Ribonucleotide reductase catalyzes the conversion of ribonucleotide diphosphates to deoxyribonucleotide diphosphates. The functional enzyme consists of two subunits - one large (RRM1) and one small (RRM2 or RRM2b) subunit. Expression levels of each subunit have been implicated in prognostic outcomes in several different types of cancers.
Immunohistochemistry for RRM1 and RRM2 was performed on a lung cancer tissue microarray (TMA) and analyzed. 326 patients from the microarray were included in this study.
In non-small cell lung cancer (NSCLC), RRM2 expression was strongly predictive of disease-specific survival in women, non-smokers and former smokers who had quit at least 10 years prior to being diagnosed with lung cancer. Higher expression was associated with worse survival. This was not the case for men, current smokers and those who had stopped smoking for shorter periods of time. RRM1 was not predictive of survival outcomes in any subset of the patient group.
RRM2, but not RRM1, is a useful predictor of survival outcome in certain subsets of NSCLC patients.
Despite significant advances in biology and medicine, the incidence and mortality due to breast cancer world-wide is still unacceptably high. Thus, there is an urgent need to discover new molecular targets. In this paper, we show evidence for a novel target in human breast cancer, the tetraspan protein epithelial membrane protein-2 (EMP2). Using tissue tumor arrays, protein expression of EMP2 was measured and found to be minimal in normal mammary tissue, but it was upregulated in 63% of invasive breast cancer tumors and in 73% of triple negative tumors tested. To test the hypothesis that EMP2 may be a suitable target for therapy, we constructed a fully human IgG1 antibody specific for a conserved domain of human and murine EMP2. Treatment of breast cancer cells with the anti-EMP2 IgG1 significantly inhibited EMP2 mediated signaling, blocked FAK/Src signaling, inhibited invasion, and promoted apoptosis in vitro. In both human xenograft and syngeneic metastatic tumor monotherapy models, anti-EMP2 IgG1 retarded tumor growth without detectable systemic toxicity. This anti-tumor effect was in part attributable to a potent ADCC response as well as direct cytotoxicity induced by the monoclonal antibody. Together, these results identify EMP2 as a novel therapeutic target for invasive breast cancer.
Epithelial membrane protein-2; breast cancer; triple negative breast cancer; antibody therapy; recombinant IgG1; tumor xenograft
Triple-negative breast cancer (TNBC) occurs in 10–15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated
with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERβ, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERβ expression, we find that ERβ1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERβ protein. To assess ERβ effects on proliferation, ERβ expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERβ-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERβ may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2), along with ERβ1, is significantly expressed in TNBC and stimulates high ERβ mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.
Thyroid transcription factor-1 (TTF-1) is a DNA-binding protein that is mainly expressed in thyroid and lung tissue, but has also been found in gynecologic tissue. Recent studies have suggested that TTF-1 has tumor suppressor function in lung adenocarcinoma models. In the current study, we examined whether expression of TTF-1 in benign endometrium and endometrial hyperplasia might impact on the risk of developing endometrial cancer. Formalin fixed paraffin embedded endometrial tissues obtained from 535 cases were used to construct an endometrial tissue microarray. One-hundred fifty of 207 patients had multiple serial endometrial specimens including 46 patients who progressed to endometrial cancer. The tissue microarray included a range of histopathologies including benign endometrium (n=231), simple hyperplasia (n=105), complex hyperplasia (n=36), simple atypical hyperplasia (n=10), complex atypical hyperplasia (n=44), and endometrial carcinoma (n=109). Expression of TTF-1 by immunohistochemistry in benign endometrium and endometrial hyperplasia was correlated with progression to cancer and clinical features known to be associated with increased risk of developing endometrial cancer. Carcinoma specimens showed a significantly greater expression of TTF-1 compared to benign endometrium and non-atypical hyperplasia (p=0.0007 and p=0.05). Presence of TTF-1 expression in benign endometrium was associated with a significantly decreased risk of cancer development (p=0.003, hazards ratio=0.104, 95% CI 0.024-0.455). TTF-1 expression in hyperplasia did not significantly correlate with progression to cancer. The data from our study shows that TTF-1 expression in normal endometrium is associated with a reduced risk of endometrial cancer development. This observation suggests that TTF-1 might function as a tumor suppressor in endometrial tissue. TTF-1 expression in normal endometrium could potentially provide clinically useful information as a biomarker for the risk of endometrial cancer.
