Effect of Helicobacter pylori eradication on expression of cyclin D2 and p27 in gastric intestinal metaplasia

Background and aims: Cyclins and cyclin-dependent kinase inhibitors play a crucial role in the control of cell cycle transitions. Enhanced expression of cyclin D2 and reduced expression of p27(kip1) (p27) have been implicated in the pathogenesis of cancer. Because intestinal metaplasia has been rega rded as a premalignant lesion, we investigated the expression of cyclin D2 and p27 in Helicobacter pylori-associated chronic gastritis with and withou t intestinal metaplasia, and followed the changes after H. pylori eradicati on, Methods: Expression of cyclin D2 and p27 was studied by immunohistochemistr y in 59 patients (including 35 patients with intestinal metaplasia) and in 10 gastric cancer patients. Among them, 29 H. pylori-infected patients had serial gastric biopsies taken before and at 1-year after eradication of H. pylori. Results: Expression of cyclin D2 was significantly higher in gastric cancer s when compared to their adjacent non-tumour tissues (median score 3 vs. 1, P = 0.015). Over-expression of cyclin D2 was detected in H. pylori-associa ted chronic gastritis and intestinal metaplasia, which was reduced after er adication of the organism (median score 2 vs. 1, P = 0.037 in chronic gastr itis; median score 2 vs. 0, P = 0.008 in intestinal metaplasia). While the normal gastric mucosa showed strong p27 expression, five of the 10 gastric cancer tissues exhibited reduced p27 expression (P = 0.039). Diminished p27 expression was also seen in intestinal metaplasia, which was restored 1-ye ar after H. pylori eradication (eight out of 16 vs. one out of 16, P = 0.01 8). Reduced expression of p27 was frequently associated with increased cycl in D2 expression in H. pylori-associated intestinal metaplasia (P = 0.02). Conclusion: Over-expression of cyclin D2 and reduced expression of p27 are closely linked to H. pylori-associated intestinal metaplasia. Eradication o f H. pylori infection reverses the aberrant expression of cyclin D2 and p27 in intestinal metaplasia.