胃肠道间质瘤相关PDGFRA基因突变体功能的研究

目的 探讨胃肠道间质瘤中一个新的PDGFRA基因突变位点L839P在肿瘤发生发展中的恶性转化作用.方法 采用脂质体法,将重组质粒稳定转染中国仓鼠卵巢上皮细胞(CHO).应用Western blot法,检测PDGFRA蛋白的表达情况.应用细胞计数法,描绘细胞生长曲线;应用流式细胞仪榆测细胞周期及细胞凋亡,并观察稳转突变型重组质粒CHO细胞在裸鼠体内的成瘤性.将PDGFRA突变型与kit野生型重组质粒共同瞬时转染CHO细胞,用Western blot法检测kit蛋白的表达及其磷酸化状态.结果 阴性对照组、实验组及阳性对照组细胞中均有PDGFRA蛋白表达.实验组和阳性对照组较阴性对照组和空白对照组细胞生长速度加快;空白对照组、阴性对照组、实验组和阳性对照组处于增殖期的细胞比例分别为28.4%、24.5%、43.8%和40.9%,凋亡率分别为1.8%、1.9%、1.5%和1.6%.接种阳性对照组及实验组稳转细胞的裸鼠,3周后均见肿瘤生长.PDGFRA突变型质粒与kit野生型质粒共转染CHO细胞后,磷酸化kit蛋白表达明显增强.结论 PDGFRA基因L839P点突变为功能获得性突变,对正常细胞有较强的恶性转化作用,并口丁激活kit蛋白,导致肿瘤发生.

Transforming effect of PDGFRA gene mutant on the cell function in gastrointestinal stromal tumor

Objective To explore the effect of malignant transformation of the L839P, a new mutation site of the PDGFRA gene, on the pathogenesis of gastrointestinal stromal tumors. Methods All recombinant plasmids were stably transfected into CHO cells by liposomes. Western blotting was used to detect the expression of PDGFRA protein. The cell growth curve was plotted by cell counting. Flow eytometry was used to detect the cell cycle and apoptosis of CHO cell, respectively. The stably transformed cells were inoculated subcutaneously into the back of nude mice and the mice were used to observe the tumorigenesis. Transient transfection of the mutant-type plasmids of PDGFRA gene and the wild-type plasmids of kit gene into the CHO cells was performed. Western blot was used to detect the expression of kit protein and its phosphorylated fonus. Results PDGFRA protein expressed in the negative control, experimental group and positive control, except the empty vector. The growth curve showed that it was accelerated in the experimental group and positive control. The ratios of cells in proliferative phase were 28.4% (blank), 24.5% (negative control), 43.8% (experimental group) and 40.9% (positive control). Their apoptotic indexes were 1.8%, 1.9%, 1.5% and 1.6%, respectively. After three weeks, tumors were observed in the nude mice of experimental group and positive control, inoculated with the stably transformed cells. Moreover, the expression of phosphorylated protein of kit was enhanced after cotrausfection of the mutant-type plasmicls of PDGFRA and the wild-type plasmid of kit. Conclusion The PDGFRA mutant L839P is a gain-of-function mutation and has obviously malignant transforming effect onnormal cells, and may activate kit protein accelerating the tumorigenesis.