Thymoquinone affects hypoxia-inducible factor-1αexpression in pancreatic cancer cells via HSP90 and PI3K/AKT/mTOR pathways

BACKGROUND Pancreatic cancer(PC)is associated with some of the worst prognoses of all major cancers.Thymoquinone(TQ)has a long history in traditional medical practice and is known for its anti-cancer,anti-inflammatory,anti-fibrosis and antioxidant pharmacological activities.Recent studies on hypoxia-inducible factor-1α(HIF-1α)and PC have shown that HIF-1αaffects the occurrence and development of PC in many aspects.In addition,TQ could inhibit the development of renal cancer by decreasing the expression of HIF-1α.Therefore,we speculate whether TQ affects HIF-1αexpression in PC cells and explore the mechanism.AIM To elucidate the effect of TQ in PC cells and the regulatory mechanism of HIF-1αexpression.METHODS Cell counting kit-8 assay,Transwell assay and flow cytometry were performed to detect the effects of TQ on the proliferative activity,migration and invasion ability and apoptosis of PANC-1 cells and normal pancreatic duct epithelial(hTERTHPNE)cells.Quantitative real-time polymerase chain reaction and western blot assay were performed to detect the expression of HIF-1αmRNA and protein in PC cells.The effects of TQ on the HIF-1αprotein initial expression pathway and ubiquitination degradation in PANC-1 cells were examined by western blot assay and co-immunoprecipitation.RESULTS TQ significantly inhibited proliferative activity,migration,and invasion ability and promoted apoptosis of PANC-1 cells;however,no significant effects on hTERT-HPNE cells were observed.TQ significantly reduced the mRNA and protein expression levels of HIF-1αin PANC-1,AsPC-1,and BxPC-3 cells.TQ significantly inhibited the expression of the HIF-1αinitial expression pathway(PI3K/AKT/mTOR)related proteins,and promoted the ubiquitination degradation of the HIF-1αprotein in PANC-1 cells.TQ had no effect on the hydroxylation and von Hippel Lindau protein mediated ubiquitination degradation of the HIF-1αprotein but affected the stability of the HIF-1αprotein by inhibiting the interaction between HIF-1αand HSP90,thus promoting its ubiquitination degradation.CONCLUSION The regulatory mechanism of TQ on HIF-1αprotein expression in PC cells was mainly to promote the ubiquitination degradation of the HIF-1αprotein by inhibiting the interaction between HIF-1αand HSP90;Secondly,TQ reduced the initial expression of HIF-1αprotein by inhibiting the PI3K/AKT/mTOR pathway.

Hypoxia-inducible factor 1alpha and vascular endothelial growth factor in Glioblastoma Multiforme:a systematic review going beyond pathologic implications

Glioblastoma multiforme(GBM)is an aggressive primary brain tumor characterized by extensive heterogeneity and vascular proliferation.Hypoxic conditions in the tissue microenvironment are considered a pivotal player leading tumor progression.Specifically,hypoxia is known to activate inducible factors,such as hypoxia-inducible factor 1alpha(HIF-1α),which in turn can stimulate tumor neo-angiogenesis through activation of various downward mediators,such as the vascular endothelial growth factor(VEGF).Here,we aimed to explore the role of HIF-1α/VEGF immunophenotypes alone and in combination with other prognostic markers or clinical and image analysis data,as potential biomarkers of GBM prognosis and treatment efficacy.We performed a systematic review(Medline/Embase,and Pubmed database search was completed by 16th of April 2024 by two independent teams;PRISMA 2020).We evaluated methods of immunoassays,cell viability,or animal or patient survival methods of the retrieved studies to assess unbiased data.We used inclusion criteria,such as the evaluation of GBM prognosis based on HIF-1α/VEGF expression,other biomarkers or clinical and imaging manifestations in GBM related to HIF-1α/VEGF expression,application of immunoassays for protein expression,and evaluation of the effectiveness of GBM therapeutic strategies based on HIF-1α/VEGF expression.We used exclusion criteria,such as data not reporting both HIF-1αand VEGF or prognosis.We included 50 studies investigating in total 1319 GBM human specimens,18 different cell lines or GBM-derived stem cells,and 6 different animal models,to identify the association of HIF-1α/VEGF immunophenotypes,and with other prognostic factors,clinical and macroscopic data in GBM prognosis and therapeutic approaches.We found that increased HIF-1α/VEGF expression in GBM correlates with oncogenic factors,such as miR-210-3p,Oct4,AKT,COX-2,PDGF-C,PLDO3,M2 polarization,or ALK,leading to unfavorable survival.Reduced HIF-1α/VEGF expression correlates with FIH-1,ADNP,or STAT1 upregulation,as well as with clinical manifestations,like epileptogenicity,and a favorable prognosis of GBM.Based on our data,HIF-1αor VEGF immunophenotypes may be a useful tool to clarify MRI-PET imaging data distinguishing between GBM tumor progression and pseudoprogression.Finally,HIF-1α/VEGF immunophenotypes can reflect GBM treatment efficacy,including combined first-line treatment with histone deacetylase inhibitors,thimerosal,or an active metabolite of irinotecan,as well as STAT3 inhibitors alone,and resulting in a favorable tumor prognosis and patient survival.These data were supported by a combination of variable methods used to evaluate HIF-1α/VEGF immunophenotypes.Data limitations may include the use of less sensitive detection methods in some cases.Overall,our data support HIF-1α/VEGF’s role as biomarkers of GBM prognosis and treatment efficacy.

