GATA3 is a zinc finger transcription factor that regulates the normal development of many tissues and cell types. Recent studies have shown that immunohistochemical nuclear staining for GATA3 among tumors is highly restricted to carcinomas of breast and urothelial origin; however salivary gland tumors have not been tested. Given that breast and salivary gland tissues are very similar with respect to embryologic development and structure, we performed GATA3 staining on a spectrum of salivary gland neoplasms. GATA3 immunohistochemistry was performed on a diverse collection of 180 benign and malignant salivary gland neoplasms including 10 acinic cell carcinomas, 2 adenocarcinomas not otherwise specified, 41 adenoid cystic carcinomas, 2 epithelial-myoepithelial carcinomas, 1 low grade cribriform cystadenocarcinoma, 15 mammary analogue secretory carcinomas, 7 metastatic squamous cell carcinomas, 27 mucoepidermoid carcinomas, 2 oncocytic carcinomas, 5 oncocytomas, 34 pleomorphic adenomas, 4 polymorphous low grade adenocarcinomas, 25 salivary duct carcinomas, and 5 Warthin tumors. Staining for GATA3 was observed in 92/180 (51 %) of salivary gland tumors. GATA3 staining was observed in most of the tumor types, but diffuse immunolabeling was consistently seen in salivary duct carcinoma (25 of 25) and mammary analogue secretory carcinoma (15 of 15)—the two tumor types that most closely resemble breast neoplasia. Background benign salivary gland tissue was also usually weakly positive in both acini and ducts. GATA3 immunostaining is not restricted to tumors of breast and urothelial origin. Rather, it is expressed across many different types of salivary gland neoplasms. As a result, salivary gland origin should be considered in the differential diagnosis of a GATA3-positive carcinoma, particularly in the head and neck. Although GATA3 immunohistochemistry is not helpful in resolving the differential diagnosis between a primary salivary gland neoplasm and metastatic breast cancer, it may have some utility in subtyping salivary gland tumors, particularly salivary duct carcinoma and mammary analogue secretory carcinoma.
GATA3; Immunohistochemistry; Salivary glands; Salivary duct carcinoma; Mammary analogue secretory carcinoma
Urothelial cell carcinoma (UCC) is the second most common genitourinary malignant disease in the USA, and tobacco smoking is the major known risk factor for UCC development. Exposure to carcinogens, such as those contained in tobacco smoke, is known to directly or indirectly damage DNA, causing mutations, chromosomal deletion events and epigenetic alterations in UCC. Molecular studies have shown that chromosome 9 alterations and P53, RAS, RB and PTEN mutations are among the most frequent events in UCC. Recent studies suggested that continuous tobacco carcinogen exposure drives and enhances the selection of epigenetically altered cells in UCC, predominantly in the invasive form of the disease. However, the sequence of molecular events that leads to UCC after exposure to tobacco smoke is not well understood.
To elucidate molecular events that lead to UCC oncogenesis and progression after tobacco exposure, we developed an in vitro cellular model for smoking-induced UCC. SV-40 immortalized normal HUC1 human bladder epithelial cells were continuously exposed to 0.1% cigarette smoke extract (CSE) until transformation occurred. Morphological alterations and increased cell proliferation of non-malignant urothelial cells were observed after 4 months (mo) of treatment with CSE. Anchorage-independent growth assessed by soft agar assay and increase in the migratory and invasive potential was observed in urothelial cells after 6 mo of CSE treatment. By performing a PCR mRNA expression array specific to the PI3K-AKT pathway, we found that 26 genes were upregulated and 22 genes were downregulated after 6 mo of CSE exposure of HUC1 cells. Among the altered genes, PTEN, FOXO1, MAPK1 and PDK1 were downregulated in the transformed cells, while AKT1, AKT2, HRAS, RAC1 were upregulated. Validation by RT-PCR and western blot analysis was then performed. Furthermore, genome-wide methylation analysis revealed MCAM, DCC and HIC1 are hypermethylated in CSE-treated urothelial cells when compared with non-CSE exposed cells. The methylation status of these genes was validated using quantitative methylation-specific PCR (QMSP), confirming an increase in methylation of CSE-treated urothelial cells compared to untreated controls. Therefore, our findings suggest that a tobacco signature could emerge from distinctive patterns of genetic and epigenetic alterations and can be identified using an in vitro cellular model for the development of smoking-induced cancer.
bladder cancer; cigarette smoke extract; epigenetics; in vitro transformation; smoking; urothelial cell carcinoma
To elucidate the role of biological and clinical impact of aberrant promoter hypermethylation (PH) in ovarian cancer (OC).
