Mahlavu cells, poorly differentiated and p53 mutants of a human hepatoma subline, are known to be highly refractory to a number of chemotherapeutic agents and radiotherapy due to their high expressions of multidrug resistance gene-1 (MDR-1) and Bcl-2 proteins. Thus, it is desirable to search for an alternative strategy for effective eradication of this type of cancer cells. We present evidence here for the first time that 6-shogaol (6-SG), an alkanone isolated from the rhizomes of ginger, can effectively induce apoptotic cell death of Mahlavu cells via an oxidative stress-mediated caspase-dependent mechanism. The cascade of events in 6-SG-induced apoptosis of these cells involved an initial overproduction of reactive oxygen species (ROS) followed by a severe depletion of intracellular glutathione (GSH) contents. Both events consequently entailed a significant drop in mitochondrial transmembrane potential (DeltaPsim), which ultimately activated the activities of caspases 3/7 resulting in the DNA fragmentation. Interestingly, we also found that N-acetylcysteine (NAC), an antioxidant and a precursor of GSH biosynthesis, could offer a near complete protection of apoptotic cell death exerted by 6-SG. Similarly, exogenously added GSH could also provide protection with an equal efficacy. However, it was paradoxical that both Boc-Asp(OMe)-fmk (a broad caspases inhibitor) and cyclosporin A (an mitochondrial permeability transition opening inhibitor) could only partially protect these cells from 6-SG-induced apoptosis. Taking these data into consideration, it is obvious that GSH depletion is the major contributing factor in arbitrating 6-SG-induced apoptosis of Mahlavu cells. In conclusion, we provide here a novel modality that can help to eradicate a p53 mutant of human hepatoma cells by using a natural consistent isolated form of ginger. These data also provide evidence to reaffirm the notion that consumption of certain foodstuffs can be beneficial to health because some of the constituents contained in them may be anticarcinogenic.

To elucidate physiological mechanisms underlying pathological anxiety, valid animal models are essential (Cryan and Holmes 2005). Previous studies confirmed that the high anxiety-related behavior/low anxiety-related behavior (HAB/ LAB) mouse model for trait anxiety mimics many clinically relevant features typical of psychiatric patients (Krömer et al. 2005;Landgraf et al. 2007). In this model, behavioral phenotyping on the elevated-plus-maze (EPM) test was used as selection criterion for bidirectional intra-strain (CD1) breeding. Consequently, inbreeding for more than 30 generations created hyper-anxious (HAB) and hypo-anxious (LAB) mice. These animals provide robust phenotypes for extremes in anxiety-related behavior, and show high comorbidity with depression-like behavior. Inbreeding with focus on a particular trait included a strong accumulation of specific genetic material. Therefore, HAB/LAB animals serve as a potent model to analyze candidates underlying trait anxiety. One of the first protein markers shown to be differentially regulated in extremes of trait anxiety was glyoxalase1 (GLO1; lactoylglutathione lyase, EC 4.4.1.5).Mouse GLO1 is an enzyme of 21kDa, containing 184 amino acids that is found as a dimer in the cytosol of cells. Its physiological function is the catalytic conversion of Abbreviations used: AGE, advanced glycation end; ARMS, amplification refractory mutation system; CNV, copy number variant; enpp5, ectonucleotide pyrophosphatase/phosphodiesterase 5; EPM, elevatedplus-maze; GC-MS, gas chromatography-mass spectrometry; GLO1, glyoxalase1; HAB, high anxiety-related behavior; i.c.v., intracerebroventricular; LAB, low anxiety-related behavior; LTP, long-term potentiation; MG, methylglyoxal; NAB, normal anxiety-related behavior; TST, tail suspension test; WB, western blotting. AbstractMethylglyoxal (MG) is a highly reactive metabolite that forms adducts with basic amino acid side chains in proteins. MG is degraded by glyoxalase1 (GLO1), an enzyme shown to be differentially expressed in several mouse models of anxietyrelated behavior. As yet, molecular mechanisms by which altered GLO1 expression influences emotionality have not been elucidated. Here we report that both MG concentration and protein modification are altered in brain tissue of a mouse model for trait anxiety, with elevated levels in low anxiety-related behavior relative to high anxiety-related behavior animals. Accordingly, repeated intracerebroventricular injections of MG mediated anxiolysis in inbred high anxiety-related behavior and outbred CD1 mice. We found that anxiolytic-like properties of MG were independent of GLO1 expression. In contrast, antidepressant-like properties of intracerebroventricular MG were suppressed in CD1 mice carrying extra copies of the GLO1 gene. Moreover, MG treatment increased expression of GLO1 only in CD1 mice that did not have extra copies of GLO1. Taken together, these results suggest that the MG levels in brain are negatively correlated with anxiety. Thereby, we identified a novel molecular mec...