Hypoxia-inducible Factor-1 Protein Expression Research Articles

U-Shape Pillar Strip for 3D Cell-Lumped Organoid Model (3D-COM) Mimicking Lung Cancer Hypoxia Conditions in High-Throughput Screening (HTS).

Hypoxia is a representative tumor characteristic associated with malignant progression in clinical patients. Engineered in vitro models have led to significant advances in cancer research, allowing for the investigation of cells in physiological environments and the study of disease mechanisms and processes with enhanced relevance. In this study, we propose a U-shape pillar strip for a 3D cell-lumped organoid model (3D-COM) to study the effects of hypoxia on lung cancer in a high-throughput manner. We developed a U-pillar strip that facilitates the aggregation of PDCs mixed with an extracellular matrix to make the 3D-COM in 384-plate array form. The response to three hypoxia-activated prodrugs was higher in the 3D-COM than in the 2D culture model. The protein expression of hypoxia-inducible factor 1 alpha (HIF-1α) and HIF-2α, which are markers of hypoxia, was also higher in the 3D-COM than in the 2D culture. The results show that 3D-COM better recapitulated the hypoxic conditions of lung cancer tumors than the 2D culture. Therefore, the U-shape pillar strip for 3D-COM is a good tool to study the effects of hypoxia on lung cancer in a high-throughput manner, which can efficiently develop new drugs targeting hypoxic tumors.

Allantopyrone A interferes with the degradation of hypoxia-inducible factor 1α protein by reducing proteasome activity in human fibrosarcoma HT-1080 cells.

Allantopyrone A is an α-pyrone metabolite that was originally isolated from the endophytic fungus Allantophomopsis lycopodina KS-97. We previously demonstrated that allantopyrone A exhibits anti-cancer, anti-inflammatory, and neuroprotective activities. In the present study, we showed that allantopyrone A up-regulated the protein expression of hypoxia-inducible factor (HIF)-1α in human fibrosarcoma HT-1080 cells. It also up-regulated the mRNA expression of BNIP3 and ENO1, but not other HIF target genes or HIF1A. Allantopyrone A did not inhibit the prolyl hydroxylation of HIF-1α, but enhanced the ubiquitination of cellular proteins. Consistent with this result, chymotrypsin-like and trypsin-like proteasome activities were reduced, but not completely inactivated by allantopyrone A. Allantopyrone A decreased the amount of proteasome catalytic subunits. Therefore, the present results showed that allantopyrone A interfered with the degradation of HIF-1α protein by reducing proteasome activity in human fibrosarcoma HT-1080 cells.

APP Knock-In Mice Produce E22P-Aβ Exhibiting an Alzheimer's Disease-like Phenotype with Dysregulation of Hypoxia-Inducible Factor Expression.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that requires further pathological elucidation to establish effective treatment strategies. We previously showed that amyloid β (Aβ) toxic conformer with a turn at positions 22-23 is essential for forming highly toxic oligomers. In the present study, we evaluated phenotypic changes with aging in AD model AppNL-P-F/NL-P-F (NL-P-F) mice with Swedish mutation (NL), Iberian mutation (F), and mutation (P) overproducing E22P-Aβ, a mimic of toxic conformer utilizing the knock-in technique. Furthermore, the role of the toxic conformer in AD pathology was investigated. NL-P-F mice produced soluble toxic conformers from an early age. They showed impaired synaptic plasticity, glial cell activation, and cognitive decline, followed by the accumulation of Aβ plaques and tau hyperphosphorylation. In addition, the protein expression of hypoxia-inducible factor (HIF)-1α was increased, and gene expression of HIF-3α was decreased in NL-P-F mice. HIF dysregulation due to the production of soluble toxic conformers may be involved in AD pathology in NL-P-F mice. This study could reveal the role of a highly toxic Aβ on AD pathogenesis, thereby contributing to the development of a novel therapeutic strategy targeting the toxic conformer.