Wortmannin influences hypoxia-inducible factor-1 alpha expression and glycolysis in esophageal carcinoma cells

AIM: To investigate the influence of phosphatidylinositol-3-kinase protein kinase B(PI3K/AKT)-HIF-1α signaling pathway on glycolysis in esophageal carcinoma cells under hypoxia. METHODS: Esophageal carcinoma cell lines Eca109 and TE13 were cultured under hypoxia environment, and the protein, m RNA and activity levels of hypoxia inducible factor-1 alpha(HIF-1α), glucose transporter 1, hexokinase-Ⅱ, phosphofructokinase 2 and lactate dehydrogenase-A were determined. Supernatant lactic acid concentrations were also detected. The PI3K/AKT signaling pathway was then inhibited with wortmannin, and the effects of hypoxia on the expression or activities of HIF-1α, associated glycolytic enzymes and lactic acid concentrations were observed. Esophageal carcinoma cells were then transfected with interference plasmid with HIF-1α-targeting si RNA to assess impact of the high expression of HIF-1α on glycolysis.RESULTS: HIF-1α is highly expressed in the esophageal carcinoma cell lines tested, and with decreasing levels of oxygen, the expression of HIF-1α and the associated glycolytic enzymes and the extracellular lactic acid concentration were enhanced in the esophageal carcinoma cell lines Eca109 and TE13. In both normoxia and hypoxic conditions, the level of glycolytic enzymesand the secretion of lactic acid were both reduced by wortmannin. The expression and activities of glycolytic enzymes and the lactic acid concentration in cells were reduced by inhibiting HIF-1α, especially the decreasing level of glycolysis was significant under hypoxic conditions.CONCLUSION: The PI3K/AKT pathway and HIF-1α are both involved in the process of glycolysis in esophageal cancer cells.

Is the hypoxia-inducible factor-1 alpha mRNA expression activated by ethanol-induced injury, the mechanism underlying alcoholic liver disease?

BACKGROUND: Excessive alcohol consumption can result in multiple organ injury, of which alcoholic liver disease (ALD) is the most common. With economic development and improvement of living standards, the incidence of diseases caused by alcohol abuse has been increasing in China, although its pathogenesis remains obscure. The aim of this study was to investigate the role of hypoxia in chronic ALD. METHODS: Twenty-eight male Sprague-Dawley rats were randomized into a control group (n=12) with a normal history and an experimental group (n=16) fed with 10 ml/ kg of 56% (vol/vol) ethanol once per day by gastric lavage for 24 weeks. At 24 weeks, blood samples were collected and then the rats were killed. Liver samples were frozen at -80 ℃ and used for RT-PCR; other liver samples were obtained for immunohistochemical staining. RESULTS: When the period of alcohol consumption increased, the positive rate of expression of hypoxia- inducible factor-1 alpha (HIF-1α) mRNA was more significantly elevated in the liver of the alcohol group than in the control group (P≤0.05). The HIF-1α protein located in the cytoplasm was seldom expressed in the control group, but significantly in the alcohol group (P≤0.01). CONCLUSION: HIF-1α mRNA expression was activated by ethanol-induced injury in this study, suggesting that hypoxia is involved in the underlying mechanism of ALD.

Clinicopathological and Prognostic Significance of Hypoxia-inducible Factor-1 alpha in Lung Cancer: a Systematic Review with Meta-analysis

