Motexafin Gadolinium and Zinc Induce Oxidative Stress Responses and Apoptosis in B-Cell Lymphoma Lines. Homo sapiens

We report the effect of motexafin gadolinium (MGd) and exogenous zinc on intracellular levels of free zinc, oxidative stress, proliferation, cell cycle, and cell death in exponential phase human B-cell lymphoma and other hematologic cell lines. We find that increased levels of oxidative stress and intracellular free zinc precede and correlate with cell cycle arrest and apoptotic response. Treatment with exogenous zinc increased oxidative stress and, conversely, oxidative stress resulted in increased intracellular free zinc levels. To better understand the molecular basis of these results, gene expression profiling analyses were conducted on Ramos cell cultures treated with MGd and/or zinc acetate. Cultures treated with MGd or zinc acetate alone elicited transcriptional responses characterized by induction of MTF-1 and HIF-1 regulated genes. Cultures co-treated with MGd and zinc acetate displayed further increases in the levels of MTF-1 and HIF-1 regulated transcripts as well as additional transcripts regulated by NRF-2. Overall, these studies suggest that co-treatment of Ramos cells with MGd and zinc acetate increase intracellular zinc levels with a concomitant rise in oxidative stress levels that activate adaptive survival responses but eventually lead to cell death. Keywords: Dose response Overall design: Ramos cells were treated with MGd alone or along with different concentrations of zinc acetate. Each treatment was done in triplicates. Expression was compared to that of cells treated with mannitol.