類胰島素生長因數對細胞增殖作用之影響

Abstract

中文摘要： 已知許多生長因數，具有控制細胞增殖活動之功能（ 1 －5 ）。本論文以類胰島素生長因數促進 Balb / c 3T3 細胞增殖之作用，進一步瞭解 IGF－1 作用在細胞週期中，使得靜止期細胞（ quiescent cells ）回復到 S 期（ DNA 生成），活化 immediate－early gene 之表現。 構築反順序 c－jun DNA 質體，將其送入細胞內，經過篩選（ 6 ) ，找到被引入質體的細胞株（ transfected clones ) 。 由南方點墨分析（ Southern analysis ) ，確定反順序 c－jun DNA 插入細胞的 genomic DNA 內。由北方點墨分析（ Northern analysis ) ，確定反順序 c－jun 核糖核酸在這些細胞株中被表現，可能阻止細胞內 c－jun蛋白質的正常轉譯作用（ 7－9 ） 。進一步挑出二個細胞株，發現此類細胞降低了對IGF-1 促進增殖作用之反應，細胞內正常c－jun 基因之表現，也減少了。 比較 12－0－tetradecanoyl－Phorbo1 13－acetate ( TPA ) ( 10 ) , dexamethasone ，－種合成的類皮質塘荷爾蒙（ 11 ) 等直接或間接作用在 c－jun 基因起動子（ promoter ）影響其基因表現之程度，推測IGF-1 生長因數活化 c－jun 基因表現作用機制，是藉由細胞內產生信號（ signal ） 作用在c－jun 基因起動子上。

Abstract Growth factors play essential roles in the regulation of cells’ growth. In this study, I examined the growth promotion effect of insulin like growth factor 1 (IGF-1) with quiescent Balb/c 3T3 cells. Data from Northern analyses indicated that the expression level of c—jun induction seems to be primary response, since the addition of cycloheximide and IGF-1 together cannot suppress the expression. To investigate the relationship between IGF—1, c—jun and cell proliferation, an expression vector with antisense c—jun (c—nuj) transcript was transfected to Balb/c 3T3 cells. Twenty stable transfectants were isolated. Two of them (Bi, B5) alter the responses to IGF-1, both growth promotion and c—jun induction. The other clones are under characterization now. Normally, dexamethasone (a synthetic glu — cocorticoid hormone) shows inhibition effects on c—jun transcription. In the presence of IGF—1, the inhibition of c—jun by dexamethasone, however, can be overcome. These together suggest that the induction of c-jun b IGF-1 may be due to transcriptional control. Induction seems to be primary response, since the addition of cycloheximide and IGF-1 together cannot suppress the expression. To investigate the relationship between IGF—1, c—jun and cell proliferation, an expression vector with antisense c—jun (c—nuj) transcript was transfected to Balb/c 3T3 cells. Twenty stable transfectants were isolated. Two of them (B1, B5) alter the responses to IGF-1, both growth promotion and c—jun induction. The other clones are under characterization now. Normally, dexamethasone (a synthetic glu — cocorticoid hormone) shows inhibition effects on c—jun transcription. In the presence of IGF—1, the inhibition of c—jun by dexamethasone, however, can be overcome. These together suggest that the induction of c-jun by IGF-1 may be due to transcriptional control.