HIF-1α serves as a co-linker between AD and T2DM

Alzheimer's disease (AD)-related brain deterioration is linked to the type 2 diabetes mellitus (T2DM) features hyperglycemia, hyperinsulinemia, and insulin resistance. Hypoxia as a common risk factor for both AD and T2DM. Hypoxia-inducible factor-1 alpha (HIF-1α) acts as the main regulator of the hypoxia response and may be a key target in the comorbidity of AD and T2DM. HIF-1α expression is closely related to hyperglycemia, insulin resistance, and inflammation. Tissue oxygen consumption disrupts HIF-1α homeostasis, leading to increased reactive oxygen species levels and the inhibition of insulin receptor pathway activity, causing neuroinflammation, insulin resistance, abnormal Aβ deposition, and tau hyperphosphorylation. HIF-1α activation also leads to the deposition of Aβ by promoting the abnormal shearing of amyloid precursor protein and inhibiting the degradation of Aβ, and it promotes tau hyperphosphorylation by activating oxidative stress and the activation of astrocytes, which further exasperates AD. Therefore, we believe that HIF-α has great potential as a target for the treatment of AD. Importantly, the intracellular homeostasis of HIF-1α is a more crucial factor than its expression level.

Histopathological growth pattern evolution of tumor in VX2 liver cancer model

The histopathological growth pattern (HGP) is a morphological reflection of interactions between cancer cells and the surrounding tissue, and has been identified with a remarkably predictive value in liver metastases. However, there is still a lack of studies on HGP of primary liver cancer even furtherly on HGP evolution. We employed VX2 tumor-bearing rabbits as the primary liver cancer model of which tumor size and distant metastasis were investigated. HGP assessment and computed tomography scanning was performed in four cohorts of different time points to map the HGP evolution. Additionally, Fibrin deposition and neovascularization were evaluated by Masson staining and immunohistochemical analysis of CD31, hypoxia-inducible factor-1 alpha (HIF1A) and vascular endothelial growth factor (VEGF). Tumors displayed exponential growth in the VX2 liver cancer model, but these tumor-bearing animals did not show any visible metastasis until they reached a specific stage of development. Correspondingly, the components of HGPs changed along with the tumor growth. The proportion of desmoplastic HGP (dHGP) decreased initially and then grew, but in contrast, the level of replacement HGP (rHGP) rose from the 7th day, reached a peak at around the 21st day, and then appeared drop. Importantly, the collagen deposition and expression of HIF1A and VEGF correlated with dHGP, while CD31 did not. HGP evolution presents a two-way switch including dHGP to rHGP and rHGP to dHGP, in which the emergence of rHGP may be linked to metastases. HIF1A-VEGF partially participates in the HGP evolution and presumably plays a key role in the formation of dHGP.

Tumor-intrinsic FABP5 is a novel driver for colon cancer cell growth via the HIF-1 signaling pathway

Dysfunctional lipid metabolism is a known cause of cancer development and progression, yet little is known about the underlying molecular mechanisms that contribute to cancer progression. In this study, we demonstrate that fatty acid binding protein 5 (FABP5) is elevated in colon cancer tissue and this increased expression is linked to upregulation of the hypoxia-inducible factor-1 (HIF-1) signaling pathway. Under physiologically in vivo mimicked conditions via a polydimethylsiloxane (PDMS)-based three-dimensional (3D) culture chip, FABP5-knockdown colon cancer cells exhibited attenuated cell growth throughout the culture period. FABP5 was found to regulate HIF-1α protein levels and gene expression levels within the HIF-1α signaling pathway under hypoxic conditions. Our results provide evidence that supports the use of FABP5 as a prognostic factor in colon cancer. The FABP5/HIF-1α axis is a promising target for ameliorating fatty acid-triggered cancer progression.

HIF-1α/JMJD1A signaling regulates inflammation and oxidative stress following hyperglycemia and hypoxia-induced vascular cell injury

Background

Endothelial cell (EC) injury accelerates the progression of diabetic macrovascular complications. Hypoxia is an important cause of EC injury. Hypoxia-inducible factor-1 alpha (HIF-1α) is an important hypoxia regulatory protein. Our previous studies showed that high-glucose and hypoxic conditions could upregulate HIF-1α expression and enhance EC inflammatory injury, independently of the nuclear factor kappa-B (NF-κB) pathway. However, it is not clear whether HIF-1α plays a role in vascular disease through epigenetic-related mechanisms.

