Abstract 1605: Aurora-A promotes radio- and chemo- resistance through regulation of DNA damage response proteins.
Authors: Sun Huizhen , Wang Ziliang , Meng Jiao , Wang Yan , Qi Zihao , Xu Han , Lin Fengjuan , Gao Wen , Sun Jianmin , Hou Jing , Yang Gong 
Published: August 2014

Abstract
Background: Poor prognosis of cancer is usually resulted from radio- and chemo-resistance. Aurora-A, a serine/threonine kinase, associated with spindle separation and centrosome duplication, is overexpressed in many cancers.
Purposes: High expression of Aurora-A negatively regulates BRCA2, indicating that Aurora-A is probably associated with DNA damage repair, which may mediate resistance of radio- and chemo-therapy. This study was to investigate the role of Aurora-A in radio- and chemo-resistance in order to seek novel therapeutic methods for human cancer.
Materials and methods: Cell lines from breast cancer, pancreatic cancer and ovarian cancer, including those with either low Aurora-A expression (MCF-7, PANC-1 and OVCA420), or high Aurora-A expression (MDA-MB-231, BXPC3 and OVCA429), were used to overexpress or silence Aurora-A, BRCA1, or BRCA2. Cell growth curve and colony formation were tested by cell counting and soft agar assay. Flow cytometry and MTT were used to examine cell apoptosis or cell viability (IC50) after treatment with radiation and cisplatin or VX680 (Aurora-A inhibitor). Western blotting was used to test the expression of DNA damage responsive proteins. Immunofluorescence was used to detect intracellular localization of above proteins.
Results: Our data showed that introduction of Aurora-A or silencing of BRCA1 and BRCA2 increased cell growth and colony formation, while silencing of Aurora-A or introduction of BRCA1 and BRCA2 decreased cell proliferation and colony formation. Introduction of Aurora-A also reduced apoptosis in response to gamma-irradiation and cisplatin treatment, while silencing of Aurora-A or treatment of cells with VX680 enhanced apoptosis. Introduction of Aurora-A increased cell viability and IC50 in response to cisplatin treatment, while knockdown of Aurora-A or treatment with VX680 decreased cell viability and IC50. Western blot suggested that Aurora-A had a negative association with BRCA1 and BRCA2. Moreover, overexpression of Aurora-A either by introduction of Aurora-A cDNA or knockdown of BRCA1 or BRCA2 attenuated the expression of DNA damage responsive proteins including RAD51, H2AX, γH2AX, ATR, ERCC2, Chk1, pChk1, Chk2, pChk2,p53, pp53, DNApolζ, which was confirmed by Immunofluorescence.
Conclusions: Aurora-A regulates DNA damage responsive proteins including BRCA1, BRCA2, RAD51, H2AX, ERCC2, Chk1, Chk2, ATR, DNA pol ζ to confer cancer radio- and chemo-resistance. Therefore, DNA damage pathway should be essentially considered in the targeted therapy against Aurora-A in cancer patients either with activated Aurora-A or with inactivated BRCA1 or BRCA2.
Citation Format: Huizhen Sun, Ziliang Wang, Jiao Meng, Yan Wang, Zihao Qi, Han Xu, Fengjuan Lin, Wen Gao, Jianmin Sun, Jing Hou, Gong Yang. Aurora-A promotes radio- and chemo- resistance through regulation of DNA damage response proteins. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1605. doi:10.1158/1538-7445.AM2013-1605
Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.