Hypoxia Induced ER Stress Response as an Adaptive Mechanism in Cancer

Neuroprotective effects of punicalagin and/or micronized zeolite clinoptilolite on manganese-induced Parkinson's disease in a rat model: Involvement of multiple pathways

BACKGROUND

Manganism, a central nervous system dysfunction correlated with neurological deficits such as Parkinsonism, is caused by the substantial collection of manganese chloride (MnCl2) in the brain.

OBJECTIVES

To explore the neuroprotective effects of natural compounds, namely, micronized zeolite clinoptilolite (ZC) and punicalagin (PUN), either individually or in combination, against MnCl2-induced Parkinson's disease (PD).

METHODS

Fifty male albino rats were divided into 5 groups (Gps). Gp I was used as the control group, and the remaining animals received MnCl2 (Gp II-Gp V). Rats in Gps III and IV were treated with ZC and PUN, respectively. Gp V received both ZC and PUN as previously reported for the solo-treated plants.

RESULTS

ZC and/or PUN reversed the depletion of monoamines in the brain and decreased acetyl choline esterase activity, which primarily adjusted the animals' behavior and motor coordination. ZC and PUN restored the balance between glutamate/γ-amino butyric acid content and markedly improved the brain levels of brain-derived neurotrophic factor and nuclear factor erythroid 2-related factor 2/heme oxygenase-1 and decreased glycogen synthase kinase-3 beta activity. ZC and PUN also inhibited inflammatory and oxidative markers, including nuclear factor kappa-light-chain-enhancer of activated B cells, Toll-like receptor 4, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 and caspase-1. Bcl-2-associated X-protein and B-cell leukemia/lymphoma 2 protein (Bcl-2) can significantly modify caspase-3 expression. ZC and/or PUN ameliorated PD in rats by decreasing the levels of endoplasmic reticulum (ER) stress markers (p-protein kinase-like ER kinase (PERK), glucose-regulated protein 78, and C/EBP homologous protein (CHOP)) and enhancing the levels of an autophagy marker (Beclin-1).

DISCUSSION AND CONCLUSION

ZC and/or PUN mitigated the progression of PD through their potential neurotrophic, neurogenic, anti-inflammatory, antioxidant, and anti-apoptotic activities and by controlling ER stress through modulation of the PERK/CHOP/Bcl-2 pathway.

Acid sphingomyelinase inhibition induces cerebral angiogenesis post-ischemia/reperfusion in an oxidative stress-dependent way and promotes endothelial survival by regulating mitochondrial metabolism

Acid sphingomyelinase (ASM) inhibitors are widely used for the treatment of post-stroke depression. They promote neurological recovery in animal stroke models via neurorestorative effects. In a previous study, we found that antidepressants including amitriptyline, fluoxetine, and desipramine increase cerebral angiogenesis post-ischemia/reperfusion (I/R) in an ASM-dependent way. To elucidate the underlying mechanisms, we investigated the effects of the functional ASM inhibitor amitriptyline in two models of I/R injury, that is, in human cerebral microvascular endothelial hCMEC/D3 cells exposed to oxygen-glucose deprivation and in mice exposed to middle cerebral artery occlusion (MCAO). In addition to our earlier studies, we now show that amitriptyline increased mitochondrial reactive oxygen species (ROS) formation in hCMEC/D3 cells and increased ROS formation in the vascular compartment of MCAO mice. ROS formation was instrumental for amitriptyline's angiogenic effects. ROS formation did not result in excessive endothelial injury. Instead, amitriptyline induced a profound metabolic reprogramming of endothelial cells that comprised reduced endothelial proliferation, reduced mitochondrial energy metabolism, reduced endoplasmic reticulum stress, increased autophagy/mitophagy, stimulation of antioxidant responses and inhibition of apoptotic cell death. Specifically, the antioxidant heme oxygenase-1, which was upregulated by amitriptyline, mediated amitriptyline's angiogenic effects. Thus, heme oxygenase-1 knockdown severely compromised angiogenesis and abolished amitriptyline's angiogenic responses. Our data demonstrate that ASM inhibition reregulates a complex network of metabolic and mitochondrial responses post-I/R that contribute to cerebral angiogenesis without compromising endothelial survival.

p53-Mediated Mitochondrial Translocation of EI24 Triggered by ER Stress Plays an Important Role in Arsenic-Induced Liver Damage via Activating Mitochondrial Apoptotic Pathway

Chronic arsenic poisoning is a public health problem worldwide. In addition to skin lesions, the detrimental effect of arsenic poisoning on liver damage is one of the major issues. Our previous studies demonstrated that endoplasmic reticulum (ER) stress and p53 were associated with arsenic-induced liver damage. Literature has shown that EI24 is involved in hepatocyte hypertrophy; however, the underlying role and mechanism in arsenic-induced liver damage have not been fully elucidated. In this study, we explored the role of ER stress, p53, and EI24 as well as the regulatory relationship in arsenic poisoning populations and L-02 cells treated with distinct concentration NaAsO2 (2.5, 5, 10, and 20 μM). Results showed that as with arsenic dose increment, expression levels of ER stress key proteins GRP78, ATF4, and CHOP were significantly enhanced. Additionally, p53 expression in nucleus, p53 phosphorylation at Ser15 and Ser1392, and p53 acetylation at lys382 were significantly increased in NaAsO2-treated L-02 cells. ER stress inhibitor 4-phenylbutyric acid (4-PBA) decreased the expression of p53 phosphorylation at Ser 392, p53 acetylation at lys382, and p53 expression in nucleus. Additionally, in 5 μM NaAsO2 condition, p53 inhibitor pifithrin-α (PFT-α) aggravated 5 μM NaAsO2-induced GRP78, ATF4, and CHOP expressions, cell apoptosis, and protein-SH consumption. But in 20 μM NaAsO2 condition, PFT-α attenuated NaAsO2-induced cell apoptosis. Further results showed that 20 μM NaAsO2 facilitated translocation of EI24 from ER to mitochondrion and interaction with VDAC2, leading to activate mitochondrial apoptotic pathway, but not observed in the 5-μM NaAsO2 group. Moreover, PFT-α and 4-PBA inhibited 20 μM NaAsO2-induced EI24 expression in mitochondrion. Collectively, our results indicated that arsenic induced p53 activation via ER stress, under relatively low NaAsO2 concentration, NaAsO2-triggered p53 activation protected cells from apoptosis by alleviating ER stress. Another finding was that under relatively high NaAsO2 concentration, NaAsO2-activated p53 facilitated EI24 mitochondrial translocation and caused mitochondrial permeability increase, which represented a switch of p53 from a benefit role to pro-apoptosis function in NaAsO2-treated cells. The study contributed to in-depth understanding the mechanism of arsenic-induced liver damage and providing potential clues for following study.

