ABSTRACT
The manner of establishment of cell lines can be classified into three groups: spontaneous immortalization of normal cells, high-frequency immortalization of cells derived from malignancies, and immortalization by transformation, either by chemical carcinogens or oncogenic viruses. The introduction of oncogenes into cells has become a popular method of obtaining immortalized cell lines because the immortalization mechanism is clear. Like normal chondrocytes, proteoglycan synthesis in HCS-2/8 cells is stimulated by insulin and transforming growth factor(TGF)-ß. Basic fibroblast growth factor (bFGF) and retinoic acid which decrease proteoglycan synthesis in normal chondrocytes, also decrease proteoglycan synthesis in HCS-2/8 cells. The src and myc oncogene products inhibit different stages of differentiation of chondrocytes. This suggests the possibility of obtaining immortalized chondrocytes which retain the phenotype of a specific stage of differentiation by using src, myc, or other oncogenes to transform the cells and then investigate specific gene expression at each stage of chondrocyte differentiation.
