Abstract A137: NO initiates progression of human melanoma via a feedback loop mediated by APE/Ref-1, new opportunities for chemoprevention.

A137 It is well recognized that nitric oxide (NO) is involved in tumor progression, including melanoma. Measurement of proliferative and metastatic capacity by MTS and Matrigel-invasion assays respectively were done. NO-treated melanoma cells(especially metastatic Lu1205) exhibited a higher capacity compared with control, especially metastatic Lu 1205 cells. Apurinic/apyrimidinic endonuclease-1/redox effector factor-1 (APE/Ref-1) is a multifunctional protein, and its role in tumor biology has attracted considerable attention. To determine whether APE/Ref-1 plays a role in mediating NO-stimulation of melanoma progression, we investigated the effect of DETA/NO on levels of APE/Ref-1 and related downstream targets (Activator Protein-1 (AP-1)/Jun D, Matrix Metalloproteinase-1 (MMP-1), Bcl-2, and inducible nitric oxide synthase (iNOS)) by Western Blot and RT-PCR analysis. Following DETA/NO treatment, APE/Ref-1 and other downstream molecules were induced. Knockdown of APE/Ref-1 or AP-1/Jun D by specific siRNA markedly reversed the induction by NO stress of target proteins. These results present evidence for the existence of a functional feedback loop contributing to progression and metastatic capacity of melanoma cells. Resveratrol has been demonstrated to be an APE/Ref-1 inhibitor, and significant decreases in AP-1/JunD, MMP-1, Bcl-2, and iNOS protein levels occurred after exposure to resveratrol. This phenolic antioxidant as well as other inhibitors of Ref-1 may be an appropriate choice for combining with other compounds against melanoma cells that develop resistance by up-regulations of these molecules. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A137.