K. Ryuko et al., Characterization of a new MUC1 monoclonal antibody (VU-2-G7) directed to the glycosylated PDTR sequence of MUC1, TUMOR BIOL, 21(4), 2000, pp. 197-210
A monoclonal antibody (MAb), VU-2-G7, was generated against a synthetic 60-
mer MUC1 triple tandem repeat peptide with N-acetyl-galactosamine (GalNAc)
O-linked to the threonine in the PDTR region of each repeat (3M GalNAc). VU
-2-G7 and 8 MUC1 MAbs (VU-3-C6, VU-4-H5, 139H2, A76-A/C7, VU-12-E1, BCP9, M
F11 and BW835) were tested against various glycosylated and nonglycosylated
MUC1 tandem repeat peptides. VU-2-G7 showed strong reactivity with its imm
unogen, 3M GalNAc, and much lower reactivity with the nonglycosylated 60-me
r MUC1 triple tandem repeat peptide. VU-2-G7 showed no reactivity with a 60
-mer MUC1 triple tandem repeat peptide modified at the PDTR region or with
a 60-mer MUC1 triple tandem repeat peptide with 3 GalNAc per repeat outside
the PDTR region (9M GalNAc). In ELISA and flow cytometry, VU-2-G7 ubiquito
usly reacted with 4 MUC1-expressing breast cancer and 2 ovarian cancer cell
lines and with a MUC1-gene-transfected Chinese hamster ovary cell line. Th
e reactivity of VU-2-G7 was always higher than that of VU-4-H5, raised agai
nst a nonglycosylated 60-mer MUC1 triple tandem repeat peptide. Immunohisto
chemical staining of paraffin sections of breast and ovarian tumor tissues
showed strong binding of VU-2-G7 predominantly at the cell membrane. The do
minant epitope of VU-2-G7 is in the glycosylated PDTR motif of the MUC1 tan
dem repeat, and this epitope is abundantly present on the surface of tumor
cell lines and breast and ovarian tumor tissues. Given the ubiquitously abe
rrant glycosylation of MUC1 in malignant cells, the production of MAbs agai
nst highly purified glycosylated MUC1 tandem repeat peptides may yield MAbs
better suited for the immunotherapy of carcinomas than those available at
the moment. Copyright (C) 2000 S. Karger AG, Basel.