Expression of class III beta-tubulin in colorectal carcinomas: an immunohistochemical study using TU-20 & TuJ-1 antibody.

BACKGROUND & OBJECTIVE Expression of class III beta-tubulin represents newly discovered marker of resistance to taxol-based chemotherapy in a wide spectra of carcinomas. However, very little is known about its expression in colorectal carcinomas. This study was done to determine class III beta-tubulin expression in a large series of colonic carcinomas, covering tumours with different degree of differentiation in order to evaluate its prospective significance in resistance to taxol-based chemotherapeutics and to compare the immunostaining profile of two widely used monoclonal antibodies, TU-20 and TuJ-1 METHODS Sixty patients with colorectal carcinoma were enrolled; all of them were treated surgically by the resection. Twenty tumours were histologically assessed as G1, 20 as G2 and 20 as G3. Routine immunohistochemical procedure using TU-20 and TuJ-1 mouse monoclonal antibodies was applied to all 60 specimen and slides were evaluated using an optical microscope. RESULTS Expression of class III beta-tubulin was detected in 14 tumours (23.3%), while remaining tumours were negative. Relatively higher frequency of class III beta-tubulin expression was observed in G3 tumours (10 cases) in comparison with G1 (3 cases) and G2 (1 case), respectively. Seven tumours displayed positive immunostaining with both tested antibodies TU-20 and TuJ-1. Six tumours showed expression of class III beta- tubulin in more than 1 per cent of neoplastic cell population. In remaining 8 tumours only individual scattered neoplastic cells exhibited class III beta-tubulin expression either with TU-20, or with TuJ-1 antibody. INTERPRETATION & CONCLUSION Higher frequency of immunoreactivity was observed in poorly differentiated tumours. However, more than 90 per cent of neoplastic cell population did not express class III beta-tubulin in almost all tumours. These negative cells of colonic cancer could represent the potential target for taxane-based chemotherapy in the future. Our results indicate that TU-20 and TuJ-1 antibodies exhibit very similar immunoreactivity in neoplastic tissue.