Molecular Oncological Analysis of Human Kidney Tumors

用NIH/3 T3转染法检测了16例原发性肾肿瘤、15例肾细胞癌和1例移行细胞癌中的两种H-ras癌基因。ras M_r 21，000蛋白的分析表明在每一个病例中密码子12和61处发生单点突变。其中1例H-ras基因第12位密码子的限制性内切酶分析证实了这一点，其余15例肿瘤在该位点没有突变。来自具有密码子12突变的肿瘤的肾脏的非癌部分的DNA，而不是来自同一患者的白细胞，显示出对内切核酸酶MspI和HpaII的异常抗性，表明密码子12突变的H-ras基因存在于非癌细胞中。在16个肿瘤中没有检测到ras基因扩增。在H-ras相关BamHI限制性片段杂合子患者的8个肿瘤中，1个等位基因在肿瘤中丢失，但在同一肾脏的非癌部分中未丢失。细胞遗传学研究提示c-raf-1基因在肾细胞癌中的表达是非随机的，但在15例肾细胞癌中均未发现c-raf-1基因转录本大小和数量的异常。我们的研究结果表明，影响ras基因的遗传病变确实发生在人类肾癌，并可能作为致癌过程中的多个步骤之一。

Two H-ras oncogenes were detected bY NIH/3T3 transfection assay out of 16 primary kidney tumors, 15 renal cell carcinomas (RCC), and one transitional cell carcinoma in 16 patients. Analysis of ras M_r 21,000 protein suggested single point mutations within codon 12 and 61 in each case. The restriction endonuclease analysis of H-ras gene at codon 12 confirmed this in one of them, and the remaining 15 tumors did not have a mutation at this site. DNAs from the noncancerous portions of the kidney with codon 12 mutated tumor, but not leukocytes from the same patient, showed an abnormal resistance to the endonucleases MspI and HpaII, suggesting a presence of codon 12 mutated H-ras gene in the noncancerous cells. No amplification of ras genes was detected in the 16 tumors analyzed. In one of eight tumors from patients heterozygous for H-ras related BamHI restriction fragments, one allele was lost in the tumor but not in the noncancerous portion of the same kidney. Although cytogenetic studies have previously suggested nonrandom involvement of c-raf-1 gene in RCC, no abnormality in the size nor amount of raf transcript was detected in the 15 RCCs. Our results thus indicated that the genetic lesions affecting ras genes do occur in human RCC, and probably serve as one of multisteps in the carcinogenic process.