Reversal of sorafenib resistance in hepatocellular carcinoma: epigenetically regulated disruption of 14-3-3η/hypoxia-inducible factor-1α.
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ABSTRACT:
SUBMITTER: Qiu Y
PROVIDER: S-EPMC6642098 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The stabilisation of HIF-α is central to the transcriptional response of animals to hypoxia, regulating the expression of hundreds of genes including those involved in angiogenesis, metabolism and metastasis. HIF-α is degraded under normoxic conditions by proline hydroxylation, which allows for recognition and ubiquitination by the von-Hippel-Lindau (VHL) E3 ligase complex. The aim of our study was to investigate the posttranslational modification of HIF-1α in tumours, to assess whether there are additional mechanisms besides reduced hydroxylation leading to stability. To this end we optimised antibodies against the proline-hydroxylated forms of HIF-1α for use in formalin fixed paraffin embedded (FFPE) immunohistochemistry to assess effects in tumour cells in vivo. We found that HIF-1α proline-hydroxylated at both VHL binding sites (Pro402 and Pro564), was present in hypoxic regions of a wide range of tumours, tumour xenografts and in moderately hypoxic cells in vitro. Staining for hydroxylated HIF-1α can identify a subset of breast cancer patients with poorer prognosis and may be a better marker than total HIF-1α levels. The expression of unhydroxylated HIF-1α positively correlates with VHL in breast cancer suggesting that VHL may be rate-limiting for HIF degradation. Our conclusions are that the degradation of proline-hydroxylated HIF-1α may be rate-limited in tumours and therefore provides new insights into mechanisms of HIF upregulation. Persistence of proline-hydroxylated HIF-1α in perinecrotic areas suggests there is adequate oxygen to support prolyl hydroxylase domain (PHD) activity and proline-hydroxylated HIF-1α may be the predominant form associated with the poorer prognosis that higher levels of HIF-1α confer.
| S-EPMC3923075 | biostudies-literature
Project description:Sorafenib, a multikinase inhibitor with antiproliferative, antiangiogenic, and proapoptotic properties, constitutes the only effective first-line drug approved for the treatment of advanced hepatocellular carcinoma (HCC). Despite its capacity to increase survival in HCC patients, its success is quite low in the long term owing to the development of resistant cells through several mechanisms. Among these mechanisms, the antiangiogenic effects of sustained sorafenib treatment induce a reduction of microvessel density, promoting intratumoral hypoxia and hypoxia-inducible factors (HIFs)-mediated cellular responses that favor the selection of resistant cells adapted to the hypoxic microenvironment. Clinical data have demonstrated that overexpressed HIF-1? and HIF-2? in HCC patients are reliable markers of a poor prognosis. Thus, the combination of current sorafenib treatment with gene therapy or inhibitors against HIFs have been documented as promising approaches to overcome sorafenib resistance both in vitro and in vivo. Because the depletion of one HIF-? subunit elevates the expression of the other HIF-? isoform through a compensatory loop, targeting both HIF-1? and HIF-2? would be a more interesting strategy than therapies that discriminate among HIF-? isoforms. In conclusion, there is a marked correlation between the hypoxic microenvironment and sorafenib resistance, suggesting that targeting HIFs is a promising way to increase the efficiency of treatment.
| S-EPMC6185986 | biostudies-literature
Project description:Mesenchymal stem cells (MSCs) are ideal materials for cell therapy. Research has indicated that hypoxia benefits MSC survival, but little is known about the underlying mechanism. This study aims to uncover potential mechanisms involving hypoxia inducible factor 1α (HIF1A) to explain the promoted MSC survival under hypoxia. MSCs were obtained from Sprague-Dawley rats and cultured under normoxia or hypoxia condition. The overexpression vector or small interfering RNA of Hif1a gene was transfected to MSCs, after which cell viability, apoptosis and expression of HIF1A were analyzed by MTT assay, flow cytometry, qRT-PCR and Western blot. Factors in p53 pathway were detected to reveal the related mechanisms. Results showed that hypoxia elevated MSCs viability and up-regulated HIF1A (P < 0.05) as previously reported. HIF1A overexpression promoted viability (P < 0.01) and suppressed apoptosis (P < 0.001) under normoxia. Correspondingly, HIF1A knockdown inhibited viability (P < 0.05) and promoted apoptosis (P < 0.01) of MSCs under hypoxia. Expression analysis suggested that p53, phosphate-p53 and p21 were repressed by HIF1A overexpression and promoted by HIF1A knockdown, and B-cell CLL/lymphoma 2 (BCL2) expression had the opposite pattern (P < 0.05). These results suggest that HIF1A may improve viability and suppress apoptosis of MSCs, implying the protective effect of HIF1A on MSC survival under hypoxia. The underlying mechanisms may involve the HIF1A-suppressed p53 pathway. This study helps to explain the mechanism of MSC survival under hypoxia, and facilitates the application of MSCs in cell therapy.
