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At least 19 recordsLinked to original sources

Genome-wide CRISPR screen identifies a cytokine-enhancer circuit driving HIF-2α activation in renal cancer.

Resistance to HIF-2α inhibitors such as belzutifan underscores the need to better understand how HIF-2α is transcriptionally regulated in clear cell renal cell carcinoma (ccRCC). Here, we uncover a cytokine-driven enhancer mechanism that sustains HIF-2α expression through the JAK1/STAT3 signaling pathway. Using a genome-wide CRISPR screen in von Hippel-Lindau-deficient (VHL-deficient) ccRCC cells, we identified SOCS3 as a key negative regulator of HIF-2α. Mechanistically, loss of SOCS3 activates JAK1/STAT3 signaling, leading to the recruitment of STAT3 to distal enhancers upstream of endothelial PAS domain-containing protein (EPAS1) that physically loop to its promoter to drive HIF-2α transcription. This cytokine-enhancer circuit was recapitulated in samples from patients with ccRCC and functionally validated using CRISPR interference (CRISPRi), which disrupted enhancer-promoter looping and reduced tumor growth in HIF-2α-dependent models. SOCS3 overexpression or pharmacologic inhibition of JAK1/STAT3 markedly suppressed HIF-2α expression and tumor progression both in vitro and in vivo. Unlike prior studies focusing on VHL/HIF occupancy-driven enhancer activation, this work defines a trans-acting cytokine-JAK1/STAT3 pathway that transcriptionally controls EPAS1. Together, these findings reveal a targetable enhancer mechanism that sustains HIF-2α expression and suggest that combined inhibition of JAK1/STAT3 and HIF-2α may overcome therapeutic resistance in kidney cancer.

Basic Helix-Loop-Helix Proteins

Hepatocyte growth factor-activated NF-kappaB regulates HIF-1 activity and ODC expression, implicated in survival, differently in different carcinoma cell lines.

Hepatocyte growth factor (HGF)-stimulated Met signaling influences tumor survival, growth and progression, all processes involving the transcription factor NF-kappaB. NF-kappaB plays a complex role in the control of survival due to the influence of cellular factors acting downstream. We undertook a comparative investigation of two human breast carcinoma cells with different grades of malignancy and HepG2 hepatoma cells, which present a biphasic response to HGF (proliferation followed by apoptosis). We found evidence that HGF induced gene patterns characteristic of survival rather than apoptosis depending on the cell type. The ability of NF-kappaB to regulate expression of hypoxia-inducible factor-1alpha (HIF-1alpha), a survival/anti-apoptotic gene in cancer, seemed to be critical. In the HepG2 and MCF-7 (low invasive breast carcinoma) cell lines increased transcription and translation were responsible for HIF-1alpha induction after HGF. The regulation by NF-kappaB was mainly at the level of the 5'-UTR of the HIF-1alpha message. HIF-1 (alpha/beta heterodimer) was likely to transactivate Mcl-1, another anti-apoptotic gene. Opposite results were observed in MDA-MB-231 cells (highly invasive breast carcinoma), which have high NF-kappaB activity, further inducible by HGF, because HIF-1alpha mRNA expression and HIF-1 transactivating capacity were HGF-insensitive while the alpha subunit seemed to be degraded after HGF. However, ornithine decarboxylase (ODC) and heme oxygenase mRNA expression persistently increased. By transiently transfecting two ODC gene reporters we demonstrated that ODC is a target gene of NF-kappaB in HGF-treated tumor cells. By regulating HIF-1 activity and specific gene expression downstream, NF-kappaB may influence the survival threshold, with an impact on the fate of carcinoma cells after prolonged HGF treatment.

Breast Neoplasms

HIF-1 signaling contributes to lenvatinib resistance in patient-derived HCC organoids.

Resistance to lenvatinib remains an important limitation in hepatocellular carcinoma treatment. Six patient-derived organoid lines were established and classified as sensitive or resistant according to ex vivo drug responses, retaining histological and immunophenotypic features of matched parental tumors. Resistant organoids showed unchanged ATP activity, whereas sensitive ones exhibited pronounced morphological changes and reduced ATP activity at higher concentrations. Transcriptome sequencing identified 408 upregulated and 269 downregulated genes in resistant versus sensitive organoids, with HIF-1 signaling among altered pathways. In resistant organoids, lenvatinib increased HIF-1α, ANGPT2, and HK3 mRNA, whereas comparable changes were not detected in sensitive organoids. KC7F2 reduced these transcripts and further decreased ATP activity when combined with lenvatinib. In organoid-derived xenografts, this combination suppressed tumor growth and HIF-1 target expression more than lenvatinib alone, indicating HIF-1 signaling contributes to the resistant phenotype and its inhibition may enhance response.

