Upregulation Of HIF-1α Expression Research Articles

Mulberroside A attenuates cigarette smoke-induced atherosclerosis in ApoE−/− mice via the Sirt1-HIF-1α axis

ObjectiveThis study investigated whether Mulberryside A (MBA) can attenuate cigarette smoke extract (CSE)-induced autophagy through a Sirt1-dependent pathway, thereby attenuating atherosclerosis in ApoE−/− mice. MethodsAfter treating human umbilical vein endothelial cells (HUVECs) with CSE and MBA, an MTT assay was performed to detect cell activity. Immunofluorescence and Western blotting were used to determine the expressions of autophagy-related proteins, Sirt1 and HIF-1α. Lentivirus and siRNA were used to construct overexpression and silencing (Sirt1 and HIF-1α) models. The in vivo inflammatory effects of CS on atherosclerosis in ApoE−/− mice were assessed by exposing mice to CS and MBA treatment. HE staining was used to detect atherosclerosis in mouse aortic tissue, and electron microscopy was used to detect autophagy of endothelial cells. ResultsCSE promoted autophagy in HUVECs, down-regulated Sirt1, and up-regulated HIF-1α expression. MBA treatment, overexpression of Sirt1, or silencing of HIF-1α attenuated CSE-induced autophagy, while MBA reversed CSE-induced downregulation of Sirt1 and upregulation of HIF-1α. However, overexpression of HIF-1α increased autophagy in HUVECs and attenuated the protective effect of Sirt1 overexpression or MBA on CSE-induced autophagy in HUVECs. In vivo experiments also demonstrated that MBA attenuates CS-induced aortic autophagy in ApoE−/− mice and up-regulates Sirt1 and downregulates HIF-1α expression. ConclusionsMBA attenuates CSE-induced autophagy through the Sirt1-HIF-1α axis, thereby attenuating atherosclerosis in ApoE−/− mice.

Oxygen-controllable injectable hydrogel alleviates intervertebral disc degeneration by balancing extracellular matrix metabolism

Nucleus pulposus (NP) cells, situated at the core of intervertebral discs, have acclimated to a hypoxic environment, orchestrating the equilibrium of extracellular matrix metabolism (ECM) under the regulatory influence of hypoxia inducible factor-1α (HIF-1α). Neovascularization and increased oxygen content pose a threat, triggering ECM degradation and intervertebral disc degeneration (IVDD). To address this, our study devised an oxygen-controllable strategy, introducing laccase into an injectable and ultrasound-responsive gelatin/agarose hydrogel. Laccase-mediated reactions were employed to deplete oxygen, establishing a hypoxic microenvironment that upregulated HIF-1α expression. The activation of hypoxia-inducible factors significantly enhanced the expression of aggrecan and collagen II, concurrently suppressing Matrix metalloproteinases (MMP13) and A Disintegrin and Metalloproteinase with Thrombospondin motifs (ADAMTS5) levels, thereby restoring the equilibrium of ECM metabolism. Simultaneously, the hydrogel facilitated the recruitment of stem cells into the NP through the controlled release of ATI2341, activating C-X-C chemokine receptor type 4 (CXCR4). Moreover, ultrasound amplification enhanced ATI2341 release, promoting the migration of NP stem cells. The hydrogel's efficacy in mitigating metabolic imbalances and inhibiting IVDD progression was substantiated in a rat puncture IVDD model through hydrogel injection into the discs. In conclusion, this hypoxia-inducible hydrogel, responsive to thermal stimuli from ultrasound, presents a promising avenue for IVDD treatment.

Targeting metabolic reprogramming to overcome drug resistance in advanced bladder cancer: insights from gemcitabine- and cisplatin-resistant models.

Gemcitabine plus cisplatin (GC) combination chemotherapy is the primary treatment for advanced bladder cancer (BC) with unresectable or metastatic disease. However, most cases develop resistance to this therapy. We investigated whether drug resistance could be targeted through metabolic reprogramming therapies. Metabolomics analyses in our lab's gemcitabine- and cisplatin-resistant cell lines revealed increased phosphoglycerate dehydrogenase (PHGDH) expression in gemcitabine-resistant cells compared with parental cells. Isocitrate dehydrogenase 2 (IDH2) gain of function stabilized hypoxia-inducible factor1α (HIF1α) expression, stimulating aerobic glycolysis. In gemcitabine-resistant cells, elevated fumaric acid suppressed prolyl hydroxylase domain-containing protein 2/Egl nine homolog 1 (PHD2) and stabilized HIF1α expression. PHGDH downregulation or inhibition in gemcitabine-resistant BC cells inhibited their proliferation, migration, and invasion. Cisplatin-resistant cells showed elevated fatty acid metabolism, upregulating fatty acid synthase (FASN) downstream of tyrosine kinase. Using the fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor erdafitinib, we inhibited malonyl-CoA production, which is crucial for fatty acid synthesis, and thereby suppressed upregulated HIF1α expression. Combination treatment with NCT503 and erdafitinib synergistically suppressed tumor cell proliferation and induced apoptosis in vitro and in vivo. Understanding these mechanisms could enable innovative BC therapeutic strategies to be developed.

