YC-1 inhibits HIF-1 expression in prostate cancer cells: contribution of Akt/NF-kappaB signaling to HIF-1alpha accumulation during hypoxia

Acevaltrate promotes apoptosis and inhibits proliferation by suppressing HIF-1α accumulation in cancer cells

Acevaltrate is a natural product isolated from the roots of Valeriana glechomifolia F.G.Mey. (Valerianaceae) and has been shown to exhibit anti-cancer activity. However, the mechanism by which acevaltrate inhibits tumor growth is not fully understood. We here demonstrated the effect of acevaltrate on hypoxia-inducible factor-1α (HIF-1α) expression. Acevaltrate showed a potent inhibitory activity against HIF-1α induced by hypoxia in various cancer cells. This compound markedly decreased the hypoxia-induced accumulation of HIF-1α protein dose-dependently. Further analysis revealed that acevaltrate inhibited HIF-1α protein synthesis and promoted degradation of HIF-1α protein, without affecting the expression level of HIF-1α mRNA. Moreover, the phosphorylation levels of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K), and eIF4E binding protein-1 (4E-BP1) were significantly suppressed by acevaltrate. In addition, acevaltrate promoted apoptosis and inhibited proliferation, which was potentially mediated by suppression of HIF-1α. We also found that acevaltrate administration inhibited tumor growth in mouse xenograft model. Taken together, these results suggested that acevaltrate was a potent inhibitor of HIF-1α and provided a new insight into the mechanisms of acevaltrate against cancers.

HIF-1 contributes to autophagy activation via BNIP3 to facilitate renal fibrosis in hypoxia in vitro and UUO in vivo

The molecular basis of renal interstitial fibrosis, a major pathological feature of progressive kidney diseases, remains poorly understood. Autophagy has been implicated in renal fibrosis, but whether it promotes or inhibits fibrosis remains controversial. Moreover, it is unclear how autophagy is activated and sustained in renal fibrosis. The present study was designed to address these questions using the in vivo mouse model of unilateral ureteral obstruction and the in vitro model of hypoxia in renal tubular cells. Both models showed the activation of hypoxia-inducible factor-1 (HIF-1) and autophagy along with fibrotic changes. Inhibition of autophagy with chloroquine reduced renal fibrosis in unilateral ureteral obstruction model, whereas chloroquine and autophagy-related gene 7 knockdown decreased fibrotic changes in cultured renal proximal tubular cells, supporting a profibrotic role of autophagy. Notably, pharmacological and genetic inhibition of HIF-1 led to the suppression of autophagy and renal fibrosis in these models. Mechanistically, knock down of BCL2 and adenovirus E1B 19-kDa-interacting protein 3 (BNIP3), a downstream target gene of HIF, decreased autophagy and fibrotic changes during hypoxia in BUMPT cells. Together, these results suggest that HIF-1 may activate autophagy via BNIP3 in renal tubular cells to facilitate the development of renal interstitial fibrosis.NEW & NOTEWORTHY Autophagy has been reported to participate in renal fibrosis, but its role and underlying activation mechanism is unclear. In this study, we report the role of HIF-1 in autophagy activation in models of renal fibrosis and further investigate the underlying mechanism.

Associations between HIFs and tumor immune checkpoints: mechanism and therapy

Hypoxia, which activates a variety of signaling pathways to enhance tumor cell growth and metabolism, is among the primary features of tumor cells. Hypoxia-inducible factors (HIFs) have a substantial impact on a variety of facets of tumor biology, such as epithelial-mesenchymal transition, metabolic reprogramming, angiogenesis, and improved radiation resistance. HIFs induce hypoxia-adaptive responses in tumor cells. Many academics have presented preclinical and clinical research targeting HIFs in tumor therapy, highlighting the potential applicability of targeted HIFs. In recent years, the discovery of numerous pharmacological drugs targeting the regulatory mechanisms of HIFs has garnered substantial attention. Additionally, HIF inhibitors have attained positive results when used in conjunction with traditional oncology radiation and/or chemotherapy, as well as with the very promising addition of tumor immunotherapy. Immune checkpoint inhibitors (CPIs), which are employed in a range of cancer treatments over the past decades, are essential in tumor immunotherapy. Nevertheless, the use of immunotherapy has been severely hampered by tumor resistance and treatment-related toxicity. According to research, HIF inhibitors paired with CPIs may be game changers for multiple malignancies, decreasing malignant cell plasticity and cancer therapy resistance, among other things, and opening up substantial new pathways for immunotherapy drug development. The structure, activation mechanisms, and pharmacological sites of action of the HIF family are briefly reviewed in this work. This review further explores the interactions between HIF inhibitors and other tumor immunotherapy components and covers the potential clinical use of HIF inhibitors in combination with CPIs.

Evodiamine impairs HIF1A histone lactylation to inhibit Sema3A-mediated angiogenesis and PD-L1 by inducing ferroptosis in prostate cancer

Prostate cancer (PCa) is among the most commonly diagnosed solid cancers in male adults. However, most anti-angiogenic therapies and immunotherapies fail to achieve durable remission in advanced PCa. Integrative analysis indicated that Sema3A was negatively correlated with the pathological malignancy and was involved in angiogenesis, cell adhesion, and immune infiltrates in PCa. Sema3A significantly inhibited vascular endothelial growth factor (VEGFA)-induced colony formation, cell proliferation, and PD-L1 expression in PCa cells. Network pharmacological analysis demonstrated that evodiamine, a natural alkaloid compound derived from Evodiae fructus fruits, might regulate Sema3A, lipid metabolism, and monocarboxylic acid transport signaling of PCa. Evodiamine evidently inhibited PCa cell viability in a time-dose-dependent manner. Furthermore, evodiamine impaired angiogenesis by increasing Sema3A expression, and induced ferroptosis by reducing glutathione peroxidase 4 (GPX4) expression, which could be reversed by the ferroptosis blocker ferrostatin-1. Lactate treatment increased hypoxia-inducible factor (HIF)-1α and PD-L1 expressions while restricting Sema3A expression in PCa cells, which could be reversed by silencing monocarboxylate transporter 4 (MCT4) expression. Moreover, evodiamine markedly blocked lactate-induced angiogenesis by restricting histone lactylation and expression of HIF1A in PCa cells, further enhancing Sema3A transcription while inhibiting that of PD-L1. In vivo, evodiamine remarkably inhibited PCa xenograft growth in nude mice, repressing expressions of HIF1α, H3K18la, GPX4, PD-L1, and proliferation, while hindering angiogenesis by increasing Sema3A expression. Therefore, Sema3A represents an essential antineoplastic biomarker, while evodiamine may act as a metabolic-epigenetic modulator, as well as a promising agent in either PCa anti-angiogenic therapy or immunotherapy.

Efficient targeting of HIF-1α mediated by YC-1 and PX-12 encapsulated niosomes: potential application in colon cancer therapy

A number of molecular biofactors have been documented in pathogenesis and poor prognosis of colorectal cancer (CRC). Among them, the Hypoxia-Inducible Factor (HIF-1a) is frequently reported to become over-expressed, and its targeting could restrict and control a variety of essential hallmarks of CRC. Niosomes are innovative drug delivery vehicles with the encapsulating capacity for co-loading both hydrophilic and hydrophobic drugs at the same time. Also, they can enhance the local accumulation while minimizing the dose and side effects of drugs. YC-1 and PX-12 are two inhibitors of HIF-1a. The purpose of this work was to synthesize dual-loaded YC-1 and PX-12 niosomes to efficiently target HIF-1α in CRC, HT-29 cells. The niosomes were prepared by the thin-film hydration method, then the niosomal formulation of YC-1 and PX-12 (NIO/PX-YC) was developed and optimized by the central composition method (CCD) using the Box-Behnken design in terms of size, polydispersity index (PDI), entrapment efficiency (EE). Also, they are characterized by DLS, FESEM, and TEM microscopy, as well as FTIR spectroscopy. Additionally, entrapment efficiency, in vitro drug release kinetics, and stability were assessed. Cytotoxicity, apoptosis, and cell cycle studies were performed after the treatment of HT-29 cells with NIO/PX-YC. The expression of HIF-1αat both mRNA and protein levels were studied after NIO/PX-YC treatment. The prepared NIO/PX-YC showed a mean particle size of 185 nm with a zeta potential of about-7.10 mv and a spherical morphology. Also, PX-12 and YC-1 represented the entrapment efficiency of about %78 and %91, respectively, with a sustainable and controllable release. The greater effect of NIO/PX-YC than the free state of PX-YC on the cell survival rate, cell apoptosis, and HIF-1α gene/protein expression were detected (p < 0.05). In conclusion, dual loading of niosomes with YC-1 and PX-12 enhanced the effect of drugs on HIF-1α inhibition, thus boosting their anticancer effects.

