. The deranged overexpressions of cyclin B1, cdc2, p16 and p53 may play an important role in human breast carcinogenesis.
PMCID: PMC3101063  PMID: 21488187
Breast carcinoma; cyclin B1; cdc2; p16; p53; overexpression; prognosis
5.  Implications of tyrosine phosphoproteomics in cervical carcinogenesis 
Worldwide cervical cancer remains a leading cause of mortality from gynecologic malignancies. The link between cervical cancer and persistent infection with HPV has been established. At a molecular level little is known about the transition from the precancerous state to invasive cancer. To elucidate this process, cervical biopsies from human specimens were obtained from precancerous state to stage III disease.
Cervical biopsies were obtained from patients with a diagnosis of cervical cancer undergoing definitive surgery or staging operation. Biopsies were obtained from patients with precancerous lesions at the time of their excisional procedure. Control samples were obtained from patients undergoing hysterectomy for benign conditions such as fibroids. Samples were subjected to proteomic profiling using two dimensional gel electrophoresis with subsequent trypsin digestion followed by MALDI-TOF protein identification. Candidate proteins were then further studied using western blotting, immunoprecipitation and immunohistochemistry.
Annexin A1 and DNA-PKcs were found to be differentially expressed. Phosphorylated annexin A1 was up regulated in diseased states in comparison to control and its level was strongly detected in the serum of cervical cancer patients compared to controls. DNA-PKcs was noted to be hyperphosphorylated and fragmented in cancer when compared to controls. By immunohistochemistry annexin A1 was noted in the vascular environment in cancer and certain precancerous samples.
This study suggests a probable role for protein tyrosine phosphorylation in cervical carcinogenesis. Annexin A1 and DNA-PK cs may have synergistic effects with HPV infection. Precancerous lesions that may progress to cervical cancer may be differentiated from lesions that will not base on similar immunohistochemical profile to invasive squamous cell carcinoma.
PMCID: PMC2483982  PMID: 18637184
6.  Insulin receptor substrate 1 expression enhances the sensitivity of 32D cells to chemotherapy-induced cell death 
Experimental Cell Research  2012;318(14):1745-1758.
The adaptors IRS1 and IRS2 link growth factor receptors to downstream signaling pathways that regulate proliferation and survival. Both suppress factor-withdrawal-induced apoptosis and have been implicated in cancer progression. However, recent studies suggest IRS1 and IRS2 mediate differential functions in cancer pathogenesis. IRS1 promoted breast cancer proliferation, while IRS2 promoted metastasis. The role of IRS1 and IRS2 in controlling cell responses to chemotherapy is unknown. To determine the role of IRS1 and IRS2 in the sensitivity of cells to chemotherapy, we treated 32D cells lacking or expressing IRS proteins with various concentrations of chemotherapeutic agents. We found that expression of IRS1, in contrast to IRS2, enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. When IRS2 was expressed with IRS1, the cells no longer showed enhanced sensitivity. Expression of IRS1 did not alter the expression of pro- and anti-apoptotic proteins; however, 32D-IRS1 cells expressed higher levels of Annexin A2. In 32D-IRS1 cells, IRS1 and Annexin A2 were both located in cytoplasmic and membrane fractions. We also found that IRS1 coprecipitated with Annexin A2, while IRS2 did not. Decreasing Annexin A2 levels reduced 32D-IRS1 cell sensitivity to chemotherapy. These results suggest IRS1 enhances sensitivity to chemotherapy in part through Annexin A2.
PMCID: PMC3395425  PMID: 22652453
insulin receptor substrate; signaling; annexin A2; chemotherapy; cell death
7.  Annexin A2 is regulated by ovarian cancer-peritoneal cell interactions and promotes metastasis 
Oncotarget  2013;4(8):1199-1211.
Our recent research identified the protein annexin A2 to be regulated by ovarian cancer-peritoneal cell interactions. This study investigated the role of annexin A2 in ovarian cancer metastasis and its potential utility as a novel therapeutic target, using in vitro and in vivo ovarian cancer models. Annexin A2 expression was examined by qRT-PCR and western blotting in ovarian cancer cell lines and immunohistochemistry in serous ovarian carcinoma tissues. Annexin A2 siRNAs were used to evaluate the effects of annexin A2 suppression on ovarian cancer cell adhesion, motility, and invasion. Furthermore, annexin A2 neutralizing antibodies were used to examine the role of annexin A2 in tumor invasion and metastasis in vivo using a chick chorioallantoic membrane assay and an intraperitoneal xenograft mouse model. Strong annexin A2 immunostaining was observed in 90% (38/42) of the serous ovarian cancer cells and was significantly increased in the cancer-associated stroma compared to non-malignant ovarian tissues. Annexin A2 siRNA significantly inhibited the motility and invasion of serous ovarian cancer cells and adhesion to the peritoneal cells. Annexin A2 neutralizing antibodies significantly inhibited OV-90 cell motility and invasion in vitro and in vivo using the chick chorioallantoic membrane assay. The growth of SKOV-3 cells and their peritoneal dissemination in nude mice was significantly inhibited by annexin A2 neutralizing antibodies. Annexin A2 plays a critical role in ovarian cancer metastasis and is therefore a potential novel therapeutic target against ovarian cancer.
PMCID: PMC3787151  PMID: 23945256
8.  Breast cancer and human papillomavirus infection: No evidence of HPV etiology of breast cancer in Indian women 
BMC Cancer  2011;11:27.
