PURIFICATION OF A CELL-GROWTH FACTOR FROM A HUMAN LUNG-CANCER CELL-LINE - ITS RELATIONSHIP WITH FERRITIN

We have purified a cell growth factor from a human lung cancer cell li ne, T3M-30, which was established in a protein-free chemically defined medium. The factor, designated carcinoma-derived growth factor (CD-CF ), stimulated proliferation of a variety of cells, including human leu kemia cells, HL-60, and melanoma cells, SK-28. Half-maximum stimulatio n by the purified CD-CF was achieved at a concentration of 40 ng/ml. I n the purified CD-CF, two major protein bands of 24 kDa and 22 kDa wer e identified on a SDS polyacrylamide gel. The partial amino acid seque nces of the 24 kDa protein were determined from two peptide fragments obtained by V8 protease treatment. The partial sequences were identica l to those of heavy chain of human ferritin. The activity of the purif ied CD-GF was coprecipitated completely with a monoclonal antibody to heavy chain of ferritin. Ferritin has been considered to inhibit cell growth. However, human heart ferritin was capable of stimulating the g rowth of HL-60 cells. These results suggest that CD-GF is related to f erritin and ferritin is a growth factor of HL-60 leukemia cells. (C) 1 994 Wiley-Liss, Inc.