Adamantaniline Derivatives Target ATP5B to Inhibit Translation of Hypoxia Inducible Factor-1α

Hypoxia inducible factor-1α (HIF-1α) plays a critical role in cellular adaptation to hypoxia and it is a potential therapeutic target for anti-cancer drugs. Applying high-throughput screening, here it is found that HI-101, a small molecule containing an adamantaniline moiety, effectively reduces HIF-1α protein expression. With the compound as a hit, a probe (HI-102) is developed for target identification by affinity-based protein profiling. The catalytic β subunit of mitochondrial FO F1 -ATP synthase, ATP5B, is identified as the binding protein of HI-derivatives. Mechanistically, HI-101 promotes the binding of HIF-1α mRNA to ATP5B, thus inhibiting HIF-1α translation and the following transcriptional activity. Further modifications of HI-101 lead to HI-104, a compound with good pharmacokinetic properties, exhibiting antitumor activity in MHCC97-L mice xenograft model, and HI-105, the most potent compound with an IC50 of 26 nm. The findings provide a new strategy for further developing HIF-1α inhibitors by translational inhibition through ATP5B.

Hypoxia-induced PPFIA4 accelerates the progression of ovarian cancer through glucose metabolic reprogramming

Dysregulated glycolysis promotes growth and metastasis, which is one of the metabolic characteristics of ovarian cancer. Based on bioinformatics analysis, liprin-alpha-4 (PPFIA4) is a gene associated with hypoxia, and we aimed to investigate the potential mechanism of PPFIA4 during the reprogramming of glucose metabolism in ovarian cancer cells. Currently, the cell viability of ovarian cancer cells under the hypoxia treatment was evaluated by CCK-8 assay, and cell migration and invasion were measured by transwell assay and western blot. The effects of hypoxia treatment on glucose uptake, lactate production, extracellular acidification rate (ECAR), adenosine triphosphate (ATP), reactive oxygen species (ROS), Nicotinamide adenine dinucleotide phosphate (NADPH) and its oxidized form NADP + , and oxygen consumption rate (OCR) in ovarian cancer cells were examined. Then PPFIA4 was identified through bioinformatic analysis, and the regulatory effects of PPFIA4 on glucose metabolic reprogramming. Our data suggested that hypoxia enhanced the migration and invasion ability of ovarian cancer cells in vitro, and promoted the glucose metabolic reprogramming of ovarian cancer cells. Ovarian cancer cell viability, migration, and invasion were inhibited after PPFIA4 knockdown. Inhibition of PPFIA4 inhibited hypoxic-induced glucose metabolic reprogramming in ovarian cancer cells. In addition, PPFIA4 was found to bind to hypoxia-inducible factor 1alpha (HIF1A), and HIF1A prominently induced PPFIA4 expression. Collectively, HIF1A mediated upregulation of PPFIA4 and promoted reprogramming of glucose metabolism in ovarian cancer cells. Therefore, PPFIA4 may be a therapeutic target for ovarian cancer intervention.

Targeting HIF-1 for prostate cancer: a synthesis of preclinical evidence

INTRODUCTION

Hypoxia-inducible factor (HIF) mediates multiple intracellular processes that drive cellular metabolism and induce proliferation. Dysregulated HIF expression is associated with oncogenic cellular transformation. Moreover, high HIF levels correlate with tumor aggressiveness and chemoresistance, indicating the vital effect of HIF-1α on tumorigenicity. Currently, widespread in-vitro and in-vivo research is focusing on targeting HIF with drugs that have already been approved for use by the FDA, such as belzutifan, in renal cell carcinoma. HIF inhibition is mostly associated with tumor size reduction; however, drug toxicity remains a challenge.

AREA COVERED

In this review, we focus on the potential of targeting HIF in prostate cancer (PC) and summarize the scientific background of HIF activity in PC. This finding emphasizes the rationale for using HIF as a therapeutic target in this malignancy. We have listed known HIF inhibitors that are being investigated in preclinical studies and their potential as anticancer drugs for PC.

EXPERT OPINION

Although HIF-targeting agents have been investigated for over a decade, their use in therapy-resistant cancers remains relevant and should be explored further. In addition, the use of naturally occurring HIF inhibitors should be considered as an add-on therapy for the currently used regimens.

Advances in antitumor research of HIF-1α inhibitor YC-1 and its derivatives

Generally, hypoxia-inducible factor-1α (HIF-1α) is highly expressed in solid tumors, it plays a key role in the occurrence and development of tumors, hindering cancer treatment in various ways. The antitumor activity and pharmacological mechanism of YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1‑benzyl indazole], an HIF-1α inhibitor, and the design and synthesis of its derivatives have attracted tremendous attention in the field of antitumor research. YC-1 is a potential drug candidate and a lead compound for tumor therapy. Hence, the multifaceted mechanism of action of YC-1 and the structure activity relationship (SAR) of its derivatives are important factors to be considered for the development of HIF-1α inhibitors. Therefore, this review aimed to provide a comprehensive overview of the various antitumor mechanisms of YC-1 in antitumor research and an in-depth summary of the SAR for the development of its derivatives. A full understanding and discussion of these aspects are expected to provide potential ideas for developing novel HIF-1α inhibitors and antitumor drugs belonging to the YC-1 class. The review also highlighted the application prospects of the YC-1 class of potential antitumor candidates, and provided some unique insights about these antitumor agents.

PI3K/AKT pathway promotes keloid fibroblasts proliferation by enhancing glycolysis under hypoxia

Our previous study demonstrated altered glucose metabolism and enhanced phosphorylation of the PI3K/AKT pathway in keloid fibroblasts (KFb) under hypoxic conditions. However, whether the PI3K/AKT pathway influences KFb cell function by regulating glucose metabolism under hypoxic conditions remains unclear. Here, we show that when PI3K/AKT pathway was inactivated with LY294002, the protein expression of glycolytic enzymes decreased, while the amount of mitochondria and mitochondrial membrane potential increased. The key parameters of extracellular acidification rate markedly diminished, and those of oxygen consumption rate significantly increased after inhibition of the PI3K/AKT pathway. When the PI3K/AKT pathway was suppressed, the levels of reactive oxygen species (ROS) and mitochondrial ROS (mitoROS) were significantly increased. Meanwhile, cell proliferation, migration and invasion were inhibited, and apoptosis was increased when the PI3K/AKT pathway was blocked. Additionally, cell proliferation was compromised when KFb were treated with both SC79 (an activator of the PI3K/AKT pathway) and 2-deoxy-d-glucose (an inhibitor of glycolysis), compared with the SC79 group. Moreover, a positive feedback mechanism was demonstrated between the PI3K/AKT pathway and hypoxia-inducible factor-1α (HIF-1α). Our data collectively demonstrated that the PI3K/AKT pathway promotes proliferation and inhibits apoptosis in KFb under hypoxia by regulating glycolysis, indicating that the PI3K/AKT signalling pathway could be a therapeutic target for keloids.