Methods

We conducted gene expression analysis and molecular mechanistic studies in human umbilical vein endothelial cells (HUVECs) induced by hyperglycemia and hypoxia using RNA sequencing (RNA-seq) and small interfering HIF-1α (si-HIF-1α). We determined HIF-1α and Jumonji domain-containing protein 1 A (JMJD1A) expression by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot, analyzed inflammatory protein secretion in the cell supernatant by enzymelinked immunosorbent assay (ELISA), and assessed protein interaction between HIF-1α and JMJD1A by chromatin immunoprecipitation (Ch-IP). We used the Cell Counting Kit8 (CCK-8) assay to analyze cell viability, and assessed oxidative stress indicators by using a detection kit and flow cytometry.

Results

High glucose and hypoxia up-regulated HIF-1α expression, and down-regulated HIF-1α decreased the level of inflammation and oxidative stress in HUVECs. To determine the downstream pathways, we observed histone demethylases genes and related pathway by RNA-sEq. Among these, JMJD1A was the most upregulated gene in histone demethylases. Moreover, we observed that HIF-1α bound to the promoter of JMJD1A, and the ameliorative effects of si-HIF-1α on oxidative stress and inflammatory cytokines in high-glucose and hypoxia-induced HUVECs were reversed by JMJD1A overexpression. Furthermore, knockdown of JMJD1A decreased inflammatory and oxidative stress injury. To determine the JMJD1A-related factors, we conducted gene expression analysis on JMJD1A-knockdown HUVECs. We observed that downregulation of inflammation and the oxidative stress pathway were enriched and FOS and FOSB might be important protective transcription factors.

Conclusions

These findings provide novel evidence that the HIF-1α/JMJD1A signaling pathway is involved in inflammation and oxidative stress in HUVECs induced by high glucose and hypoxia. Also, this pathway might act as a novel regulator of oxidative stress and inflammatory-related events in response to diabetic vascular injury and thus contribute to the pathological progression of diabetes and vascular disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-021-00283-8.

Acne Lesion Extraction versus Oral Doxycycline for Moderate Acne Vulgaris: A Randomized Clinical Trial

CLINICAL TRIAL ID

NCT04206631.

BACKGROUND

Acne vulgaris is a polymorphic skin condition comprising inflamed and noninflamed lesions. In addition to topical retinoids, systemic antibiotics play a role as a main therapy for acne with inflamed papules and cysts. However, due to the increasing tendency for bacterial resistance, alternatives to antibiotics are needed.

OBJECTIVE

The aim of this study was to evaluate the effectiveness of acne lesion extraction compared to oral doxycycline for moderate acne vulgaris and to explore the impact of both treatments on Hypoxia-inducible factor (HIF)-1 alpha.

METHODS

This randomized clinical trial was conducted in two teaching hospitals in 2016. Subjects with moderate acne vulgaris (N=140) were divided into two groups. Each subject in both groups received 0.05% tretinoin cream, applied to the entire face each night, and 2.5% benzoyl peroxide gel, applied to the acne lesions in the morning and afternoon. One group was also treated with oral doxycycline 100mg once daily and the other was treated with acne lesion extraction performed on all facial lesions every two weeks; the patients were evaluated via patient-reported self-assessment and lesion counts every two weeks for six weeks. HIF-1 alpha expression of the biopsied lessions was examined via immunohistochemistry.

RESULTS

128 subjects completed the study. Among these 128 subjects there was a prominent decrease in inflamed lesions at Week 6 in the lesion extraction group compared to the oral doxycycline group (p<0.05). HIF-1 alpha expression of the biopsied lesions was found in 7 of 9 samples taken from the oral doxycycline group, while 3 of 4 samples in the lesion extraction group were found negative.

CONCLUSION

According to our results, acne lesion extraction appeared to be more effective than oral doxycycline in treating this sample of patients with moderate acne vulgaris. Additionally, HIF-1 alpha expression appeared to be decreased after acne lesion extraction.