Co-Culturing of Osteoblasts and Chondrocytes Upregulates HIF-1 Pathway of Chondrocytes via MAPK Signaling

To study the effect of co-culturing chondrocytes with osteoblasts on hypoxia-inducible factor (HIF)-1 pathway of chondrocytes and its mechanism. Chondrocytes and osteoblasts were separately extracted from the knee joint and skull of newborn mice by trypsin digestion. The co-culturing system of osteoblasts and chondrocytes was constructed by using Transwell inserts to culture the osteoblasts and 6-well plate to culture the chondrocytes. We used qRT-PCR to examine changes in the mRNA expression of HIFs and its target gene pyruvate dehydrogenase kinase 1 ( PDK1) in chondrocytes co-cultured for 24 h. Western blot was used to analyze changes in the protein expression of HIFs and PDK1 and the changes in the activation of mitogen activated protein kinase (MAPK) signaling pathway after the cells were co-cultured for 48 h. Reactive oxygen species (ROS) staining was done to show the changes of ROS production in chondrocytes co-cultured for 48 h. The results of qRT-PCR and Western blot showed upregulated levels of HIF-1α gene and protein expression ( P<0.05) in the chondrocytes after they were co-cultured with osteoblasts. The gene and protein expression levels of PDK1 , the target gene of HIF-1, were also upregulated ( P<0.05). ROS staining showed that co-culturing of chondrocytes with osteoblasts decreased ROS production in chondrocytes. Western blot revealed that extracellular signal-regulated kinase (ERK) 1/2 and p38 signaling of co-cultured chondrocytes were enhanced ( P<0.05). Co-culturing with osteoblasts enhanced the ERK1/2 and p38 signaling of chondrocytes and upregulated the HIF-1 pathway of chondrocytes.

Rehmannia glutinosa polysaccharide increases the expression of erythropoietin and vascular endothelial growth factor in rats with chronic renal failure by activating hypoxia-inducible factor-2α

Background: To investigate the effect of Rehmannia glutinosa polysaccharide (RGP) in rats with chronic renal failure. Materials and Methods: In this study, we established a rat model of adenine-induced chronic renal failure. Hemoglobin (Hb), red blood cells (RBCs), total protein (TP), serum albumin (ALB), blood urea nitrogen (BUN), cystatin C (Cys C), and serum creatinine anhydride (SCA) were detected in the blood samples of rats. Hematoxylin and eosin staining was used to observe the pathological changes. Immunohistochemical was used to detect the protein expression of hypoxia-inducible factor (HIF)-2α, erythropoietin (EPO), and vascular endothelial growth factor (VEGF) and calculate the value of microvessel density (MVD) in renal tissues. M1001 and GPRRP + PT2385 groups were added to further validate the mechanism of RGP. Results: In the case of rats with chronic renal failure, GPRRP and EPO contributed to the repairment of renal tissue. The level of Hb, TP, and ALB, as well as RBC counts was significantly increased, and the renal function indexes, including BUN, SCA, and Cys C, were significantly decreased, and HIF-2α, EPO, VEGF, and MVD were significantly increased. The effects observed in M1001 group was similar to those in GPRRP group, but compared with GPRRP + PT2385 group, the biochemical indicators and renal function indexes were significantly decreased, which means HIF-2α inhibitor antagonized the protective effect of RGP. Conclusion: RGP played an essential role in repairing the renal injury in rats with chronic renal failure. The therapeutic mechanism of action may be related to the activation of HIF-2α, thereby increasing the expression of EPO and VEGF and then reducing renal anemia and renal tissue damage.

