OBJECTIVE: To identify and characterize read-through RNAs and read-through circular RNAs (rt-circ-HS) derived from transcriptional read-through hypoxia inducible factor 1α (HIF1α) and small nuclear RNA activating complex polypeptide 1 (SNAPC1) the two adjacent genes located on chromosome 14q23, in renal carcinoma cells and renal carcinoma tissues, and to study the effects of rt-circ-HS on biological behavior of renal carcinoma cells and on regulation of HIF1α. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and Sanger sequencing were used to examine expression of read-through RNAs HIF1α-SNAPC1 and rt-circ-HS in different tumor cells. Tissue microarrays of 437 different types of renal cell carcinoma (RCC) were constructed, and chromogenic in situ hybridization (ISH) was used to investigate expression of rt-circ-HS in different RCC types. Small interference RNA (siRNA) and artificial overexpression plasmids were designed to examine the effects of rt-circ-HS on 786-O and A498 renal carcinoma cell proliferation, migration and invasiveness by cell counting kit 8 (CCK8), EdU incorporation and Transwell cell migration and invasion assays. RT-PCR and Western blot were used to exa-mine expression of HIF1α and SNAPC1 RNA and proteins after interference of rt-circ-HS with siRNA, respectively. The binding of rt-circ-HS with microRNA 539 (miR-539), and miR-539 with HIF1α 3' untranslated region (3' UTR), and the effects of these interactions were investigated by dual luciferase reporter gene assays. RESULTS: We discovered a novel 1 144 nt rt-circ-HS, which was derived from read-through RNA HIF1α-SNAPC1 and consisted of HIF1α exon 2-6 and SNAPC1 exon 2-4. Expression of rt-circ-HS was significantly upregulated in 786-O renal carcinoma cells. ISH showed that the overall positive expression rate of rt-circ-HS in RCC tissue samples was 67.5% (295/437), and the expression was different in different types of RCCs. Mechanistically, rt-circ-HS promoted renal carcinoma cell proliferation, migration and invasiveness by functioning as a competitive endogenous inhibitor of miR-539, which we found to be a potent post-transcriptional suppressor of HIF1α, thus promoting expression of HIF1α. CONCLUSION The novel rt-circ-HS is highly expressed in different types of RCCs and acts as a competitive endogenous inhibitor of miR-539 to promote expression of its parental gene HIF1α and thus the proliferation, migration and invasion of renal cancer cells.
Humans ; Carcinoma, Renal Cell/pathology* ; Cell Proliferation ; Hypoxia ; Kidney Neoplasms ; MicroRNAs/genetics* ; Neoplasm Invasiveness/genetics* ; RNA, Circular/metabolism* ; RNA, Small Interfering ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics*

Chromodomain-helicase-DNA-binding protein 1 (CHD1) deletion is among the most common mutations in prostate cancer (PCa), but its role remains unclear. In this study, RNA sequencing was conducted in PCa cells after clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9)-based CHD1 knockout. Gene set enrichment analysis (GSEA) indicated upregulation of hypoxia-related pathways. A subsequent study confirmed that CHD1 deletion significantly upregulated hypoxia-inducible factor 1α (HIF1α) expression. Mechanistic investigation revealed that CHD1 deletion upregulated HIF1α by transcriptionally downregulating prolyl hydroxylase domain protein 2 (PHD2), a prolyl hydroxylase catalyzing the hydroxylation of HIF1α and thus promoting its degradation by the E3 ligase von Hippel-Lindau tumor suppressor (VHL). Functional analysis showed that CHD1 deletion promoted angiogenesis and glycolysis, possibly through HIF1α target genes. Taken together, these findings indicate that CHD1 deletion enhances HIF1α expression through PHD2 downregulation and therefore promotes angiogenesis and metabolic reprogramming in PCa.
Male ; Humans ; Von Hippel-Lindau Tumor Suppressor Protein/metabolism* ; DNA-Binding Proteins/metabolism* ; Prolyl Hydroxylases/metabolism* ; Hypoxia ; Prostatic Neoplasms/pathology* ; Glycolysis ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Cell Line, Tumor ; DNA Helicases/metabolism*