PH of PGP9.5, HIC1, AIM1, APC, PAK3, MGMT, KIF1A, CCNA1, ESR1, SSBP2, GSTP1, FKBP4 and VGF were assessed by quantitative methylation specific PCR (QMSP) in a training set. We selected two genes (VGF and PGP9.5) for further QMSP analysis in a larger independent validation (IV) set with available clinical data. Biologic relevance of VGF gene was also evaluated.
PH frequency for PGP9.5 and VGF were 85% (316/372) and 43% (158/366) respectively in the IV set of samples while no PH was observed in controls. In 372 OC cases with available follow up, PGP9.5 and VGF PH were correlated with better patient survival [Hazard Ratios (HR) for overall survival (OS) were 0.59 (95% Confidence Intervals (CI) = 0.42–0.84, p = 0.004), and 0.73 (95%CI = 0.55–0.97, p = 0.028) respectively, and for disease specific survival (DSS) were 0.57 (95%CI 0.39–0.82, p = 0.003) and 0.72 (95%CI 0.54–0.96, p = 0.027). In multivariate analysis, VGF PH remained an independent prognostic factor for OS (HR 0.61, 95%CI 0.43–0.86, p<0.005) and DSS (HR 0.58, 95%CI 0.41–0.83, p<0.003). Furthermore, PGP9.5 PH was significantly correlated with lower grade, early stage tumors, and with absence of residual disease. Forced expression of VGF in OC cell lines inhibited cell growth.
Our results indicate that VGF and PGP9.5 PH are potential biomarkers for ovarian carcinoma. Confirmatory cohorts with longitudinal follow-up are required in future studies to define the clinical impact of VGF and PGP9.5 PH before clinical application.
To evaluate the prognostic significance of six epigenetic biomarkers (AIM1, CDH1, KIF1A, MT1G, PAK3 and RBM6 promoter hypermethlation) in a homogeneous group of prostate cancer patients, following radical prostatectomy.
Patients and Methods
Biomarker analyses were performed retrospectively on tumors from 95 prostate cancer patients all with a Gleason score of 3+4=7 and a minimum follow up period of 8 years. Using Quantitative Methylation Specific PCR (QMSP), we analyzed the promoter region of six genes in primary prostate tumor tissues. Time to any progression was the primary endpoint and development of metastatic disease and/or death from prostate cancer was a secondary endpoint. The association of clinicopathological and biomolecular risk factors to recurrence was performed using the Log-rank test and Cox proportional hazards model for multivariate analysis. To identify independent prognostic factors, a stepwise selection method was used.
At a median follow-up time of 10 years, 48 patients (50.5%) had evidence of recurrence: biochemical/PSA relapse, metastases, or death from prostate cancer. In the final multivariate analysis for time to progression, the significant factors were: older age, HR=0.95 (95% CI: 0.91, 1.0) (P=0.03), positive lymph nodes HR=2.11 (95%CI: 1.05, 4.26) (P=0.04) and decreased hypermethylation of AIM1 HR=0.45 (95%CI: 0.2, 1.0) (P=0.05).
Methylation status of AIM1 in the prostate cancer specimen may predict for time to recurrence in Gleason 3+4=7 patients undergoing prostatectomy. These results should be validated in a larger and unselected cohort.
The purpose of this study was to identify key genetic pathways involved in non-small cell lung cancer (NSCLC) and understand their role in tumor progression. We performed a genome wide scanning using paired tumors and corresponding 16 mucosal biopsies from four follow-up lung cancer patients on Affymetrix 250K-NSpI array platform. We found that a single gene SH3GL2 located on human chromosome 9p22 was most frequently deleted in all the tumors and corresponding mucosal biopsies. We further validated the alteration pattern of SH3GL2 in a substantial number of primary NSCLC tumors at DNA and protein level. We also overexpressed wild-type SH3GL2 in three NSCLC cell lines to understand its role in NSCLC progression. Validation in 116 primary NSCLC tumors confirmed frequent loss of heterozygosity of SH3GL2 in overall 51 % (49/97) of the informative cases. We found significantly low (p=0.0015) SH3GL2 protein expression in 71 % (43/60) primary tumors. Forced over-expression of wild-type (wt) SH3GL2 in three NSCLC cell lines resulted in a marked reduction of active epidermal growth factor receptor (EGFR) expression and an increase in EGFR internalization and degradation. Significantly decreased in vitro (p=0.0015–0.030) and in vivo (p=0.016) cellular growth, invasion (p=0.029–0.049), and colony formation (p=0.023–0.039) were also evident in the wt-SH3GL2-transfected cells accompanied by markedly low expression of activated AKT(Ser473), STAT3 (Tyr705), and PI3K. Downregulation of SH3GL2 interactor USP9X and activated β-catenin was also evident in the SH3GL2-transfected cells. Our results indicate that SH3GL2 is frequently deleted in NSCLC and regulates cellular growth and invasion by modulating EGFR function.
