Development of Inhibitors Targeting Hypoxia-Inducible Factor 1 and 2 for Cancer Therapy

Total synthesis and biological evaluation of 7-hydroxyneolamellarin A as hypoxia-inducible factor-1α inhibitor for cancer therapy

7-Hydroxyneolamellarin A (7-OH-Neo A, 1), a natural marine product derived from sponge Dendrilla nigra, was first synthesized with 10% overall yield under the instruction of convergent synthetic strategy. We found that 7-OH-Neo A could attenuate the accumulation of hypoxia-inducible factor-1α (HIF-1α) protein and inhibit vascular epidermal growth factor (VEGF) transcriptional activity, showing well inhibitory effect on HIF-1 signaling pathway. Meantime, 7-OH-Neo A had the well anti-tumor activities, such as inhibiting tumor angiogenesis, proliferation, migration and invasion. More importantly, 7-OH-Neo A exhibited profound anti-tumor effect in mice breast cancer model by suppressing the accumulation of HIF-1α in tumor tissue. Mechanism study demonstrated that 7-OH-Neo A might target the protein with the ability of stabilizing HIF-1α in hypoxia. Due to the excellent water solubility, superior anti-tumor activity and good biocompatibility, 7-OH-Neo A shows the promising potential for being exploited as an anti-tumor agent in near future.

Targeting iron metabolism in cancer therapy

Iron is a critical component of many cellular functions including DNA replication and repair, and it is essential for cell vitality. As an essential element, iron is critical for maintaining human health. However, excess iron can be highly toxic, resulting in oxidative DNA damage. Many studies have observed significant associations between iron and cancer, and the association appears to be more than just coincidental. The chief characteristic of cancers, hyper-proliferation, makes them even more dependent on iron than normal cells. Cancer therapeutics are becoming as diverse as the disease itself. Targeting iron metabolism in cancer cells is an emerging, formidable field of therapeutics. It is a strategy that is highly diverse with regard to specific targets and the various ways to reach them. This review will discuss the importance of iron metabolism in cancer and highlight the ways in which it is being explored as the medicine of tomorrow.

Combinatorial therapy in tumor microenvironment: Where do we stand?

The tumor microenvironment plays a pivotal role in tumor initiation and progression by creating a dynamic interaction with cancer cells. The tumor microenvironment consists of various cellular components, including endothelial cells, fibroblasts, pericytes, adipocytes, immune cells, cancer stem cells and vasculature, which provide a sustained environment for cancer cell proliferation. Currently, targeting tumor microenvironment is increasingly being explored as a novel approach to improve cancer therapeutics, as it influences the growth and expansion of malignant cells in various ways. Despite continuous advancements in targeted therapies for cancer treatment, drug resistance, toxicity and immune escape mechanisms are the basis of treatment failure and cancer escape. Targeting tumor microenvironment efficiently with approved drugs and combination therapy is the solution to this enduring challenge that involves combining more than one treatment modality such as chemotherapy, surgery, radiotherapy, immunotherapy and nanotherapy that can effectively and synergistically target the critical pathways associated with disease pathogenesis. This review shed light on the composition of the tumor microenvironment, interaction of different components within tumor microenvironment with tumor cells and associated hallmarks, the current status of combinatorial therapies being developed, and various growing advancements. Furthermore, computational tools can also be used to monitor the significance and outcome of therapies being developed. We addressed the perceived barriers and regulatory hurdles in developing a combinatorial regimen and evaluated the present status of these therapies in the clinic. The accumulating depth of knowledge about the tumor microenvironment in cancer may facilitate further development of effective treatment modalities. This review presents the tumor microenvironment as a sweeping landscape for developing novel cancer therapies.

Allergic Asthma-Induced Cognitive Impairment is Alleviated by Dexamethasone

Allergic asthma is a typical chronic inflammatory disease of respiratory tract. Clinical data shows that patients with allergic asthma have different degrees of cognitive dysfunction. The molecular mechanism underlying the pathogenesis of asthma-induced cognitive disorder is not yet well defined. Dexamethasone (DEX), one of the first-line drugs being widely used in the treatment of asthma, has not been reported to have an effect on cognitive dysfunction in mice model. To investigate the effect of asthma on cognitive impairment as well as the effect of DEX on asthma-caused morphological and behavioral changes, C57BL/6J mice received treatment with house dust mites (HDM) for 60 days to become allergic asthma model mice, and a group of HDM-treated asthma model mice were treated with DEX. HDM-treated asthma model mice exhibited increased airway hyperresponsiveness (AHR) and inflammatory infiltration in lung tissue. An elevated level of IL-4, IL-5, and TNF-α was detected in bronchoalveolar lavage fluid (BALF) by Luminex liquid suspension chip. Asthma model mice also presented memory deficits accompanied with morphological changes at the synaptic levels in the cortex and hippocampus. Meanwhile, vascular edema and increased expression of HIF-1α and HIF-2α were found in the brain of asthma model mice. Interestingly, DEX treatment could reverse the inflammatory changes in asthma model mice airway, rescue the cognitive impairment and improve the synaptic plasticity. Besides, DEX significantly decreased the expression of HIF-1α and HIF-2α in mice brain and lung. These processes may be used to decipher the complex interplay and pathological changes between asthma and cognition. This study provides laboratory evidence for the prevention and treatment of cognitive malfunction induced by asthma.

Metabolic regulation in the immune response to cancer

Metabolic reprogramming in tumor‐immune interactions is emerging as a key factor affecting pro‐inflammatory carcinogenic effects and anticancer immune responses. Therefore, dysregulated metabolites and their regulators affect both cancer progression and therapeutic response. Here, we describe the molecular mechanisms through which microenvironmental, systemic, and microbial metabolites potentially influence the host immune response to mediate malignant progression and therapeutic intervention. We summarized the primary interplaying factors that constitute metabolism, immunological reactions, and cancer with a focus on mechanistic aspects. Finally, we discussed the possibility of metabolic interventions at multiple levels to enhance the efficacy of immunotherapeutic and conventional approaches for future anticancer treatments.

Therapy Resistance in Cancers: Phenotypic, Metabolic, Epigenetic and Tumour Microenvironmental Perspectives

BACKGROUND

Chemoresistance is a vital problem in cancer therapy where cancer cells develop mechanisms to encounter the effect of chemotherapeutics, resulting in cancer recurrence. In addition, chemotherapy- resistant leads to the formation of a more aggressive form of cancer cells, which, in turn, contributes to the poor survival of patients with cancer.

OBJECTIVE

In this review, we aimed to provide an overview of how the therapy resistance property evolves in cancer cells, contributing factors and their role in cancer chemoresistance, and exemplified the problems of some available therapies.

METHODS

The published literature on various electronic databases including, Pubmed, Scopus, Google scholar containing keywords cancer therapy resistance, phenotypic, metabolic and epigenetic factors, were vigorously searched, retrieved and analyzed.

RESULTS

Cancer cells have developed a range of cellular processes, including uncontrolled activation of Epithelial- Mesenchymal Transition (EMT), metabolic reprogramming and epigenetic alterations. These cellular processes play significant roles in the generation of therapy resistance. Furthermore, the microenvironment where cancer cells evolve effectively contributes to the process of chemoresistance. In tumour microenvironment immune cells, Mesenchymal Stem Cells (MSCs), endothelial cells and cancer-associated fibroblasts (CAFs) contribute to the maintenance of therapy-resistant phenotype via the secretion of factors that promote resistance to chemotherapy.

