Abstract 3824: Increased production of endogenous hydrogen sulfide (H2S) induced resistance to 5-FU and Oxaliplatin in colon cancer cells

Abstract

Abstract The combination of 5-FU and Oxaliplatin has been widely adopted as one of the first line chemotherapeutic regimens for colon cancer patients. However, the development of chemoresistance can lead to early recurrence and metastasis to distant organs, thus remaining a leading cause of death from colon cancer. In the present study, the increased production of hydrogen sulfide (H2S) in colon cancer tissues was validated and the effect of inhibition of production of endogenous H2S on the responses of colon cancer cells to 5-FU and Oxaliplatin was further analyzed. The results suggested that inhibition of the enzymatic activity of cystathionine-β-synthase (CBS), a major producer of H2S in colon cancer cells, significantly decreased the IC50s of both 5-FU and Oxaliplatin. Inhibition of CBS leads to decreased PI3K-Akt signaling and consequently decreased expression of thymidylate synthetase (TYMS), which is the target of 5-FU. Inhibition of CBS utilizing aminooxyacetic acid (AOAA) leads to increased production of reactive oxygen species (ROS) and exaggerated mitochondrial damages in colon cancer cells. Analysis performed on CompuSyn confirmed the synergetic effect of AOAA with both 5-FU and Oxaliplatin. In vivo imaging of tumorigenesis in nude mice further confirmed the effect of inhibition of CBS on the therapeutic effect of both 5-FU and Oxaliplatin. Together, these results suggested that inhibition of production of endogenous H2S might be a promising target for chemoresistance in colon cancer. Citation Format: Shanwen Chen, Shuai Zuo. Increased production of endogenous hydrogen sulfide (H2S) induced resistance to 5-FU and Oxaliplatin in colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3824.