Single nucleotide polymorphism array; Lung cancer; SH3GL2; Deletion
Silencing of tumor suppressor genes plays a vital role in head and neck carcinogenesis. Aberrant hypermethylation in the promoter region of some known or putative tumor suppressor genes occurs frequently during the development of various types of cancer including head and neck squamous cell carcinoma (HNSCC). In this study we used an expanded mRNA expression profiling approach followed by microarray expression analysis to identify epigenetically inactivated genes in HNSCC. Two HNSCC cell lines were treated with 5-aza-2′-deoxycytidine followed by microarray analysis to identify epigenetically silenced genes in HNSCC. We found 1,960, 614 and 427 genes were upregulated in the HNSCC cell lines JHU-012, JHU-011 and the combination of both cell lines, respectively. HNSCC tumor and normal mucosal samples were used for gene profiling by a 47K mRNA gene expression array and we found 7,140 genes were downregulated in HNSCC tumors compared to normal mucosa, as determined by microarray analysis, and were integrated with cell line data. Integrative analysis defined 126 candidate genes, of which only seven genes showed differential methylation in tumors and no methylation in normal mucosa after bisulfite sequencing. Following validation by QMSP, one gene, guanine nucleotide-binding protein γ-7 (GNG7), was confirmed to be highly methylated in tumors and unmethylated in normal mucosal and salivary rinse samples demonstrating cancer-specific methylation in HNSCC tissues. TXNIP and TUSC2 were partially methylated in tumors and normal salivary rinses but unmethylated in normal mucosa. We concluded that GNG7 is a highly specific promoter methylated gene associated with HNSCC. In addition, TXNIP and TUSC2 are also potential biomarkers for HNSCC.
guanine nucleotide-binding protein γ-7; gene expression; silencing; head and neck squamous cell carcinoma; epigenetics
We investigated the feasibility of detecting aberrant DNA methylation of some novel and known genes in the serum of lung cancer patients.
To determine the analytical sensitivity, we examined the tumor and the matched serum DNA for aberrant methylation of fifteen gene promoters from 10 patients with primary lung tumors by using Quantitative methylation specific PCR. We then tested this 15 gene set to identify the more useful DNA methylation changes in the serum of a limited number of lung cancer patients and controls. In an independent set, we tested the six most promising genes (APC, CDH1, MGMT, DCC, RASSF1A and AIM) for further elucidation of the diagnostic application of this panel of markers.
Promoter hypermethylation of at least one of the genes studied was detected in all 10 lung primary tumors. In majority of cases, aberrant methylation in serum DNA was accompanied by methylation in the matched tumor samples. In the independent set, using a single gene that had 100% specificity (DCC), 35.5% (95% CI 25%, 47%) of the 76 lung cancer patients were correctly identified. For patients without methylated DCC, addition of a logistic regression score that was based on the five remaining genes improved sensitivity from 35.5% to 75% (95% CI: 64%, 84%) but decreased the specificity from 100% to 73% (95% CI:54%, 88%).
This approach needs to be evaluated in a larger test set to determine the role of this gene set in early detection and surveillance of lung cancer.
DNA methylation/epigenetics; serum; lung cancer
Nasopharyngeal carcinoma (NPC) is a rare malignancy with unique genetic, viral and environmental characteristic that distinguishes it from other head and neck carcinomas. The clinical management of NPC remains challenging largely due to the lack of early detection strategies for this tumor. In the present study we have sought to identify novel genes involved in the pathogenesis of NPC that might provide insight into this tumor's biology and could potentially be used as biomarkers. To identify these genes, we studied the epigenetics of NPC by characterizing a panel of methylation markers. Eighteen genes were evaluated by quantitative methylation-specific PCR in cell lines as well as in tissue samples including 50 NPC tumors and 28 benign nasopharyngeal biopsies. Significance was evaluated using Fisher's exact test and quantitative values were optimized using cut off values derived from receiver-operator characteristic curves. The methylation status of AIM1, APC, CALCA, DCC, DLEC, DLC1, ESR, FHIT, KIF1A, and PGP9.5 was significantly associated with NPC compared to controls. The sensitivity of the individual genes ranged from 26 to 66% and the specificity was above 92% for all genes except FHIT. The combination of PGP9.5, KIF1A, and DLEC had a sensitivity of 84% and a specificity of 92%. Ectopic expression of DCC and DLC1 lead to decrease in colony formation and invasion properties. Our results indicate that methylation of novel biomarkers in NPC could be used to enhance early detection approaches. Additionally, our functional studies reveal previously unknown tumor suppressor roles in NPC.
