Critical role of hypoxia sensor--HIF-1α in VEGF gene activation. Implications for angiogenesis and tissue injury healing

Challenges facing antiangiogenesis therapy: The significant role of hypoxia-inducible factor and MET in development of resistance to anti-vascular endothelial growth factor-targeted therapies

It is now fully recognized that along with multiple physiological functions, angiogenesis is also involved in the fundamental process and pathobiology of several disorders including cancer. Recent studies have fully established the role of angiogenesis in cancer progression as well as invasion and metastasis. Consequently, many therapeutic agents such as monoclonal antibodies targeting angiogenesis pathway have been introduced in clinic with the hope for improving the outcomes of cancer therapy. Bevacizumab (Avastin®) was the first anti-vascular endothelial growth factor (VEGF) targeting monoclonal antibody developed with this purpose and soon received its accelerated US Food and Drug Administration (FDA) approval for treatment of patients with metastatic breast cancer in 2008. However, the failure to meet expecting results in different follow-up studies, forced FDA to remove bevacizumab approval for metastatic breast cancer. Investigations have now revealed that while suppressing VEGF pathway initially decreases tumor progression rate and vasculature density, activation of several interrelated pathways and signaling molecules following VEGF blockade compensate the insufficiency of VEGF and initially blocked angiogenesis, explaining in part the failure observed with bevacizumab single therapy. In present review, we introduce some of the main pathways and signaling molecules involved in angiogenesis and then propose how their interconnection may result in development of resistance to bevacizumab.

Mesenchymal Stromal Cell Secretome: Influencing Therapeutic Potential by Cellular Pre-conditioning

Mesenchymal stromal cells (MSCs) are self-renewing, culture-expandable adult stem cells that have been isolated from a variety of tissues, and possess multipotent differentiation capacity, immunomodulatory properties, and are relatively non-immunogenic. Due to this unique set of characteristics, these cells have attracted great interest in the field of regenerative medicine and have been shown to possess pronounced therapeutic potential in many different pathologies. MSCs' mode of action involves a strong paracrine component resulting from the high levels of bioactive molecules they secrete in response to the local microenvironment. For this reason, MSCs' secretome is currently being explored in several clinical contexts, either using MSC-conditioned media (CM) or purified MSC-derived extracellular vesicles (EVs) to modulate tissue response to a wide array of injuries. Rather than being a constant mixture of molecular factors, MSCs' secretome is known to be dependent on the diverse stimuli present in the microenvironment that MSCs encounter. As such, the composition of the MSCs' secretome can be modulated by preconditioning the MSCs during in vitro culture. This manuscript reviews the existent literature on how preconditioning of MSCs affects the therapeutic potential of their secretome, focusing on MSCs' immunomodulatory and regenerative features, thereby providing new insights for the therapeutic use of MSCs' secretome.

The role of mitochondria in angiogenesis

Angiogenesis extends pre-existing blood vessels to improve oxygen and nutrient delivery to inflamed or otherwise hypoxic tissues. Mitochondria are integral in this process, controlling cellular metabolism to regulate the proliferation, migration, and survival of endothelial cells which comprise the inner lining of blood vessels. Mitochondrial Complex III senses hypoxic conditions and generates mitochondrial reactive oxygen species which stabilize hypoxia-inducible factor (HIF-1α) protein. HIF-1α induces the transcription of the vegfa gene, allowing the translation of vascular endothelial growth factor protein, which interacts with mature and precursor endothelial cells, mobilizing them to form new blood vessels. This cascade can be inhibited at specific points by means of gene knockdown, enzyme treatment, and introduction of naturally occurring small molecules, providing insight into the relationship between mitochondria and angiogenesis. This review focuses on current knowledge of the overall role of mitochondria in controlling angiogenesis and outlines known inhibitors that have been used to elucidate this pathway which may be useful in future research to control angiogenesis in vivo.

