Immunopurification, characterization, and nature of membrane association of human melanoma-associated oncofetal antigen gp87 defined by monoclonal antibody 140.240

Prognostic value of a novel circulating serum 90K antigen in breast cancer

Monoclonal antibody SP-2 to the tumour-associated antigen 90K was generated by immunisation with conditioned medium of human breast cancer cells. We investigated whether circulating levels of 90K can influence the prognosis of patients with breast cancer. Serum samples were obtained from 425 patients with histologically proven breast cancer with no clinical evidence of disease after surgery (NED) and in 310 patients with metastatic disease. Serum 90K was determined by a new immunoradiometric assay (IRMA). Antigen levels in NED patients were elevated in 18.5% of cases, mean levels being higher than in healthy controls (P = 0.001). Among 375 evaluable patients, the 75-month overall survival for 90K-negative (< or = 11 U ml-1) and 90K-positive (> 11 U ml-1) patients was 78% and 53% respectively (P = 0.004). The prognostic value of 90K appeared to be limited to patients with node-positive disease. Number of metastatic axillary lymph nodes and level of 90K antigen were the only independent variables for predicting overall survival. Patients with metastatic breast cancer had elevated 90K in 51.3% of cases. High 90K levels were significantly associated with the presence of metastases to liver, shorter disease-free interval and younger age. We conclude that an elevated 90K antigen level in serum is a predictor of poor prognosis in breast cancer.

Purification and characterization of a 90 kDa protein released from human tumors and tumor cell lines

A novel tumor-associated protein, termed 90K, and recognized by mAb SP-2 was purified from serum of breast cancer patients, ovarian cancer ascitic fluid and conditioned medium of human breast cancer cells. In these three sources, native 90K is present as a high molecular weight complex that was dissociated by SDS-PAGE into a major band of approximately 90,000 Da. On the basis of electrophoretic mobility, buoyant density value, amino acid composition, and immunoreactivity, the 90K from the different sources appeared to be identical. NH2-terminal amino acid sequence revealed no homology to known protein.

Selective extraction by 1-butanol of surface glycoprotein antigens from human melanoma cells

The butanol extraction method has previously been used to achieve selective release of tumor-specific transplantation antigens from mouse sarcoma cells. In this study we investigated the feasibility of this method for extracting four surface glycoprotein antigens (87K, 95-150K, HLA-DR, and HLA-A,B,C) from cultured human melanoma cells. Of the four antigens examined, only 95-150K and HLA-DR antigens could readily be detected in material extracted by 2%, 3%, or 5% butanol. The 3% butanol was found to be most effective in releasing these two antigens. Treatment of melanoma cells with less than or equal to 3% butanol did not decrease the viability of extracted cells as judged by either Trypan Blue dye exclusion or plating efficiency. Thus the noncytolytic butanol extraction method offers a promising approach to the isolation of certain glycoproteins such as 95-150K and HLA-DR from viable human melanoma cells for further purification and structural analysis.