Two clinically relevant high-risk HPV (HR-HPV) types 16 and 18 are etiologically associated with the development of cervical carcinoma and are also reported to be present in many other carcinomas in extra-genital organ sites. Presence of HPV has been reported in breast carcinoma which is the second most common cancer in India and is showing a fast rising trend in urban population. The two early genes E6 and E7 of HPV type 16 have been shown to immortalize breast epithelial cells in vitro, but the role of HPV infection in breast carcinogenesis is highly controversial. Present study has therefore been undertaken to analyze the prevalence of HPV infection in both breast cancer tissues and blood samples from a large number of Indian women with breast cancer from different geographic regions.
The presence of all mucosal HPVs and the most common high-risk HPV types 16 and 18 DNA was detected by two different PCR methods - (i) conventional PCR assays using consensus primers (MY09/11, or GP5+/GP6+) or HPV16 E6/E7 primers and (ii) highly sensitive Real-Time PCR. A total of 228 biopsies and corresponding 142 blood samples collected prospectively from 252 patients from four different regions of India with significant socio-cultural, ethnic and demographic variations were tested.
All biopsies and blood samples of breast cancer patients tested by PCR methods did not show positivity for HPV DNA sequences in conventional PCRs either by MY09/11 or by GP5+/GP6+/HPV16 E6/E7 primers. Further testing of these samples by real time PCR also failed to detect HPV DNA sequences.
Lack of detection of HPV DNA either in the tumor or in the blood DNA of breast cancer patients by both conventional and real time PCR does not support a role of genital HPV in the pathogenesis of breast cancer in Indian women.
PMCID: PMC3036645  PMID: 21247504
9.  Nuclear localization of Annexin A7 during murine brain development 
BMC Neuroscience  2005;6:25.
Annexin A7 is a member of the annexin protein family, which is characterized by its ability to interact with phospholipids in the presence of Ca2+-ions and which is thought to function in Ca2+-homeostasis. Results from mutant mice showed altered Ca2+-wave propagation in astrocytes. As the appearance and distribution of Annexin A7 during brain development has not been investigated so far, we focused on the distribution of Annexin A7 protein during mouse embryogenesis in the developing central nervous system and in the adult mouse brain.
Annexin A7 is expressed in cells of the developing brain where a change in its subcellular localization from cytoplasm to nucleus was observed. In the adult CNS, the subcellular distribution of Annexin A7 depends on the cell type. By immunohistochemistry analysis Annexin A7 was detected in the cytosol of undifferentiated cells at embryonic days E5–E8. At E11–E15 the protein is still present in the cytosol of cells predominantly located in the ventricular germinative zone surrounding the lateral ventricle. Later on, at embryonic day E16, Annexin A7 in cells of the intermediate and marginal zone of the neopallium translocates to the nucleus. Neuronal cells of all areas in the adult brain present Annexin A7 in the nucleus, whereas glial fibrillary acidic protein (GFAP)-positive astrocytes exhibit both, a cytoplasmic and nuclear staining. The presence of nuclear Annexin A7 was confirmed by extraction of the nucleoplasm from isolated nuclei obtained from neuronal and astroglial cell lines.
We have demonstrated a translocation of Annexin A7 to nuclei of cells in early murine brain development and the presence of Annexin A7 in nuclei of neuronal cells in the adult animal. The role of Annexin A7 in nuclei of differentiating and mature neuronal cells remains elusive.
PMCID: PMC1087847  PMID: 15819996
10.  Annexin A6 contributes to the invasiveness of breast carcinoma cells by influencing the organization and localization of functional focal adhesions 
Experimental cell research  2010;317(6):823-837.
The interaction of annexin A6 (AnxA6) with membrane phospholipids and either specific extracellular matrix (ECM) components or F-actin suggests that it may influence cellular processes associated with rapid plasma membrane reorganization such as cell adhesion and motility. Here, we examined the putative roles of AnxA6 in adhesion-related cellular processes that contribute to breast cancer progression. We show that breast cancer cells secrete annexins via the exosomal pathway and that the secreted annexins are predominantly cell surface-associated. Depletion of AnxA6 in the invasive BT-549 breast cancer cells is accompanied by enhanced anchorage-independent cell growth but cell-cell cohesion, cell adhesion/spreading onto collagen type IV or fetuin-A, cell motility and invasiveness were strongly inhibited. To explain the loss in adhesion/motility, we show that vinculin-based focal adhesions in the AnxA6-depleted BT-549 cells are elongated and randomly distributed. These focal contacts are also functionally defective because the activation of focal adhesion kinase and the phosphoinositide-3 kinase/Akt pathway were strongly inhibited while the MAP kinase pathway remained constitutively active. Compared with normal human breast tissues, reduced AnxA6 expression in breast carcinoma tissues correlates with enhanced cell proliferation. Together this suggests that reduced AnxA6 expression contributes to breast cancer progression by promoting the loss of functional cell-cell and/or cell-ECM contacts and anchorage-independent cell proliferation.
PMCID: PMC3049817  PMID: 21185831
11.  Aberrant Expression of Interleukin-1β and Inflammasome Activation in Human Malignant Gliomas 
PLoS ONE  2014;9(7):e103432.
Glioblastoma is the most frequent and malignant form of primary brain tumor with grave prognosis. Mounting evidence supports that chronic inflammation (such as chronic overactivation of IL-1 system) is a crucial event in carcinogenesis and tumor progression. IL-1 also is an important cytokine with species-dependent regulations and roles in CNS cell activation. While much attention is paid to specific anti-tumor immunity, little is known about the role of chronic inflammation/innate immunity in glioma pathogenesis. In this study, we examined whether human astrocytic cells (including malignant gliomas) can produce IL-1 and its role in glioma progression.
We used a combination of cell culture, real-time PCR, ELISA, western blot, immunocytochemistry, siRNA and plasmid transfection, micro-RNA analysis, angiogenesis (tube formation) assay, and neurotoxicity assay.
Glioblastoma cells produced large quantities of IL-1 when activated, resembling macrophages/microglia. The activation signal was provided by IL-1 but not the pathogenic components LPS or poly IC. Glioblastoma cells were highly sensitive to IL-1 stimulation, suggesting its relevance in vivo. In human astrocytes, IL-1β mRNA was not translated to protein. Plasmid transfection also failed to produce IL-1 protein, suggesting active repression. Suppression of microRNAs that can target IL-1α/β did not induce IL-1 protein. Glioblastoma IL-1β processing occurred by the NLRP3 inflammasome, and ATP and nigericin increased IL-1β processing by upregulating NLRP3 expression, similar to macrophages. RNAi of annexin A2, a protein strongly implicated in glioma progression, prevented IL-1 induction, demonstrating its new role in innate immune activation. IL-1 also activated Stat3, a transcription factor crucial in glioma progression. IL-1 activated glioblastoma-conditioned media enhanced angiogenesis and neurotoxicity.
Our results demonstrate unique, species-dependent immune activation mechanisms involving human astrocytes and astrogliomas. Specifically, the ability to produce IL-1 by glioblastoma cells may confer them a mesenchymal phenotype including increased migratory capacity, unique gene signature and proinflammatory signaling.
PMCID: PMC4108401  PMID: 25054228
12.  Annexin A5 polymorphism (−1C→T) and the presence of anti‐annexin A5 antibodies in the antiphospholipid syndrome 
Annals of the Rheumatic Diseases  2006;65(11):1468-1472.
Annexin A5 is thought to have a role in the pathophysiology of the antiphospholipid syndrome (APS)—a syndrome characterised by recurrent thrombosis and pregnancy morbidity.
To investigate whether anti‐annexin A5 immunoglobulin (Ig)M or IgG antibodies, or the −1C→T polymorphism of annexin A5, is a risk factor for thrombosis or miscarriage, and whether the −1C→T polymorphism is correlated with APS.
A cohort study was carried out with a population of 198 patients with primary APS, systemic lupus erythematosus or lupus‐like disease. For the detection of anti‐annexin A5 antibodies and the measurement of annexin A5 plasma levels, ELISA‐type methods were used. The annexin A5 −1C→T mutation was detected by restriction fragment length polymorphism.
71 patients were positive for annexin A5 IgM or IgG antibodies, of whom 53 patients were positive for anti‐annexin A5 IgG antibodies and 27 of 198 patients were positive for anti‐annexin A5 IgM antibodies. The prevalence of IgM or IgG anti‐annexin A5 antibodies was not significantly associated with thrombosis or miscarriage on multivariate analysis. The prevalence of the −1C→T mutation in the annexin A5 gene (46/198 patients) was significantly associated with miscarriage (odds ratio 2.7, 95% confidence interval 1.1 to 6.7, independent risk factor).
The detection of anti‐annexin A5 antibodies does not seem relevant for estimating the risk for thrombosis or miscarriage in APS. The −1C→T mutation was an independent risk factor for miscarriage, which is independent of APS.
PMCID: PMC1798354  PMID: 16449315
13.  Molecular Characterization of Severin from Clonorchis sinensis Excretory/Secretory Products and Its Potential Anti-apoptotic Role in Hepatocarcinoma PLC Cells 
Clonorchiasis, caused by the infection of Clonorchis sinensis (C. sinensis), is a kind of neglected tropical disease, but it is highly related to cholangiocarcinoma and hepatocellular carcinoma (HCC). It has been well known that the excretory/secretory products of C. sinensis (CsESPs) play key roles in clonorchiasis associated carcinoma. From genome and transcriptome of C. sinensis, we identified one component of CsESPs, severin (Csseverin), which had three putative gelsolin domains. Its homologues are supposed to play a vital role in apoptosis resistance of tumour cell.
Methodology/Principal Findings
There was significant similarity in tertiary structures between human gelsolin and Csseverin by bioinformatics analysis. We identified that Csseverin expressed at life stage of adult worm, metacercaria and egg by the method of quantitative real-time PCR and western blotting. Csseverin distributed in vitellarium and intrauterine eggs of adult worm and tegument of metacercaria by immunofluorence assay. We obtained recombinant Csseverin (rCsseverin) and confirmed that rCsseverin could bind with calciumion in circular dichroism spectrum analysis. It was demonstrated that rCsseverin was of the capability of actin binding by gel overlay assay and immunocytochemistry. Both Annexin V/PI assay and mitochondrial membrane potential assay of human hepatocarcinoma cell line PLC showed apoptosis resistance after incubation with different concentrations of rCsseverin. Morphological analysis, apoptosis-associated changes of mitochondrial membrane potential and Annexin V/PI apoptosis assay showed that co-incubation of PLC cells with rCsseverin in vitro led to an inhibition of apoptosis induced by serum-starved for 24 h.
Collectively, the molecular properties of Csseverin, a molecule of CsESPs, were characterized in our study. rCsseverin could cause obvious apoptotic inhibition in human HCC cell line. Csseverin might exacerbate the process of HCC patients combined with C. sinensis infection.
