Overexpression Of Hypoxia-inducible Factor-1 Alpha Research Articles

HIF1A overexpression caused by etomidate activates PGK1-induced oxidative stress in postoperative cognitive dysfunction

Etomidate (ETO), a hypnotic agent used for anesthesia induction, has been shown to induce long-lasting cognitive deficits. In the present study, we investigated whether ETO could activate the HIF1A/PGK1 pathway to antagonize oxidative damage in mice with postoperative cognitive dysfunction (POCD). A mouse model of ETO-mediated POCD was established, and pathological changes, apoptosis, and inflammatory factors in mouse hippocampal tissues were analyzed by HE staining, TUNEL assay, and ELISA. ETO was revealed to cause cognitive dysfunction in mice. Integrated database mining was conducted to screen out transcription factors that are both related to ETO and POCD. Hypoxia-inducible factor 1-alpha (HIF1A) was overexpressed in mice with POCD, and downregulation of HIF1A alleviated cognitive dysfunction in mice. HIF1A downregulation inhibited the transcription of phosphoglycerate kinase 1 (PGK1). Overexpression of PGK1 abated the alleviating effects of HIF1A knockdown on oxidative stress in mice with POCD. In addition, HIF1A activation of PGK1 induced oxidative stress and apoptosis in HT-22 cells while inhibiting cell viability. Taken together, we demonstrated that HIF1A activation of PGK1 induced oxidative stress in ETO-mediated POCD.

Exogenous Ang-(1-7) inhibits autophagy via HIF-1α/THBS1/BECN1 axis to alleviate chronic intermittent hypoxia-enhanced airway remodelling of asthma

Obstructive sleep apnoea (OSA)-induced chronic intermittent hypoxia (CIH) has been considered a risk factor for severe asthma. Airway remodelling, which could be modulated by autophagy, plays a key role in severe asthma. However, the extent of autophagy’s involvement in CIH-potentiated airway remodelling remains largely unexplored. Furthermore, we had found that angiotensin-(1-7) [Ang-(1-7)] has therapeutic effects on airway remodelling in asthma, but the underlying mechanism is either unclear. This study aimed to explore how CIH aggravates asthma and mechanism of protective effects of Ang-(1-7) on airway remodelling, with a focus on autophagy. We observed that CIH promoted epithelial-to-mesenchymal transition (EMT), indicated by elevated EMT and fibrotic markers such as Snail and Collagen IV, both in vitro and in vivo. CIH intensified cell autophagy, evident from increased LC3B expression and reduced p62 levels. Ang-(1-7) reversed the CIH-enhanced expression of Snail, Collagen IV, and LC3B. To explore how CIH enhanced autophagy in cellular and animal model of asthma, overexpression of hypoxia-inducible factor 1-alpha (HIF-1α) and Thrombospondin 1 (THBS1) were identified in CIH-exposure mice lung compared with normal mice lung tissues from the GEO database. Finally, through chromatin immunoprecipitation and immunoprecipitation assays, we verified that Ang-(1-7) inhibits CIH-induced binding of HIF-1α to the promoter of THBS1, and also disrupts the protein-protein interaction between THBS1 and the autophagy-associated protein Beclin 1 (BECN1), ultimately leading to autophagy inhibition. Our findings suggest that exogenous Ang-(1-7) can inhibit autophagy via HIF-1α/THBS1/BECN1 axis, thereby alleviating CIH-enhanced airway remodelling in asthma. These findings imply the potential therapeutic effect of Ang-(1-7) in asthma with OSA.

Abstract 3960: Therapeutic targeting of HIF-1 alpha induced CD73 expression in experimental esophageal adenocarcinoma

