The extrinsic apoptosis pathway and its prognostic impact in ovarian cancer.

Objective: Death ligand FasL, its agonistic receptor Fas, tumor necrosis factor related apoptosis inducing ligand (TRAIL) and its agonistic death receptors DR4 and DR5 are implied in carcinogenesis, tumor immune surveillance and response to chemotherapy. TRAIL receptor agonists are evaluated as anti-cancer agents. This study aimed to relate expression of death ligands/receptors and downstream initiator caspase 8 and its anti-apoptotic homologue FLICE like inhibitory protein (c-FLIP) in ovarian cancers to chemotherapy response and survival.

Methods: Fas, FasL, TRAIL, DR4, DR5, caspase 8 and c-FLIP were determined immunohistochemically on a tissue microarray containing 382 ovarian cancers. Protein expression profiles were correlated with clinicopathologic variables, chemotherapy response and survival.

Results: Most tumors expressed DR4, DR5, caspase 8 and c-FLIP. High c-FLIP expression was associated with expression of caspase 8 and both TRAIL receptors. TRAIL and Fas were associated with low tumor grade and better progression-free survival (HR 0.63, p=.018 and HR 0.54, p=.012), respectively, and Fas with disease-specific survival (HR 0.49, p=0.009) in univariate analysis.

Conclusions: Fas and TRAIL loss is associated with dedifferentiation and worse prognosis. Expression of DR4, DR5, caspase 8 and c-FLIP by most ovarian cancers does not correlate with survival. High c-FLIP expression should be taken into account for death receptor targeted therapies.