Author Summary
Clonorchis sinensis (C. sinensis) has afflicted more than 35 million people in world and approximately 15 million in China, creating a socio-economic burden in epidemic regions. The infection of C. sinensis is highly related to cholangiocarcinoma and hepatocellular carcinoma (HCC). It has been documented that excretory/secretory products of C. sinensis (CsESPs) involved in the pathogenesis of HCC. Csseverin, expressed at life stage of egg, metacercaria and adult worm, was a component of CsESPs. In the current study, we characterized the properties of Csseverin such as sequence signature, actin and calciumion binding activity. In addition, we demonstrated that Csseverin could cause apoptotic inhibition in spontaneously apoptotic human HCC cell line PLC cells by using morphological analysis, detection of the apoptosis-associated change of mitochondrial membrane potential (MMP) as well as Annexin V/PI apoptosis assay. Our study provided an exploratory sight view of mechanism involved in progress of carcinoma associated with the infection of C. sinensis and Csseverin might exacerbate the process of C. sinensis infected HCC patients.
PMCID: PMC3868641  PMID: 24367717
14.  Altered expression of estrogen receptor-α variant messenger RNAs between adjacent normal breast and breast tumor tissues 
Breast Cancer Research  1999;2(1):64-72.
Using semiquantitative reverse transcription-polymerase chain reaction assays, we investigated the expression of variant messenger RNAs relative to wild-type estrogen receptor (ER)-α messenger RNA in normal breast tissues and their adjacent matched breast tumor tissues. Higher ER variant truncated after sequences encoding exon 2 of the wild-type ER-α (ERC4) messenger RNA and a lower exon 3 deleted ER-α variant (ERD3) messenger RNA relative expression in the tumor compartment were observed in the ER-positive/PR-positive and the ER-positive subsets, respectively. A significantly higher relative expression of exon 5 deleted ER-α varient (ERD5) messenger RNA was observed in tumor components overall. These data demonstrate that changes in the relative expression of ER-α variant messenger RNAs occur between adjacent normal and neoplastic breast tissues. We suggest that these changes might be involved in the mechanisms that underlie breast tumorigenesis.
Estrogen receptor (ER)-α and ER-β are believed to mediate the action of estradiol in target tissues. Several ER-α and ER-β variant messenger RNAs have been identified in both normal and neoplastic human tissues. Most of these variants contain a deletion of one or more exons of the wild-type (WT) ER messenger RNAs. The putative proteins that are encoded by these variant messenger RNAs would therefore be missing some functional domains of the WT receptors, and might interfere with WT-ER signaling pathways. The detection of ER-α variants in both normal and neoplastic human breast tissues raised the question of their possible role in breast tumorigenesis.
We have previously reported an increased relative expression of exon 5 deleted ER-α variant (ERD5) messenger RNA and of another ER-α variant truncated of all sequences following the exon 2 of the WT ER-α (ERC4) messenger RNA in breast tumor samples versus independent normal breast tissues. In contrast, a decreased relative expression of exon 3 deleted ER-α variant (ERD3) messenger RNA in tumor tissues and cancer cell lines versus independent normal reduction mammoplasty samples has recently been reported. These data were obtained in tissues from different individuals and possible interindividual differences cannot be excluded.
The goal of this study was to investigate the expressions of ERC4, ERD5 and ERD3 variant messenger RNAs in normal breast tissues and their matched adjacent primary breast tumor tissues.
Materials and methods:
Eighteen cases were selected from the Manitoba Breast Tumor Bank, which had well separated and histopathologically characterized normal and adjacent neoplastic components. All tumors were classified as primary invasive ductal carcinomas. Six tumors were ER-negative/progesterone receptor (PR)-negative, nine were ER-positive/PR-positive, two were ER-positive/PR-negative, and one was ER-negative/PR-positive, as measured by ligand-binding assay. For each specimen, total RNA was extracted from frozen normal and tumor tissue sections and was reverse transcribed. The expressions of ERC4, ERD3 and ERD5 messenger RNAs relative to WT ER-α messenger RNA were investigated by previously validated semiquantitative reverse transcription polymerase chain reaction (PCR) assays performed using three different sets of primers.
As shown Figure 1a, two PCR products were obtained that corresponded to WT ER and ERC4 messenger RNAs. For each case, the mean of the ratios obtained in at least three independent PCR experiments is shown for both normal and tumor compartments (Fig 1b). A statistically higher ERC4 messenger RNA relative expression was found in the neoplastic components of ER-positive/PR-positive tumors, as compared with matched adjacent normal tissues (n = 9; P = 0.019, Wilcoxon signed-rank test).
Two PCR products were obtained that corresponded to WT ER and ERD3 messenger RNAs (Fig 2a). A significantly higher expression of ERD3 messenger RNA was observed in the normal compared with the adjacent neoplastic components of ER-positive subset (n =8; P =0.023, Wilcoxon signed-rank test; Fig 2b).
Two PCR products were obtained that corresponded to WT ER and ERD5 complementary DNAs (Fig 3a). As shown in Figure 3b, a statistically significant higher relative expression of ERD5 messenger RNA was observed in tumor components when this expression was measurable in both normal and adjacent tumor tissues (n =15; P =0.035, Wilcoxon signed-rank test).
A statistically significant higher ERC4 messenger RNA expression was found in ER-positive/PR-positive tumors as compared with matched normal breast tissues. ERC4 variant messenger RNA has previously been demonstrated to be more highly expressed in ER-positive tumors that showed poor as opposed to tumors that showed good prognostic characteristics. Interestingly, we also have reported similar levels of expression of ERC4 messenger RNA in primary breast tumors and their concurrent axillary lymph node metastases. Taken together, these data suggest that the putative role of the ERC4 variant might be important at different phases of breast tumorigenesis and tumor progression; alteration of ERC4 messenger RNA expression and resulting modifications in ER signaling pathway probably occur before breast cancer cells acquire the ability to metastasize. Transient expression assays revealed that the protein encoded by ERC4 messenger RNA was unable to activate the transcription of an estrogen-responsive element-reporter gene or to modulate the wild-type ER protein activity. The biologic significance of the changes observed in ERC4 messenger RNA expression during breast tumorigenesis remains to be determined.
