Objective: Equilibrative and concentrative nucleoside transporters (ENTs and CNTs) mediate the cellular uptake of anticancer nucleosides and sensitivity to such compounds. We studied the expression of ENTs and CNTs in ovarian carcinoma effusions.
Methods: ENT1, ENT2, ENT4 and CNT3 expression was analyzed in 66 ovarian carcinoma effusions (61 peritoneal, 5 pleural) from 64 ovarian carcinoma patients by flow cytometry. The majority of patients received platinum-based chemotherapy. Results were analyzed for association with clinicopathologic parameters and survival.
Results: With the exception of one ENT2-negative effusion, ENT1, ENT2, ENT4 and CNT3 protein was detected on carcinoma cells in all effusions, with expression observed in 1-95% of tumor cells. Nucleoside transporter expression was comparable between peritoneal and pleural effusions and was unrelated to age, tumor grade, International Federation of Gynecology and Obstetrics (FIGO) stage, residual tumor volume after surgery, previous exposure to chemotherapy and response to chemotherapy at diagnosis (P > 0.05). No correlation was found between ENT or CNT expression and overall survival or progression-free survival, although higher ENT2 expression was associated with a trend for longer overall (45 vs. 23 months; P = 0.055) and progression-free (17 vs. 5 months; P = 0.087) survival.
Conclusion: Nucleoside transporters are frequently expressed in ovarian carcinoma effusions, but their expression generally appears to be unrelated to chemoresponse in this cancer in a cohort of patients treated by platinum-based chemotherapy. The role of ENT2 as a prognostic marker in this disease, as well as the role of these molecules in determining chemoresponse in patients treated by nucleoside analogs, merits further research.