Retaining MKP1 expression and attenuating JNK-mediated apoptosis by RIP1 for cisplatin resistance through miR-940 inhibition
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Qiong Wang1,4,*, Shaoqing Shi1,4,*, Weiyang He2, Mabel T. Padilla4, Lin Zhang1, Xia Wang1, Bin Zhang3, Yong Lin4
1 Laboratory of Molecular and Translational Medicine, Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education at Sichuan University, Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, P.R. China;
2 Department of Urology, The First Affiliated Hospital, Chongqing, P.R. China
3 Department of Social Medicine, School of Public Health, Chongqing Medical University, Chongqing, P.R. China;
4 Molecular Biology and Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, NM, USA.
* These authors contributed equally to the work
Yong Lin, email:
Bin Zhang, email:
Keywords: RIP1, MKP1, JNK, cisplatin, lung cancer, apoptosis, chemoresistance.
Received: January 8, 2014 Accepted: February 25, 2014 Published: February 25, 2014
The elucidation of chemoresistance mechanisms is important to improve cancer patient survival. In this report, we investigated the role and mechanism through which receptor-interacting protein 1 (RIP1), a mediator in cell survival and death signaling, participates in cancer’s response to chemotherapy. In lung cancer cells, knockdown of RIP1 substantially increased cisplatin-induced apoptotic cytotoxicity, which was associated with robust JNK activation. The expression of the JNK inactivating phosphatase, MKP1, was substantially reduced in RIP1 knockdown cells. Although MKP1 protein stability was not altered by RIP1 suppression, the synthesis rate of MKP1 was dramatically reduced in RIP1-suppressed cells. Furthermore, we found that the expression of miR-940 was substantially increased in RIP1 knockdown cells. Knockdown of miR-940 restored MKP1 expression and attenuated cisplatin-induced JNK activation and cytotoxicity. Importantly, ectopic expression of MKP1 effectively attenuated cisplatin-induced JNK activation and cytotoxicity. In addition, activation of the JNK upstream signaling kinase, MKK4, was also potentiated in RIP1 knockdown cells. Altogether, our results suggest that RIP1 contributes to cisplatin resistance by suppressing JNK activation that involves releasing miR-940-mediated inhibition of MKP1 and suppressing activation of MKK4. Intervention targeting the RIP1/miR-940/MKP1/JNK pathway may be used to sensitize platinum-based chemotherapy.
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