In this study according to the critical pharmacophore T
In this study, according to the critical pharmacophore T31, Y113 and R140 of FBPase, using the strategy of pharmacophore-based virtual screening, a series of novel scaffold inhibitor targeted the AMP binding site of FBPase were screened, their inhibitory activities against FBPase were further tested. Among these compounds, the 15 H12 exhibit highest inhibitions with the IC50 value of 13.6 μM. Then, the analogues of H12 was obtained from the SPECs database. In comparison, compound H27 exhibited highest inhibitory activities with the IC50 value of 5.3 μM. The SAR analysis of these compounds demonstrated that the benzene ring of R1 position and the furan part are the indispensable elements for the binding to FBPase. The possible binding conformation of compound H27 and FBPase was identified by using DOX2.0 strategy. The potential pharmacophores of FBPase were further studied by site-directed mutagenesis and enzymatic assays. Moreover, according the compound H27 binding model, compound H29 were further optimized and found by using the structure-guided drug design method. As expected, compound H29 shows highest inhibition activity with the IC50 value of 2.5 μM. The agreement between theory and experiment suggest that the interactional information of hit compound and FBPase were reliable. Especially, we present a discovery method of novel scaffold inhibitors against FBPase, which are different from previous AMP analogues. We expected that these hit compounds can reduce the possibility of side effects causing by AMP analogues. The present positive results indicated that the methods adopted in present study will be a promising road to further develop FBPase inhibitors and clarify the chemical biology studies of T2D.
Gluconeogenesis in Cancer Gluconeogenesis (see Glossary) generates free glucose from non-carbohydrate carbon substrates such as glycerol, lactate, pyruvate, and glucogenic amino acids. Although being relatively less investigated than catabolic glycolysis or oxidative phosphorylation (OXPHOS), this anabolic pathway plays an equal role in controlling aerobic glycolysis by cancer cells. The complete pathway consists of 11 enzyme-catalyzed reactions, and with exception of seven reactions that belong to the reverse steps of glycolysis, the other reactions are exclusive for gluconeogenesis, including: (i) the conversion of pyruvate to phosphoenolpyruvate, catalyzed by pyruvate carboxylase (PC) and PEPCK; (ii) the conversion of fructose-1,6-bisphosphate to fructose-6-phosphate, catalyzed by FBPase; and (iii) the conversion of glucose-6-phosphate to glucose, catalyzed by G6Pase. PEPCK, FBPase, and G6Pase are key enzymes that control the gluconeogenic flux, and thus influence glycolysis, the tricarboxylic acid (TCA) cycle, the pentose phosphate pathway (PPP), and other branched metabolic pathways (serine biosynthesis, glyceroneogenesis, glycogenesis, glutaminolysis, cataplerosis, and anaplerosis) (Figure 1). The expression of these enzymes is regulated by several transcriptional factors (FOXO1, CREB, Nur77, HNF-4α, C/EBPα, and PPARγ) and coactivators (PGC-1α, CBP, CRTC2, SRC-1, and PRMTs) 1, 2, 3, 4. Some oncogenes or tumor suppressors control this expression through interaction with these molecules. Cancer cells display a high rate of glycolysis even in the presence of oxygen, a phenomenon known as aerobic glycolysis or the Warburg effect. This maintains sufficient glycolytic intermediates and NADPH for cell proliferation by promoting glycolysis and its branched pathways 5, 6. Hence, regulating metabolic reprogramming may represent an Achilles’ heel of cancer. The gluconeogenesis pathway is usually inhibited in cancers because it antagonizes glycolysis. However, the expression of gluconeogenic enzymes may not parallel the level of gluconeogenesis because some types of cancers may engage in truncated gluconeogenesis to support their biosynthetic needs, and the function of key enzymes is likely dissociated from glucose production that operates in fasting conditions . Some isoforms of key gluconeogenic enzymes are distributed ubiquitously rather than being restricted to gluconeogenic organs (liver and kidney), and have other biological functions beyond gluconeogenesis. For instance, PEPCK acts as a cataplerotic enzyme to support tumors under nutrient depletion by utilizing non-carbohydrate precursors for anabolic biosynthesis 7, 8, 9; FBPase functions as a transcriptional corepressor in the nucleus via suppressing HIF-1α activity, triggering a switch from aerobic glycolysis to OXPHOS 10, 11. These intricate metabolic and non-metabolic roles of gluconeogenic enzymes determine their aberrant expression in multiple types of tumors, making them potential therapeutic targets.