Molecular Mechanisms of Hypoxia‐Induced Extracellular Vesicle Release

BackgroundExtracellular vesicles (EVs) are released by many cells and provide a mechanism for intercellular communication in autocrine and paracrine fashion. EVs of various sizes, namely microvesicles (ranging from 100–1000 nm) or exosomes (with sizes between 30–150 nm) are released by most eukaryotic cells. EVs are known to contain bioactive molecules including proteins lipids and nucleic acids including miRNAs and LNC RNAs that regulate gene expression and cell functions in recipient cells. For example, tumour released exosomes remodel the microenvironment allowing cancer cells to survive and thrive. Low oxygen (hypoxia) is known to increase the release of exosomes in cancer cells. Hypoxia leads to the activation of hypoxia inducible factor (HIF) transcription factors, considered master regulators of the hypoxic response. The objective of this study was to investigate whether hypoxia induced EV (exosome) release is dependent on hypoxia inducible factor (HIF) proteins.MethodsWe isolated exosomes and microvesicles by differential centrifugation of conditioned media of cells exposed to normoxia or hypoxia (1% Oxygen) for different lengths of time ranging from 1–24hrs. We determined, size distribution and concentration of vesicles by nanoparticle tracking analysis (NTA). Expression of HIF1 and HIF2 was monitored by western blot of cellular lysates. We expressed oxygen‐stable mutated HIF1 and HIF2 isoforms either alone or in combination and determined EV release by NTA. We used chemical inhibitors of dioxygenase (PHD) and von Hippel–Lindau (VHL) proteins, the two proteins involved in HIF degradation under oxygen conditions, to stabilize HIF expression in normoxic cells and analysed EV release and HIF expression. We also analysed EV release in a cell line lacking VHL and after a VHL knock‐in. Western blotting of cellular lysates was used to monitor HIFs, VHL, and VEGF proteins. NTA was used to determine EV concentration and size. ANOVA statistical analysis was performed to analyse the data.ResultsHypoxia increased the amount extracellular vesicles in the conditioned media of all cells tested. The release of small vesicles (exosomes) was most increased following the exposure to hypoxia. HIF protein expression increased steadily during the time course of hypoxia, reaching a plateau after 2hrs following exposure. Expression of mutated (oxygen stable) HIF1 and HIF2 proteins in normoxic cells, either alone or in combination, did not increase exosome release. Chemical inhibition of PHD or VHL did not affect EV release. Exosome release was not different in VHL KD or KI cells.Conclusionthese data suggest that hypoxia driven exosome release is HIF independent.Support or Funding InformationSponsored by Fundacion Ramon Areces

Mitochondrial energy metabolism mediated via HIF-1 involves the proliferation and apoptosis of renal clear cell carcinoma cells regulated by propofol

Objective To investigate the role of mitochondrial energy metabolism mediated via hypoxia-inducible factor-1 (HIF-1) in the proliferation and apoptosis of renal clear cell carcinoma cells regulated by propofol. Methods We chose human renal clear cell carcinoma cell line RCC4 as the research object, which did not express VHL gene. The pcDNA3-VHL plasmid and the pcDNA3 empty plasmid were respectively transfected into RCC4 cells to obtain RCC4-VHL(+ ) cells stably expressing the exogenous VHL protein and RCC4-VHL(-) cells without expressing the VHL protein. These two kinds of cells were then exposed to propofol at dosage of 0, 25, 50 and 100 μmol/L. HIF-1 protein expression was detected by Western blotting in the two kinds of cells, cell proliferation activity and apoptosis rate were detected by flow cytometry, and mitochondrial energy metabolism was detected by energy metabolism analyzer. Results Compared with RCC4-VHL(-) cells, the relative expression of HIF-1α protein in RCC4-VHL(+ ) cells was significantly decreased (0.05±0.02 vs. 1.23±0.10, t=16.016, P<0.001). When propofol concentrations were 50 μmol/L and 100 μmol/L, the proliferation activity of RCC4-VHL(+ ) cells was significantly lower than that of RCC4-VHL(-) cells (50 μmol/L: 0.10±0.02 vs. 0.13±0.04, t=3.502, P=0.032; 100 μmol/L: 0.05±0.02 vs. 0.10±0.01, t=6.771, P=0.017), and the apoptotic rate was significantly higher than that of RCC4-VHL (-) cells [50 μmol/L: (35.50±1.84)% vs. (22.15±1.06)%, t=7.082, P=0.004; 100 μmol/L: (54.35±2.97)% vs. (35.10±3.25)%, t=10.241, P<0.001). Compared with 0 μmol/L propofol, 100 μmol/L propofol increased HIF-1α protein expression in RCC4-VHL (+ ) cells (0.93±0.05 vs. 0.04±0.02, t=18.500, P<0.001). Compared with RCC4-VHL(-) cells, the oxygen consumption rate (OCR) [(130.42±11.81) pmol/min vs. (48.27±7.66) pmol/min, t=11.672, P<0.001], basal aerobic respiration [(98.55±8.09) pmol/min vs. (41.63±6.21) pmol/min, t=11.162, P<0.001], aerobic maximum [(226.79±13.51) pmol/min vs. (70.18±6.82) pmol/min, t=20.697, P<0.001], non-mitochondrial respiration [(28.36±4.29) pmol/min vs. (8.92±1.70) pmol/min, t=8.426, P=0.001] and oxygen consumption rate of proton leak [(23.85±5.08) pmol/min vs. (7.80±1.24) pmol/min, t=6.139, P=0.006] were significantly increased in RCC4-VHL(+ ) cells, while the extracellular acidification rate (ECAR) was significantly decreased [(26.76±4.35) mpH/min vs. (39.48±5.17) mpH/min, t=3.765, P=0.010]. Compared with 0 μmol/L propofol added in RCC4-VHL(+ ) cells, 100 μmol/L propofol decreased OCR [(72.44±8.15) pmol/min vs. (131.56±9.04) pmol/min, t=9.751, P<0.001], basal aerobic respiration [(54.31±5.35) pmol/min vs. (96.49±6.86) pmol/min, t=9.697, P<0.001], aerobic maximum [(116.71±12.39) pmol/min vs. (219.53±11.80) pmol/min, t=12.019, P<0.001], non-mitochondrial respiration [(13.25±4.01) pmol/min vs. (29.04±5.11) pmol/min, t=4.862, P=0.002] and oxygen consumption rate of proton leak [(10.24±3.79) pmol/min vs. (22.92±4.12) pmol/min, t=4.530, P=0.003], and increased ECAR significantly [(37.69±3.75) mpH/min vs. (25.87±4.03) mpH/min, t=4.294, P=0.004]. Conclusion Loss of VHL up-regulates expression of HIF-1 protein, and mitochondrial energy metabolism mediated via HIF-1 involves the proliferation and apoptosis of RCC4 cells regulated by propofol. Key words: Hypoxia-inducible factor 1; Energy metabolism; Propofol; Cell proliferation; Renal clear cell carcinoma

