青石棉与苯并（a）芘联合诱发大鼠肺癌Ki－ras癌基因点突变

用青石棉＋苯并（ａ）芘碘油混悬液对大鼠气管注入染尘，取染尘后１８０和２７０天剖检的肺组织标本２５例。提取标本中ＤＮＡ，用人工合成的寡核苷酸引物进行ＰＣＲ体外扩增，再用γ－３２ＰＡＴＰ标记正常和两种突变Ｋｉ－ｒａｓ１２位探针，杂交，放射自显影。结果表明，正常对照组７例标本Ｋｉ－ｒａｓ１２位点突变为阴性，青石棉＋苯并（ａ）芘组１８例标本中，３例Ｋｉ－ｒａｓ１２位点突变为阳性，其中２例由ＧＧＴ（Ｇｌｙ）突变为ＡＧＴ（Ｓｅｒ），１例由ＧＧＴ（Ｇｌｙ）突变为ＴＧＴ（Ｃｙｓ），并对突变原因进行了探讨。

STUDIES OF Ki-RAS ONC0GENE MUTATION TESTS IN RAT LUNG CANCER INDUCED BY CROCIDOLITE PLUS BENZO (a)PYRENE

sample was prepared in iodized oil by mixing crocidolite(Cro.)to 20 mg per ml plus benzo(a)pyrene(B(a)P) to 50 mg perml.0.1 ml sample was injected intratracheally into each rat, once a month for 3 months. 25 lung tissue samples(7 normal control,18 Cro. plus B(a)P were obtained on the l80th and 270th day after the last injection. Ki-ras specific sequence of sample DNA wasamplified in vitro by PCR. The normal and two kind of mutation Ki-ras l2 codon probes were hybridized with salnple DNA. The re-sults showed:1)Ki-ras l2 codon mutation tests of 7 samples in normal control were negative;2)3 among the l8 samples in Cro. plus B(a)P group were positive in Ki-ras l2 codon mutation test. In regard to the pathological appearance of these 3 positive sam-ples,one was squamous cell carcinoma,the other two precancerosis or epitheliosis.