Systemic Succinate, Hypoxia-Inducible Factor-1 Alpha, and IL-1β Gene Expression in Autosomal Dominant Polycystic Kidney Disease with and without Hypertension

BACKGROUND AND OBJECTIVES

Cyst pressure induces renin-angiotensin-aldosterone system activation and kidney hypoxia in autosomal dominant polycystic kidney disease (ADPKD). Lipopolysaccharide-induced Toll-like receptor activation causes metabolic disturbances that are triggered by increased succinate levels and hypoxia inducible factors, which results in inflammation via IL-1β activation. Since we aimed to investigate the role of both inflammation and hypoxia in the clinical course of ADPKD, via succinate levels from sera samples, HIF-1α gene expression from whole blood and urine samples and IL-1βgene expression from whole blood were measured.

METHODS

One hundred ADPKD patients and 100 matched healthy controls were enrolled to this cross-sectional study. Twenty-four-hour ambulatory blood pressure monitoring was conducted in all participants. Blood, serum, and urine samples were taken after 12-h fasting for the measurement of biochemical parameters and succinate levels. Whole blood and urine samples were used for HIF-1α and IL-1β geneexpression by using quantitative real-time PCR.

RESULTS

There were significant differences in whole blood HIF-1α, IL-1β geneexpression, and serumsuccinate levels between the ADPKD patients and the control subjects. Whole blood HIF-1αgene expression, IL-1β geneexpression, and serumsuccinate levels were also significantly different in ADPKD patients with hypertension in comparison with normotensive ones (p < 0.05). Serum succinate levels and blood IL-1β geneexpression were increased in ADPKD patients with high levels of HIF-1α geneexpression (p = 0.018 and p = 0.029, respectively).

CONCLUSIONS

Increased age,low eGFR, and HIF-1α and IL-1β geneexpressions were also independently associated with hypertension in ADPKD patients. Inflammation and hypoxia are both relevant factors that might be associated with hypertension in ADPKD.

The correlation between HIF-1 alpha and VEGF in oral squamous cell carcinomas: Expression patterns and quantitative immunohistochemical analysis

BACKGROUND

The prognostic predict biomarkers are important in oral squamous cell carcinoma (OSCC). We investigated the expression patterns and quantitation of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) in OSCC patients. Among OSCC patients with recurrence and metastasis, the expression percentages of HIF-1α and VEGF also were analyzed.

METHODS

Thirty-eight patients (8 hyperkeratosis, 30 oral squamous cell carcinoma) were included in this study. In the follow-up period, 5 OSCC patients had metastasis and 12 OSCC patients had local recurrence. We used computer-assisted image processing to analyze immunohistochemistry (IHC). The quantitative analysis of IHC slides, including upper-layer epithelium (U) and lower-layer epithelium (L), was calculated.

RESULTS

We found homogeneous expression of VEGF in the epithelium. However, two patterns of HIF-1α expression were observed: homogeneous and heterogeneous. The highest U + L layer percentage in HIF-1α and VEF expression had significant association in tumor metastasis and recurrence (p<0.001 in HIF-1α and p<0.001 in VEGF). U + L layer HIF-1α expression percentage was >156.4%, and the survival rate was poor (p < 0.001).

CONCLUSION

HIF-1α expression was not only influenced by tumor hypoxia, it also reflected tumor cell characteristics. High concentrations of VEGF and HIF-1α may have value as prognostic markers of tumor metastasis and recurrence.

A polysaccharide from Sargassum thunbergii inhibits angiogenesis via downregulating MMP-2 activity and VEGF/HIF-1α signaling

A water-soluble polysaccharide (STPC2) was isolated from the boiling-water extract of Sargassum thunbergii, purified by CaCl2 precipitation and chromatography on DEAE-cellulose and Sephacryl S-300 column. It was found that STPC2, with a molecular weight of 57kD, was composed of fucose, xylose, galactose and glucuronic acid, in a ratio of 8.1: 3.8: 2.1: 1.0. Additionally, we found that STPC2 significantly inhibited endothelial cell migration and tube formation without toxicity. Moreover, STPC2 significantly inhibited lung cancer cell A549 migration and proliferation. It was found that STPC2 treatment suppressed MMP-2 gene expression at transcriptional level and enzymatic activity. Furthermore, STPC2 reduced the mRNA and protein expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor (HIF)-1 alpha in the endothelial cells. Taken together, our findings indicated that STPC2 was a potent bioactive polysaccharide with distinct anti-angiogenesis activity against tumor migration via down-regulation of MMP-2 activity and VEGF/HIF-1α signaling pathway.