Hypoxia-induced epigenetic regulation of breast cancer progression and the tumour microenvironment

The events that control breast cancer progression and metastasis are complex and intertwined. Hypoxia plays a key role both in oncogenic transformation and in fueling the metastatic potential of breast cancer cells. Here we review the impact of hypoxia on epigenetic regulation of breast cancer, by interfering with multiple aspects of the tumour microenvironment. The co-dependent relationship between oxygen depletion and metabolic shift to aerobic glycolysis impacts on a range of enzymes and metabolites available in the cell, promoting posttranslational modifications of histones and chromatin, and changing the gene expression landscape to facilitate tumour development. Hormone signalling, particularly through ERα, is also tightly regulated by hypoxic exposure, with HIF-1α expression being a prognostic marker for therapeutic resistance in ER+ breast cancers. This highlights the strong need to understand the hypoxia-endocrine signalling axis and exploit it as a therapeutic target. Furthermore, hypoxia has been shown to enhance metastasis in TNBC cells, as well as promoting resistance to taxanes, radiotherapy and even immunotherapy through microRNA regulation and changes in histone packaging. Finally, several other mediators of the hypoxic response are discussed. We highlight a link between ionic dysregulation and hypoxia signalling, indicating a potential connection between HIF-1α and tumoural Na+ accumulation which would be worth further exploration; we present the role of Ca2+ in mediating hypoxic adaptation via chromatin remodelling, transcription factor recruitment and changes in signalling pathways; and we briefly summarise some of the findings regarding vesicle secretion and paracrine induced epigenetic reprogramming upon hypoxic exposure in breast cancer. By summarising these observations, this article highlights the heterogeneity of breast cancers, presenting a series of pathways with potential for therapeutic applications.

LAT1 expression in colorectal cancer cells is unresponsive to HIF-1/2α accumulation under experimental hypoxia

L-type amino acid transporter 1 (LAT1) is upregulated in various cancer types and contributes to disease progression. Previous studies have demonstrated or suggested that hypoxia-inducible factors (HIFs), the key transcription factors in hypoxic responses, control the expression of LAT1 gene in several types of cancer cells. However, this regulatory relationship has not been investigated yet in colorectal cancer (CRC), one of the cancer types in which the increased LAT1 expression holds prognostic significance. In this study, we found that neither LAT1 mRNA nor protein is induced under hypoxic condition (1% O2) in CRC HT-29 cells in vitro, regardless of the prominent HIF-1/2α accumulation and HIFs-dependent upregulation of glucose transporter 1. The hypoxic treatment generally did not increase either the mRNA or protein expression of LAT1 in eight CRC cell lines tested, in contrast to the pronounced upregulation by amino acid restriction. Interestingly, knockdown of von Hippel-Lindau ubiquitin ligase to inhibit the proteasomal degradation of HIFs caused an accumulation of HIF-2α and increased the LAT1 expression in certain CRC cell lines. This study contributes to delineating the molecular mechanisms responsible for the pathological expression of LAT1 in CRC cells, emphasizing the ambiguity of HIFs-dependent transcriptional upregulation of LAT1 across cancer cells.

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's

Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.

Effect of Short-Term Restraint Stress on the Hypothalamic Transcriptome Profiles of Rats with Inherited Stress-Induced Arterial Hypertension (ISIAH) and Normotensive Wistar Albino Glaxo (WAG) Rats

Emotional stress is one of the health risk factors in the modern human lifestyle. Stress exposure can provoke the manifestation of various pathological conditions, one of which is a sharp increase in the blood pressure level. In the present study, we analyzed changes in the transcriptome profiles of the hypothalamus of hypertensive ISIAH and normotensive WAG rats exposed to a single short-term restraint stress (the rat was placed in a tight wire-mesh cage for 2 h). This type of stress can be considered emotional stress. The functional annotation of differentially expressed genes allowed us to identify the most significantly altered biological processes in the hypothalamus of hypertensive and normotensive rats. The study made it possible to identify a group of genes that describe a general response to stress, independent of the rat genotype, as well as a hypothalamic response to stress specific to each strain. The alternatively changing expression of the Npas4 (neuronal PAS domain protein 4) gene, which is downregulated in the hypothalamus of the control WAG rats and induced in the hypothalamus of hypertensive ISIAH rats, is suggested to be the key event for understanding inter-strain differences in the hypothalamic response to stress. The stress-dependent ISIAH strain-specific induction of Fos and Jun gene transcription may play a crucial role in neuronal activation in this rat strain. The data obtained can be potentially useful in the selection of molecular targets for the development of pharmacological approaches to the correction of stress-induced pathologies related to neuronal excitability, taking into account the hypertensive status of the patients.

The brain of fetuses with congenital diaphragmatic hernia shows signs of hypoxic injury with loss of progenitor cells, neurons, and oligodendrocytes

Congenital diaphragmatic hernia (CDH) is a birth defect characterized by incomplete closure of the diaphragm, herniation of abdominal organs into the chest, and compression of the lungs and the heart. Besides complications related to pulmonary hypoplasia, 1 in 4 survivors develop neurodevelopmental impairment, whose etiology remains unclear. Using a fetal rat model of CDH, we demonstrated that the compression exerted by herniated organs on the mediastinal structures results in decreased brain perfusion on ultrafast ultrasound, cerebral hypoxia with compensatory angiogenesis, mature neuron and oligodendrocyte loss, and activated microglia. In CDH fetuses, apoptosis was prominent in the subventricular and subgranular zones, areas that are key for neurogenesis. We validated these findings in the autopsy samples of four human fetuses with CDH compared to age- and sex-matched controls. This study reveals the molecular mechanisms and cellular changes that occur in the brain of fetuses with CDH and creates opportunities for therapeutic targets.

Hypoxia-inducible factor 1α inhibits heat stress-induced pig intestinal epithelial cell apoptosis through eif2α/ATF4/CHOP signaling

Unstoppable global warming and increased frequency of extreme heat leads to human and animals easier to suffer from heat stress (HS), with gastrointestinal abnormalities as one of the initial clinical symptoms. HS induces intestinal mucosal damage owing to intestinal hypoxia and hyperthermia. Hypoxia-inducible factor 1α (HIF-1α) activates numerous genes to mediate cell hypoxic responses; however, its role in HS-treated intestinal mucosa is unknown. This work aimed to explore HIF-1α function and regulatory mechanisms in HS-treated pig intestines. We assigned 10 pigs to control and moderate HS groups. Physical signs, stress, and antioxidant levels were detected, and the intestines were harvested after 72 h of HS treatment to study histological changes and HIF-1α, heat shock protein 90 (HSP90), and prolyl-4-hydroxylase 2 (PHD-2) expression. In addition, porcine intestinal columnar epithelial cells (IPEC-J2) underwent HS treatment (42 °C, 5 % O2) to further explore the functions and regulatory mechanism of HIF-1α. The results of histological examination revealed HS caused intestinal villi damage and increased apoptotic epithelial cell; the expression of HIF-1α and HSP90 increased while PHD-2 showed and opposite trend. Transcriptome sequencing analysis revealed that HS activated HIF-1 signaling. To further explore the role of HIF-1α on HS induced IPEC-J2 apoptosis, the HIF-1α was interfered and overexpression respectively, and the result confirmed that HIF-1α could inhibited cell apoptosis under HS. Furthermore, HS-induced apoptosis depends on eukaryotic initiation factor 2 alpha (eif2α)/activating transcription factor 4 (ATF4)/CCAAT-enhancer-binding protein homologous protein (CHOP) pathway, and HIF-1α can inhibit this pathway to alleviate IPEC-J2 cell apoptosis. In conclusion, this study suggests that HS can promote intestinal epithelial cell apoptosis and cause pig intestinal mucosal barrier damage; the HIF-1α can alleviate cell apoptosis by inhibiting eif2α/ATF4/CHOP signaling. These results indicate that HIF-1α plays a protective role in HS, and offers a potential target for HS prevention and mitigation.

Ultrastructural and immunohistochemical evaluation of hyperplastic soft tissues surrounding dental implants in fibular jaws

In reconstructive surgery, complications post-fibula free flap (FFF) reconstruction, notably peri-implant hyperplasia, are significant yet understudied. This study analyzed peri-implant hyperplastic tissue surrounding FFF, alongside peri-implantitis and foreign body granulation (FBG) tissues from patients treated at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. Using light microscopy, pseudoepitheliomatous hyperplasia, anucleate and pyknotic prickle cells, and excessive collagen deposition were observed in FFF hyperplastic tissue. Ultrastructural analyses revealed abnormal structures, including hemidesmosome dilation, bacterial invasion, and endoplasmic reticulum (ER) swelling. In immunohistochemical analysis, unfolded protein-response markers ATF6, PERK, XBP1, inflammatory marker NFκB, necroptosis marker MLKL, apoptosis marker GADD153, autophagy marker LC3, epithelial-mesenchymal transition, and angiogenesis markers were expressed variably in hyperplastic tissue surrounding FFF implants, peri-implantitis, and FBG tissues. NFκB expression was higher in peri-implantitis and FBG tissues compared to hyperplastic tissue surrounding FFF implants. PERK expression exceeded XBP1 significantly in FFF hyperplastic tissue, while expression levels of PERK, XBP1, and ATF6 were not significantly different in peri-implantitis and FBG tissues. These findings provide valuable insights into the interconnected roles of ER stress, necroptosis, apoptosis, and angiogenesis in the pathogenesis of oral pathologies, offering a foundation for innovative strategies in dental implant rehabilitation management and prevention.

Multi-omics analysis identifies sex-specific hepatic protein-metabolite networks in yellow catfish (Pelteobagrus fulvidraco) exposed to chronic hypoxia

Hypoxia disrupts the endocrine system of teleosts. The liver plays important roles in the endocrine system, energy storage, and metabolic processes. The aim of this study was to investigate the sex-specific hepatic response of yellow catfish under chronic hypoxia at the multi-omics level. Common hepatic responses in both sexes included the HIF-1 signaling pathway, glycolysis/gluconeogenesis, and steroid biosynthesis. Hypoxia dysregulated primary bile acid biosynthesis, lipid metabolism, and vitellogenin levels in female fish. Endoplasmic reticulum function in females also tended to be disrupted by hypoxia, as evidenced by significantly enriched pathways, including ribosome, protein processing in the endoplasmic reticulum, and RNA degradation. Other pathways, including the TCA cycle, oxidative phosphorylation, and Parkinson's and Huntington's disease, were highly enriched by hypoxia in male fish, suggesting that mitochondrial function was dysregulated. In both sexes of yellow catfish, the cell cycle was arrested and apoptosis was inhibited under chronic hypoxia. Multi-omics suggested that SLC2A5, CD209, LGMN, and NEDD8 served as sex-specific markers in these fish under chronic hypoxia. Our results provide insights into hepatic adaptation to chronic hypoxia and facilitate our understanding of sex-specific responses in fish.

Hypoxia-Inducible Factor-Dependent and Independent Mechanisms Underlying Chemoresistance of Hypoxic Cancer Cells

In hypoxic regions of malignant solid tumors, cancer cells acquire resistance to conventional therapies, such as chemotherapy and radiotherapy, causing poor prognosis in patients with cancer. It is widely recognized that some of the key genes behind this are hypoxia-inducible transcription factors, e.g., hypoxia-inducible factor 1 (HIF-1). Since HIF-1 activity is suppressed by two representative 2-oxoglutarate-dependent dioxygenases (2-OGDDs), PHDs (prolyl-4-hydroxylases), and FIH-1 (factor inhibiting hypoxia-inducible factor 1), the inactivation of 2-OGDD has been associated with cancer therapy resistance by the activation of HIF-1. Recent studies have also revealed the importance of hypoxia-responsive mechanisms independent of HIF-1 and its isoforms (collectively, HIFs). In this article, we collate the accumulated knowledge of HIF-1-dependent and independent mechanisms responsible for resistance of hypoxic cancer cells to anticancer drugs and briefly discuss the interplay between hypoxia responses, like EMT and UPR, and chemoresistance. In addition, we introduce a novel HIF-independent mechanism, which is epigenetically mediated by an acetylated histone reader protein, ATAD2, which we recently clarified.