Abstract Introduction: Esophageal adenocarcinoma (EAC) is one of the most aggressive human cancers with poor prognosis, and the overall 5-year survival rate is less than 20 percent. Prognosis for EAC remains poor even with modern combination therapies due to high resistance to chemotherapy. Therefore, new therapeutic approaches for EAC treatment improvements are urgently needed. Hypoxia or insufficient tissue oxygenation contributes to cancer aggressiveness and poor clinical prognosis. Overexpression of hypoxia-inducible factor 1-alpha (HIF-1 alpha) and immunosuppressive CD73, an ecto-5’-nucleotidase enzyme in cancer can give rise to tumor progression with drug resistance. CD73 has never been proposed as a therapeutic target in EAC and its relationship with hypoxia or HIF-1 alpha has not also been investigated in EAC. In this study, we therefore investigated the therapeutic targeting of HIF-1 alpha and CD73 by acriflavine in experimental EAC. Methods: Hypoxia in EAC cells were induced by 3D culture and hypoxic exposure. NanoCulture® plates and dishes were used for 3D cultures. For hypoxic exposure, cells were placed in a sealed modular incubator chamber flushed with a gas mixture containing 1% O2, 5% CO2 and 94% N2. Hypoxic status was detected by adding hypoxia probe LOX-1 and fluorescent microscopy. Nanoparticle albumin-bound paclitaxel (NPT) was used as chemotherapeutic agent, whereas acriflavine was used as hypoxia-targeting agent. In vitro cell growth was detected by WST-1 and Cell Titer-Glo (CTG) luminescent assays, in vivo tumor growth was detected by measuring subcutaneous xenografts, apoptosis was detected by cleaved caspase 3/PARP expressions and hypoxia-targeting was detected by HIF-1 alpha/CD73 expressions. Results: We observed overexpression of both HIF-1 alpha and CD73 in 3D culture and hypoxic exposure of EAC cells. Interestingly acriflavine treatment drastically inhibited both HIF-1 alpha and CD73 expression in EAC 3D culture and hypoxic exposure. 3D culture was more resistant to antiproliferative effect of chemotherapeutic agent NPT over 2D monolayer culture. Contrary to that, hypoxia-targeting agent acriflavine showed stronger antiproliferative effects in 3D culture than in 2D culture. We also observed hypoxia inside the 3D culture spheroids. In addition, acriflavine showed significant in vivo antitumor efficacy both as monotherapy and in combination with NPT. In subcutaneous xenografts using OE19 EAC cells, acriflavine monotherapy exhibited a significant decrease in relative tumor volume to 55.02% compared to control (p=0.04) and addition of NPT with acriflavine also showed a significant enhancement effect of tumor regression as tumor size decreased to 32.70% compared to control (p=0.002). Conclusion: These results support the potential of acriflavine as HIF-1 alpha and CD73 targeting and its combination with chemotherapy NPT as an effective option for EAC therapy. Citation Format: Md Sazzad Hassan, Aktar Ali, Saisantosh Ponna, Dimitri Scofield, Niranjan Awasthi, Mark Jantz, Urs von Holzen. Therapeutic targeting of HIF-1 alpha induced CD73 expression in experimental esophageal adenocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3960.

Hypoxia-responsive nanocarriers for chemotherapy sensitization via dual-mode inhibition of hypoxia-inducible factor-1 alpha

The overexpression of hypoxia-inducible factor-1 alpha (HIF-1α) in solid tumor compromises the potency of chemotherapy under hypoxia. The high level of HIF-1α arises from the stabilization effect of reduced nicotinamideadeninedinucleotide(phosphate) NAD(P)H: quinone oxidoreductase 1 (NQO1). It was postulated that the inhibition of NQO1 could degrade HIF-1α and sensitize hypoxic cancer cells to antineoplastic agents. In the current work, we report hypoxia-responsive polymer micelles, i.e. methoxyl poly(ethylene glycol)-co-poly(aspartate-nitroimidazole) orchestrate with a NQO1 inhibitor (dicoumarol) to sensitize the ovarian cancer cell line (SKOV3) to a model anticancer agent (sorafenib) at low oxygen conditions. Both cargos were physically encapsulated in the nanoscale micelles. The placebo micelles transiently induced the depletion of reduced nicotinamideadeninedinucleotidephosphate (NADPH) as well as glutathione and thioredoxin under hypoxia, which further inactivated NQO1 because NADPH was the cofactor of NQO1. As a consequence, the expression of HIF-1α was repressed due to the dual action of dicoumarol and polymer. The degradation of HIF-1α significantly increased the vulnerability of SKOV3 cells to sorafenib-induced apoptosis, as indicated by the enhancement of cytotoxicity, and increase of caspase 3 and cytochrome C. The current work opens new avenues of addressing hypoxia-induced drug resistance in chemotherapy.

XBP1 Regulates the Transcription of HIF-1a in BALB/c Mice with Chronic Rhinosinusitis without Polyps.

X-box binding protein 1 (XBP1) is a transcription factor that recognizes the CRE-like element in enhancers of human T-cell leukemia virus and MHC class II gene and induces their transcription. This study was performed to characterize the function of XBP1, which was identified to be a differentially expressed gene via GEO database, in chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP). XBP1 expression was significantly elevated in both CRSsNP patients and mice who were accompanied with mucosal thickening, goblet cell hyperplasia and chemosis, glandular hyperplasia, and dense infiltration of inflammatory cells. Silencing of XBP1 suppressed the development of CRSsNP in mice. Mechanistically, knockdown of XBP1 downregulated the expression of hypoxia-inducible factor 1-alpha (HIF-1a), and overexpression of XBP1 led to the opposite result. Silencing of HIF-1a inhibited β-catenin expression and impaired the Wnt/β-catenin pathway. Further overexpression of HIF-1a in XBP1-silenced CRSsNP mice exacerbated pathological changes in mouse nasal mucosal tissues, promoted inflammation, and activated the Wnt/β-catenin pathway. Taken together, overexpression of XBP1 may be associated with increased expression of HIF-1a and possibly contribute to the Wnt/β-catenin pathway activation and the development of CRSsNP.