Strategies to address resistance to platin drugs are greatly needed in human epithelial cancers (e.g. ovarian, head/neck and lung) where platins are used widely and resistance occurs commonly. We found that upon ΔNp63α overexpression, AKT1 and phospho-AKT1 levels are up regulated in cancer cells. Investigations using gel-shift, chromatin immunoprecipitation and functional reporter assays implicated ΔNp63α in positive regulation of AKT1 transcription. Importantly, we found that ΔNp63α, AKT1 and phospho-AKT levels are greater in 2008CI3 CDDP-resistant ovarian cancer cells than in 2008 CDDP-sensitive cells. siRNA-mediated knockdown of ΔNp63α expression dramatically decreased AKT1 expression, whereas knockdown of either ΔNp63α or AKT1 decreased cell proliferation and increased death of ovarian and head/neck cancer cells. Conversely, enforced expression of ΔNp63α increased cancer cell proliferation and reduced apoptosis. Together, our findings define a novel ΔNp63α-dependent regulatory mechanism for AKT1 expression and its role in chemotherapeutic resistance of ovarian and head/neck cancer cells.
ΔNp63α; AKT1; CDDP; chemoresistance
Valosin-containing protein (VCP)/p97 is an AAA ATPase molecular chaperone that regulates vital cellular functions and protein-processing. A recent study indicated that VCP expression levels are correlated with prognosis and progression of non-small cell lung carcinoma (NSCLC). We not only verified these findings but also identified the specific role of VCP in NSCLC pathogenesis and progression.
Our results show that VCP is significantly overexpressed in non-small cell lung carcinoma (NSCLC) as compared to normal tissues and cell lines (p<0.001). Moreover, we observed the corresponding accumulation of ubiquitinated-proteins in NSCLC cell lines and tissues as compared to the normal controls. VCP inhibition by si/shRNA or small-molecule (Eeyarestatin I, EerI) significantly (p<0.05, p<0.00007) suppressed H1299 proliferation and migration but induced (p<0.00001) apoptosis. Cell cycle analysis by flow cytometry verified this data and shows that VCP inhibition significantly (p<0.001, p<0.003) induced cell cycle arrest in the G0/G1 phases. We also found that VCP directly regulates p53 and NFκB protein levels as a potential mechanism to control tumor cell proliferation and progression. Finally, we evaluated the therapeutic potential of VCP inhibition and observed significantly reduced NSCLC tumor growth in both in vitro and xenograft murine (athymic-nude) models after EerI treatment (p<0.05).
Thus, targeting VCP in NSCLC may provide a novel strategy to restore p53 and NFκB levels and ameliorate the growth and tumorigenicity, leading to improved clinical outcomes.
Prognosis for patients with non-small cell lung cancer (NSCLC) is poor. The potential value of modulating EGFR for treatment is reflected by the recent approval of specific drugs that inhibit its activity. Mutations in EGFR were reported in lung cancer and generated interest, once they enable the identification of lung cancers likely to respond to various targeted small molecules.
We tested 3 key genetic and epigenetic alterations (EGFR, RASSF1A, and BRAF) of this pathway on a series of primary NSCLC [Total 111; adenocarcinoma 49, squamous cell carcinoma (SCC) 48 and others 14]. The mutational status of KRAS (and p53) was known for these samples. The purpose of this study was to define the pattern of erbB pathway alterations in NSCLC and to test for associations with clinical parameters.
Five EGFR mutations were identified: 3 in adenocarcinoma (6 %), 1 in SCC (2%) and 1 in adenocarcinoma with bronchoalveolar component tumor (7%). EGFR mutations included 3 in-frame deletions in exon 19 and 2 point mutations in exon 21. Promoter methylation of RASSF1A was detected in 25 of 45 adenocarcinomas and 18 of 46 SCC. Mutations of EGFR, BRAF and KRAS in adenocarcinoma were mutually exclusive and inversely correlated with RASSF1A methylation (p = −0.394; p=0.007). Overall, genetic and/or epigenetic alterations of erbB pathway genes were detected in 80% (39/49) of adenocarcinomas.
Nearly half of primary adenocarcinoma harbor molecular alterations of the erbB pathway. Careful characterization of these alterations and response to anti-EGFR therapies is warranted to determine better and accurate determinants of clinical response.