Targeting Fatty Acid Desaturase I Inhibits Renal Cancer Growth Via ATF3-mediated ER Stress Response

Monounsaturated fatty acids (MUFAs) play a pivotal role in maintaining endoplasmic reticulum (ER) homeostasis, an emerging hallmark of cancer. However, the role of polyunsaturated fatty acid (PUFAs) desaturation in persistent ER stress driven by oncogenic abnormalities remains elusive. Fatty Acid Desaturase 1 (FADS1) is a rate-limiting enzyme controlling the bioproduction of long-chain PUFAs. Our previous research has demonstrated the significant role of FADS1 in cancer survival, especially in kidney cancers. We explored the underlying mechanism in this study. We found that pharmacological inhibition or knockdown of the expression of FADS1 effectively inhibits renal cancer cell proliferation and induces cell cycle arrest. The stable knockdown of FADS1 also significantly inhibits tumor formation in vivo. Mechanistically, we show that while FADS1 inhibition induces ER stress, its expression is also augmented by ER-stress inducers. Notably, FADS1-inhibition sensitized cellular response to ER stress inducers, providing evidence of FADS1's role in modulating the ER stress response in cancer cells. We show that, while FADS1 inhibition-induced ER stress leads to activation of ATF3, ATF3-knockdown rescues the FADS1 inhibition-induced ER stress and cell growth suppression. In addition, FADS1 inhibition results in the impaired biosynthesis of nucleotides and decreases the level of UPD-N-Acetylglucosamine, a critical mediator of the unfolded protein response. Our findings suggest that PUFA desaturation is crucial for rescuing cancer cells from persistent ER stress, supporting FADS1 as a new therapeutic target.

A Study of Alternative TrkA Splicing Identifies TrkAIII as a Novel Potentially Targetable Participant in PitNET Progression

Pituitary neuroendocrine tumors (PitNETs) are generally benign but comprise an aggressive, invasive, therapy-resistant, metastatic subset, underpinning a need for novel therapeutic targets. PitNETs exhibit low mutation rates but are associated with conditions linked to alternative splicing, an alternative oncogene pathway activation mechanism. PitNETs express the neurotrophin receptor TrkA, which exhibits oncogenic alternative TrkAIII splicing in other neuroendocrine tumors. We, therefore, assessed whether TrkAIII splicing represents a potential oncogenic participant in PitNETs. TrkAIII splicing was RT-PCR assessed in 53 PitNETs and TrkA isoform(s) expression and activation were assessed by confocal immunofluorescence. TrkAIII splicing was also compared to HIF1α, HIF2α, SF3B1, SRSF2, U2AF1, and JCPyV large T antigen mRNA expression, Xbp1 splicing, and SF3B1 mutation. TrkAIII splicing was detected in all invasive and most non-invasive PitNETs and was significantly elevated in invasive cases. In PitNET lineages, TrkAIII splicing was significantly elevated in invasive PIT1 PitNETs and high in invasive and non-invasive SF1 and TPIT lineages. Immunoreactivity consistent with TrkAIII activation characterized PitNET expressing TrkAIII mRNA, and invasive Pit1 PitNETs exhibited elevated HIF2α expression. TrkAIII splicing did not associate with SF3B1 mutations, altered SF3B1, SRSF2, and U2AF1 or JCPyV large T antigen expression, or Xbp1 splicing. Therefore, TrkAIII splicing is common in PitNETs, is elevated in invasive, especially PIT1 tumors, can result in intracellular TrkAIII activation, and may involve hypoxia. The data support a role for TrkAIII splicing in PitNET pathogenesis and progression and identify TrkAIII as a novel potential target in refractory PitNETs.

The lipid droplet in cancer: From being a tumor-supporting hallmark to clinical therapy

INTRODUCTION

Abnormal lipid metabolism, one of the hallmarks in cancer, has gradually emerged as a novel target for cancer treatment. As organelles that store and release excess lipids, lipid droplets (LDs) resemble "gears" and facilitate cancer development in the body.

AIM

This review discusses the life cycle of LDs, the relationship between abnormal LDs and cancer hallmarks, and the application of LDs in theragnostic and clinical contexts to provide a contemporary understanding of the role of LDs in cancer.

METHODS

A systematic literature search was conducted in PubMed and SPORTDiscus. Retrieve and summarize clinical trials of drugs that target proteins associated with LD formation using the Clinical Trials website. Create a schematic diagram of lipid droplets in the tumor microenvironment using Adobe Illustrator.

CONCLUSION

As one of the top ten hallmarks of cancer, abnormal lipid metabolism caused by excessive generation of LDs interrelates with other hallmarks. The crosstalk between excessive LDs and intracellular free fatty acids (FFAs) promotes an inflammatory environment that supports tumor growth. Moreover, LDs contribute to cancer metastasis and cell death resistance in vivo. Statins, as HMGCR inhibitors, are promising to be the pioneering commercially available anti-cancer drugs that target LD formation.

Tetralol derivative NNC-55-0396 targets hypoxic cells in the glioblastoma microenvironment: an organ-on-chip approach

Glioblastoma (GBM) is a highly malignant brain tumour characterised by limited treatment options and poor prognosis. The tumour microenvironment, particularly the central hypoxic region of the tumour, is known to play a pivotal role in GBM progression. Cells within this region adapt to hypoxia by stabilising transcription factor HIF1-α, which promotes cell proliferation, dedifferentiation and chemoresistance. In this study we sought to examine the effects of NNC-55-0396, a tetralol compound which overactivates the unfolded protein response inducing apoptosis, using the organ-on-chip technology. We identified an increased sensitivity of the hypoxic core of the chip to NNC, which correlates with decreasing levels of HIF1-α in vitro. Moreover, NNC blocks the macroautophagic process that is unleashed by hypoxia as revealed by increased levels of autophagosomal constituent LC3-II and autophagy chaperone p62/SQSTM1. The specific effects of NNC in the hypoxic microenvironment unveil additional anti-cancer abilities of this compound and further support investigations on its use in combined therapies against GBM.

The role of autophagy in hypoxia-induced radioresistance

Radiotherapy is a widely used treatment modality against cancer, and although survival rates are increasing, radioresistant properties of tumours remain a significant barrier for curative treatment. Tumour hypoxia is one of the main contributors to radioresistance and is common in most solid tumours. Hypoxia is responsible for many molecular changes within the cell which helps tumours to survive under such challenging conditions. These hypoxia-induced molecular changes are predominantly coordinated by the hypoxia inducible factor (HIF) and have been linked with the ability to confer resistance to radiation-induced cell death. To overcome this obstacle research has been directed towards autophagy, a cellular process involved in self degradation and recycling of macromolecules, as HIF plays a large role in its coordination under hypoxic conditions. The role that autophagy has following radiotherapy treatment is conflicted with evidence of both cytoprotective and cytotoxic effects. This literature review aims to explore the intricate relationship between radiotherapy, hypoxia, and autophagy in the context of cancer treatment. It provides valuable insights into the potential of targeting autophagy as a therapeutic strategy to improve the response of hypoxic tumours to radiotherapy.

