FBXW7 Inhibited M2 Macrophage Polarization in Endometrial Cancer by Reducing CCL2 Secretion Through Ubiquitination of MYBL2 Subtitle: The Role of FBXW7 on M2 Macrophage Polarization in EC

Impeding M2 macrophage polarization has been suggested to slow the progression of endometrial Cancer (EC). F-box and WD repeat domain containing 7 (FBXW7) reportedly regulates the polarization and migration of macrophages in a multitude of cancers. Our pre-existing bioinformatics predictions showed a negative association between FBXW7 and M2-TAM infiltration in EC. This study aimed to investigate the role of FBXW7 in M2 macrophage polarization in EC by regulating the MYBL2/CCL2 axis. Cancer and adjacent cancerous tissues from patients with EC were collected to detect the differential expression of each factor. CCL2 levels in the Cell Culture medium were examined using enzyme-linked immunosorbent assay. Immunofluorescence staining was performed to determine the localization of FBXW7 and MYBL2 in EC cells. The number of M2 macrophages marker was determined by flow cytometry. The protein levels of FBXW7, MYBL2, CCL2, CD206, CD163, Arg1, and IL-10 were assessed using western blotting. The ubiquitination level of MYBL2 and the binding relationship between FBXW7 and MYBL2 were verified using co-immunoprecipitation. The effect of FBXW7/MYBL2/CCL2 axis on the malignant progression of EC in vivo was evaluated using tumor xenografts in nude mice. FBXW7 levels were decreased, whereas MYBL2 levels were increased in EC. Overexpression of FBXW7 downregulated CCL2 secretion in EC and inhibited M2 macrophage polarization. FBXW7 promoted the degradation of MYBL2 in a ubiquitination-dependent manner. FBXW7 knockdown inhibited CCL2 secretion by EC cells to restrain M2 macrophage polarization, which was countered by MYBL2 downregulation. In vivo functional assays demonstrated that FBXW7 overexpression significantly suppressed EC xenograft growth and enhanced tumor cell Apoptosis. FBXW7 enhanced the ubiquitination and degradation of MYBL2 to reduce CCL2 secretion from EC, which inhibited macrophage polarization to the M2 type.

Endometrial cancer; FBXW7; M2 macrophages; MYBL2; Ubiquitination.