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目的 :探讨人食管癌DNA聚合酶beta (polβ)基因突变的特点。 方法 :对 75例人食管癌组织及 4例正常对照组织中提取总RNA ,进行RT PCR ,对PCR产物克隆后以Sanger’s法测序。结果 :人食管癌标本的polβ基因突变率 36 % (2 7/ 75 )。突变形式包括 :①A :G转换 ,突变频率为 6 6 .7% (18/ 2 7) ,375位的A→G (Ile→Val)、4 6 6位G→A(Gly→Glu)、6 6 0位A→G (Arg→Gly)、6 70位A→G(Glu→Gly)、74 0位A→G (Lys未改变 ) ;②T :C转换 ,突变频率 18.5 % (5 / 2 7) ,4 5 4位T→C(Phe→Ser)、6 6 5位T→C (Gly未改变 ) ;③G :T颠换 ,突变频率 18.5 % (5 / 2 7) ,4 6 2位G→T (Glu→提前终止于 116aa) ;④A :T颠换 ,突变频率 18.5 % (5 / 2 7) ,6 13位A→T(Lys→Ile)、737位A→T(Pro未改变 ) ;⑤G :C颠换 ,突变频率 7.4 % (2 / 2 7) ,6 4 8位G→C(Gly→Arg) ;⑥ 177～ 2 34位的 5 8bp缺失 ,移码及提前终止 ,突变频率为 37% (10 / 2 7)。结论 :人食管癌组织 polβ基因突变具有以下特点 :①标本突变率达 36 %(2 7/ 75 ) ;②有以A :G转换和G :T颠换为热点等多种突变形式 ;③ 2种提前终止可产生 2种截短的polβ蛋白 ,1种具有 116氨基酸长度 ;另一种 5 8bp的缺失者仅有 2 6氨基酸长度
Objective: To investigate the characteristics of DNA polymerase beta (polβ) gene mutation in human esophageal cancer. Methods: Total RNA was extracted from 75 human esophageal cancer tissues and 4 normal control tissues. The PCR products were cloned and sequenced by Sanger’s method. Results: The mutation rate of polβ gene in human esophageal cancer specimens was 36% (27/75). The mutation forms include: ① A: G mutation, the mutation frequency was 6.67% (18/27), A → G (Ile → Val) at 375, G → A (Gly → Glu) at 466, 6 0 A → G (Arg → Gly), 6 70 A → G (Glu → Gly), 74 0 A → G (Lys unchanged); ②T: C conversion, mutation frequency 18.5% ), 454 T → C (Phe → Ser), 6 6 5 T → C (Gly unchanged); ③ G: T transversion, the mutation frequency of 18.5% (5/27) → T (Glu → premature termination at 116 aa); ④ A: T transversion with a mutation frequency of 18.5% (5/27), 6 13 A → T (Lys → Ile), 737 A → T ; ⑤ G: C transversion, mutation frequency of 7.4% (2/2 7), 6 4 8 G → C (Gly → Arg); ⑥ 177 bp to 234 bits of 5 8bp deletion, frameshift and premature termination, mutation frequency Was 37% (10/27). Conclusion: The mutation of polβ gene in human esophageal carcinoma has the following characteristics: ① The mutation rate of the specimen is 36% (2 7/75); ② There are many kinds of mutations such as A: G conversion and G: T transversion as hot spots; ③ 2 Two species of truncated polβ protein, one with a length of 116 amino acids, and the other with a length of 56 amino acids