| S-EPMC5376042 | biostudies-literature
Project description:Cyst expansion in polycystic kidney disease (PKD) results in localized hypoxia in the kidney that may activate hypoxia-inducible factor-1α (HIF-1α). HIF-1α and autophagy, a form of programmed cell repair, are induced by hypoxia. The purposes were to determine HIF-1α expression and autophagy in rat and mouse models of PKD. HIF-1α was detected by electrochemiluminescence. Autophagy was visualized by electron microscopy (EM). LC3 and beclin-1, markers of autophagy, were detected by immunoblotting. Eight-week-old male heterozygous (Cy/+) and 4-wk-old homozygous (Cy/Cy) Han:SPRD rats, 4-wk-old cpk mice, and 112-day-old Pkd2WS25/- mice with a mutation in the Pkd2 gene were studied. HIF-1α was significantly increased in massive Cy/Cy and cpk kidneys and not smaller Cy/+ and Pkd2WS25/- kidneys. On EM, features of autophagy were seen in wild-type (+/+), Cy/+, and cpk kidneys: autophagosomes, mitophagy, and autolysosomes. Specifically, autophagosomes were found on EM in the tubular cells lining the cysts in cpk mice. The increase in LC3-II, a marker of autophagosome production and beclin, a regulator of autophagy, in Cy/Cy and cpk kidneys, followed the same pattern of increase as HIF-1α. To determine the role of HIF-1α in cyst formation and/or growth, Cy/+ rats, Cy/Cy rats, and cpk mice were treated with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). 2ME2 had no significant effect on kidney volume or cyst volume density. In summary, HIF-1α is highly expressed in the late stages of PKD and is associated with an increase in LC3-II and beclin-1. The first demonstration of autophagosomes in PKD kidneys is reported. Inhibition of HIF-1α did not have a therapeutic effect.
| S-EPMC3094047 | biostudies-literature
Project description:The receptor-tyrosine kinase ErbB4 was identified as a direct regulator of hypoxia-inducible factor-1α (HIF-1α) signaling. Cleaved intracellular domain of ErbB4 directly interacted with HIF-1α in the nucleus, and stabilized HIF-1α protein in both normoxic and hypoxic conditions by blocking its proteasomal degradation. The mechanism of HIF stabilization was independent of VHL and proline hydroxylation but dependent on RACK1. ErbB4 activity was necessary for efficient HRE-driven promoter activity, transcription of known HIF-1α target genes, and survival of mammary carcinoma cells in vitro. In addition, mammary epithelial specific targeting of Erbb4 in the mouse significantly reduced the amount of HIF-1α protein in vivo. ERBB4 expression also correlated with the expression of HIF-regulated genes in a series of 4552 human normal and cancer tissue samples. These data demonstrate that soluble ErbB4 intracellular domain promotes HIF-1α stability and signaling via a novel mechanism.
| S-EPMC3322979 | biostudies-literature
Project description:BackgroundThe identification of novel targets for recovering sorafenib resistance is pivotal for Hepatocellular carcinoma (HCC) patients. Mitophagy is the programmed degradation of mitochondria, and is likely involved in drug resistance of cancer cells. Here, we identified hyperactivated mitophagy is essential for sorafenib resistance, and the mitophagy core regulator gene ATAD3A (ATPase family AAA domain containing 3A) was down regulated in hypoxia induced resistant HCC cells. Blocking mitophagy may restore the sorafenib sensitivity of these cells and provide a new treatment strategy for HCC patients.MethodsHypoxia induced sorafenib resistant cancer cells were established by culturing under 1% O2 with increasing drug treatment. RNA sequencing was conducted in transfecting LM3 cells with sh-ATAD3A lentivirus. Subsequent mechanistic studies were performed in HCC cell lines by manipulating ATAD3A expression isogenically where we evaluated drug sensitivity, molecular signaling events. In vivo study, we investigated the combined treatment effect of sorafenib and miR-210-5P antagomir.ResultsWe found a hyperactivated mitophagy regulating by ATAD3A-PINK1/PARKIN axis in hypoxia induced sorafenib resistant HCC cells. Gain- and loss- of ATAD3A were related to hypoxia-induced mitophagy and sorafenib resistance. In addition, ATAD3A is a functional target of miR-210-5p and its oncogenic functions are likely mediated by increased miR-210-5P expression. miR-210-5P was upregulated under hypoxia and participated in regulating sorafenib resistance. In vivo xenograft assay showed that miR-210-5P antagomir combined with sorafenib abrogated the tumorigenic effect of ATAD3A down-regulation in mice.ConclusionsLoss of ATAD3A hyperactivates mitophagy which is a core event in hypoxia induced sorafenib resistance in HCC cells. Targeting miR-210-5P-ATAD3A axis is a novel therapeutic target for sorafenib-resistant HCC.
