摘要
利用放射受体结合测定证明了两株人体肝癌细胞株7402和7721细胞均有EGF受体的存在。受体数目分别为每细胞6.2×10~4和2.5×10~4,代表它们亲和力的解离常数K_D值分别为1.2 nmol/L和0.80 nmol/L。PMA处理对7721细胞的EGF受体及其亲和力均无明显影响;对7402细胞EGF受体却显示了调变作用。受体数目虽同样没有变化;但亲和力却随药物处理时间有一个下降、恢复的变化过程。在PMA处理1小时,EGF结合抑制达最大,此时受体的解离常数K_D值为3.0 nmol/L;在处理96小时,受体亲和力恢复并略有增高,此时K_D值为0.95 nmol/L。~3H-TdR参入实验表明,在PMA抑制7402细胞EGF受体亲和力的同时,细胞DNA的合成速率也相应下降。对于佛波酯等因子对EGF受体的调变作用,我们认为是属于生长因子启动细胞DNA合成进行细胞分裂的整个生物学过程中感受性因子对进行性因子的调节作用。
Using radioligand binding assay,the pre-sence of epidermal growth factor(EGF) recep-tors in cells of two human liver cancer celllines,BEL-7402 and SMMC-7721,was de-monstrated.The ligand binding data wereanalyzed by a computer program.The disso-ciation constants (K_D) of the ligand-receptorbinding complex at equilibrium for 7402 and7721 cells were 1.2 nM and 0.8 nM respe-ctively,and their number of EGF receptorsper cell were 6.2×10~4 and 2.5×10~4 respecti-vely.After the treatment of cells with pho-rbol 12-myristate 13-acetate (PMA),no chan-ge either in the affinity or in the numberof EGF receptors was found in 7721 cells.However,in the case of 7402 cells,while thenumber of receptors,like 7721 cells,remainedunchanged,the affinity of EGF receptors dis-played a time dependent modulation afterPMA treatment.It dropped within the firsthour to a K_D value of 3.0 nM and thengradually returned to the normal controlvalue at 48 hours or even slightly higherthan normal (0.95 nM) at 96 hours of treat-ment.The modulation or down-regulation ofEGF receptors by PMA in 7402 cells wasparalleled by the simultaneous inhibition ofDNA synthesis in these cells as evidencedfrom their reduction of ~3H-TdR uptake.It isnot clear what is the basis for the differencesfound between 7402 cells and 7721 cells intheir number of EGF receptors per cell andtheir responsiveness to PMA treatment.Itmight be related to their difference in auto-crine secretion of a-transforming growth fac-tors.The effect of PMA on 7402 cells is,however,discussed in light of the competen-ce-progression model described by Pledgeret al.
出处
《实验生物学报》
CSCD
1989年第3期343-351,共9页
Acta Biologiae Experimentalis Sinica
关键词
人肝癌细胞
表皮生长因子
受体
Human liver cancer cell lines.Epidermal growth factor receptor.Phorbol 12-myristate 13-acetate (PMA).Modulation.