OBJECTIVE: To investigate the expression and its relative mechanism of hypoxia-inducible factor-1α(HIF-1α) in bone marrow(BM) of mice during G-CSF mobilization of hematopoietic stem cells (HSC) . METHODS: Flow cytometry was used to detect the proportion of Lin^-Sca-1⁺ c-kit⁺ (LSK) cells in peripheral blood of C57BL/6J mice before and after G-CSF mobilization. And the expression of HIF-1α and osteocalcin (OCN) mRNA and protein were detected by RQ-PCR and immunohistochemistry. The number of osteoblasts in bone marrow specimens of mice was counted under the microscope. RESULTS: The proportion of LSK cells in peripheral blood began to increase at day 4 of G-CSF mobilization, and reached the peak at day 5, which was significantly higher than that of control group (P<0.05). There was no distinct difference in the expression of HIF-1α mRNA between bone marrow nucleated cells and osteoblasts of steady-state mice (P=0.073), while OCN mRNA was mainly expressed in osteoblasts, which was higher than that in bone marrow nucleated cells (P=0.034). After mobilization, the expression level of HIF-1α increased, but OCN decreased, and the number of endosteum osteoblasts decreased. The change of HIF-1α expression was later than that of OCN and was consistent with the proportion of LSK cells in peripheral blood. CONCLUSION The expression of HIF-1α in bone marrow was increased during the mobilization of HSC mediated by G-CSF, and one of the mechanisms may be related to the peripheral migration of HSC induced by osteoblasts inhibition.
Mice ; Animals ; Hematopoietic Stem Cell Mobilization ; Granulocyte Colony-Stimulating Factor/pharmacology* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Mice, Inbred C57BL ; Bone Marrow Cells/metabolism* ; Osteocalcin/metabolism* ; RNA, Messenger/metabolism*

Hypoxia, as an important hallmark of the tumor microenvironment, is a major cause of oxidative stress and plays a central role in various malignant tumors, including glioblastoma. Elevated reactive oxygen species (ROS) in a hypoxic microenvironment promote glioblastoma progression; however, the underlying mechanism has not been clarified. Herein, we found that hypoxia promoted ROS production, and the proliferation, migration, and invasion of glioblastoma cells, while this promotion was restrained by ROS scavengers N-acetyl-L-cysteine (NAC) and diphenyleneiodonium chloride (DPI). Hypoxia-induced ROS activated hypoxia-inducible factor-1α (HIF-1α) signaling, which enhanced cell migration and invasion by epithelial-mesenchymal transition (EMT). Furthermore, the induction of serine protease inhibitor family E member 1 (SERPINE1) was ROS-dependent under hypoxia, and HIF-1α mediated SERPINE1 increase induced by ROS via binding to the SERPINE1 promoter region, thereby facilitating glioblastoma migration and invasion. Taken together, our data revealed that hypoxia-induced ROS reinforce the hypoxic adaptation of glioblastoma by driving the HIF-1α-SERPINE1 signaling pathway, and that targeting ROS may be a promising therapeutic strategy for glioblastoma.
Humans ; Cell Hypoxia ; Cell Line, Tumor ; Glioblastoma/pathology* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Plasminogen Activator Inhibitor 1/metabolism* ; Reactive Oxygen Species/metabolism* ; Signal Transduction ; Tumor Microenvironment ; Brain Neoplasms/pathology*

Accumulating evidence has confirmed the links between transfer RNA (tRNA) modifications and tumor progression. The present study is the first to explore the role of tRNA methyltransferase 5 (TRMT5), which catalyzes the m1G37 modification of mitochondrial tRNAs in hepatocellular carcinoma (HCC) progression. Here, based on bioinformatics and clinical analyses, we identified that TRMT5 expression was upregulated in HCC, which correlated with poor prognosis. Silencing TRMT5 attenuated HCC proliferation and metastasis both in vivo and in vitro, which may be partially explained by declined extracellular acidification rate (ECAR) and oxygen consumption rate (OCR). Mechanistically, we discovered that knockdown of TRMT5 inactivated the hypoxia-inducible factor-1 (HIF-1) signaling pathway by preventing HIF-1α stability through the enhancement of cellular oxygen content. Moreover, our data indicated that inhibition of TRMT5 sensitized HCC to doxorubicin by adjusting HIF-‍1α. In conclusion, our study revealed that targeting TRMT5 could inhibit HCC progression and increase the susceptibility of tumor cells to chemotherapy drugs. Thus, TRMT5 might be a carcinogenesis candidate gene that could serve as a potential target for HCC therapy.
Humans ; Carcinoma, Hepatocellular/pathology* ; Cell Hypoxia ; Cell Line, Tumor ; Gene Expression Regulation, Neoplastic ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Liver Neoplasms/pathology* ; Signal Transduction/genetics* ; tRNA Methyltransferases/metabolism*

