TIPE regulates TGFB2 expression and induces extracellular M2 polarization in CRC

Abstract Background: M2 macrophages (M2) play a crucial role in the development of colorectal cancer (CRC). The elevated expression of TIPE in CRC is closely associated with CRC progression; however, the impact of TIPE on M2 polarization remains unclear. Methods: IHC, WB, flow cytometry, qPCR, and IF were used to verify the promoting effect of TIPE on M2 polarization in specimens and in vitro co-culture models. RNA-seq, ELISA, and WB were used to identify the secreted proteins regulated by TIPE and the underlying mechanism. CCK-8 assay, wound healing assay, and transwell invasion assay were used to verify the effect of M2 on CRC. In vivo experiments were used to identify the promoting effect of TIPE on M2 polarization. Results: In this study, we first demonstrated that the abnormal overexpression of TIPE in CRC promotes M2 polarization and is correlated with a poor prognosis for CRC patients. We then found that TIPE activates the P38 MAPK signaling pathway in CRC to regulate TGF?2 secretion and, furthermore, induces M2 macrophage polarization. In subcutaneous and lung xenograft models of CRC in nude mice, we found that TIPE regulates TGF?2 secretion from human CRC to promote M2 polarization of murine macrophages. Conclusion: These results indicate that TIPE is a potent oncogene for inducing M2 polarization. It is suggested that all cancers with high TIPE expression need to be alert to the production and infiltration of M2 macrophages, which provides a new perspective for cancer treatment. Overall design: The SW480 human colon cancer cell line was obtained from the Typical Culture Cell Bank of the Chinese Academy of Sciences in Shanghai, China. The cells were maintained in DMEM supplemented with 10% fetal bovine serum, 100IU/ml penicillin, and 100µg/ml streptomycin. Lentivirus was utilized for transfection of empty or TIPE overexpressed plasmids into SW480 cells, resulting in the creation of a TIPE overexpressed group (SW480OE) and an unloaded control group (SW480V). Transfection efficiency was assessed using western blot and qPCR techniques. The cells were incubated in a complete medium supplemented with puromycin (2µg/ml) for a minimum of two weeks prior to RNA-seq analysis.