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.
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.
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.
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).
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.