Administration of human umbilical cord blood mononuclear cells restores bladder dysfunction in streptozotocin-induced diabetic rats.

This study evaluated the effect of human umbilical cord blood mononuclear cells (HUCB-MNCs) on bladder dysfunction in streptozotocin (STZ; 35 mg/kg, i.v.)-induced diabetic rats. Adult male Sprague-Dawley rats (n = 30) were equally divided into three groups: control group, STZ-diabetic group, and HUCB-MNC-treated group (1 × 106 cells). HUCB-MNCs were isolated by density gradient centrifugation from eight healthy donors and injected into the corpus cavenosum in STZ-diabetic rats 4 weeks after the induction of diabetes. Studies were performed 4 weeks after HUCB-MNC or vehicle injection. In vitro organ bath studies were performed on bladder strips, whereas protein expression of hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and α-smooth muscle actin (SMA) in the bladder and the ratio of smooth muscle cells (SMCs) to collagen were determined using western blotting and Masson trichrome staining. Neurogenic contractions of detrusor smooth muscle strips were 55% smaller in the diabetic group than control group (P < 0.05); these contractions were normalized by HUCB-MNC treatment. In addition, HUCB-MNC treatment restored the impaired maximal carbachol-induced contractile response in detrusor strips in the diabetic group (29%; P < 0.05). HUCB-MNC treatment improved the KCl-induced contractile response in the diabetic bladder (68%; P < 0.05), but had no effect on ATP-induced contractile responses. Increased expression of HIF-1α and VEGF protein and decreased expression of α-SMA protein and the SMC/collagen ratio in diabetic rats were reversed by HUCB-MNC. Administration of HUCB-MNCs facilitates bladder function recovery, which is likely related to downregulation of HIF-1α expression and attenuation of fibrosis in STZ-diabetic rats.

Aggregation of human dental pulp cells into 3D spheroids enhances their migration ability after reseeding.

Multicellular three-dimensional (3D) spheroids allow intimate cell-cell communication and cell-extracellular matrix interaction. Thus, 3D cell spheroids better mimic microenvironment in vivo than two-dimensional (2D) monolayer cultures. The purpose of this study was to evaluate the behaviors of human dental pulp cells (DPCs) cultured on chitosan and polyvinyl alcohol (PVA) membranes. The protein expression of hypoxia-inducible factor 1-α (HIF-1α) and vascular endothelial growth factor (VEGF), and the migration ability of the DPCs from 2D versus 3D environments were investigated. The results showed that both chitosan and PVA membranes support DPCs aggregation to form multicellular spheroids. In comparison to 2D cultures on tissue culture polystyrene, DPC spheroids exhibited higher protein expression of HIF-1α and VEGF. The treatment with YC-1 (inhibitor to HIF-1α) blocked the upregulation of VEGF, indicating a downstream event to HIF-1α expression. When DPC spheroids were collected and subjected to the transwell assay, the cells growing outward from 3D spheroids showed greater migration ability than those from 2D cultures. Moreover, DPCs aggregation and spheroid formation on chitosan membrane were abolished by Y-27632 (inhibitor to Rho-associated kinases), whereas the inhibitory effect did not exist on PVA membrane. This suggests that the mechanism regulating DPCs aggregation and spheroid formation on chitosan membrane is involved with the Rho-associated kinase signaling pathway. In summary, the multicellular spheroid structure was beneficial to the protein expression of HIF-1α and VEGF in DPCs and enhanced the migration ability of the cells climbing from spheroids. This study showed a new perspective in exploring novel strategies for DPC-based research and application.

