Purification of a high molecular weight form of epidermal growth factor from urine of breast cancer patients.

A high molecular weight form of epidermal growth factor (EGF) was detected by means of an EGF radio-receptor assay and an anchorage-independent growth assay in the urine of breast cancer patients. Preliminary data indicate that the activity of this growth factor is associated with lymph node status and tumor size and that the activity becomes reduced after removal of the primary tumor. The EGF-related polypeptide was purified to homogeneity by a combination of Sephadex G-25 and Bio Gel P-30 chromatography followed by binding to, and elution from, EGF receptor rich A431 cells. Final purification was achieved after isoelectric focusing by following the biological activity of eluted polypeptides. A polypeptide of a pI of 3.4 was identified to carry EGF-like activity. This polypeptide migrated as a single band of 43 kDa in SDS-PAGE. Its biological activity was neutralized by a specific anti-hEGF-antibody indicating an immunological relationship with hEGF.