Although the loss of
sulfomucins was known as an
indicator of
carcinogenesis and malignant progression of colonic epithelia, it was not known whether the loss was directly related to the malignant behavior of colon
carcinoma cells. We have studied the
biological properties of LS174T human colon
carcinoma cells before and after suppression of
sulfomucin production. Incorporation of [35S]-
sulfate into high molecular weight
mucins decreased after
carcinoma cell treatment with 1.5%
dimethylsulfoxide (
DMSO) for 8 days. The amounts of
sulfomucin determined using a
sulfomucin-specific
monoclonal antibody (mAb 91.9H), in Western blot and flowcytometric analyses, also decreased. In addition, the levels of MUC2 and MUC5B
mucin gene expression measured by RT-PCR were reduced after
DMSO-treatment, whereas the levels of MUC1, MUC5AC, and MUC6
mucin gene expression were not. The
DMSO-treated cells were tested in vitro and in vivo for their properties. Differences were not detected in their anchorage-independent growth, anchorage-dependent growth,
E-selectin-dependent cell adhesion or sensitivity to
interleukin (IL)-2-activated lymphocyte cytolysis. When untreated or
DMSO-treated LS174T cells were injected intrasplenically into nude mice, the treated cells lacking certain cell surface
sulfomucins formed fewer metastatic colonies in the liver. These results suggest that the loss of
sulfomucins by colonic epithelial cells during progression is not directly related to the enhanced malignant behavior.