CONCLUSION

To conclude, as these factors hinder successful cancer therapies, therapeutic resistance property of cancer cells is a subject of intense research, which in turn could open a new horizon to aim for developing efficient therapies.

Temporal Quantitative Proteomics Reveals Proteomic and Phosphoproteomic Alterations Associated with Adaptive Response to Hypoxia in Melanoma Cells

Simple Summary

Most solid tumours, including melanoma (skin cancer), are riddled with areas lacking adequate oxygen supply due to insufficient vasculature. Cancer cells in these regions are resistant to therapies and contribute to cancer spread and poor treatment response in patients. Understanding the mechanisms by which cancer cells adapt to survive in such a hostile environment will provide novel avenues for treatment. In this study, we investigated mechanisms that melanoma cells use to adapt and survive in an oxygen-poor environment. We used four different melanoma cell lines and studied how protein levels and phosphorylation patterns on thousands of proteins change when the cells are exposed to poor oxygen conditions. This revealed potential mechanisms on which cancer cells are dependent for survival. These survival mechanisms can be potentially targeted to achieve durable response to therapy. We demonstrate this by targeting one such mechanism required for cancer cell survival.

Abstract

Hypoxia is a common feature in various solid tumours, including melanoma. Cancer cells in hypoxic environments are resistant to both chemotherapy and radiation. Hypoxia is also associated with immune suppression. Identification of proteins and pathways that regulate cancer cell survival in hypoxic environments can reveal potential vulnerabilities that can be exploited to improve the efficacy of anticancer therapies. We carried out temporal proteomic and phosphoproteomic profiling in melanoma cell lines to identify hypoxia-induced protein expression and phosphorylation changes. By employing a TMT-based quantitative proteomics strategy, we report the identification and quantitation of >7000 proteins and >10,000 phosphosites in melanoma cell lines grown in hypoxia. Proteomics data show metabolic reprogramming as one of the prominent adaptive responses in hypoxia. We identify several novel hypoxia-mediated phosphorylation changes that have not been reported before. They reveal kinase signalling pathways that are potentially involved in modulating cellular response to hypoxia. In addition to known protein expression changes, we identify several novel proteomic alterations associated with adaptive response to hypoxia. We show that cancer cells require the ubiquitin–proteasome system to survive in both normoxia and hypoxia. Inhibition of proteasome activity affects cell survival and may provide a novel therapeutic avenue to target cancer cells in hypoxia. Our study can serve as a valuable resource to pursue novel candidates to target hypoxia in cancers and improve the efficacy of anticancer therapies.

Hypoxia and viral infectious diseases

Oxygen-sensing mechanisms allow cells to adapt and respond to changes in cellular oxygen tension, including hypoxic conditions. Hypoxia-inducible factor (HIF) is a central mediator in this fundamental adaptive response, and has critical functions in normal and disease physiology. Viruses have been shown to manipulate HIFs during their life cycle to facilitate replication and invasion. Conversely, HIFs are also implicated in the development of the host immune system and response to viral infections. Here, we highlight the recent revelations of host-pathogen interactions that involve the hypoxic response pathway and the role of HIF in emerging viral infectious diseases, as well as discussing potential antiviral therapeutic strategies targeting the HIF signaling axis.

Hypoxia-Inducible Factor-2α as a Novel Target in Renal Cell Carcinoma

Hypoxia-inducible factor (HIF), an important mediator of hypoxia response, is implicated in tumorigenesis in the setting of pseudohypoxia, such as in the inactivation of von Hippel-Lindau tumor suppressor protein (pVHL), leading to development and progression of clear cell renal cell carcinoma (ccRCC). Targeting downstream molecules in HIF pathway, such as vascular endothelial growth factor (VEGF), has led to improvement in clinical outcome for patients with advanced ccRCC, but such therapy thus far has been limited by eventual resistance and treatment failure. Following the discovery of HIF-2α playing a key role in ccRCC carcinogenesis, inhibitors targeting HIF-2α have been developed and have demonstrated encouraging efficacy and safety profile in clinical trials. This review discusses HIF-2α as a promising therapeutic target for ccRCC.

Functional vinorelbine plus schisandrin B liposomes destroying tumor metastasis in treatment of gastric cancer

Gastric cancer is one of the leading causes of cancer-related death worldwide with a poor prognosis. Gastric cancer is usually treated with surgery and chemotherapy, accompanied by a high rate of metastasis and recurrence. In this paper, R₈ (RRRRRRRR) modified vinorelbine plus schisandrin B liposomes had been successfully constructed for treating gastric cancer. In the liposomes, R₈ was used to enhance the intracellular uptake, schisandrin B was incorporated into liposomes for inhibiting tumor cells metastasis, and vinorelbine was encapsulated into liposomes as antitumor drugs. Studies were performed on BGC-823 cells in vitro and were verified in the BGC-823 cell xenografts nude mice in vivo. Results in vitro demonstrated that the targeting liposomes could induce BGC-823 cells apoptosis, inhibit the metastasis of tumor cells, and increase targeting effects to tumor cells. Meanwhile, action mechanism studies showed that the targeting liposomes could down-regulate VEGF, VE-Cad, HIF-1a, PI3K, MMP-2, and FAK to inhibit tumor metastasis. In vivo results exhibited that the targeting liposomes displayed an obvious antitumor efficacy by accumulating selectively in tumor site and induce tumor cell apoptosis. Hence, R₈ modified vinorelbine plus schisandrin B liposomes might provide a safe and efficient therapy strategy for gastric cancer.

Flavonoids Targeting HIF-1: Implications on Cancer Metabolism

Tumor hypoxia is described as an oxygen deprivation in malignant tissue. The hypoxic condition is a consequence of an imbalance between rapidly proliferating cells and a vascularization that leads to lower oxygen levels in tumors. Hypoxia-inducible factor 1 (HIF-1) is an essential transcription factor contributing to the regulation of hypoxia-associated genes. Some of these genes modulate molecular cascades associated with the Warburg effect and its accompanying pathways and, therefore, represent promising targets for cancer treatment. Current progress in the development of therapeutic approaches brings several promising inhibitors of HIF-1. Flavonoids, widely occurring in various plants, exert a broad spectrum of beneficial effects on human health, and are potentially powerful therapeutic tools against cancer. Recent evidences identified numerous natural flavonoids and their derivatives as inhibitors of HIF-1, associated with the regulation of critical glycolytic components in cancer cells, including pyruvate kinase M2(PKM2), lactate dehydrogenase (LDHA), glucose transporters (GLUTs), hexokinase II (HKII), phosphofructokinase-1 (PFK-1), and pyruvate dehydrogenase kinase (PDK). Here, we discuss the results of most recent studies evaluating the impact of flavonoids on HIF-1 accompanied by the regulation of critical enzymes contributing to the Warburg phenotype. Besides, flavonoid effects on glucose metabolism via regulation of HIF-1 activity represent a promising avenue in cancer-related research. At the same time, only more-in depth investigations can further elucidate the mechanistic and clinical connections between HIF-1 and cancer metabolism.

