Multidrug resistance-linked gene signature predicts overall survival of patients with primary ovarian serous carcinoma.

PURPOSE: This study assesses the ability of multidrug resistance (MDR)-associated gene expression patterns to predict survival in patients with newly diagnosed carcinoma of the ovary. The scope of this research differs substantially from that of previous reports, as a very large set of genes was evaluated whose expression has been shown to affect response to chemotherapy. EXPERIMENTAL DESIGN: We applied a customized TaqMan low density array, a highly sensitive and specific assay, to study the expression profiles of 380 MDR-linked genes in 80 tumor specimens collected at initial surgery to debulk primary serous carcinoma. The RNA expression profiles of these drug resistance genes were correlated with clinical outcomes. RESULTS: Leave-one-out cross-validation was used to estimate the ability of MDR gene expression to predict survival. Although gene expression alone does not predict overall survival (OS; P = 0.06), four covariates (age, stage, CA125 level, and surgical debulking) do (P = 0.03). When gene expression was added to the covariates, we found an 11-gene signature that provides a major improvement in OS prediction (log-rank statistic P < 0.003). The predictive power of this 11-gene signature was confirmed by dividing high- and low-risk patient groups, as defined by their clinical covariates, into four specific risk groups on the basis of expression levels. CONCLUSION: This study reveals an 11-gene signature that allows a more precise prognosis for patients with serous cancer of the ovary treated with carboplatin- and paclitaxel-based therapy. These 11 new targets offer opportunities for new therapies to improve clinical outcome in ovarian cancer.

Clinical relevance of multidrug resistance gene expression in ovarian serous carcinoma effusions.

The presence of tumor cells in effusions within serosal cavities is a clinical manifestation of advanced-stage cancer and is generally associated with poor survival. Identifying molecular targets may help to design efficient treatments to eradicate these aggressive cancer cells and improve patient survival. Using a state-of-the-art TaqMan-based qRT-PCR assay, we investigated the multidrug resistance (MDR) transcriptome of 32 unpaired ovarian serous carcinoma effusion samples obtained at diagnosis or at disease recurrence following chemotherapy. MDR genes were selected a priori based on an extensive curation of the literature published during the last three decades. We found three gene signatures with a statistically significant correlation with overall survival (OS), response to treatment [complete response (CR) vs other], and progression free survival (PFS). The median log-rank p-values for the signatures were 0.023, 0.034, and 0.008, respectively. No correlation was found with residual tumor status after cytoreductive surgery, treatment (with or without chemotherapy) and stage defined according to the International Federation of Gynecology and Obstetrics. Further analyses demonstrated that gene expression alone can effectively predict the survival outcome of women with ovarian serous carcinoma (OS, log-rank p = 0.0000; and PFS, log-rank p = 0.002). Interestingly, the signature for overall survival is the same in patients at first presentation and those who had chemotherapy and relapsed. This pilot study highlights two new gene signatures that may help in optimizing the treatment for ovarian carcinoma patients with effusions.

Mammalian target of rapamycin is a biomarker of poor survival in metastatic serous ovarian carcinoma.

The AKT signaling pathway is crucial for cancer cell survival. The objective of this study was to analyze the expression and clinical role of this pathway in serous ovarian carcinoma. Phospho-AKT and phospho-mammalian target of rapamycin protein expression was studied in 269 ovarian carcinomas (159 effusions, 38 primary carcinomas, 72 solid metastases) using immunohistochemistry. The association between AKT, mammalian target of rapamycin, and DJ-1 in effusions was quantitatively analyzed using flow cytometry. AKT phosphorylation status in effusions was further studied using Western blotting. Phospho-AKT and phospho-mammalian target of rapamycin were detected in the majority of tumors at all anatomical sites. Phospho-AKT expression in effusions was higher in grade 3 versus grades 1 and 2 tumors (P = .013). Flow cytometry analysis showed association between AKT, mammalian target of rapamycin, and DJ-1 expression (P < .001). Higher phospho-AKT Thr308/pan-AKT ratio by Western blotting was associated with more advanced International Federation of Gynecology and Obstetrics stage (P = .018) and a trend for poor response to chemotherapy at first disease recurrence (P = .051). Higher phospho-mammalian target of rapamycin protein expression in effusions by immunohistochemistry was associated with poor progression-free survival for patients with postchemotherapy effusions (P = .005). Phospho-mammalian target of rapamycin was an independent predictor of poor progression-free survival for patients with postchemotherapy effusions (P = .03). The association between activated AKT and mammalian target of rapamycin expression and clinicopathologic parameters of aggressive disease, including shorter patient survival, provides further evidence regarding the central role of this signaling pathway in ovarian carcinoma.