Drug resistance

[The effect of human leukocyte interteron (HIF) on experimental viral keratitis in monkeys (author's transl)].

12 african green monkeys were inoculated in both eyes with herpes simplex virus typ 1 and 16 rhesus monkeys with vaccinia virus. The right eyes were treated with human leukocyte interferon (HIF) while the left eyes served as controls and showed the typical keratitis, 7 out of 8 herpes eyes and all 9 vaccinia eyes which were treated prophylactically or simultaneiously with HIF showed no signs of disease. When HIF was given later in the course of the infection the keratitis was either little influenced or not modified at all. The reasons are discussed.

Animals

Enhanced HIF-1α cooperation by a human RORγt mutant potentiates Th17 pathogenicity.

T helper 17 (Th17) cells are pivotal in mucosal defense and autoimmune pathology, with their function governed by the transcription factor retinoic acid receptor-related orphan receptor gamma t (RORγt). Although genome-wide association studies link RORC variants to inflammatory diseases, their functional consequences remain poorly understood. We identify a pathogenic RORγt mutation N277D (mouse homolog N275D) that amplifies Th17 pathogenicity through cooperation with hypoxia-inducible factor HIF-1α. This mutation enhances IFN-γ and other Th1-type cytokine production by Th17 cells, exacerbating colitis without disrupting T cell development or homeostasis. Integrated transcriptomic and metabolomic profiling reveals activation of glycolytic and hypoxia-associated pathways, consistent with increased RORγtN275D recruitment by HIF-1α to the Pdk1 locus. Notably, silencing Pdk1 normalizes the excessive IFN-γ production in RORγtN275D Th17 cells. Together, these findings define a regulatory axis linking RORγt and HIF-1α that coordinates transcriptional and metabolic programs in pathogenic Th17 cells, providing a framework for dissecting the functional impact of autoimmune risk variants.

CP: immunology

The Triad of NF-κB, HIF-1α, and Oxidative Stress in Hepatocellular Carcinoma: Pathogenesis, Clinical Challenges, and Therapeutic Potential of CIGB-552 in Liver Transplantation.

Hepatocellular carcinoma (HCC) represents a formidable oncological challenge characterized by complex molecular pathogenesis and limited therapeutic outcomes, particularly in the context of liver transplantation. As the sixth most commonly diagnosed cancer and the third leading cause of cancer-related mortality worldwide, HCC poses significant clinical challenges that demand innovative therapeutic approaches. Central to HCC development and progression is a pathogenic triad comprising nuclear factor-kappa B (NF-κB), hypoxia-inducible factor-1α (HIF-1α), and oxidative stress-three interconnected pathways that drive inflammation, angiogenesis, metabolic reprogramming, and cell survival. This comprehensive review examines the molecular mechanisms underlying this triad in HCC pathogenesis across different etiological contexts, including viral hepatitis and non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH). We critically analyse the unique clinical challenges posed by HCC in liver transplantation recipients, particularly the paradoxical requirement for immunosuppression alongside antitumor immunity, and constraints surrounding immunotherapy application. Furthermore, we present CIGB-552, a novel peptide therapeutic targeting COMMD1 (Copper Metabolism MURR1 Domain-containing protein 1), as a promising dual-function agent capable of simultaneously disrupting the pathogenic triad through NF-κB inhibition, HIF-1α suppression, and strategic modulation of oxidative stress via SOD1 regulation. The multimodal mechanism of CIGB-552 offers a theoretically rational therapeutic approach for HCC management in both pre-transplant and post-transplant settings. Clinical validation in the transplantation setting is required.

Humans

Studies on the effects of the pineal hormone melatonin on an androgen-insensitive rat prostatic adenocarcinoma, the Dunning R 3327 HIF tumor.