EGFR mutation; DNA methylation/epigenetics; RASSF1A
Human papillomavirus (HPV) 16 is present in up to 60% of patients with head and neck squamous cell carcinoma (HNSCC) and confers a favorable prognosis in terms of recurrence and mortality. Previous reports demonstrated that HPV-16 DNA can be detected in the initial salivary rinses from these patients. In this study, we assessed the feasibility of post-treatment HPV DNA shed from the oral mucosa as a prognostic marker for persistent/recurrent head and neck cancer. Fresh tumor samples and pre- and post-treatment salivary rinses were collected from 59 patients with HNSCC. HPV-16 E6 and E7 DNA copy number in these samples were quantified by real time PCR. Twenty of 59 patients (33.9%) were HPV-16 positive in their tumors before treatment. Four of 20 HPV tumor positive patients ultimately developed recurrence, and 2 of these 4 patients were HPV-16 positive in surveillance salivary rinses (sensitivity = 50%). Of the 39 (66.1%) HPV-16 negative patients on initial clinical presentation and the 16 HPV-16 positive patients who did not recur, none were HPV-16 positive in salivary rinses after treatment (specificity = 100%). HPV-16 presence in follow-up salivary rinses preceded clinical detection of disease recurrence by an average of 3.5 months. Patients with presence of HPV-16 DNA in surveillance salivary rinses are at significant risk for recurrence. Quantitative measurement of salivary HPV-16 DNA has promise for surveillance and early detection of recurrence.
Human Papilloma Virus (HPV); Head and Neck Squamous Cell Carcinoma (HNSCC); quantitative PCR
MicroRNAs (mirs) are small non-coding RNA molecules (~22 nucleotides) that regulate post-transcriptional gene expression. Currently, there has not been a comprehensive study of their role in primary HNSCC. To determine the role of mirs in head and neck squamous cell carcinoma (HNSCC), we screened for altered microRNA expression in HNSCC primary tissue and cell lines. We then further tested the functional impact of alterations of specific mirs.
An initial screening of 4 primary HNSCC, 4 normal mucosal controls and 4 HNSCC cell lines were analyzed for mature microRNA expression by microarray. Significance was determined using Significance Analysis of Microarrays (SAM). Nine microRNAs were found by SAM to be up-regulated or down-regulated in tumor tissue including mir-21,let-7,18,29c,142-3p,155,146b(over-expressed) and 494(under-expressed). Mir-21 was validated by qRT-PCR.
Functional validation by growth assays was performed, further validating mir-21. Transfection of mir-21 into JHU-011 and JHU-012 cell lines showed a 39% increase in cell growth at 72 hrs relative to controls (p<.05). Transfection of the inhibitor into JHU-O12 cell lines showed a 92% decrease in cell growth relative to controls at 72hrs (p<.05). In addition, flow cytometry analysis of JHU-012 cells 48 hrs after mir-21 inhibitor transfection showed a statistically significantly increase in cytochrome c release and increased apoptosis.
These differentially expressed microRNAs may be of interest as potential novel oncogenes and tumor suppressor genes in HNSCC. Mir-21 is a putative oncogenic microRNA in head and neck cancer.
MicroRNA; HNSCC; Mir-21; Mir-494; Mir; Squamous Cell Cancer
DNA methylation has a role in mediating epigenetic silencing of CpG island genes in cancer and other diseases. Identification of all gene promoters methylated in cancer cells “the cancer methylome” would greatly advance our understanding of gene regulatory networks in tumorigenesis. We previously described a new method of identifying methylated tumor suppressor genes based on pharmacologic unmasking of the promoter region and detection of re-expression on microarray analysis. In this study, we modified and greatly improved the selection of candidates based on new promoter structure algorithm and microarray data generated from 20 cancer cell lines of 5 major cancer types. We identified a set of 200 candidate genes that cluster throughout the genome of which 25 were previously reported as harboring cancer-specific promoter methylation. The remaining 175 genes were tested for promoter methylation by bisulfite sequencing or methylation-specific PCR (MSP). Eighty-two of 175 (47%) genes were found to be methylated in cell lines, and 53 of these 82 genes (65%) were methylated in primary tumor tissues. From these 53 genes, cancer-specific methylation was identified in 28 genes (28 of 53; 53%). Furthermore, we tested 8 of the 28 newly identified cancer-specific methylated genes with quantitative MSP in a panel of 300 primary tumors representing 13 types of cancer. We found cancer-specific methylation of at least one gene with high frequency in all cancer types. Identification of a large number of genes with cancer-specific methylation provides new targets for diagnostic and therapeutic intervention, and opens fertile avenues for basic research in tumor biology.