Metabolic reprogramming is a common phenomenon in cancer, with aerobic glycolysis being one of its important characteristics. Hypoxia-inducible factor-1α (HIF1Α) is thought to play an important role in aerobic glycolysis. Meanwhile, naringin is a natural flavanone glycoside derived from grapefruits and many other citrus fruits. In this work, we identified glycolytic genes related to HIF1Α by analyzing the colon cancer database. The analysis of extracellular acidification rate and cell function verified the regulatory effects of HIF1Α overexpression on glycolysis, and the proliferation and migration of colon cancer cells. Moreover, naringin was used as an inhibitor of colon cancer cells to illustrate its effect on HIF1Α function. The results showed that the HIF1Α and enolase 2 (ENO2) levels in colon cancer tissues were highly correlated, and their high expression indicated a poor prognosis for colon cancer patients. Mechanistically, HIF1Α directly binds to the DNA promoter region and upregulates the transcription of ENO2; ectopic expression of ENO2 increased aerobic glycolysis in colon cancer cells. Most importantly, we found that the appropriate concentration of naringin inhibited the transcriptional activity of HIF1Α, which in turn decreased aerobic glycolysis in colon cancer cells. Generally, naringin reduces glycolysis in colon cancer cells by reducing the transcriptional activity of HIF1Α and the proliferation and invasion of colon cancer cells. This study helps to elucidate the relationship between colon cancer progression and glucose metabolism, and demonstrates the efficacy of naringin in the treatment of colon cancer.
Glycolysis ; Colonic Neoplasms/metabolism* ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Phosphopyruvate Hydratase/metabolism* ; Flavanones/pharmacology* ; Cell Line, Tumor ; Databases, Genetic ; Cell Proliferation/drug effects* ; Transfection ; Warburg Effect, Oncologic

Hypoxia inducible factor-1α (HIF-1α), as a hypoxia inducible factor, affects women's reproductive function by regulating the development and excretion of follicles. HIF-1α induces glycolysis and autophagy in the granule cells by promoting oocyte development, regulating the secretion of related angiogenic factors, and improving follicle maturity. In addition, HIF-1α promotes the process of luteinization of follicular vesicles, maintains luteal function, and finally completes physiological luteal atrophy through cumulative oxidative stress. Dysfunction of HIF-1α will cause a series of pathological consequences, such as angiogenesis defect, energy metabolism abnormality, excessive oxidative stress and dysregulated autophagy and apoptosis, resulting in ovulation problem and infertility. This article summarizes the previous studies on the regulation of follicle development and excretion and maintenance of luteal function and structural atrophy by HIF-1α. We also describe the effective intervention mechanism of related drugs or bioactive ingredients on follicular dysplasia and ovulation disorders through HIF-1α, in order to provide a systematic and in-depth insights for solving ovulation disorder infertility.
Female ; Humans ; Atrophy/metabolism* ; Hypoxia ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Infertility/metabolism* ; Ovarian Follicle ; Ovulation

