IL6 stromal expression is correlated with epithelial–mesenchymal transition at tumor budding in colorectal cancer

Background: Tumor budding (TB) is a poor prognostic factor in colorectal adenocarcinoma (CA), but the underlying mechanism remains unclear. Interleukin-6 (IL6) is one of the main cytokines produced by cancer-associated fibroblasts. IL6 is linked with cancer progression and poor prognosis by activating cancer cells and modifying the cancer microenvironment. However, little is known about the expression of IL6 in TB and its association with TB in CA. Methods: The clinicopathological and prognostic significance of IL6 in TB was examined using a tissue microarray consisting of 36 patient samples of TB in CA. IL6 mRNA was detected by RNAscope. Patients were stratified into negative and positive IL6 expression groups. Results: : IL6 expression was overwhelmingly observed in cancer stroma but was negligible in cancer cells. In the IL6 -positive group in cancer stroma, TB grade was higher than in the IL6- negative group ( P =0.0161). The IL6 -positive group significantly exhibited the epithelial–mesenchymal transition (EMT) phenotype compared with the IL6- negative group in cancer stroma ( P =0.0301). There was no significant difference in overall survival between CA cases in the IL6 -positive and -negative groups in cancer stroma. Conclusions: : TB may be affected by IL6 expression, and IL6 expression in cancer stroma at TB may be an important prognostic marker.