NKX3.1 is a prostatic tumor suppressor gene located on chromosome 8p. Although most studies have shown that staining for NKX3.1 protein is positive in the majority of primary prostatic adenocarcinomas, it has been shown to be downregulated in many high-grade prostate cancers, and completely lost in the majority of metastatic prostate cancers (eg, in 65% to 78% of lesions). A recent study showed that NKX3.1 staining with a novel antibody was highly sensitive and specific for high-grade prostatic adenocarcinoma when compared with high-grade urothelial carcinoma. This raised the question that this antibody may perform better than earlier used antibodies in metastatic prostate tumors. However, the sensitivity and specificity for prostate carcinomas for this antibody in metastatic lesions was not determined. Although prostate-specific antigen (PSA) and prostatic-specific acid phosphatase (PSAP) are excellent tissue markers of prostate cancer, at times they may be expressed at low levels, focally, or not at all in poorly differentiated primary and metastatic prostatic adenocarcinomas. The purpose of this study was to determine the performance of NKX3.1 as a marker of metastatic adenocarcinoma of prostatic origin. Immunohistochemical staining against NKX3.1, PSA, and PSAP was carried out on a tissue microarray (TMA) (0.6-mm tissue cores) of hormone naïve metastatic prostate adenocarcinoma specimens from lymph nodes, bone, and soft tissue. To determine the specificity of NKX3.1 for prostatic adenocarcinoma, we used TMAs that contained cancers from various sites including the urinary bladder, breast, colon, salivary gland, stomach, pancreas, thyroid, and central nervous system, and standard paraffin sections of cancers from other sites including the adrenal cortex, kidney, liver, lung, and testis. Overall 349 nonprostatic tumors were evaluated. Any nuclear staining for NKX3.1 was considered positive and the percentage of cells with nuclear staining and their mean intensity level were assessed visually. Sensitivity was calculated by considering a case positive if any TMA core was positive. The sensitivity for identifying metastatic prostatic adenocarcinomas overall was 98.6% (68/69 cases positive) for NKX3.1, 94.2% (65/69 cores positive) for PSA, and 98.6% (68/69 cores positive) for PSAP. The specificity of NKX3.1 was 99.7% (1/349 nonprostatic tumors positive). The sole positive nonprostatic cancer case was an invasive lobular carcinoma of the breast. NKX3.1 seems to be a highly sensitive and specific tissue marker of metastatic prostatic adenocarcinoma. In the appropriate clinical setting, the addition of IHC staining for NKX3.1, along with other prostate-restricted markers, may prove to be a valuable adjunct to definitively determine prostatic origin in poorly differentiated metastatic carcinomas.
NKX3.1 protein; metastatic prostatic carcinoma; immunohistochemistry
Many risk factors have been associated with cancer, such as age, family history, race, smoking, high-fat diet, and poor nutrition. It is important to reveal the molecular changes related to risk factors that could facilitate early detection, prevention, and overall control of cancer.
We selected six cancer-specific methylated genes that have previously been reported in primary tumors and have also been detected in different bodily fluids of cancer patients. Here, we used quantitative fluorogenic real-time methylation-specific PCR in plasma DNA samples for the detection of methylation changes from an asymptomatic population who do not have any known cancer.
The promoter methylation frequencies of the studied genes were as follows: APC (7%), CCND2 (22%), GSTP1 (2%), MGMT (9%), RARβ2 (29%), and P16 (3%). Promoter methylation of at least one of the genes analyzed was observed in ~46% (72 of 157) of the samples by binary dichotomization. Promoter hypermethylation of at least two genes was detected in 17% (26 of 157) of the samples. RARβ2 methylation was observed in 45% of subjects who had a high-fat diet in contrast with those who had a low-fat diet (23%; P = 0.007).
Our findings may help to elucidate early methylation changes that may lead to cancer development. These methylation changes could be due to exposure to risk factors and may be useful for cancer prevention measures such as changes in lifestyle. Longitudinal follow-up of a high-risk population is needed to understand the association of methylation of candidate genes in cancer development.
We evaluated promoter hypermethylation of a panel of tumor suppressor genes as a means to detect epigenetic alterations in oral squamous cell carcinomas (OSCC) of Indian-origin and compare with North-American head and neck squamous cell carcinomas (HNSCC). Quantitative-methylation-specific PCR was used to investigate the promoter methylation status of DCC, EDNRB, p16INK4a and KIF1A in 92 OSCC, and compared to 48 paired normal tissues and 30 saliva and sera samples from healthy control subjects. Aberrant methylation of at-least one of these genes was detected in 74/92 (80.4%) OSCC; 72.8% at EDNRB, 71.7% at KIF1A, 47.8% at p16INK4a and 58.7% at DCC; and in 5 of 48 (10.4%) normal oral tissues. None of the saliva and sera samples from controls exhibited DNA methylation in these four target genes. Thirty-two of 72 node positive cases harbored p16INK4a and DCC hypermethylation (p = 0.005). Thus, promoter hypermethylation in genes analyzed herein is a common event in Indian OSCC and may represent promising markers for the molecular staging of OSCC patients. We found higher frequency of p16INK4a methylation (47.8%) in this Indian cohort in comparison with a North-American cohort (37.5%). In conclusion, aberrant methylation of EDNRB, KIF1A, DCC and p16INK4a genes is a common event in Indian OSCC, suggesting that epigenetic alterations of these genes warrant validation in larger studies for their potential use as biomarkers.
