Effect of pharmacologic inhibition of c-Jun N-terminal kinase (JNK) signaling pathway on cell proliferation and cell cycle progression in human granulosa cell tumor.

Abstract

e22004 Background: No data are available regarding the signaling pathways that controls the proliferation of granulosa cell tumors (GCT). Preliminary findings showing the activation of c-Jun N-terminal kinase (JNK) signaling pathway in the proliferating granulosa cells has led us to investigate the role of this pathway in human GCT. Methods: Human GCT line COV 434 was used. Cell proliferation was monitored real-time quantitatively for 120h using an impedance-based system. Two different pharmacologic JNK inhibitors SP600125 and AS601245 were used. Their inhibitory concentrations were determined in western blot. Cell cycle was analyzed with flow cytometry and apoptosis with yo-pro-1 staining. Results: First, the growth characteristics of this cell line was delineated (Table 1A). Then the cells were treated with the inhibitors at the indicated doses during the log phase. Their proliferation was significantly halted in a dose-dependent manner by both inhibitors (Table 1B). Furthermore, the cells failed to complete mitosis, and began to accumulate at G2 in a dose dependent manner when JNK pathway was interrupted with AS601245 (59%) and SP600125 (39%) during G2/M transition compared to control cells (7%) proceeding through G2/M phase regularly (p<0.001). Compared to 3.5% of control cells, 14% and 30% of the cells underwent apoptosis when treated with 50 µM SP600125 and AS601245, respectively. At 100 µM, the apoptotic fraction increased to 68% and 76%, respectively (p<0.01). Conclusions: These results suggest that pharmacologic manipulation of JNK pathway may provide a therapeutic benefit in the treatment of GCT for which currently, no curative therapy exists beyond surgery. Funded by a Grant to Ozgur Oktem (TUBITAK109S164). [Table: see text]