Long Noncoding RNA Expression Profiling Reveals Upregulation of Uroplakin 1A and Uroplakin 1A Antisense RNA 1 under Hypoxic Conditions in Lung Cancer Cells

Hypoxia plays important roles in cancer progression by inducing angiogenesis, metastasis, and drug resistance. However, the effects of hypoxia on long noncoding RNA (lncRNA) expression have not been clarified. Herein, we evaluated alterations in lncRNA expression in lung cancer cells under hypoxic conditions using lncRNA microarray analyses. Among 40,173 lncRNAs, 211 and 113 lncRNAs were up- and downregulated, respectively, in both A549 and NCI-H460 cells. Uroplakin 1A (UPK1A) and UPK1A-antisense RNA 1 (AS1), which showed the highest upregulation under hypoxic conditions, were selected to investigate the effects of UPK1AAS1 on the expression of UPK1A and the mechanisms of hypoxia-inducible expression. Following transfection of cells with small interfering RNA (siRNA) targeting hypoxiainducible factor 1α (HIF-1α), the hypoxia-induced expression of UPK1A and UPK1A-AS1 was significantly reduced, indicating that HIF-1α played important roles in the hypoxiainduced expression of these targets. After transfection of cells with UPK1A siRNA, UPK1A and UPK1A-AS1 levels were reduced. Moreover, transfection of cells with UPK1A-AS1 siRNA downregulated both UPK1A-AS1 and UPK1A. RNase protection assays demonstrated that UPK1A and UPK1A-AS1 formed a duplex; thus, transfection with UPK1A-AS1 siRNA decreased the RNA stability of UPK1A. Overall, these results indicated that UPK1A and UPK1A-AS1 expression increased under hypoxic conditions in a HIF-1α-dependent manner and that formation of a UPK1A/UPK1A-AS1 duplex affected RNA stability, enabling each molecule to regulate the expression of the other.

Thioredoxin-dependent system. Application of inhibitors

One of the systems responsible for maintaining cellular redox homeostasis is the thioredoxin-dependent system. An equally important function of this system is the regulation of the expression of many proteins by the transcription factor NF-κB or the apoptosis regulating kinase (ASK-1). Since it has been shown that the Trx-dependent system can contribute to both the enhancement of tumour angiogenesis and growth as well as apoptosis of neoplastic cells, the search for compounds that inhibit the level/activity of Trx and/or TrxR and thus modulate the course of the neoplastic process is ongoing. It has been shown that many naturally occurring polyphenolic compounds inactivate elements of the thioredoxin system. In addition, the effectiveness of Trx is inhibited by imidazole derivatives, while the activity of TrxR is reduced by transition metal ions complexes, dinitrohalobenzene derivatives, Michael acceptors, nitrosourea and ebselen. In addition, research is ongoing to identify new selective Trx/TrxR inhibitors.

Balanophorin B inhibited glycolysis with the involvement of HIF-1α

AIMS

Cancer cells exhibit a metabolic change called aerobic glycolysis compared with normal cells. Balanophorin B is a terpenoid ingredient reported from the genus Balanophora. In this research, we studied the effect of balanophorin B on glycolysis of HepG2 cells and Huh-7 cells under hypoxia.

MAIN METHODS

The Warburg effect was monitored by assessing glucose uptake, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Key enzymes in the glycolytic pathway and HIF-1α protein expression and degradation were analyzed by real-time PCR and western blotting. The anti-cancer effect of balanophorin B in vivo was also investigated.

KEY FINDINGS

Balanophorin B inhibited the proliferation, glucose uptake, and ECAR in both HepG2 cells and Huh-7 cells. In addition, balanophorin B inhibited the protein level of HIF-1α and its downstream targets LDHA and HKII under hypoxia, whereas HIF-1α mRNA level did not change after balanophorin B treatment. The HIF-1α plasmid reversed the inhibition of balanophorin B on glycolysis, and the proteasome inhibitor MG132 attenuated the effect of balanophorin B on HIF-1α protein expression, suggesting that balanophorin B might post-transcriptionally affect HIF-1α. Moreover, balanophorin B increased the expression of VHL and PHD2. HIF-1α siRNA also greatly attenuated the inhibitory effect of balanophorin B on HepG2 cells glucose uptake. Balanophorin B significantly inhibited tumor growth in vivo, without causing obvious toxicity to mice.

SIGNIFICANCE

These data suggest that balanophorin B inhibits glycolysis probably via an HIF-1α-dependent pathway, and the ubiquitin-proteasome pathway was greatly involved in the induction of balanophorin B on HIF-1α degradation.

Precise Deposition of Polydopamine on Cancer Cell Membrane as Artificial Receptor for Targeted Drug Delivery

Compared with conventional chemotherapy and radiotherapy, targeted molecular therapy, e.g., antibody-drug conjugates or aptamer-drug conjugates, can specifically identify overexpressed natural receptors on the cancer cell, perform targeted release of anticancer drugs, and achieve targeted killing of tumor cells. However, many natural receptors are also expressed on non-cancer cells, thereby diverting the targeting molecules to healthy cells. By generating artificial cell surface receptors specific to diseased cells, aptamer-drug conjugates can identify these artificial receptors, improve therapeutic efficacy, and decrease the minimum effective dosage. In this study, we use high K⁺ and high H₂O₂ of the tumor microenvironment (TME) to produce polydopamine only on living cancer cell membrane. Owing to the significant reactivity of polydopamine with amino groups, e.g., the amino group of proteins, polydopamine can deposit on tumor cells and act as “artificial receptors” for targeted delivery of anticancer drugs with amino groups, in other words, amino-containing drugs and protein drugs.

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Polydopamine (PDA) generation catalyzed using G-quadruplex DNAzyme

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TME high K⁺ and H₂O₂ employed to produce PDA only on cancerous cells membrane

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PDA generated and deposited on cancerous cells and acted as artificial receptors

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PDA artificial receptors facilitated targeted delivery of drugs with amino groups

An Inside Job: Applications of Intracellular Single Domain Antibodies

Sera of camelid species contain a special kind of antibody that consists only of heavy chains. The variable antigen binding domain of these heavy chain antibodies can be expressed as a separate entity, called a single domain antibody that is characterized by its small size, high solubility and oftentimes exceptional stability. Because of this, most single domain antibodies fold correctly when expressed in the reducing environment of the cytoplasm, and thereby retain their antigen binding specificity. Single domain antibodies can thus be used to target a broad range of intracellular proteins. Such intracellular single domain antibodies are also known as intrabodies, and have proven to be highly useful tools for basic research by allowing visualization, disruption and even targeted degradation of intracellular proteins. Furthermore, intrabodies can be used to uncover prospective new therapeutic targets and have the potential to be applied in therapeutic settings in the future. In this review we provide a brief overview of recent advances in the field of intracellular single domain antibodies, focusing on their use as research tools and potential therapeutic applications. Special attention is given to the available methods that allow delivery of single domain antibodies into cells.

Hypoxia-mediated drug resistance in breast cancers

Tissue hypoxia in solid tumors is caused by several pathological changes associated with tumor growth, including altered microvasculature structure, increased diffusional distances, and tumor-associated anemia. As the oxygen tension decreases, tumor cells adapt to the limited oxygen supply. Previous studies have shown that such adaptation leads to an aggressive phenotype that is resistant to many anti-cancer therapies. Induction of hypoxia inducible factors (HIFs) mediates many proteomic and genomic changes associated with tumor hypoxia. In breast cancers, HIFs not only predict poor prognosis, but also promote metastasis and drug resistance. Several studies have proposed HIF-1α as a druggable target in drug-resistant breast cancers, leading to the synthesis and development of small molecule inhibitors. Disappointingly, however, none of these small molecule inhibitors have progressed to clinical use. In this review, we briefly discuss the role of HIF-1α in breast cancer drug resistance and summarize the current and future approaches to targeting this transcription factor in breast cancer treatment.