TTF-1; normal endometrium; endometrial hyperplasia; endometrial cancer; immunohistochemistry
The combination of expression patterns of AGR2 and CD10 by prostate cancer provided four phenotypes that correlated with clinical outcome. Based on immunophenotyping, CD10lowAGR2high, CD10highAGR2high, CD10lowAGR2low, and CD10highAGR2low were distinguished. AGR2+ tumors were associated with longer recurrence-free survival and CD10+ tumors with shorter recurrence-free survival. In high-stage cases, the CD10lowAGR2high phenotype was associated with a 9-fold higher recurrence-free survival than the CD10highAGR2low phenotype. The CD10highAGR2high and CD10lowAGR2low phenotypes were intermediate. The CD10highAGR2low phenotype was most frequent in high-grade primary tumors. Conversely, bone and other soft tissue metastases, and derivative xenografts, expressed more AGR2 and less CD10. AGR2 protein was readily detected in tumor metastases. The CD10highAGR2low phenotype in primary tumors is predictive of poor outcome; however, the CD10lowAGR2high phenotype is more common in metastases. It appears that AGR2 has a protective function in primary tumors but may have a role in the distal spread of tumor cells.
Prostate cancer; AGR2; CD10; cancer cell phenotypes; patient stratification; bone and soft tissue metastases; xenografts
Lung cancer is the leading cause of cancer-related deaths in both men and women worldwide. Despite advances in treatment, patients have few effective therapeutic options and survival rates remain low. Emerging evidence suggests that the hormones estrogen and progesterone play a key role in the progression of non-small-cell lung cancer (NSCLC). The aromatase enzyme, which is responsible for a key step in estrogen biosynthesis, elicits higher levels of estrogen in lung tumors as well as in metastases compared with nonmalignant tissues. Thus, aromatase may prove to be a key predictive biomarker for treatment of NSCLC. Epidemiologic and preclinical data show estrogens play a critical role in lung tumor development and progression. Two estrogen receptors, α and β, are expressed in normal and in cancerous lung epithelium, and estrogen promotes gene transcription that stimulates cell proliferation and inhibits cell death. Furthermore, expression of both forms of estrogen receptor, progesterone receptor and aromatase in NSCLC specimens has been correlated with worse clinical outcomes. Combination therapies that include estrogen receptor downregulators and aromatase inhibitors are currently being assessed in Phase I–II clinical trials among patients with advanced NSCLC. Results will help guide future lung cancer management decisions, with a goal of achieving more effective and less toxic treatments for patients.
New biomarkers are needed to detect pleural mesothelioma at an earlier stage and to individualize treatment strategies. We investigated whether fibulin-3 in plasma and pleural effusions could meet sensitivity and specificity criteria for a robust biomarker.
We measured fibulin-3 levels in plasma (from 92 patients with mesothelioma, 136 asbestos-exposed persons without cancer, 93 patients with effusions not due to mesothelioma, and 43 healthy controls), effusions (from 74 patients with mesothelioma, 39 with benign effusions, and 54 with malignant effusions not due to mesothelioma), or both. A blinded validation was subsequently performed. Tumor tissue was examined for fibulin-3 by immunohistochemical analysis, and levels of fibulin-3 in plasma and effusions were measured with an enzyme-linked immunosorbent assay.
Plasma fibulin-3 levels did not vary according to age, sex, duration of asbestos exposure, or degree of radiographic changes and were significantly higher in patients with pleural mesothelioma (105±7 ng per milliliter in the Detroit cohort and 113±8 ng per milliliter in the New York cohort) than in asbestos-exposed persons without mesothelioma (14±1 ng per milliliter and 24±1 ng per milliliter, respectively; P<0.001). Effusion fibulin-3 levels were significantly higher in patients with pleural mesothelioma (694±37 ng per milliliter in the Detroit cohort and 636±92 ng per milliliter in the New York cohort) than in patients with effusions not due to mesothelioma (212±25 and 151±23 ng per milliliter, respectively; P<0.001). Fibulin-3 preferentially stained tumor cells in 26 of 26 samples. In an overall comparison of patients with and those without mesothelioma, the receiver-operating-characteristic curve for plasma fibulin-3 levels had a sensitivity of 96.7% and a specificity of 95.5% at a cutoff value of 52.8 ng of fibulin-3 per milliliter. In a comparison of patients with early-stage mesothelioma with asbestos-exposed persons, the sensitivity was 100% and the specificity was 94.1% at a cutoff value of 46.0 ng of fibulin-3 per milliliter. Blinded validation revealed an area under the curve of 0.87 for plasma specimens from 96 asbestos-exposed persons as compared with 48 patients with mesothelioma.
