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Purpose: Currently available clinicopathologic prognostic factors are imperfect predictors of clinical course in advanced-stage epithelial ovarian cancer patients. New molecular predictors are needed to identify patients with higher risk of relapse or death from disease. In a retrospective study, we investigated the prognostic impact of activated leukocyte cell adhesion molecule (ALCAM) expression in epithelial ovarian cancer., Experimental Design: We analyzed the effect of cell-anchorage loss on ALCAM cellular localization in vitro and assessed ALCAM expression by immunohistochemistry in a series of 109 well-characterized epithelial ovarian cancer patient samples. Chi-square test, Kaplan-Meier method, and Cox proportional hazard analyses were used to relate ALCAM cellular localization to clinical-pathologic parameters and to overall survival (OS) rate., Results: Loss of epithelial ovarian cancer cell anchorage was associated both in vitro and in vivo with decreased ALCAM membrane expression. In vivo, ALCAM was localized to cell membrane in normal surface ovarian epithelium, whereas in 67% of the epithelial ovarian cancer samples, membrane localization was decreased or even lost, and the molecule was mainly expressed in cytoplasm. Median OS in this group of patients was 58 months, whereas a median OS was not yet reached in patients with ALCAM membrane localization (P = 0.036, hazard ratio [HR] = 2.0, 95% confidence interval [CI] 1.1 to 3.5). In a multivariate Cox regression model including all the available clinicopathologic variables, loss of ALCAM membrane expression was an independent factor of unfavorable prognosis (P = 0.042, HR = 2.15, 95% CI: 1.0 to 4.5)., Conclusions: Decreased/lost ALCAM membrane expression is a marker of poorer outcome in epithelial ovarian cancer patients and might help to identify patients who could benefit from more frequent follow-up or alternative therapeutic modalities.

Purpose: Ovarian carcinoma is a highly lethal malignancy that often becomes resistant to chemotherapy. Alterations in apoptotic signals and p53 status contribute to drug resistance, and CD95-mediated apoptosis is also deficient in resistant cells. We analyzed the mechanism of resistance to CD95-mediated apoptosis in ovarian carcinoma cell lines differing in p53 status., Experimental Design: CD95-mediated apoptosis was induced by agonistic anti-CD95 antibody, and the apoptotic cascade was monitored with biochemical and functional assays., Results: CD95-mediated apoptosis was blocked in human ovarian cancer cells. In cell lines with wild-type p53, treatment with the protein synthesis inhibitor cycloheximide (CHX) together with anti-CD95 overcame the resistance, suggesting the presence of a labile inhibiting protein. Indeed, the labile protein cellular FLICE-inhibitory protein long form (c-FLIP(L)) was found to block caspase-8 recruitment to the death-inducing signaling complex (DISC), and sensitization of cells by CHX was due to c-FLIP(L) down-modulation at the DISC level. Down-regulation of c-FLIP(L) with antisense oligonucleotides increased CD95-mediated apoptosis as in cells sensitized by CHX, demonstrating the direct involvement of c-FLIP(L) in apoptosis resistance. Removal of c-FLIP(L) block at DISC level allowed full activation of the mitochondrial pathway and, eventually, apoptosis in wild-type p53 cells, whereas in cells with mutated p53, c-FLIP(L) involvement in CD95-mediated apoptosis resistance appeared to be irrelevant. Immunohistochemical analysis of an ovarian tumor tissue array revealed c-FLIP(L) expression in samples with no p53 accumulation (P = 0.034), and a significant (P = 0.037) inverse relationship between c-FLIP(L) and p53 expression levels was also observed in 27 epithelial ovarian cancer specimens with known p53 status., Conclusion: The inhibitory protein c-FLIP(L) is involved in resistance to CD95-mediated apoptosis in ovarian carcinoma cells with wild-type p53.