Knockdown of hypoxia-inducible factor 1-alpha (HIF1α) interferes with angiopoietin-like protein 2 (ANGPTL2) to attenuate high glucose-triggered hypoxia/reoxygenation injury in cardiomyocytes

ABSTRACT To investigate the role of hypoxia-inducible factor 1-alpha (HIF1A) in hypoxia/reoxygenation (H/R) injury of cardiomyocytes induced by high glucose (HG). The in vitro model of coronary heart disease with diabetes was that H9c2 cells were stimulated by H/R and HG. Quantitative reverse transcription PCR (RT-qPCR) and Western blot analysis were used to detect the expression of HIF1A and angiopoietin-like protein 2 (ANGPTL2) in H9c2 cells. Cell viability and apoptosis were, respectively, estimated by Cell Counting Kit 8 (CCK-8) and TUNEL assays. Lactate dehydrogenase (LDH) activity, inflammation and oxidative stress were in turn detected by their commercial assay kits. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay were used to confirm the association between HIF1A and ANGPTL2 promoter. The expression of nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway-related proteins and apoptosis-related proteins were also detected by Western blot analysis. As a result, ANGPTL2 expression was upregulated in H9c2 cells induced by HG or/and H/R. ANGPTL2 positively modulated HIF1A expression in H9c2 cells. HG or/and H/R suppressed the cell viability and promoted apoptosis, inflammatory response and oxidative stress levels in H9c2 cells. However, the knockdown of ANGPTL2 could reverse the above phenomena in H/R-stimulated-H9c2 cells through activation of Nrf2/HO-1 pathway. HIF1A transcriptionally activated ANGPTL2 expression. The effect of knockdown of ANGPTL2 on H/R triggered-H9c2 cells was weakened by HIF1A overexpression. In conclusion, knockdown of HIF1A downregulated ANGPTL2 to alleviate H/R injury in HG-induced H9c2 cells by activating the Nrf2/HO-1 pathway.

Hsa_circ_0019054 up-regulates HIF1A through sequestering miR-340-5p to promote the tumorigenesis of intrahepatic cholangiocarcinoma.

Circular RNAs (circRNAs) have been uncovered to play an important regulatory function in the tumorigenesis of intrahepatic cholangiocarcinoma (ICC). Hsa_circ_0,019,054 was found to be increased in ICC. Here, we aimed to explore the action and mechanism of hsa_circ_0,019,054 in ICC carcinogenesis. Quantitative real-time PCR (qRT-PCR) and western blotting were used to detect the levels of genes and proteins. The functional experiments were performed using in vitro 5-ethynyl-2'-deoxyuridine (EdU) assay, cell counting Kit-8 (CCK-8) assay, flow cytometry, and in vivo murine xenograft model. The glycolysis was analyzed by detecting glucose uptake and lactate level. The binding between miR-340-5p and hsa_circ_0,019,054 or HIF1A (Hypoxia-inducible factor 1-alpha) was validated using pull-down, dual-luciferase reporter and RNA immunoprecipitation assays. Hsa_circ_0,019,054 expression was higher in ICC tissues and cells. Functionally, hsa_circ_0,019,054 silencing could suppress ICC cell proliferation and glycolysis active, as well as induce apoptosis. Mechanistically, hsa_circ_0,019,054 was demonstrated to act as a sponge for miR-340-5p, which directly targeted HIF1A. Hsa_circ_0,019,054/miR-340-5p/HIF1A formed a feedback loop. HIF1A was up-regulated, while miR-340-5p was decreased in ICC tissues and cells. MiR-340-5p re-expression attenuated ICC cell growth. Besides that, rescue experiments suggested that HIF1A overexpression or miR-340-5p knockdown reversed the anti-proliferation and glycolysis arrest effects mediated by hsa_circ_0,019,054 silencing. Importantly, hsa_circ_0,019,054 silencing also impeded the growth of ICC in nude mice. Hsa_circ_0,019,054 deficiency could attenuate the proliferation and glycolysis of ICC cells via miR-340-5p/HIF1A axis.

Evaluation of pro-apoptotic potential of taxifolin against liver cancer.

Liver cancer is the second most common cause of cancer-induced deaths worldwide. Liver cirrhosis and cancer are a consequence of the abnormal angio-architecture formation of liver and formation of new blood vessels. This angiogenesis is driven by overexpression of hypoxia-inducible factor 1-alpha (Hif1-α) and vascular endothelial growth factor (VEGF). Apart from this, protein kinase B (Akt) is also impaired in liver cancer. Despite the advancement in conventional treatments, liver cancer remains largely incurable. Nowadays, the use of naturally occurring anticancer agents particularly flavonoids is subject to more attention due to their enhanced physicochemical properties. Therefore, this study underlines the use of a natural anticancer agent taxifolin in the treatment of liver cancer using hepatocellular carcinoma cell line HepG2 and Huh7. The aim of our study is to devise a natural and efficient solution for the disease prevalent in Pakistan. The study involved the assessment of binding of ligand taxifolin using molecular docking. The binding of taxifolin with the proteins (Hif1-α, VEGF and Akt) was calculated by docking using Vina and Chimera. Further evaluation was performed by cell viability assay (MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay), colony formation assay, cell migration assay, DNA ladder assay and flow cytometry. To see whether taxifolin directly affected expression levels, analysis of gene expression of Hif1-α, VEGF and Akt was performed using real-time polymerase chain reaction (qPCR) and western blotting. In silico docking experiments revealed that these proteins showed favorable docking scores with taxifolin. Treatment with taxifolin resulted in the inhibition of the liver cancer growth and migration, and induced apoptosis in HepG2 and Huh7 cell lines at an inhibitory concentration (IC50) value of 0.15 µM and 0.22 µM, respectively. The expression of HIF1-α, VEGF and Akt was significantly reduced in a dose- dependent manner. The inhibitory effect of taxifolin on hepatic cells suggested its chemopreventive and therapeutic potential. The studied compound taxifolin exhibited pronounced pro-apoptotic and hepatoprotective potential. Our study has confirmed the pro-apoptotic potential of taxifolin in liver cancer cell lines and will pave a way to the use of taxifolin as a chemotherapeutic agent after its further validation on the animal models and humans based epidemiological studies.