Plasma fibulin-3 levels can distinguish healthy persons with exposure to asbestos from patients with mesothelioma. In conjunction with effusion fibulin-3 levels, plasma fibulin-3 levels can further differentiate mesothelioma effusions from other malignant and benign effusions. (Funded by the Early Detection Research Network, National Institutes of Health, and others.)
Collagen gel contraction by ARPE-19 is controlled by epithelial membrane protein 2 (EMP2) through focal adhesion kinase (FAK) activation. The purpose of this study was to test the role of EMP2 in the cellular context of FAK activation.
The ARPE-19 cell line was recombinantly modified to increase the expression of EMP2 and was used in this study. Quantification of FAK and Src phosphorylation was determined with Western blot analysis of whole cell lysates with the use of specific antibodies for different target sites of phosphorylation. Coimmunoprecipitation of whole cell lysates with an antibody against EMP2, followed by Western blot analysis and identification of FAK, was performed. Focal adhesions and their relationship to EMP2 were identified with immunofluorescence and confocal microscopy. F-actin distribution was identified using fluorescence microscopy, and α- smooth muscle actin (α-SMA) expression was quantified with Western blot analysis and specific antibodies. Adhesion to collagen type I was determined with a binding assay.
EMP2 overexpression led to increased FAK phosphorylation at all measured phosphorylation sites. Coimmunoprecipitation and confocal microscopy provided evidence for a physical association between EMP2 and FAK. Increased EMP2 was also associated with altered distribution of focal adhesions, changes in actin organization, increased α-SMA expression, and increased adherence to a collagen-coated surface.
The EMP2-FAK association represents a novel protein-protein interaction, not previously reported, that demonstrates significant functional cellular responses in the context of in vitro models of proliferative vitreoretinopathy (PVR).
Proliferative vitreoretinopathy (PVR) occurs in approximately 10% of patients after retinal detachment. PVR results from a multiphase process that leads to an aberrant wound-healing strategy with contractile cellular forces and tractional retinal detachment (TRD). Epithelial membrane protein (EMP) 2 controls cell surface expression and function of integrin isoforms associated with cellular contraction in many cell types. Since EMP2 is highly expressed in retinal pigment epithelium, this study investigates the role of EMP2 in collagen gel contraction.
EMP2 expression was recombinantly modified in the ARPE-19 cell line. Cell surface integrin expression was assessed by flow cytometry. Collagen gel contraction was assessed by using an in vitro assay and the percentage of contraction was quantified. Proliferation and migration were measured by BrdU incorporation and a wound-healing assay, respectively. Cellular invasion was investigated with polycarbonate membranes coated with collagen.
EMP2 expression levels correlated positively with the ability to contract collagen gels. Compared with wild-type ARPE-19 cells, the cells with increased EMP2 expression exhibited enhanced contraction (P = 0.02), and decreased EMP2 expression concomitantly resulted in decreased contraction (P = 0.002). EMP2 overexpression resulted in reduced proliferation, migration, and integrin α1 and α2 integrin expression. EMP2 overexpression was associated with a 70% increase in FAK activation (P = 0.0003) and relative resistance of gel contraction to inhibitors of FAK/Src activation.
ARPE-19-mediated collagen gel contraction is a multistep process that requires integrin ligation and activation of the FAK/Src complex. EMP2 positively modulates collagen gel contraction by ARPE-19 cells through increased FAK activation.
Host-microbe interactions at the intestinal mucosal-luminal interface (MLI) are critical factors in the biology of inflammatory bowel disease (IBD).
To address this issue, we performed a series of investigations integrating analysis of the bacteria and metaproteome at the MLI of Crohn’s disease, ulcerative colitis, and healthy human subjects. After quantifying these variables in mucosal specimens from a first sample set, we searched for bacteria exhibiting strong correlations with host proteins. This assessment identified a small subset of bacterial phylotypes possessing this host interaction property. Using a second and independent sample set, we tested the association of disease state with levels of these 14 “host interaction” bacterial phylotypes.
