Adiponectin immunohistochemical expression in colorectal cancer and its correlation with histological grade and tumour microvessel density

Aims: Adiponectin (ApN) is a 30 kDa adipo-cytokine with anti-angiogenic effects. The expression of its receptors, Adipo-R1 and Adipo-R2, has been reported in colorectal cancer tissue and cell lines, but ApN expression in this neoplasia has not been investigated until now. In the present study, we aimed to analyse ApN expression and its eventual correlations with the clinico-pathological parameters and with the quantity of neo-angiogenesis, as reflected by the microvessel density (MVD), in human sporadic surgically resected colorectal carcinomas. Methods: A total of 45 formalin-fixed, paraffin-embedded colorectal carcinomas were submitted to the immunohistochemical procedures for ApN and CD105, a specific marker for neo-angiogenesis which was used in the assessment of MVD. Results: ApN expression was evidenced in 12 of 45 colorectal carcinomas, and it was significantly associated with a high histological grade (p = 0.0002) and a low MVD count (p = 0.0471) of the tumours. No ApN immuno-expression was found in the epithelial cells lining the adjacent normal colorectal mucosa. Conclusions: Our findings suggest an anti-angiogenic role for ApN in colorectal cancer. Nonetheless the significance of the prevalent expression of this cytokine in high-grade colorectal carcinomas needs to be elucidated before considering the use of ApN analogues as novel possible antitumour agents.