Role of transforming growth factor-β1 pathway in angiogenesis induced by chronic stress in colorectal cancer

ABSTRACT Background Chronic stress can induce stress-related hormones; norepinephrine (NE) is considered to have the highest potential in cancer. NE can stimulate the expression of hypoxia-inducible factor-1α (HIF-1α), which is associated with vascular endothelial growth factor (VEGF) secretion and tumor angiogenesis. However, the underlying mechanisms are poorly understood. Methods Tumor-bearing mice were subjected to chronic restraint stress and treated with normal saline, human monoclonal VEGF-A neutralizing antibody bevacizumab, or β-adrenergic receptor (β-AR) antagonist (propranolol). Tumor growth and vessel density were also evaluated. Human colorectal adenocarcinoma cells were treated with NE, propranolol, or the inhibitor of transforming growth factor-β (TGF-β) receptor Type I kinase (Ly2157299) in vitro. TGF-β1 in mouse serum and cell culture supernatants was quantified using ELISA. The expression of HIF-1α was measured using Real time-PCR and western blotting. Cell migration and invasion were tested. Results Chronic restraint stress attenuated the efficacy of bevacizumab and promoted tumor growth and angiogenesis in a colorectal tumor model. Propranolol blocked this effect and inhibited TGF-β1 elevation caused by chronic restraint stress or NE. NE upregulated HIF-1α expression, which was reversed by propranolol or Ly2157299. Propranolol and Ly2157199 blocked NE-stimulated cancer cell migration and invasion. Conclusions Our results demonstrate the effect of NE on tumor angiogenesis and the critical role of TGF-β1 signaling during this process. In addition, β-AR/TGF-β1 signaling/HIF-1α/VEGF is a potential signaling pathway. This study also indicates that psychosocial stress might be a risk factor which weakens the efficacy of anti-angiogenic therapy.

An E3 ligase TRIM1 promotes colorectal cancer progression via K63-linked ubiquitination and activation of HIF1α

Accumulating studies have shown that E3 ligases play crucial roles in regulating cellular biological processes and signaling pathways during carcinogenesis via ubiquitination. Tripartite-motif (TRIM) ubiquitin E3 ligases consist of over 70 members. However, the clinical significance and their contributions to tumorigenesis remain largely unknown. In this study, we analyzed the RNA-sequencing expression of TRIM E3 ligases in colorectal cancer (CRC) and identified 10 differentially expressed genes, among which TRIM1 expression predicted poor prognosis of CRC patients. We demonstrated that TRIM1 expression is positively associated with CRC pathological stages, and higher expression is positively correlated with infiltrating levels of immune cells and immunotherapy biomarkers. TRIM1 expression promotes the proliferation and migration of colorectal cancer cells in vitro and in vivo. Transcriptional analysis showed that TRIM1 is responsible for metabolism promotion and immune suppression. Mechanistically, we found that TRIM1 binds HIF1α and mediates its K63-linked ubiquitination, which is required for HIF1α nuclear translocation and subsequent activation. Ubiquitination occurs at Lys214 in the loop between the two PAS domains of HIF1α, and mutation of Lys214 severely disturbs the function of HIF1α. Besides, HIF1α ubiquitination enhances its binding with proteins involved in cellular trafficking and nucleocytoplasmic transport pathway. Collectively, our results indicate TRIM1’s role in predicting prognosis and reveal how TRIM1 functions to upregulate HIF1α expression and promote tumor cell proliferation.