Pioglitazone induces hypoxia-inducible factor 1 activation in human renal proximal tubular epithelial cell line HK-2

We previously reported that fatty acid-bearing albumin but not fatty acid-depleted albumin induces hypoxia-inducible factor-1 (HIF-1) activation in human renal proximal tubular epithelial cell line HK-2. Then, an increase in mRNA expression of peroxisome proliferator-activated receptor gamma (PPARγ) was observed on treatment with fatty acid-bearing albumin but not fatty acid-depleted albumin. The aim of this study was to determine whether a PPARγ agonist, pioglitazone, induces HIF-1 activation or not. Treatment with pioglitazone induced HIF-1α mRNA as well as PPARγ mRNA expression in a concentration dependent manner. In addition, pioglitazone increased HIF-1 target genes such as the mRNAs of glucose transporter 1 (GLUT1) and breast cancer resistance protein (BCRP/ABCG2), in a concentration-dependent manner. Consistent with the increases in GLUT1 and ABCG2 mRNAs, protein expression of GLUT1 and BCRP was increased by pioglitazone. In addition, GLUT inhibitor phloretin-sensitive D-[3H]glucose uptake activity and BCRP inhibitor Ko143-sensitive accumulation of Hoecsht33342, a BCRP substrate, were significantly enhanced by treatment with pioglitazone. These findings suggest that PPARγ activation by pioglitazone leads to HIF-1 protein expression induction followed by changes in HIF-1 target gene expression and protein product activity.

Propranolol reduces viability and induces apoptosis in hemangioblastoma cells from von Hippel-Lindau patients.

BackgroundVon Hippel-Lindau (VHL) disease is a rare oncological disease with an incidence of 1:36,000, and is characterized by the growth of different types of tumors: hemangioblastomas in the central nervous system (CNS) and retina, renal carcinoma, pheochromocytomas, pancreatic serous cystadenoma, and endolymphatic sac tumors. These tumors do not express VHL protein (pVHL). pVHL ubiquitinates hypoxia inducible factor (HIF) protein for degradation by the proteasome; in the absence of VHL, HIF translocates to the nucleus to activate the expression of its target genes. Targeting VHL-derived tumors with drugs that have reduced side effects is urgent to avoid repeat CNS surgeries. Recent reports have shown that propranolol, a β-blocker used for the treatment of hypertension and other cardiac and neurological diseases, is the best option for infantile hemangioma (IH). Propranolol could be an efficient treatment to control hemangioblastoma growth in VHL disease because of its antiangiogenic effects demonstrated in IH and the hypothetical impact on HIF levels.MethodsHeLa 9X (HRE) hypoxia responsive element cell line and primary hemangioblastoma-derived cells were subjected to propranolol treatment and cell viability and apoptosis were evaluated. HIF1-α and Hif-2α expression after propranolol treatment was analyzed by western blotting. Quantitative PCR was performed to study the mRNA expression of HIF target genes. Vascular endothelial growth factor (VEGF) was measured in culture supernatants by immunoassay.ResultsPropranolol downregulated HIF-dependent transcription in HeLa 9XHRE cells. Under hypoxic conditions, propranolol decreased the expression of HIF target genes in hemangioblastoma cells, which stopped proliferating and died following long-term treatment. These results suggests that propranolol treatment promoted reduced HIF protein expression and corresponding downregulation of HIF target genes, and inhibited cell proliferation in parallel with induction of cell death by apoptosis.ConclusionsOur results suggest that propranolol could reduce the growth of HIF-dependent tumors and may thus be a promising treatment to delay surgery in VHL patients.

MicroRNA-210 is involved in the regulation of postmenopausal osteoporosis through promotion of VEGF expression and osteoblast differentiation.