ANTI‐NEOPLASTIC EFFECTS OF METFORMIN AGAINST RENAL CLEAR CELL CARCINOMA

Background and ObjectivesRenal clear cell carcinoma (RCCC) is the most common and lethal form of urological cancer diagnosed globally. Mutation of Von‐Hippel Lindau (VHL) tumor suppresser gene and the resultant overexpression of hypoxia‐inducible factor‐1 alpha (HIF‐1α) protein promotes cell proliferation, angiogenesis and epithelial‐mesenchymal transition (EMT) and leads to RCCC progression and metastasis. Moreover, cancer drug resistance continues to be a major impediment to the treatment of RCCC. Metformin, an activator of AMP‐activated kinase (AMPK), is primarily prescribed for the management of type‐2 diabetes; nonetheless, emerging studies suggest that metformin exerts anti‐neoplastic effects in various types of cancers. Thus, the objectives of this study were to investigate metformin's antineoplastic effects and the signaling pathways modulated by metformin in RCCC using a human renal carcinoma cell line ‐ Caki‐2.MethodsCaki‐2 cells, which lack functional VHL, were treated with metformin (ranging from 1 to 50 mM) for 48 h and assessed for cell viability (using Alamar blue assay), cell cycle progression (using Tali cell cycle kit), cell migration (using in vitro scratch migration technique at 6 and 24 h). Western blotting analysis was performed to assess the effects of metformin on various signaling pathways such as AMPK, mammalian target of rapamycin (mTOR), AKT, HIF‐1α, autophagy (LC3II) pathway and epithelial‐mesenchymal transition or EMT marker (α‐SMA).ResultsFollowing 48 h metformin treatment, a significant and dose‐dependent decrease in cell viability were observed, i.e., 81% in 2 mM, 69% in 5 mM, 60% in 10 mM, 47% in 20 mM and 34% in 50 mM in metformin treated cells compared to control (set as 100%). Similarly, cell cycle analysis revealed a significant and dose‐dependent cell cycle arrest at G0/G1 phase in metformin treated cells compared to control. A prominent decrease in the migration of Caki‐2 cells was noted after 6 and 24 h of metformin treatment (5 mM and 10 mM) compared to control. Western blot analysis revealed a dose‐dependent increase in the levels of phosphorylated (active) AMPK i.e., 115% in 2 mM, 148% in 5 mM and 172% in 10 mM in metformin treated cells in comparison to control (set at 100%). In contrast, a significant decrease in the levels of phosphorylated (active) forms of mTOR (49% in 2 mM, 34% in 5 mM and 20% in 10 mM) and AKT (84% in 5 mM and 66 % in 10 mM) were noted in metformin treated Caki‐2 cells. Moreover, marked downregulation of HIF‐1α expression (62%) and reductions in the levels of EMT marker ‐ α‐SMA (30%) and autophagy marker ‐ LC3II protein (67%) were observed in Caki‐2 cells treated with metformin at 10 mM.ConclusionOur findings indicate that metformin exerts potent anti‐neoplastic and anti‐metastatic effects in RCCC through concerted activation of AMPK pathway and repression of AKT, mTOR, HIF‐1α, LC3II protein and EMT signaling pathways. The modulation of the aforementioned signaling pathways might contribute to the cell cycle arrest at the G0/G1 phase and reductions in cell migration. Together, our study unveils the therapeutic potential of metformin to inhibit the progression of RCCC in vitro.Support or Funding InformationThis study was supported by the intramural research grants from Drake University and Qatar University.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Overexpression of hypoxia-inducible factor 1 alpha improves immunomodulation by dental mesenchymal stem cells