The role of hypoxia on prostate cancer progression and metastasis

Prostate cancer is the second most common cancer diagnosed in men and the fifth-leading cause of cancer death in men worldwide. Like any solid tumor, the hypoxic microenvironment of prostatic cancer drives hypoxia-inducible factors (HIFs) to mediate cell adaptions to hypoxic conditions. HIFs direct different signaling pathways such as PI3K/Akt/mTOR, NOX, and Wnt/β-Catenin to tumor progression depending on the degree of hypoxia. HIFs regulate cytoskeleton protein expression, promoting epithelial-mesenchymal transition (EMT), which occurs when cancer cells lose cell-to-cell adhesions and start invasion and metastasis. Through activating pathways, the hypoxic microenvironment maintains the self-renewal, potency, and anti-apoptotic function of prostate cancer cells and induces tumor metastasis and transformation. These pathways could serve as a potential target for prostate cancer therapy. HIFs increase the expression of androgen receptors on cancer cells maintaining the growth and survival of prostate cancer and the development of its castration resistance. In this review, we elaborate on the role of hypoxia in prostatic cancer pathogenesis and different hypoxia-induced mechanisms.

Aluminum induces neuroinflammation via P2X7 receptor activating NLRP3 inflammasome pathway

INTRODUCTION

Aluminum is everywhere in nature and is a recognized neurotoxicant closely associated with various neurodegenerative diseases. Neuroinflammation occurs in the early stage of neurodegenerative diseases, but the underlying mechanism by which aluminum induces neuroinflammation remains unclear.

MATERIAL AND METHODS

A 3-month subchronic aluminum exposure mouse model was established by drinking water containing aluminum chloride (AlCl₃). Microglia BV2 cells and hippocampal neuron HT22 cells were treated with AlCl₃ in vitro. BBG and YC-1 were used as intervention agents.

RESULTS

Aluminum could activate microglia and increase the level of extracellular ATP, stimulate P2X7 receptor, HIF-1α, activate NLRP3 inflammasome and CASP-1, release more cytokine IL-1β, and induce an inflammatory response in nerve cells. There was a mutual regulatory relationship between P2X7 and HIF-1α at mRNA and protein levels. The co-culture system of BV2-HT22 cells observed that conditioned medium from microglia treated with aluminum could aggravate neuronal morphological damage, inflammatory response and death. While BBG and YC-1 intervention could rescue these injuries to some extent.

CONCLUSION

The P2X7-NLRP3 pathway was involved in aluminum-induced neuroinflammation and injury. P2X7 and HIF-1α might mutually regulate and promote the progression of neuroinflammation, both BBG and YC-1 could relieve it.

Suppression of myeloid PFKFB3-driven glycolysis protects mice from choroidal neovascularization

BACKGROUND AND PURPOSE

Pathological angiogenesis is a major cause of irreversible blindness in individuals with neovascular age-related macular degeneration (nAMD). Macrophages and microglia (MΦ) contribute to aberrant ocular angiogenesis. However, the role of glucose metabolism of MΦ in nAMD is still undefined. Here, we have investigated the involvement of glycolysis, driven by the kinase/phosphatase PFKFB3, in the development of choroidal neovascularization (CNV).

EXPERIMENTAL APPROACH

CNV was induced in mice with laser photocoagulation. Choroid/retinal pigment epithelium (RPE) complexes and MΦ were isolated for analysis by qRT-PCR, western blot, flow cytometry, immunostaining, metabolic measurements and angiogenesis assays.

KEY RESULTS

MΦ accumulated within the CNV of murine nAMD models and expressed high levels of glycolysis-related enzymes and M1/M2 polarization markers. This phenotype of hyper-glycolytic and activated MΦ was replicated in bone marrow-derived macrophages stimulated by necrotic RPE in vitro. Myeloid cell-specific knockout of PFKFB3, a key glycolytic activator, attenuated pathological neovascularization in laser-induced CNV, which was associated with decreased expression of MΦ polarization markers and pro-angiogenic factors, along with decreased sprouting of vessels in choroid/RPE complexes. Mechanistically, necrotic RPE increased PFKFB3-driven glycolysis in macrophages, leading to activation of HIF-1α/HIF-2α and NF-κB, and subsequent induction of M1/M2 markers and pro-angiogenic cytokines, finally promoting macrophage reprogramming towards an angiogenic phenotype to facilitate development of CNV. The PFKFB3 inhibitor AZ67 also inhibited activation of HIF-1α/HIF-2α and NF-κB signalling and almost completely prevented laser-induced CNV in mice.

CONCLUSIONS AND IMPLICATIONS

Modulation of PFKFB3-mediated macrophage glycolysis and activation is a promising strategy for the treatment of nAMD.

Targeting HIF-1α by Natural and Synthetic Compounds: A Promising Approach for Anti-Cancer Therapeutics Development

Advancement in novel target detection using improved molecular cancer biology has opened up new avenues for promising anti-cancer drug development. In the past two decades, the mechanism of tumor hypoxia has become more understandable with the discovery of hypoxia-inducible factor-1α (HIF-1α). It is a major transcriptional regulator that coordinates the activity of various transcription factors and their downstream molecules involved in tumorigenesis. HIF-1α not only plays a crucial role in the adaptation of tumor cells to hypoxia but also regulates different biological processes, including cell proliferation, survival, cellular metabolism, angiogenesis, metastasis, cancer stem cell maintenance, and propagation. Therefore, HIF-1α overexpression is strongly associated with poor prognosis in patients with different solid cancers. Hence, pharmacological targeting of HIF-1α has been considered to be a novel cancer therapeutic strategy in recent years. In this review, we provide brief descriptions of natural and synthetic compounds as HIF-1α inhibitors that have the potential to accelerate anticancer drug discovery. This review also introduces the mode of action of these compounds for a better understanding of the chemical leads, which could be useful as cancer therapeutics in the future.

HIF-1α in Osteoarthritis: From Pathogenesis to Therapeutic Implications

Osteoarthritis is a common age-related joint degenerative disease. Pain, swelling, brief morning stiffness, and functional limitations are its main characteristics. There are still no well-established strategies to cure osteoarthritis. Therefore, better clarification of mechanisms associated with the onset and progression of osteoarthritis is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Chondrocytes exist in a hypoxic environment, and HIF-1α plays a vital role in regulating hypoxic response. HIF-1α responds to cellular oxygenation decreases in tissue regulating survival and growth arrest of chondrocytes. The activation of HIF-1α could regulate autophagy and apoptosis of chondrocytes, decrease inflammatory cytokine synthesis, and regulate the chondrocyte extracellular matrix environment. Moreover, it could maintain the chondrogenic phenotype that regulates glycolysis and the mitochondrial function of osteoarthritis, resulting in a denser collagen matrix that delays cartilage degradation. Thus, HIF-1α is likely to be a crucial therapeutic target for osteoarthritis via regulating chondrocyte inflammation and metabolism. In this review, we summarize the mechanism of hypoxia in the pathogenic mechanisms of osteoarthritis, and focus on a series of therapeutic treatments targeting HIF-1α for osteoarthritis. Further clarification of the regulatory mechanisms of HIF-1α in osteoarthritis may provide more useful clues to developing novel osteoarthritis treatment strategies.

Action Sites and Clinical Application of HIF-1α Inhibitors

Hypoxia-inducible factor-1α (HIF-1α) is widely distributed in human cells, and it can form different signaling pathways with various upstream and downstream proteins, mediate hypoxia signals, regulate cells to produce a series of compensatory responses to hypoxia, and play an important role in the physiological and pathological processes of the body, so it is a focus of biomedical research. In recent years, various types of HIF-1α inhibitors have been designed and synthesized and are expected to become a new class of drugs for the treatment of diseases such as tumors, leukemia, diabetes, and ischemic diseases. This article mainly reviews the structure and functional regulation of HIF-1α, the modes of action of HIF-1α inhibitors, and the application of HIF-1α inhibitors during the treatment of diseases.