A Core-Shell Nanoplatform for Synergistic Enhanced Sonodynamic Therapy of Hypoxic Tumor via Cascaded Strategy

Sonodynamic therapy (SDT) always causes tumor hypoxia aggravation which can induce malignant cell proliferation and drug resistance. To overcome these disadvantages, a cascaded drug delivery system (Lipo/HMME/ACF@MnO2 -AS1411) is constructed for synergistic enhanced sonodynamic therapy. First, hematoporphyrin monomethyl ether (HMME) and acriflavine (ACF) are encapsulated in the lipid layers and the inner aqueous cores of the liposomes, respectively. Then the ultrathin manganese dioxide (MnO2 ) nanosheets are coated on the surface of the liposomes by using KMnO4 and polyethylene glycol through "one step reduction and modification" method. Furthermore, the nanoparticles are decorated with tumor-targeting AS1411 aptamer through the phosphate groups on the DNA strand which can bind to Mn sites to obtain Lipo/HMME/ACF@MnO2 -AS1411 delivery system. Herein, HMME can act as a sonosensitizer, and ACF is used to prevent the formation of HIF-1α/HIF-1β dimerization to overcome the negative effects after SDT. The Lipo/HMME/ACF@MnO2 -AS1411 delivery system has multiple functions, including codelivery of HMME and ACF, pH/glutathione/ultrasound triple responses, synergistic cascaded enhancement of SDT, precise tumor-targeting, and magnetic resonance imaging. The in vitro and in vivo results suggest that the Lipo/HMME/ACF@MnO2 -AS1411 delivery system is a promising core-shell nanoplatform for synergistic enhancement of sonodynamic therapy, which can provide a new approach in the related research fields.

Interleukin-6 (IL-6) triggers the malignancy of hemangioma cells via activation of HIF-1α/VEGFA signals

Hemangioma (HA) is tumor formed by hyper-proliferation of vascular endothelial cells. The roles of interleukins on the progression of HA are not well illustrated. Our present study revealed that the expression of interleukin -6 (IL-6) and IL-8 in HA cells were significantly increased as compared with that in the human umbilical vein endothelial cell (HUVEC) cells. Targeted inhibition of IL-6, while not IL-8, can significantly suppress the proliferation and migration of HA cells. IL-6 treatment can increase the expression of vascular endothelial growth factor A (VEGFA), while had no significant effect on the expression of basic fibroblast growth factor (bFGF), in HA cells. Deletion of VEGFA can abolish IL-6 induced progression of HA, suggesting the essential role of VEGFA in IL-6 induced HA development. The specific inhibitor of hypoxia-inducible factor (HIF)-1α, while not Sp1, NF-κB, or AP1, abolished IL-6 induced VEGFA expression. Over expression of HIF-1α can attenuate anti-IL-6 suppressed expression of VEGFA in HA cells. Furthermore, IL-6 triggered the expression, nuclear translocation, and transcription activities of HIF-1α in HA cells via increasing its binding with the signal transducer and activator of transcription-3 (STAT3). STAT3 inhibitor CPA7 or si-STAT3 can abolish IL-6 induced upregulation of HIF-1α in HDEC cells. Collectively, our study revealed that IL-6 can trigger the malignancy of HA cells via induction of proliferation and migration. The activation of STAT3/HIF-1α/VEGFA signal was essential for this process. It suggested that IL-6/STAT3/HIF-1α/VEGFA signal may represent a novel therapeutic target for human HA treatment.

Ghrelin protects the myocardium with hypoxia/reoxygenation treatment through upregulating the expression of growth hormone, growth hormone secretagogue receptor and insulin-like growth factor-1, and promoting the phosphorylation of protein kinase B

