mRNA of MUC2 is stimulated by IL-4, IL-13 or TNF-α through a mitogen-activated protein kinase pathway in human colon cancer cells

MUC2 mucin is a secretory glycoprotein which is produced from the intestinal goblet cells and is a major component of the intestinal epithelial mucus. The biological function of MUC2 mucin is considered to be the protection of intestinal epithelial surface, whereas the regulatory mechanism of MUC2 mucin production in immune response is not completely understood. We have studied the effects of cytokines, IL-4, IL-13 and TNF-alpha, on the regulation of MUC2 mRNA in the human colonic cancer cell lines, LS174T and HT29. The quantitative reverse transcription-polymerase chain reaction showed that single addition of IL-4, IL-13 and TNF-alpha to cell culture induced about two-fold increase of MUC2 mRNA level in LS174T cells. Interleukin-4 and IL-13 activated phosphorylation of mitogen-activated protein kinase in LS174T cells. A specific inhibitor of mitogen-activated protein kinase pathway, U0126, totally inhibited the increase of MUC2 mRNA by IL-4 or IL-13 in those cells. Therefore, mitogen-activated protein activation of kinase is required for the increase of MUC2 mRNA by IL-4 or IL-13 in LS174T cells. In contrast to LS174T cells, only TNF-alpha increased MUC2 mRNA through a mitogen-activated protein kinase pathway in HT29 cells that express low levels of MUC2 mRNA. These findings sustain a novel phenomenon that MUC2 mRNA expression is differently controlled by IL-4, IL-13, or TNF-alpha in LS174T and HT29 cells, whereas the mitogen-activated protein kinase pathway plays a role in the MUC2 mRNA expression induced by those cytokines in both cell lines.