Abstract 4079: Pilot study of copper chaperon ATOX1 in oncogenesis of colon cancer

Abstract

Abstract INTRODUCTION: Copper is an essential element for normal function of many cellular enzymes. Copper homeostasis is maintained by a delicate network of copper transporters, which include human copper transporter 1(hCtr1), ATP7A, ATP7B, and copper chaperons including ATOX1, CCS, and Cox17. It has been known that copper is required for cell proliferation and tumor angiogenesis. Human tumor xenografts in mice with increased uptake of radioactive copper could be localized with positron emission tomography. Copper hypermetabolism might play a role in oncogenesis of human cancers. Recently, it was reported that ATOX1 is a transcription factor involved in copper-stimulated cell proliferation. In this pilot study, we analyzed expression of ATOX in human colon cancer tissues compared with its expression in normal colon tissues. In addition, preliminary experiments were conducted to study potential role of ATOX1 in oncogenesis of colon cancer. METHODS: Immunohistochemistry analysis was conducted to compare expression of ATOX1 in colon cancer tissues and normal colon tissues. A lentiviral vector encoding short-hairpin RNA (shRNA) specific for ATOX1 (Lenti-ATOX-shRNA) was constructed and used to transduce HCT-116 human colon cancer cells. Suppression of ATOX1 in HCT-116 cells transduced with Lenti-ATOX-shRNA (ATOX1-shRNA-HCT116) was confirmed by Western blot. MTT assay was conducted to assess effect of ATOX1 silencing on proliferation and sensitivity of ATOX1-shRNA-HCT-116 cells to copper, cisplatin and copper 8-hydroxyquinoline-2-carboxaldehyde thiosemicarbazide complex (CuHQTS), a new anticancer copper complex. The HCT-116 cells transduced by a lentivirus encoding a scramble shRNA (Scramble-shRNA-HCT116) were used as control. RESULTS: Over-expression of ATOX1 is identified in all of human colon cancer tissue samples (N=10), compared with expression of ATOX1 in normal colon tissue samples (N=10). Suppression of ATOX1 with ATOX1-shRNA in HCT116 cells was confirmed by Western blot assay. However, the results of MTT assay revealed no significant effect of ATOX1 silencing on proliferation and sensitivity of ATOX1-shRNA HCT116 cells to copper chloride, cisplatin, and CuHQTS, compared with proliferation and sensitivity of Scramble-shRNA-HCT116 to these drugs. CONCLUSIONS: ATOX1 holds potential as a new biomarker of colon cancer. Additional studies are necessary to determine the role of ATOX1 and other copper transporters in oncogenesis of colon cancer. Key words: colon cancer, copper metabolism, copper chaperon, ATOX1 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4079. doi:10.1158/1538-7445.AM2011-4079