Ghrelin is an endogenous ligand of growth hormone (GH) secretagogue receptor (GHSR) and has a number of biological effects, including heart protection. The present study aimed to reveal the positive effect of ghrelin on myocardium with hypoxia/reoxygenation (H/R) treatment and the involved molecular mechanisms. Successful construction of lentiviral expression vector (ghrelin-pLVX-Puro) was confirmed by colony polymerase chain reaction (PCR) verification. Primary rat cardiac myocytes were isolated and identified by immunofluorescence staining. Existence of red fluorescence of α-sarcomeric actinin indicated the successful isolation. Following ghrelin transfection and H/R treatment, primary cells were divided into four groups: Control, H/R, empty (empty pLVX-Puro + H/R) and ghrelin (ghrelin-pLVX-Puro + H/R). Cell viability and apoptosis were evaluated by Cell Counting Kit-8 (CCK-8) and Hoechst staining, respectively. The cell viability in the ghrelin group was significantly higher than that in the empty control group (P<0.05). The apoptosis rate in the ghrelin group was significantly lower than that in the empty control group (P<0.05). An ex vivo rat cardiac perfusion model was established. Following ghrelin incubation and H/R treatment, ex vivo myocardium was divided into four groups: Control, sham, H/R and ghrelin (ghrelin + H/R). Immunohistochemical analysis demonstrated that ghrelin increased the integrity of cardiac myocytes, and decreased shrinkage and apoptosis. mRNA and protein expression levels of GH, GHSR, insulin-like growth factor-1 (IGF-1), protein kinase B (Akt), phosphorylated Akt (p-Akt) were determined by reverse transcription (RT)-PCR, western blot analysis and immunohistochemical analysis. Ghrelin upregulated the mRNA and protein expression levels of GH, GHSR and IGF-1, and increased the ratio of p-Akt to Akt protein level (p-Akt/Akt) in cardiac myocytes and myocardial tissues with H/R treatment. In conclusion, ghrelin protected the myocardium with H/R treatment through upregulating the expression of GH, GHSR and IGF-1, and promoting the phosphorylation of Akt. This would provide promising insights into the treatment of hypoxic myocardial injury by ghrelin.

MiR-148b-3p inhibits renal carcinoma cell growth and pro-angiogenic phenotype of endothelial cell potentially by modulating FGF2

MicroRNAs (miRNAs) have been implicated in a large number of biological processes such as tumor angiogenesis. MiR-148b-3p has been identified as a tumor suppressor in multiple cancer types and the function of miR-148b-3p in renal carcinoma remains unidentified. In this study, we found that the expression of miR-148b-3p was decreased in renal carcinoma based on GEO analysis and the gain-of-function experiments revealed that miR-148b-3p promoted renal carcinoma cell apoptosis and suppressed cell proliferation, migration in vitro and tumor growth in vivo. Functionally, the tube formation, invasion and migration capabilities of human umbilical vein endothelial cells (HUVECs) were suppressed by conditioned media derived from renal carcinoma 786-O cells that were transfected with miR-148b-3p mimics. Meanwhile, these conditioned media inhibited the proliferation and promoted apoptosis of HUVECs. The key angiogenesis inducer hypoxia inducible factor-1α (HIF-1α) and the pro-angiogenic mediators were decreased in 786-O cells that were transfected with miR-148b-3p mimics. Mechanistically, miR-148b-3p could target fibroblast growth factor-2 (FGF2) and further impaired the activation of fibroblast growth factor receptor 2 (FGFR2). Taken together, our findings demonstrate that miR-148b-3p attenuates renal carcinoma cell growth, the invasion and tube formation of endothelial cell potentially via regulating FGF2-FGFR2 signaling pathway.

MTA1 promotes the invasion and migration of pancreatic cancer cells potentially through the HIF-α/VEGF pathway

The metastasis-associated gene 1 (MTA1) has previously been recognized as an oncogene, and abnormal MTA1 expression has been related to progression of numerous cancer types to the metastasis stage. However, the function of MTA1 in the regulation of pancreatic cancer progression and metastasis remains unclear. Western blot analysis was adopted to determine the expression of MTA1 in pancreatic cancer tissues and corresponding near normal tissues. Steady clone with MTA1-overexpression and MTA1-inhibitionweregenerated via lentivirus technology in BxPc-3 cells. Transwell assay was carried out for detecting the invasion of pancreatic cancer cells. The migration activity was assessed using the wound scratch assay. The effect of MTA1 in pancreatic cancer was evaluated in the mice xenografts. Western blot analysis was employed to determine the expression of hypoxia inducible factor-α (HIF-α) and vascular endothelial growth factor (VEGF) in vitro and in vivo. We observed that MTA1 overexpression enhanced migration and invasion ability of pancreatic cancer cells in vitro and increased HIF-α and VEGF protein levels in vitro and in vivo. MTA1 inhibition had the opposite effects. MTA1 protein level was positively related to HIF-α and VEGF protein levels. These results indicated that MTA1 potentially promoted pancreatic cancer metastasis via HIF-α/VEGF pathway. This research supplies a new molecular mechanism for MTA1 in the pancreatic cancer progression and metastasis. MTA1 may be an effective therapy target in pancreatic cancer.

