Evaluation of the immunohistochemical stain patterns of survivin, Bak and Bag-1 in colorectal cancers and comparison with polyps situated in the colon.

BACKGROUND/AIMS: Colorectal cancer is one of the most common cancers worldwide. The adenoma-carcinoma sequence in colorectal cancer has been documented approximately; however, several series of molecular mechanisms still require elucidation.

METHODOLOGY

Fifteen colonoscopic biopsy and 25 colectomy colorectal cancer samples, 12 hyperplastic colon polyps, and 18 tubular and 19 villous adenoma cases were studied. Apoptotic markers, such as Bag-1, survivin, and Bak, were used for staining, and relationships between stain features, clinical and prognostic factors, and polyp and tumor staining features were examined.

RESULTS

Significantly different staining patterns were observed between polyps and carcinomas. In tumor cells cytoplasmic Bag-1 expression was increased. As tumor differentiation degree tumor decreased, supranuclear granular staining features of Bcl-xl and Bak disappeared at a higher rate. With Bak, decrease of supranuclear granular staining was also related to vessel and nerve invasion, and tumor location. Survivin was expressed mostly in tumor cells, and sites with high inflammatory infiltration and vessel proliferation, where vessel endothelia were selectively stained.

CONCLUSIONS

Cytoplasmic staining of Bag-1 can be considered an indicator of tumor progression. Decrease of supranuclear granular staining with Bak and Bcl-xl, and survivin expression, can be used as indicators of poor prognosis. Survivin expression can also be used as a vessel marker.