A perspective on the role of physiological stresses in cancer, diabetes and cognitive disease as environmental diseases

With rapid industrialization, urbanization, and climate change, the impact of environmental factors on human health is becoming increasingly evident and understanding the complex mechanisms involved is vital from a healthcare perspective. Nevertheless, the relationship between physiological stress resulting from environmental stressors and environmental disease is complex and not well understood. Chronic exposure to environmental stressors, such as air and water contaminants, pesticides, and toxic metals, has been recognized as a potent elicitor of physiological responses ranging from systemic inflammation to immune system dysregulation causing or progressing environmental diseases. Conversely, physiological stress can exacerbate susceptibility to environmental diseases. Stress-induced alterations in immune function and hormonal balance may impair the ability to detoxify harmful substances and combat pathogens. Additionally, prolonged stress can impact lifestyle choices, leading to harmful behaviors. Understanding the link between physiological stress and environmental disease requires a systematic, multidisciplinary approach. Addressing this complex relationship necessitates the establishment of a global research network. This perspective discusses the intricate interplay between physiological stress and environmental disease, focusing on common environmental diseases, cancer, diabetes, and cognitive degeneration. Furthermore, we highlight the intricate and reciprocal nature of the connection between physiological stress and these environmental diseases giving a perspective on the current state of knowledge as well as identifying where further information is necessary. Recognizing the role of physiological stress in environmental health outcomes will aid in the development of comprehensive strategies to safeguard public health and promote ecological balance.

Knockdown of NUPR1 inhibits angiogenesis in lung cancer through IRE1/XBP1 and PERK/eIF2α/ATF4 signaling pathways

The stress response molecule nuclear protein‑1 (NUPR1) is essential for the growth of multiple types of human malignant tumor cells. However, the significance of NUPR1 in lung cancer is still not entirely elucidated. Therefore, this study is aimed to explore the function and underlying mechanisms of NUPR1 in lung cancer. NUPR1 mRNA and protein levels in lung cancer cell lines (A549 or H1299 cells) were silenced through siRNA transfection and western blot observed its successful infection efficiency. Then, using tube formation and wound healing experiments, the effects of si-NUPR1 on angiogenesis and migration of human umbilical vein endothelial cells (HUVEC) were examined, respectively, which indicated inhibitory effects on the angiogenesis and migration of HUVEC. Vascular endothelial growth factor A (VEGFA), a vital molecule in angiogenesis, was detected by PCR and western blot assays, manifesting NUPR1 knockdown represses VEGFA expression. Furthermore, the knockdown of NUPR1 may reduce angiogenesis by lowering VEGFA expression through inositol-requiring enzyme 1 (IRE1)/X box binding protein 1 (XBP1) and protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic translation initiation factor 2 A (eIF2α)/recombinant activating transcription factor 4 (ATF4) signaling pathways in A549 or H1299 cells. In conclusion, these findings demonstrated that NUPR1 knockdown inhibits angiogenesis in A549 and H1299 cells through IRE1/XBP1 and PERK/eIF2α/ATF4 signaling pathways, indicating that NUPR1 could represent a novel lung cancer therapeutic target.

Tauroursodeoxycholic Acid Supplementation in In Vitro Culture of Indicine Bovine Embryos: Molecular and Cellular Effects on the In Vitro Cryotolerance

During embryo development, the endoplasmic reticulum (ER) acts as an important site for protein biosynthesis; however, in vitro culture (IVC) can negatively affect ER homeostasis. Therefore, the aim of our study was to evaluate the effects of the supplementation of tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, in the IVC of bovine embryos. Two experiments were carried out: Exp. 1: an evaluation of blastocyst rate, hatching kinetics, and gene expression of hatched embryos after being treated with different concentrations of TUDCA (50, 200, or 1000 μM) in the IVC; Exp. 2: an evaluation of the re-expansion, hatching, and gene expression of hatched embryos previously treated with 200 µM of TUDCA at IVC and submitted to vitrification. There was no increase in the blastocyst and hatched blastocyst rates treated with TUDCA in the IVC. However, embryos submitted to vitrification after treatment with 200 µM of TUDCA underwent an increased hatching rate post-warming together with a down-regulation in the expression of ER stress-related genes and the accumulation of lipids. In conclusion, this work showed that the addition of TUDCA during in vitro culture can improve the cryotolerance of the bovine blastocyst through the putative modulation of ER and oxidative stress.

HIF1α-dependent hypoxia response in myeloid cells requires IRE1α

Cellular adaptation to low oxygen tension triggers primitive pathways that ensure proper cell function. Conditions of hypoxia and low glucose are characteristic of injured tissues and hence successive waves of inflammatory cells must be suited to function under low oxygen tension and metabolic stress. While Hypoxia-Inducible Factor (HIF)-1α has been shown to be essential for the inflammatory response of myeloid cells by regulating the metabolic switch to glycolysis, less is known about how HIF1α is triggered in inflammation. Here, we demonstrate that cells of the innate immune system require activity of the inositol-requiring enzyme 1α (IRE1α/XBP1) axis in order to initiate HIF1α-dependent production of cytokines such as IL1β, IL6 and VEGF-A. Knockout of either HIF1α or IRE1α in myeloid cells ameliorates vascular phenotypes in a model of retinal pathological angiogenesis driven by sterile inflammation. Thus, pathways associated with ER stress, in partnership with HIF1α, may co-regulate immune adaptation to low oxygen.

Recent Developments in Protein Lactylation in PTSD and CVD: Novel Strategies and Targets

In 1938, Corneille Heymans received the Nobel Prize in physiology for discovering that oxygen sensing in the aortic arch and carotid sinus was mediated by the nervous system. The genetics of this process remained unclear until 1991 when Gregg Semenza while studying erythropoietin, came upon hypoxia-inducible factor 1, for which he obtained the Nobel Prize in 2019. The same year, Yingming Zhao found protein lactylation, a posttranslational modification that can alter the function of hypoxia-inducible factor 1, the master regulator of cellular senescence, a pathology implicated in both post-traumatic stress disorder (PTSD) and cardiovascular disease (CVD). The genetic correlation between PTSD and CVD has been demonstrated by many studies, of which the most recent one utilizes large-scale genetics to estimate the risk factors for these conditions. This study focuses on the role of hypertension and dysfunctional interleukin 7 in PTSD and CVD, the former caused by stress-induced sympathetic arousal and elevated angiotensin II, while the latter links stress to premature endothelial cell senescence and early vascular aging. This review summarizes the recent developments and highlights several novel PTSD and CVD pharmacological targets. They include lactylation of histone and non-histone proteins, along with the related biomolecular actors such as hypoxia-inducible factor 1α, erythropoietin, acid-sensing ion channels, basigin, and Interleukin 7, as well as strategies to delay premature cellular senescence by telomere lengthening and resetting the epigenetic clock.