Study on the HIF-1α regulated by glycolytic pathways and mitochondrial function in yaks of different altitudes during postmortem aging

The study investigated the glycolysis pathway mediated by hypoxia-inducible factor-1α (HIF-1α) and the mechanism of its regulation. The results indicated that HIF-1α expression initially increased before subsequently decreasing with aging time during postmortem (p < .01). Glucose transporter-1 (GLUT-1), lactate dehydrogenase (LDH), and hexokinase (HK) displayed a similar trend with aging time (p < .01) while pyruvate dehydrogenase kinase 1 (PDK-1) increased gradually within the first 12 hr before decreasing at 24-120 hr. However, after treatment with a HIF-1α inhibitor, no significant differences were observed in the mitochondrial morphology. Furthermore, lactate content decreased, along with LDH, HK, and F0F1-ATP activities as well as GLUT-1 and PDK-1 expression (p < .01). The shear force for all groups also increased during postmortem aging (p < .01), with that of the controls being significantly higher compared with the treatment groups (p < .01). These findings confirmed that, after slaughter, the hypoxic environment within the muscles provided essential conditions for HIF-1α expression, which, in turn, activated the glycolysis pathway by mediating changes in the activities of glycolytic enzymes and mitochondrial function. Moreover, in accelerating glycolysis rate, the expression of HIF-1α further played a negative role in meat tenderization during postmortem aging. This, it was concluded that HIF-1α expression plays a significant role in postmortem yak meat tenderization by regulating the glycolysis pathway. PRATICAL APPLICATIONS: While converting muscle into meat through hypoxic glycolysis during postmortem aging is undeniable, the biochemical mechanism of this process mediated remains quite obscure. However, the meat quality difference which impact muscle regulation mechanism during postmortem aging has not been reported. The study investigated the HIF-1α played a major role in both the glycolytic pathway and as well as meat tenderness during the postmortem aging of yak meat. The glycolysis pathway is mediated by hypoxia-inducible factor-1α (HIF-1α), the mechanism of its regulation, and meat tenderness during the postmortem aging of yak meat.

Chemotherapy: a double-edged sword in cancer treatment

Chemotherapy is a well-known and effective treatment for different cancers; unfortunately, it has not been as efficient in the eradication of all cancer cells as been expected. The mechanism of this failure was not fully clarified, yet. Meanwhile, alterations in the physiologic conditions of the tumor microenvironment (TME) were suggested as one of the underlying possibilities. Chemotherapy drugs can activate multiple signaling pathways and augment the secretion of inflammatory mediators. Inflammation may show two opposite roles in the TME. On the one hand, inflammation, as an innate immune response, tries to suppress tumor growth but on the other hand, it might be not powerful enough to eradicate the cancer cells and even it can provide appropriate conditions for cancer promotion and relapse as well. Therefore, the administration of mild anti-inflammatory drugs during chemotherapy might result in more successful clinical results. Here, we will review and discuss this hypothesis. Most chemotherapy agents are triggers of inflammation in the tumor microenvironment through inducing the production of senescence-associated secretory phenotype (SASP) molecules. Some chemotherapy agents can induce systematic inflammation by provoking TLR4 signaling or triggering IL-1B secretion through the inflammasome pathway. NF-kB and MAPK are key signaling pathways of inflammation and could be activated by several chemotherapy drugs. Furthermore, inflammation can play a key role in cancer development, metastasis and exacerbation.

A gemcitabine-based conjugate with enhanced antitumor efficacy by suppressing HIF-1α expression under hypoxia

Hypoxia is one of the unique features of tumor physiology. Hypoxia inducible factor (HIF-1α), as a major transcription factor in response to hypoxia, has been considered as a promising tumor-specific target for anticancer therapy. The formation of a hypoxic microenvironment in tumors can decrease the curative effect of cytotoxic chemotherapeutic drugs. To promote the antitumor efficacy of chemotherapy by suppressing hypoxia, we designed and prepared a novel gemcitabine-based drug conjugate (GEM-5) containing a HIF-1α inhibitor (YC-1). As expected, GEM-5 showed excellent antiproliferative activity (IC50 = 0.03 μΜ under hypoxia) and remarkably induced the apoptosis of A2780 cells in vitro. Additionally, western blot analysis demonstrated that GEM-5 significantly down-regulated the expression of HIF-1α and up-regulated the expression of tumor suppressor p53. More importantly, GEM-5 effectively inhibited tumor growth in the A2780 xenograft mouse model and significantly ameliorated tumor hypoxia in vivo. This novel, simple, and effective strategy for overcoming tumor hypoxia and enhancing the antitumor effect of chemotherapeutic drugs has great potential in cancer therapy.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug development in stroke

Stroke is an acute cerebrovascular disease caused by sudden rupture of blood vessels in the brain or blockage of blood vessels, which has now become one of the main causes of adult death. During stroke, hypoxia-inducible factor-1 (HIF-1), as an important regulator under hypoxia conditions, is involved in the pathological process of stroke by regulating multi-pathways, such as glucose metabolism, angiogenesis, erythropoiesis, cell survival. However, the roles of HIF-1 in stroke are still controversial, which are related with ischemic time and degree of ischemia. The regulatory mechanisms of HIF-1 in stroke include inflammation, autophagy, oxidative stress, apoptosis and energy metabolism. The potential drugs targeting HIF-1 have attracted more attention, such as HIF-1 inhibitors, HIF-1 stabilizers and natural products. Based on the role of HIF-1 in stroke, HIF-1 is expected to be a potential target for stroke treatment. Resolving when and what interventions for HIF-1 to take during stroke will provide novel strategies for stroke treatment.

Radiation Resistance: A Matter of Transcription Factors

Currently, radiation therapy is one of the standard therapies for cancer treatment. Since the first applications, the field of radiotherapy has constantly improved, both in imaging technologies and from a dose-painting point of view. Despite this, the mechanisms of resistance are still a great problem to overcome. Therefore, a more detailed understanding of these molecular mechanisms will allow researchers to develop new therapeutic strategies to eradicate cancer effectively. This review focuses on different transcription factors activated in response to radiotherapy and, unfortunately, involved in cancer cells’ survival. In particular, ionizing radiations trigger the activation of the immune modulators STAT3 and NF-κB, which contribute to the development of radiation resistance through the up-regulation of anti-apoptotic genes, the promotion of proliferation, the alteration of the cell cycle, and the induction of genes responsible for the Epithelial to Mesenchymal Transition (EMT). Moreover, the ROS-dependent damaging effects of radiation therapy are hampered by the induction of antioxidant enzymes by NF-κB, NRF2, and HIF-1. This protective process results in a reduced effectiveness of the treatment, whose mechanism of action relies mainly on the generation of free oxygen radicals. Furthermore, the previously mentioned transcription factors are also involved in the maintenance of stemness in Cancer Stem Cells (CSCs), a subset of tumor cells that are intrinsically resistant to anti-cancer therapies. Therefore, combining standard treatments with new therapeutic strategies targeted against these transcription factors may be a promising opportunity to avoid resistance and thus tumor relapse.