A high frequency of these bacteria (35%) significantly differentiated human subjects by disease type. Analysis of the MLI metaproteomes also yielded disease classification with exceptional confidence levels. Examination of the relationships between the bacteria and proteins, using regularized canonical correlation analysis (RCCA), sorted most subjects by disease type, supporting the concept that host-microbe interactions are involved in the biology underlying IBD. Moreover, this correlation analysis identified bacteria and proteins that were undetected by standard means-based methods such as ANOVA, and identified associations of specific bacterial phylotypes with particular protein features of the innate immune response, some of which have been documented in model systems.
These findings suggest that computational mining of mucosa-associated bacteria for host interaction provides an unsupervised strategy to uncover networks of bacterial taxa and host processes relevant to normal and disease states.
metaproteome; microbiome; mucosal luminal interface; rRNA genes
Estrogen signaling is critical in the progression of tumors that bear estrogen receptors. In most patients with breast cancer, inhibitors that block interactions of estrogen with its receptors or suppress the production of endogenous estrogens are important interventions in the clinic. Recent evidence now suggests that estrogen also contributes to the pathogenesis of non–small cell lung cancer (NSCLC). We used a human lung cancer xenograph model system to analyze the effect of aromatase or estradiol on tumor growth. We further examined the level of protein expression of aromatase in 422 patients with NSCLC using a high-density tissue microarray. Results were confirmed and validated on an independent patient cohort (n = 337). Lower levels of aromatase predicted a greater chance of survival in women 65 years and older. Within this population, the prognostic value of aromatase was greatest in earlier stage lung cancer (stage I/II). In addition, for women with no history of smoking, lower aromatase levels were a strong predictor of survival. Our findings implicate aromatase as an early-stage predictor of survival in some women with NSCLC. We predict that women whose lung cancers have higher levels of aromatase might be good candidates for targeted treatment with aromatase inhibitors.
Estrogen signaling pathways may play a significant role in the pathogenesis of non-small cell lung cancers (NSCLC) as evidenced by the expression of aromatase and estrogen receptors (ERα and ERβ) in many of these tumors. Here we examine whether ERα and ERβ levels in conjunction with aromatase define patient groups with respect to survival outcomes and possible treatment regimens. Immunohistochemistry was performed on a high-density tissue microarray with resulting data and clinical information available for 377 patients. Patients were subdivided by gender, age and tumor histology, and survival data was determined using the Cox proportional hazards model and Kaplan-Meier curves. Neither ERα nor ERβ alone were predictors of survival in NSCLC. However, when coupled with aromatase expression, higher ERβ levels predicted worse survival in patients whose tumors expressed higher levels of aromatase. Although this finding was present in patients of both genders, it was especially pronounced in women ≥ 65 years old, where higher expression of both ERβ and aromatase indicated a markedly worse survival rate than that determined by aromatase alone. Conclusion: Expression of ERβ together with aromatase has predictive value for survival in different gender and age subgroups of NSCLC patients. This predictive value is stronger than each individual marker alone. Our results suggest treatment with aromatase inhibitors alone or combined with estrogen receptor modulators may be of benefit in some subpopulations of these patients.
NSCLC; tissue microarray; aromatase; estrogen receptor; immunohistochemistry; prognosis
Lung cancer is the most common cause of cancer mortality in male and female patients in the US. Although it is clear that tobacco smoking is a major cause of lung cancer, about half of all women with lung cancer worldwide are never-smokers. Despite a declining smoking population, the incidence of non-small cell lung cancer (NSCLC), the predominant form of lung cancer, has reached epidemic proportions particularly in women. Emerging data suggest that factors other than tobacco, namely endogenous and exogenous female sex hormones, have a role in stimulating NSCLC progression. Aromatase, a key enzyme for estrogen biosynthesis, is expressed in NSCLC. Clinical data show that women with high levels of tumor aromatase (and high intratumoral estrogen) have worse survival than those with low aromatase. The present and previous studies also reveal significant expression and activity of estrogen receptors (ERα, ERβ) in both extranuclear and nuclear sites in most NSCLC. We now report further on the expression of progesterone receptor (PR) transcripts and protein in NSCLC. PR transcripts were significantly lower in cancerous as compared to non-malignant tissue. Using immunohistochemistry, expression of PR was observed in the nucleus and/or extranuclear compartments in the majority of human tumor specimens examined. Combinations of estrogen and progestins administered in vitro cooperate in promoting tumor secretion of vascular endothelial growth factor and, consequently, support tumor-associated angiogenesis. Further, dual treatment with estradiol and progestin increased the numbers of putative tumor stem/progenitor cells. Thus, ER- and/or PR-targeted therapies may offer new approaches to manage NSCLC.