Closed Incision Negative Pressure Therapy Reduces Surgical Site Infections in Vascular Surgery: A Prospective Randomised Trial (AIMS Trial)

BACKGROUND

Surgical site infections (SSIs) of the groin remain a crucial problem in vascular surgery, prompting great interest in preventative techniques, such as closed incision negative pressure therapy (ciNPT). This prospective randomised study aimed to assess the potential benefits of ciNPT application after groin incisions for vascular surgery.

METHOD

The study included 204 patients who underwent vascular surgery for peripheral artery disease (PAD) at two sites between July 2015 and May 2017. These patients received post-operative treatment with ciNPT (intervention group) or standard wound dressings (control group). After exclusion, 188 patients were assessed for SSIs using the Szilagyi classification.

RESULTS

The mean patient age was 66.6 ± 9.4 years (range 43-85 years), and 70% were male (n = 132). Regarding PAD stage, 52% were stage IIB, 28% stage III, and 19% stage IV. Among the patients, 45% (n = 85) had had a previous groin incision. Bacterial swabs were performed in each case of suspected SSI (22.8% [43/188]), while 76.7% (33/188) were negative, there were 5% [5/98] positive swabs in the intervention group and 5.5% [5/90] in the control group). Antibiotics were given to 13.2% of the intervention group, and 31.1% of the control group (p = .004). The control group experienced more frequent SSIs (33.3%; 30/90) than the intervention group (13.2%; 13/98; p = .0015; absolute risk difference -20.1 per 100; 95% CI -31.9 to 8.2). This difference was based on an increased rate of Szilagyi I SSI in the control group (24.6% vs. 8.1%, p = .0012).

CONCLUSION

The results confirmed a reduced superficial SSI rate after vascular surgical groin incision using ciNPT compared with standard wound dressings.

Obstructive Sleep Apnea Monocytes Exhibit High Levels of Vascular Endothelial Growth Factor Secretion, Augmenting Tumor Progression

Obstructive sleep apnea (OSA) is a syndrome characterized by repeated pauses in breathing induced by a partial or complete collapse of the upper airways during sleep. Intermittent hypoxia (IH), a hallmark characteristic of OSA, has been proposed to be a major determinant of cancer development, and patients with OSA are at a higher risk of tumors. Both OSA and healthy monocytes have been found to show enhanced HIF1α expression under IH. Moreover, these cells under IH polarize toward a tumor-promoting phenotype in a HIF1α-dependent manner and influence tumor growth via vascular endothelial growth factor (VEGF). Monocytes from patients with OSA increased the tumor-induced microenvironment and exhibited an impaired cytotoxicity in a 3D tumor in vitro model as a result of the increased HIF1α secretion. Adequate oxygen restoration both in vivo (under continuous positive airway pressure treatment, CPAP) and in vitro leads the monocytes to revert the tumor-promoting phenotype, demonstrating the plasticity of the innate immune system and the oxygen recovery relevance in this context.

Triptolide inhibits vascular endothelial growth factor-mediated angiogenesis in human breast cancer cells