Oxygen tension regulating hydrogels for vascularization and osteogenesis via sequential activation of HIF-1α and ERK1/2 signaling pathways in bone regeneration

Angiogenesis plays a crucial role in bone regeneration. Hypoxia is a driving force of angiogenesis at the initial stage of tissue repair. The hypoxic microenvironment could activate the hypoxia-inducible factor (HIF)-1α signaling pathway in cells, thereby enhancing the proliferation, migration and pro-angiogenic functions of stem cells. However, long-term chronic hypoxia could inhibit osteogenic differentiation and even lead to apoptosis. Therefore, shutdown of the HIF-1α signaling pathway and providing oxygen at later stage probably facilitate osteogenic differentiation and bone regeneration. Herein, an oxygen tension regulating hydrogel that sequentially activate and deactivate the HIF-1α signaling pathway were prepared in this study. Its effect and mechanism on stem cell differentiation were investigated both in vitro and in vivo. We proposed a gelatin-based hydrogel capable of sequentially delivering a hypoxic inducer (copper ions) and oxygen generator (calcium peroxide). The copper ions released from the hydrogels significantly enhanced cell viability and VEGF secretion of BMSCs via upregulating HIF-1α expression and facilitating its translocation into the nucleus. Additionally, calcium peroxide promoted alkaline phosphatase activity, osteopontin secretion, and calcium deposition through the activation of ERK1/2. Both Cu2+ and calcium peroxide demonstrated osteogenic promotion individually, while their synergistic effect within the hydrogels led to a superior osteogenic effect by potentially activating the HIF-1α and ERK1/2 signaling pathways.

M2 Tumor-Associated Macrophages-Derived Exosomal MALAT1 Promotes Glycolysis and Gastric Cancer Progression.

M2-polarized tumor-associated macrophages (M2 TAMs) promote cancer progression. Exosomes mediate cellular communication in the tumor microenvironment (TME). However, the roles of exosomes from M2 TAMs in gastric cancer progression are unclear. Herein, it is reported that M2 TAMs-derived exosomes induced aerobic glycolysis in gastric cancer cells and enhanced their proliferation, metastasis, and chemoresistance in a glycolysis-dependent manner. It is identified that MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) is enriched in M2 TAM exosomes and confirmed that MALAT1 transfer from M2 TAMs to gastric cancer cells via exosomes mediates this effect. Mechanistically, MALAT1 interacted with the δ-catenin protein and suppressed its ubiquitination and degradation by β-TRCP. In addition, MALAT1 upregulated HIF-1α expression by acting as a sponge for miR-217-5p. The activation of β-catenin and HIF-1α signaling pathways by M2 TAM exosomes collectively led to enhanced aerobic glycolysis in gastric cancer cells. Finally, a dual-targeted inhibition of MALAT1 in both gastric cancer cells and macrophages by exosome-mediated delivery of siRNA remarkably suppressed gastric cancer growth and improved chemosensitivity in mouse tumor models. Taken together, these results suggest that M2 TAMs-derived exosomes promote gastric cancer progression via MALAT1-mediated regulation of glycolysis. The findings offer a potential target for gastric cancer therapy.

HIV coinfection exacerbates HBV-induced liver fibrogenesis through a HIF-1α- and TGF-β1-dependent pathway

Persons with chronic HBV infection coinfected with HIV experience accelerated progression of liver fibrosis compared to those with HBV monoinfection. We aimed to determine whether HIV and its proteins promote HBV-induced liver fibrosis in HIV/HBV-coinfected cell culture models through HIF-1α and TGF-β1 signaling. The HBV-positive supernatant, purified HBV viral particles, HIV-positive supernatant, or HIV viral particles were directly incubated with cell lines or primary hepatocytes, hepatic stellate cells, and macrophages in mono or 3D spheroid coculture models. Cells were incubated with recombinant cytokines and HIV proteins including gp120. HBV sub-genomic constructs were transfected into NTCP-HepG2 cells. We also evaluated the effects of inhibitor of HIF-1α and HIV gp120 in a HBV carrier mouse model that was generated via hydrodynamic injection of the pAAV/HBV1.2 plasmid into the tail vein of wild-type C57BL/6 mice. We found that HIV and HIV gp120, through engagement with CCR5 and CXCR4 coreceptors, activate AKT and ERK signaling and subsequently upregulate hypoxia-inducible factor-1α (HIF-1α) to increase HBV-induced transforming growth factor-β1 (TGF-β1) and profibrogenic gene expression in hepatocytes and hepatic stellate cells. HIV gp120 exacerbates HBV X protein-mediated HIF-1α expression and liver fibrogenesis, which can be alleviated by inhibiting HIF-1α. Conversely, TGF-β1 upregulates HIF-1α expression and HBV-induced liver fibrogenesis through the SMAD signaling pathway. HIF-1α small-interfering RNA transfection or the HIF-1α inhibitor (acriflavine) blocked HIV-, HBV-, and TGF-β1-induced fibrogenesis. Our findings suggest that HIV coinfection exacerbates HBV-induced liver fibrogenesis through enhancement of the positive feedback between HIF-1α and TGF-β1 via CCR5/CXCR4. HIF-1α represents a novel target for antifibrotic therapeutic development in HBV/HIV coinfection. HIV coinfection accelerates the progression of liver fibrosis compared to HBV monoinfection, even among patients with successful suppression of viral load, and there is no sufficient treatment for this disease process. In this study, we found that HIV viral particles and specifically HIV gp120 promote HBV-induced hepatic fibrogenesis via enhancement of the positive feedback between HIF-1α and TGF-β1, which can be ameliorated by inhibition of HIF-1α. These findings suggest that targeting the HIF-1α pathway can reduce liver fibrogenesis in patients with HIV and HBV coinfection.