BackgroundHuman dental mesenchymal stem cells (MSCs) are considered as highly accessible and attractive MSCs for use in regenerative medicine, yet some of their features are not as well characterized as other MSCs. Hypoxia-preconditioning and hypoxia-inducible factor 1 (HIF-1) alpha overexpression significantly improves MSC therapeutics, but the mechanisms involved are not fully understood. In the present study, we characterize immunomodulatory properties of dental MSCs and determine changes in their ability to modulate adaptive and innate immune populations after HIF-1 alpha overexpression.MethodsHuman dental MSCs were stably transduced with green fluorescent protein (GFP-MSCs) or GFP-HIF-1 alpha lentivirus vectors (HIF-MSCs). A hypoxic-like metabolic profile was confirmed by mitochondrial and glycolysis stress test. Capacity of HIF-MSCs to modulate T-cell activation, dendritic cell differentiation, monocyte migration, and polarizations towards macrophages and natural killer (NK) cell lytic activity was assessed by a number of functional assays in co-cultures. The expression of relevant factors were determined by polymerase chain reaction (PCR) analysis and enzyme-linked immunosorbent assay (ELISA).ResultsWhile HIF-1 alpha overexpression did not modify the inhibition of T-cell activation by MSCs, HIF-MSCs impaired dendritic cell differentiation more efficiently. In addition, HIF-MSCs showed a tendency to induce higher attraction of monocytes, which differentiate into suppressor macrophages, and exhibited enhanced resistance to NK cell-mediated lysis, which supports the improved therapeutic capacity of HIF-MSCs. HIF-MSCs also displayed a pro-angiogenic profile characterized by increased expression of CXCL12/SDF1 and CCL5/RANTES and complete loss of CXCL10/IP10 transcription.ConclusionsImmunomodulation and expression of trophic factors by dental MSCs make them perfect candidates for cell therapy. Overexpression of HIF-1 alpha enhances these features and increases their resistance to allogenic NK cell lysis and, hence, their potential in vivo lifespan. Our results further support the use of HIF-1 alpha-expressing dental MSCs for cell therapy in tissue injury and immune disorders.

HIF1A overexpression using cell-penetrating DNA-binding protein induces angiogenesis in vitro and in vivo

Hypoxia-inducible factor-1 alpha (HIF1A) is an important transcription factor for angiogenesis. Recent studies have used the protein transduction domain (PTD) to deliver genes, but the PTD has not been used to induce the expression of HIF1A. This study aimed at using a novel PTD (Hph-1-GAL4; ARVRRRGPRR) to overexpress the HIF1A and identify the effects on angiogenesis in vitro and in vivo. Overexpression of HIF1A was induced using Hph-1-GAL4 in human umbilical vein/vascular endothelium cells (HUVEC). The expression levels of genes were analyzed by the quantitative real-time polymerase chain reaction (qPCR) after 2 and 4days, respectively. An in vitro tube formation was performed using Diff-Quik staining. HIF1A and Hph-1-GAL4 were injected subcutaneously into the ventral area of each 5-week-old mouse. All of the plugs were retrieved after 1week, and the gene expression levels were evaluated by qPCR. Each Matrigel plug was evaluated using the hemoglobin assay and hematoxylin and eosin (HE) staining. The expression levels of HIF1A and HIF1A target genes were significantly higher in HIF1A-transfected HUVEC than in control HUVEC in vitro. In the in vivo Matrigel plug assay, the amount of hemoglobin was significantly higher in the HIF1A-treatment group than in the PBS-treatment group. Blood vessels were identified in the HIF1A-treatment group. The expression levels of HIF1A, vascular endothelial growth factor (Vegf), and Cd31 were significantly higher in the HIF1A-treatment group than in the PBS-treatment group. These findings suggest that using Hph-1-G4D to overexpress HIF1A might be useful for transferring genes and regenerating tissues.

Overexpression of hypoxia-inducible factor-1 alpha improves vasculogenesis-related functions of endothelial progenitor cells

Postnatal vasculogenesis is mediated by mobilization of endothelial progenitor cells (EPCs) from bone marrow and homing to ischemic tissues. This feature emphasizes this cell type for cell-based therapies aiming at the improvement of neovascularization in tissue engineering applications and regenerative medicine. In animal models, it was demonstrated that implantation of EPCs from cord blood (cbEPCs) led to the formation of a complex functional neovasculature, whereas EPCs isolated from adult peripheral blood (pbEPCs) showed a limited vasculogenic potential, which may be attributed to age-related dysfunction. Recently, it was demonstrated that activation of hypoxia-inducible factor-1α (Hif-1α) improves cell functions of progenitor cells of mesenchymal and endothelial origin. Thus, we hypothesized that overexpression of Hif-1α may improve the vasculogenesis-related phenotype of pbEPCs. In the present study, we overexpressed Hif-1α in pbEPCs and cbEPCs by using recombinant adenoviruses and investigated effects on stem cell- and vasculogenesis-related cell parameters. Overexpression of Hif-1α enhanced proliferation, invasion, cell survival and in vitro capillary sprout formation of both EPC populations. Migration was increased in cbEPCs upon Hif-1α overexpression, but not in pbEPCs. Cellular senescence was decreased in pbEPCs, while remained in cbEPCs, which showed, as expected, intrinsically a dramatically lower senescent phenotype in relation to pbEPCs. Similarly, the colony-formation capacity was much higher in cbEPCs in comparison to pbEPCs and was further increased by Hif-1α overexpression, whereas Hif-1α transduction exerted no significant influence on colony formation of pbEPCs. In summary, our experiments illustrated multifarious effects of Hif-1α overexpression on stem cell and vasculogenic parameters. Therefore, Hif-1α overexpression may represent a therapeutic option to improve cellular functions of adult as well as postnatal EPCs.

