Wee1 is a novel independent prognostic marker of poor survival in post-chemotherapy ovarian carcinoma effusions

Abstract

Objective: Wee1-like kinase (Wee1) is a tyrosine kinase which negatively regulates entry into mitosis at the G2 to M-phase transition and has a role in inhibition of unscheduled DNA replication in S-phase. The present study investigated the clinical role of Wee1 in advanced-stage (FIGO III-IV) ovarian serous carcinoma.

Methods: Wee1 protein expression was analyzed in 287 effusions using immunohistochemistry. Expression was analyzed for association with clinicopathologic parameters, including survival. Forty-five effusions were additionally studied using Western blotting. Wee1 was further silenced in SKOV3 and OVCAR8 cells by siRNA knockdown and proliferation was assessed.

Results: Nuclear expression of Wee1 in tumor cells was observed in 265/287 (92%) and 45/45 (100%) effusions by immunohistochemistry and Western blotting, respectively. Wee1 expression by immunohistochemistry was significantly higher in post-chemotherapy disease recurrence compared to pre-chemotherapy effusions obtained at diagnosis (p=0.002). Wee1 silencing in SKOV3 and OVCAR8 cells reduced proliferation. In univariate survival analysis of the entire cohort, a trend was observed between high (>25% of cells) Wee1 expression and poor overall survival (p=0.083). Survival analysis for 109 patients with post-chemotherapy effusions showed significant association between Wee1 expression and poor overall survival (p=0.004), a finding which retained its independent prognostic role in Cox multivariate analysis (p=0.003).

Conclusions: Wee1 is frequently expressed in ovarian serous carcinoma effusions, and its expression is significantly higher following exposure to chemotherapy. The present study is the first to report that Wee1 is an independent prognostic marker in serous ovarian carcinoma.

Keywords: Effusions; Ovarian carcinoma; Survival; Tumor progression; Wee1.