[Role of growth factors in the autonomous growth of tumor cells].
Typical characteristic of tumor cells is a decreased dependence on the growth factors for promotion of their growth. Growth factor independence and autonomous growth of tumor cells has been thought to be due to the ability of the cells to produce growth factors. According to an autocrine hypothesis, growth factor can be secreted by tumor cells and then binds to its receptor on the same cells to create an uncontrolled growth stimulation. Although there has been much circumstantial evidence to support this hypothesis, an autocrine mechanism is still uncertain. We purified DSF (DNA synthesis factor) from an extract of rat Rhodamine fibrosarcoma. This factor with strong affinity for heparin-Sepharose was a basic protein with molecular weight of 17,000. These properties were similar to those of basic FGF (fibroblast growth factor). We found that primary cells from the sarcoma could grow in serum-free medium supplemented with the extract of the same sarcoma tissue. The extract was fractionated to purify proteins which supported the growth of primary cells. DSF, transferrin and albumin which localized in the tissue, not due to contamination of blood, were purified. When they were added to the serum-free medium, the cells grew at a similar rate to that in medium supplemented with serum. This finding suggests that the growth of sarcoma cells is stimulated by their own growth factor and by some environmental factors.
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D005346:Fibroblast Growth Factors / Q000502:physiology*; D005354:Fibrosarcoma / Q000473:pathology; D006133:Growth Substances / Q000502:physiology; D006493:Heparin / Q000502:physiology; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification / Q000502:physiology*; D051381:Rats; D012513:Sarcoma, Experimental / Q000473:pathology*; D015291:Transforming Growth Factors
D006133:Growth Substances; D010455:Peptides; D005346:Fibroblast Growth Factors; D015291:Transforming Growth Factors; D006493:Heparin