Obesity is a risk factor for prostate cancer, and plasma levels of the adipokine, adiponectin, are low in the former but high in the latter. Adiponectin has been shown to modulate cell proliferation and apoptosis, suggesting that adiponectin and its receptors (Adipo-R1, Adipo-R2) may provide a molecular association between obesity and prostate carcinogenesis. We show for the first time, the protein distribution of Adipo-R1 and Adipo-R2 in LNCaP and PC3 cells, and in human prostate tissue. Using real-time RTPCR we provide novel data demonstrating the differential regulation of Adipo-R1 and Adipo-R2 mRNA expression by testosterone, 5-alpha dihydrotestosterone, beta-estradiol, tumour necrosis factor-alpha, leptin, and adiponectin in LNCaP and PC3 cells. Our findings suggest that adiponectin and its receptors may contribute to the molecular association between obesity and prostate cancer through a complex interaction with other hormones and cytokines that also play important roles in the pathophysiology of obesity and prostate cancer. (c) 2006 Elsevier Inc. All rights reserved.