Application of in-vitro screening methods on hypoxia inducible factor prolyl hydroxylase inhibitors

Silencing of topical proline hydroxylase domain 2 promotes the healing of rat diabetic wounds by phosphorylating AMPK

BACKGROUND

For diabetic ulcers, the impaired response to hypoxia is a key feature associated with delayed healing. In the early phase of hypoxia, hypoxic signaling activates the AMPK system through direct phosphorylation of the PHD2 pathway, producing a significant endogenous hypoxic protective effect.

METHODS

Twenty Sprague-Dawley (SD) rats were randomly divided into two groups: treatment (sh-PHD2) and control (sh-Control). Using lentiviral encapsulation of PHD2-shRNA and transfection, the silencing efficiency of PHD2 expression was verified in rat dermal fibroblasts (RDF) and in rat aortic endothelial cells (RAECs). Changes in the ability of RDF and RAECs to proliferate, migrate, and in the rate of ATP production were observed and then tested after inhibition of AMPK phosphorylation using dorsomorphin. The lentiviral preparation was injected directly into the wounds of rats and wound healing was recorded periodically to calculate the healing rate. Wounded tissues were excised after 14 days and the efficiency of PHD2 silencing, as well as the expression of growth factors, was examined using molecular biology methods. Histological examination was performed to assess CD31 expression and therefore determine effects on angiogenesis.

RESULTS

Lentiviral-encapsulated PHD2-sh-RNA effectively suppressed PHD2 expression and improved the proliferation, migration, and ATP production rate of RDF and RAEC, which were restored to their previous levels after inhibition of AMPK. The rate of wound healing, vascular growth, and expression of growth factors were significantly improved in diabetic-model rats after local silencing of PHD2 expression.

CONCLUSION

Silencing of PHD2 promoted wound healing in diabetic-model SD rats by activating AMPK phosphorylation.

Exploring the natural products chemical space through a molecular search to discover potential inhibitors that target the hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD)

Introduction: Hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD) enzymes are major therapeutic targets of anemia and ischemic/hypoxia diseases. To overcome safety issues, liver failure, and problems associated with on-/off-targets, natural products due to their novel and unique structures offer promising alternatives as drug targets. Methods: In the current study, the Marine Natural Products, North African, South African, East African, and North-East African chemical space was explored for HIF-PHD inhibitors discovery through molecular search, and the final hits were validated using molecular simulation and free energy calculation approaches. Results: Our results revealed that CMNPD13808 with a docking score of -8.690 kcal/mol, CID15081178 with a docking score of -8.027 kcal/mol, CID71496944 with a docking score of -8.48 kcal/mol and CID11821407 with a docking score of -7.78 kcal/mol possess stronger activity than the control N-[(4-hydroxy-8-iodoisoquinolin-3-yl)carbonyl]glycine, 4HG (-6.87 kcal/mol). Interaction analysis revealed that the target compounds interact with Gln239, Tyr310, Tyr329, Arg383 and Trp389 residues, and chelate the active site iron in a bidentate manner in PHD2. Molecular simulation revealed that these target hits robustly block the PHD2 active site by demonstrating stable dynamics. Furthermore, the half-life of the Arg383 hydrogen bond with the target ligands, which is an important factor for PHD2 inhibition, remained almost constant in all the complexes during the simulation. Finally, the total binding free energy of each complex was calculated as CMNPD13808-PHD2 -72.91 kcal/mol, CID15081178-PHD2 -65.55 kcal/mol, CID71496944-PHD2 -68.47 kcal/mol, and CID11821407-PHD2 -62.06 kcal/mol, respectively. Conclusion: The results show the compounds possess good activity in contrast to the control drug (4HG) and need further in vitro and in vivo validation for possible usage as potential drugs against HIF-PHD2-associated diseases.

A novel PHD2 inhibitor acteoside from Cistanche tubulosa induces skeletal muscle mitophagy to improve cancer-related fatigue

OBJECTIVE

To study whether ACT exerts anti-fatigue activity against CRF by inducing skeletal muscle mitophagy via suppressing PHD2 to upregulate the HIF-1α/BNIP3 signaling pathway.

METHODS

In this study, the molecular docking virtual screening technique was used to screen active components in Cistanche tubulosa that act as potential PHD2 inhibitors; the preliminary verification was carried out by Surface plasmon resonance (SPR) technology. BALB/c mice were treated with Paclitaxel (PTX, 10 mg/kg) and ACT (50, 100 mg/kg) alone or in combination for 20 days. Fatigue-related behaviors, energy metabolism and skeletal muscle mitochondria were assessed. Murine C2C12 myoblast was cultured and differentiated; then, a C26 tumor cell-conditioned medium was added to induce cachexia. Intracellular reactive oxygen species (ROS), mitochondrial membrane potential, mitochondrial microstructure and function, autophagy, PHD2/HIF-1 and PINK1/Parkin signal pathway proteins were analyzed. Then, interfering RNA technology was used to silence PHD2 and observe the efficacy of ACT.

