[Molecular mechanism of androgen-dependent transformation--analysis using serum-free culture system].
SC-3 cells, derived from androgen-dependent mouse breast cancer Shionogi carcinoma 115, have shown not only androgen-dependent growth stimulation but also morphological changes in serum-free culture. We have demonstrated that this androgen-dependent growth is mediated through an induction of heparin-binding growth factor (termed as androgen-induced growth factor: AIGF). We studied the molecular mechanism of androgen-dependent growth. NIH3T3 cells transfected to express AIGF showed focus-forming activity, anchorage-independent growth and tumor formation in nude mice indicating AIGF is an oncogene. The findings that AIGF inhibited binding of [125I]basic fibroblast growth factor (bFGF) and only FGF receptor (FGFR)-1 mRNA expressed in SC-3 cells suggested that AIGF acts through FGFR-1. Therefore, we cloned FGFR-1 from cDNA library of SC-3 cells, which was found to have three mutations. When this variant FGFR-1 was expressed in FGFR-negative myoblast L6 cells, AIGF-dependent inhibition of the differentiation to myocytes was observed suggesting that variant FGFR-1 is receptor of AIGF. Since expressions of c-myc mRNA as well as AIGF mRNA were induced by testosterone treatment, we studied the role of c-myc in androgen-dependent growth in SC-3 cells using phosphorothioate derived antisense oligonucleotides (antisense) of c-myc or AIGF. Not only AIGF antisense but also c-myc antisense inhibited androgen-dependent growth. c-myc antisense did not affect androgen-induced AIGF mRNA expression. c-myc antisense inhibited AIGF-, but not bFGF-induced DNA synthesis. These results suggest that c-myc has a critical role of AIGF-, but not bFGF-induced growth.
Koga
M
M
Department of Medicine III, Osaka University Medical School, Japan.
Kouhara
H
H
Sato
B
B
D016475:3T3 Cells; D000728:Androgens / Q000502:physiology*; D000818:Animals; D016895:Culture Media, Serum-Free; D005260:Female; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000378:metabolism / Q000502:physiology; D016259:Genes, myc; D006133:Growth Substances / Q000502:physiology; D008325:Mammary Neoplasms, Experimental / Q000235:genetics / Q000473:pathology*; D051379:Mice; D009363:Neoplasm Proteins / Q000502:physiology; D009376:Neoplasms, Hormone-Dependent / Q000473:pathology*; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger / Q000378:metabolism; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D014170:Transformation, Genetic; D014407:Tumor Cells, Cultured
D000728:Androgens; D016895:Culture Media, Serum-Free; C496457:Fgf8 protein, mouse; D006133:Growth Substances; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors