Oxalomalate reduces tumor progression in melanoma via ROS-dependent proapoptotic and antiangiogenic effects

ROS-ATM-CHK2 axis stabilizes HIF-1α and promotes tumor angiogenesis in hypoxic microenvironment

Hypoxia is an established hallmark of tumorigenesis. HIF-1α activation may be the prime driver of adaptive regulation of tumor cells reacting to hypoxic conditions of the tumor microenvironment. Here, we report a novel regulatory mechanism in charge of the fundamental stability of HIF-1α in solid tumor. Under hypoxic conditions, the checkpoint kinase CHK2 binds to HIF-1α and inhibits its ubiquitination, which is highly likely due to phosphorylation of a threonine residue (Thr645), a formerly uncharacterized site within the inhibitory domain. Meanwhile, HIF-1α phosphorylation induced by CHK2 promotes complex formation between HIF-1-α and the deubiquitination enzyme USP7, increasing stability under hypoxic conditions. This novel modification of the crosstalk between phosphorylation and ubiquitination of HIF-1α mediated by CHK2 enriches the post-translational modification spectrum of HIF-1α, thus offering novel insights into potential anti-angiogenesis therapies.

Effect of Chitosan oligosaccharides on ischemic symptom and gut microbiota disbalance in mice with hindlimb ischemia

This study was designed to explore the effect of Chitosan oligosaccharides (COS) on mouse hindlimb ischemia by femoral artery ligation. Here, we demonstrated that COS treatment statistically promoted the blood perfusion and neovascularization in ischemic hindlimb of mice, accompanied by the suppression of inflammation and oxidative stress. By 16S rDNA gene sequencing, the disbalanced gut microbiota was observed in ischemic mice, while COS treatment, at least in part, restored the abundance changes of some intestinal bacteria at either phylum or genus levels. Based on metabolomics analysis on mouse plasma by UPLC-QTOF-MS, we screened 20 metabolites with the largest responses to ischemia, several of which were markedly reversed by COS. By Spearman's correlation analysis, the changed metabolites might act as a bridge between improved intestinal bacterial structure and alleviated hindlimb ischemia of mice treated by COS. Our studies point towards a potential role of COS in treatment of peripheral ischemia diseases.

Oxalomalate regulates the apoptosis and insulin secretory capacity in streptozotocin-induced pancreatic β-cells

Diabetes mellitus (DM) is a kind of metabolic disorder characterized by long-term hyperglycemia. Oxidative stress is involved in inducing the apoptosis of pancreatic β-cells and promoting the development of DM. Oxalomalate (OMA) is a competitive inhibitor of two classes of NADP+-dependent isocitrate dehydrogenase isoenzymes that are the main nicotinamide adenine dinucleotide phosphate (NADPH) producers to scavenge cellular reactive oxygen species (ROS). However, the role of OMA in DM remains unclear. The present study aimed to investigate the protective effects of OMA on streptozotocin (STZ)-induced β-cell damage and its underlying mechanisms. The viability of rat insulinoma cell line (INS-1) and the contents of ROS, nitric oxide and NAPDH were examined after cells being treated with STZ. After treatment with OMA in STZ-stimulated INS-1, the cell viability, apoptosis, and apoptosis-related proteins were measured. Meanwhile, the levels of oxidative stress-related factors and the changes of insulin secretion were determined. The results revealed that OMA significantly increased the cell viability (p < .05), reduced the apoptotic rate (p < .001), and altered the expression levels of Bcl-2, Bax, cleaved caspase3, and cleaved-caspase9 (p < .05 or p < .01) in STZ-induced INS-1 cells. Moreover, OMA enhanced the activities of superoxide dismutase, catalase, glutathione peroxidase (p < .01), whereas reduced the levels of ROS, malondialdehyde and lactic dehydrogenase (p < .001). Furthermore, OMA improved the ability of insulin secretion. These results indicated that OMA might have antioxidative stress and anti-apoptosis effects to protect INS-1 cells from STZ-induced cell damage.