A higher relative expression of ERD3 messenger RNA in the normal breast tissue components compared with adjacent neoplastic tissue was found in the ER-positive subgroup. These data are in agreement with the recently published report of Erenburg et al, who showed a decreased relative expression of ERD3 messenger RNA in neoplastic breast tissues compared with independent reduction mammoplasty and breast tumor. Transfection experiments showed that the activation of the transcription of the pS2 gene by estrogen was drastically reduced in the presence of increased ERD3 expression. The authors hypothesized that the reduction in ERD3 expression could be a prerequisite for breast carcinogenesis to proceed.
We observed a significantly higher relative expression of ERD5 messenger RNA in breast tumor components compared with matched adjacent normal breast tissue. These data confirm our previous observations performed on unmatched normal and neoplastic human breast tissues. Upregulated expression of this variant has already been reported in ER-negative/PR-positive tumors, as compared with ER-positive/PR-positive tumors, suggesting a possible correlation between ERD5 messenger RNA expression and breast tumor progression. Even though it has been suggested that ERD5 could be related to the acquisition of insensitivity to antiestrogen treatment (ie tamoxifen), accumulating data refute a general role for ERD5 in hormone-resistant tumors. Only ER-positive pS2-positive tamoxifen-resistant tumors have been shown to express significantly higher levels of ERD5 messenger RNA, as compared with control tumors. Taken together, these data suggest that the exact biologic significance of ERD5 variant expression during breast tumorigenesis and breast cancer progression, if any, remains unclear.
In conclusion, we have shown that the relative expressions of ERC4 and ERD5 variant messenger RNAs were increased in human breast tumor tissue, as compared with normal adjacent tissue, whereas the expression of ERD3 variant messenger RNA was decreased in breast tumor tissues. These results suggest that the expressions of several ER-α variant messenger RNAs are deregulated during human breast tumorigenesis. Further studies are needed to determine whether these changes are transposed at the protein level. Furthermore, the putative role of ER-α variants in the mechanisms that underlie breast tumorigenesis remains to be determined.
PMCID: PMC13912  PMID: 11400682
breast cancer; estrogen receptor; tumorigenesis; variant messenger RNA
15.  Identification, localization, and functional implications of an abundant nematode annexin 
The Journal of Cell Biology  1996;132(6):1079-1092.
Cultures of the nematode C. elegans were examined for the presence of calcium-dependent, phospholipid-binding proteins of the annexin class. A single protein of apparent mass on SDS-polyacrylamide gels of 32 kD was isolated from soluble extracts of nematode cultures on the basis of its ability to bind to phospholipids in a calcium-dependent manner. After verification of the protein as an annexin by peptide sequencing, an antiserum to the protein was prepared and used to isolate a corresponding cDNA from an expression library in phage lambda gt11. The encoded protein, herein referred to as the nex-1 annexin, has a mass of 35 kD and is 36-42% identical in sequence to 10 known mammalian annexins. Several unique modifications were found in the portions of the sequence corresponding to calcium-binding sites. Possible phosphorylation sites in the NH2-terminal domain of the nematode annexin correspond to those of mammalian annexins. The gene for this annexin (nex-1) was physically mapped to chromosome III in the vicinity of the dpy-17 genetic marker. Two other annexin genes (nex-2 and nex-3) were also identified in chromosome III sequences reported by the nematode genomic sequencing project (Sulston, J., Z. Du, K. Thomas, R. Wilson, L. Hillier, R. Staden, N. Halloran, P. Green, J. Thierry-Mieg, L. Qiu, et al. 1992. Nature (Lond.). 356:37-41). The nex-1 annexin was localized in the nematode by immunofluorescence and by electron microscopy using immunogold labeling. The protein is associated with membrane systems of the secretory gland cells of the pharynx, with sites of cuticle formation in the grinder in the pharynx, with yolk granules in oocytes, with the uterine wall and vulva, and with membrane systems in the spermathecal valve. The presence of the annexin in association with the membranes of the spermathecal valve suggests a novel function of the protein in the folding and unfolding of these membranes as eggs pass through the valve. The localizations also indicate roles for the annexin corresponding to those proposed in mammalian systems in membrane trafficking, collagen deposition, and extracellular matrix formation.
PMCID: PMC2120750  PMID: 8601586
16.  Honokiol activates AMP-activated protein kinase in breast cancer cells via an LKB1-dependent pathway and inhibits breast carcinogenesis 
Honokiol, a small-molecule polyphenol isolated from magnolia species, is widely known for its therapeutic potential as an antiinflammatory, antithrombosis, and antioxidant agent, and more recently, for its protective function in the pathogenesis of carcinogenesis. In the present study, we sought to examine the effectiveness of honokiol in inhibiting migration and invasion of breast cancer cells and to elucidate the underlying molecular mechanisms.
Clonogenicity and three-dimensional colony-formation assays were used to examine breast cancer cell growth with honokiol treatment. The effect of honokiol on invasion and migration of breast cancer cells was evaluated by using Matrigel invasion, scratch-migration, spheroid-migration, and electric cell-substrate impedance sensing (ECIS)-based migration assays. Western blot and immunofluorescence analysis were used to examine activation of the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) axis. Isogenic LKB1-knockdown breast cancer cell line pairs were developed. Functional importance of AMPK activation and LKB1 overexpression in the biologic effects of honokiol was examined by using AMPK-null and AMPK-wild type (WT) immortalized mouse embryonic fibroblasts (MEFs) and isogenic LKB1-knockdown cell line pairs. Finally, mouse xenografts, immunohistochemical and Western blot analysis of tumors were used.
