Th22 cell accumulation is associated with colorectal cancer development

AIM: To investigate the expression of Th22 cells and related cytokines in colorectal cancer (CRC) tissues, and the probably mechanism. METHODS: CRC tumor and paratumor tissues were collected to detect the expression levels of Th22 cells and of related cytokines by immunohistochemistry, flow cytometry and real-time quantitative polymerase chain reaction (RT-qPCR). interleukin (IL)-22 alone or with a STAT3 inhibitor was co-cultured with RKO cells in vitro to study the effects of IL-22 on colon cancer cells. IL-22 alone or with a STAT3 inhibitor was injected into a BALB/c nude mouse model with subcutaneously transplanted RKO cells to study the effects of IL-22 on colon cancer growth. RESULTS: The percentage of Th22 cells in the CD4(+) T subset was significantly higher in tumor tissues compared with that in paratumor tissues (1.47% +/- 0.083% vs 1.23% +/- 0.077%, P < 0.05) as determined by flow cytometry. RT-qPCR analysis revealed that the mRNA expression levels of IL-22, aryl hydrocarbon receptor, CCL20 and CCL22 were significantly higher in tumor tissues compared with those in paratumor tissues. CCL27 mRNA also displayed a higher expression level in tumor tissues compared with that in paratumor tissues; however, these levels were not significantly different (2.58 +/- 0.93 vs 2.30 +/- 0.78, P > 0.05). IL-22 enhanced colon cancer cell proliferation in vitro and displayed anti-apoptotic effects; these effects were blocked by adding a STAT3 inhibitor. IL-22 promoted tumor growth in BALB/c nude mice; however, this effect was reversed by adding a STAT3 inhibitor. CONCLUSION: Th22 cells that accumulate in CRC may be associated with the chemotactic effect of the tumor microenvironment. IL-22 is associated with CRC development, most likely via STAT3 activation.