Gastric Cancer
Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 15, 2003; 9(12): 2662-2665
Published online Dec 15, 2003. doi: 10.3748/wjg.v9.i12.2662
Somatic mutation analysis of p53 and ST7 tumor suppressor genes in gastric carcinoma by DHPLC
Chong Lu, Hui-Mian Xu, Qun Ren, Yang Ao, Zhen-Ning Wang, Xue Ao, Li Jiang, Yang Luo, Xue Zhang
Chong Lu, Hui-Mian Xu, Zhen-Ning Wang, Laboratory of Medical Genomics, Oncology Department, the First Affiliated Clinical College, China Medical University, Shenyang, 110001, Liaoning Province, China
Qun Ren, Yang Ao, Xue Ao, Li Jiang, Yang Luo, Laboratory of Medical Genomics, China Medical University, Shenyang, 110001, Liaoning Province, China
Xue Zhang, Laboratory of Medical Genomics, China Medical University, Shenyang, 110001, Liaoning Province, China. Laboratory of Genetics, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100021, China
Author contributions: All authors contributed equally to the work.
Supported by National Science Fund for Distinguished Young Scholars, No. 30125017, and the Major State Basic Research Development Program of China (973 Program), No. G1998051203
Correspondence to: Xue Zhang, Laboratory of Medical Genomics, China Medical University, No. 92, Bei Er Road, Heping District, Shenyang, 110001, Liaoning Province, China. xzhang@mail.cmu.edu.cn
Telephone: +86-24-23256666-5532
Received: April 4, 2003
Revised: May 12, 2003
Accepted: June 7, 2003
Published online: December 15, 2003
Abstract

AIM: To verify the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in detecting somatic mutation of p53 gene in gastric carcinoma tissues. The superiority of this method has been proved in the detection of germline mutations, but it was not very affirmative with respect to somatic mutations in tumor specimens. ST7 gene, a candidate tumor suppressor gene identified recently at human chromosome 7q31.1, was also detected because LOH at this site has also been widely reported in stomach cancer.

METHODS: DNA was extracted from 39 cases of surgical gastric carcinoma specimen and their correspondent normal mucosa. Seven fragments spanning the 11 exons were used to detect the mutation of p53 gene and the four exons reported to have mutations in ST7 gene were amplified by PCR and directly analyzed by DHPLC without mixing with wild-type allele.

RESULTS: In the analysis of p53 gene mutation, 9 aberrant DHPLC chromatographies were found in tumor tissues, while their normal-adjacent counterparts running in parallel showed a normal shape. Subsequent sequencing revealed nine sequence variations, 1 polymorphism and 8 mutations including 3 mutations not reported before. The mutation rate of p53 gene (21%) was consistent with that previously reported. Furthermore, no additional aberrant chromatography was found when wild-type DNA was added into the DNA of other 30 tumor samples that showed normal shapes previously. The positivity of p53 mutations was significantly higher in intestinal-type carcinomas (40%) than that in diffuse-type (8.33%) carcinomas of the stomach. No mutation of ST7 gene was found.

CONCLUSION: DHPLC is a very convenient method for the detection of somatic mutations in gastric carcinoma. The amount of wild type alleles supplied by the non-tumorous cells in gastric tumor specimens is enough to form heteroduplex with mutant alleles for DHPLC detection. ST7 gene may not be the target gene of inactivation at 7q31 site in gastric carcinoma.

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