Endoplasmic Reticulum Stress in the Brain Tumor Immune Microenvironment

Immunotherapy has emerged as a powerful strategy for halting cancer progression. However, primary malignancies affecting the brain have been exempt to this success. Indeed, brain tumors continue to portend severe morbidity and remain a globally lethal disease. Extensive efforts have been directed at understanding how tumor cells survive and propagate within the unique microenvironment of the central nervous system (CNS). Cancer genetic aberrations and metabolic abnormalities provoke a state of persistent endoplasmic reticulum (ER) stress that in turn promotes tumor growth, invasion, therapeutic resistance, and the dynamic reprogramming of the infiltrating immune cells. Consequently, targeting ER stress is a potential therapeutic approach. In this work, we provide an overview of how ER stress response is advantageous to brain tumor development, discuss the significance of ER stress in governing antitumor immunity, and put forth therapeutic strategies of regulating ER stress to augment the effect of immunotherapy for primary CNS tumors.

Activation of the integrated stress response (ISR) pathways in response to Ref-1 inhibition in human pancreatic cancer and its tumor microenvironment

Pancreatic cancer or pancreatic ductal adenocarcinoma (PDAC) is characterized by a profound inflammatory tumor microenvironment (TME) with high heterogeneity, metastatic propensity, and extreme hypoxia. The integrated stress response (ISR) pathway features a family of protein kinases that phosphorylate eukaryotic initiation factor 2 (eIF2) and regulate translation in response to diverse stress conditions, including hypoxia. We previously demonstrated that eIF2 signaling pathways were profoundly affected in response to Redox factor-1 (Ref-1) knockdown in human PDAC cells. Ref-1 is a dual function enzyme with activities of DNA repair and redox signaling, responds to cellular stress, and regulates survival pathways. The redox function of Ref-1 directly regulates multiple transcription factors including HIF-1α, STAT3, and NF-κB, which are highly active in the PDAC TME. However, the mechanistic details of the crosstalk between Ref-1 redox signaling and activation of ISR pathways are unclear. Following Ref-1 knockdown, induction of ISR was observed under normoxic conditions, while hypoxic conditions were sufficient to activate ISR irrespective of Ref-1 levels. Inhibition of Ref-1 redox activity increased expression of p-eIF2 and ATF4 transcriptional activity in a concentration-dependent manner in multiple human PDAC cell lines, and the effect on eIF2 phosphorylation was PERK-dependent. Treatment with PERK inhibitor, AMG-44 at high concentrations resulted in activation of the alternative ISR kinase, GCN2 and induced levels of p-eIF2 and ATF4 in both tumor cells and cancer-associated fibroblasts (CAFs). Combination treatment with inhibitors of Ref-1 and PERK enhanced cell killing effects in both human pancreatic cancer lines and CAFs in 3D co-culture, but only at high doses of PERK inhibitors. This effect was completely abrogated when Ref-1 inhibitors were used in combination with GCN2 inhibitor, GCN2iB. We demonstrate that targeting of Ref-1 redox signaling activates the ISR in multiple PDAC lines and that this activation of ISR is critical for inhibition of the growth of co-culture spheroids. Combination effects were only observed in physiologically relevant 3D co-cultures, suggesting that the model system utilized can greatly affect the outcome of these targeted agents. Inhibition of Ref-1 signaling induces cell death through ISR signaling pathways, and combination of Ref-1 redox signaling blockade with ISR activation could be a novel therapeutic strategy for PDAC treatment.

An anticancer Ti(IV) complex increases mitochondrial reactive oxygen species levels in relation with hypoxia and endoplasmic-reticulum stress: A distinct non DNA-related mechanism

PhenolaTi is a promising Ti(IV) anticancer complex, with high stability and cytotoxicity, without notable toxic side-effects. Its cellular mechanism was proposed to relate to ER stress. Herein, we investigated the downstream effects of this mode of action in two cancer cell lines: ovarian carcinoma A2780 and cervical adenocarcinoma HeLa. First, although Ti(IV) is a non-redox metal, the formation of mitochondrial reactive oxygen species (ROS) was detected with live-cell imaging. Then, we inspected the effect of the mitochondrial ROS on cytotoxicity, using two methods: (a) addition of compounds that either elevate or reduce the mitochondrial glutathione concentration, thus affecting the oxidative state of the cells; and (b) scavenging mitochondrial ROS. Unlike the results observed for cisplatin, neither method influenced the cytotoxicity of phenolaTi, implying that ROS formation was a mere side effect of its activity. Additionally, live cell imaging displayed the hypoxia induced by phenolaTi, which can be associated with ROS formation. Overall, the results support the notion that ER-stress is the main cellular mechanism of phenolaTi, leading to hypoxia and mitochondrial ROS. The distinct mechanism of phenolaTi, which is different from that of cisplatin, combined with its stability and favorable anticancer properties, altogether make it a strong chemotherapeutic drug candidate.

4-PBA inhibits hypoxia-induced lipolysis in rat adipose tissue and lipid accumulation in the liver through regulating ER stress

High-altitude hypoxia may disturb the metabolic modulation and function of both adipose tissue and liver. The endoplasmic reticulum (ER) is a crucial organelle in lipid metabolism and ER stress is closely correlated with lipid metabolism dysfunction. The aim of this study is to elucidate whether the inhibition of ER stress could alleviate hypoxia-induced white adipose tissue (WAT) lipolysis and liver lipid accumulation-mediated hepatic injury. A rat model of high-altitude hypoxia (5500 m) was established using hypobaric chamber. The response of ER stress and lipolysis-related pathways were analyzed in WAT under hypoxia exposure with or without 4-phenylbutyric acid (PBA) treatment. Liver lipid accumulation, liver injury, and apoptosis were evaluated. Hypoxia evoked significant ER stress in WAT, evidenced by increased GRP78, CHOP, and phosphorylation of IRE1α, PERK. Moreover, Lipolysis in perirenal WAT significantly increased under hypoxia, accompanied with increased phosphorylation of hormone-sensitive lipase (HSL) and perilipin. Treatment with 4-PBA, inhibitor of ER stress, effectively attenuated hypoxia-induced lipolysis via cAMP-PKA-HSL/perilipin pathway. In addition, 4-PBA treatment significantly inhibited the increase in fatty acid transporters (CD36, FABP1, FABP4) and ameliorated liver FFA accumulation. 4-PBA treatment significantly attenuated liver injury and apoptosis, which is likely resulting from decreased liver lipid accumulation. Our results highlight the importance of ER stress in hypoxia-induced WAT lipolysis and liver lipid accumulation.