Contribution of hypoxia inducible factor-1 during viral infections

Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that plays critical roles during the cellular response to hypoxia. Under normoxic conditions, its function is tightly regulated by the degradation of its alpha subunit (HIF-1α), which impairs the formation of an active heterodimer in the nucleus that otherwise regulates the expression of numerous genes. Importantly, HIF-1 participates in both cancer and infectious diseases unveiling new therapeutic targets for those ailments. Here, we discuss aspects related to the activation of HIF-1, the effects of this transcription factor over immune system components, as well as the involvement of HIF-1 activity in response to viral infections in humans. Although HIF-1 is currently being assessed in numerous clinical settings as a potential therapy for different diseases, up to date, there are no clinical studies evaluating the pharmacological modulation of this transcription factor as a possible new antiviral treatment. However, based on the available evidence, clinical trials targeting this molecule are likely to occur soon. In this review we discuss the role of HIF-1 in viral immunity, the modulation of HIF-1 by different types of viruses, as well as the effects of HIF-1 over their life cycle and the potential use of HIF-1 as a new target for the treatment of viral infections.

A Review of Natural Therapies Potentially Relevant in Triple Negative Breast Cancer Aimed at Targeting Cancer Cell Vulnerabilities

We reviewed the research into the mechanisms of growth of triple negative breast cancer (TNBC) based on laboratory pre-clinical studies that have shaped understanding of the disease over the past decade. In response to these findings, we propose an approach to potentially prevent cancer metabolic adaptation and recurrence. This paper collates pre-clinical results, first to determine the tumor’s mechanisms of growth and then to source natural substances that could potentially suppress those mechanisms. The results from in vivo and in vitro studies of TNBC were combined first to select 10 primary mechanisms (Hypoxia-inducible factor 1α, Hedgehog, MAPK, MTAP, NF-κ B, Notch, P13K, STAT3, and Wnt signaling pathways plus p53 and POL2A gene expression) that promote TNBC growth, and second to propose a treatment array of 21 natural compounds that suppress laboratory models of TNBC via these mechanisms. We included BRCA mutations in the review process, but only pathways with the most preclinical studies utilizing natural products were included. Then we outlined potential biomarkers to assess the changes in the micro-environment and monitor biochemical pathway suppression. This suppression-centric aim targets these mechanisms of growth with the goal of potentially halting tumor growth and preventing cancer cell metabolic adaptation. We chose TNBC to demonstrate this 5-step strategy of supplementary therapy, which may be replicated for other tumor types.

Pathological angiogenesis and inflammation in tissues

The role of angiogenesis in the growth of organs and tumors is widely recognized. Vascular-organ interaction is a key mechanism and a concept that enables an understanding of all biological phenomena and normal physiology that is essential for human survival under pathological conditions. Recently, vascular endothelial cells have been classified as a type of innate immune cells that are dependent on the pathological situations. Moreover, inflammatory cytokines and signaling regulators activated upon exposure to infection or various stresses play crucial roles in the pathological function of parenchymal cells, peripheral immune cells, stromal cells, and cancer cells in tissues. Therefore, vascular-organ interactions as a vascular microenvironment or tissue microenvironment under physiological and pathological conditions are gaining popularity as an interesting research topic. Here, we review vascular contribution as a major factor in microenvironment homeostasis in the pathogenesis of normal as well as cancerous tissues. Furthermore, we suggest that the normalization strategy of pathological angiogenesis could be a promising therapeutic target for various diseases, including cancer.

Re-engineering natural products to engage new biological targets

Covering: up to 2020 Natural products have a long history in drug discovery, with their inherent biological activity often tailored by medicinal chemists to arrive at the final drug product. This process is illustrated by numerous examples, including the conversion of epothilone to ixabepilone, erythromycin to azithromycin, and lovastatin to simvastatin. However, natural products are also fruitful starting points for the creation of complex and diverse compounds, especially those that are markedly different from the parent natural product and accordingly do not retain the biological activity of the parent. The resulting products have physiochemical properties that differ considerably when compared to traditional screening collections, thus affording an opportunity to discover novel biological activity. The synthesis of new structural frameworks from natural products thus yields value-added compounds, as demonstrated in the last several years with multiple biological discoveries emerging from these collections. This Highlight details a handful of these studies, describing new compounds derived from natural products that have biological activity and cellular targets different from those evoked/engaged by the parent. Such re-engineering of natural products offers the potential for discovering compounds with interesting and unexpected biological activity.

Mechanisms of Taxane Resistance

The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.

Calcitriol Suppresses HIF-1 and HIF-2 Transcriptional Activity by Reducing HIF-1/2α Protein Levels via a VDR-Independent Mechanism

Hypoxia-inducible transcription factors 1 and 2 (HIFs) are major mediators of cancer development and progression and validated targets for cancer therapy. Although calcitriol, the biologically active metabolite of vitamin D, was attributed with anticancer properties, there is little information on the effect of calcitriol on HIFs and the mechanism underling this activity. Here, we demonstrate the negative effect of calcitriol on HIF-1/2α protein levels and HIF-1/2 transcriptional activity and elucidate the molecular mechanism of calcitriol action. We also reveal that the suppression of vitamin D receptor (VDR) expression by siRNA does not abrogate the negative regulation of HIF-1α and HIF-2α protein levels and HIF-1/2 transcriptional activity by calcitriol, thus testifying that the mechanism of these actions is VDR independent. At the same time, calcitriol significantly reduces the phosphorylation of Akt protein kinase and its downstream targets and suppresses HIF-1/2α protein synthesis by inhibiting HIF1A and EPAS1 (Endothelial PAS domain-containing protein 1) mRNA translation, without affecting their mRNA levels. On the basis of the acquired data, it can be proposed that calcitriol reduces HIF-1α and HIF-2α protein levels and inhibits HIF-1 and HIF-2 transcriptional activity by a VDR-independent, nongenomic mechanism that involves inhibition of PI3K/Akt signaling pathway and suppression of HIF1A and EPAS1 mRNA translation.

Consecutive Hypoxia Decreases Expression of NOTCH3, HEY1, CC10, and FOXJ1 via NKX2-1 Downregulation and Intermittent Hypoxia-Reoxygenation Increases Expression of BMP4, NOTCH1, MKI67, OCT4, and MUC5AC via HIF1A Upregulation in Human Bronchial Epithelial Cells

Previous studies have shown that the experimental models of hypoxia-reoxygenation (H/R) mimics the physiological conditions of ischemia-reperfusion and induce oxidative stress and injury in various types of organs, tissues, and cells, both in vivo and in vitro, including human lung adenocarcinoma epithelial cells. Nonetheless, it had not been reported whether H/R affected proliferation, apoptosis, and expression of stem/progenitor cell markers in the bronchial epithelial cells. In this study, we investigated differential effects of consecutive hypoxia and intermittent 24/24-h cycles of H/R on human bronchial epithelial (HBE) cells derived from the same-race and age-matched healthy subjects (i.e., NHBE) and subjects with chronic obstructive pulmonary disease (COPD) (i.e., DHBE). To analyze gene/protein expression during differentiation, both the NHBE and DHBE cells at the 2nd passage were cultured at the air-liquid interface (ALI) in the differentiation medium under normoxia for 3 days, followed by either culturing under hypoxia (1% O₂) for consecutively 9 days and then returning to normoxia for another 9 days, or culturing under 24/24-h cycles of H/R (i.e., 24 h of 1% O₂ followed by 24 h of 21% O₂, repetitively) for 18 days in total, so that all differentiating HBE cells were exposed to hypoxia for a total of 9 days. In both the normal and diseased HBE cells, intermittent H/R significantly increased HIF1A, BMP4, NOTCH1, MKI67, OCT4, and MUC5AC expression, while consecutive hypoxia significantly decreased NKX2-1, NOTCH3, HEY1, CC10, and FOXJ1 expression. Inhibition of HIF1A or NKX2-1 expression by siRNA transfection respectively decreased BMP4/NOTCH1/MKI67/OCT4/MUC5AC and NOTCH3/HEY1/CC10/FOXJ1 expression in the HBE cells cultured under intermittent H/R to the same levels under normoxia. Overexpression of NKX2-1 via cDNA transfection caused more than 2.8-fold increases in NOTCH3, HEY1, and FOXJ1 mRNA levels in the HBE cells cultured under consecutive hypoxia compared to the levels under normoxia. Taken together, our results show for the first time that consecutive hypoxia decreased expression of the co-regulated gene module NOTCH3/HEY1/CC10 and the ciliogenesis-inducing transcription factor gene FOXJ1 via NKX2-1 mRNA downregulation, while intermittent H/R increased expression of the co-regulated gene module BMP4/NOTCH1/MKI67/OCT4 and the predominant airway mucin gene MUC5AC via HIF1A mRNA upregulation.

