Expression of orotate phosphoribosyltransferase in colorectal carcinoma: an immunohistochemical analysis in several components of neoplastic lesions.

The purpose of this study was to evaluate the pattern of the expression of orotate phosphoribosyltransferase (OPRT) in several components of colorectal carcinoma (CRC). Fifty-six surgically-resected samples of CRC were subjected to immunohistochemistry with a polyclonal anti-OPRT antibody. Grading was performed independently for several components of CRC, including mucosal carcinoma lesions (n=56), infiltrative lesions (n=53), lymphovascularly invasive lesions (n=34) and metastatic lymph nodes (n=17). The expression of OPRT in mucosal carcinoma and infiltrative lesions correlated significantly only with the presence of lymphovascular invasion (p=0.0007 and <0.0001, respectively). The frequency of OPRT expression in mucosal carcinoma, infiltrative and lymphovascularly invasive lesions as well as metastatic lymph nodes was 32.1, 69.8, 88.2 and 88.8%, respectively. In addition, nuclear staining of OPRT was observed in metastatic lymph nodes and lymphovascularly invasive lesions. Our results suggest that OPRT is involved in the invasion and metastasis of CRC.