Expression of retinoblastoma and cyclin D1 in gastric carcinoma.

Abnormal regulation of the cell cycle is a feature of many neoplasms. The role of cell cycle regulators in oncogenesis has been investigated in many human tumors. Alteration of the retinoblastoma (pRb) and cyclin D1 disrupt the Rb pathway and occur in many carcinomas. However the expression of the Rb and cyclin D1 in intestinal type gastric carcinoma is unclear. The purpose of this study was to investigate the expression of Rb and cyclinD1 in resected gastric carcinoma, their adjacent nonneoplastic mucosa and normal gastric mucosa, and finally to provide insights into the role of the Rb and cyclin D1 in gastric carcinogenesis. We investigated Rb and cyclin D1 expression in 43 patients (32 men, 11 women; mean age: 64) with primary gastric adenocarcinoma and compared the results with adjacent nonneoplastic mucosa. Adjacent nonneoplastic mucosa consisted of atrophy, dysplasia, intestinal metaplasia and gastritis. Expression of Rb was detected in 30 (69.7%) of gastric carcinoma, 18 (41.8%) of the adjacent nonneoplastic mucosa. Expression of cyclinD1 protein was detected in 31 (72%) of gastric carcinoma, 24 (55.8%) of adjacent nonneoplastic mucosa. Expression of Rb and cyclinD1 was not detected in normal gastric mucosa. The positive rate of Rb and cyclin D1 expression in gastric carcinoma was significantly higher than that adjacent nonneoplastic mucosa (p<0.05). There were significant trends for increased expression of Rb and cyclinD1 from nonneoplastic mucosa including atrophy, dyplasia, intestinal metaplasia and gastritis to carcinoma. These results suggested that positive expression of pRb and cyclinD1 might be an early event in gastric carcinoma and it tend to begin at precursor lesions and maintain throughout the progression of infiltration. Key words: Retinoblastoma, cyclin D1, gastric carcinoma, dysplasia, atrophy, intestinal metaplasia.