Modulation of Growth and Transformation of Murine MC3T3-E1 Cell Line by Murine Wild-type and Mutant p53 Genes

We studied the effects of murine wild-type and mutant p53 genes (p53-wt and p53val135) on the growth and transformation of murine osteoblastoid cell line MC3T3-El. The mutant p53val135 enhanced focus formation of MC3T3-E1 cells by the activated H-ras plus LTR-myc gene and H-ras plus adenovirus 12 E1A gene more than four fold each, while p53-wt suppressed them 0.4 and 0.3 fold, respectively. The plating efficiency of hygromycin-resistant MC3T3-E1 cells after transfection of pSV2hygro were also increased by more than three fold with the cotransfection of p53val135 and the efficiency was also decreased 0.2 fold by cotransfection of p53-wt. These indicate that p53val135 enhances and p53-wt suppresses not only oncogene focus formation but also the cellular growth of the murine MC3T3-E1 cell line. Southern blot hybridization detected the tran-sfected p53-wt sequence only in three out of ten MC3T3-E1 cell lines established from foci induced by p53-wt and oncogenes, and failed to detect the p53-wt DNA in hygromycin-resistant MC3T3-E1 cell lines transfected with pSV2hygro and p53-wt. These suggest that MC3T3-E1 cells containing p53-wt are at a dis-advantage to form transformed foci or colonies, and suggests that MC3T3-E1 provides a good in vitro system to test the biological activity of murine wild-type and mutant p53 genes