The effects of the pineal indole melatonin on a transplantable androgen-insensitive fast-growing rat prostatic adenocarcinoma, the Dunning R 3327 HIF tumor, were examined. Afternoon injections of melatonin given to intact male rats enhanced tumor growth, while leading to a reduction in the weights of gonads and dorsal and ventral prostates. In anosmic hosts, this treatment had no effect on tumor growth or reproductive organ size. In castrated anosmic hosts, melatonin injections led to reductions in the growth of tumors, when compared with those in castrated hosts. Continuously available melatonin, in beeswax pellets, had no effect on growth of these tumors. These results are discussed in relation to the anticancer effects of melatonin and the effects of tumors on endogenous melatonin rhythms.

Adenocarcinoma

Hypoxia-inducible factor-1α promotes the malignant progression of cervical cancer cells by regulating lactate dehydrogenase A-mediated glycolysis.

BACKGROUND: Enhanced glycolysis is a hallmark of metabolic reprogramming in cervical cancer and plays a key role in tumor progression. Hypoxia-inducible factor-1α (HIF-1α), a core regulator of glycolytic metabolism, remains incompletely characterized in cervical cancer. This study aimed to investigate the expression pattern and clinical significance of HIF-1α in cervical cancer, and to explore its association with malignant biological behavior and lactate dehydrogenase A (LDHA)-related glycolytic metabolism in cervical cancer cells. METHODS: The expression level, clinicopathological features, immune infiltration correlation, and prognostic value of HIF-1α in cervical cancer were analyzed based on the The Cancer Genome Atlas (TCGA) database. HIF-1α overexpression and knockdown models were established in HeLa and Caski cells. Cell viability and invasive ability were assessed by Cell Counting Kit-8 (CCK-8) and Transwell assays, respectively. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect changes in LDHA expression. Lactate production was measured using a lactate assay kit, and intracellular reactive oxygen species (ROS) levels were determined by flow cytometry. RESULTS: Bioinformatics analysis showed that HIF-1α was highly expressed in cervical cancer and was closely associated with patient age, menopausal status, immune cell infiltration, and poor prognosis. Kaplan-Meier survival analysis demonstrated that patients with high HIF-1α expression had significantly worse overall survival (OS) than those with low expression. In vitro functional experiments further confirmed that HIF-1α overexpression significantly enhanced the viability and invasive ability of HeLa and Caski cells, whereas HIF-1α knockdown produced the opposite effects. HIF-1α overexpression was associated with increased messenger RNA (mRNA) and protein expression levels of LDHA, a key glycolytic molecule, along with increased lactate production and elevated intracellular ROS levels. CONCLUSIONS: HIF-1α is aberrantly highly expressed in cervical cancer and may enhance glycolytic activity by upregulating LDHA expression, thereby promoting the proliferation and invasion of cervical cancer cells. These findings suggest that HIF-1α could serve as a potential diagnostic, prognostic, and therapeutic target biomarker for cervical cancer.

Hypoxia-inducible factor-1α (HIF-1α)

Intramuscular and/or intralumbar postexposure treatment of rabies virus-infected cynomolgus monkeys with human interferon.

From 9 to 10 of 10 cynomolgus monkeys infected with rabies street virus died of rabies about 20 days postinfection (pI). Symptoms of illness appeared 1 to 4 days before death. In an attempt to protect infected animals from the disease, human leukocyte interferon (HIF) was administered intramuscularly (i.m.) near the site of infection or into the cerebrospinal fluid between the first and second lumbar vertebrae (i.e., intralumbarly [i.l.]). Multiple HIF doses given over a period of several days proved more effective than a single HIF dose. In every experiment, i.m. HIF treatment was started 1 day pI. The best result obtained was a survival rate of 7 of 10 monkeys. The i.l. HIF administration schedules, consisting of multiple doses given over a period of at least 8 days, were started on day 3, 7, or 11 pI. Here the best result noted was the protection of 5 of 10 treated monkeys. The latest successful postexposure i.l. HIF treatment began on day 11 pI. The highest protection rate, 8 survivors of 10 treated monkeys, was achieved by a combined i.m. and i.l. HIF treatment. From these results we conclude that human patients severely bitten by rabid animals should in addition to an active immunization be i.m. and i.l. treated with HIF. Particularly, i.l. HIF administration could be effective, even when given several days pI. Whether an HIF administration starting after the appearance of clinical symptoms of rabies can help cannot be decided upon from the studies made in this monkey model. The most obvious difference between rabies in humans and cynomolgus monkeys is the duration of illness between the outbreak of the disease and death (1 to 4 days only in this animal model). It might have been due to this short period of illness that i.l. and i.m. HIF treatment at the appearance of clinical symptoms failed to help any of the monkeys treated.