Progesterone; Estrogen; Steroid hormone receptor; Non-small cell lung cancer; VEGF; Progenitor cells; Cancer stem cells; Angiogenesis
Ample studies suggest that the cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) pathway plays a pivotal role in carcinogenesis and that COX-2 inhibition may help prevent lung cancer. Therefore, we conducted a randomized, double-blind, placebo-controlled trial of the COX-2 selective inhibitor celecoxib (400 mg bid for 6 months) in former-smokers (age ≥45, ≥30 pack-years of smoking, ≥1 year of sustained abstinence from smoking). We assessed the impact of celecoxib on cellular and molecular events associated with lung cancer pathogenesis; the primary endpoint was bronchial Ki-67 labeling index (Ki-67 LI). Of 137 randomized subjects, 101 completed both baseline and 6-month bronchoscopies and were evaluable for the primary endpoint analysis. The beneficial effect on Ki-67 LI was greater in the celecoxib arm (versus placebo) in a mixed-effects analysis (P = 0.0006), and celecoxib significantly decreased Ki-67 LI by an average of 34%, whereas placebo increased Ki-67 LI by an average of 3.8% (P = 0.04; t-test). Participants crossed over to the other study arm at 6 months. Therefore, at 12 months all remaining participants had received 6 months of celecoxib, and their decreases in Ki-67 LI correlated with a reduction and/or resolution of lung nodules on computed tomography. Celecoxib significantly reduced plasma c-reactive protein and interleukin-6 mRNA and protein and increased 15(S)-hydroxy-eicosatetraenoic acid levels in BAL samples. The baseline ratio of COX-2 to 15-hydroxyprostaglandin dehydrogenase mRNA in bronchoalveolar lavage (BAL) cells was a significant predictive marker of Ki-67 response to celecoxib (P = 0.002). Our collective findings support the continued investigation of celecoxib for lung cancer chemoprevention in former smokers at a low risk of cardiovascular disease.
COX-2; 15-PGDH; PGE2; CRP; IL-6; 15-HETE
The GATA family members are zinc finger transcription factors involved in cell differentiation and proliferation. GATA3 in particular is necessary for mammary gland maturation, and its loss has been implicated in breast cancer development. Our goal was to validate the ability of GATA3 expression to predict survival in breast cancer patients. Protein expression of GATA3 was analyzed on a high density tissue microarray consisting of 242 cases of breast cancer. We associated GATA3 expression with patient outcomes and clinicopathological variables. Expression of GATA3 was significantly increased in breast cancer, in situ lesions, and hyperplastic tissue compared to normal breast tissue. GATA3 expression decreased with increasing tumor grade. Low GATA3 expression was a significant predictor of disease-related death in all patients, as well as in subgroups of estrogen receptor positive or low grade patients. Additionally, low GATA3 expression correlated with increased tumor size and estrogen and progesterone receptor negativity. GATA3 is an important predictor of disease outcome in breast cancer patients. This finding has been validated in a diverse set of populations. Thus, GATA3 expression has utility as a prognostic indicator in breast cancer.
