CyclinG1 Amplification Enhances Aurora Kinase Inhibitor-Induced Polyploid Resistance and Inhibition of Bcl-2 Pathway Reverses the Resistance

• Main Authors: Wenfeng Zhang, Jie Xu, Dexiang Ji, Zhangyun Li, Wenxing He, Fei Yang, Huiyin Lan, Yu Wang, Zhengping Wu, Xiaoshan Liu, Shanhua Huang, Longkun Li, Weihua Zhou
• Format: Article
• Language: English
• Published: Cell Physiol Biochem Press GmbH & Co KG 2017-08-01
• Series: Cellular Physiology and Biochemistry
• Subjects: CyclinG1; Polyploidy; Resistance; Bcl-2 family; Targeted therapy; Breast Cancer
• Online Access: http://www.karger.com/Article/FullText/480322
• ISSN: 1015-8987; 1421-9778

Background/Aims: CyclinG1 (CycG1) is frequently overexpressed in solid tumors and overexpression of CycG1 promotes cell survival upon paclitaxel exposure by inducing polyploidy. Whether and how CycG1 regulates polyploidization caused by small molecular targeted inhibitors remains unclear. Methods: Immunohistochemistry and immunoblotting were utilized to examine protein expression. Cell proliferation was measured by ATPlite assay, and cell cycle distribution and apoptosis were measured by flow cytometry and/or DNA fragmentation assays. Results: Overexpression of CycG1 in breast cancer cells caused apoptosis-resistant polyploidy upon treatment with Aurora kinase inhibitor, ZM447439 (ZM). Addition of ABT-263, a small-molecule BH3 mimetic, to ZM, produced a synergistic loss of cell viability with greater sustained tumor growth inhibition in breast cancer cell lines. Decrease of Mcl-1 and increase of NOXA caused by ZM treatment, were responsible for the synergy. Furthermore, CycG1 was highly expressed in Triple-Negative-Breast-Cancer patients treated with paclitaxel and was paralleled by decreased cell survival. Conclusion: CycG1 is a crucial factor in ZM-induced polyploidy resistance, and ABT-263/ZM combination hold therapeutic utility in the CycG1-amplified subset of breast cancer and CycG1, thus, is a promising target in breast cancer.