OBJECTIVE: To observe the effect of Biantie (bian stone plaste) pretreatment on serum level of prolyl hydroxylase domain 2 (PHD2) and hypoxia-inducible factor-1α (HIF-1α) in rats with acute hypobaric hypoxia induced-brain injury, and to explore the possible mechanism of Biantie on preventing brain injury at high altitude. METHODS: Forty-five male SD rats were randomly divided into a blank group, a model group, a Biantie group, a medication group and a Biantie+inhibitor group, 9 rats in each group. The rats in the Biantie group the and the Biantie+inhibitor group were pretreated with Biantie at "Taiyuan" (LU 9), "Neiguan" (PC 6) and "Renying" (ST 9), 2 h each time, once a day; the rats in the medication group were treated with intragastric administration of rhodiola capsule solution (280 mg/kg) for 14 d; the rats in the Biantie+inhibitor group were intraperitoneally injected with the PHD inhibitor dimethyloxalyl glycine (DMOG) at a dose of 40 mg/kg 24 h before the establishment of the model. After the intervention, except for the blank group, the rats in the remaining 4 groups were placed in the oxygen chamber to simulate a high-altitude environment to establish the acute hypobaric hypoxia brain injury model. The arterial blood-gas analysis indexes [blood oxygen saturation (SaO₂), lactic acid (Lac), blood sodium (Na⁺), blood potassium (K⁺)] and brain water content were detected in each group; the histomorphology of cerebral cortex was observed by HE staining; the serum levels of PHD2 and HIF-1α as well as vascular endothelial growth factor (VEGF) were detected by ELISA; the VEGF protein expression in brain tissue was detected by Western blot; the VEGF mRNA expression in brain tissue was detected by real-time fluorescent quantitative PCR. RESULTS: Compared with the blank group, the levels of SaO₂ and Na⁺ in the model group were decreased (P<0.05), while the levels of Lac and K⁺ as well as the water content of brain tissue were increased (P<0.05). Compared with the model group, the level of SaO₂ in the Biantie group and the medication group was increased (P<0.05), while the levels of Lac, K⁺ and the water content of brain tissue were decreased (P<0.05); the level of Na⁺ in the Biantie group was increased (P<0.05). Compared with the Biantie group, the level of SaO₂ in the Biantie+inhibitor group was decreased (P<0.05), and the level of Lac and the water content of brain tissue were increased (P<0.05). In the model group, the cortical tissue cells were loose and disordered, the cortical blood vessels were dilated, and the cells were obviously swollen; the anoxic injury in the Biantie group and the medication group was lighter, and the anoxic injury in the Biantie+inhibitor group was more obvious than that in the Biantie group. Compared with the blank group, the serum PHD2 content in the model group was decreased and the HIF-1α content was increased (P<0.05), and the content of VEGF in serum and VEGF protein and mRNA expressions in brain were increased (P<0.05). Compared with the model group, the content of PHD2 in serum in the Biantie group and the medication group was increased (P<0.05), and the level of HIF-1α was decreased (P<0.05), and the content of VEGF in serum as well as VEGF protein and mRNA expressions in brain were decreased (P<0.05). Compared with the Biantie group, the serum PHD2 content in the Biantie+inhibitor group was decreased and HIF-1α level were increased (P<0.05), and the content of VEGF in serum as well as VEGF mRNA expression in brain were increased (P<0.05). CONCLUSION Biantie at "Taiyuan" (LU 9), "Neiguan" (PC 6) and "Renying" (ST 9) could regulate serum PHD2/HIF-1α to down-regulate VEGF expression, reduce brain edema and enhance anti-hypoxia ability, so as to achieve the purpose of preventing brain injury at high altitude.
Animals ; Rats ; Male ; Prolyl Hydroxylases/metabolism* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Vascular Endothelial Growth Factor A/metabolism* ; Rats, Sprague-Dawley ; Procollagen-Proline Dioxygenase/metabolism* ; Brain Injuries ; Brain/metabolism* ; RNA, Messenger ; Water