The Inhibitory Effect of Curcumin on Hypoxia Inducer Factors (Hifs) as a Regulatory Factor in the Growth of Tumor Cells in Breast Cancer Stem-Like Cells

Hypoxia in the microenvironment is related to chemotherapy resistance, tumor progression, and metastasis. Curcumin, as a phenolic compound extracted from the turmeric, has been used as an anti-cancer agent with low toxicity in recent years. Since curcumin has inhibitory activities against hypoxia-inducible factors (HIFs) in several cancers, this study was conducted to examine the effect of curcumin on MCF-7 cells and cancer stem-like cells (CS-LCs) under hypoxic and normoxic conditions. CS-LCs were isolated from MCF-7 cells using the magnet activated cell sorting (MACS) method based on CD₄₄ ⁺/ CD₂₄ ^- surface markers. The effects of curcumin on the viability of MCF-7 cells and CS-LCs were examined in hypoxic and normoxic conditions using the MTT test. The effects of curcumin on apoptosis and cell cycle of CS-LCs and MCF-7 cells were analyzed using flow cytometry. Moreover, the inhibitory effects of curcumin on the levels of HIF-1 and HIF-2α protein in CS-LCs were investigated using the western blot method. Early apoptosis occurred in CSC-LCs more than MCF-7 cells under hypoxic conditions. Flow cytometry assay showed that curcumin caused cell cycle arrest of CSC-LCs and MCF-7 at the G2/M phase under hypoxic conditions while under normoxic conditions, arrest occurred at the G0/G1 phase in MCF-7 cells and at S and G2/M phases in CS-LCs. Based on the results, the curcumin inhibited the expression of HIF-1 by degrading ARNT in CS-LCs.In conclusion, curcumin has inhibitory effects on MCF- 7 cells and CS- LCs and thus may be used as an antitumor agent.

Attenuating hypoxia driven malignant behavior in glioblastoma with a novel hypoxia-inducible factor 2 alpha inhibitor

Hypoxia inducible factor (HIFs) signaling contributes to malignant cell behavior in glioblastoma (GBM). We investigated a novel HIF2α inhibitor, PT2385, both in vitro, with low-passage patient-derived cell lines, and in vivo, using orthotopic models of glioblastoma. We focused on analysis of HIF2α expression in situ, cell survival/proliferation, and survival in brain tumor-bearing mice treated with PT2385 alone and in combination with standard of care chemoradiotherapy. HIF2α expression increased with glioma grade, with over half of GBM specimens HIF2α positive. Staining clustered in perivascular and perinecrotic tumor regions. Cellular phenotype including proliferation, viability, migration/invasion, and also gene expression were not altered after PT2385 treatment. In the animal model, PT2385 single-agent treatment did improve median overall survival compared to placebo (p = 0.04, n = 21) without a bioluminescence correlate (t = 0.67, p = 0.52). No difference in animal survival was seen in combination treatment with radiation (RT)/temozolomide (TMZ)/PT2385 (p = 0.44, n = 10) or mean tumor bioluminescence (t 1.13, p = 0.32). We conclude that HIF2α is a reasonable novel therapeutic target as expressed in the majority of glioblastomas in our cohort. PT2385 as a single-agent was efficacious in vivo, however, an increase in animal survival was not seen with PT2385 in combination with RT/TMZ. Further study for targeting HIF2α as a therapeutic approach in GBM is warranted.

Long non-coding RNA HOXA-AS2 promotes the expression levels of hypoxia-inducible factor-1α and programmed death-ligand 1, and regulates nasopharyngeal carcinoma progression via miR-519

Nasopharyngeal carcinoma (NPC) is a rare malignancy arising from the nasopharyngeal epithelium and belongs to the group of head and neck cancer types, which are usually associated with viral and/or environmental influences, as well as heredity causes. A recent study reported that the long non-coding RNA (lncRNA) HOXA cluster antisense RNA 2 (HOXA-AS2) may be a prognostic biomarker in NPC; however, the specific mechanisms underlying NCP progression are yet to be determined. The aim of the present study was to investigate the biological role of HOXA-AS2 in NPC. In the present study, the gene expression levels of HOXA-AS2, miR-519, hypoxia-inducible factor (HIF-1α) and programmed death-ligand 1 (PD-L1) were detected using reverse transcription-quantitative PCR (RT-qPCR) analysis and western blotting. Bioinformatics analysis and a dual luciferase reporter assay were performed to predict and confirm the direct interactions between HOXA-AS2 and microRNA (miR)-519, as well as between miR-519 and HIF-1α. A MTT assay was used to detect the cell viability, while cell migratory and invasive abilities were assessed using wound healing and Transwell assays. HOXA-AS2 and HIF-1α were found to be significantly upregulated in NPC tumor tissues, as well as in NPC cell lines. The overexpression of HOXA-AS2 significantly enhanced NPC progression, including the cell proliferative, migratory and invasive abilities. HOXA-AS2 was identified to directly bind to miR-519, whereas a miR-519 inhibitor significantly rescued the HOXA-AS2 knockdown-attenuated progression of NPC. Moreover, miR-519 could bind to HIF-1α and PD-L1. Overexpression of HIF-1α and PD-L1 significantly promoted NPC progression and partially recovered the phenotype of NPC cells attenuated by HOXA-AS2 knockdown. In conclusion, the present study demonstrated that HOXA-AS2/miR-519/HIF-1α and/or HOXA-AS2/miR-519/PD-L1 may be a novel mechanism regulating the progression of NPC, which may facilitate the development of targeted clinical therapy.

Metabolic Optimisation of Regulatory T Cells in Transplantation

Regulatory T (Treg) cells expressing the FOXP3 transcription factor are presently under investigation by many teams globally as a cellular therapy to induce tolerance in transplantation. This is primarily due to their immunosuppressive and homeostatic functions. Depending on the type of allograft, Treg cells will need to infiltrate and function in metabolically diverse microenvironments. This means that any resident and circulating Treg cells need to differentially adapt to counter acute or chronic allograft rejection. However, the links between Treg cell metabolism and function are still not entirely delineated. Current data suggest that Treg cells and their effector counterparts have different metabolite dependencies and metabolic programs. These properties could be exploited to optimize intragraft Treg cell function. In this review, we discuss the current paradigms regarding Treg cell metabolism and outline critical intracellular axes that link metabolism and function. Finally, we discuss how this knowledge could be clinically translated for the benefit of transplant patients.