Hypoxia-inducible factor-1 alpha（HIF-1α） plays a vital role in the initiation, evaluation and prognosis in lung cancer. The prognostic value of HIF-1α reported in diverse study remains disputable. Accordingly, a meta-analysis was implemented to further understand the prognostic role of HIF-1α in lung cancer. The relationship between HIF-1α and the clinicopathological characteristics and prognosis of lung cancer were investigated by a meta-analysis. Pub Med and Embase were searched from their inception to January 2015 for observational studies. Fixed-effects or random-effects meta-analyses were used to calculate odds ratios and 95% confidence intervals of different comparisons. A total of 20 studies met the criteria. The results showed that HIF-1α expression in lung cancer tissues was significantly higher than that in normal lung tissues. Expression of HIF-1α in patients with squamous cell carcinoma was significantly higher than that of patients with adenocarcinomas. Similarly, non-small cell lung cancer（NSCLC） patients had higher HIF-1α expression than small cell lung cancer（SCLC） patients. Moreover, lymph node metastasized tissues had higher HIF-1α expression than non-lymph node metastasized tissues. A high level HIF-1α expression was well correlated with the expression of vascular endothelial growth factor and epidermal growth factor receptor in the NSCLC. Notably, NSCLC or SCLC patients with positive HIF-1α expression in tumor tissues had lower overall survival rate than patients with negative HIF-1α expression. It was suggested that HIF-1α expression may be a prognostic biomarker and a potential therapeutic target for lung cancer.

Adenovirus-mediated hypoxia-inducible factor-1 alpha gene transfer induces angiogenesis and neurogenesis following cerebral ischemia in rats

BACKGROUND： Hypoxia-inducible factor-1 （HIF-1） accumulates under conditions of hypoxia. HIF-1α target genes have pleiotropic effects on neurogenesis, neuroprotection and angiogenesis in the brain. OBJECTIVE： To investigate whether a recombinant adenovirus carrying HIF-1α can increase the expression of HIF-I a in vivo and thus promote angiogenesis and neurogenesis in a rat model of focal cerebral ischemia. DESIGN, TIME AND SETTING： The randomized, controlled experiment was performed at the Department of Neurobiology, Third Military Medical University of Chinese PLA from September 2006 to October 2007. MATERIALS： 68 healthy adult male Sprague-Dawley （SD） rats, weighing 230-250 g, were used. HIF-I a antibody was purchased from Wuhan Boster Company. Vascular endothelial growth factor （VEGF） antibody was purchased from Santa Cruz Biotech Company. METHODS： All 68 rats were induced with a transient middle cerebral artery occlusion （MCAO）, according to the method of intra-luminal vascular occlusion. 54 rats, in which MCAO was successfully induced, were randomly divided into adenovirus （Ad） group and recombinant adenovirus with HIF-1α gene （Ad-HIF-1α ） group （27 rats for each group）. Rats were injected with 10 μL Ad （Ad group） or Ad-HIF-1α （Ad-HIF-1α group） into the lateral ventricle, 1 day after MCAO induction. MAIN OUTCOME MEASURES： Reverse transcription polymerase chain reaction was used to measure the expression of HIF-1α and of VEGF. Immunohistochemistry was used to detect the localization of HIF-1α, VEGF and factor Ⅷ in ischemic penumbra. Rat newborn nerve cells were labeled with 5-bromodeoxyuridine （BrdU） after ischemia. BrdU/neurofilament 200 （NF200） and BrdU/glial fibrillary acidic protein （GFAP） double labeled immunofluorescent histochemistry was used to identify the differentiation of newborn cells. Neurological function was evaluated using the modified neurological severity score （NSS）. RESULTS： Compared with Ad, Ad-HIF-1α enhanced the expression of HIF-1α and VEGF （P 〈 0.01）. The numbers of factor VIII, BrdU, BrdU/NF200 and BrdU/GFAP positive cells were increased significantly （P 〈 0.01） in the Ad-HIF-I a group compared to the Ad group. Levels of HIF-1α and VEGF mRNA in the Ad-HIF-1α group were enhanced compared with those in the Ad group. NSS scores of the Ad-HIF-1α group were superior to those of the Ad group at days 7, 14, 21, and 28 after MCAO （P 〈 0.05）. CONCLUSION： HIF-1α gene therapy can increase angiogenesis and neurogenesis, and thus improve neurological function following cerebral ischemia in rats.

Correlation of hypoxia-inducible factor-1 alpha and erythropoietin protein and mRNA to cerebral ischemic tolerance in a focal ischemia/reperfusion model using the twice suture method