MicroRNAs (miRNAs) are small non-protein-codingRNAs that function as negative gene expression regulators. miRNA-210 (miR-210) has recently been recognized in the pathogenesis of osteonecrosis associated with angiogenesis. Herein we aimed to explore the clinical significance of miR-210 treatment for postmenopausal osteoporosis. The expression of miR-210 was detected in bone marrow mesenchymal stem cells (BMSCs) in vitro and miR-210 significantly promoted the expression of vascular edothelial growth factor (VEGF) in BMSCs in a time-dependent manner (p<0.05). And miR-210 suppressed PPARγ expression but increased the expression of ALP and osterix, demonstrating that miR-210 inhibited adipocyte differentiation and promoted osteoblast differentiation of BMSCs in vitro. The protein expression of hypoxia-inducible factor 1 alpha (HIF-1α) and VEGF in 17β-estradiol (E2) treated osteoblasts were significantly increased in a dose- and time-dependent manner (p<0.05). And E2 inducted the VEGF expression through the PI3K/AKT signaling pathway in osteoblasts. Taken together, these data implied that miR-210 played an important role in ameliorating the estrogen deficiency caused-postmenopausal osteoporosis through promotion the VEGF expression and osteoblast differentiation.

A Huaier polysaccharide restrains hepatocellular carcinoma growth and metastasis by suppression angiogenesis

Hepatocellular carcinoma (HCC) is a highly metastatic cancer. Huaier polysaccharide (TP-1) is a naturally occurring bioactive macromolecule, found in Huaier fungus and has been shown to exert in vitro antitumor and antimetastasis for HCC, but no study has addressed in vivo efficacy and mechanisms of action. Presently, we found that TP-1 at doses of 0.5, 1 and 2mg/kg significantly inhibited tumor growth and metastasis to the lung in mice bearing HCC SMMC-7721 tumors without toxicity. The analysis of tumors by immunohistochemistry demonstrated that TP-1 inhibited PCNA expression, increased the number of TUNEL-positive cells and reduced microvessel density (MVD) to achieve this effect. Furthermore, TP-1 administration reduced the protein expression of hypoxia-inducible factor (HIF)-1alpha, vascular endothelial growth factor (VEGF), AUF-1 and AEG-1, in tumor tissues. Taken together, our data suggested that the antitumor and anti-metastatic activities of TP-1 might be at least partially through down-regulation of HIF-1alpha/VEGF and AUF-1/AEG-1 signaling pathways.

Retraction note to: the hypoxia-inducible factor-1 regulates the microRNA185 expression through binding to hypoxia response elements sequence 2.

This study aimed to investigate the interaction and regulatory mechanism of microRNA185 (miR185) and hypoxia-inducible factor-1 (HIF-1) in pancreatic cancer. The significance of miR185 on the clinicopathologic characteristics and prognosis was further explored. qRT-PCR and immunohistochemistry examined miR185 and HIF-1 expression of tumor tissues. Western blot analyzed HIF-1 protein expression. We regulated HIF-1 via transfection to observe the impact of HIF-1 on miR185 expression. ChIP sequencing and dual luciferase identified binding sites of HIF-1 and miR185. MiR185 expression was significantly higher in pancreatic tumors. MiR185 closely associated with tumor size, pTNM stage, lymph node, and perneural invasion. After hypoxic culture, both HIF-1 and miR185 expression of MiaPaCa2 and AsPc1 cells increased significantly. Up- or down-regulating HIF-1 expression via transfection leads to synchronous alteration of miR185. In ChIP sequencing, only the HRE2 (−938 bp) was significantly brighter under hypoxia among four hypoxia response elements’ (HREs) sequence of miR185 promoter. After pGL3-miR185 and HIF-1 over-expressing plasmids co-transfect the MiaPaCa2 cells, its relative expression of bioluminescence increased. MiR185 expression was significantly higher in tumor tissues and closely associated with the clinical features of pancreatic cancer. Expression of HIF-1 in pancreatic cancer cells increased in hypoxia. HIF-1 may bind to HRE2 of miR185 and initiate its transcription.

A polysaccharide from mushroom Huaier retards human hepatocellular carcinoma growth, angiogenesis, and metastasis in nude mice.

