Expression and prognostic significance of the oncogenic K2P potassium channel KCNK9 (TASK-3) in ovarian carcinoma.

Background/Aims: The TWIK-related acid sensitive K+ channel-3 (TASK-3) is an oncogenic potassium channel. We investigated the expression of TASK-3 in human ovaries, examined its prognostic significance, and determined effects of TASK-3 blockers on cell proliferation and apoptosis. Materials and Methods: Immunofluorescence and western blotting were used to investigate TASK-3 expression in two ovarian cancer cell lines, normal ovarian surface epithelium and cancer. Immunohistochemistry quantified expression in an ovarian cancer tissue microarray. The effect of TASK-3 blocking agents on cell proliferation was investigated with the CellTiter 96 (R) Aqueous Non-Radioactive Cell Proliferation assay and on apoptosis with flow cytometry. Results: TASK-3 expression was confirmed by immunofluorescence in the SKOV-3 and OVCAR-3 cell lines, normal ovaries (n=4) and ovarian tumours (n=4) and by western blotting in normal ovaries (n=6) and ovarian tumours (n=22). Immunohistochernistry demonstrated immunostaining in 99% of tumours (n=230). Increased immunostaining conferred a survival advantage (p=0.002; median survival of >24 months). TASK-3 blockers caused a significant reduction in cell proliferation and an increase in apoptosis in the SKOV-3 and OVCAR-3 cell lines. Conclusion: TASK-3 is expressed in epithelial ovarian cancer, conferring a significant survival advantage on patients with increased expression. TASK-3-modulating agents have a significant effect on cell proliferation and apoptosis. Based on these results, we propose that TASK-3 could prove to be both a novel tumour marker and a new therapeutic target in ovarian cancer, but further investigation is required.