Bmi1 inhibition enhances the sensitivity of pancreatic cancer cells to gemcitabine

// Tao Yin 1, * , Zhengle Zhang 1, * , Bin Cao 2 , Qingke Duan 1 , Pengfei Shi 1 , Hengqiang Zhao 1 , Soriba Naby Camara 1 , Qiang Shen 3 , Chunyou Wang 1 1 Department of Pancreatic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China 2 Department of Hepatobiliary Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China 3 Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, TX, USA * These authors have contributed equally to this work Correspondence to: Tao Yin, email: ytwhun@126.com Chunyou Wang, email: chunyouwang52@126.com Keywords: pancreatic cancer, Bmi1, gemcitabine, chemotherapy, efficacy Received: September 25, 2015     Accepted: April 16, 2016     Published: May 11, 2016 ABSTRACT As the standard therapy for pancreatic cancer, gemcitabine shows limited efficacy in pancreatic cancer patients because of chemoresistance. Aberrant expression of Bmi1 has been reported to activate multiple growth-regulatory pathways and confer anti-apoptotic abilities to many cancer cells. However, the role of Bmi1 in response of pancreatic cancer cells towards gemcitabine resistance remains elusive. In this study, we found that certain dose of gemcitabine treatment induced Bmi1 expression in pancreatic cancer cells. Knockdown of Bmi1 enhanced ROS production and promoted the cytotoxic effect of gemcitabine. The increased oxidative stress upon gemcitabine treatment could disrupt mitochondrial membrane and decrease mitochondrial membrane potential, eventually leading to apoptosis. Bmi1 inhibition also suppressed the activation of NF-κB signaling and the expressions of downstream molecules in pancreatic cancer cells treated with gemcitabine. Moreover, we observed Bmi1 inhibition sensitized the pancreatic xenograft tumors to gemcitabine in vivo. Taken together, our study demonstrated that Bmi1 could decrease the sensitivity of pancreatic cancer cells to gemcitabine through increasing oxidative stress and inhibiting NF-κB signaling, thus Bmi1 may serve as a promising target for sensitizing pancreatic cancer cells to chemotherapy.