Philippa M. O’bRien

Background: Methods: Results: Conclusions:

Despite a high initial response rate to first-line platinum/paclitaxel chemotherapy, most women with epithelial ovarian cancer relapse with recurrent disease that becomes refractory to further cytotoxic treatment. We have previously shown that the E3 ubiquitin ligase, EDD, a regulator of DNA damage responses, is amplified and overexpressed in serous ovarian carcinoma. Given that DNA damage pathways are linked to platinum resistance, the aim of this study was to determine if EDD expression was associated with disease recurrence and platinum sensitivity in serous ovarian cancer. High nuclear EDD expression, as determined by immunohistochemistry in a cohort of 151 women with serous ovarian carcinoma, was associated with an approximately two-fold increased risk of disease recurrence and death in patients who initially responded to first-line chemotherapy, independently of disease stage and suboptimal debulking. Although EDD expression was not directly correlated with relative cisplatin sensitivity of ovarian cancer cell lines, sensitivity to cisplatin was partially restored in platinum-resistant A2780-cp70 ovarian cancer cells following siRNA-mediated knockdown of EDD expression. These results identify EDD as a new independent prognostic marker for outcome in serous ovarian cancer, and suggest that pathways involving EDD, including DNA damage responses, may represent new therapeutic targets for chemoresistant ovarian cancer.

Background: Currently, no specific immunohistochemical markers are available to differentiate primary mucinous epithelial ovarian cancer (MOC) from adenocarcinomas originating at other sites that have metastasised to the ovary, which may have an impact on patient management and prognosis. Aim: To investigate the expression of two intestinal markers, galectin 4 and meprin α, in mucinous carcinomas of the ovary and gastrointestinal tract. Methods: Using immunohistochemical analysis, the expression of galectin 4 and meprin α was investigated in 10 MOCs and in 38 mucinous adenocarcinomas of colon, pancreas, stomach and appendix, the most common sites of origin of ovarian metastases. Results: Total cytoplasmic galectin 4 expression was relatively consistent between the different carcinomas. Membranous meprin α expression was significantly lower in MOCs compared with gastrointestinal carcinomas. Moreover, meprin α expression showed greater discrimination between the ovarian and gastrointestinal carcinomas than the cytokeratins CK7 and CK20, the current standard immunohistochemical markers used to determine the tissue origin of mucinous carcinomas involving the ovaries. Conclusions: Meprin α is a useful additional marker in differentiating primary from secondary mucinous adenocarcinomas of the ovary.

Mucinous epithelial ovarian cancers (MOC) are clinically and morphologically distinct from the other histological subtypes of ovarian cancer. To determine the genetic basis of MOC and to identify potential tumour markers, gene expression profiling of 49 primary ovarian cancers of different histological subtypes was performed using a customised oligonucleotide microarray containing >59 000 probesets. The results show that MOC express a genetic profile that both differs and overlaps with other subtypes of epithelial ovarian cancer. Concordant with its histological phenotype, MOC express genes characteristic of mucinous carcinomas of varying epithelial origin, including intestinal carcinomas. Differences in gene expression between MOC and other histological subtypes of ovarian cancer were confirmed by RT-PCR and/or immunohistochemistry. In particular, galectin 4 (LGALS4) was highly and specifically expressed in MOC, but expressed at lower levels in benign mucinous cysts and borderline (atypical proliferative) tumours, supporting a malignant progression model of MOC. Hence LGALS4 may have application as an early and differential diagnostic marker of MOC.

Purpose: Dysregulation of cell cycle control, in particular G₁-S-phase transition, is implicated in the pathogenesis of most human cancers, including epithelial ovarian cancer (EOC). However, the prognostic significance of aberrant cell cycle gene expression in EOC remains unclear. Experimental Design: The expression of selected genes from the pRb pathway that regulates G₁-S-phase progression, including cyclin D1, p16^Ink4a, cyclin E, p27^Kip1, p21^Waf1/Cip1, and p53, was examined in a consecutive series of 134 serous EOC using immunohistochemistry and the results correlated to disease outcome. Results: Molecular markers predictive of reduced overall survival in univariate analysis were overexpression of cyclin D1 (P = 0.03) and p53 (P = 0.03) and reduced expression of p27^Kip1 (P = 0.05) and p21^Waf1/Cip1 (P = 0.02), with the latter three also being prognostic for a shorter progression-free interval. In addition, patients displaying overexpression of p53 with concurrent loss of p21^Waf1/Cip1 had a significantly shorter overall (P = 0.0008) and progression-free survival (P = 0.0001). On multivariate analysis, overexpression of cyclin D1 and combined loss of p21^Waf1/Cip1 in the presence of p53 overexpression were independent predictors of overall survival. Similarly, the combination of p21^Waf1/Cip1 loss and p53 overexpression was independently predictive of a shorter progression-free interval. Overexpression of p53 and cyclin E and reduced expression of p27^Kip1 and p21^Waf1/Cip1 were significantly associated with increasing tumor grade. Conclusions: This study confirms that dysregulation of cell cycle genes is common in EOC, and that aberrant expression of critical cell cycle regulatory proteins can predict patient outcome in serous EOC.

Purpose: A better understanding of the molecular pathways underlying the development of epithelial ovarian cancer (EOC) is critical to identify ovarian tumor markers for use in diagnostic or therapeutic applications. The aims of this study were to integrate the results from 14 transcript profiling studies of EOC to identify novel biomarkers and to examine their expression in early and late stages of the disease. Experimental Design: A database incorporating genes identified as being highly up-regulated in each study was constructed. Candidate tumor markers were selected from genes that overlapped between studies and by evidence of surface membrane or secreted expression. The expression patterns of three integral membrane proteins, discoidin domain receptor 1 (DDR1), claudin 3 (CLDN3), and epithelial cell adhesion molecule, all of which are involved in cell adhesion, were evaluated in a cohort of 158 primary EOC using immunohistochemistry. Results: We confirmed that these genes are highly overexpressed in all histological subtypes of EOC compared with normal ovarian surface epithelium, identifying DDR1 and CLDN3 as new biomarkers of EOC. Furthermore, we determined that these genes are also expressed in ovarian epithelial inclusion cysts, a site of metaplastic changes within the normal ovary, in borderline tumors and in low-grade and stage cancer. A trend toward an association between low CLDN3 expression and poor patient outcome was also observed. Conclusions: These results suggest that up-regulation of DDR1, CLDN3, and epithelial cell adhesion molecule are early events in the development of EOC and have potential application in the early detection of disease.