Re-transformation of non-transformed hybrids between c-myc-activating mouse plasmacytoma cells and normal fibroblasts by transfection with activated c-Ha-ras but not c-myc.
In a mouse plasmacytoma S194, c-myc oncogene is rearranged with Ig gene by chromosomal translocation and is consequently activated. We previously reported that transformation of phenotype and expression of rearranged c-myc were repressed in independently isolated hybrid clones, I-1 and IV-10, between S194 and normal fibroblasts. In order to investigate the relationship between transformation of phenotype and oncogene expression, transcriptionally enhanced c-myc or activated c-Ha-ras was transfected into I-1 or IV-10I, a subclone of IV-10. Transfectants expressing high levels of c-myc were found to retain the non-transformed phenotypes. On the other hand, transfectants expressing activated c-Ha-ras showed the transformed phenotypes. These results suggest that enhanced expression of c-myc is not sufficient for re-transformation of the non-transformed hybrid clones between c-myc-activating plasmacytoma cells and normal fibroblasts, but expression of activated c-Ha-ras could diminish or overcome the tumor-suppressive activity of normal fibroblasts.
Cancer Institute, Hokkaido University School of Medicine, Sapporo, Japan.
C
C
Satoh
T
T
Oikawa
N
N
Kondoh
N
N
Kuzumaki
D000818:Animals; D002461:Cell Line, Transformed; D005347:Fibroblasts / Q000473:pathology*; D005786:Gene Expression Regulation; D016259:Genes, myc; D011905:Genes, ras; D006822:Hybrid Cells / Q000473:pathology*; D051379:Mice; D010641:Phenotype; D010954:Plasmacytoma / Q000235:genetics / Q000473:pathology*; D014162:Transfection