HIF1A expression in localized prostate cancer treated with dose escalation radiation therapy.

To analyze the expression of hypoxia inducible factor 1 alpha (HIF1A) and its correlation with clinical outcome in men with localized prostate cancer (PC) treated with dose escalation radiotherapy (RT) and androgen deprivation (AD). Between 1996 and 2004, 129 PC patients who had diagnostic biopsies pre-treatment and 24-36 months following RT were enrolled in this study. Median follow-up was 129 months. Suitable archival diagnostic tissue was obtained from 86 patients. Correlation analysis was done to assess association between HIF1A expression and clinical outcome. HIF1A expression was observed in 25/86 (29%) of diagnostic biopsies, and in 5/14 (36%) of post-RT biopsies. No significant association was noted between HIF1A expression and clinical and treatment parameters. We also failed to show a significant correlation between HIF1A overexpression and outcome. A borderline significant relationship was observed between expression of HIF1A and overall survival (OS) (HR 0.03, p=0.08). To our knowledge this is the first study assessing the pattern of change of HIF1A staining in biopsies of patients prior and following treatment. While we did not find significant variations in the expression of HIF1A following radio-hormone therapy, a high HIF1A expression was unexpectedly associated with a borderline improved OS.

Over-expression of hypoxia-inducible factor-1 alpha in vitro protects the cardiac fibroblasts from hypoxia-induced apoptosis

A great number of studies indicate that cardiac fibroblasts are essential for maintaining the structure and function of heart. Hypoxia-inducible factor-1 alpha (HIF-1α) is a central transcriptional regulator of hypoxic response. The present study examined whether over-expression of HIF-1α could prevent hypoxia-induced injury in neonatal rat cardiac fibroblasts and, if so, its possible molecular targets. Western blotting was used to detect protein level. MTT, electron microscopy, TUNEL staining and confocal microscopy were used to identify cell viability, cell apoptosis and intracellular calcium ([Ca]i) in cardiac fibroblasts, respectively. When cardiac fibroblasts were exposed to hypoxia, HIF-1α protein in nuclei was transiently accumulated at 1 h, and then gradually degraded within 24 h of hypoxia exposure. Over-expression of HIF-1α enhanced nucleus expression of HIF-1α in cardiac fibroblasts, and significantly abolished the decrease of cell viability and cell apoptosis caused by 24-h hypoxia. Accordingly, hypoxia-induced Bax up-regulation, Bcl-2 down-regulation, caspase-3 activation and overload of [Ca]i in cardiac fibroblasts were reversed by HIF-1α over-expression, but were promoted by 30 μmol/l SC205346, a specific HIF-1α blocker. Our results indicate that HIF-1α may act as a protective factor in the apoptotic process of cardiac fibroblasts and represent a potential therapeutic target for heart remodeling after hypoxia injury.

124I-cG250 PET scan for early detection of response to sunitinib in patients (Pts) with metastatic clear cell renal cell carcinoma (MccRCC).

362 Background: Mutation and/or methylation of the von Hippel-Lindau gene leading to overexpression of hypoxia-inducible factor-1 alpha (HIF1α) has been implicated as a driving event in the pathogenesis of ccRCC. Downstream effectors of HIF1α such as VEGF have become key targets of novel therapies for MccRCC (eg, sunitinib (S)). Carbonic anhydrase-IX (CAIX) transcription is also regulated by HIF1α and is overexpressed in ~95% of ccRCC. Linkage of cG250 (Girentuximab), a chimeric antibody to CAIX, to radioactive iodine (124I), has resulted in a radiotracer specific for ccRCC; 124I-cG250 (124I-Girentuximab) PET/CT demonstrated a sensitivity of 86% and a specificity of 87% for detecting primary ccRCC (Uzzo AUA 2010). Since responses to targeted therapies likely occur on a molecular level before they are detectable with standard imaging, we hypothesize that 124I-cG250 PET/CT could allow earlier recognition of response or progression to S than CT in pts with MccRCC. Methods: This is a pilot study of 124I-cG250 PET/CT in 25 pts with MccRCC planned to begin treatment (Tx) with S. 124I-cG250 PET/CT will be assessed for its ability to predict Tx response during (days 25–28) and at completion (days 39-42) of the first cycle of therapy, in comparison to standard CT imaging at routine intervals. PET/CT and CT will each be interpreted by 1 nuclear medicine physician, who will be blinded to the results of the comparator imaging modality, but aware of the clinical history of the pts. Eligibility include age ≥18, ECOG PS < 2, histologically confirmed MccRCC, Tx planned with S, and radiographic evidence of unidimensionally measurable disease with at least one lesion ≥2 cm in diameter on 16-slice multi-detector CT. Key exclusion criteria include uncontrolled/unstable hyperthyroidism or Grave’s Disease, unstable cardiac disease and uncontrolled seizure disorder or history of CVA or TIA within the past 12 months. Results: NA. Conclusions: This is the first clinical trial to prospectively evaluate the use of a histologically specific imaging modality to measure early changes in ccRCC CAIX protein expression as a predictor of response to biologically targeted Tx. Enrollment will commence in November 2011.