Mushroom Huaier has become a focus of interest in the treatment of hepatocellular carcinoma (HCC). Presently, we isolated and purified one polysaccharide from this mushroom. This study aimed to investigate the effects of SP1 on tumor growth and metastasis in a HCC xenograft model and explore its possible mechanism of action. Our results showed that SP1 not only significantly inhibited the proliferation of SMMC-7721 cells in vitro at the concentration ranging from 0 to 800μg/ml but also suppressed the HCC tumor growth and metastatic nodules to the lung in SMMC-7721-bearing mice by oral administration at three doses of 30, 60, and 120mg/kg. Concomitantly, immunohistochemistry analysis of tumor tissues identified that SP1 administration at three doses significantly inhibited the in vivo cancer cell proliferation and microvessel density (MVD) formation, evidenced by a low proliferating cell nuclear antigen (PCNA) and CD34 expression, but increased the percentage of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells. Keeping in line with this observation, SP1 treatment decreased serum matrix metalloproteinase (MMP) 2 and vascular endothelial growth factor (VEGF) levels, downregulated the protein expression of hypoxia-inducible factor (HIF)-1alpha, VEGF, MMP2, bcl-2, N-cadherin, signal transducer and activator of transcription 3 (STAT3), and metadherin (MTDH), and upregulated bax and NE-cadherin protein expression in tumor tissues. Taken together, our data suggest that SP1 appears to be a promising chemopreventive agent for the tumorigenesis and metastasis in patients with HCC, especially at advanced stages.

Differential roles of prostaglandin E-type receptors in activation of hypoxia-inducible factor 1 by prostaglandin E1in vascular-derived cells under non-hypoxic conditions

Prostaglandin E1 (PGE1), known pharmaceutically as alprostadil, has vasodilatory properties and is used widely in various clinical settings. In addition to acute vasodilatory properties, PGE1 may exert beneficial effects by altering protein expression of vascular cells. PGE1 is reported to be a potent stimulator of angiogenesis via upregulation of VEGF expression, which is under the control of the transcription factor hypoxia-inducible factor 1 (HIF-1). However, the molecular mechanisms behind the phenomenon are largely unknown. In the present study, we investigated the mechanism by which PGE1 induces HIF-1 activation and VEGF gene expression in human aortic smooth muscle cells (HASMCs) and human umbilical vein endothelial cells (HUVECs), both vascular-derived cells. HUVECs and HASMCs were treated with PGE1 at clinically relevant concentrations under 20% O2 conditions and HIF-1 protein expression was investigated. Expression of HIF- 1α protein and the HIF-1-downstream genes were low under 20% O2 conditions and increased in response to PGE1 treatment in both HUVECs and HASMCs in a dose- and time-dependent manner under 20% O2 conditions as comparable to exposure to 1% O2 conditions. Studies using EP-receptor-specific agonists and antagonists revealed that EP1 and EP3 are critical to PGE1-induced HIF-1 activation. In vitro vascular permeability assays using HUVECs indicated that PGE1 increased vascular permeability in HUVECs. Thus, we demonstrate that PGE1 induces HIF- 1α protein expression and HIF-1 activation under non-hypoxic conditions and also provide evidence that the activity of multiple signal transduction pathways downstream of EP1 and EP3 receptors is required for HIF-1 activation.

RETRACTED ARTICLE: The hypoxia-inducible factor-1 regulates the microRNA185 expression through binding to hypoxia response elements sequence 2

This study aimed to investigate the interaction and regulatory mechanism of microRNA185 (miR185) and hypoxia-inducible factor-1 (HIF-1) in pancreatic cancer. The significance of miR185 on the clinicopathologic characteristics and prognosis was further explored. qRT-PCR and immunohistochemistry examined miR185 and HIF-1 expression of tumor tissues. Western blot analyzed HIF-1 protein expression. We regulated HIF-1 via transfection to observe the impact of HIF-1 on miR185 expression. ChIP sequencing and dual luciferase identified binding sites of HIF-1 and miR185. MiR185 expression was significantly higher in pancreatic tumors. MiR185 closely associated with tumor size, pTNM stage, lymph node, and perneural invasion. After hypoxic culture, both HIF-1 and miR185 expression of MiaPaCa2 and AsPc1 cells increased significantly. Up- or down-regulating HIF-1 expression via transfection leads to synchronous alteration of miR185. In ChIP sequencing, only the HRE2 (-938 bp) was significantly brighter under hypoxia among four hypoxia response elements' (HREs) sequence of miR185 promoter. After pGL3-miR185 and HIF-1 over-expressing plasmids co-transfect the MiaPaCa2 cells, its relative expression of bioluminescence increased. MiR185 expression was significantly higher in tumor tissues and closely associated with the clinical features of pancreatic cancer. Expression of HIF-1 in pancreatic cancer cells increased in hypoxia. HIF-1 may bind to HRE2 of miR185 and initiate its transcription.

