DIFFERENCE IN EXPRESSION OF CD44 SPLICE VARIANTS BETWEEN PROXIMAL ANDDISTAL ADENOCARCINOMA OF THE LARGE-BOWEL

To help determine whether adenocarcinomas of the proximal and distal l arge bowel, reflect distinct entities, the expression of two splice va riants of the metastasis-associated cell adhesion molecule CD44, carry ing exons v5 and v6 respectively, was investigated retrospectively in fresh frozen samples of 23 proximal, and 41 distal carcinomas by immun ohistochemical staining with specific anti-CD44v5 monoclonal antibody VFF8 and anti-CD44v6 monoclonal antibodies VFF4 and VFF7. Tumours were staged as: Dukes A, 0; Dukes B, 27; Dukes C, 31; and Dukes 'D', six. Compared with distal tumours, proximal lesions expressed significantly more CD44v5 (96 versus 87 per cent, P = 0.02) and CD44v6 (83 versus 6 1 per cent P = 0.01), CD44v5 and CD44v6 are considered markers for tum our progression acid aggressive behaviour: Their high expression in pr oximal carcinomas seems to contrast with tile general belief that thes e tumours show less aggressive behaviour than left-sided lesions. Furt her study of the biological significance of the expression of CD44 spl ice variants is therefore needed.