HIF-1α and RKIP: a computational approach for pancreatic cancer therapy

Protein-protein interactions (PPIs) are important biochemical processes that represent a major challenge in modern biology. Current approaches, which include high-throughput screening and computer aided ligand design, have limitations regarding the identification of hit matter. This current investigation focuses on computational study for protein-protein docking of hypoxia inducible factor-1α (HIF-1α), a tumor inducible factor, and Raf-1 kinase inhibitory protein (RKIP), a tumor metastasis suppressor. These are individually crystallized structures of interacting proteins, which interact to generate a conformational space. HIF activity in pancreatic tumors is determined by hypoxia and HIF-1α subunit availability. RKIP can be used as a prognostic indicator in a number of tumors. The interaction of RKIP with HIF-1α protects against pancreatic cancer (PC) metastasis by inhibiting its hypoxia function. We have explored the binding affinity between both the proteins with the HADDOCK (high ambiguity driven protein-protein docking) server, which determined that 158 structures in 11 clusters represent 79.0% of water-refined models. Of the best 10 clusters, the structures of cluster 2 were found to be better, as they had the lowest Z-score. Further supporting HIF-1α-RKIP interaction, pulldown assay has shown dissociation of RKIP from HIF-1α after CoCl2 treatment in both PC cell lines.

Resveratrol binds and inhibits transcription factor HIF-1α in pancreatic cancer

Hypoxia-inducible factor-1 alpha (HIF-1α) has been recognized as one of the essential regulators that is expressed in greater levels in pancreatic cancer (PC) and is connected with poor prognosis. Resveratrol was identified as a natural compound with many biological functions, with anti-inflammatory, antioxidant, and anticancer effects that inhibit the proliferation and progression of PC cells caused by HIF-1α. The current investigation explored the binding affinity and ligand efficacy of resveratrol against HIF-1α using an in silico approach, and the execution of molecular dynamics simulation (MDS) increased the prediction precision of these outcomes. This is the first study that provides an in silico characterization of the interaction between resveratrol and HIF-1α and its spatial structural arrangements in pancreatic cancer therapy, providing an in-depth analysis of their drug target interactions.

Hif-1α Inhibitors Could Successfully Inhibit the Progression of Differentiated Thyroid Cancer in Vitro

Hypoxia-inducible factor (HIF)-1α plays an important role in cancer progression. In various cancers, including thyroid cancer, overexpression of HIF-1α is related to poor prognosis or treatment response. However, few studies have investigated the role of HIF-1α inhibition in thyroid cancer progression. We evaluated the utility of the HIF-1α inhibitor IDF-11774 in vitro utilizing two thyroid cancer cell lines, K1 and BCPAP. Both cell lines were tested to elucidate the effects of IDF-11774 on cell proliferation and migration using soft agar and invasion assays. Here, we found that a reduction of HIF-1α expression in BCPAP cells was observed after treatment with IDF-11774 in a dose-dependent manner. Moreover, cell proliferation, migration, and anchorage-independent growth were effectively inhibited by IDF-11774 in BCPAP cells but not in K1 cells. Additionally, invasion of BCPAP but not K1 cells was controlled with IDF-11774 in a dose-dependent manner. Our findings suggest that promoting the degradation of HIF-1α could be a strategy to manage progression and that HIF-1α inhibitors are potent drugs for thyroid cancer treatment.

Isocitrate dehydrogenase variants in cancer - Cellular consequences and therapeutic opportunities

Abnormal metabolism is common in cancer cells and often correlates with mutations in genes encoding for enzymes involved in small-molecule metabolism. Isocitrate dehydrogenase 1 (IDH1) is the most frequently mutated metabolic gene in cancer. Cancer-associated substitutions in IDH1 and IDH2 impair wild-type production of 2-oxoglutarate and reduced nicotinamide adenine dinucleotide phosphate (NADPH) from isocitrate and oxidised nicotinamide adenine dinucleotide phosphate (NADP⁺ ), and substantially promote the IDH variant catalysed conversion of 2-oxoglutarate to d-2-hydroxyglutarate (d-2HG). Elevated d-2HG is a biomarker for some cancers, and inhibition of IDH1 and IDH2 variants is being pursued as a medicinal chemistry target. We provide an overview of the types of cancer-associated IDH variants, discuss some of the proposed consequences of altered metabolism as a result of elevated d-2HG, summarise therapeutic efforts targeting IDH variants and identify areas for future research.

Mutant p53 induces Golgi tubulo-vesiculation driving a prometastatic secretome

TP53 missense mutations leading to the expression of mutant p53 oncoproteins are frequent driver events during tumorigenesis. p53 mutants promote tumor growth, metastasis and chemoresistance by affecting fundamental cellular pathways and functions. Here, we demonstrate that p53 mutants modify structure and function of the Golgi apparatus, culminating in the increased release of a pro-malignant secretome by tumor cells and primary fibroblasts from patients with Li-Fraumeni cancer predisposition syndrome. Mechanistically, interacting with the hypoxia responsive factor HIF1α, mutant p53 induces the expression of miR-30d, which in turn causes tubulo-vesiculation of the Golgi apparatus, leading to enhanced vesicular trafficking and secretion. The mut-p53/HIF1α/miR-30d axis potentiates the release of soluble factors and the deposition and remodeling of the ECM, affecting mechano-signaling and stromal cells activation within the tumor microenvironment, thereby enhancing tumor growth and metastatic colonization.

Influence of metformin on HIF-1 pathway in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is defined as plasma cells malignancy, developing in the bone marrow. At the beginning of the disease, the malignant plasma cells are dependent on bone marrow microenvironment, providing growth and survival factors. Importantly, the recent studies pointed hypoxia as an important factor promoting progression of MM. In particular, hypoxia-triggered HIF-1 signaling was shown to promote chemoresistance, angiogenesis, invasiveness and induction of immature phenotype, suggesting that strategies targeting HIF-1 may contribute to improvement of anti-myeloma therapies.

METHODS

The Western Blot and RT-PCR techniques were applied to analyze the influence of metformin on HIF-1 pathway in MM cells. To evaluate the effect of metformin on the growth of MM cell lines in normoxic and hypoxic conditions the MTT assay was used. The apoptosis induction in metformin treated hypoxic and normoxic cells was verified by Annexin V/PI staining followed by FACS analysis.

RESULTS

Our results showed, for the first time, that metformin inhibits HIF-1 signaling in MM cells. Moreover, we demonstrated the effect of metformin to be mainly oxygen dependent, since the HIF-1 pathway was not significantly affected by metformin in anoxic conditions as well as after application of hypoxic mimicking compound, CoCl₂. Our data also revealed that metformin triggers the growth arrest without inducing apoptosis in either normoxic or hypoxic conditions.

CONCLUSIONS

Taken together, our study indicates metformin as a promising candidate for developing new treatment strategies exploiting HIF-1 signaling inhibition to enhance the overall anti-MM effect of currently used therapies, that may considerably benefit MM patients.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

Bortezomib and metformin opposingly regulate the expression of hypoxia-inducible factor alpha and the consequent development of chemotherapy-induced painful peripheral neuropathy

Chemotherapy-induced painful peripheral neuropathy is a significant clinical problem that is associated with widely used chemotherapeutics. Unfortunately, the molecular mechanisms by which chemotherapy-induced painful peripheral neuropathy develops have remained elusive. The proteasome inhibitor, bortezomib, has been shown to induce aerobic glycolysis in sensory neurons. This altered metabolic phenotype leads to the extrusion of metabolites which sensitize primary afferents and cause pain. Hypoxia-inducible factor alpha is a transcription factor that is known to reprogram cellular metabolism. Furthermore, hypoxia-inducible factor 1 alpha protein is constantly synthesized and undergoes proteasomal degradation in normal conditions. However, metabolic stress or hypoxia stabilizes the expression of hypoxia-inducible factor 1 alpha leading to the transcription of genes that reprogram cellular metabolism. This study demonstrates that treatment of mice with bortezomib stabilizes the expression of hypoxia-inducible factor 1 alpha. Moreover, knockdown of hypoxia-inducible factor 1 alpha, inhibition of hypoxia-inducible factor 1 alpha binding to its response element, or limiting its translation by using metformin prevent the development of bortezomib-induced neuropathic pain. Strikingly, the blockade of hypoxia-inducible factor 1 alpha expression does not attenuate mechanical allodynia in mice with existing bortezomib-induced neuropathic pain. These results establish the stabilization of hypoxia-inducible factor 1 alpha expression as the molecular mechanism by which bortezomib initiates chemotherapy-induced painful peripheral neuropathy. Crucially, these findings reveal that the initiation and maintenance of bortezomib-induced neuropathic pain are regulated by distinct mechanisms.