OBJECTIVE: To investigate the effect of hypoxia on hypoxia-inducible factor 1α (HIF-1α) and CD47 expression in human acute myeloid leukemia (AML) cell lines. METHODS: The CD47 expression in AML U937, HL-60, and K562 cells lines were detected by flow cytometry. U937, HL-60, and K562 cells were all divided into hypoxia-treated group and conventional oxygen group. The hypoxia-treated group was cultured with 1% O₂, while the conventional oxygen group was cultured with 20% O₂, then the cells were collected after 24 hours. Real time PCR was used to examine the mRNA changes of CD47 gene. Western blot assay was applied to detect the protein expression of HIF-1α and CD47. RESULTS: The expression of CD47 in U937, HL-60, and K562 cells was 98% (98%±0.03%), 99% (99%±0.05%), and 75% (75%±0.11%), respectively. The real time PCR showed that the mRNA expression of CD47 in U937 and HL-60 cells were up-regulated in the hypoxia-treated group (P<0.05), while in K562 cells was not (P>0.05). Western blot result showed that the protein levels of HIF-1α and CD47 of U937, HL-60, and K562 cells in the hypoxia-treated group were increased compared with the conventional oxygen group (P<0.05). CONCLUSION The hypoxia can up-regulate the expression of CD47 in acute myeloid leukemia cells, which may be related to HIF-1α.
CD47 Antigen ; Humans ; Hypoxia ; Hypoxia-Inducible Factor 1, alpha Subunit ; K562 Cells ; Leukemia, Myeloid, Acute ; Oxygen ; RNA, Messenger/metabolism*

Deep venous thrombosis (DVT) poses a major challenge to public health worldwide. Endothelial cell injury evokes inflammatory and oxidative responses that contribute to thrombus formation. Tea polyphenol (TP) in the form of epigallocatechin-3-gallate (EGCG) has anti-inflammatory and oxidative effect that may ameliorate DVT. However, the precise mechanism remains incompletely understood. The current study was designed to investigate the anti-DVT mechanism of EGCG in combination with warfarin (an oral anticoagulant). Rabbits were randomly divided into five groups. A DVT model of rats was established through ligation of the inferior vena cava (IVC) and left common iliac vein, and the animals were orally administered with EGCG, warfarin, or vehicle for seven days. In vitro studies included pretreatment of human umbilical vein endothelial cells (HUVECs) with different concentrations of EGCG for 2 h before exposure to hydrogen peroxide. Thrombus weight and length were examined. Histopathological changes were observed by hematoxylin-eosin staining. Blood samples were collected for detecting coagulation function, including thrombin and prothrombin times, activated partial thromboplastin time, and fibrinogen levels. Protein expression in thrombosed IVCs and HUVECs was evaluated by Western blot, immunohistochemical analysis, and/or immunofluorescence staining. RT-qPCR was used to determine the levels of AGTR-1 and VEGF mRNA in IVCs and HUVECs. The viability of HUVECs was examined by CCK-8 assay. Flow cytometry was performed to detect cell apoptosis and ROS generation was assessed by 2',7'-dichlorofluorescein diacetate reagent. In vitro and invivo studies showed that EGCG combined with warfarin significantly reduced thrombus weight and length, and apoptosis in HUVECs. Our findings indicated that the combination of EGCG and warfarin protects HUVECs from oxidative stress and prevents apoptosis. However, HIF-1α silencing weakened these effects, which indicated that HIF-1α may participate in DVT. Furthermore, HIF-1α silencing significantly up-regulated cell apoptosis and ROS generation, and enhanced VEGF expression and the activation of the PI3K/AKT and ERK1/2 signaling pathways. In conclusion, our results indicate that EGCG combined with warfarin modifies HIF-1α and VEGF to prevent DVT in rabbits through anti-inflammation via the PI3K/AKT and ERK1/2 signaling pathways.
Animals ; Anticoagulants/pharmacology* ; Catechin/analogs & derivatives* ; Eosine Yellowish-(YS)/pharmacology* ; Fibrinogen/pharmacology* ; Hematoxylin/pharmacology* ; Human Umbilical Vein Endothelial Cells ; Humans ; Hydrogen Peroxide/pharmacology* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; MAP Kinase Signaling System ; Phosphatidylinositol 3-Kinases/metabolism* ; Polyphenols/pharmacology* ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Messenger ; Rabbits ; Rats ; Reactive Oxygen Species/metabolism* ; Signal Transduction ; Sincalide/pharmacology* ; Tea ; Thrombin/pharmacology* ; Vascular Endothelial Growth Factor A/metabolism* ; Venous Thrombosis/pathology* ; Warfarin/pharmacology*