Tyrosine kinase receptor inhibitor-targeted combined chemotherapy for metastatic bladder cancer

Overexpression of hypoxia-inducible factor-1 alpha is noted during the invasive and metastatic process of transitional cell carcinoma. It will upregulate vascular endothelial growth factor (VEGF) and drive proliferation, invasiveness, metastasis, and antiapoptotic ability of cancer cells. We proposed that tyrosine kinase receptor inhibitor, sunitinib malate—(Sutent; Pfizer Inc., Taiwan), combined with chemotherapeutic drug may present synergistic cytotoxic enhancement to transitional cell carcinoma cells with subsequent inhibition of their cellular behaviors, including proliferation, invasiveness, and metastatic activity. The contents of VEGF-A in mouse bladder tumor cells (MBT-2) and culture medium were detected by quantification-polymerase chain reaction and Western blot individually. The inhibitory concentrations of various chemotherapeutic drugs, sunitinib, and their combination treatment in MBT-2 were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Microchamber transmembrane migration assay was applied in evaluation of the inhibitory effects of different dosages of sunitinib and combination treatment on tumor cells. The cell cycle and apoptosis were analyzed after combination therapy by flow cytometry. Variation in apoptotic pathway was elucidated by Western blot using specific antibodies with cleaved PARP and caspase-3. Metastatic animal model mimicked by tail vein injection of MBT-2 cells was used to evaluate the treatment efficiency in tumor weight and survival rate. The mRNA and protein level of VEGF-A in MBT-2 cells increased by 70% at 48 hours interval under hypoxia stress condition. In MTT assay, MBT-2 cells had shown the highest sensitivity to epirubicin. Sunitinib combined with epirubicin had shown a synergistic cytotoxic effect to MBT-2 cells. Sunitinib and its combination with epirubicin showed significant inhibition on MBT-2 cells migration in microchambers. G2/M phase arrest and increased subG1 in cell cycle was seen in the epirubicin and sunitinib combination treatment group. The activation of apoptosis pathway was confirmed by increased cleaved caspase-3 and cleaved PARP in MBT-2 cells. In tail vein tumor inoculation C3H mice model, epirubicin alone and sunitinib combination therapy decreased tumor growth in lungs with marginal effect. Sunitinib and epirubicin combination had shown a synergistic cytotoxic effect and inhibited cell migration ability in MBT-2 cells. The combination can induce cell cycle arrest at G2/M phase and increase subG1 cells. Metastatic animal study also showed that sunitinib combined with epirubicin has a marginal effect on inhibition of tumor growth of lungs. The tyrosine kinase receptor inhibitor-targeted combined chemotherapy regimen may provide as a new treatment modality for advanced bladder cancer in the future.

Regulation of Membrane-Type 4 Matrix Metalloproteinase by SLUG Contributes to Hypoxia-Mediated Metastasis

The hypoxic tumor environment has been shown to be critical to cancer metastasis through the promotion of angiogenesis, induction of epithelial-mesenchymal transition (EMT), and acquisition of invasive potential. However, the impact of hypoxia on the expression profile of the proteolytic enzymes involved in invasiveness is relatively unknown. Membrane-type 4 matrix metalloproteinase (MT4-MMP) is a glycosyl-phosphatidyl inositol-anchored protease that has been shown to be overexpressed in human cancers. However, detailed mechanisms regarding the regulation and function of MT4-MMP expression in tumor cells remain unknown. Here, we demonstrate that hypoxia or overexpression of hypoxia-inducible factor-1alpha (HIF-1alpha) induced MT4-MMP expression in human cancer cells. Activation of SLUG, a transcriptional factor regulating the EMT process of human cancers, by HIF-1alpha was critical for the induction of MT4-MMP under hypoxia. SLUG regulated the transcription of MT4-MMP through direct binding to the E-box located in its proximal promoter. Short-interference RNA-mediated knockdown of MT4-MMP attenuated in vitro invasiveness and in vivo pulmonary colonization of tumor cells without affecting cell migratory ability. MT4-MMP promoted invasiveness and pulmonary colonization through modulation of the expression profile of MMPs and angiogenic factors. Finally, coexpression of HIF-1alpha and MT4-MMP in human head and neck cancer was predictive of a worse clinical outcome. These findings establish a novel signaling pathway for hypoxia-mediated metastasis and elucidate the underlying regulatory mechanism and functional significance of MT4-MMP in cancer metastasis.

