Differential expression of mucins and trefoil peptides in native epithelium, Barrett's metaplasia and squamous cell carcinoma of the oesophagus.

In humans, trefoil peptides (TFF peptides) and some mucins have been reported to be expressed in a cell-specific manner at mucosal surfaces of normal gastrointestinal tissues. Neoplastic conditions cause characteristic changes of these expression patterns. To study such patterns in Barrett's metaplasia and squamous cell carcinoma of the oesophagus (SCC), the distribution of MUC1, MUC2, MUC5AC and the three TFF peptides (TFF1, TFF2 and TFF3) was investigated. In 40 archival samples of SCC and in 21 samples of Barret's metaplasia, expression of the three mucins and two TFF peptides (TFF1 and TFF2) was assessed by specific antibodies. Reverse transcriptase/polymerase chain reaction amplification (RT-PCR) was performed on frozen tissue samples from the 11 biopsies of SCC for the three TFF peptides. Immunohistochemical tests for MUC2 and TFF2 were negative both in samples of Barret's metaplasia and in SCC. MUC1 expression was detected in 57.5% of the tumour samples, while TFF1 and MUC5AC were found in 10% and 7.5% of the cases respectively. In Barrett's metaplasia MUC1 was detected in 90.5% of the cases and TFF1 and MUC5AC in all of them. RT-PCR analysis revealed a more complex pattern: TFF1 and TFF3 expressed the corresponding mRNA in all samples investigated; the third member, TFF2, was active in 45.5% of the carcinoma biopsies and not in the corresponding native tissue. This finding in oesophageal carcinoma contrasts with the situation found in normal and neoplastic stomach epithelium where TFF1 and TFF2 are found co-expressed and TFF3 remains silent. Interestingly, MUC1 is expressed in a significant proportion of SCC. Both in Barett's metaplasia and in SCC the expression of MUC5AC mirrors the TFF1 synthesis in intensity and spatial distribution.