Abstract 766: Human ABCB1 and ABCG2 confer acquired resistance to Polo-like kinase 1 inhibitors, BI 2536, volasertib and GSK641364

Abstract

Abstract The overexpression of the serine/threonine specific polo-like kinase 1 (Plk1) has been detected in various types of cancer, and thus has fast become an attractive therapeutic target for cancer therapy. Plk1 inhibitors BI 2536, volasertib and GSK461364, were designed to selectively inhibit cancer cell proliferation by promoting G2/M cell cycle arrest at nanomolar concentrations. Unfortunately, alike most chemotherapeutic agents, the development of acquired resistance to Plk1 inhibitors is prone to present a significant therapeutic challenge. One of the most common mechanisms for acquired resistance in cancer chemotherapy is associated with the overexpression of ATP-binding cassette (ABC) transporters ABCB1, ABCC1 and ABCG2. Here, we discovered that in human cancer cells, the overexpression of ABCB1 and/or ABCG2 can lead to acquired resistance to three selective Plk1 inhibitors, BI 2536, volasertib and GSK461364. Moreover, these Plk1 inhibitors stimulate the ATPase activity of ABCB1 and ABCG2, as well as competitively inhibit the drug substrate transport mediated by ABCB1 and ABCG2. More significantly, the reduced chemosensitivity and Plk1 inhibitors-mediated G2/M cell cycle arrest in cancer cells overexpressing either ABCB1 or ABCG2 can be significantly restored in the presence of selective inhibitor of ABCB1 and ABCG2. Taken together, our findings indicate that in order to circumvent ABCB1 or ABCG2-mediated acquired resistance to Plk1 inhibitors, a combined regimen of Plk1 inhibitors and modulators or clinically active drugs that potently inhibit the function of ABC drug transporters, should be considered as a potential treatment strategy in the clinic. Citation Format: Chung-Pu Wu, Hong-May Sim, Suresh V. Ambudkar. Human ABCB1 and ABCG2 confer acquired resistance to Polo-like kinase 1 inhibitors, BI 2536, volasertib and GSK641364. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 766. doi:10.1158/1538-7445.AM2014-766