Modulation of SREBP Expression and Fatty Acid Levels by Bacteria-Induced ER Stress Is Mediated by Hemocyanin in Penaeid Shrimp

Many environmental and pathogenic insults induce endoplasmic reticulum (ER) stress in animals, especially in aquatic ecosystems, where these factors are crucial for life. In penaeid shrimp, pathogens and environmental stressors induce hemocyanin expression, but the involvement of hemocyanin in ER stress response is unknown. We demonstrate that in response to pathogenic bacteria (Vibrio parahaemolyticus and Streptococcus iniae), hemocyanin, ER stress proteins (Bip, Xbp1s, and Chop), and sterol regulatory element binding protein (SREBP) are induced to alter fatty acid levels in Penaeus vannamei. Interestingly, hemocyanin interacts with ER stress proteins to modulate SREBP expression, while ER stress inhibition with 4-Phenylbutyric acid or hemocyanin knockdown attenuates the expression of ER stress proteins, SREBP, and fatty acid levels. Contrarily, hemocyanin knockdown followed by tunicamycin treatment (ER stress activator) increased their expression. Thus, hemocyanin mediates ER stress during pathogen challenge, which consequently modulates SREBP to regulate the expression of downstream lipogenic genes and fatty acid levels. Our findings reveal a novel mechanism employed by penaeid shrimp to counteract pathogen-induced ER stress.

Identification of thioredoxin domain containing family members' expression pattern and prognostic value in diffuse gliomas via in silico analysis

BACKGROUND

Gliomas are the most prevalent primary tumors of the central nervous system. Their aggressive nature and the obstacles arising during therapy highlights the importance of finding new prognostic markers and therapy targets for gliomas. TXNDC genes are members of the thioredoxin superfamily and were shown to play a role in redox homeostasis, protein folding, electron transfer and also acting as cellular adapters. The well known contribution of these processes in cancer progression prompted us to investigate if TXNDC family members may also play a role in carcinogenesis, in particular diffuse gliomas.

METHODS

The present study used in silico analysis tools GEPIA, UCSC Xena, Gliovis, cBioPortal, and Ivy GAP to evaluate the expression pattern, prognostic value and clinical significance of TXNDC family members in diffuse gliomas.

RESULTS

Our analysis showed that TXNDC family members' expression pattern differ between tumors and healthy tissues and among tumors with different grades. The detailed analysis of TXNDC5 in glioma pathogenesis revealed that TXNDC5 expression is associated with more aggressive clinical and molecular features and poor therapy success both in LGG and GBM samples. Kaplan-Meier survival curves represented a worse prognosis for patients with leveated TXNDC5 levels in LGG and all grade glioma patients. The levels of TXNDC5 was shown to be possibly regulated by hypoxia-ER stress axis and a potential mechanism for TXNDC5-driven glioma progression was found to be extracellular matrix (ECM) production which is known to promote tumor aggressiveness.

CONCLUSIONS

Our results uncovered the previously unknown role of TXNDC family members in glioma pathogenesis and showed that TXNDC5 levels could serve as a predictor of clinical outcome and therapy success and may very well be used for targeted therapy.

Ochratoxin A induces endoplasmic reticulum stress and fibrosis in the kidney via the HIF-1α/miR-155-5p link

Ochratoxin A (OTA) is a ubiquitous fungal toxin found in agricultural products and foods that is toxic to both humans and animals. OTA mainly affects kidney, but the mechanisms underlying OTA-induced nephrotoxicity remain not fully understood. MicroRNA (miRNA) is involved in key cellular processes. The toxic mechanism and regulatory effects of miRNAs on OTA toxicity in kidney, and particularly the role of HIFα-1/miR-155-5p on OTA-caused ER stress and fibrosis, were investigated in this study. OTA induced hypoxia-like conditions such as ER stress and fibrosis in HK-2 cells and renal tissues via modulating HIF-1α, which was followed by regulation of ER stress-related proteins (GRP78 and ATF-4), as well as fibrosis-related markers (fibronectin, α-SMA, and E-cadherin). Notably, a total of 62 miRNAs showed significant differential expression in kidney of OTA-treated mice. Under OTA exposure, HIF-1α enhanced miR-155-5p expression, causing ER stress and fibrosis in HK-2 cells. HIF-1α knockdown decreased OTA-induced miR-155-5p expression as well as ER stress and fibrotic responses, whereas miR-155-5p overexpression restored this. Our data suggest that OTA enhances ER stress and fibrosis in the kidney through upregulating the HIF-1α/miR-155-5p link.

Selective involvement of UGGT variant: UGGT2 in protecting mouse embryonic fibroblasts from saturated lipid-induced ER stress

Secretory proteins and lipids are biosynthesized in the endoplasmic reticulum (ER). The "protein quality control" system (PQC) monitors glycoprotein folding and supports the elimination of terminally misfolded polypeptides. A key component of the PQC system is Uridine diphosphate glucose:glycoprotein glucosyltransferase 1 (UGGT1). UGGT1 re-glucosylates unfolded glycoproteins, to enable the re-entry in the protein-folding cycle and impede the aggregation of misfolded glycoproteins. In contrast, a complementary "lipid quality control" (LQC) system that maintains lipid homeostasis remains elusive. Here, we demonstrate that cytotoxic phosphatidic acid derivatives with saturated fatty acyl chains are one of the physiological substrates of UGGT2, an isoform of UGGT1. UGGT2 produces lipid raft-resident phosphatidylglucoside regulating autophagy. Under the disruption of lipid metabolism and hypoxic conditions, UGGT2 inhibits PERK-ATF4-CHOP-mediated apoptosis in mouse embryonic fibroblasts. Moreover, the susceptibility of UGGT2 KO mice to high-fat diet-induced obesity is elevated. We propose that UGGT2 is an ER-localized LQC component that mitigates saturated lipid-associated ER stress via lipid glucosylation.

Allosteric Inhibition of c-Abl to Induce Unfolded Protein Response and Cell Death in Multiple Myeloma

Endoplasmic reticulum stress activates inositol-requiring enzyme 1α (IRE1α) and protein kinase, R-like endoplasmic reticulum kinase (PERK), the two principal regulators of the unfolded protein response (UPR). In multiple myeloma, adaptive IRE1α signaling is predominantly activated and regulates cell fate along with PERK. Recently, we demonstrated that GNF-2, an allosteric c-Abl inhibitor, rheostatically enhanced IRE1α activity and induced apoptosis through c-Abl conformational changes in pancreatic β cells. Herein, we analyzed whether the pharmacological modulation of c-Abl conformation resulted in anti-myeloma effects. First, we investigated the effects of GNF-2 on IRE1α activity and cell fate, followed by an investigation of the anti-myeloma effects of asciminib, a new allosteric c-Abl inhibitor. Finally, we performed RNA sequencing to characterize the signaling profiles of asciminib. We observed that both GNF-2 and asciminib decreased cell viability and induced XBP1 mRNA splicing in primary human myeloma cells and myeloma cell lines. RNA sequencing identified the induction of UPR- and apoptosis-related genes by asciminib. Asciminib re-localized c-Abl to the endoplasmic reticulum, and its combination with a specific IRE1α inhibitor, KIRA8, enhanced cell death with the reciprocal induction of CHOP mRNA expression. Together, the allosteric inhibition of c-Abl-activated UPR with anti-myeloma effects; this could be a novel therapeutic target for multiple myeloma.

