A Mr 43,000 epidermal growth factor-related protein purified from the urine of breast cancer patients

A tumor-associated epidermal growth factor (EGF)-like activity was detected in the urine of breast cancer patients by means of an EGF radioreceptor assay and an anchorage-independent growth assay. The clonogenic growth factor activity of pooled void volume eluate fractions from a Bio-Gel P-30 column was completely neutralized by an anti-human epidermal growth factor antiserum but not by an anti-transforming growth factor alpha antiserum. This activity was determined in the urine of 71 breast cancer patients. A statistically significant correlation was found between EGF-like clonogenic activity and axillary lymph node status, tumor size, stage of disease, and grade of differentiation of the primary tumor. The Bio-Gel P-30 void volume fraction was used to purify the EGF-related polypeptide to apparent homogeneity by subsequent binding to and elution from A431 cells followed by isoelectric focusing. A polypeptide of a pI of approximately 3.4 was identified to be related to EGF by neutralization and immunoprecipitation experiments with anti-human epidermal growth factor antisera. This polypeptide migrated as a single band of Mr 43,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis.