Correlative study of microvessel density and 5-lipoxygenase expression in human sporadic colorectal cancer

CONTEXT: 5-Lipoxygenase (5-LO) is an arachidonic acid- metabolizing enzyme, which has been demonstrated to exert a role in colorectal cancer tumorigenesis. Its activity in promoting neoangiogenesis in colorectal malignancies has been also recently theorized on the basis of in vitro studies. OBJECTIVE: To investigate whether any correlation existed between 5-LO immunoexpression amount and the quantity of neoangiogenesis, as reflected by microvessel density (MVD) in human sporadic surgically resected colorectal adenocarcinomas. DESIGN: A total of 45 formalin-fixed, paraffin-embedded colorectal adenocarcinomas were submitted to the immunohistochemical procedures for 5-LO and CD105, which represent specific markers for neoangiogenesis and which were used in the assessment of MVD. RESULTS: CD105-positive, intratumoral, newly formed vessels were present in 45 of 45 cases with variable MVD values. A 5-LO-positive immunohistochemical reaction was also found in 45 of 45 cases. A significantly higher MVD was evident in cases displaying a high 5-LO amount in comparison with those characterized by a low 5-LO expression (28.33 vs 19.44 vessels per mm(2); P = .02). In addition, a positive significant correlation emerged between 5-LO immunoexpression amount and the MVD counts (r = 0.2986, P = .04). CONCLUSIONS: Our study demonstrates the existence of a relationship between 5-LO expression and the neoangiogenesis process as reflected by intratumoral MVD in human sporadic colorectal adenocarcinomas, thus suggesting that 5-LO may modulate the formation of blood vessels in these neoplasias.