[11] Separation of melanoma growth stimulatory activity and human Type-α transforming growth factor

Publisher Summary Melanoma growth stimulatory activity (MGSA) is a monolayer mitogen for cultured nevus cells and malignant melanoma cells. This growth factor is produced by the Hs0294 human melanoma cell line and is associated with the serum-independent proliferation of these cells in culture. MGSA is an acid- and heat-stable polypeptide that is sensitive to trypsin and dithiothreitol. The activity differs from the transforming growth factors (TGFs) of the TGFα type that are produced by human melanoma cells in that MGSA stimulates anchorage-dependent growth of melanoma and nevus cells but does not enable normal rat kidney (NRK) indicator cells to exhibit anchorage-independent growth as TGFα does. Epidermal growth factor (EGF) acts through the same receptor as TGFα but has no effect on the [ 3 H]thymidine incorporation into Hs0294 cells. MGSA can be purified from acetic acid extracts of serum-free conditioned medium (CM) from the Hs0294 cell line by BioGel P-30 chromatography, followed by reversed-phase high-pressure liquid chromatography (RP-HPLC) on a μBondapak C 18 column. When purified in this manner, the major peak of MGSA activity elutes at 35±3% of acetonitrile just following the I-labeled EGF competing TGFα peak that elutes at 30±4% of acetonitrile.