BACKGROUND： Numerous studies have shown that transient ischemic preconditioning induces cerebral ischemic tolerance. However, the underlying mechanisms of endogenous protection following ischemic preconditioning remain unclear. OBJECTIVE： To dynamically measure erythropoietin and hypoxia-inducible factor-1α （HIF-1α） mRNA and protein expression at various times following preconditioning, and to investigate effects of erythropoietin and HIF-1α on cerebral ischemic tolerance in a model of focal ischemia/reperfusion established using the twice suture method. DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the Institute of Anatomy, Medical College, Qingdao University, China from March 2006 to March 2007. MATERIALS： Rabbit anti-rat HIF-1α monoclonal antibody and biotinylated goat anti-rabbit IgG （Boster, China）, rabbit anti-rat erythropoietin monoclonal antibody （Santa Cruz Biotechnology, USA）, and one-step RT-PCR kit （Qiagen, Germany） were used in this study. METHODS： A total of 99 healthy, male, Wistar rats were randomly assigned to three groups： sham surgery （n = 9）, non-ischemic preconditioning （n = 45）, and ischemic preconditioning （n = 45）. In the ischemic preconditioning group, rat models of pre-ischemia-reperfusion-ischemia-reperfusion were established by occluding the left middle cerebral artery using the twice suture method. In the non-ischemic preconditioning group, pre-ischemia was replaced by sham surgery. Subsequently, the ischemic preconditioning and non-ischemic preconditioning groups were equally divided into five subgroups according to time of first reperfusion, including 1-, 3-, 7-, 14-, and 21-day subgroups. The sham surgery group received the sham surgery twice. MAIN OUTCOME MEASURES： HIF-la and erythropoietin protein expression was measured in the cerebral cortex, corpus striatum, and hippocampus of the ischemic hemisphere. HIF-1α and erythropoietin mRNA expression were determined in the frontal and parietal cortex of the ischemic hemisphere. RESULTS： （1） Intergroup comparison： compared with the non-ischemic preconditioning group, HIF-1α protein expression significantly increased in the rat cerebral cortex, corpus striatum, and hippocampus in the ischemic hemisphere at 1,3, and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05 or P 〈 0.01）. Erythropoietin protein expression significantly increased in the cerebral cortex, corpus striatum, and hippocampus, as well as HIF-1α and erythropoietin mRNA expression in the frontal and parietal cortex in the ischemic hemisphere, at 3 and 7 days following reperfusion in the ischemic preconditioning group （P 〈 0.05）. （2） Temporal expression： HIF-1α protein expression in the rat cerebral cortex, corpus striatum, and hippocampus, as well as HIF-la mRNA expression in the frontal and parietal cortex, in the ischemic hemisphere increased at 3 days, and gradually decreased from 7 days following reperfusion in the ischemic preconditioning group. Temporal erythropoietin protein and mRNA expression was consistent with HIF-1α protein expression. （3） Correlation： erythropoietin mRNA expression positively correlated with HIF-1α mRNA expression （r= 0.737, P 〈 0.01）. CONCLUSION： Ischemic preconditioning induced cerebral ischemic tolerance. Pre-ischemiainduced increase in endogenous HIF-1αexpression, as well as its target gene erythropoietin, participated in the formation of cerebral ischemic tolerance.

Role of Hypoxia-inducible Factor-1α in Formation of Muttidrug Resistance Induced by Microenvironment in Hepatocellular Carcinoma

Objective： To explore the role of hypoxia-inducible factor-1α （HIF-1α） in formation of multidrug resistance （MDR） induced by microenvironment and to find a new and effective molecular target on preventing and reversing chemoresistance in hepatocellular carcinoma （HCC）. Methods： In HepG2 cells exposed to hypoxia, low glucose or transfected by plasmid pcDNA3/HBX, the expression of HIF-1α mRNA and protein was respectively detected using real-time fluorescent quantitative PCR and Westernblot technique and its expression localization was investigated by immunocytochemical technique. Plasmid pcDNA3/HIF-1α was transfected into HepG2 cells and then the expression of multidrug resistance related genes mdrl, multidrug resistance-associated protein 1 （MRP1） and lung resistance protein （LRP） in transfected cells was determined by the same methods. Results： In HepG2 cells respectively exposed to hypoxia, low glucose or transfected by plasmid pcDNA3/HBX, HIF-1α was overexpressed at mRNA and protein levels to varying degrees and translocated into nucleus. The gene expression levels of mdrl, MRP1 and LRP in HepG2 cells transfected by plasmid pcDNA3/HIF-1α were respectively increased by 2.4±0.2, 2.2±0.3 and 2.3±0.4 folds as compared with those in non-transfected HepG2 cells （all P〈0.01） and similar changes were observed in protein level. Conclusion： Microenvironmental factors around HCC could modulate the transcription of the MDR related genes by nuclear transcript factor HIF-1α, thereby conferred MDR of HCC. Up-regulation of HIF-1α expression could hold a central position in the formation of MDR of HCC induced by microenvironment. HIF-1α probably becomes a new and effective molecular target on preventing and reversing MDR in HCC.

