Mechanism of progestin resistance in endometrial precancer/cancer through Nrf2-survivin pathway

Progestin is commonly used for young patients suffering from endometrial hyperplasia or cancer. However, there is approximately 30% failure rate with unclear mechanism. We investigated if Nrf2-survivin pathway contributes the progestin resistance (PR) in this setting. Current study detected Nrf2 and survivin protein expression in post progestin treated endometrial tissue samples by using immunohistochemistry. Transfection of Nrf2 and survivin into endometrial cancer cells in vitro was done to determine the roles of Nrf2 and survivin in progestin resistance. Silence of survivin was then performed to explore if Nrf2-driven progestin resistance is mediated by survivin. Medorxyprogesterone acetate (MPA) and metformin were applied to examine the cellular proliferations under the controlled conditions. Overexpression of survivin and Nrf2 were found in progestin-resistant endometrial samples as well as in those areas with only partial responses after MPA treatment. In contrast, all responded endometrial tissue with complete decidualization showed negative expression of these two biomarkers. Exogenous overexpression of Nrf2 and survivin resulted in progestin resistance. In addition, reduction of survivin in endometrial cancer cells overcame the Nrf2 overexpression induced progestin resistance. Furthermore, Nrf2 and survivin expressions were effectively suppressed after withdrawal of MPA. Interestingly, metformin increased the progestin sensitivity by down regulation of Nrf2 and survivin. The findings suggest that dysregulation of Nrf2-survivin may represent part of the molecular mechanisms of progestin resistance in endometrial cancer. Detecting survivin and Nrf2 may predict progestin resistance, while targeting Nrf2 and survivin may represent a promising prevention and treatment strategy for endometrial cancer.