Altered expression of tumor suppressors p16 and Rb in gastric carcinogenesis

Abstract

AIM: To determine whether expression of the tumor suppressors p16 and Rb is altered in gastric carcinoma.

METHODS: Mucosal biopsies were endoscopically obtained from patients with superficial gastritis (n = 12), atrophic gastritis (n = 15), atypical hyperplasia (n = 20) and gastric cancer (n = 40). Upon obtainment, all samples were immediately fixed with 10% buffered formalin, embedded in paraffin, and sectioned serially. Protein expression of p16 and Rb was detected by immunohistochemistry (ABC method).

RESULTS: The gastric epithelium samples showed various degrees of nuclear immunostaining for p16 and Rb according to the different stage of lesion. Progressive pathology of the lesions was associated with a decreasing trend in positive immunostaining for p16 protein (83.3% > 73.3% > 30.0% > 27.5%) but an increasing trend for Rb protein (25.0% > 46.7% > 60.0% > 67.5%). A negative correlation was found between these two parameters and gastric cancer. Correlation analysis of the 40 cases of gastric cancer identified a negative correlation for 20 of the cases. When positive (n = 9) and negative tissues (n = 11) were compared, a statistically significant difference was found (50.0%, 22.5%, 27.5%) (P < 0.05).

CONCLUSION: Abnormal expression of p16 and Rb may play an important role in gastric carcinogenesis.

Key Words: Genes, suppressor, tumor; Gene expression; Retinoblastoma protein/metabolism; Stomach neoplasms/metabolism; Carcinoma/metabolism