Phosphatase and tensin homology deleted in chromosome 10,hypoxia-inducible factor-1 alpha gene expression in colorectal adenoma and adenocarcinoma and their relation to vascular endothelial growth factor protein expression

To examine phosphatase and tensin homology deleted in chromosome 10 (PTEN),hypoxia-inducible factor-1 alpha (HIF-1 alpha) gene expressions and their relation to vascular endothelial growth factor(VEGF) protein expression in the patients with human colorectal adenomas and adenocarcinomas.Methods The expression of PTEN,HIF-1 alpha gene was detected by using in situ hybridization,and the VEGF expression levels by immunohistochemistry in colorectal adenomas and primary colorectal adenocarcinoma.Results Strong expression of HIF-1 alpha was detectable in the majority of colorectal dadenocarcinoma,particularly surrounding areas of necrosis in adenocarcinoma.PTEN,HIF-1 alpha mRNA and VEGF protein were positive in 51.6%,67.7% and 59.7% respectively in 62 cases of adenocarcinomas,and 77.8%,44.4% and 33.3% respectively in 18 cases of adenomas.The positive rate of VEGF was higher in the patients with colorectal adenocarcinomas than that in those with adenomas,whereas that of PTEN mRNA was contrary.HIF-1 mRNA expression was correlated significantly with lymph node metastasis,liver metastasis,Duke’s stage and recurrence.During colorectal tumor progression,the expression of HIF-1 alpha mRNA was positively correlated with the VEGF protein expression (χ2= 4.751 ,P<0.05),but negatively with the PTEN mRNA expression(χ2=21.84,P<0.01).Conclusion The absence or low expression of PTEN and the increased levels of HIF-1α and VEGF may paly an important role in carcinogenesis and progression of colorectal carcinoma.These results suggest that VEGF upregulated by HIF-1 alpha gene may be involved in angiogenesis of colorectal adenocarcinoma.4 refs,1 tab.

Expression and clinical significance of CD73 and hypoxia-inducible factor-1α in gastric carcinoma

AIM: To investigate the expression of CD73 and hypoxia-inducible factor-1α (HIF-1α) in human gastric carcinoma, and explore their clinical significance and prognostic value. METHODS: CD73 and HIF-1α expressions were detected by immunohistochemistry in consecutive sections of tissue samples from 68 gastric carcinoma patients. The peritumor tissues 2 cm away from the tumor were obtained and served as controls. The presence of CD73 and HIF-1α was analyzed by immunohis-tochemistry using the Envision technique. RESULTS: CD73 and HIF-1α expressions in gastric carcinoma were significantly higher than those in gastric mucosal tissues as control (P < 0.001) and showed a close correlation (Spearman r = 0.390, P = 0.001). Overexpression of CD73 was positively correlated with differentiation of tumor (P = 0.000), histopathology (P = 0.041), depth of invasion (P < 0.001), nodal status (P = 0.003), metastasis (P = 0.013), and the American Joint Committee on Cancer (AJCC) stage (P < 0.001). High expression of HIF-1α was positively correlated with tumor diameter (P = 0.031), depth of invasion (P = 0.022), and AJCC stage (P = 0.035). The overall survival rate was low in the patients with high expression of CD73 (P < 0.001). Moreover, CD73+/HIF-1α+ patients had the worst prognosis (P < 0.001). CD73 expression was proven to be an independent predictor for patients with gastric carcinoma by both multivariate Cox regression analysis (P = 0.021) and receiver operating characteristic curves (P = 0.001).CONCLUSION: CD73 expression correlates closely with HIF-1α expression in gastric carcinoma. CD73 could be an independent prognostic indicator for gastric carcinoma.

Hypoxia-inducible factor-1 modulates upregulation of mutT homolog-1 in colorectal cancer

AIM: To investigate the roles and interactions of mut T homolog(MTH)-1 and hypoxia-inducible factor(HIF)-1α in human colorectal cancer(CRC).METHODS: The expression and distribution of HIF-1α and MTH-1 proteins were detected in human CRC tissues by immunohistochemistry and quantitative realtime polymerase chain reaction(q RT-PCR). SW480 and HT-29 cells were exposed to normoxia or hypoxia. Protein and m RNA levels of HIF-1α and MTH-1 were analyzed by western blotting and q RT-PCR, respectively. In order to determine the effect of HIF-1α on the expression of MTH-1 and the amount of 8-oxodeoxyguanosine triphosphate(d GTP) in SW480 and HT-29 cells, HIF-1α was silenced with small interfering RNA(si RNA). Growth studies were conducted on cells with HIF-1α inhibition using a xenograft tumor model. Finally, MTH-1 protein was detected by western blotting in vivo.RESULTS: High MTH-1 m RNA expression was detected in 64.2% of cases(54/84), and this was significantly correlated with tumor stage(P = 0.023) and size(P = 0.043). HIF-1α protein expression was correlated significantly with MTH-1 expression(R = 0.640; P < 0.01) in human CRC tissues. Hypoxic stress induced m RNA and protein expression of MTH-1 in SW480 and HT-29 cells. Inhibition of HIF-1α by si RNA decreased the expression of MTH-1 and led to the accumulation of 8-oxo-d GTP in SW480 and HT-29 cells. In the in vivo xenograft tumor model, expression of MTH-1 was decreased in the HIF-1α si RNA group, and the tumor volume was much smaller than that in the mock si RNA group.CONCLUSION: MTH-1 expression in CRC cells was upregulated via HIF-1α in response to hypoxic stress, emphasizing the crucial role of HIF-1α-induced MTH-1 in tumor growth.