hypermethylation; EDNRB; KIF1A; OSCC; p16INK4a; DCC; nodal metastasis
Basal-like carcinomas (BLCs) of the breast share discriminatory morphologic features with poorly differentiated high-risk human papilloma virus (HPV)-related squamous cell carcinomas of the oropharynx, penis, and vulva. Because HPV E7 protein inactivates the retinoblastoma (Rb) protein, diffuse p16 expression is a surrogate marker for these high-risk HPV-related carcinomas. HPV E6 protein also inactivates p53, further compromising the G1-S cell cycle checkpoint. The Rb/p16/p53 immunohistochemical profile of BLC of the breast has not been well characterized. Tissue microarrays containing 71 invasive ductal carcinomas (IDCs) of the breast were immunolabeled for p16, Rb, p53, and Ki-67. The cases included 4 distinct groups of IDCs having surrogate immunohistochemical profiles corresponding to categories defined by gene expression profiling (17 luminal A, 7 luminal B, 14 HER-2+, and 21 BLC), along with 12 unclassifiable triple negative carcinomas (UTNCs). Twenty-five of the 71 IDC were Rb negative/p16 diffuse positive (Rb −/p16+). These included 15 of 21 BLC and 9 of 12 UTNC, but only 1 of 14 HER-2 positive cases and none of the 17 luminal A or 7 luminal B cases (P < 0.01, BLC or UTNC vs. others). Six of the Rb − /p16+ IDC also had a significant ductal carcinoma in situ component. The ductal carcinoma in situ in 4 of these 6 cases showed the same Rb − /p16+ phenotype as the associated IDC. BLC and UTNC had the highest Ki-67 indices of the 5 groups, even when matched for grade. The Rb − /p16+ phenotype and the Rb − /p16+/p53 overexpressing phenotype correlated with increased proliferation within the BLC group. In conclusion, BLC and UTNC, but not HER-2, luminal A, or luminal B carcinomas, frequently demonstrate an Rb − /p16+ phenotype, similar to the HPV-related squamous cell carcinomas that BLC resemble morphologically. This subset may represent a more homogenous group than BLC as defined currently.
breast; carcinoma; basal-like; retinoblastoma; p16
This study aimed to test the hypothesis that elevated expression of antiapoptotic Bcl-2 family proteins predicts a poor therapeutic response of oropharyngeal squamous cell carcinoma (OPSCC) to concurrent platinum-based chemoradiation therapy.
Levels of Bcl-2, Bcl-XL, and Bcl-w were determined and correlated with resistance to cisplatin in a large panel of cell lines derived from squamous cell carcinoma of the head and neck (HNSCC). Univariate and multivariate analyses were used to evaluate the relationship between Bcl-2 and Bcl-XL expression and disease-free survival following chemoradiation therapy in a uniformly treated cohort of patients with OPSCC.
In HNSCC cell lines, high endogenous Bcl-2 expression was associated with increased cisplatin resistance, and experimental overexpression of Bcl-2 promoted cisplatin resistance. In patients, tumors positive for Bcl-2 before treatment had greater risk of treatment failure (hazard ratio, 5.99; 95% confidence interval, 1.73−20.8; P = 0.0014). In contrast, endogenous Bcl-XL showed no correlation either with cisplatin sensitivity in the cell line panel in vitro, or with risk of recurrence in vivo (hazard ratio, 1.28; 95% confidence interval, 0.39 − 4.19; P = 0.68). Associations between Bcl-2 expression and other clinical characteristics did not account for the predictive value of Bcl-2.
Immunohistochemical assessment of Bcl-2 in pretreatment biopsy specimens can predict response of advanced OPSCC to concurrent platinum-based chemoradiation. As treatments targeting Bcl-2 and its family members become available, this immunohistochemical assessment could help personalize therapy by identifying a subpopulation of patients with a poor prognosis who might benefit from such treatments.
Cancer/testis antigens (CTAs) were first discovered as immunogenic targets normally expressed in germline cells, but differentially expressed in a variety of human cancers. In this study, we used an integrative epigenetic screening approach to identify coordinately expressed genes in human non-small cell lung cancer (NSCLC) whose transcription is driven by promoter demethylation.