Analysis of the underlying molecular mechanisms revealed that honokiol treatment increases AMP-activated protein kinase (AMPK) phosphorylation and activity, as evidenced by increased phosphorylation of the downstream target of AMPK, acetyl-coenzyme A carboxylase (ACC) and inhibition of phosphorylation of p70S6kinase (pS6K) and eukaryotic translation initiation factor 4E binding protein 1 (4EBP1). By using AMPK-null and AMPK-WT (MEFs), we found that AMPK is required for honokiol-mediated modulation of pACC-pS6K. Intriguingly, we discovered that honokiol treatment increased the expression and cytoplasmic translocation of tumor-suppressor LKB1 in breast cancer cells. LKB1 knockdown inhibited honokiol-mediated activation of AMPK and, more important, inhibition of migration and invasion of breast cancer cells. Furthermore, honokiol treatment resulted in inhibition of breast tumorigenesis in vivo. Analysis of tumors showed significant increases in the levels of cytoplasmic LKB1 and phospho-AMPK in honokiol-treated tumors.
Taken together, these data provide the first in vitro and in vivo evidence of the integral role of the LKB1-AMPK axis in honokiol-mediated inhibition of the invasion and migration of breast cancer cells. In conclusion, honokiol treatment could potentially be a rational therapeutic strategy for breast carcinoma.
PMCID: PMC3496153  PMID: 22353783
17.  Methyl Angolensate from Callus of Indian Redwood Induces Cytotoxicity in Human Breast Cancer Cells 
Natural products discovered from medicinal plants have played an important role in the treatment of cancer. Methyl angolensate (MA), a tetranortriterpenoid obtained from the root callus of Indian Redwood tree, Soymida febrifuga Roxb. (A.Juss) was tested for its anticancer properties on breast cancer cells.
Cell viability was tested using trypan blue, MTT and LDH assays. Tritiated thymidine assay and flowcytometry were used to study effect of MA on cell proliferation. The activation of apoptosis was checked by annexin V and JC-1 staining followed by FACS analysis. Immunoblotting analysis was used for studying expression of apoptotic and DNA double strand break repair proteins.
We find that MA inhibited the growth of breast cancer cell line, T47D in a time- and dose-dependent manner. MA treatment led to the inhibition of cell proliferation as detected by tritiated thymidine assay and flowcytometry. Further, MA treated cells exhibited typical apoptotic morphological changes and led to the accumulation of subG1 peak in cell cycle distribution. The induction of apoptosis was further confirmed both by annexin V staining and JC1 staining. We also find that MA activates MAP kinase pathway to induce apoptosis. Besides, we find a time dependent activation followed by degradation of DNA double-strand break repair proteins upon treatment with MA.
These results suggest that MA induces cytotoxicity in breast cancer cells. Further, the altered expression of DSB repair proteins in MA treated cells may control the induction of apoptosis in these cancer cells.
PMCID: PMC3615260  PMID: 23675192
double-strand breaks; intrinsic pathway of apoptosis; cancer therapeutics; alternative medicine; nonhomologous DNA end-joining
18.  Endocytosis occurs independently of annexin VI in human A431 cells 
The Journal of Cell Biology  1994;124(3):301-306.
Annexin VI is one of a family of calcium-dependent phospholipid-binding proteins. Although the function of this protein is not known, various physiological roles have been proposed, including a role in the budding of clathrin-coated pits (Lin et al., 1992. Cell. 70:283-291.). In this study we have investigated a possible endocytotic role for annexin VI in intact cells, using the human squamous carcinoma cell line A431, and report that these cells do not express endogenous annexin VI, as judged by Western and Northern blotting and PCR/Southern blotting. To examine whether endocytosis might in some way be either facilitated or inhibited by the presence of annexin VI, a series of A431 clones were isolated in which annexin VI expression was achieved by stable transfection. These cells expressed annexin VI at similar levels to other human cell types. Using assays for endocytosis and recycling of the transferrin receptor, we report that each of these cellular processes occurs with identical kinetics in both transfected and wild- type A431 cells. In addition, purified annexin VI failed to support the scission of coated pits in permeabilized A431 cells. We conclude that annexin VI is not an essential component of the endocytic pathway, and that in A431 cells, annexin VI fails to exert any influence on internalization and recycling of the transferrin receptor.
PMCID: PMC2119942  PMID: 7905003
19.  Epigenome remodelling in breast cancer: insights from an early in vitro model of carcinogenesis 
Epigenetic gene regulation has influence over a diverse range of cellular functions, including the maintenance of pluripotency, differentiation, and cellular identity, and is deregulated in many diseases, including cancer. Whereas the involvement of epigenetic dysregulation in cancer is well documented, much of the mechanistic detail involved in triggering these changes remains unclear. In the current age of genomics, the development of new sequencing technologies has seen an influx of genomic and epigenomic data and drastic improvements in both resolution and coverage. Studies in cancer cell lines and clinical samples using next-generation sequencing are rapidly delivering spectacular insights into the nature of the cancer genome and epigenome. Despite these improvements in technology, the timing and relationship between genetic and epigenetic changes that occur during the process of carcinogenesis are still unclear. In particular, what changes to the epigenome are playing a driving role during carcinogenesis and what influence the temporal nature of these changes has on cancer progression are not known. Understanding the early epigenetic changes driving breast cancer has the exciting potential to provide a novel set of therapeutic targets or early-disease biomarkers or both. Therefore, it is important to find novel systems that permit the study of initial epigenetic events that potentially occur during the first stages of breast cancer. Non-malignant human mammary epithelial cells (HMECs) provide an exciting in vitro model of very early breast carcinogenesis. When grown in culture, HMECs are able to temporarily escape senescence and acquire a pre-malignant breast cancer-like phenotype (variant HMECs, or vHMECs). Cultured HMECs are composed mainly of cells from the basal breast epithelial layer. Therefore, vHMECs are considered to represent the basal-like subtype of breast cancer. The transition from HMECs to vHMECs in culture recapitulates the epigenomic phenomena that occur during the progression from normal breast to pre-malignancy. Therefore, the HMEC model system provides the unique opportunity to study the very earliest epigenomic aberrations occurring during breast carcinogenesis and can give insight into the sequence of epigenomic events that lead to breast malignancy. This review provides an overview of epigenomic research in breast cancer and discusses in detail the utility of the HMEC model system to discover early epigenomic changes involved in breast carcinogenesis.