Increased HIF‐1 alpha immunostaining in psoriasis compared to psoriasiform dermatitides

Expression of hypoxia inducible factor 1 (HIF-1) alpha can be linked to inflammation through reciprocal interactions with several cytokines. This finding is in accordance with the previously noted HIF-1 alpha overexpression in psoriatic lesional keratinocytes. In this study we have employed a carefully selected panel of antibodies and quantitative morphometric analysis to compare HIF-1 alpha immunoreactivity in psoriatic biopsy samples vs. that in samples obtained from psoriasiform dermatitides. We found statistically significant HIF-1 alpha overexpression in psoriasis. Furthermore, we observed a previously unreported preferential localization of immunoreactive keratinocytes in the immediate vicinity of inflamed and elongated papillae. This pattern of immunoreactivity may partially account for the observed increase of HIF-1 alpha immunostaining in psoriasis. Overall, our findings imply that possible novel therapeutic intervention(s) on the HIF-1 alpha pathway may offer another approach in controlling the inflammatory activity of psoriatic lesions.

PX‐478, an inhibitor of hypoxia‐inducible factor‐1α, enhances radiosensitivity of prostate carcinoma cells

Overexpression of hypoxia-inducible factor-1alpha (HIF-1alpha) in human tumors is associated with poor prognosis and poor outcome to radiation therapy. Inhibition of HIF-1alpha is considered as a promising approach in cancer therapy. The purpose of this study was to test the efficacy of a novel HIF-1alpha inhibitor PX-478 as a radiosensitizer under normoxic and hypoxic conditions in vitro. PC3 and DU 145 prostate carcinoma cells were treated with PX-478 for 20 hr, and HIF-1alpha protein level and clonogenic cell survival were determined under normoxia and hypoxia. Effects of PX-478 on cell cycle distribution and phosphorylation of H2AX histone were evaluated. PX-478 decreased HIF-1alpha protein in PC3 and DU 145 cells. PX-478 produced cytotoxicity in both cell lines with enhanced toxicity under hypoxia for DU-145. PX-478 (20 mumol/L) enhanced the radiosensitivity of PC3 cells irradiated under normoxic and hypoxic condition with enhancement factor (EF) 1.4 and 1.56, respectively. The drug was less effective in inhibiting HIF-1alpha and enhancing radiosensitivity of DU 145 cells compared to PC3 cells with EF 1.13 (normoxia) and 1.25 (hypoxia) at 50 mumol/L concentration. PX-478 induced S/G2M arrest in PC3 but not in DU 145 cells. Treatment of PC3 and DU 145 cells with the drug resulted in phosphorylation of H2AX histone and prolongation of gammaH2AX expression in the irradiated cells. PX-478 is now undergoing Phase I clinical trials as an oral agent. Although the precise mechanism of enhancement of radiosensitivity remains to be identified, this study suggests a potential role for PX-478 as a clinical radiation enhancer.

Up-regulation of the hypoxia-inducible factor–1 transcriptional pathway in colorectal carcinomas

The aim of the study was to identify the impact on prognosis of hypoxia-inducible factor-1 genetic program in colorectal carcinomas and to develop an experimental procedure that would allow a reliable quantitative gene expression analysis in formalin-fixed and paraffin-embedded tissue. The expression of hypoxia-inducible factor-1alpha and 13 hypoxia-inducible factor-1 target genes (AMF, CAIX, VEGF, VEGFR1, VEGFR2, HGF, MET, TGFalpha, EGFR, IGF2, MMP2, PLAUR, NIX) was quantified by real-time polymerase chain reaction in 18 colorectal, poorly differentiated neuroendocrine carcinomas and in 60 invasive colorectal carcinomas. Moreover, hypoxia-inducible factor-1alpha protein expression was evaluated by immunohistochemistry. High levels of hypoxia-inducible factor-1alpha were positively associated with poorly differentiated neuroendocrine carcinoma histology (P < .005), poor differentiation (P < .025), presence of necrosis, and presence of microsatellite instability (P < .05). AMF, TGFalpha, IGF2, NIX, VEGF, and VEGFR2 transcripts were significantly higher in the very aggressive poorly differentiated neuroendocrine carcinomas than in exocrine colorectal carcinomas and TGFalpha expression was significantly associated with presence of lymph nodal metastases (P < .05). High levels of TGFalpha and NIX were significantly associated with decreased overall survival (P < .001; P < .01). The multivariate analysis showed that advanced stage, presence of lymph node metastases, and high TGFalpha expression had an independent effect on survival (P < .006; P < .01; P < .0006). Our study suggests an up-regulation of the hypoxia-inducible factor-1 transcriptional pathway in colorectal carcinomas. hypoxia-inducible factor-1alpha overexpression alone, has no impact on the prognosis of colorectal carcinomas likely because the consequences of hypoxia-inducible factor-1alpha expression/stabilization strongly depend on the genetic background of the transformed cells. Mechanisms leading to increased synthesis of hypoxia-inducible factor-1alpha mRNA via autocrine growth factor loops may play a crucial role in invasive growth in this site.