Hypoxia-inducible factor 1 alpha and vascular endothelial growth factor overexpression in ischemic colitis

AIM: To examine the etiology and pathophysiology in human ischemic colitis from the viewpoint of ischemic factors such as hypoxia-inducible factor 1 alpha (HIF-1 alpha and vascular endothelial growth factor (VEGF). METHODS: Thirteen patients with ischemic colitis and 21 normal controls underwent colonoscopy. The follow-up colonoscopy was performed in 8 patients at 7 to 10 d after the occurrence of ischemic colitis. Biopsy samples were subjected to real-time RT-PCR and immunohistochemistry to detect the expression of HIF-1 alpha and VEGF. RESULTS: HIF-1 alpha and VEGF expression were found in the normal colon tissues by RT-PCR and immunohistochemistry. HIF-1 alpha and VEGF were overexpressed in the lesions of ischemic colitis. Overexpressed HIF-1 alpha and VEGF RNA quickly decreased to the normal level in the scar regions at 7 to 10 d after the occurrence of ischemic colitis. CONCLUSION: Constant expression of HIF-1 alpha and VEGF in normal human colon tissue suggested that HIF-1 alpha and VEGF play an important role in maintaining tissue integrity. We confirmed the ischemic crisis in ischemic colitis at the molecular level, demonstrating overexpression of HIF-1 alpha and VEGF in ischemic lesions. These ischemic factors may play an important role in the pathophysiology of ischemic colitis.

The hypoxia-inducible factor-1α activates ectopic production of fibroblast growth factor 23 in tumor-induced osteomalacia

Tumor-induced osteomalacia （TIO） is a rare paraneoplastic syndrome in which ectopic production of fibroblast growth factor 23 （FGF23） by non-malignant mesenchymal tumors causes phosphate wasting and bone fractures. Recent studies have implicated the hypoxia-inducible factor-la （HIF-la） in other phosphate wasting disorders caused by elevated FGF23, including X-linked hypophosphatemic rickets and autosomal dominant hypophosphatemia. Here we provide evidence that HIF-la mediates aberrant FGF23 in TIO by transcriptionally activating its promoter. Immunohistochemical studies in phosphaturic mesenchymal tumors resected from patients with documented TIO showed that HIF-la and FGF23 were co-localized in spindle- shaped cells adjacent to blood vessels. Cultured tumor tissue produced high levels of intact FGF23 and demonstrated increased expression of HIF-la protein. Transfection of MC3T3-E1 and Saos-2 cells with a HIF-la expression construct induced the activity of a FGF23 reporter construct. Prior treatment of tumor organ cultures with HIF-la inhibitors decreased HIF-la and FGF23 protein accumulation and inhibited HIF-la-induced luciferase reporter activity in transfected cells. Chromatin immunoprecipitation assays confirmed binding to a HIF-la consensus sequence within the proximal FGF23 promoter, which was eliminated by treatment with a HIF-la inhibitor. These results show for the first time that HIF-la is a direct transcriptional activator of FGF23 and suggest that upregulation of HIF-la activity in TIO contributes to the aberrant FGF23 production in these patients.

Association of hypoxia-inducible factor-1α (HIF1α) 1772C/T genepolymorphism with susceptibility to renal cell carcinoma/prostatecancer

In this study,we used a meta-analysis method to evaluate the relationship between hypoxia-inducible factor-1α(HIF1α)1772C/T gene polymorphism(rs 11549465)and renal cell carcinoma(RCC)/prostate cancer risk.We searched for relevant studies(before March 1,2019)on Cochrane Library,Embase,and PubMed.Studies meeting the inclusion criteria were recruited into this meta-analysis.The outcome of dichotomous data was showed in the way of odds ratios(OR),and 95%confidence intervals(CI)were also counted.In this investigation,there was no association between HIF1α1772C/T gene polymorphism and susceptibility to RCC in Caucasians,Asians as well as overall populations.In addition,HIF1α1772C/T gene polymorphism was not found to be relevant to the survival in RCC.Interestingly,the T allele was relevant to prostate cancer risk in all populations,but not in Caucasians and Asians.However,the TT genotype and the CC genotype were not related to prostate cancer susceptibility in Asian,Caucasian,and all populations.In conclusion,the T allele of the HIF1α1772C/T gene polymorphism was related to prostate cancer risk in the overall populations.