PMCID: PMC4053120  PMID: 23168266
20.  The functional and structural characterization of a novel oncogene GIG47 involved in the breast tumorigenesis 
BMC Cancer  2012;12:274.
A candidate oncogene GIG47, previously known as a neudesin with a neurotrophic activity, was identified by applying the differential expression analysis method.
As a first step to understand the molecular role of GIG47, we analyzed the expression profile of GIG47 in multiple human cancers including the breast cancer and characterized its function related to human carcinogenesis. Based on this oncogenic role of GIG47, we then embarked on determining the high-resolution structure of GIG47. We have applied multidimensional heteronuclear NMR methods to GIG47.
GIG47 was over-expressed in primary breast tumors as well as other human tumors including carcinomas of the uterine cervix, malignant lymphoma, colon, lung, skin, and leukemia. To establish its role in the pathogenesis of breast cancer in humans, we generated stable transfectants of MCF7 cells. The ectopic expression of GIG47 in MCF7 cells promoted the invasiveness in the presence of 50% serum. In addition, it also resulted in the increased tumorigenicity in in vivo tumor formation assay. The tumorigenesis mechanism involving GIG47 might be mediated by the activation of MAPK and PI3K pathways. These results indicate that GIG47 plays a role in the breast tumorigenesis, thus representing a novel target for the treatment of breast cancer. To facilitate the development of GIG47-targeted therapeutics, we determined the structural configuration of GIG47. The high-resolution structure of GIG47 was obtained by combination of NMR and homology modeling. The overall structure of GIG47 has four α-helices and 6 β-strands, arranged in a β1-α1-β2-β3-α2-β4-α3-α4-β5-β6 topology. There is a potential heme/steroid binding pocket formed between two helices α2 and α3.
The determined three-dimensional structure of GIG47 may facilitate the development of potential anti-cancer agents.
PMCID: PMC3411491  PMID: 22748190
Breast cancer; Oncogene; GIG47; Three-dimensional structure; Anti-cancer agents
21.  Clinical Significance of Annexin A1 Expression in Breast Cancer 
Journal of Breast Cancer  2011;14(4):262-268.
The expression of Annexin A1 (ANXA1) is known to be reduced in human breast cancer; however, the role of ANXA1 expression in the development of breast cancer remains unclear. In this study, we determined the relationship between the expression features of ANXA1 and the prognostic factors of breast cancer.
Human breast tissues were obtained from patients specimens who had undergone breast surgery or core needle biopsies. The patterns of ANXA1 expression were analyzed by immunohistochemical staining in relation to histopathological diagnosis, clinical characteristics and outcomes.
One hundred eighty-two cases were included and the mean age of the patients was 46.34 ± 11.5 years. A significant loss of ANXA1 expression was noted in both ductal carcinoma in situ (DCIS) and invasive carcinomas compared to normal breast tissues (p<0.001) and benign breast diseases (p<0.001). There was a significant alteration in ANXA1 expression according to hormone receptor status (p<0.001), cancer intrinsic type (p<0.001), and nuclear grade (p=0.004) in invasive cancer. In a univariate analysis, ANXA1 positivity tended to be related with poor breast cancer-related survival (p=0.062); however, the same results was not realized in multivariate results (p=0.406). HER2 overexpression and TNM staging were significantly associated with relapse-free survivals (RFS) in the multivariate analysis (p=0.037, p=0.048, respectively). In particular, in node-positive patients (p=0.048), HER2 overexpressed patients (p=0.013), and non-triple negative breast cancer patients (p=0.002), ANXA1 overexpression was correlated with poor RFS.
Although significant loss of ANXA1 expression was noted in breast cancer including DCIS and invasive carcinoma, in cases of invasive cancer, overexpression of ANXA1 was related to unfavorable prognostic factors. And these results imply that ANXA1 plays dualistic roles and is involved in variable mechanisms related to cancer development and progression.
PMCID: PMC3268921  PMID: 22323911
Annexin A1; Breast neoplasms
22.  Bioinformatics Analysis of Bacterial Annexins – Putative Ancestral Relatives of Eukaryotic Annexins 
PLoS ONE  2014;9(1):e85428.
