Expression of adiponectin receptors, AdipoR1 and AdipoR2, in normal colon epithelium and colon cancer tissue

Adiponectin is secreted by adipocytes and is a key hormone responsible for insulin sensitization. Recent studies have shown that plasma adiponectin is decreased in patients with breast, endometrial and gastric cancer. However, the effect of adiponectin on colorectal carcinogenesis is controversial. It is now well known that the adiponectin receptor exists in two isoforms, adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2). We examined the expression of the adiponectin receptors on normal colon mucosa and colon cancer tissues in a human study using real-time RT-PCR, Western blotting and immunohistochemical staining. Adiponectin receptors, AdipoR1/AdipoR2, were expressed in normal colon epithelial and colon cancer cells. Furthermore, laser microdissection was performed to confirm our results. These results suggest that adiponectin may exert some effects on normal colon epithelium or colon cancer cells directly through adiponectin receptors. Further studies are required to elucidate the function of the AdipoRs activated by adiponectin and the downstream mechanisms of AdipoRs in colon cancer cells.