Our screening approach found 290 significant genes from the over 47,000 transcripts incorporated in the Affymetrix Human Genome U133 Plus 2.0 expression array. Of the top 55 candidates, 10 showed both differential overexpression and promoter region hypomethylation in NSCLC. Surprisingly, 6 of the 10 genes discovered by this approach were CTAs. Using a separate cohort of primary tumor and normal tissue, we validated NSCLC promoter hypomethylation and increased expression by quantitative RT-PCR for all 10 genes. We noted significant, coordinated coexpression of multiple target genes, as well as coordinated promoter demethylation, in a large set of individual tumors that was associated with the SCC subtype of NSCLC. In addition, we identified 2 novel target genes that exhibited growth-promoting effects in multiple cell lines.
Coordinated promoter demethylation in NSCLC is associated with aberrant expression of CTAs and potential, novel candidate protooncogenes that can be identified using integrative discovery techniques. These findings have significant implications for discovery of novel CTAs and CT antigen directed immunotherapy.
The aims of our study were to elucidate the role of methylation of a large panel of genes during multistage pathogenesis of bladder cancer and to correlate our findings with patient age and other clinicopathologic features.
We studied the methylation status of 21 genes by quantitative methylation-specific PCR in an evaluation set of 25 tumor and 5 normal samples. Based on methylation frequency in tumors and normals in gene evaluation set, we selected 7 candidate genes and tested an independent set of 93 tumors and 26 normals. The presence or absence of methylation was evaluated for an association with cancer using cross-tabulations and χ2 or Fisher’s exact tests as appropriate. All statistical tests were two-sided.
Most primary tumors (89 of 93, 96%) had methylation of one or more genes of independent set; 53 (57%) CCNA1, 29 (31%) MINT1, 36 (39%) CRBP, 53 (57%) CCND2, 66 (71%) PGP9.5, 60 (65%) CALCA, and 78 (84%) AIM1. Normal uroepithelium samples from 26 controls revealed no methylation of the CCNA1 and MINT1 genes, whereas methylation of CRBP, CCND2, PGP9.5, and CALCA was detected at low levels. All the 7 genes in independent set were tightly correlated with each other and 3 of these genes showed increased methylation frequencies in bladder cancer with increasing age. PGP9.5 and AIM1 methylation correlated with primary tumor invasion.
Our results indicate that the methylation profile of novel genes in bladder cancers correlates with clinicopathologic features of poor prognosis and is an age-related phenomenon.
Tissue inhibitor of metalloproteinases-3 (TIMP-3) is one of four members of a family of proteins that were originally classified according to their ability to inhibit matrix metalloproteinases (MMP). We analyzed TIMP-3 methylation in 175 urine sediment DNA samples from bladder cancer patients with well characterized clinicopathological parameters including patient outcome.
Materials and methods
We examined urine sediment DNA for aberrant methylation of 9 genes including TIMP-3 by quantitative fluorogenic real-time PCR.
Using an optimal cutoff value by Taqman quantitation, we found that the risk of death was statistically significantly higher in patients with higher TIMP-3 and ARF methylation (hazard ratio [HR] =1.99, 95% confidence interval [CI] =1.12 to 3.27; p= 0.01 and HR=1.66, 95% CI=1.00 to 2.76; p=0.05 respectively) than in patients without/lower TIMP3 and ARF methylation in urine. A significant correlation was also seen between risk of death and stage 3 tumor (HR=2.73, 95% CI=1.58 to 4.72; p=0.003 and the presence of metastasis (HR=3.32, 95% CI=1.98 to 5.57; p=0.0001). Multivariate analysis subsequently revealed that TIMP-3 methylation was an independent prognostic factor for bladder cancer survival with stage and metastasis (p=0.001 and 0.02 respectively).
These results suggest that TIMP-3 promoter methylation could be a clinically applicable marker for bladder cancer progression.
Epigenetic alterations have been implicated in the pathogenesis of solid tumors, however, proto-oncogenes activated by promoter demethylation have been sporadically reported. We used an integrative method to analyze expression in primary head and neck squamous cell carcinoma (HNSCC) and pharmacologically demethylated cell lines to identify aberrantly demethylated and expressed candidate proto-oncogenes and cancer testes antigens in HNSCC.
We noted coordinated promoter demethylation and simultaneous transcriptional upregulation of proto-oncogene candidates with promoter homology, and phylogenetic footprinting of these promoters demonstrated potential recognition sites for the transcription factor BORIS. Aberrant BORIS expression correlated with upregulation of candidate proto-oncogenes in multiple human malignancies including primary non-small cell lung cancers and HNSCC, induced coordinated proto-oncogene specific promoter demethylation and expression in non-tumorigenic cells, and transformed NIH3T3 cells.
Coordinated, epigenetic unmasking of multiple genes with growth promoting activity occurs in aerodigestive cancers, and BORIS is implicated in the coordinated promoter demethylation and reactivation of epigenetically silenced genes in human cancers.