Progression and Metastasis of Mammary Carcinomas: Potential Role of the Muc-1 Clycoprotein.

MUCi is a large heavily glycosylated membrane mucin glycoprotein which is overexpressed and aberrantly glycosylated by the majority of caricnomas and in particular, by 92 of primary and metastatic breast cancers. It is hypothesized that overexpression of the MUC 1 protein by carcinoma cells may confer an advantage upon the cell, perhaps by reducing the adhesive properties of cells andor by modulating the immunogenicity of the tumor cells. Mice homozygous for the null mutation are healthy, fertile and do not display any obvious pathology. However, Muc-l deficient mice demonstrate significantly slower growth of polyoma vims middle T antigen induced mammary tumors compared with wild type controls. Depletion of NK cells did not result in significant changes in mammary tumor growth rate in either Muc-l deficient or wild type mice, but genetic background of the mice complicated evaluation of the study. Overall, these data demonstrate for the first time that Muc- I expression can significantly affect the growth of breast cancer cells.