POU4F2/Brn-3b transcription factor is associated with survival and drug resistance in human ovarian cancer cells

The development of drug resistance following treatment with chemotherapeutic agents such as cisplatin (cis) and paclitaxel (pax) contributes to high morbidity and mortality in ovarian cancers. However, the molecular mechanisms underlying such changes are not well understood. In this study, we demonstrate that the Brn-3b transcription factor was increased in different ovarian cancer cells including SKOV3 and A2780 following treatment with cis and pax. Furthermore, sustained increases in Brn-3b were associated with survival in drug resistant cells and correlated with elevated HSP27 expression. In contrast, targeting Brn-3b for reduction using short interfering RNA (siRNA) also resulted in attenuated HSP27 expression. Importantly, blocking Brn-3b expression with siRNA in SKOV3 cells was associated with reduced cell numbers at baseline but also increased cell death after further treatment, indicating sensitization of cells. Similar results were obtained in the metastatic IP1 cell line derived from ascites of mice bearing SKOV3 tumours. These findings suggest that increased Brn-3b may confer resistance to chemotherapeutic drugs in ovarian cancer cells by regulating key target genes such as HSP27 and that targeting Brn-3b may provide a novel mechanism for treatment of drug resistant ovarian cancers.