Up-regulation of hypoxia-inducible factor antisense as a novel approach to treat ovarian cancer

Ovarian cancer (OC) is estimated to kill ~14,000 women in the United States in 2019. Current chemotherapies to treat OC initially show therapeutic efficacy but frequently drug resistance develops, at which point therapies with alternative targets are needed. Herein, we are describing a novel approach to sensitize these tumors to standard chemotherapies by increasing the transcription of hypoxia-inducible factor antisense.

Methods: Genome-wide Bru-seq analysis was performed to fully capture the nascent transcriptional signature of OC cells treated with the gp130 inhibitor, SC144. In vitro and in vivo analysis, including characterization of hypoxia and select protein expression, combination with standard of care chemotherapy and antitumor efficacy were performed to assess the biological activity of SC144 on induction of hypoxia in OC cells.

Results: Bru-seq analysis of OVCAR8 cells treated with SC144 shows upregulation of hypoxia related genes. In addition, transcription of hypoxia-inducible factor antisense (HIF1A-AS2) was induced that in turn reduced expression of HIF-1α and simultaneously increased expression of NDRG1. Furthermore, we observed decreased protein levels of EGFR, Met, c-Myc, cyclin D1, MMP-2, MMP-9 and TF, and phosphorylation of Src and P130-cas. SC144-induced alterations of HIF-1α and NDRG1 were also confirmed in prostate cancer cells. Ciclopirox olamine (CPX) induces a cellular transcriptional profile comparable to SC144, suggesting a similar cellular mechanism of action between these two compounds. In addition, SC144 sensitized OC cells to olaparib, carboplatin and cisplatin, and shows better in vivo efficacy than CPX.

Conclusion: Induction of hypoxic stress responses through inhibition of gp130 represents a novel approach to design effective anticancer treatments in combination with standard-of-care chemotherapy in OC and the efficacy reported here strongly supports their clinical development.

Hypoxia regulates the differentiation and anti-tumor effector functions of γδT cells in oral cancer

Hypoxia within the tumor microenvironment (TME) is a key factor contributing to immunosuppression in tumors, co-relating with poor treatment outcome and decreased overall survival in advanced oral cancer (OC) patients. Vδ2 is a dominant subset of gamma delta T cells (γδT cells) present in the peripheral blood which exhibits potent anti-tumor cytotoxicity and is evolving as a key player of anti-cancer cellular therapy. However, the fate of γδT cells in hypoxic oral tumors remains elusive. In the present study, we compared the effect of hypoxia (1% O₂ ) and normoxia (21% O₂ ) on the expansion, proliferation, activation status, cytokine secretion and cytotoxicity of γδT cells isolated from OC patients and healthy individuals. Hypoxia-exposed γδT cells exhibited reduced cytotoxicity against oral tumor cells. Our data demonstrated that hypoxia reduces the calcium efflux and the expression of degranulation marker CD107a in γδT cells, which explains the decreased anti-tumor cytotoxicity of γδT cells observed under hypoxia. Hypoxia-exposed γδT cells differentiated to γδT17 [γδ T cells that produce interleukin (IL)-17] cells, which corroborated our observations of increased γδT17 cells observed in the oral tumors. Co-culture of γδT cells with CD8 T cells in the presence of hypoxia showed that programmed cell death ligand 1 (PD-L1)^high γδT cells brought about apoptosis of programmed cell death 1 (PD-1)^high CD8 T cells which could be significantly reversed upon blocking PD-1. Thus, future immunotherapeutic treatment modality for oral cancer may use a combined approach of blocking the PD-1/PD-L1 signaling and targeting hypoxia-inducible factor 1α, which may help in reversing hypoxia-induced immunosuppression.

MicroRNA-1-3p enhances osteoblast differentiation of MC3T3-E1 cells by interacting with hypoxia-inducible factor 1 α inhibitor (HIF1AN)

Studies have proved that miRNAs participate in the regulation of osteoblast differentiation (OD), and abnormal expression of miRNAs is related with various states of OD. In this study, we investigated the role of miRNA-1-3p in OD using MC3T3-E1 cells. BMP2 is used to induce OD of MC3T3-E1 cells. MiRNA-1-3p mimics or miRNA-1-3p inhibitor was transfected to MC3T3-E1 cells with BMP2. The expression levels of miRNA-1-3p were determined by qRT-PCR. The expression of Runx2, OSX, OPN, and OCN was detected by Western blotting. ALP assay was performed to measure alkaline phosphatase activity. Calcium nodules were evaluated by alizarin red staining. Over-expression of hypoxia-inducible factor 1-alpha inhibitor (HIF1AN) was performed and miRNA-1-3p rescue experiments were carried out. Over-expression of miRNA-1-3p promoted osteogenic differentiations and calcifications, as demonstrated by increased ALP, calcification and osteogenic markers. Knock-down of miRNA-1-3p generated the opposite results. HIF1AN was identified to be directly targeted by miRNA-1-3p. Over-expression of HIF1AN suppressed OD and calcifications, and miRNA-1-3p reversed the effect. Our results demonstrated that miRNA-1-3p could enhance OD of MC3T3-E1 cells through interacting with HIF1AN, which might be employed as therapeutic applications for bone formation and regeneration.

Hypoxia-Driven Immune Escape in the Tumor Microenvironment

The tumor microenvironment is a complex ecosystem comprised of many different cell types, abnormal vasculature and immunosuppressive cytokines. The irregular growth kinetics with which tumors grow leads to increased oxygen consumption and, in turn, hypoxic conditions. Hypoxia has been associated with poor clinical outcome, increased tumor heterogeneity, emergence of resistant clones and evasion of immune detection. Additionally, hypoxia-driven cell death pathways have traditionally been thought of as tolerogenic processes. However, as researchers working in the field of immunotherapy continue to investigate and unveil new types of immunogenic cell death (ICD), it has become clear that, in some instances, hypoxia may actually induce ICD within a tumor. In this review, we will discuss hypoxia-driven immune escape that drives poor prognostic outcomes, the ability of hypoxia to induce ICD and potential therapeutic targets amongst hypoxia pathways.

