BCL6 is a negative prognostic factor and exhibits pro-oncogenic activity in ovarian cancer.

BACKGROUND Dysregulation of BCL6 plays critical oncogenic roles and facilitates tumorigenesis in various malignancies. However, whether the aberrant expression of BCL6 in ovarian carcinoma is associated with malignancy, metastasis or prognosis remains unknown. Our study aimed to investigate the expression of BCL6 in ovarian carcinoma and its possible correlation with clinicopathological features as well as patient survival to reveal its biological effects in ovarian tumor progression. METHODS Immunochemistry analysis was performed in 105 cases of ovarian carcinoma covering the histological types of serous, endometrioid and clear cell. Spearman analysis was used to calculate the correlation between pathological parameters and the expression of BCL6. Kaplan-Meier method and Cox proportional hazards analysis were used to analyze the disease-specific survival (DSS) and disease-free survival (DFS). We also assessed whether overexpression and knockdown of BCL6 influence in vitro cell proliferation, cell cycle progression, as well as tumor cell invasion and migration. RESULTS The expression of BCL6 was higher in all three major kinds of ovarian cancer in comparison with paratumorous epithelium. BCL6 expression was tightly correlated with FIGO staging, lymph node metastasis and recurrence. Higher expression of BCL6 led to a significantly poorer DSS and DFS and multivariate analysis revealed that BCL6 was an independent risk factor of DSS and DFS. Enforced overexpression of BCL6 in ovarian tumor cells stimulated proliferation by inducing G1-S transition, and promoted tumor cell invasion and migration. Conversely, RNA interference-mediated silencing BCL6 expression inhibited proliferation by altered cell cycle progression and reduced the ability of the cells to migrate, and invade the extracellular matrix in culture. CONCLUSIONS Our study suggests that the inappropriate activation of BCL6 predicts poor prognosis and promotes tumor progression in ovarian carcinoma. Targeting BCL6 could be a novel therapeutic choice for treating ovarian carcinoma patients.