Pro‐tumorigenic Effects of Hydrogen Sulfide (H2S) on Normal Colonic Fibroblasts (NCF) and Colorectal (CRC) Cancer‐Associated Fibroblasts (CAF)

Abstract

IntroductionBidirectional paracrine signaling between cancer cells and fibroblasts in the stroma facilitates tumor progression. We have shown that CRC cells upregulate cystathionine β synthase (CBS), resulting in H2S production, when compared to normal colonic epithelium, and that CRC‐derived H2S increases CRC growth, migration, and tumor angiogenesis. The aims of this study are to determine whether H2S can promote CAF proliferation and migration, and stimulate NCF to develop into a CAF‐like phenotype.MethodsHuman CAF from CRC and NCF were collected under an IRB approved protocol and established in culture. CAF were grown for up to 120h in the presence of vehicle or a slow‐release H2S donor, GYY4137. CAFs were allowed to migrate through transwell chambers toward conditioned media (CM) from HCT116 or normal colon mucosal cells (NCM356). Western blots for NCF and CAF were performed to determine CBS expression levels.ResultsH2S donor GYY4137 (30‐300μM) significantly increased proliferation of CAF, but not NCF. CAF migrate toward HCT116 CM, but not NCM356 CM. CAF migrate significantly less toward CM from HCT116 cells with shRNA‐mediated silencing of CBS or CBS inhibitor aminooxyacetic acid. NCF cells express less basal CBS protein compared to CAF cells. NCF cells can be induced to express CBS enzyme after exposure to HCT116 CM for 48h.ConclusionsH2S enhances CRC CAF cell proliferation and migration. Furthermore, when NCF cells are exposed to CRC CM, the NCF cells induce expression of CBS enzyme. The results support the hypothesis that the gasotransmitter H2S promotes pro‐tumorigenic activities in the CRC microenvironment.