Patterns of expression of trefoil peptides and mucins in gastric polyps with and without malignant trans formation

The expression of two trefoil peptides (TFF1 and TFF2) and four mucins (MUC 1, MUC2, MUC5AC, and MUC6) was evaluated by inmunohistochemistry and revers e transcription-polymerase chain reaction (RT-PCR) in 29 gastric polyps, 10 hyperplastic and 19 adenomatous, eight of which displayed malignant transf ormation, The aims of this study were to characterize the expression profil e of these molecules in each type of polyp and to investigate possible modi fications of the profile during the process of malignant transformation, Al l hyperplastic polyps displayed immunoreactivity for TFF1, MUC5AC, and MUC1 in more than 75 per cent of the cells. In adenomatous polyps, three main p henotypes could be identified: complete gastric phenotype (co-expression of TFF1 and MUC5AC)-nine cases (47.4 per cent); incomplete gastric phenotype (TFF1-positive and MUC5AC-negative)-seven cases (36.8 per cent); non-gastri c (intestinal) phenotype (no expression of TFF1 or MUC5AC)-three cases (15. 8 per cent), Data yielded by immunohistochemistry and RT-PCR showed a good correlation for both TFF1 and TFF2, One hyperplastic and seven adenomatous polyps with villous architecture displayed foci of diffuse and intestinal-t ype carcinoma, respectively; in all of these cases, MUC1 expression and sig ns of gastric differentiation were observed in both the non-malignant and t he carcinomatous component, It is concluded that gastric differentiation is a feature of hyperplastic polyps and of a subset of adenomatous polyps whi ch is shared by early carcinomas arising in some of these polyps, regardles s of the histological type of polyp and of carcinoma. Copyright (C) 1999 Jo hn Wiley & Sons, Ltd.