Extracellular vesicles from hypoxia-preconditioned mesenchymal stem cells alleviates myocardial injury by targeting thioredoxininteracting protein-mediated hypoxia-inducible factor-1αpathway

BACKGROUND Extracellular vesicles(EVs)derived from hypoxia-preconditioned(HP)mesenchymal stem cells(MSCs)have better cardioprotective effects against myocardial infarction(MI)in the early stage than EVs isolated from normoxic(NC)-MSCs.However,the cardioprotective mechanisms of HP-EVs are not fully understood.AIM To explore the cardioprotective mechanism of EVs derived from HP MSCs.METHODS We evaluated the cardioprotective effects of HP-EVs or NC-EVs from mouse adipose-derived MSCs(ADSCs)following hypoxia in vitro or MI in vivo,in order to improve the survival of cardiomyocytes(CMs)and restore cardiac function.The degree of CM apoptosis in each group was assessed by the terminal deoxynucleotidyl transferase dUTP nick end-labeling and Annexin V/PI assays.MicroRNA(miRNA)sequencing was used to investigate the functional RNA diversity between HP-EVs and NC-EVs from mouse ADSCs.The molecular mechanism of EVs in mediating thioredoxin-interacting protein(TXNIP)was verified by the dual-luciferase reporter assay.Co-immunoprecipitation,western blotting,and immunofluorescence were performed to determine if TXNIP is involved in hypoxia-inducible factor-1 alpha(HIF-1α)ubiquitination and degradation via the chromosomal region maintenance-1(CRM-1)-dependent nuclear transport pathway.RESULTS HP-EVs derived from MSCs reduced both infarct size(necrosis area)and apoptotic degree to a greater extent than NC-EVs from CMs subjected to hypoxia in vitro and mice with MI in vivo.Sequencing of EV-associated miRNAs showed the upregulation of 10 miRNAs predicted to bind TXNIP,an oxidative stress-associated protein.We showed miRNA224-5p,the most upregulated miRNA in HP-EVs,directly combined the 3’untranslated region of TXNIP and demonstrated its critical protective role against hypoxia-mediated CM injury.Our results demonstrated that MI triggered TXNIP-mediated HIF-1αubiquitination and degradation in the CRM-1-mediated nuclear transport pathway in CMs,which led to aggravated injury and hypoxia tolerance in CMs in the early stage of MI.CONCLUSION The anti-apoptotic effects of HP-EVs in alleviating MI and the hypoxic conditions of CMs until reperfusion therapy may partly result from EV miR-224-5p targeting TXNIP.

Expression of Hypoxia-inducible Factor-1α in Liver Tumors after Transcatheter Arterial Embolization in an Animal Model

To examine the effect of transcatheter arterial embolization （TAE） of liver tumors on hypoxia-inducible factor-1α （HIF-1α） expression in the residual viable tumor, a total of 30 New Zealand White rabbits implanted with VX2 liver tumor were divided into 2 groups. TAE-treated group animals （n=15） were subjected to TAE with 150–250 μm polyvinyl alcohol particles. Control group animals （n=15） underwent sham embolization with distilled water. Six hours, 3 days or 7 days after TAE, the animals were sacrificed, and samples of tumor and adjacent normal liver tissue were harvested. Expression of HIF-1α protein was examined immunohistochemically. Real-time PCR was performed to examine the HIF-1α mRNA levels. Our results showed that HIF-1α protein was expressed in the VX2 tumors but not in the adjacent normal liver tissue. The HIF-1α-positive tumor cells were located predominantly at the periphery of necrotic tumor regions. The mean levels of HIF-1α protein were significantly higher in TAE-treated tumors than those in control tumors （P=0.002）. Among the three sacrificing time points, the difference in increase in HIF-1α protein was significant between the two groups at the sacrificing time point of 6 h and 3 days after TAE （P=0.020, P=0.031, respectively）, whereas no significant increase was noted 7 days after TAE （P=0.502）. In contrast, although HIF-1α mRNA was expressed in TAE-treated and control VX2 tumors, there existed no significant difference in the HIF-1α mRNA level between the two groups （P=0.372）. It is concluded that TAE of liver tumors increases the expression of HIF-1α at protein level in the residual viable tumor, which could be attributed to hypoxia generated by the procedure.

Hypoxia-inducible factor-1a restricts the anabolic actions of parathyroid hormone

The hypoxia inducible factors （Hifs） are evolutionarily conserved transcriptional factors that control homeostatic responses to low oxygen. In developing bone, Hif-1 generated signals induce angiogenesis necessary for osteoblast specification, but in mature bone, loss of Hif-1 in osteoblasts resulted in a more rapid accumulation of bone. These findings suggested that Hif-1 exerts distinct developmental functions and acts as a negative regulator of bone formation. To investigate the function of Hif-1a in osteoanabolic signaling, we assessed the effect of Hif-1a loss-of-function on bone formation in response to intermittent parathyroid hormone （PTH）. Mice lacking Hif-1a in osteoblasts and osteocytes form more bone in response to PTH, likely through a larger increase in osteoblast activity and increased sensitivity to the hormone. Consistent with this effect, exposure of primary mouse osteoblasts to PTH resulted in the rapid induction of Hif-1a protein levels via a post-transcriptional mechanism. The enhanced anabolic response appears to result from the removal of Hif-1a-mediated suppression of β-catenin transcriptional activity. Together, these data indicate that Hif-1a functions in the mature skeleton to restrict osteoanabolic signaling. The availability of pharmacological agents that reduce Hif-1a function suggests the value in further exploration of this pathway to optimize the therapeutic benefits of PTH.