Wortmannin influences hypoxia-inducible factor-1 alpha expression and glycolysis in esophageal carcinoma cells

AIM: To investigate the influence of phosphatidylinositol-3-kinase protein kinase B (PI3K/AKT)-HIF-1α signaling pathway on glycolysis in esophageal carcinoma cells under hypoxia.

METHODS: Esophageal carcinoma cell lines Eca109 and TE13 were cultured under hypoxia environment, and the protein, mRNA and activity levels of hypoxia inducible factor-1 alpha (HIF-1α), glucose transporter 1, hexokinase-II, phosphofructokinase 2 and lactate dehydrogenase-A were determined. Supernatant lactic acid concentrations were also detected. The PI3K/AKT signaling pathway was then inhibited with wortmannin, and the effects of hypoxia on the expression or activities of HIF-1α, associated glycolytic enzymes and lactic acid concentrations were observed. Esophageal carcinoma cells were then transfected with interference plasmid with HIF-1α-targeting siRNA to assess impact of the high expression of HIF-1α on glycolysis.

RESULTS: HIF-1α is highly expressed in the esophageal carcinoma cell lines tested, and with decreasing levels of oxygen, the expression of HIF-1α and the associated glycolytic enzymes and the extracellular lactic acid concentration were enhanced in the esophageal carcinoma cell lines Eca109 and TE13. In both normoxia and hypoxic conditions, the level of glycolytic enzymes and the secretion of lactic acid were both reduced by wortmannin. The expression and activities of glycolytic enzymes and the lactic acid concentration in cells were reduced by inhibiting HIF-1α, especially the decreasing level of glycolysis was significant under hypoxic conditions.

CONCLUSION: The PI3K/AKT pathway and HIF-1α are both involved in the process of glycolysis in esophageal cancer cells.

Regulation of fatty acid binding proteins by hypoxia inducible factors 1α and 2α in the placenta: relevance to pre-eclampsia

Pre-eclampsia is characterized by placental hypoxia and dyslipidemia. Arachidonic and docosahexanoic acids are essential maternal nutrients for fetal development. They are transported via placental trophoblast cells by membrane and cytosolic fatty acid binding proteins. Others report the expressions of these proteins which are increased in hypoxic trophoblasts. Using bioinformatics, BeWo cells, reporter assays, quantitative real-time PCR and immunoblotting we tested the hypothesis that hypoxia inducible factors 1α (HIF-1α) and/or 2α (HIF-2α) regulate the expressions of FABP1, FABP3, FABP4 and FATP2 proteins. Three hypoxia responsive elements (HRE) were identified in FABP1 which cumulatively responded strongly to HIF-1α and weakly to HIF-2α. FABP3 expression partially responded to HIF-1α. Two putative HRE were validated in FABP4 both of which responded weakly to HIF-1α and HIF-2α. FATP2 protein expression reacted positively to hypoxia. Thus, fetal essential fatty acid supply via the placenta is protected under hypoxia. It will be interesting to determine if our findings are replicated in human pre-eclamptic placenta.

Hinokitiol increases the angiogenic potential of dental pulp cells through ERK and p38MAPK activation and hypoxia-inducible factor-1α (HIF-1α) upregulation

Hinokitiol, a natural iron-chelating agent, is known to have diverse biological and pharmacological activities in various cell types. However, the effect of hinokitiol on dental pulp cells has not yet been reported. In this study, hinokitiol increases hypoxia-inducible factor-1α (HIF-1α) protein levels and vascular endothelial growth factor (VEGF) secretion in human dental pulp cells. The extracellular-signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways are involved in hinokitiol-induced HIF-1α protein expression in dental pulp cells. Conditioned media from hinokitiol-treated pulp cells enhances angiogenesis in vitro and in vivo. Overall, these results show that hinokitiol promotes ERK and p38MAPK activation and HIF-1α-induced VEGF production, thus increasing the angiogenic potential of dental pulp cells.

Hypoxia and cytokines regulate carbonic anhydrase 9 expression in hepatocellular carcinoma cells in vitro

AIM: To study the expression of carbonic anhydrase (CA) 9 in human hepatocellular carcinoma (HCC) cells.

METHODS: We studied CA9 protein, CA9 mRNA and hypoxia-inducible factor-1 alpha (HIF-1α) protein levels in Hep3B cells exposed in different parallel approaches. In one of these approaches, HCC cells were exposed to extreme in vitro hypoxia (24 h 0.1% O₂) without or with interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) stimulation for the same hypoxic exposure time or exposed to normoxic oxygenation conditions without or with cytokine stimulation.