Crosstalk between hydroxytyrosol, a major olive oil phenol, and HIF-1 in MCF-7 breast cancer cells

Olive oil intake has been linked with a lower incidence of breast cancer. Hypoxic microenvironment in solid tumors, such as breast cancer, is known to play a crucial role in cancer progression and in the failure of anticancer treatments. HIF-1 is the foremost effector in hypoxic response, and given that hydroxytyrosol (HT) is one of the main bioactive compounds in olive oil, in this study we deepen into its modulatory role on HIF-1. Our results in MCF-7 breast cancer cells demonstrate that HT decreases HIF-1α protein, probably by downregulating oxidative stress and by inhibiting the PI3K/Akt/mTOR pathway. Strikingly, the expression of HIF-1 target genes does not show a parallel decrease. Particularly, adrenomedullin and vascular endothelial growth factor are up-regulated by high concentrations of HT even in HIF-1α silenced cells, pointing to HIF-1-independent mechanisms of regulation. In fact, we show, by in silico modelling and transcriptional analysis, that high doses of HT may act as an agonist of the aryl hydrocarbon receptor favoring the induction of these angiogenic genes. In conclusion, we suggest that the effect of HT in a hypoxic environment is largely affected by its concentration and involves both HIF-1 dependent and independent mechanisms.

Hypoxia-Inducible Factor Inhibitors Derived from Marine Products Suppress a Murine Model of Neovascular Retinopathy

Neovascular retinal degenerative diseases are the leading causes of blindness in developed countries. Anti-vascular endothelial growth factor (VEGF) therapy is commonly used to treat these diseases currently. However, recent reports indicate that long term suppression of VEGF in the eye is associated with chorioretinal atrophy. Therefore, a physiological amount of VEGF is required for retinal homeostasis. Hypoxia-inducible factor (HIF) is a transcriptional factor upstream of VEGF. We previously reported that HIF regulated pathological angiogenesis in the retina of murine models of oxygen-induced retinopathy and laser-induced choroidal neovascularization. Most of the known HIF inhibitors are anti-cancer agents which may have systemic adverse effects in for clinical use; thus, there is a need for safer and less invasive HIF inhibitors. In this study, we screened marine products, especially fish ingredients, and found that six species of fish had HIF inhibitory effects. Among them, administration of Decapterus tabl ingredients significantly suppressed retinal neovascular tufts by inhibiting HIF expression in a murine oxygen-induced retinopathy model. These results indicate that particular fish ingredients can act as anti-angiogenic agents in retinal neovascularization diseases.

Exosomes are the Driving Force in Preparing the Soil for the Metastatic Seeds: Lessons from the Prostate Cancer

Exosomes are nano-membrane vesicles that various cell types secrete during physiological and pathophysiological conditions. By shuttling bioactive molecules such as nucleic acids, proteins, and lipids to target cells, exosomes serve as key regulators for multiple cellular processes, including cancer metastasis. Recently, microvesicles have emerged as a challenge in the treatment of prostate cancer (PCa), encountered either when the number of vesicles increases or when the vesicles move into circulation, potentially with an ability to induce drug resistance, angiogenesis, and metastasis. Notably, the exosomal cargo can induce the desmoplastic response of PCa-associated cells in a tumor microenvironment (TME) to promote PCa metastasis. However, the crosstalk between PCa-derived exosomes and the TME remains only partially understood. In this review, we provide new insights into the metabolic and molecular signatures of PCa-associated exosomes in reprogramming the TME, and the subsequent promotion of aggressive phenotypes of PCa cells. Elucidating the molecular mechanisms of TME reprogramming by exosomes draws more practical and universal conclusions for the development of new therapeutic interventions when considering TME in the treatment of PCa patients.

Pro- and antitumor effects of mitochondrial reactive oxygen species

In cancer, mitochondrial functions are commonly altered. Directly involved in metabolic reprogramming, mitochondrial plasticity confers to cancer cells a high degree of adaptability to a wide range of stresses and to the harsh tumor microenvironment. Lack of nutrients or oxygen caused by altered perfusion, metabolic needs of proliferating cells, co-option of the microenvironment, control of the immune system, cell migration and metastasis, and evasion of exogenous stress (e.g., chemotherapy) are all, at least in part, influenced by mitochondria. Mitochondria are undoubtedly one of the key contributors to cancer development and progression. Understanding their protumoral (dys)functions may pave the way to therapeutic strategies capable of turning them into innocent entities. Here, we will focus on the production and detoxification of mitochondrial reactive oxygen species (mtROS), on their impact on tumorigenesis (genetic, prosurvival, and microenvironmental effects and their involvement in autophagy), and on tumor metastasis. We will also summarize the latest therapeutic approaches involving mtROS.

Green synthesis and biological evaluation of 6-substituted-2-(2-hydroxy/methoxy phenyl)benzothiazole derivatives as potential antioxidant, antibacterial and antitumor agents

We present a new efficient green synthetic protocol for introduction of substituents to the C-6 position of 2-arylbenzothiazole nuclei. Newly synthesized compounds were designed to study the influence of the hydroxy and methoxy groups on the 2-arylbenzothiazole scaffold, as well as the influence of the type of substituents placed on the C-6 position of benzothiazole moiety on biological activity, including antibacterial, antitumor and antioxidant activity. Modest activity was observed against the tested Gram-positive and Gram-negative bacterial strains for only amidino derivatives 5d and 6d. The tested compounds exhibited moderate to strong antiproliferative activity towards the tumor cell lines tested. The SAR study revealed that the introduction of substituents into the benzene ring of the benzothiazole nuclei is essential for antiproliferative activity, while introduction of the hydroxy group into the 2-aryl moiety of the 2-arybenzothiazole scaffold significantly improved selectivity against tumor cell lines. The observed results revealed several novel 6-substituted-2-arylbenzothiazole compounds, 5b, 5c, 5f and 6f, with strong and selective antiproliferative activity towards HeLa cells in micro and submicromolar concentrations, with the most selective compounds being 6-ammonium-2-(2-hydroxy/methoxyphenyl)benzothiazoles 5f and 6f. The compound 5f bearing the hydroxy group on the 2-arylbenzothiazole core showed the most promising antioxidative activity evaluated by DPPH, ABTS and FRAP in vitro assays. The presence of the amino protonated group attached at the benzothiazole moiety was essential for the antiproliferative and antioxidant activity observed, exerted through a change in the levels of the reactive oxygen species-modulated HIF-1 protein.

The Tumor Vessel Targeting Strategy: A Double-Edged Sword in Tumor Metastasis

Tumor vessels provide essential paths for tumor cells to escape from the primary tumor and form metastatic foci in distant organs. The vessel targeting strategy has been widely used as an important clinical cancer chemotherapeutic strategy for patients with metastatic tumors. Our review introduces the contribution of angiogenesis to tumor metastasis and summarizes the application of Food and Drug Administration (FDA)-approved vessel targeting drugs for metastatic tumors. We recommend the application and mechanisms of vascular targeting drugs for inhibiting tumor metastasis and discuss the risk and corresponding countermeasures after vessel targeting treatment.

Approaches to treat immune hot, altered and cold tumours with combination immunotherapies

Immunotherapies are the most rapidly growing drug class and have a major impact in oncology and on human health. It is increasingly clear that the effectiveness of immunomodulatory strategies depends on the presence of a baseline immune response and on unleashing of pre-existing immunity. Therefore, a general consensus emerged on the central part played by effector T cells in the antitumour responses. Recent technological, analytical and mechanistic advances in immunology have enabled the identification of patients who are more likely to respond to immunotherapy. In this Review, we focus on defining hot, altered and cold tumours, the complexity of the tumour microenvironment, the Immunoscore and immune contexture of tumours, and we describe approaches to treat such tumours with combination immunotherapies, including checkpoint inhibitors. In the upcoming era of combination immunotherapy, it is becoming critical to understand the mechanisms responsible for hot, altered or cold immune tumours in order to boost a weak antitumour immunity. The impact of combination therapy on the immune response to convert an immune cold into a hot tumour will be discussed.