Inhibition of hypoxia inducible factor 1 by YC-1 attenuates tissue plasminogen activator induced hemorrhagic transformation by suppressing HMGB1/TLR4/NF-κB mediated neutrophil infiltration in thromboembolic stroke rats

Hemorrhagic transformation (HT) is a frequent complication of ischemic stroke after thrombolytic therapy and seriously affects the prognosis of stroke. Due to the limited therapeutic window and hemorrhagic complications, tissue plasminogen activator (t-PA) is underutilized in acute ischemic stroke. Currently, there are no clinically effective drugs to decrease the incidence of t-PA-induced HT. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor that maintains oxygen homeostasis and mediates neuroinflammation under hypoxia. However, the effect of HIF-1 on t-PA-induced HT is not clear. The aim of this study was to investigate the role of HIF-1 in t-PA-induced HT by applying YC-1, an inhibitor of HIF-1. In the present study, we found that HIF-1 expression was significantly increased in ischemic brain tissue after delayed t-PA treatment and was mainly localized in neurons and endothelial cells. Inhibition of HIF-1 by YC-1 improved infarct volume and neurological deficits. YC-1 inhibited matrix metalloproteinase protein expression, increased tight junction protein expression, and ameliorated BBB disruption and the occurrence of HT. Furthermore, YC-1 suppressed the release of inflammatory factors, neutrophil infiltration and the activation of the HMGB1/TLR4/NF-κB signaling pathway. These results demonstrated that inhibition of HIF-1 could protect BBB integrity by suppressing HMGB1/TLR4/NF-κB-mediated neutrophil infiltration, thereby reducing the risk of t-PA-induced HT. Thus, HIF-1 may be a potential therapeutic target for t-PA-induced HT.

Intracellular prostaglandin E2 contributes to hypoxia-induced proximal tubular cell death

Proximal tubular cells (PTC) are particularly vulnerable to hypoxia-induced apoptosis, a relevant factor for kidney disease. We hypothesized here that PTC death under hypoxia is mediated by cyclo-oxygenase (COX-2)-dependent production of prostaglandin E₂ (PGE₂), which was confirmed in human proximal tubular HK-2 cells because hypoxia (1% O₂)-induced apoptosis (i) was prevented by a COX-2 inhibitor and by antagonists of prostaglandin (EP) receptors and (ii) was associated to an increase in intracellular PGE₂ (iPGE₂) due to hypoxia-inducible factor-1α-dependent transcriptional up-regulation of COX-2. Apoptosis was also prevented by inhibitors of the prostaglandin uptake transporter PGT, which indicated that iPGE₂ contributes to hypoxia-induced apoptosis (on the contrary, hypoxia/reoxygenation-induced PTC death was exclusively due to extracellular PGE₂). Thus, iPGE₂ is a new actor in the pathogenesis of hypoxia-induced tubular injury and PGT might be a new therapeutic target for the prevention of hypoxia-dependent lesions in renal diseases.

Activation of hypoxia-inducible factor 1 (Hif-1) enhanced bactericidal effects of macrophages to Mycobacterium tuberculosis

BACKGROUND

Tuberculosis is chronic infection caused by Mycobacterium tuberculosis (M.tb), which infects specifically macrophages. Hif-1, hypoxia-inducible factor-1, was reported to act as master regulator of killing functions in macrophages.

AIM

To investigate whether Hif-1 activation would enhance bactericidal effect of macrophages and anti-tuberculosis effect of chemical reagent.

METHODS

Hif-1 and LC3B were detected in tissues from pulmonary tuberculosis. U937, human monocytic leukemia cell line, was stimulated with PMA and differentiated into macrophages. Cells were pretreated with Hif-1 chemical inhibitor YC-1, stimulated with CoCl₂ (Hif-1 activator), to detect LC3B with Western blot and confocal microscopy. Cells were infected with M. tb H37Rv strain, stimulated with CoCl₂, following rifampine treatment. Expression of autophagy markers was detected using Western blot. IL-6 and TNF-α were detected in cell supernatant with ELISA. Acid-fast staining and CFU assay were performed to evaluate intracellular bacterial load.

RESULTS AND CONCLUSIONS

Hif-1 and LC3B increased in tissues of pulmonary tuberculosis. Hif-1 activation enhanced autophagy in M. tb infected U937 cells and production of IL-6 and TNF-α. Data from acid-fast staining and CFU indicated that Hif-1 activation enhanced anti-tuberculosis effect of rifampine in macrophages. Conclusively, to activate Hif-1 would strengthen bactericidal effect of macrophages, to further enhance anti-tuberculosis effect of chemical reagent.

Revisiting prostate cancer metabolism: From metabolites to disease and therapy

Prostate cancer (PCa), one of the most commonly diagnosed cancers worldwide, still presents important unmet clinical needs concerning treatment. In the last years, the metabolic reprogramming and the specificities of tumor cells emerged as an exciting field for cancer therapy. The unique features of PCa cells metabolism, and the activation of specific metabolic pathways, propelled the use of metabolic inhibitors for treatment. The present work revises the knowledge of PCa metabolism and the metabolic alterations that underlie the development and progression of the disease. A focus is given to the role of bioenergetic sources, namely, glucose, lipids, and glutamine sustaining PCa cell survival and growth. Moreover, it is described as the action of oncogenes/tumor suppressors and sex steroid hormones in the metabolic reprogramming of PCa. Finally, the status of PCa treatment based on the inhibition of metabolic pathways is presented. Globally, this review updates the landscape of PCa metabolism, highlighting the critical metabolic alterations that could have a clinical and therapeutic interest.

Hypoxia and Oxygen-Sensing Signaling in Gene Regulation and Cancer Progression

Oxygen homeostasis regulation is the most fundamental cellular process for adjusting physiological oxygen variations, and its irregularity leads to various human diseases, including cancer. Hypoxia is closely associated with cancer development, and hypoxia/oxygen-sensing signaling plays critical roles in the modulation of cancer progression. The key molecules of the hypoxia/oxygen-sensing signaling include the transcriptional regulator hypoxia-inducible factor (HIF) which widely controls oxygen responsive genes, the central members of the 2-oxoglutarate (2-OG)-dependent dioxygenases, such as prolyl hydroxylase (PHD or EglN), and an E3 ubiquitin ligase component for HIF degeneration called von Hippel–Lindau (encoding protein pVHL). In this review, we summarize the current knowledge about the canonical hypoxia signaling, HIF transcription factors, and pVHL. In addition, the role of 2-OG-dependent enzymes, such as DNA/RNA-modifying enzymes, JmjC domain-containing enzymes, and prolyl hydroxylases, in gene regulation of cancer progression, is specifically reviewed. We also discuss the therapeutic advancement of targeting hypoxia and oxygen sensing pathways in cancer.

Human recombinant FSH induces chemoresistance in human breast cancer cells via HIF-1α activation†

Breast cancer patients under 40 years of age who are candidate to chemotherapy with alkylating drugs may undergo controlled ovarian stimulation (COS) with recombinant human follicle-stimulating hormone (rhFSH) in order to get fertility preservation by mature oocyte cryostorage. The direct effect(s) of exogenous rhFSH on the chemosensitivity of breast cancer is currently unknown. To clarify this issue, we incubated four different breast cancer cell lines with rhFSH (10 IU/L, 24 h) and then we exposed them to doxorubicin (DOX) or cyclophosphamide (CPA). The effect(s) of rhFSH on human breast cancer cells treated with DOX or CPA was measured in terms of (1) cell viability, (2) cytotoxicity, (3) multidrug resistance (MDR) genes and proteins expression and activities, and (4) hypoxia-inducible factor 1-alpha (HIF-1α) activation. Pretreatment with rhFSH significantly increased the viability of breast cancer cells after treatment with DOX or CPA, and reduced the lactate dehydrogenase leakage and reactive oxygen species production. Moreover, after preincubation with rhFSH, the MDR proteins (Pgp, MPR1, and BCRP) expression and activity resulted upregulated and the HIF-1α pathway activated. In addition, the use of a widely used HIF-1α inhibitor, the 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1), prevented the rhFSH effect on the onset of MDR. Taken together, these observations suggest that a short exposure to rhFSH induces chemoresistance to DOX and CPA in human breast cancer cells via HIF-1α activation.

