A high-throughput screening campaign against PFKFB3 identified potential inhibitors with novel scaffolds.

The growth of solid tumors depends on tumor vascularization and the endothelial cells (ECs) that line the lumen of blood vessels. ECs generate a large fraction of ATP through glycolysis, and elevation of their glycolytic activity is associated with angiogenic behavior in solid tumors. 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) positively regulates glycolysis via fructose-2/6-bisphosphate, the product of its kinase activity. Partial inhibition of glycolysis in tumor ECs by targeting PFKFB3 normalizes the otherwise abnormal tumor vessels, thereby reducing metastasis and improving the outcome of chemotherapy. Although a limited number of tool compounds exist, orally available PFKFB3 inhibitors are unavailable. In this study we conducted a high-throughput screening campaign against the kinase activity of PFKFB3, involving 250,240 chemical compounds. A total of 507 initial hits showing >50% inhibition at 20 µM were identified, 66 of them plus 1 analog from a similarity search consistently displayed low IC50 values (<10 µM). In vitro experiments yielded 22 nontoxic hits that suppressed the tube formation of primary human umbilical vein ECs at 10 µM. Of them, 15 exhibited binding affinity to PFKFB3 in surface plasmon resonance assays, including 3 (WNN0403-E003, WNN1352-H007 and WNN1542-F004) that passed the pan-assay interference compounds screening without warning flags. This study provides potential leads to the development of new PFKFB3 inhibitors.

The H2S Donor NaHS Changes the Expression Pattern of H2S-Producing Enzymes after Myocardial Infarction.

Aims. To examine the expression patterns of hydrogen sulphide- (H2S-) producing enzymes in ischaemic heart tissue and plasma levels of H2S after 2 weeks of NaHS treatment after myocardial infarction (MI) and to clarify the role of endogenous H2S in the MI process. Results. After MI surgery, 2 weeks of treatment with the H2S donor NaHS alleviated ischaemic injury. Meanwhile, in ischemia myocardium, three H2S-producing enzymes, cystathionine γ-lyase (CSE), cystathionine-ß-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST) significantly increased. Plasma H2S levels were also elevated. In vitro, NaHS treatment protected cardiomyocytes from hypoxic injury and raised CBS levels in a concentration-dependent manner. Different from in vivo results, however, CSE or 3-MST expression did not change. NaHS treatment increased the activity of CSE/CBS but not of 3-MST. When CSE was either knocked down (in vitro) or knocked out (in vivo), H2S levels significantly decreased, which subsequently exacerbated the ischaemic injury. Meanwhile, the expressions of CBS and 3-MST increased due to compensation. Conclusions. Exogenous H2S treatment changed the expressions of three H2S-producing enzymes and H2S levels after MI, suggesting a new and indirect regulatory mechanism for H2S production and its contribution to cardiac protection. Endogenous H2S plays an important role in protecting ischaemic tissue after MI.

Hydrogen sulfide promotes angiogenesis by downregulating miR-640 via the VEGFR2/mTOR pathway.

We previously found hydrogen sulfide (H2S) to be a new proangiogenic factor. However, the mechanisms underlying the cardiovascular effect of this small gas molecule remain largely unknown. The aim of the present study was to identify the essential microRNAs (miRNAs) involved in the transduction of H2S signals in vascular endothelial cells (ECs). The expression of miR-640 and its signaling elements, vascular endothelial growth factor receptor 2 (VEGFR2), hypoxia inducible factor 1-α (HIF1A), and mammalian target of rapamycin (mTOR), was measured using quantitative PCR and Western blotting. Overexpression and inhibition of miR-640 were performed to clarify their roles in mediating the effect of H2S. In addition, knockdown of VEGFR2, HIF1A, and mTOR was performed using siRNAs, dominant negative mutants, or inhibitors to examine their roles in the transduction of the H2S signals. miR-640 levels decreased in vascular ECs that were treated with H2S, whereas overexpression of miR-640 blunted the proangiogenic effect of H2S. Knockdown of either VEGFR2 or mTOR blunted the downregulation of miR-640 and the proangiogenic effect induced by H2S. In addition, miR-640 bound to the 3'-UTR of HIF1A mRNA and then inhibited the expression of HIF1A. The inhibition could be recovered by treating cells with H2S. Thus we concluded that miR-640 plays a pivotal role in mediating the proangiogenic effect of H2S; H2S acts through downregulation of the expression of miR-640 and increasing the levels of HIF1A through the VEGFR2-mTOR pathway.

Cardiac H2S Generation Is Reduced in Ageing Diabetic Mice.

Aims. To examine whether hydrogen sulfide (H2S) generation changed in ageing diabetic mouse hearts. Results. Compared to mice that were fed tap water only, mice that were fed 30% fructose solution for 15 months exhibited typical characteristics of a severe diabetic phenotype with cardiac hypertrophy, fibrosis, and dysfunction. H2S levels in plasma, heart tissues, and urine were significantly reduced in these mice as compared to those in controls. The expression of the H2S-generating enzymes, cystathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase, was significantly decreased in the hearts of fructose-fed mice, whereas cystathionine-ß-synthase levels were significantly increased. Conclusion. Our results suggest that this ageing diabetic mouse model developed diabetic cardiomyopathy and that H2S levels were reduced in the diabetic heart due to alterations in three H2S-producing enzymes, which may be involved in the pathogenesis of diabetic cardiomyopathy.