RESULTS

We demonstrated that ACT exerted good binding activity with PHD2; ACT administration ameliorated PTX-induced muscle fatigue-like behavior via improving muscle quality and mitochondria function, increasing mitophagy, upregulating COXIV, CytoC, PINK1, Parkin, HIF-1α and BNIP3 expression and inhibiting p62, LC3B, PHD2 and Beclin-1 expression. The protective effect of ACT disappeared after transfection with the PHD2 gene knockdown plasmid Egln-1-RNAi.

CONCLUSIONS

These results suggest that ACT can improve CRF by promoting mitophagy via suppression of PHD2 to remove dysfunctional mitochondria, demonstrating that ACT has huge prospects for clinical application in CRF treatment.

Inhalation of sodium hydrosulfide (NaHS) alleviates NO2-induced pulmonary function and hematological impairment in rats

BACKGROUND

Inhalation of NO₂ leads to a progressive airflow limitation and the development of emphysema-like lesions. We report on the efficacy of hydrogen sulfide (NaHS) for alleviating NO₂-induced pulmonary impairment.

METHODS

Sprague Dawley rats were exposed to 20 ppm NO₂ for 6 h over six consecutive days for 75 days. At day 75, rats who had developed NO₂-induced emphysema were then divided into sodium hydrosulfide (NaHS) administrated group, placebo (NaCl) group and spontaneous recovery group for about one month (days 76-105); Pulmonary function (PF) and hematological and biochemical indices were measured at days 14, 45, 75, and 105.

RESULTS

NO₂ exposure for 75 days was associated with a significant decrease in FEV₁₀₀/FVC%, an increased in functional residual capacity (FRC), and histologic evidence of emphysema, moreover; NO₂ exposure led to elevated triglyceride (TG), red blood cell (RBC), hemoglobin (HGB), and hematocrit (HCT) levels. Impaired rats treated with NaHS showed no further deterioration in PF compared to rats exposed to ambient air and elevated WBC, granulocyte and lymphocyte counts and HDL-C levels to rats given NaCl.

CONCLUSIONS

NO₂ exposure causes emphysema and a decline in PF in rats. NaHS could alleviate the PF decline as possible indicated by an elevation of HDL-C levels and leukocyte. NaHS has therapeutic potential for emphysema caused by air pollutant NO₂.

Prolyl Hydroxylase Inhibitors: A Breakthrough in the Therapy of Anemia Associated with Chronic Diseases

Chronic kidney disease, cancer, chronic inflammatory disorders, nutritional, and genetic deficiency can cause anemia. Hypoxia causes induction of hypoxia-inducible factor (HIF), which stimulates erythropoietin (EPO) synthesis. Prolyl hydroxylase domain (PHD) enzyme inhibition can stabilize hypoxia-inducible factor (HIF). HIF stabilization also decreases hepcidin, a hormone of hepatic origin, which regulates iron homeostasis. PHD inhibitors represent a novel pharmacological treatment of anemia associated with chronic diseases. Many orally active PHD inhibitors like roxadustat, molidustat, vadadustat, and desidustat are in late phase clinical trials. This review discusses the role of PHD inhibitors in the treatment of anemia associated with chronic diseases.

MiR-21-mediated Metabolic Alteration of Cancer-associated Fibroblasts and Its Effect on Pancreatic Cancer Cell Behavior

In this study, we investigated whether the metabolic alteration of cancer-associated fibroblasts (CAFs) occurs via miR-21 remodeling and the effect of this alteration on pancreatic cancer cells. CAFs and normal fibroblasts (NFs) were isolated and cultured. Glucose consumption and lactic acid production were tested, and lactate dehydrogenase (LDHA), pyruvate kinase m2 (PKM2), and miR-21 expression were examined. The level of glycolysis in CAFs was determined after treatment with a miR-21 inhibitor. Primary miR-21-NC CAFs and miR-21-inhibitor CAFs were indirectly co-cultured with BxPc-3 in vitro, and the invasion capacity of these cells was determined. The aerobic oxidation index of cancer cells and the expression of succinodehydrogenase (SDH) and fumarate hydratase (FH) were assessed. Compared with NFs, CAFs showed enhanced glucose uptake capacity, lactic acid production, and elevated LDHA, PKM2, and miR-21 expression. After miR-21 inhibitor treatment, the extent of glycolysis in CAFs was reduced. After indirect co-culture with CAFs, oxidative phosphorylation and SDH, FH, and MCT expression increased in BxPc-3 cells. After co-culture with miR-21-inhibitor-CAFs, oxidative phosphorylation and invasion ability of the pancreatic cancer cells decreased. MiR-21 was involved in metabolic alteration of CAFs and affected the development of cancer cells. This metabolic alteration may be an important mechanism by which the microenvironment promotes tumor progression in a nonvascular manner.