β-carotene Suppresses Colon Cancer by Regulating M2 Macrophages and Tumor-associated Fibroblasts in Vitro and in Vivo (P02-015-19)

Tumor-associated macrophages (TAMs) and tumor-associated fibroblasts (TAFs) are consisted of tumor microenvironment (TME), which are involved in cancer progression and metastasis. Interactions within TME induce M2 macrophage phenotype, TAMs, and activate TAFs. β-carotene (BC) is a well-known antioxidant and showed protective effects on several diseases, including cancers. The object of this study is to investigate the anti-colorectal cancer (CRC) effects of BC by controlling macrophage polarization and fibroblast activation. TAMs were induced by treating with phorbol-12-myristate-13-acetate (PMA) and interleukin-4 (IL-4) in U937 cells and TAFs were induced by treating with transforming growth factor-β1 (TGF-β1) in CCD-18Co cells. To understand the effect of TME on cancer cells, HCT116 colon cancer cells were co-cultured with TAM or TAF conditioned media. The effects of BC on the expressions of cancer stem cells (CSCs) markers, epithelial-mesenchymal transition (EMT) markers along with invasion and migration were investigated. To confirm these results, the azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colitis-associated CRC mice model was used. BC decreased M2 macrophage polarization with activating IL-6/STAT3 signaling pathways and suppressed the expressions of fibroblast activation markers and EMT markers. In addition, BC inhibited the expressions of TME-induced CSCs markers and EMT and suppressed cell invasion and migration. Furthermore, BC supplementation suppressed tumorigenesis and the expressions of M2 macrophage-associated markers, including CD206, Arg1, and Ym-1 as well as CSCs markers in vivo. BC suppressed CRC by regulating TAMs and TAFs in vitro and in vivo, which indicated the potential therapeutic effects of BC on inflammatory diseases. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education and Brain Korea 21 Plus.