l-asparaginase induces intrinsic mitochondrial-mediated apoptosis in human gastric adenocarcinoma cells and impedes tumor progression

L-asparagine essentially regulates growth and proliferation of cancer cells. L-asparaginase is an anticancer enzyme that deprives the cancer cells of L-asparagine. The purpose of this study was to explore the mechanism of a novel L-asparaginase from Pseudomonas fluorescens on L-asparagine deprivation mediated anti-proliferation, apoptosis in human gastric adenocarcinoma cells and to evaluate inhibition of angiogenesis. We observed that, the presence of extracellular L-asparagine was essential for the growth of AGS cells. L-asparagine deprivation by L-asparaginase induced metabolic stress, cytotoxicity and apoptosis by G0 phase cell-cycle arrest, modulated the mitochondrial membrane integrity, accelerated caspase-3 activation and instigated DNA damage. The RT-PCR analysis of pro-apoptosis genes: bak1, bax, bbc3, bik, pmaip1, bnip3l, apaf1, casp3, casp7 and casp9 were significantly higher (P < 0.05), while anti-apoptotic markers xiap, bid, mcl1, and death receptor genes tnf and tradd were significantly down-regulated (P < 0.05). Additionally, higher protein expressions of p53, caspase-3 and TEM analysis showing modulations in mitochondria confirmed intrinsic apoptosis pathway. The enzyme impeded tumor progression through inhibition of cell migration and vascular remodelling of endothelial cells. Our findings suggests that the action of L-asparaginase alters mitochondrial membrane permeability and auxiliary activates intrinsic apoptosis. Therefore, this mechanistic approach might be considered as a targeted enzymotherapy against gastric adenocarcinoma.