Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 15, 2003; 9(3): 521-524
Published online Mar 15, 2003. doi: 10.3748/wjg.v9.i3.521
Overexpression of c-fos in Helicobacter pylori-induced gastric precancerosis of Mongolian gerbil
Yong-Li Yang, Bo Xu, Yu-Gang Song, Wan-Dai Zhang
Yong-Li Yang, Yu-Gang Song, Wan-Dai Zhang, Institute of Gastrointestinal Diseases, Nanfang Hospital, First Military Medical University, Guangzhou 510515, Guangdong Province, China
Bo Xu, Department of Orthopedics, Nanfang Hospital, First Military Medical University, Guangzhou 510515, Guangdong Province, China
Author contributions: All authors contributed equally to the work.
Correspondence to: Dr. Yong-Li Yao, Institute of Gastrointestinal Diseases, Nanfang Hospital, First Military Medical University, Guang-zhou 510515, Guangdong Province, China. xbyyl@fimmu.edu.cn
Telephone: +86-20-85141547 Fax: +86-20-87208770
Received: September 26, 2001
Revised: October 23, 2001
Accepted: November 6, 2001
Published online: March 15, 2003

AIM: To explore dysregulation of c-fos in several human malignancies, and to further investigate the role of c-fos in Helicobacter pylori (H. pylori)-induced gastric precancerosis.

METHODS: Four-week-old male Mongolian gerbils were employed in the study. 0.5 mL 1 × 108 cfu·L-1 suspension of H. pylori NCTC 11637 in Brucella broth were inoculated orally into 20 Mongolian gerbils. Another 20 gerbils were inoculated with Brucella broth as controls. 10 of the infected gerbils and 10 of the non-infected control gerbils were sacrificed at 25 and 45 weeks after infection. The stomach of each gerbil was removed and opened for macroscopic observation. The expression of c-fos was analyzed by RT-PCR and immunohistochemical studies in H. pylori-induced gastric precancerosis of Mongolian gerbil. Half of each gastric antrum mucosa was dissected for RNA isolation and RT-PCR. β-actin was used as the housekeeping gene and amplified with c-fos as contrast. PCR products of c-fos were analyzed by gel image system and the level of c-fos was reflected with the ratio of c-fos/β-actin. The immunostaining for c-fos was conducted using monoclonal antibody of c-fos and the StreptAvidin-Biotin-enzyme Complex kit.

RESULTS: H. pylori was constantly found in all infected animals in this study. After infection of H. Pylori for 25 weeks, ulcers were observed in the antral and the body of stomach of 60% infected animals (6/10). Histological examination showed that all animals developed severe inflammation, especially in the area close to ulcers, and multifocal lymphoid follicles appeared in the lamina propria and submucosa. After infection of H. Pylori for 45 weeks, severe atrophic gastritis in all infected animals, intestinal metaplasia in 80% infected animals (8/10) and dysplasia in 60% infected animals (6/10) could be observed. C-fos mRNA levels were significantly higher after infection of H. pylori for 25 weeks (1.84 ± 0.79), and for 45 weeks (1.59 ± 0.37) than those in control-animals (0.74 ± 0.22, P < 0.01). C-fos mRNA levels were increased 2.5-fold by 25th week (P < 0.01) and 2.1-fold by 45th week (P < 0.01) in precancerosis induced by H. pylori, when compared with normal gastric epithelium of Mongolian gerbil. Immunohistochemical staining revealed exclusive nuclear staining of c-fos. Furthermore, there was a sequential increase in c-fos positive cells from normal epithelium to precancerosis.

CONCLUSION: The study suggested that overexpression of c-fos occurs relatively early in gastric tumorigenesis in this precancerosis model induced by H. pylori.

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