Mucin gene transcripts in benign and borderline mucinous tumours of the ovary: an in situ hybridization study

Mucinous tumours of the ovary are characterized by mucin-secreting cells ex hibiting a variable endocervical, intestinal, gastric or pancreatobiliary p henotype as ascertained by microscopy, electron microscopy, histochemistry or immunohistochemistry. The molecular mechanisms underlying the tumourigen esis process are not well understood, The mucin glycoproteins expressed by ovarian mucinous tumours have not been fully characterized, but mucins are known to be implicated in tumour progression in various epithelial neoplasm s. The purpose of this study was to evaluate the expression of mucin genes (MMC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6) in ovarian mucinous tumour ce lls, to relate MUC gene expression to the histological diagnosis, and to co mpare the expression patterns with those observed in normal tissues. The ex pression of mucin genes was evaluated by in situ hybridization in 21 mucino us tumours (11 adenomas and ten borderline tumours), Heterogeneity of expre ssion correlated with morphological heterogeneity. Intense expression of th e MUC5AC gene, suggesting a gastric surface cell phenotype, was demonstrate d in 18/21 tumours (86%). Goblet cells expressing the MUC2 gene and columna r cells expressing the MUC3 gene were consistent with an intestinal phenoty pe, which was observed in 15 tumours (71%) including nine adenomas and sis borderline tumours, Major expression of MUC4 and MUC5B consistent with an e ndocervical phenotype mas observed in seven benign (64%) and three borderli ne (30%) tumours, In all, the MUC profiles suggested gastrointestinal-type cells in 13 cases (62%), gastric-type cells in five cases (24%), and intest inal-type cells in two cases (one benign, one borderline) (9%); the results mere inconclusive in one borderline tumour (5%), It is concluded that gast ric and, to a lesser degree, intestinal and almost constant events in ovari an mucinous tumourigenesis. borderline tumour (5%), differentiation are ear ly and almost cons Copyright (C) 2000 John Wiley & Sons, Ltd.