A Chinese Herbal Formula Suppresses Colorectal Cancer Migration and Vasculogenic Mimicry Through ROS/HIF-1α/MMP2 Pathway in Hypoxic Microenvironment

Various malignant tumors, including colorectal cancer, have the ability to form functional blood vessels for tumor growth and metastasis. Vasculogenic mimicry (VM) refers to the ability of highly invasive tumor cells to link each other to form vessels, which is associated with poor cancer prognosis. However, the antitumor VM agents are still lacking in the clinic. Astragalus Atractylodes mixture (AAM), a traditional Chinese medicine, has shown to inhibit VM formation; however the exact mechanism is not completely clarified. In this study, we found that HCT-116 and LoVo could form a VM network. Additionally, hypoxia increases the intracellular reactive oxygen species (ROS) level and accelerates migration, VM formation in colorectal cancer cells, while N-Acetylcysteine (NAC) could reverse these phenomena. Notably, further mechanical exploration confirmed that the matrix metalloprotease 2 (MMP2) induction is ROS dependent under hypoxic condition. On the basis, we found that AAM could effectively inhibit hypoxia-induced ROS generation, migration, VM formation as well as HIF-1α and MMP2 expression. In vivo, AAM significantly inhibits metastasis of colorectal cancer in murine lung-metastasis model. Taken together, these results verified that AAM effectively inhibits migration and VM formation by suppressing ROS/HIF-1α/MMP2 pathway in colorectal cancer under hypoxic condition, suggesting AAM could serve as a therapeutic agent to inhibit VM formation in human colorectal cancer.

Retinoic acid receptor-beta prevents cisplatin-induced proximal tubular cell death

Cisplatin's toxicity in renal tubular epithelial cells limits the therapeutic efficacy of this antineoplastic drug. In cultured human proximal tubular HK-2 cells (PTC) a prostaglandin uptake transporter (PGT)-dependent increase in intracellular prostaglandin E₂ (iPGE₂) mediates cisplatin's toxicity (i.e. increased cell death and loss of cell proliferation) so that it is prevented by PGT inhibitors. Here we found in cisplatin-treated PTC that 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), a PGT inhibitor, prevented cisplatin's toxicity but not the increase in iPGE₂. Because expression of retinoic acid receptor-β (RAR-β) is dependent on iPGE₂ and because RAR-β is a regulator of cell survival and proliferation, we hypothesized that RAR-β might mediate the protective effect of DIDS against cisplatin's toxicity in PTC. Our results confirmed this hypothesis because: i) protection of PTC by DIDS was abolished by RAR-β antagonist LE-135; ii) DIDS increased the expression of RAR-β in PTC and prevented its decrease in cisplatin-treated PTC but not in cisplatin-treated human cervical adenocarcinoma HeLa cells in which DIDS failed to prevent cisplatin's toxicity; iii) while RAR-β expression decreased in cisplatin-treated PTC, RAR-β over-expression prevented cisplatin's toxicity. RAR-β agonist CH55 or RAR pan-agonist all-trans retinoic acid did not prevent cisplatin's toxicity, which suggests that RAR-β does not protect PTC through activation of gene transcription. In conclusion, RAR-β might be a new player in cisplatin-induced proximal tubular injury and the preservation of its expression in proximal tubules through treatment with DIDS might represent a novel strategy in the prevention of cisplatin's nephrotoxicity without compromising cisplatin's chemotherapeutic effect on cancer cells.

Small molecules targeting HIF-1α pathway for cancer therapy in recent years

Hypoxia is a very important feature of tumors, especially for solid tumors, and it was demonstrated highly relevant with aggressive biology, including anti-apoptosis, vasculogenesis and radiation or chemotherapy resistance. Correlatively, hypoxia-inducible factors 1-α (HIF-1α), which the wildest contribution of hypoxia-inducible factors (HIFs), plays a crucial role in the adaptation of tumor cells to hypoxia via upregulating the transcription of the oncogene and downregulating the transcription of suppressor gene. This review focus on the HIF-1α regulation including hydroxylation and acetylation, growth factors pathway, heat shock proteins(HSPs), and small molecule inhibitors for HIF-1α directly or indirectly.

Chemogenomic study of gemcitabine using Saccharomyces cerevisiae as model cell-molecular insights about chemoresistance

Gemcitabine (GEM) is the drug used as first line to treat pancreatic cancer, one of the most devastating human tumors. This peculiar type of tumor develops resistance to several drugs, including GEM, due to its desmoplastic reaction and other features. The GEM chemoresistance has been investigated at molecular level aiming to find a pathway whose inhibition or activation should overcome it. Through next-generation sequencing was performed a chemogenomic assay of GEM using Saccharomyces cerevisiae as model cell and the results showed that more than 40% of genes related to GEM response in yeast possess unknown or dubious function. We choose two yeast mutants to individually validate the fitness defect results observed by chemogenomic assay, Δhmt1 and Δcsi1, and it was found that in addition to some already described pathways involved in GEM resistance, cells deficient in deneddylation enzyme Cop9 Signalosome Interactor 1 (Csi1p) presented a high sensitivity to GEM. This was confirmed by individual growth analyses of Δcsi1 cells exposed to GEM, and this phenotype was reverted with CSI1 complementation gene. Csi1p is a well-characterized homolog equivalent to human Csn6 subunit of COP9 signalosome (CSN) involved in deneddylation process. We highlighted too that epigenetic alterations, such as methylation mediated by protein arginine methyltransferase 1, play an important role in regulating gemcitabine treatment resistance. Our results point out new unexplored molecular pathways that can be used to overcome GEM resistance: the inhibition of CSN and the arginine methyltransferase activities.

Hypoxic Radioresistance: Can ROS Be the Key to Overcome It?

Radiotherapy is a mainstay treatment for many types of cancer and kills cancer cells via generation of reactive oxygen species (ROS). Incorporating radiation with pharmacological ROS inducers, therefore, has been widely investigated as an approach to enhance aerobic radiosensitization. However, this strategy was overlooked in hypoxic counterpart, one of the most important causes of radiotherapy failure, due to the notion that hypoxic cells are immune to ROS insults because of the shortage of ROS substrate oxygen. Paradoxically, evidence reveals that ROS are produced more in hypoxic than normoxic cells and serve as signaling molecules that render cells adaptive to hypoxia. As a result, hypoxic tumor cells heavily rely on antioxidant systems to sustain the ROS homeostasis. Thereby, they become sensitive to insults that impair the ROS detoxification network, which has been verified in diverse models with or without radiation. Of note, hypoxic radioresistance has been overviewed in different contexts. To the best of our knowledge, this review is the first to systemically summarize the interplay among radiation, hypoxia, and ROS, and to discuss whether perturbation of ROS homeostasis could provide a new avenue to tackle hypoxic radioresistance.

Rg3 inhibits gemcitabine-induced lung cancer cell invasiveness through ROS-dependent, NF-κB- and HIF-1α-mediated downregulation of PTX3

PTX3, a member of the long pentraxin subfamily, associated with innate immunity is indispensable for resistance to some cancer. Gemcitabine, an analog of cytosine arabinoside, has shown restrained benefits because of profound chemoresistance. The PTX3 expression on GEM in human lung cancer cells have not yet been clarified; the present study aimed to show reactive oxygen species (ROS) mediatory PTX3 expression through distinct mechanisms. Whereas ginsenoside Rg3 is a herbal medicine with strong antitumor activity. Furthermore, we tested the hypothesis; Rg3 abrogates GEM-induced production of ROS-mediated activation of Akt and extracellular signal-regulated kinase (ERK) pathways and inhibits nuclear piling-up of nuclear factor kappa B (NF-κB) and HIF-1α. On the basis of time and dose-dependent manner, our data demonstrated that GEM-induced PTX3 expression was dependent on ROS generation as it was abrogated by pretreatment of lung cancer cells with the free radical scavenger N-acetyl-l-cysteine. Our data demonstrated that PTX3 upregulation by GEM correlated with the time-dependent escalation of NF-κB and HIF-1α in the nucleus resulted from phosphorylation-induced degradation of IκBα, whereas HIF-1α upregulation was NF-κB-dependent. Increase in ROS expression in lung cancer cells on GEM treatment preceded the nuclear accumulation of NF-κB and HIF-1α and suppression of ROS diminished these effects. ERK1/2 and Akt activation mediated the effect of ROS on NF-κB and HIF-1α and their pharmacological inhibition suppressed GEM-induced PTX3. Our study findings reinforced the role regarding PTX3 signaling in GEM-induced resistance and pointed toward an unintended and undesired effect of chemotherapy and to get an active regimen; the synergy was associated with NF-κB downregulation in lung cancer.

