塩基性線維芽細胞成長因子(Basic Fibroblast Growth Factor : bFGF)過剰GH_3細胞の樹立とその株における形態および内分泌機能上の変化

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Basic fibroblast growth factor (bFGF) is a potent mitogen for various cells. In order to clarify the role of bFGF in the pituitary tumor cell functions, rat bFGF cDNA was fused to the promoter SR α, consisting of the early promoter of SV40 and HTLV (I)-LTR, and cotransfected with pSV2-neo to GH_3 cells by an electroporation method. After selection by G418, we obtained 7 neomycin resistant clones. Southern blot analysis of genomic DNA revealed the presence of transfected rat bFGF cDNA in 4 of 7 clones. We also established the immunofluorometric assay system for bFGF measurement using 3 monoclonal antibodies against different portions of human bFGF, which gave minimum detectable quantity of 10 pg / ml and cross-reacted neither with acidic FGF nor IGF-I within 100ng / ml. Though bFGF was undetectable in culture medium of any clones, cell contents of bFGF was 7.2ng/mg protein in 1 of 4 bFGF-transfected clones (GH_3FGF (+) ), whereas bFGF contents of parent GH_3 cells and the control cells transfecting only with pSV2-neo but not with bFGF cDNA (GH_3FGF (-)) were below 5.2pg/mg protein. GH_3FGF (+) grew as adherent cells and formed epithelial sheets. The amounts of PRL release by TRH was greater in GH_3FGF (+) than that in GH_3 or GH_3FGF (-). On the other hand, the sensitivity to SRIF was increased in Gfj:sFGF (+) compared with that in other clones. Transplantation of GH_3FGF (+) as well as GH_3 cells to Wister/Furth female rats resulted in the formation of tumor mass, which contained the enlarged capillary arteries and wider interstitium in GH_3 FGF (+ )-transplants than in GH_3. In this study we established for the first time the GH_3 cell clones overexpressing bFGF, and found the unique morphological and endocrinological changes in these cells probably attributable to overexpressed bFGF.

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