E. Coli LPS-induced calcium signaling regulates the expression of hypoxia-inducible factor 1α in periodontal ligament fibroblasts in a non-hypoxia-dependent manner

Periodontitis, an inflammatory disease, can cause significant damage to the oral tissues which support the teeth. During the early development of periodontitis, periodontal ligament fibroblasts (PDLFs) undergo metabolic reprogramming regulated by hypoxia-inducible factor 1α (HIF-1α), which is strongly linked to the progression of inflammation. However, the precise mechanisms by which PDLFs regulate HIF-1α and its associated metabolic reprogramming during early inflammation remain unclear. This study illustrated that brief and low-dose exposure to Escherichia coli (E. coli) lipopolysaccharide (LPS) can serve as a non-hypoxic stimulus, effectively replicating early periodontal inflammatory reactions. This is evidenced by the upregulation of HIF-1α expression and the activation of HIF-1α-mediated crucial glycolytic enzymes, namely lactate dehydrogenase a, pyruvate kinase, and hexokinase 2, concomitant with an augmentation in the inflammatory response within PDLFs. We observed that the effects mentioned and their impact on macrophage polarization were notably attenuated when intracellular and extracellular stores of Ca2+ were depleted using BAPTA-AM and Ca2+-free medium, respectively. Mechanistically, our findings demonstrated that the transcriptional process of HIF-1α is regulated by Ca2+ during E. coli LPS stimulation, mediated through the signal transducer and activator of transcription 3 (STAT3) pathway. Additionally, we observed that the stabilization of intracellular HIF-1α proteins occurs via the endothelin (ET)-1-endothelin A receptor pathway, independent of hypoxia. Taken together, our research outcomes underscore the pivotal involvement of Ca2+ in the onset of early periodontitis by modulating HIF-1α and glycolysis, thereby presenting novel avenues for early therapeutic interventions.

Intermittent Hypobaric Hypoxia Ameliorates Autistic-Like Phenotypes in Mice.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and stereotyped behaviors. Although major advances in basic research on autism have been achieved in the past decade, and behavioral interventions can mitigate the difficulties that individuals with autism experience, little is known about the many fundamental issues of the interventions, and no specific medication has demonstrated efficiency for the core symptoms of ASD. Intermittent hypobaric hypoxia (IHH) is characterized by repeated exposure to lowered atmospheric pressure and oxygen levels, which triggers multiple physiological adaptations in the body. Here, using two mouse models of ASD, male Shank3B -/- and Fmr1 -/y mice, we found that IHH training at an altitude of 5,000 m for 4 h per day, for 14 consecutive days, ameliorated autistic-like behaviors. Moreover, IHH training enhanced hypoxia inducible factor (HIF) 1α in the dorsal raphe nucleus (DRN) and activated the DRN serotonergic neurons. Infusion of cobalt chloride into the DRN, to mimic IHH in increasing HIF1α expression or genetically knockdown PHD2 to upregulate HIF1α expression in the DRN serotonergic neurons, alleviated autistic-like behaviors in Shank3B -/- mice. In contrast, downregulation of HIF1α in DRN serotonergic neurons induced compulsive behaviors. Furthermore, upregulating HIF1α in DRN serotonergic neurons increased the firing rates of these neurons, whereas downregulation of HIF1α in DRN serotonergic neurons decreased their firing rates. These findings suggest that IHH activated DRN serotonergic neurons via upregulation of HIF1α, and thus ameliorated autistic-like phenotypes, providing a novel therapeutic option for ASD.

Aberrantly expressed HIF-1α enhances HCC stem cell-like traits via Wnt/β-catenin signaling activation after insufficient radiofrequency ablation.

Radiofrequency ablation has become a favorable treatment modality for small hepatocellular carcinoma (HCC) recently; however, insufficient radiofrequency ablation (RFA) was shown to lead to enhanced invasiveness and metastasis of HCC in our previous study, while the underlying molecular mechanism has not been understood. In order to explore the influence of the hypoxic microenvironment on residual cancer and cancer stem cell (CSC)-like characteristics of HCC cells in this process, an in vitro hypoxic model and an insufficient RFA mouse model were established with HCC cancer cell lines. Immunochemistry staining and western blot were used to examine the expression of hypoxia-inducible factor (HIF)-1α and liver CSC markers. The 3D colon formation assay, tumor cell invasion assay, and gene transfection assays were applied to test the change in liver CSC stemness and HCC cell invasion. After insufficient RFA treatment, the upregulated HIF-1α expression was associated with an increase in the CSC-like population in residual cancer. In vitro, hypoxic tumor cells showed aggressive CSC-like properties and phenotypes. Wnt/β-catenin signaling activation was shown to be necessary for the acquisition of liver CSC-like characteristics under hypoxic conditions. Overall, the aberrantly enhanced HIF-1α expression enhanced the liver CSC-like traits via abnormal Wnt/β-catenin signaling activation after insufficient RFA, and the overexpressed HIF-1α would be a vital factor and useful biomarker during the HCC recurrence and metastasis.

Lysyl oxidase inhibits BMP9-induced osteoblastic differentiation through reducing Wnt/β-catenin via HIF-1a repression in 3T3-L1 cells

BackgroundBone morphogenetic protein 9 (BMP9) is a promising growth factor in bone tissue engineering, while the detailed molecular mechanism underlying BMP9-oriented osteogenesis remains unclear. In this study, we investigated the effect of lysyl oxidase (Lox) on the BMP9 osteogenic potential via in vivo and in vitro experiments, as well as the underlying mechanism.MethodsPCR assay, western blot analysis, histochemical staining, and immunofluorescence assay were used to quantify the osteogenic markers level, as well as the possible mechanism. The mouse ectopic osteogenesis assay was used to assess the impact of Lox on BMP9-induced bone formation.ResultsOur findings suggested that Lox was obviously upregulated by BMP9 in 3T3-L1 cells. BMP9-induced Runx2, OPN, and mineralization were all enhanced by Lox inhibition or knockdown, while Lox overexpression reduced their expression. Additionally, the BMP9-induced adipogenic makers were repressed by Lox inhibition. Inhibition of Lox resulted in an increase in c-Myc mRNA and β-catenin protein levels. However, the increase in BMP9-induced osteoblastic biomarkers caused by Lox inhibition was obviously reduced when β-catenin knockdown. BMP9 upregulated HIF-1α expression, which was further enhanced by Lox inhibition or knockdown, but reversed by Lox overexpression. Lox knockdown or HIF-1α overexpression increased BMP9-induced bone formation, although the enhancement caused by Lox knockdown was largely diminished when HIF-1α was knocked down. Lox inhibition increased β-catenin levels and decreased SOST levels, which were almost reversed by HIF-1α knockdown.ConclusionLox may reduce the BMP9 osteoblastic potential by inhibiting Wnt/β-catenin signaling via repressing the expression HIF-1α partially.Graphical abstract

Circ_ZNF778_006 promoted ESCC progression by upregulating HIF-1α expression via sponging miR-18b-5p

In multiple malignant tumors, circular RNAs (circRNAs) are believed to play a crucial role. Our prior results demonstrated that circ_ZNF778_006 was significantly increased in esophageal squamous cell carcinoma (ESCC) tissues, but the roles of circ_ZNF778_006 in ESCC is still not clear. The expression of circ_ZNF778_006 was compared in different pathological grades of ESCC. And the expression levels of circ_ZNF778_006, miR-18b-5p, HIF-1α were analyzed by qRT-PCR and Western blot, respectively. Plasmid transfection techniques were applied to prepare ESCC cells with silenced or overexpressed genes (CircZNF778_006, miR-18b-5p). The CCK8 kit was used to determine cell proliferation, and the Transwell assay was used to measure the migration and invasion. The effects of circ_ZNF778_006 on tumor growth was investigated in vivo. Furthermore, luciferase reporter gene assay and RNA-binding protein immunoprecipitation (RIP) were performed to verify the targeting relationship between miR-18b-5p and circZNF778_006, miR-18b-5p and HIF-1α. The expression of circ_ZNF778_006 was positively correlated with pathological grade in ESCC. Circ_ZNF778_006 significantly inhibited sensitivity to 5-fluorouracil & cisplatin. It could promote the proliferation, invasion, migration in ESCC cells and accelerated tumor growth in vivo. Furthermore, circ_ZNF778_006 could upregulate the expression of HIF-1α via sponing miR-18b-5p. Circ_ZNF778_006 promoted ESCC progression by upregulating HIF-1α expression via sponging miR-18b-5p.

HIF-1α-Dependent Autophagy Deficiency in Bone Marrow Endothelial Progenitor Cells Contributes to Acute Graft-Versus-Host Disease after Allotransplant

Background: Acute Graft-Versus-Host Disease (aGVHD) constitutes a prevalent component after allogeneic hematopoietic stem cell transplantation(allo-HSCT). Among the components of the Bone Marrow（BM)microenvironment, Endothelial Progenitor Cells (EPCs) hold significant importance in hematopoietic-supporting and immune reconstitution in post-transplantation patients. Consequently, a discernible correlation emerges between the impairment of EPCs and the incidence and severity of GVHD. Our recent study has shown impaired EPC function and heightened reactive oxygen species (ROS) levels in aGVHD patients (2018, BJH). Additionally, reduced levels of hypoxia-inducible factor-1α (HIF-1α) and autophagy were observed in BM EPCs from aGVHD patients in comparison to those without GVHD（non-GVHD）. HIF-1α is closely linked to ROS generation. Therefore， exploring the role of HIF-1α and autophagy in the development of aGVHD after allo-HSCT is significant. Aims： To conduct a comparative analysis of the functions of EPCs and assess the variations in the expression levels of HIF-1α and autophagy-related proteins between aGVHD and non-GVHD patients. Additionally, the study aims to assess whether the low HIF-1α level is responsible for the autophagy deficiency and mitochondrial dysfunction observed in EPCs of aGVHD patients, and to delineate the specific pathways through which this downregulation influences their capacity of hematopoiesis-supporting. Methods: The current prospective clinical case-matched study included 20 patients with aGVHD and 40 patients without GVHD. BM mononuclear cells（BMMNCs） were cultured as former publications reported. EPCs（CD34+, CD133+, CD309+) were flow-sorted for evaluating apoptosis, ROS, and autophagy levels. SiRNA transfection knocked down HIF-1α in human umbilical vein endothelial cells (HUVECs). Endothelial cells(ECs） gene expression levels were determined using Western blot, RT-qPCR. ECs function was assessed by angiogenesis, Transwell cell migration, CCK-8 cell proliferation, and JC-1 mitochondrial staining. ECs were co-cultured with hematopoietic stem cells （HSCs） for seven days, and HSCs were subjected to colony-forming unit assays and other experiments to evaluate hematopoietic stem cell function. ECs NAD+ and NADH levels were assessed by the kit. Results: Downregulation of autophagy signaling pathway in HUVECs following knockdown of HIF-1α, leading to inhibited cell proliferation, migration, and angiogenesis. Similarly, patients affected by aGVHD exhibited reduced HIF-1α expression, impaired autophagy, and cellular function in EPCs compared to non-GVHD patients. HSCs co-culturing with HUVECs with HIF-1α knockdown and EPCs from aGVHD patients resulted in increased apoptosis, elevated levels of ROS, and impaired colony formation ability. However, intervention with HIF-1α activators Roxadustat, which served to upregulate HIF-1α levels in ECs, activated autophagy, and improved cellular function, also enhanced the hematopoiesis-supporting ability. Furthermore, the knockdown of HIF-1α in HUVECs and EPCs of aGVHD patients led to the abnormal activation of SIRT1 and PARP1 and other NAD+-consuming proteins, which subsequently caused a decrease in NAD+ levels and resulted in abnormal mitochondrial membrane potential. The supplementation of NAD+ precursors, specifically β-nicotinamide mononucleotide, effectively increased NAD+ levels in ECs and restored cellular function. Conclusion: The results revealed that the autophagy deficiency was mediated by reduced expression of HIF-1α in EPCs of patients with aGVHD. The deficiency of autophagy also led to abnormal activation of SIRT1 and PARP1, which in turn affected the levels of NAD+ and mitochondrial membrane potential, ultimately impairing cellular function and hematopoiesis-supporting ability. These molecular changes may be identified as potential contributors to the pathogenesis of aGVHD after allo-HSCT. On the other hand, Roxadustat upregulates HIF-1α expression in ECs, which subsequently enhanced the autophagy level and improved mitochondrial function. As a result, cellular function and hematopoiesis-supporting ability were restored. This promising therapeutic approach highlights a novel strategy for preventing and treating of patients with aGVHD after allo-HSCT.

Vav1-dependent Rac1 activation mediates hypoxia-induced gemcitabine resistance in pancreatic ductal adenocarcinoma cells through upregulation of HIF-1α expression.

Hypoxia has been shown to induce gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC) cells, however, the underlying mechanisms remain to be clarified. In the present study, we investigated whether activation of Vav1/Rac1/HIF-1α axis is responsible for hypoxia-induced GEM resistance in PDAC cells. Our results showed that Rac1 activation contributed to hypoxia-induced GEM resistance in PANC-1 cells. Hypoxia treatment led to an increased expression level of Vav1, which was responsible for Rac1 activation and GEM resistance in PDAC cells. Furthermore, Rac1 mediated hypoxia-induced GEM resistance by upregulating HIF-1α in PDAC cells. Taken together, these findings suggest that hypoxia induces GEM resistance in PDAC cells by activating the Vav1/Rac1/HIF-1α signaling pathway.

LuQi Formula relieves ventricular remodeling through improvement of HIF-1α-mediated intestinal barrier integrity

BackgroundVentricular remodeling is the adaptive process in which the heart undergoes changes due to stress, leading to heart failure (HF). The progressive decline in cardiac function is considered to contribute to intestinal barrier impairment. LuQi Formula (LQF) is a traditional Chinese medicine preparation widely used in the treatment of ventricular remodeling and HF. However, the role of LQF in the impairment of intestinal barrier function induced by ventricular remodeling remains unclear.Materials and methodsVentricular remodeling was induced in rats by permanently ligating the left anterior descending branch coronary artery, and cardiac function indexes were assessed using echocardiography. Heart and colon tissue morphology were observed by hematoxylin–eosin, Masson’s trichrome and Alcian Blue Periodic acid Schiff staining. Myocardial cell apoptosis was detected using TUNEL and immunohistochemistry. Circulatory levels of brain natriuretic peptide (BNP), intestinal permeability markers endotoxin, D-lactate and zonulin, as well as inflammatory cytokines tumor necrosis factor alpha and interleukin-1 beta were measured by Enzyme-linked immunosorbent assay. Expression levels of tight junction (TJ) proteins and hypoxia-inducible factor-1 alpha (HIF-1α) in colon tissue were detected by immunofluorescence, immunohistochemistry and western blotting. Cardiac function indexes and intestinal permeability markers of patients with HF were analyzed before and after 2–4 months of LQF treatment.ResultsLQF protected cardiac function and alleviated myocardial fibrosis and apoptosis in rats with ventricular remodeling. LQF protected the intestinal barrier integrity in ventricular remodeling rats, including maintaining colonic tissue morphology, preserving the number of goblet cells and normal expression of TJ proteins. Furthermore, LQF upregulated the expression of HIF-1α protein in colon tissue. Intervention with a HIF-1α inhibitor weakened the protective effect of LQF on intestinal barrier integrity. Moreover, a reduction of HIF-1α aggravated ventricular remodeling, which could be alleviated by LQF. Correspondingly, the circulating levels of intestinal permeability markers and BNP in HF patients were significantly decreased, and cardiac function markedly improved following LQF treatment.ConclusionsWe demonstrated that LQF effectively protected cardiac function by preserving intestinal barrier integrity caused by ventricular remodeling, at least partially through upregulating HIF-1α expression.

Dual FGFR and VEGFR inhibition synergistically restrain hexokinase 2-dependent lymphangiogenesis and immune escape in intrahepatic cholangiocarcinoma

BackgroundTherapies for cholangiocarcinoma are largely limited and ineffective. Herein, we examined the role of the FGF and VEGF pathways in regulating lymphangiogenesis and PD-L1 expression in intrahepatic cholangiocarcinoma (iCCA).MethodsThe lymphangiogenic functions of FGF and VEGF were evaluated in lymphatic endothelial cells (LECs) and iCCA xenograft mouse models. The relationship between VEGF and hexokinase 2 (HK2) was validated in LECs by western blot, immunofluorescence, ChIP and luciferase reporter assays. The efficacy of the combination therapy was assessed in LECs and xenograft models. Microarray analysis was used to evaluate the pathological relationships of FGFR1 and VEGFR3 with HK2 in human lymphatic vessels.ResultsFGF promoted lymphangiogenesis through c-MYC-dependent modulation of HK2 expression. VEGFC also upregulated HK2 expression. Mechanistically, VEGFC phosphorylated components of the PI3K/Akt/mTOR axis to upregulate HIF-1α expression at the translational level, and HIF-1α then bound to the HK2 promoter region to activate its transcription. More importantly, dual FGFR and VEGFR inhibition with infigratinib and SAR131675 almost completely inhibited lymphangiogenesis, and significantly suppressed iCCA tumor growth and progression by reducing PD-L1 expression in LECs.ConclusionsDual FGFR and VEGFR inhibition inhibits lymphangiogenesis through suppression of c-MYC-dependent and HIF-1α-mediated HK2 expression, respectively. HK2 downregulation decreased glycolytic activity and further attenuated PD-L1 expression. Our findings suggest that dual FGFR and VEGFR blockade is an effective novel combination strategy to inhibit lymphangiogenesis and improve immunocompetence in iCCA.

