Asymmetric Dimethylarginine in an NMU-induced Rat Mammary Tumor Model

Background/Aim: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) production and a newly discovered risk factor involved in endothelial dysfunction and adverse cardiovascular events. Recently, both NO and ADMA have also emerged as molecules of interest in carcinogenesis and tumor growth progression. Our earlier studies have confirmed elevated plasma ADMA levels in patients with hematological malignancies. However, the cause of elevated ADMA was unclear. The aim of this study was to assess the concentrations of ADMA, symmetric dimethylarginine (SDMA) and L-arginine in rats exposed to N-nitroso-N-methylurea (NMU) for the induction of mammary tumors. Materials and Methods: A total of 95 female rats of the Sprague-Dawley strain were used in the study. Plasma concentrations of ADMA, SDMA and L-arginine were quantified and statistically analyzed. Results: Mean ADMA levels were higher in the tumor-bearing group compared to the control group. Mean plasma levels of SDMA and L-Arginine were not significantly different between the groups. The L-ARG/ADMA ratio was lower in rats with tumors compared to controls. Conclusion: Histological assessment confirmed expression of ADMA within the tumor cells, which strongly suggests that these tumor cells were the source of ADMA. Other studies are warranted to further explain the role of ADMA in neoplastic diseases.