Xanthine oxidase (XO) is an important source of reactive oxygen species. This study investigated whether XO inhibition exerts renoprotective effects by inhibiting vascular endothelial growth factor (VEGF) and NADPH oxidase (NOX) in diabetic kidney disease (DKD). Febuxostat (5 mg/kg) was administered to streptozotocin (STZ)-treated 8-week-old male C57BL/6 mice via intraperitoneal injection for 8 weeks. The cytoprotective effects, its mechanism of XO inhibition, and usage of high-glucose (HG)-treated cultured human glomerular endothelial cells (GECs) were also investigated. Serum cystatin C, urine albumin/creatinine ratio, and mesangial area expansion were significantly improved in febuxostat-treated DKD mice. Febuxostat reduced serum uric acid, kidney XO levels, and xanthine dehydrogenase levels. Febuxostat suppressed the expression of VEGF mRNA, VEGF receptor (VEGFR)1 and VEGFR3, NOX1, NOX2, and NOX4, and mRNA levels of their catalytic subunits. Febuxostat caused downregulation of Akt phosphorylation, followed by the enhancement of dephosphorylation of transcription factor forkhead box O3a (FoxO3a) and the activation of endothelial nitric oxide synthase (eNOS). In an in vitro study, the antioxidant effects of febuxostat were abolished by a blockade of VEGFR1 or VEGFR3 via NOX-FoxO3a-eNOS signaling in HG-treated cultured human GECs. XO inhibition attenuated DKD by ameliorating oxidative stress through the inhibition of the VEGF/VEGFR axis. This was associated with NOX-FoxO3a-eNOS signaling.

Cilastatin is a specific inhibitor of renal dehydrodipeptidase-1. We investigated whether cilastatin preconditioning attenuates renal ischemia-reperfusion (IR) injury via hypoxia inducible factor-1α (HIF-1α) activation. Human proximal tubular cell line (HK-2) was exposed to ischemia, and male C57BL/6 mice were subjected to bilateral kidney ischemia and reperfusion. The effects of cilastatin preconditioning were investigated both in vitro and in vivo. In HK-2 cells, cilastatin upregulated HIF-1α expression in a time- and dose-dependent manner. Cilastatin enhanced HIF-1α translation via the phosphorylation of Akt and mTOR was followed by the upregulation of erythropoietin (EPO) and vascular endothelial growth factor (VEGF). Cilastatin did not affect the expressions of PHD and VHL. However, HIF-1α ubiquitination was significantly decreased after cilastatin treatment. Cilastatin prevented the IR-induced cell death. These cilastatin effects were reversed by co-treatment of HIF-1α inhibitor or HIF-1α small interfering RNA. Similarly, HIF-1α expression and its upstream and downstream signaling were significantly enhanced in cilastatin-treated kidney. In mouse kidney with IR injury, cilastatin treatment decreased HIF-1α ubiquitination independent of PHD and VHL expression. Serum creatinine level and tubular necrosis, and apoptosis were reduced in cilastatin-treated kidney with IR injury, and co-treatment of cilastatin with an HIF-1α inhibitor reversed these effects. Thus, cilastatin preconditioning attenuated renal IR injury via HIF-1α activation.

Background: The serine/threonine protein kinase B (PKB/Akt) is involved in insulin signaling, cellular survival, and transformation. Carboxyl-terminal modulator protein (CTMP) has been identified as a novel PKB binding partner in a yeast two-hybrid screen, and appears to be a negative PKB regulator with tumor suppressor-like properties. In the present study we investigate novel mechanisms by which CTMP plays a role in apoptosis process.Results: CTMP is localized to mitochondria. Furthermore, CTMP becomes phosphorylated following the treatment of cells with pervanadate, an insulin-mimetic. Two serine residues (Ser37 and Ser38) were identified as novelin vivophosphorylation sites of CTMP. Association of CTMP and heat shock protein 70 (Hsp70) inhibits the formation of complexes containing apoptotic protease activating factor 1 and Hsp70. Overexpression of CTMP increased the sensitivity of cells to apoptosis, most likely due to the inhibition of Hsp70 function.Conclusion: Our data suggest that phosphorylation on Ser37/Ser38 of CTMP is important for the prevention of mitochondrial localization of CTMP, eventually leading to cell death by binding to Hsp70. In addition to its role in PKB inhibition, CTMP may therefore play a key role in mitochondria-mediated apoptosis by localizing to mitochondria.