Tissue microarray; breast cancer; tumor marker; prognostic marker
Aberrant interactions between the host and the intestinal bacteria are thought to contribute to the pathogenesis of many digestive diseases. However, studying the complex ecosystem at the human mucosal-luminal interface (MLI) is challenging and requires an integrative systems biology approach. Therefore, we developed a novel method integrating lavage sampling of the human mucosal surface, high-throughput proteomics, and a unique suite of bioinformatic and statistical analyses. Shotgun proteomic analysis of secreted proteins recovered from the MLI confirmed the presence of both human and bacterial components. To profile the MLI metaproteome, we collected 205 mucosal lavage samples from 38 healthy subjects, and subjected them to high-throughput proteomics. The spectral data were subjected to a rigorous data processing pipeline to optimize suitability for quantitation and analysis, and then were evaluated using a set of biostatistical tools. Compared to the mucosal transcriptome, the MLI metaproteome was enriched for extracellular proteins involved in response to stimulus and immune system processes. Analysis of the metaproteome revealed significant individual-related as well as anatomic region-related (biogeographic) features. Quantitative shotgun proteomics established the identity and confirmed the biogeographic association of 49 proteins (including 3 functional protein networks) demarcating the proximal and distal colon. This robust and integrated proteomic approach is thus effective for identifying functional features of the human mucosal ecosystem, and a fresh understanding of the basic biology and disease processes at the MLI.
Endometrial cancer (EC) is a common malignancy worldwide. It is often preceded by endometrial hyperplasia, whose management and risk of neoplastic progression vary. Previously, we have shown that the tetraspan protein Epithelial Membrane Protein-2 (EMP2) is a prognostic indicator for EC aggressiveness and survival. Here we validate the expression of EMP2 in EC, and further examine whether EMP2 expression within preneoplastic lesions is an early prognostic biomarker for EC development.
A tissue microarray (TMA) was constructed with a wide representation of benign and malignant endometrial samples. The TMA contains a metachronous cohort of cases from individuals who either developed or did not develop EC. Intensity and frequency of EMP2 expression were assessed using immunohistochemistry.
There was a stepwise, statistically-significant increase in the average EMP2 expression from benign to hyperplasia to atypia to EC. Furthermore, detailed analysis of EMP2 expression in potentially premalignant cases demonstrated that EMP2 positivity was a strong predictor for EC development.
EMP2 is an early predictor of EC development in preneoplastic lesions. In addition, combined with our previous findings, these results validate that EMP2 as a novel biomarker for EC development.
epithelial membrane protein-2; endometrial cancer; metachronous; tissue microarray; tumor biomarker
The protein 14-3-3σ is involved in the regulation of cellular processes such as apoptosis, cell cycle progression and proliferation. Disruption of protein expression has been implicated in a number of malignancies. Here we examine the expression pattern of 14-3-3σ in breast cancer and specifically consider whether expression in ductal carcinoma in situ (DCIS) lesions is predictive of disease outcome. We examined 14-3-3σ protein expression and localization using immunohistochemical staining on a high-density tissue microarray consisting of 157 invasive breast cancer patients. Statistical analyses were used to assess the correlation of 14-3-3σ expression with clinico-pathological parameters and patient outcome. We observed a statistically significant increase in 14-3-3σ protein expression in ductal hyperplasia, DCIS, and invasive ductal carcinoma (IDC) as compared normal glandular epithelium. In IDC, lower expression of 14-3-3σ tended to predicted poorer survival time while in DCIS lesions, there was a stronger correlation between relatively higher levels of 14-3-3σ predicting shorter survival time. Further, of patients who had concurrent DCIS and IDC lesions, those that exhibited a decrease of 14-3-3σ expression from DCIS to IDC had significantly shorter survival time. Our findings indicate that 14-3-3σ expression may be a useful prognostic indicator for survival in patients with breast cancer with an elevated 14-3-3σ in earlier disease predicting a less favorable disease outcome. To our knowledge this is the first published study associating 14-3-3σ protein expression with breast cancer survival.
Tissue microarray; breast cancer; tumor marker; 14-3-3 σ; prognostic marker; DCIS
Smoking is the most important known risk factor for the development of lung cancer. Tobacco exposure results in chronic inflammation, tissue injury and repair. A recent hypothesis argues for a stem/progenitor cell involved in airway epithelial repair that may be a tumor-initiating cell in lung cancer, and which may be associated with recurrence and metastasis. We used immunostaining, quantitative real-time PCR, Western blots and lung cancer tissue microarrays to identify subpopulations of airway epithelial stem/progenitor cells under steady state conditions, normal repair, aberrant repair with premalignant lesions and lung cancer and their correlation with injury and prognosis. We identified a population of keratin 14 (K14)-expressing progenitor epithelial cells that was involved in repair after injury. Dysregulated repair resulted in persistence of K14+ cells in the airway epithelium in premalignant lesions. The presence of K14+ cells in non-small cell lung cancer (NSCLC) samples predicted poorer outcomes. This was especially true in smokers where the presence of K14+ cells in NSCLC was predictive of metastasis. The presence of K14+ progenitor airway epithelial cells in NSCLC predicted a poor prognosis and this predictive value was strongest in smokers, where it also correlated with metastasis. This suggests that reparative K14+ progenitor cells may be tumor-initiating cells in this subgroup of smokers with NSCLC.