Annexins are Ca2+-binding, membrane-interacting proteins, widespread among eukaryotes, consisting usually of four structurally similar repeated domains. It is accepted that vertebrate annexins derive from a double genome duplication event. It has been postulated that a single domain annexin, if found, might represent a molecule related to the hypothetical ancestral annexin. The recent discovery of a single-domain annexin in a bacterium, Cytophaga hutchinsonii, apparently confirmed this hypothesis. Here, we present a more complex picture. Using remote sequence similarity detection tools, a survey of bacterial genomes was performed in search of annexin-like proteins. In total, we identified about thirty annexin homologues, including single-domain and multi-domain annexins, in seventeen bacterial species. The thorough search yielded, besides the known annexin homologue from C. hutchinsonii, homologues from the Bacteroidetes/Chlorobi phylum, from Gemmatimonadetes, from beta- and delta-Proteobacteria, and from Actinobacteria. The sequences of bacterial annexins exhibited remote but statistically significant similarity to sequence profiles built of the eukaryotic ones. Some bacterial annexins are equipped with additional, different domains, for example those characteristic for toxins. The variation in bacterial annexin sequences, much wider than that observed in eukaryotes, and different domain architectures suggest that annexins found in bacteria may actually descend from an ancestral bacterial annexin, from which eukaryotic annexins also originate. The hypothesis of an ancient origin of bacterial annexins has to be reconciled with the fact that remarkably few bacterial strains possess annexin genes compared to the thousands of known bacterial genomes and with the patchy, anomalous phylogenetic distribution of bacterial annexins. Thus, a massive annexin gene loss in several bacterial lineages or very divergent evolution would appear a likely explanation. Alternative evolutionary scenarios, involving horizontal gene transfer between bacteria and protozoan eukaryotes, in either direction, appear much less likely. Altogether, current evidence does not allow unequivocal judgement as to the origin of bacterial annexins.
PMCID: PMC3894181  PMID: 24454864
23.  Obesity and Inflammation: New Insights into Breast Cancer Development and Progression 
The importance of inflammation in promoting carcinogenesis and tumor progression is well recognized. Chronic inflammation caused by a variety of infectious agents can lead to the development of several common malignancies. Similarly, inflammatory bowel disease is a well known risk factor for colorectal cancer. Much less is known about the link between inflammation and the development of breast cancer. Recent data suggest that obesity causes both in-breast and systemic inflammation that contribute to the development and progression of breast cancer. This observation has potentially important implications in terms of prevention and treatment of breast cancer, especially given the rising worldwide overweight and obesity rates.
Inflamed white adipose tissue (WAT) within the breast is associated with elevated levels of proinflammatory mediators, enhanced expression of aromatase (the rate-limiting enzyme for estrogen biosynthesis), and increased estrogen receptor-α (ER-α)-dependent gene expression. Systemic consequences of obesity including altered adipokine levels, elevated circulating estrogen levels, and insulin resistance are also believed to play a role in the pathogenesis of breast cancer. Collectively, these findings suggest a significant role for inflammation in the pathogenesis of breast cancer in obese and overweight patients.
PMCID: PMC3897299  PMID: 23714453
24.  Annexin A2: biology and relevance to the antiphospholipid syndrome 
Lupus  2008;17(10):943-951.
Antiphospholipid antibodies (aPL), the majority of which are directed against β2-glycoprotein I (β2GPI), are associated with an increased incidence of venous and arterial thrombosis. The pathogenesis of antiphospholipid/anti-β2GPI-associated thrombosis has not been defined, and is likely multifactorial. However, accumulating evidence suggests an important role for endothelial cell activation with the acquisition of a procoagulant phenotype by the activated endothelial cell. Previous work demonstrated that endothelial activation by antiphospholipid/anti-β2GPI antibodies is β2GPI-dependent. We extended these observations by defining annexin A2 as an endothelial β2GPI binding site. We also observed that annexin A2 plays a critical role in endothelial cell activation induced by anti-β2GPI antibodies, and others have described direct endothelial activation by anti-annexin A2 antibodies in patients with aPL. Similar findings have been reported using human monocytes, which also express annexin A2. Because annexin A2 is not a transmembrane protein, how binding of β2GPI/anti-β2GPI antibodies, or anti-annexin A2 antibodies, to endothelial annexin A2 causes cellular activation is unknown. Recent studies, however, suggest an important role for the Toll-like receptor family, particularly TLR4. In this article, we review the role of these interactions in the activation of endothelial cells by aPL. The influence of these antibodies on the ability of annexin A2 to enhance t-PA-mediated plasminogen activation is also discussed.
PMCID: PMC3417102  PMID: 18827060
annexin; antiphospholipid; β2-glycoprotein I; endothelial; thrombosis
25.  Silencing of TMS1/ASC promotes resistance to anoikis in breast epithelial cells 
Cancer research  2009;69(5):1706-1711.
Ductal carcinoma in situ (DCIS) is characterized by ductal epithelial cells that have filled the luminal space of the breast duct and survive despite loss of extracellular matrix contact. In normal epithelial cells, the loss of such contact triggers a form of apoptosis known as detachment-induced apoptosis or “anoikis.” TMS1/ASC is a bipartite adaptor molecule that participates in inflammatory and apoptotic signaling pathways. Epigenetic silencing of TMS1 has been observed in a significant proportion of human breast and other cancers, but the mechanism by which TMS1 silencing contributes to carcinogenesis is unknown. Here we examined the role of TMS1 in anoikis. We found that TMS1 expression is induced in response to loss of substratum interactions in breast epithelial cells. siRNA-mediated knockdown of TMS1 leads to anoikis resistance, due in part to the persistent activation of ERK and an impaired ability to upregulate the BH3-only protein Bim. We further show that the detachment-induced cleavage of procaspase-8, a newly described mediator of cellular adhesion, is significantly inhibited in the absence of TMS1. These data demonstrate a novel upstream role for TMS1 in the promotion of anoikis, and suggest that silencing of TMS1 may contribute to the pathogenesis of breast cancer by allowing epithelial cells to bypass cell death in the early stages of breast cancer development. This conclusion is supported by in vivo data showing that TMS1 is selectively downregulated in the aberrant epithelial cells filling the lumen of the breast duct in a subset of primary DCIS lesions.
PMCID: PMC2837082  PMID: 19223547
DCIS; breast cancer; apoptosis; caspase-8; Bim

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