MOUSE MUCIN-1 (MUC1) DEFINED BY MONOCLONAL-ANTIBODIES

Mucins are highly expressed in many different human cancers and numero us murine monoclonal antibodies (MAbs) to human mucins, particularly M ucin I (MUCI), have been produced. However, no such antibodies to muri ne mucin I (mucI) have been described and we now describe 6 different antibodies produced to murine mud and to human MUCI cytoplasmic tail, either by immunising rats, or mud o/o mice with synthetic peptides or a fusion protein composed of glueathione-s-transferase (GST) linked to the tandem repeat region of mucI. The antibodies to both the extracel lular tandem repeat region and to the cytoplasmic tail were found to r eact with mucin-containing murine tissues such as breast, stomach, col on, ovary, kidney and pancreas, and the staining patterns were similar to those found in humans. The reagents reacted specifically with mud peptides and tissues; however, some cross reactivity with other mucin- derived peptides was noted, particularly those containing the amino ac id sequence TSS. Three different epitopes (TSS, TAVLSGTS and LSGTSSP) of the M30, M70 and MFP25 MAbs were detected. Of interest was the find ing that some of the antibodies reacted with murine lymphocytes; it wa s not clear whether these reactions were due to mucin I on mouse lymph ocytes (MUCI was considered to be absent from human lymphocyte), or du e to cross reaction with a sialic adhesion molecule on lymphocytes. Th e antibodies should prove valuable reagents when studying differentiat ion and expression in murine glandular tissues and the ontogeny of muc in-secreting tumours. (C) 1998 Wiley-Liss, Inc.