Identifying the factors and signal pathways necessary for anchorage-independent growth of Ha-ras oncogene-transformed NIH/3T3 cells.
Ha-ras(Val 12) overexpression was positively correlated with colony formation by NIH/3T3 derivative "2-12" cells harboring an inducible Ha-ras(Val 12) transgene. The ras-farnesylation inhibitor, Lovastatin, completely suppressed colony formation at higher dosages. However, Ha-ras oncogene overexpression alone could not stimulate colony formation under serum-deprived conditions, suggesting that ras is required but not sufficient for supporting colony formation. Substituting cow colostrum (AC-2) for serum did not result in colony formation from 2-12 cells in soft agar, suggesting the colostrum lacked or contained insufficient amounts of factors that stimulate colony formation. Supplementation of AC-2-containing medium with growth factors, such as insulin-like growth factor-1 (IGF-1), partially restored the capability of anchorage-independent cell growth induced by Ha-ras overexpression. Consistently, antibodies specific for IGF-1 receptors only partially blocked colony formation from 2-12 cells. The data indicate that multiple factors, including IGF-1, are required for Ha-ras-dependent colony formation. Signal transduction studies revealed that, under Ha-ras overexpression conditions, IGF-1 utilizes phosphatidyl inositol 3-kinase and NF-kappaB to transduce colony formation-related signaling.
Chang
Tsuey-Yu
TY
Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.
Tsai
Wen-Jiuan
WJ
Chou
Chao-Kai
CK
Chow
Nan-Haw
NH
Leu
Tzeng-Horng
TH
Liu
Hsiao-Sheng
HS
D016475:3T3 Cells; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D002417:Cattle; D002448:Cell Adhesion / Q000235:genetics; D002461:Cell Line, Transformed; D003126:Colostrum / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation; D011905:Genes, ras; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology / Q000502:physiology*; D008148:Lovastatin / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011247:Pregnancy; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000276:immunology; D015398:Signal Transduction; D019076:Transgenes
D019138:Antibodies, Blocking; D016328:NF-kappa B; D007334:Insulin-Like Growth Factor I; D008148:Lovastatin; D019869:Phosphatidylinositol 3-Kinases; D017526:Receptor, IGF Type 1; D016283:Proto-Oncogene Proteins p21(ras)