Expression of a recombinant breast tumor-associated mucin fusion protein in Escherichia coli exposes the tumor-specific epitope.
Mucins are highly immunogenic glycoproteins that are abundantly expressed by breast carcinomas and other carcinomas. The fact that deglycosylated normal mucin can induce tumor-specific monoclonal antibodies indicates that tumor-specific epitopes are hidden in the fully glycosylated form. Using recombinant DNA techniques, a fragment of mucin tandem repeats was inserted into pMal-p, an Escherichia coli expression vector, and resulted in the expression of an unglycosylated maltose-binding protein-mucin fusion protein. This fusion protein has been purified and showed strong affinity to breast tumor-specific monoclonal antibody SM3. The antisera against this recombinant mucin fusion protein recognized all breast tumor cell lines we tested. Competition assay with monoclonal antibody SM3 shows that anti-recombinant mucin fusion protein binds the epitope that SM3 binds. These results confirm the hypothesis that unglycosylated mucin contains a tumor-specific epitope. This leads to the possibility that recombinant mucin may be used to develop vaccines against breast cancer and cytotoxic T-lymphocyte lines for immunotherapy of breast cancer.
Hu
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Department of Internal Medicine, Texas Tech University Health Sciences Center, Amarillo.
Wright
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D018528:ATP-Binding Cassette Transporters; D001943:Breast Neoplasms; D002352:Carrier Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008163:Luminescent Measurements; D058619:Maltose-Binding Proteins; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins; D009077:Mucins / Q000032:analysis / Q000096:biosynthesis* / Q000302:isolation & purification; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000302:isolation & purification; D014407:Tumor Cells, Cultured
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D009077:Mucins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli