Abstract
We have established serum-free culture system for normal epithelial cells and cancer cells derived from oral mucosa and the salivary gland. It was found that oral cancer cells were able to grow in a serum-free medium supplemented with insulin, transferrin, sodium selenite, 2-aminoethanol and 2-mercaptoethanol disignated RD5F as same as that in the medium supplemented with 10% FBS. On the other hand, normal epithelial cells were not able to grow in a serum-free medium supplemented with factors as above. Thus hormone and growth factor requirement for proliferation of normal epithelial cells were studied in a serum-free medium. It was revealed that normal epithelial cells absolutely required EGF or FGF for the growth in a serum-free culture. Furthermore, we have studied effects of. EGF and FGF on the growth of oral cancer cells in a serum-free culture and expression of these factor receptors on the cell by radioligand receptor assay.
EGF stimulated growth of adenocarcinoma cells derived from the salivary gland (SAC) but inhibited that of squamous cell carcinoma (SCC) cells at the concentration which stimulate growth of other cells. FGF stimulated growth of SAC but did not have any effect on SCC cells. Furthermore, we could not find any significant differences in the expression of EGF and FGF receptors of these cells. Taken together, it was revealed that oral cancer cells exhibited lowered or lost requirement of EGF and FGF for growth compared to normal epithelial cells. These results strongly suggested the possibility that EGF and/or EGF receptor expressed in SCC cells were functionally different from that of normal epithelial cells.
