Association of malignancy of human colorectal carcinoma with IDO gene expression

Abstract

Objective To investigate the correlation of Indoleamine 2,3-dioxygenase (IDO) gene expression with malignancy of colorectal carcinoma. Methods The expression of IDO in 121 specimens of colorectal carcinoma, adjacent tissue, and normal mucus tissue was detected by using immunohistochemis-try with anti-IDO monoclone antibody, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. The correlation of the expression of IDO with various clinicopathologic characteristics of eolorectal carcinoma was analyzed statistically. Results 35.5% (43/121) of colorectal carcinomas ex-pressed IDO, and the expression of IDO was significantly upregulated in carcinoma as compared with adja-cent or normal mucus tissues. The positive rate of IDO in colorectal carcinoma with low-/un-differentiation, lymphnode or liver metastasis was up to 61.1%, 65.3% and 87.5% respectively, in which more than half was intensively stained (+++). Conclusion The upregulation of IDO gene expression in colorectal carcino-ma was correlated to tumor cell differentiation, clinic stage, and metastasis of the lymph node or liver. IDO may be an indicator of colorectal carcinoma prognosis. The high expression of IDO in the metastatic lymph node implies IDO might have a role in tumor immune escape by catalyzing tryptophan metabolism locally. Key words: Colorectal cancer; Gene expression; Indoleamine 2,3-dioxygenase