Triptolide has been demonstrated to induce tumor cell apoptosis. However, the role of triptolide in breast cancer angiogenesis remains unclear. The present study aimed to investigate the function of triptolide in breast cancer and the molecular mechanisms underlying this. The results revealed that triptolide could significantly decrease the expression of vascular endothelial growth factor A (VEGFA) in Hs578T and MDAMB231 breast cancer cells. Furthermore, human umbilical vein endothelial cells were used to perform tube formation and bromodeoxyuridine incorporation assays, which demonstrated an antiangiogenic effect of triptolide. In addition, the effect of triptolide in vivo was examined in a xenograft mouse model, which determined that VEGFA, cluster of differentiation 31 and anti-proliferation marker protein Ki67 expression in tumor sections was decreased in the triptolide treatment group compared with the control group. Western bolt analysis was performed to investigate the phosphorylation of extracellular signal-related kinase (ERK)1/2 and RAC-α serine/threonine-protein kinase after triptolide treatment, and it's effect on hypoxia inducible factor (HIF)1-α expression. The results demonstrated that triptolide suppressed ERK1/2 activation and HIF1-α expression. Furthermore, overexpression of HIF1-α could partially abrogate the inhibitory effect of triptolide on VEGFA expression. These results suggest that triptolide inhibits breast cancer cell angiogenesis in vitro and in vivo through inhibiting the ERK1/2-HIF1-α-VEGFA axis.

Effects of thalidomide on growth and VEGF-A expression in SW480 colon cancer cells

Lymphatic and hematogenous spread are the most common ways for tumors to metastasize. Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) particularly VEGF-A is important in the process of angiogenesis. The current research has indicated that thalidomide (THD) may be able to inhibit angiogenesis, stimulate the activity of the immune system and inhibit the adherence of cancer cells to stromal cells. These changes may lead to suppression of tumor occurrence and development. To date, to the best of our knowledge, the effects of THD on colon cancer SW480 cells have not been reported. In the present study, the effects of THD and a combination of THD and oxaliplatin (L-OHP) on the proliferation of SW480 cells have been investigated. Furthermore, the expression of VEGF-A and hypoxia-inducible factor 1 (HIF-1) was analyzed using MTT assay, quantitative polymerase chain reaction and western blot analysis. The results indicated that THD was able to inhibit SW480 cells in dose-and-time dependent manner and inhibit the expression of VEGF-A and HIF-1α. Furthermore, treatment with THD and L-OHP had synergistic inhibitory effect, which may provide a novel treatment strategy for advanced colorectal cancer.

Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation

Photobiomodulation (PBM) involves the use of red or near-infrared light at low power densities to produce a beneficial effect on cells or tissues. PBM therapy is used to reduce pain, inflammation, edema, and to regenerate damaged tissues such as wounds, bones, and tendons. The primary site of light absorption in mammalian cells has been identified as the mitochondria and, more specifically, cytochrome c oxidase (CCO). It is hypothesized that inhibitory nitric oxide can be dissociated from CCO, thus restoring electron transport and increasing mitochondrial membrane potential. Another mechanism involves activation of light or heat-gated ion channels. This review will cover the redox signaling that occurs in PBM and examine the difference between healthy and stressed cells, where PBM can have apparently opposite effects. PBM has a marked effect on stem cells, and this is proposed to operate via mitochondrial redox signaling. PBM can act as a preconditioning regimen and can interact with exercise on muscles.

Zinc supplementation does not influence serum levels of VEGF, BDNF, and NGF in diabetic retinopathy patients: a randomized controlled clinical trial

Objectives: This study was aimed to evaluate the effects of zinc (Zn) supplementation on serum levels of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) in patients with diabetic retinopathy (DR). Methods: In this randomized clinical trial, 50 patients with DR were allocated into the Zn (n = 25) and placebo (n = 25) groups to receive 30 mg Zn gluconate or maltose dextrin per day, respectively, for three months. Metabolic parameters and blood pressure were measured. Serum levels of Zn were assessed by atomic absorption spectrophotometry and serum levels of VEGF, BDNF and NGF by ELISA. Results: Forty-five patients completed the intervention. Levels of VEGF, BDNF and NGF were not affected by the Zn supplementation. Levels of VEGF correlated negatively with levels of Zn and positively with BDNF and NGF. There was also a positive correlation between BDNF and NGF. Serum levels of VEGF, BDNF and NGF were negatively correlated with serum levels of the diabetic parameters measured. Conclusions: Strong positive relationship between the growth factors and their inverse association with metabolic factors is possibly suggesting the contribution of these factors in the pathogenesis of DR through acting in a same biological pathway.