TLR8-Mediated Metabolic Control of Human Treg Function: A Mechanistic Target for Cancer Immunotherapy

Regulatory T (Treg) cells induce an immunosuppressive microenvironment that is a major obstacle for successful tumor immunotherapy. Dissecting the regulatory mechanisms between energy metabolism and functionality in Treg cells will provide insight toward developing novel immunotherapies against cancer. Here we report that human naturally occurring and tumor-associated Treg cells exhibit distinct metabolic profiles with selectivity for glucose metabolism compared with effector T cells. Treg-mediated accelerated glucose consumption induces cellular senescence and suppression of responder T cells through cross-talk. TLR8 signaling selectively inhibits glucose uptake and glycolysis in human Treg cells, resulting in reversal of Treg suppression. Importantly, TLR8 signaling-mediated reprogramming of glucose metabolism and function in human Treg cells can enhance anti-tumor immunity in vivo in a melanoma adoptive transfer T cell therapy model. Our studies identify mechanistic links between innate signaling and metabolic regulation of human Treg suppression, which may be used as a strategy to advance tumor immunotherapy.

Promoting antitumor efficacy by suppressing hypoxia via nano self-assembly of two irinotecan-based dual drug conjugates having a HIF-1α inhibitor

Conjugated a hydrophobic HIF-1α inhibitor (YC-1) with a hydrophilic anticancer drug, irinotecan (Ir), into one molecular entity, provided a new insight into the design of smart nanodrug delivery systems to hypoxic tumor tissue.

Mn Porphyrin-Based Redox-Active Drugs: Differential Effects as Cancer Therapeutics and Protectors of Normal Tissue Against Oxidative Injury

SIGNIFICANCE

After approximatelty three decades of research, two Mn(III) porphyrins (MnPs), MnTE-2-PyP⁵⁺ (BMX-010, AEOL10113) and MnTnBuOE-2-PyP⁵⁺ (BMX-001), have progressed to five clinical trials. In parallel, another similarly potent metal-based superoxide dismutase (SOD) mimic-Mn(II)pentaaza macrocycle, GC4419-has been tested in clinical trial on application, identical to that of MnTnBuOE-2-PyP⁵⁺-radioprotection of normal tissue in head and neck cancer patients. This clearly indicates that Mn complexes that target cellular redox environment have reached sufficient maturity for clinical applications. Recent Advances: While originally developed as SOD mimics, MnPs undergo intricate interactions with numerous redox-sensitive pathways, such as those involving nuclear factor κB (NF-κB) and nuclear factor E2-related factor 2 (Nrf2), thereby impacting cellular transcriptional activity. An increasing amount of data support the notion that MnP/H₂O₂/glutathione (GSH)-driven catalysis of S-glutathionylation of protein cysteine, associated with modification of protein function, is a major action of MnPs on molecular level.

CRITICAL ISSUES

Differential effects of MnPs on normal versus tumor cells/tissues, which support their translation into clinic, arise from differences in their accumulation and redox environment of such tissues. This in turn results in different yields of MnP-driven modifications of proteins. Thus far, direct evidence for such modification of NF-κB, mitogen-activated protein kinases (MAPK), phosphatases, Nrf2, and endogenous antioxidative defenses was provided in tumor, while indirect evidence shows the modification of NF-κB and Nrf2 translational activities by MnPs in normal tissue.

FUTURE DIRECTIONS

Studies that simultaneously explore differential effects in same animal are lacking, while they are essential for understanding of extremely intricate interactions of metal-based drugs with complex cellular networks of normal and cancer cells/tissues.

The adaptive regulation of thiamine pyrophosphokinase-1 facilitates malignant growth during supplemental thiamine conditions

Supplemental levels of vitamin B1 (thiamine) have been implicated in tumor progression. Tumor cells adaptively up-regulate thiamine transport during hypoxic stress. Upon uptake, thiamine pyrophosphokinase-1 (TPK1) facilitates the rapid phosphorylation of thiamine into thiamine pyrophosphate (TPP). However, the regulation of TPK1 during hypoxic stress is undefined. Understanding how thiamine homeostasis changes during hypoxia will provide critical insight into the malignant advantage supplemental thiamine may provide cancer cells. Using Western blot analysis and RT-PCR, we have demonstrated the post-transcriptional up-regulation of TPK1 in cancer cells following hypoxic exposure. TPK1 expression was also adaptively up-regulated following alterations of redox status by chemotherapeutic and antioxidant treatments. Although TPK1 was functionally up-regulated by hypoxia, HPLC analysis revealed a reduction in intracellular TPP levels. This loss was reversed by treatment with cell-permeable antioxidants and corresponded with reduced ROS production and enhanced cellular proliferation during supplemental thiamine conditions. siRNA-mediated knockdown of TPK1 directly enhanced basal ROS levels and reduced tumor cell proliferation. These findings suggest that the adaptive regulation of TPK1 may be an essential component in the cellular response to oxidative stress, and that during supplemental thiamine conditions its expression may be exploited by tumor cells for a redox advantage contributing to tumor progression.

Salidroside Inhibits Inflammation Through PI3K/Akt/HIF Signaling After Focal Cerebral Ischemia in Rats

Salidroside is being investigated for its therapeutic potential in stroke because it is neuroprotective over an extended therapeutic window of time. In the present study, we investigated the mechanisms underlying the anti-inflammatory effects of salidroside (50 mg/kg intraperitoneally) in rats, given 1 h after reperfusion of a middle cerebral artery that had been occluded for 2 h. After 24 h, we found that salidroside increased the neuronal nuclear protein NeuN and reduced the marker of microglia and macrophages CD11b in the peri-infarct area of the brain. Salidroside also decreased IL-6, IL-1β, TNF-α, CD14, CD44, and iNOs mRNAs. At the same time, salidroside increased the ratio of phosphorylated protein kinase B (p-Akt) to total Akt. The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 prevented this increase in p-Akt and reversed the inhibitory effects of salidroside on CD11b and inflammatory mediators. Salidroside also elevated the protein levels of hypoxia-inducible factor (HIF) subunits HIF1α, HIF2α, HIF3α, and of erythropoietin (EPO). The stimulatory effects of salidroside on HIFα subunits were blocked by LY294002. Moreover, YC-1, a HIF inhibitor, abolished salidroside-mediated increase of HIF1α and prevented the inhibitory effects of salidroside on CD11b and inflammatory mediators. Taken together, our results provide evidence for the first time that all three HIFα subunits and EPO can be regulated by PI3K/Akt in cerebral tissue, and that salidroside entrains this signaling pathway to induce production of HIFα subunits and EPO, one or more of which mediate the anti-inflammatory effects of salidroside after cerebral IRI.

Novel hypoxia-targeting Pt(iv) prodrugs

Novel Pt(iv) prodrugs targeting hypoxia inducible factor HIF-1α were prepared for evaluating their antitumor activity on hypoxic cancer cells for the first time. The resulting Pt(iv) prodrug exhibited effective inhibition on tumor growth in the HCT-116 xenograft mouse model with low toxicity in vivo.