Inhibition of Expression of Hypoxia-inducible Factor-1α mRNA by Nitric Oxide in Hypoxic Pulmonary Hypertension Rats

In order to study the effect of nitric oxide (NO) on the expression of hypoxia inducible factor 1 alpha (HIF 1α) mRNA in hypoxic pulmonary hypertension (HPH) rats, 30 healthy male Wistar rats were randomly divided into normoxic control group, chronic hypoxic group and hypoxia plus L argine (L Arg) group. The animal model of HPH was developed. The mean pulmonary arterial pressure (mPAP) was measured by inserting a microcatheter into the pulmonary artery. The HIF 1α mRNA expression levels were detected by in situ hybridization (ISH) and semiquantitative RT PCR. It was found that after 14 days hypoxia, the mPAP in normoxic control group (17.6±2 7 mmHg,1 mmHg=0 133 kPa) was significantly lower than that in chronic hypoxic group(35.8±6.1 mmHg, t =0.2918, P <0.05) and mPAP in chronic hypoxic group was higher than that in hypoxia plus L argine group(24.4±3.8 mmHg, t =0.2563, P <0.05). ISH showed that the expression of HIF 1α mRNA in the intraacinar pulmonary arteriolae (IAPA) in normoxic control group (0.1076±0.0205) was markedly weaker than that in chronic hypoxic group (0.3317±0.0683, t =3.125, P <0.05) and that in chronic hypoxic group was stronger than that in hypoxia plus L argine group (0.1928±0.0381, t =2.844, P <0.05). RT PCR showed that the content of HIF 1α mRNA in chronic hypoxic group (2.5395±0.6449) was 2.16 times and 1.75 times higher than that in normoxic control group (1.1781±0.3628) and hypoxia plus L argine group (1.4511±0.3981), respectively. It is concluded that NO can reduce the mPAP by the inhibition of the expression of HIF 1α mRNA, which may be one of the mechanisms through which NO affects the pathogenesis of HPH.

Clinicopathological features of hypoxia-inducible factor-1α and vascular endothelial growth factor expression in patients with lung cancer

Objective The aim of the study was to investigate the clinicopathological characteristics of hypoxiainducible factor-1α(HIF-1α) and vascular endothelial growth factor(VEGF) expression in patients with lung cancer.Methods Cancerous and noncancerous tissues were collected post-operation from 115 patients with lung cancers by the self-control method. Total RNA was extracted from the lung tissues. The status of tissue HIF-1α expression and intercellular distribution was observed by immunochemistry using a tissue microarray. The expression levels of circulating HIF-1α and VEGF were detected by enzyme-linked immunosorbent assay(ELISA).Results The expression of serum HIF-1α [(138.3 ± 28.8) μg/L] in the group of patients with lung cancer was significantly higher(P < 0.01) than that in the group of patients with pneumonia [(58.8 ± 14.5) μg/L] and the control group of patients ((24.1 ± 3.3) μg/L)There was a strong positive correlation of serum HIF-1α levels(r = 0.937, P < 0.01) with serum VEGF levels. The specific concentration of total RNA [(1.52 ± 1.14) μg/mg wet lung tissues] in the cancerous tissues was significantly higher(t = 8.494, P < 0.001) than that in the noncancerous tissues ((0.58 ± 0.33) μg/mg)The clinicopathological features of HIF-1α expression in lung cancer tissues revealed a significant relationship between positive HIF-1α expression and patient sex(χ~2 = 4.494, P = 0.034), tumor size(χ~2 = 4.679, P = 0.031), differentiation degree(χ~2= 8.846, P = 0.012), and presence of lymphatic node metastasis(χ~2= 6.604, P = 0.037).Conclusion Abnormal HIF-1α expression in lung cancer is closely related with nucleic acid metabolism and angiogenesis, and it may be helpful in the diagnosis and identification of lung cancer.

Effect of hypoxia-inducible factor-1α on proliferation and invasion of prostate cancer PC-3 cell in hypoxic situation

Objective We transfected recombinant expression plasmid of pcDNA3. 1-HIF-1α into prostate cancer cells, to research effect of HIF-1α on proliferation of prostate cancer cell PC-3. Methods We selected a stable expression cell line with G418 we selected by transfection