RESULTS: The tumour cell line analysed showed a strong hypoxic CA9 mRNA expression pattern in response to prolonged severe hypoxia with cell-line specific patterns and a marked induction of CA9 protein in response to severe hypoxia. These results were paralleled by the results for HIF-1α protein under identical oxygenation conditions with a similar expression tendency to that displayed during the CA9 protein expression experimental series. Continuous stimulation with the cytokines, IL-1, IL-6, TNF-α and TGF-β, under normoxic conditions significantly increased the carbonic anhydrase 9 expression level at both the protein and mRNA level, almost doubling the CA9 mRNA and CA9 and HIF-1α protein expression levels found under hypoxia. The findings from these experiments indicated that hypoxia is a positive regulator of CA9 expression in HCC, and the four signal transduction pathways, IL-1, IL-6, TNF-α and TGF-β, positively influence CA9 expression under both normoxic and hypoxic conditions.

CONCLUSION: These findings may potentially be considered in the design of anti- cancer therapeutic approaches involving hypoxia-induced or cytokine stimulatory effects on expression. In addition, they provide evidence of the stimulatory role of the examined cytokine families resulting in an increase in CA9 expression under different oxygenation conditions in human cancer, especially HCC, and on the role of the CA9 gene as a positive disease regulator in human cancer.

Advances in understanding the relationship between hepatic hypoxia-inducible factor-1 alpha and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is characterized by hypoxia due to robust cell proliferation. Hypoxia can promote tumor cell proliferation, metastasis and neovasculogenesis, inhibit differentiation and apoptosis, and decrease chemosensitivity and radiosensitivity. Hypoxia-inducible factor-1α (HIF-1α) is a key mediator of physiological and pathological hypoxia response and controls the transcription of numerous genes that are of pivotal importance for angiogenesis and cellular metabolism. Therefore, HIF-1α is closely related with the proliferation, metastasis and apoptosis of HCC cells. Recently, HIF-1α-based gene therapy has become a novel adjunctive strategy for the management of HCC. This review focuses on the relationship between HIF-1α and the progression and therapy of HCC.

Effects of combined Tan IIA and 5-FU on cell proliferation, apoptosis, and the expression of HIF-1α and mutant P53 in human gastric cancer cell line SGC7901 under hypoxia

AIM: To investigate the effects of combined tanshinone IIA (Tan IIA) and 5-fluorouracil (5-FU) on cell proliferation, apoptosis, and the expressions of hypoxia-inducible factor-1 alpha (HIF-1α) and mutant P53 (mt P53) in human gastric cancer cell line SGC7901 under hypoxia.

METHODS: Hypoxia was induced in SGC7901 cells by cobalt dichloride treatment. SGC7901 cells under hypoxia were treated with different concentrations of Tan IIA in combination with 10.0 mg/L of 5-FU for 24, 48 and 72 hours. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay. Cell apoptosis was detected by Hoechst staining. The expression of HIF-1α and mt P53 proteins was detected by immunocytochemistry.

RESULTS: Combined Tan IIA and 5-FU significantly inhibited the proliferation of SGC7901 cells (all P < 0.01) in a dose- and time-dependent manner under hypoxia. The reduced proliferation rate of cells incubated with Tan IIA at a concentration of 10 mg/L and 5-FU for 72 hours was 67.46%. Hoechst staining showed that Tan IIA in combination with 5-FU promoted the apoptosis of SGC7901 cells in a dose- and time-dependent manner under hypoxia (all P < 0.01). Immunocytochemical staining revealed that the expression levels of HIF-1α and mt P53 proteins in SGC7901 cells under hypoxia were evidently higher than those in SGC7901 cells under normal conditions (t = 22.786 and 13.914, respectively; both P < 0.01). However, Tan IIA in combination with 5-FU significantly downregulated the expression of HIF-1α and mt P53 proteins in SGC7901 cells under hypoxia (F = 182.234 and 130.062, respectively; both P < 0.01). A significant positive correlation was noted between the expression of HIF-1α and mt P53 in SGC7901 cells (n = 5, r = 0.995, P < 0.01).

CONCLUSION: Tan IIA can significantly enhance 5-FU-mediated growth inhibition and apoptosis induction in SGC7901 cells under hypoxia perhaps by downregulating HIF-1α and mt P53 protein expression.