Intratympanic (IT) injection of corticosteroids is a standard clinical treatment for sensorineural hearing loss; however, achieving both biocompatibility and efficient cochlea drug delivery remains a significant challenge. Herein, we engineered a novel drug nanocrystal (NS)-loaded thermo-reversible hydrogel (NS-TG) system of dexamethasone-21-palmitate (DEX-P), a lipophilic prodrug of dexamethasone (DEX), for improved IT delivery. NSs with a mean diameter of 835.0 nm were fabricated using a dual centrifugation process with polyvinyl alcohol as the stabilizer. The NS-TG system, comprising NSs in a 19% (w/v) Poloxamer 407 hydrogel, exhibited rapid gelation (2–3 min) and a 31-fold increase in drug solubility (1.57 ± 0.02 mg/mL) compared to NS alone, through micellar solubilization. In vitro cytotoxicity assays in HEI-OC1 cells revealed that NS-TG is highly biocompatible, maintaining cell viability, whereas the commercial lipid emulsion (Lipothason^®) induced significant cytotoxicity. In vivo pharmacokinetic evaluation in mice revealed that IT NS-TG provided superior cochlear drug absorption compared to DEX-SP solutions and DEX-P NS, despite showing lower absorption than the lipid emulsion. These findings suggest that the DEX-P NS-TG system, pending further investigation, could serve as a promising platform for cochlear steroidal delivery, offering an optimal balance between delivery efficiency and local safety for treating inner ear diseases.

Renal lipotoxicity and oxidative stress are major contributors to diabetic kidney disease (DKD), but the role of proprotein convertase subtilisin/kexin type 9 (PCSK9) and its relationship with AMP-activated protein kinase (AMPK) signaling remain unclear. We investigated the effects of PCSK9 inhibition on renal lipotoxicity and oxidative stress in db/db mice and high-glucose (HG)-treated HK-2 cells using a selective PCSK9 inhibitor (PCSK9i) with or without AMPKα1/α2 small interfering RNA (siRNA). PCSK9i significantly reduced albuminuria, renal injury, histopathological changes, and intrarenal lipid accumulation without altering glycemic control. These effects were accompanied by increased low-density lipoprotein receptor (LDLR) expression, reduced cluster of differentiation 36 (CD36) expression, enhanced AMPK phosphorylation and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) expression, reduced sterol regulatory element-binding protein-1c (SREBP-1c) expression, restored carnitine palmitoyltransferase 1 (CPT1) expression, modulated protein kinase B (Akt)/forkhead box O (FoxO) signaling, and reduced oxidative stress and apoptosis. Similar findings were observed in HG-treated HK-2 cells. Importantly, AMPK knockdown attenuated the protective effects of PCSK9i on lipid metabolism, oxidative stress, and apoptosis in HK-2 cells. PCSK9 inhibition attenuates renal lipotoxicity and oxidative stress in DKD, providing a preclinical rationale for further investigation of the renal metabolic effects of PCSK9-directed therapies and their association with AMPK activation.

Lung cancer remains one of the most common and lethal malignancies worldwide, with poor prognosis largely due to late-stage diagnosis and resistance to therapy. Emerging evidence indicates that long non-coding RNAs (lncRNAs) play critical roles in cancer development, metastasis, and treatment resistance. Particulate matter (PM), a major environmental pollutant and recognized Group 1 carcinogen, has been linked to lung cancer through mechanisms that may involve dysregulation of lncRNA expression. This study aimed to identify PM-responsive lncRNAs in lung cancer, and investigate their potential functional roles. Microarray analysis of lung cancer cell lines A549, H358, H292, and HCC827, exposed to PM10, revealed significant up-regulation of lnc-MTPAP-1. TUNEL staining confirmed that silencing of lnc-MTPAP-1 via siRNA resulted in increased apoptosis across all tested lines. Transcriptome analysis using next-generation sequencing showed that knockdown of lnc-MTPAP-1 altered the expression of apoptosis-related genes, with up-regulation of TNS4, MyD88, and IL6R, and down-regulation of CLPTM1L and EI24. These findings suggest that lnc-MTPAP-1 may exert anti-apoptotic effects in lung cancer cells, and be involved in pollution-induced cancer progression. Further research should explore the therapeutic potential of targeting lnc-MTPAP-1, and better understand the molecular impact of PM exposure on lung cancer pathogenesis.