Comparison of MUC-1 mucin expression in epithelial and non-epithelial cancer cell lines and demonstration of a new short variant form (MUC-1/Z).
Mucins, including MUC-1, are generally considered to be products of epithelial tissues and of their tumors. To examine the possible expression of MUC-1 in other cell types, a panel of human epithelial and non-epithelial tumor cell lines was studied by reverse transcriptase polymerase chain reaction (RT-PCR), Northern blot analysis, immunocytology and radioimmunoprecipitation. Using the highly sensitive RT-PCR method, products corresponding to the non-repetitive 5' and 3' MUC-1 sequences were detected in all the cell lines examined. Amplified products lacking the tandem repeat region of MUC-1, including a new short form (designated MUC-1/Z) different from the previously reported MUC-1/Y protein, were also detected in most cell lines tested. Northern blot analysis, using a probe to the variable number tandem repeat (VNTR) region, confirmed the presence of MUC-1 mRNA in the astrocytoma, melanoma and neuroblastoma cell lines studied. MUC-1 protein was detected by immunocytology in these cell lines using monoclonal antibody (MAb) 139H2. Immunoprecipitation analysis with [3H]-glucosamine-labeled cell lysates and MAb 139H2 or an antibody to the cytoplasmic domain, CT-1, detected MUC-1 protein in 2 epithelial cell lines, an astrocytoma cell line (SK-MG-4) but not in the melanoma and neuroblastoma cell lines studied. Northern blot analysis using a probe to the 3' end of MUC-1 mRNA, confirmed the presence of MUC-1 mucin and also identified short products corresponding to the size of the short variant forms. Protein products corresponding to the MUC-1/Y and MUC-1/Z variant forms were not observed using either [3H]-glucosamine-labeled OVCAR-3 cells or [3H]-amino acid-labeled MCF-7 cells and either CT-1 antibody or MAb 232A1, detecting an epitope to the C-terminal region. Thus, depending on the sensitivity of the assay used, varying amounts of MUC-1 mRNA and protein could be detected in non-epithelial tumor cell lines. Although the amounts of MUC-1 in these cell lines are much lower than in carcinomas, it is possible that MUC-1 mucin serves a similar function in non-epithelial as in epithelial cells. The possible role of MUC-1/Y and MUC-1/Z variant forms in these cell lines is not understood.
Oosterkamp
H M
HM
Gynecology Service, Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Scheiner
L
L
Stefanova
M C
MC
Lloyd
K O
KO
Finstad
C L
CL
D001254:Astrocytoma / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D001943:Breast Neoplasms / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism; D008969:Molecular Sequence Data; D018396:Mucin-1 / Q000378:metabolism*; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured
D018396:Mucin-1; D009077:Mucins; D009363:Neoplasm Proteins; D012333:RNA, Messenger