THE HUMAN INTESTINAL-CELL LINES CACO-2 AND LS174T AS MODELS TO STUDY CELL-TYPE-SPECIFIC MUCIN EXPRESSION

Mucin expression was studied during proliferation and differentiation of the enterocyte-like Caco-2 and goblet cell-like LS174T cell lines. Caco-2 cells express mRNAs of MUC1, MUC3, MUC4 and MUC5A/C whereas MUC 2 and MUC6 mRNAs are virtually absent. Furthermore, MUC3 mRNA is expre ssed in a differentiation dependent manner, as is the case for enteroc ytes. Concomitantly MUC3 protein precursor (similar to 550 kDa) was de tected in Caco-2 cells. In LS174T cells mucin mRNAs of MUC1, MUC2 and MUC6 are constitutively expressed at high levels, whereas MUC3, MUC4 a nd MUC5A/C mRNAs are present at low levels. At the protein level LS174 T cells express the goblet cell specific mucin protein precursors MUC2 , MUC5A/C and MUC6 with apparent molecular masses of about 600 kDa, 47 0/500 kDa and 400 kDa respectively. MUC3 protein is not detectable. Fu rthermore, human gallbladder mucin protein (similar to 470 kDa precurs or), of which the gene has not yet been identified, is expressed in LS 174T cells. In addition, synthesis and secretion of the goblet cell sp ecific mature MUC2, MUC5A/C and human gallbladder mucin was demonstrat ed in LS174T cells. It is concluded that Caco-2 and LS174T cell lines provide excellent in vitro models to elucidate the cell-type specific mechanisms responsible for mucin expression.