Evaluation of antitumor effects of two vine stalk oligomers of resveratrol on a panel of lymphoid and myeloid cell lines: comparison with resveratrol.

This study aims to evaluate and compare the antiproliferative and proapoptotic effects of resveratrol (trans-3,4',5-trihydoxystilbene) with two of its naturally occurring oligomers, epsilon-viniferin (a dimer) and miyabenol C (a trimer). Proliferation assays performed on myeloid and lymphoid cell lines show that the three compounds inhibit cell growth of all cell types tested, with miyabenol C being the most efficient (IC50 ranging from 10.8 to 29.4 muM). Further analysis performed on the multiple myeloma cell line U266 shows that all compounds modify cell cycle distribution probably via actions on different targets. Whereas cells treated with resveratrol accumulate in S phase, cells treated with epsilon-viniferin and miyabenol C accumulate in G2/M and G0/G1, respectively. Miyabenol C is also the most efficient at inducing cell death in U266 cells. All compounds induce apoptosis of U266 cells via mechanisms entirely dependent on caspase activation and associated with mitochondrial membrane potential disruption. Compounds do not act directly on the mitochondrial membrane, but could induce activation of upstream caspases such as caspase 8 and/or caspase 2, depending on the compound. In no case did upstream caspase 8 activation involve Fas/FasL interaction. Taken together, these results show that epsilon-viniferin and, more importantly, miyabenol C represent potent antitumor agents that require further investigation, either alone or in combination with resveratrol.