MAUB is a new mucin antigen associated with bladder cancer.
The M344 tumor-associated antigen, expressed in 70% of superficial bladder tumors, is a sialylated carbohydrate present on a high molecular mass thiol-reducible secreted mucin, which we named MAUB for mucin antigen of the urinary bladder. Herein we studied the relationship between MAUB and other known mucins in the MGH-U3 bladder cancer line where MAUB expression is modulated by culture conditions. Northern blots, immunoradiometric assays, and Western blots showed that only MUC1 and MUC2 are expressed in this MAUB-positive cell line. MUC1 differs from MAUB by its molecular mass and its non-oligomeric nature, while MUC2 has similar molecular mass and response to culture conditions. However, in double determinant immunoradiometric assays, MAUB and MUC2 did not cross-react. Moreover, confocal microscopy showed different subcellular localization of the two antigens. Treatment of MGH-U3 cells with MUC2 antisense oligodeoxynucleotides resulted in decreased expression of MUC2 and increased expression of MAUB, ruling out the possibility that monoclonal antibody M344 recognizes a different glycosylated form of MUC2. In addition, we identified a tumor specimen expressing MAUB but no MUC2 antigen or mRNA. Together, these results suggest that there is expression of at least three mucins in MGH-U3 cells and that MAUB is a cancer-associated mucin distinct from those identified so far.
Bergeron
A
A
Laboratoire d'Uro-Oncologie Expérimentale, Centre de recherche de l'Hôtel-Dieu de Québec, 11 côte du Palais, Québec, Canada G1R 2J6.
Champetier
S
S
LaRue
H
H
Fradet
Y
Y
D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D018076:DNA, Complementary; D000939:Epitopes; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009077:Mucins / Q000235:genetics / Q000276:immunology*; D010212:Papilloma / Q000276:immunology* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000276:immunology* / Q000473:pathology
D000951:Antigens, Neoplasm; D018076:DNA, Complementary; D000939:Epitopes; D009077:Mucins; D012333:RNA, Messenger