Nicotine activates HIF-1α and regulates acid extruders through the nicotinic acetylcholine receptor to promote the Warburg effect in non-small cell lung cancer cells

Cigarette smoking is the greatest risk factor for lung cancer, accounting for approximately 90% of all lung cancer-related deaths. Moreover, nicotine is associated with lung cancer onset and progression. Hypoxia-inducible factor 1α (HIF-1α) is involved in the metabolic reprogramming of cancer cells and accelerates cancer progression via regulation of pH and acid–base homeostasis. Previous studies have reported that nicotine upregulates HIF-1α expression. Therefore, we hypothesized that nicotine-mediated activation of HIF-1α regulates metabolic reprogramming and pH homeostasis in non-small cell lung cancer A549 cells and could potentially play a role in the progression of lung cancer. We examined the effects of nicotine on metabolic reprogramming and intracellular pH (pHi) homeostasis, which are critical for cancer progression. A549 cells were exposed to nicotine in the absence and presence of the nicotinic acetylcholine receptor antagonist, mecamylamine (MEC). We then analyzed glycolytic stress and the activity and expression of acid-extruder proteins, including the Na+–H+ exchanger 1 (NHE1) and monocarboxylate cotransporters 1 & 4 (MCT1 and MCT4, respectively). Nicotine promoted the Warburg effect, which is associated with accelerated migration of A549 cells through the activation of nicotinic acetylcholine receptors. Furthermore, nicotine upregulated the activities and expression of acid-extruder proteins, namely NHE1 and MCT4, and facilitated glycolysis. To the best of our knowledge, this is the first study to demonstrate that nicotine plays a pivotal regulatory role in metabolic reprogramming as well as regulation of pHi homeostasis in A549 cells via activation of nicotinic acetylcholine receptors and can therefore aggravate lung cancer progression.

Hypoxia promotes conversion to a stem cell phenotype in prostate cancer cells by activating HIF-1α/Notch1 signaling pathway.

The hypoxic tumor microenvironment and the maintenance of stem cells are relevant to the malignancy of prostate cancer (PCa). However, whether HIF-1α in the hypoxic microenvironment mediates the transformation of prostate cancer to a stem cell phenotype and the mechanism have not been elucidated. Prostate cancer stem cells (PCSCs) from PC-3 cell lines were examined for the expression of CD44, CD133, ALDH1, HIF-1α, Notch1, and HES1. We observed the effect of knockdown HIF-1α in vitro and mice models and evaluated the impact of HIF-1α on the Notch1 pathway as well as stem cell dedifferentiation. The effects on sphere formation, cell proliferation, apoptosis, cell cycle, and invasive metastasis were evaluated. In our study, hypoxia upregulated HIF-1α expression and induced a stem cell phenotype through activation of the Notch1 pathway, leading to enhanced proliferation, invasion, and migration of PCa PC-3 cells. The knockdown of HIF-1α significantly inhibited cell dedifferentiation and the ability to proliferate, invade and metastasize. However, the inhibitory effect of knocking down HIF-1α was reversed by Jagged1, an activator of the Notch1 pathway. These findings were further confirmed in vivo, where hypoxia could enhance the tumorigenicity of xenograft tumors by upregulating the expression of HIF-1α to activate the Notch1 pathway. In addition, the expression of HIF-1α and Notch1 was significantly increased in human PCa tissues, and high expression of HIF-1α correlated with the malignancy of PCa. In a hypoxic environment, HIF-1α promotes PCa cell dedifferentiation to stem-like cell phenotypes by activating the Notch1 pathway and enhancing the proliferation and invasive capacity of PC-3 cells.

NR4A1 enhances glycolysis in hypoxia-exposed pulmonary artery smooth muscle cells by upregulating HIF-1α expression

NR4A1 enhances glycolysis in hypoxia-exposed pulmonary artery smooth muscle cells by upregulating HIF-1α expression