Retracted Article: Down-regulation of Rab10 inhibits hypoxia-induced invasion and EMT in thyroid cancer cells by targeting HIF-1α through the PI3K/Akt pathway

Rab10, a member of the Rab family, is localized to endocytic compartments and serves as a regulator of intracellular vesicle trafficking. Previous studies mainly paid attention to the role of Rab10 in transport. Recently, Rab10 has been reported to be involved in the progression of various cancers. However, the biological functions of Rab10 in thyroid cancer remain unknown. In this study, we demonstrated that Rab10 was highly expressed in thyroid cancer tissues and cell lines. Down-regulation of Rab10 inhibited hypoxia-induced migration, invasion and epithelial–mesenchymal transition (EMT) of thyroid cancer cells. Moreover, HIF-1α and the PI3K/Akt pathway were involved in the inhibitory effect of Rab10 down-regulation on thyroid cancer cell invasion and EMT induced by hypoxia. Taken together, our study provided further evidence to support the role of Rab10 as a therapeutic target for thyroid cancer.

Rab10, a member of the Rab family, is localized to endocytic compartments and serves as a regulator of intracellular vesicle trafficking.

Future potential of osmium complexes as anticancer drug candidates, photosensitizers and organelle-targeted probes

Here we summarize recent progress in the design and application of innovative osmium compounds as anticancer agents with diverse modes of action, as organelle-targeted imaging probes and photosensitizers for photodynamic therapy.

Leptin-induced migration and angiogenesis in rheumatoid arthritis is mediated by reactive oxygen species

Rheumatoid arthritis (RA) is a progressive autoimmune disease affecting the joints. In this study, we investigated the role of the pro‐angiogenic factor leptin in regulating reactive oxygen species (ROS) to promote cell migration and angiogenesis in RA. We showed that leptin triggered RA fibroblast‐like synoviocyte (FLS) migration by increased ROS expression. Additionally, leptin enhanced human umbilical vein endothelial cell (HUVEC) tube formation in a ROS/hypoxia‐inducible factor‐1α‐dependent manner, accompanied by increased production of vascular endothelial growth factor and interleukin (IL)‐6. We also revealed that antagonists of tumor necrosis factor, IL‐6 and IL‐1β down‐regulated ROS production of RA FLS induced by leptin, which subsequently attenuated RA FLS migration and HUVEC tube formation. These findings demonstrated that leptin might play an important role in RA FLS migration and HUVEC angiogenesis.

Low-dose YC-1 combined with glucose and insulin selectively induces apoptosis in hypoxic gastric carcinoma cells by inhibiting anaerobic glycolysis

This study aimed to establish a therapeutic strategy targeting hypoxic cancer cells in gastric carcinoma (GC). YC-1 is a HIF-1α inhibitor, and we revealed that low-dose YC-1 (10 µM) suppressed HIF-1α expression, and induced hypoxia-dependent apoptosis in the GC cell line 58As9. This hypoxia-specific apoptosis induction by YC-1 involved excessive reactive oxygen species (ROS) generation. The apoptotic effect of 10 µM YC-1 was enhanced by additional glucose (G) and insulin (I) treatments. RT-PCR demonstrated that 10 µM YC-1 reduced hypoxia-induced expression of HIF-1α targets involved in anaerobic glycolysis. Metabolic analysis showed that YC-1 shifted glucose metabolism in hypoxic cells from anaerobic glycolysis to oxidative phosphorylation (OXPHOS). Additional GI accelerated membranous GLUT1 translocation, elevating glucose uptake, and increased acetyl-CoA levels, leading to more ROS generation in hypoxic YC-1-treated cells. Finally, we evaluated the anti-cancer effect of low-dose YC-1 (1 mg/kg) + G (2 g/kg) and I (1 unit/3 g G) treatment in xenograft models. YC-1 + GI therapy strongly inhibited tumour growth. Immunohistochemical analysis demonstrated that YC-1 + GI reduced HIF-1α expression and pimonidazole accumulation in tumours. Conversely, YC-1 + GI increased intra-tumoral 8-OHdG and levels of apoptosis markers. Low-dose YC-1 + GI is a unique therapy targeting hypoxic GC cells that generates lethal ROS via forced activation of OXPHOS.

Hypoxia-inducible factor-1α is involved in isoflurane-induced blood-brain barrier disruption in aged rats model of POCD

Prolonged exposure to inhaled anesthetics may lead to postoperative cognitive dysfunction (POCD). Nevertheless, the underlying mechanisms are not known. Hypoxia-inducible factor-1α (HIF-1α) and its target gene vascular endothelial growth factor (VEGF) were shown to be activated by inhaled anesthetics. The aim of the present study was to determine the role of HIF-1α in isoflurane-induced blood-brain barrier (BBB) disruption and resultant cognitive impairment. After a 4-h exposure to 1.5% isoflurane in 20-month-old rats, increases in vascular permeability, and disrupted BBB ultrastructure were accompanied by the degradation of tight junction proteins occludin and collagen type IV in brain blood vessels. Increases in HIF-1α and VEGF proteins and activation of MMP-2 in the hippocampus were also observed in the hippocamp of isoflurane-exposed rats compared with control rats. Pharmacological inhibition of HIF-1α activation by 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) markedly suppressed the expression of HIF-1α, VEGF and MMP-2, and mitigated the severity of BBB disruption.YC-1 pretreatment also significantly attenuated isoflurane-induced cognitive deficits in the Morris water maze task. Overall, our results demonstrate that hippocampal HIF-1α/VEGF signaling seems to be the upstream mechanism of isoflurane-induced cognitive impairment, and provides apotential preventive and therapeutic target for POCD.

Exploiting the cancer niche: Tumor-associated macrophages and hypoxia as promising synergistic targets for nano-based therapy

The tumor microenvironment has been widely exploited as an active participant in tumor progression. Extensive reports have defined the dual role of tumor-associated macrophages (TAMs) in tumor development. The protumoral effect exerted by the M2 phenotype has been correlated with a negative outcome in most solid tumors. The high infiltration of immune cells in the hypoxic cores of advanced solid tumors leads to a chain reaction of stimuli that enhances the expression of protumoral genes, thrives tumor malignancy, and leads to the emergence of drug resistance. Many studies have shown therapeutic targeting systems, solely to TAMs or tumor hypoxia, however, novel therapeutics that target both features are still warranted. In the present review, we discuss the role of hypoxia in tumor development and the clinical outcome of hypoxia-targeted therapeutics, such as hypoxia-inducible factor (HIF-1) inhibitors and hypoxia-activated prodrugs. Furthermore, we review the state-of-the-art of macrophage-based cancer therapy. We thoroughly discuss the development of novel therapeutics that simultaneously target TAMs and tumor hypoxia. Nano-based systems have been highlighted as interesting strategies for dual modality treatments, with somewhat improved tissue extravasation. Such approach could be seen as a promising strategy to overcome drug resistance and enhance the efficacy of chemotherapy in advanced solid and metastatic tumors, especially when exploiting cell-based nanotherapies. Finally, we provide an in-depth opinion on the importance of exploiting the tumor microenvironment in cancer therapy, and how this could be translated to clinical practice.

Anticancer osmium complex inhibitors of the HIF-1α and p300 protein-protein interaction

The hypoxia inducible factor (HIF) pathway has been considered to be an attractive anti-cancer target. One strategy to inhibit HIF activity is through the disruption of the HIF-1α–p300 protein-protein interaction. We report herein the identification of an osmium(II) complex as the first metal-based inhibitor of the HIF-1α–p300 interaction. We evaluated the effect of complex 1 on HIF-1α signaling pathway in vitro and in cellulo by using the dual luciferase reporter assay, co-immunoprecipitation assay, and immunoblot assay. Complex 1 exhibited a dose-dependent inhibition of HRE-driven luciferase activity, with an IC₅₀ value of 1.22 μM. Complex 1 interfered with the HIF-1α–p300 interaction as revealed by a dose-dependent reduction of p300 co-precipitated with HIF-1α as the concentration of complex 1 was increased. Complex 1 repressed the phosphorylation of SRC, AKT and STAT3, and had no discernible effect on the activity of NF-κB. We anticipate that complex 1 could be utilized as a promising scaffold for the further development of more potent HIF-1α inhibitors for anti-cancer treatment.