Objective To investigate the role and mechanism on how M2 macrophages promote epithelial-mesenchymal transition (EMT) of bladder cancer cells via clauding10 (CLDN10)-mediated signaling pathway. Methods Ten pairs of fresh bladder cancer tissues and corresponding para-tumor tissues were collected in Chongqing University Cancer Hospital during March and September 2020. Immunohistochemical (IHC) assay was used to detect the expression of macrophages' membrane markers. The genes regulated by macrophages were screen out with transcriptome sequencing together with immune scores based on IHC assay in bladder tissues. CCK-8 assay, cellular colony and Western blotting were employed to observe the effect of CLDN10 on the growth and proliferation of bladder cancer cells. Results Macrophages' characteristic marker CD68 and M2 macrophages' CD163 were highly expressed in bladder cancer tissues. Gene sequencing indicated that CLDN10 was significantly expressed in the tumor tissues, and its expression was positively correlated with the infiltration of macrophages in bladder tissues. The Results of Western blotting showed that the CLDN10 expression were higher in cancer tissues compared to adjacent normal tissues (P < 0.05). Knockdown of CLDN10 decreased the growth ability of T24 cells and decreased the number of colonies than the untreated cells (198.0±10.3 vs 145.0±8.4, P < 0.05). Additionally, the protein levels of snail, twist and vimentin were significantly decreased, whereas that of Ecadherin was increased after CLDN10 knockdown. Conclusion Macrophages upregulate CLDN10 expression in bladder cancer cells, and thus promotes EMT and progression of the cancer cells.