Lung carcinogenesis; dysregulated repair; injury
The tetraspan protein epithelial membrane protein-2 (EMP2) has been shown to regulate the surface display and signaling from select integrin pairs, and it was recently identified as a prognostic biomarker in human endometrial cancer. In this study, we assessed the role of EMP2 in human ovarian cancer.
We examined the expression of EMP2 within a population of women with ovarian cancer using tissue microarray assay technology. We evaluated the efficacy of EMP2-directed antibody therapy using a fully human recombinant bivalent antibody fragment (diabody) in vitro and ovarian cancer xenograft models in vivo.
EMP2 was found to be highly expressed in over 70% of serous and endometrioid ovarian tumors compared to non-malignant ovarian epithelium using a human ovarian cancer tissue microarray. Using anti-EMP2 diabody, we evaluated the in vitro response of 9 human ovarian cancer cell lines with detectable EMP2 expression. Treatment of human ovarian cancer cell lines with anti-EMP2 diabodies induced cell death and retarded cell growth, and these response rates correlated with cellular EMP2 expression. We next assessed the effects of anti-EMP2 diabodies in mice bearing xenografts from the ovarian endometrioid carcinoma cell line OVCAR5. Anti-EMP2 diabodies significantly suppressed tumor growth and induced cell death in OVCAR5 xenografts.
These findings indicate that EMP2 is expressed in the majority of ovarian tumors and it may be a feasible target in vivo.
Epithelial membrane protein-2; ovarian cancer; antibody therapy; diabody; xenograft
Raf-1 kinase inhibitor protein (RKIP) has been reported to negatively regulate signal kinases of major survival pathways. RKIP activity is modulated in part by phosphorylation on Serine 153 by protein kinase C, which leads to dissociation of RKIP from Raf-1. RKIP expression is low in many human cancers and represents an indicator of poor prognosis and/or induction of metastasis. The prognostic power has typically been based on total RKIP expression and has not considered the significance of phospho-RKIP.
The present study examined the expression levels of both RKIP and phospho-RKIP in human lung cancer tissue microarray proteomics technology.
Total RKIP and phospho-RKIP expression levels were similar in normal and cancerous tissues. phospho-RKIP levels slightly decreased in metastatic lesions. However, the expression levels of phospho-RKIP, in contrast to total RKIP, displayed significant predictive power for outcome with normal expression of phospho-RKIP predicting a more favorable survival compared to lower levels (P = 0.0118); this was even more pronounced in more senior individuals and in those with early stage lung cancer.
This study examines for the first time, the expression profile of RKIP and phospho-RKIP in lung cancer. Significantly, we found that phospho-RKIP was a predictive indicator of survival.
Tissue microarray (TMA) data are commonly used to validate the prognostic accuracy of tumor markers. For example, breast cancer TMA data have led to the identification of several promising prognostic markers of survival time. Several studies have shown that TMA data can also be used to cluster patients into clinically distinct groups. Here we use breast cancer TMA data to cluster patients into distinct prognostic groups.
We apply weighted correlation network analysis (WGCNA) to TMA data consisting of 26 putative tumor biomarkers measured on 82 breast cancer patients. Based on this analysis we identify three groups of patients with low (5.4%), moderate (22%) and high (50%) mortality rates, respectively. We then develop a simple threshold rule using a subset of three markers (p53, Na-KATPase-β1, and TGF β receptor II) that can approximately define these mortality groups. We compare the results of this correlation network analysis with results from a standard Cox regression analysis.
We find that the rule-based grouping variable (referred to as WGCNA*) is an independent predictor of survival time. While WGCNA* is based on protein measurements (TMA data), it validated in two independent Affymetrix microarray gene expression data (which measure mRNA abundance). We find that the WGCNA patient groups differed by 35% from mortality groups defined by a more conventional stepwise Cox regression analysis approach.