| S-EPMC7720487 | biostudies-literature
Project description:Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular smooth muscle cells, the reorganization of extracellular matrix components, the elimination of dead cells, and the restoration of normal blood flow. However, chronic sterile inflammation within the arterial walls draws inflammatory macrophages into intimal/neointimal regions that may contribute to disease pathogenesis. In this context, the accumulation and aberrant activation of macrophages in the neointimal regions govern the progression of inflammatory arterial wall diseases. Herein, we report that myeloid-hypoxia-inducible factor-1α (HIF1α) deficiency attenuates vascular smooth muscle cells and macrophage abundance in stenotic arteries and abrogates carotid neointima formation in vivo. The integrated transcriptomics, Gene Set Enrichment Analysis, metabolomics, and target gene evaluation showed that HIF1α represses oxidative phosphorylation, tricarboxylic acid cycle, fatty acid metabolism, and c-MYC signaling pathways while promoting inflammatory, glycolytic, hypoxia response gene expression in stenotic artery macrophages. At the molecular level, proinflammatory agents utilized STAT3 signaling pathways to elevate HIF1α expression in macrophages. Collectively, this study uncovers that macrophage-HIF1α deficiency restrains the pathogenesis of carotid artery stenosis by rewiring inflammatory and metabolic signaling pathways in macrophages.
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Project description:Hypoxia-inducible factors (HIF) belong to the basic helix loop helix-PER ARNT SIM (bHLH-PAS) family of transcription factors that induce metabolic reprogramming under hypoxic condition. The phylogenetic studies of hypoxia-inducible factor-1α (HIF-1α) sequences across different organisms/species may leave a clue on the evolutionary relationships and its probable correlation to tumorigenesis and adaptation to low oxygen environments. In this study, we have aimed at the evolutionary investigation of the protein HIF-1α across different species to decipher their sequence variations/mutations and look into the probable causes and abnormal behaviour of this molecule under exotic conditions. In total, 16 homologous sequences for HIF-1α were retrieved from the National Center for Biotechnology Information. Sequence identity was performed using the Needle program. Multiple aligned sequences were used to construct the phylogeny using the neighbour-joining method. Most of the changes were observed in oxygen-dependent degradation domain and inhibitory domain. Sixteen sequences were clustered into 5 groups. The phylogenetic analysis clearly highlighted the variations that were observed at the sequence level. Comparisons of the HIF-1α sequence among cancer-prone and cancer-resistant animals enable us to find out the probable clues towards potential risk factors in the development of cancer.
| S-EPMC5460953 | biostudies-literature
Project description:Hypoxia-inducible factor (HIF) is a transcription factor that facilitates cellular adaptation to hypoxia and ischemia. Long-standing evidence suggests that one isotype of HIF, HIF-1α, is involved in the pathogenesis of various solid tumors and cardiac diseases. However, the role of HIF-1α in retina remains poorly understood. HIF-1α has been recognized as neuroprotective in cerebral ischemia in the past two decades. Additionally, an increasing number of studies has shown that HIF-1α and its target genes contribute to retinal neuroprotection. This review will focus on recent advances in the studies of HIF-1α and its target genes that contribute to retinal neuroprotection. A thorough understanding of the function of HIF-1α and its target genes may lead to identification of novel therapeutic targets for treating degenerative retinal diseases including glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal vein occlusions.
| S-EPMC5326762 | biostudies-literature
Project description:Around birth, globin expression in human red blood cells (RBCs) shifts from γ-globin to β-globin, which results in fetal haemoglobin (HbF, α2γ2) being gradually replaced by adult haemoglobin (HbA, α2β2)1. This process has motivated the development of innovative approaches to treat sickle cell disease and β-thalassaemia by increasing HbF levels in postnatal RBCs2. Here we provide therapeutically relevant insights into globin gene switching obtained through a CRISPR-Cas9 screen for ubiquitin-proteasome components that regulate HbF expression. In RBC precursors, depletion of the von Hippel-Lindau (VHL) E3 ubiquitin ligase stabilized its ubiquitination target, hypoxia-inducible factor 1α (HIF1α)3,4, to induce γ-globin gene transcription. Mechanistically, HIF1α-HIF1β heterodimers bound cognate DNA elements in BGLT3, a long noncoding RNA gene located 2.7 kb downstream of the tandem γ-globin genes HBG1 and HBG2. This was followed by the recruitment of transcriptional activators, chromatin opening and increased long-range interactions between the γ-globin genes and their upstream enhancer. Similar induction of HbF occurred with hypoxia or with inhibition of prolyl hydroxylase domain enzymes that target HIF1α for ubiquitination by the VHL E3 ubiquitin ligase. Our findings link globin gene regulation with canonical hypoxia adaptation, provide a mechanism for HbF induction during stress erythropoiesis and suggest a new therapeutic approach for β-haemoglobinopathies.
| S-EPMC9773321 | biostudies-literature