Animals

Hypothalamic factor inhibits the (Na,K)ATPase from the extracellular surface. Mechanism of inhibition.

We have characterized the effect of a stable small molecule isolated from bovine hypothalamus (Haupert, G. T., and Sancho, J. M. (1979) Proc. Natl. Acad. Sci. 76, 4658-4660) on mammalian (Na,K)ATPase. This hypothalamus-derived inhibitory factor, HIF, has been shown to inhibit ATPase activity of purified dog kidney enzyme reversibly with high affinity (Haupert, G. T., Carilli, C. T., and Cantley, L. C. (1984) Am. J. Physiol. 247, F919-F924). In this report it is shown that HIF inhibits the ouabain sensitive component of 86Rb+ uptake into human red blood cells. HIF also inhibited (Na,K)ATPase activity of unsealed red cell membranes but not that of sealed inside-out vesicles, indicating that HIF is impermeant to red cell membranes and inhibits the (Na,K)ATPase from the extracellular side. In unsealed human red cell membranes, concentrations of HIF which caused 70% inhibition of the (Na,K)ATPase did not inhibit ATP hydrolysis by plasma membrane (Ca2+)ATPase or (Mg2+)ATPase. However, at a similar concentration, HIF was shown to inhibit rabbit muscle sarcoplasmic reticulum (Ca2+)ATPase. HIF also inhibited p-nitrophenylphosphatase activity of unmodified or fluorescein-5'-iso-thiocyanate labeled dog kidney (Na,K)ATPase. As judged by fluorescein fluorescence of the modified enzyme, HIF stabilized the low fluorescent "E2" conformation of the enzyme similar to that stabilized by ouabain. However, unlike ouabain, HIF blocked covalent phosphorylation of dog kidney (Na,K)ATPase by inorganic phosphate. These studies show that HIF is an inhibitor of (Na,K)ATPase which acts from the extracellular side of the membrane by a mechanism similar to but not identical to that of cardiac glycosides.

4-Nitrophenylphosphatase

Genetic analysis of pathways regulated by the von Hippel-Lindau tumor suppressor in Caenorhabditis elegans.

The von Hippel-Lindau (VHL) tumor suppressor functions as a ubiquitin ligase that mediates proteolytic inactivation of hydroxylated alpha subunits of hypoxia-inducible factor (HIF). Although studies of VHL-defective renal carcinoma cells suggest the existence of other VHL tumor suppressor pathways, dysregulation of the HIF transcriptional cascade has extensive effects that make it difficult to distinguish whether, and to what extent, observed abnormalities in these cells represent effects on pathways that are distinct from HIF. Here, we report on a genetic analysis of HIF-dependent and -independent effects of VHL inactivation by studying gene expression patterns in Caenorhabditis elegans. We show tight conservation of the HIF-1/VHL-1/EGL-9 hydroxylase pathway. However, persisting differential gene expression in hif-1 versus hif-1; vhl-1 double mutant worms clearly distinguished HIF-1-independent effects of VHL-1 inactivation. Genomic clustering, predicted functional similarities, and a common pattern of dysregulation in both vhl-1 worms and a set of mutants (dpy-18, let-268, gon-1, mig-17, and unc-6), with different defects in extracellular matrix formation, suggest that dysregulation of these genes reflects a discrete HIF-1-independent function of VHL-1 that is connected with extracellular matrix function.

Animals

Effect of human leukocyte interferon on vaccinia-and herpes virus-infected cell cultures and monkey corneas.