We show that correlation network methods, which are primarily used to analyze the relationships between gene products, are also useful for analyzing the relationships between patients and for defining distinct patient groups based on TMA data. We identify a rule based on three tumor markers for predicting breast cancer survival outcomes.
Tissue microarray; breast cancer; tumor marker; prognostic marker; WGCNA
Endometrial cancer is the most common gynecologic malignancy diagnosed among women in developed countries. One recent biomarker strongly associated with disease progression and survival is epithelial membrane protein-2 (EMP2), a tetraspan protein known to associate with and modify surface expression of certain integrin isoforms. In this study, we show using a xenograft model system that EMP2 expression is necessary for efficient endometrial tumor formation, and we have started to characterize the mechanism by which EMP2 contributes to this malignant phenotype. In endometrial cancer cells, the focal adhesion kinase (FAK)/Src pathway appears to regulate migration as measured through wound healing assays. Manipulation of EMP2 levels in endometrial cancer cells regulates the phosphorylation of FAK and Src, and promotes their distribution into lipid raft domains. Notably, cells with low levels of EMP2 fail to migrate and poorly form tumors in vivo. These findings reveal the pivotal role of EMP2 in endometrial cancer carcinogenesis, and suggest that the association of elevated EMP2 levels with endometrial cancer prognosis may be causally linked to its effect on integrin-mediated signaling.
PMP22, a member of the GAS3 family of tetraspan proteins, is associated with a variety of neurological diseases. Previous studies have shown that PMP22 is expressed in proliferative endometrium, but its function within this tissue is poorly understood. In this study, we first characterized the expression of PMP22 in the human menstrual cycle and began to characterize its function in the endometrium.
Using a combination of immunohistochemistry and quantitative PCR, we characterized the expression of PMP22 in both proliferative and secretory endometrium. Differences in PMP22 expression between proliferative and secretory endometrium were determined using a Mann-Whitney U test. In order to investigate the influence of PMP22 on α6 integrin expression, cells were created that ectopically overexpressed PMP22 or expressed a siRNA to inhibit its expression. These cells were analyzed for changes in integrins and binding to extracellular matrices.
In this study, we show that PMP22 expression is higher in proliferative phase than secretory phase. Functionally, we have begun to characterize the functional significance of this expression. Previous studies have suggested a link between PMP22 and α6 integrin, and therefore we asked whether PMP22 could associate or potentially modulate the expression of α6 integrin. Expression of both PMP22 and α6 integrin were detectable in endometrial epithelial and stromal cells, and we show that both proteins can associate and colocalize with each other. To understand if PMP22 directly altered the expression of a6 integrin, we examined cell lines with modulated levels of the protein. Overexpression of PMP22 was sufficient to increase α6 integrin surface expression with a concominant increase in binding to the extracellular matrix laminin, while a reduction in PMP22 suppressed α6 integrin surface expression.
These findings suggest a physiologic role for PMP22 on the expression of α6 integrin. We predict that this may be important for the maintainence of endometrial integrity and to the disease biology associated with altered levels of α6 integrin expression in the endometrium.
The protein AGR2 is a putative member of the protein disulfide isomerase family and was first identified as a homolog of the Xenopus laevis gene XAG-2. AGR2 has been implicated in a number of human cancers. In particular, AGR2 has previously been found to be one of several genes that encode secreted proteins showing increased expression in prostate cancer cells compared to normal prostatic epithelium.
Gene expression levels of AGR2 were examined in prostate cancer cells by microarray analysis. We further examined the relationship of AGR2 protein expression to histopathology and prostate cancer outcome on a population basis using tissue microarray technology.
At the RNA and protein level, there was an increase in AGR2 expression in adenocarcinoma of the prostate compared to morphologically normal prostatic glandular epithelium. Using a tissue microarray, this enhanced AGR2 expression was seen as early as premalignant PIN lesions. Interestingly, within adenocarcinoma samples, there was a slight trend toward lower levels of AGR2 with increasing Gleason score. Consistent with this, relatively lower levels of AGR2 were highly predictive of disease recurrence in patients who had originally presented with high-stage primary prostate cancer (P = 0.009).
We have shown for the first time that despite an increase in AGR2 expression in prostate cancer compared to non-malignant cells, relatively lower levels of AGR2 are highly predictive of disease recurrence following radical prostatectomy.