The effect of HS-111, a novel thiazolamine derivative, on apoptosis and angiogenesis of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common malignancies, yet there have been no significant advances in effective therapeutics. In this study, HS-111 was synthesized as a novel thiazolamine derivative, N-(5-(2-chlorobenzyl) thiazole-2-yl) benzofuran-2-carboxamide, and its anticancer effect and mechanism were examined in human HCC cells. HS-111 strongly suppressed the growth of HCC cells in a dose-dependent manner. Also, apoptosis by HS-111 was identified by DAPI and TUNEL staining, and the increases of the cleaved caspase-3 were observed. In addition, HS-111 decreased protein expression of hypoxia-inducible factor (HIF-1α) and secretion of vascular endothelial growth factor (VEGF), and inhibited tube formation and the migration of human umbilical vein endothelial cells (HUVECs). These results showed that HS-111 not only inhibited cell growth and angiogenesis, but also induced apoptosis of human HCC cells. We suggest that HS-111 may be a potential candidate for chemotherapy against HCC.

Myc Posttranscriptionally Induces HIF1 Protein and Target Gene Expression in Normal and Cancer Cells

c-Myc is frequently overexpressed in tumors and plays an important role in the regulation of cancer metabolism. Hypoxia-inducible factor-1 (HIF1), the master regulator of the hypoxic response, enhances tumorigenesis and influences metabolism via upregulation of the glycolytic pathway and suppression of mitochondrial respiration. Together, deregulated Myc and HIF1 cooperate to lend metabolic advantages to proliferating cancer cells and contribute to the Warburg effect. Here we show that overexpression of Myc significantly stabilizes the α subunit of HIF1 (HIF1α) under normoxic conditions and enhances HIF1α accumulation under hypoxic conditions in cells. Posttranscriptional regulation of HIF1α by Myc led to the induction of HIF1α gene targets. Normoxic HIF1α protein expression was also dependent on Myc. Functionally, HIF1α expression was required for Myc-induced anchorage-independent growth and cell proliferation. Myc-dependent stabilization of HIF1α involved either disruption of binding to the VHL complex or posttranslational protein modifications. Taken together, our findings uncover a previously uncharacterized regulatory relationship between Myc and HIF1 that has important implications for cancer metabolism and development.

Comparative analysis of novel and conventional Hsp90 inhibitors on HIF activity and angiogenic potential in clear cell renal cell carcinoma: implications for clinical evaluation

BackgroundPerturbing Hsp90 chaperone function targets hypoxia inducible factor (HIF) function in a von Hippel-Lindau (VHL) independent manner, and represents an approach to combat the contribution of HIF to cell renal carcinoma (CCRCC) progression. However, clinical trials with the prototypic Hsp90 inhibitor 17-AAG have been unsuccessful in halting the progression of advanced CCRCC.MethodsHere we evaluated a novel next generation small molecule Hsp90 inhibitor, EC154, against HIF isoforms and HIF-driven molecular and functional endpoints. The effects of EC154 were compared to those of the prototypic Hsp90 inhibitor 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589.ResultsThe findings indicate that EC154 is a potent inhibitor of HIF, effective at doses 10-fold lower than 17-AAG. While EC154, 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589 impaired HIF transcriptional activity, CCRCC cell motility, and angiogenesis; these effects did not correlate with their ability to diminish HIF protein expression. Further, our results illustrate the complexity of HIF targeting, in that although these agents suppressed HIF transcripts with differential dynamics, these effects were not predictive of drug efficacy in other relevant assays.ConclusionsWe provide evidence for EC154 targeting of HIF in CCRCC and for LBH589 acting as a suppressor of both HIF-1 and HIF-2 activity. We also demonstrate that 17-AAG and EC154, but not LBH589, can restore endothelial barrier function, highlighting a potentially new clinical application for Hsp90 inhibitors. Finally, given the discordance between HIF activity and protein expression, we conclude that HIF expression is not a reliable surrogate for HIF activity. Taken together, our findings emphasize the need to incorporate an integrated approach in evaluating Hsp90 inhibitors within the context of HIF suppression.