Pretreatment of human fibroblast cultures with human leukocyte interferon (HIF, 1,000 IU/ml) resulted in a 24-h delay of virus replication after infection with vaccinia virus and herpes simplex virus type 1 and type 2. Additional HIF treatment 24 h after infection effectively lowered the maximum yield of viral infectivity. Equal results were obtained in simian cells with 3,000 IU of HIF per ml. The spread of two cell-bound herpesviruses, varicella zoster virus and Medical Lake macaque herpesvirus, was inhibited by 2,000 IU of HIF per ml in human fibroblasts and Vero cells, respectively. Varicella zoster virus infectivity was notably reduced by HIF, whereas the latter system showed a low sensitivity. To study the effect of HIF in the infected cornea, keratitis was induced experimentally in both eyes of 12 rhesus monkeys and 12 African green monkeys by inoculation with vaccinia virus and herpes simplex virus, respectively. In each monkey one eye served as a control for the full cycle of disease. In the other eye HIF treatment was initiated prophylactically 15 h before or simultaneously with the challenge virus infection or 6 to 20 h postinfectionally or therapeutically after onset of the disease, and the treatment was continued for 2 to 7 days. Prophylactic and simultaneous administration equally resulted in inhibition of both vaccinia and herpes keratitis. Postinfectional and therapeutic administration of interferon moderated the course of keratitis slightly and shortened the period of virus shedding.

Animals

Hypothalamic Na(+)-K(+)-ATPase inhibitor characterized in two-sided liposomes containing pure renal Na(+)-K(+)-ATPase.

The functional characterization of putative endogenous inhibitors of the Na(+)-K(+)-ATPase has been greatly hindered by spare amounts extractable from biological sources. We therefore used a miniaturized, two-sided test system consisting of ATP-filled liposomes containing dispersed, randomly oriented renal Na(+)-K(+)-ATPase molecules to study effects of a low-molecular-weight, nonpeptidic Na(+)-K(+)-ATPase inhibitor extracted from bovine hypothalamus. With this test system, Na(+)-K(+)-ATPase inhibition produced by a single dose of 0.1 U (congruent to 75 fmol) of the hypothalamic inhibitory factor (HIF) as well as the membrane permeation of a single unit (approximately equal to 750 fmol) became measurable, and an estimation of the minimal number of HIF molecules per unit could be made. By a molecular mechanism involving positive cooperativity, HIF potently and completely blocked active 86Rb+ transport catalyzed by the right-side-out-oriented pump population, with an average 50% inhibitory concentration of 3.5 x 10(-8) M, indicating a roughly 30-fold higher apparent affinity than ouabain. By studying inhibition of the inside-out-oriented pump population, comparison of the membrane permeability of HIF to that of various cardiac glycosides of known hydrophobicity further indicated that HIF is not entirely ouabain-like as HIF penetrates the liposomal membrane, whereas ouabain does not. Besides the cardiac glycosides, HIF is the only compound tested thus far in the purified system that displays such striking transport inhibition. Other known or proposed endogenous Na(+)-K(+)-ATPase inhibitors, including unsaturated fatty acids, palytoxin, dehydroepiandrosterone, and vanadate, produce only partial transport inhibition even at high concentration.

Animals

[Sensitivity of various primate cells and animal viruses to the antiviral activity of human leukocyte interferon (author's transl)].

U cells (a permanent, human amnion cell line) were protected against infection with Semliki Forest Virus (SFV) by human interferon (HIF) from peripheral leukocytes. Despite the usual genus-specific action of interferons, mouse L929 cultures (a permanent mouse fibroblast cell line) were also protected by HIF. The antiviral action of HIF in six other primate cell cultures was also examined. It is of interest that two lymphoblastoid cell lines, RPMI1788 and Kaplan, were insensitive to HIF. The sensitivity of ten different viruses against HIF in primary African green monkey kidney cell cultures was compared. Among the viruses tested SFV was the most sensitive whereas two strains of vaccinia virus were barely inhibited. In contrast, type 1 herpes simplex virus was relatively sensitive to the action of HIF.

Amnion

In vitro activity of alpha, beta, gamma human interferons and Aspergillus terreus mycotoxins on cell proliferation.

The in vitro effect of different doses of alpha, beta and gamma human interferons and their interaction on the proliferation rate of human erythroleukemic cell line (K-562) and other cell lines has been evaluated. The results show that the stronger activity is exerted by beta HIF in comparison with alpha HIF. The action is selective and species-specific. beta HIF never elicited an "enhancing" effect on cell proliferation; on the contrary this phenomenon has been observed to occur with alpha and gamma HIF. In our cell system, the interaction between beta and gamma HIF gave a synergistic effect; on the contrary, no interaction has been observed to take place when beta HIF and directly cytotoxic mycotoxins extracted from A. terreus are associated.

Cell Division