Scleral PERK and ATF6 as targets of myopic axial elongation of mouse eyes

Axial length is the primary determinant of eye size, and it is elongated in myopia. However, the underlying mechanism of the onset and progression of axial elongation remain unclear. Here, we show that endoplasmic reticulum (ER) stress in sclera is an essential regulator of axial elongation in myopia development through activation of both PERK and ATF6 axis followed by scleral collagen remodeling. Mice with lens-induced myopia (LIM) showed ER stress in sclera. Pharmacological interventions for ER stress could induce or inhibit myopia progression. LIM activated all IRE1, PERK and ATF6 axis, and pharmacological inhibition of both PERK and ATF6 suppressed myopia progression, which was confirmed by knocking down above two genes via CRISPR/Cas9 system. LIM dramatically changed the expression of scleral collagen genes responsible for ER stress. Furthermore, collagen fiber thinning and expression of dysregulated collagens in LIM were ameliorated by 4-PBA administration. We demonstrate that scleral ER stress and PERK/ATF6 pathway controls axial elongation during the myopia development in vivo model and 4-PBA eye drop is promising drug for myopia suppression/treatment.

Maternal obesity: new placental paradigms unfolded

The prevalence of maternal obesity is increasing at an alarming rate, and is providing a major challenge for obstetric practice. Adverse effects on maternal and fetal health are mediated by complex interactions between metabolic, inflammatory, and oxidative stress signaling in the placenta. Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are common downstream pathways of cell stress, and there is evidence that this conserved homeostatic response may be a key mediator in the pathogenesis of placental dysfunction. We summarize the current literature on the placental cellular and molecular changes that occur in obese women. A special focus is cast onto placental ER stress in obese pregnancy, which may provide a novel link for future investigation.

MicroRNA-18a regulates the metastatic properties of oral squamous cell carcinoma cells via HIF-1α expression

BACKGROUND

Rapid metastasis of oral squamous cell carcinoma (OSCC) is associated with a poor prognosis and a high mortality rate. However, the molecular mechanisms underlying OSCC metastasis have not been fully elucidated. Although deregulated expression of microRNA (miRNA) has a crucial role in malignant cancer progression, the biological function of miRNA in OSCC progression remains unclear. This study aimed to investigate the function of miRNA-18a in OSCC metastatic regulation via hypoxia-inducible factor 1α (HIF-1α).

METHODS

miRNA-18a-5p (miRNA-18a) expressions in patients with OSCC (n = 39) and in OSCC cell lines (e.g., YD-10B and HSC-2 cells) were analyzed using quantitative real-time polymerase chain reaction. HIF-1α protein expressions in OSCC cells treated with miRNA-18a mimics or combined with cobalt chloride were analyzed using western blotting. The miRNA-18a expression-dependent proliferation and invasion abilities of OSCC cells were analyzed using MTT assay, EdU assay, and a Transwell® insert system.

RESULTS

miRNA-18a expression was significantly lower in OSCC tissue than in the adjacent normal tissue. In OSCC cell lines, HIF-1α expression was significantly decreased by miRNA-18a mimic treatment. Furthermore, the migration and invasion abilities of OSCC cells were significantly decreased by miRNA-18a mimics and significantly increased by the overexpression of HIF-1α under hypoxic conditions relative to those abilities in cells treated only with miRNA-18a mimics.

CONCLUSIONS

miRNA-18a negatively affects HIF-1α expression and inhibits the metastasis of OSCC, thereby suggesting its potential as a therapeutic target for antimetastatic strategies in OSCC.

Metabolic adaption of cancer cells toward autophagy: Is there a role for ER-phagy?

Autophagy is an evolutionary conserved catabolic pathway that uses a unique double-membrane vesicle, called autophagosome, to sequester cytosolic components, deliver them to lysosomes and recycle amino-acids. Essentially, autophagy acts as a cellular cleaning system that maintains metabolic balance under basal conditions and helps to ensure nutrient viability under stress conditions. It is also an important quality control mechanism that removes misfolded or aggregated proteins and mediates the turnover of damaged and obsolete organelles. In this regard, the idea that autophagy is a non-selective bulk process is outdated. It is now widely accepted that forms of selective autophagy are responsible for metabolic rewiring in response to cellular demand. Given its importance, autophagy plays an essential role during tumorigenesis as it sustains malignant cellular growth by acting as a coping-mechanisms for intracellular and environmental stress that occurs during malignant transformation. Cancer development is accompanied by the formation of a peculiar tumor microenvironment that is mainly characterized by hypoxia (oxygen < 2%) and low nutrient availability. Such conditions challenge cancer cells that must adapt their metabolism to survive. Here we review the regulation of autophagy and selective autophagy by hypoxia and the crosstalk with other stress response mechanisms, such as UPR. Finally, we discuss the emerging role of ER-phagy in sustaining cellular remodeling and quality control during stress conditions that drive tumorigenesis.

Rapid Transcriptional Reprogramming Associated With Heat Stress-Induced Unfolded Protein Response in Developing Brassica napus Anthers

Climate change associated increases in the frequency and intensity of extreme temperature events negatively impact agricultural productivity and global food security. During the reproductive phase of a plant's life cycle, such high temperatures hinder pollen development, preventing fertilization, and seed formation. At the molecular level, heat stress-induced accumulation of misfolded proteins activates a signaling pathway called unfolded protein response (UPR) in the endoplasmic reticulum (ER) and the cytoplasm to enhance the protein folding capacity of the cell. Here, we report transcriptional responses of Brassica napus anthers exposed to high temperature for 5, 15, and 30 min to decipher the rapid transcriptional reprogramming associated with the unfolded protein response. Functional classification of the upregulated transcripts highlighted rapid activation of the ER-UPR signaling pathway mediated by ER membrane-anchored transcription factor within 5 min of heat stress exposure. KEGG pathway enrichment analysis also identified "Protein processing in ER" as the most significantly enriched pathway, indicating that the unfolded protein response (UPR) is an immediate heat stress-responsive pathway during B. napus anther development. Five minutes of heat stress also led to robust induction of the cytosolic HSF-HSP heat response network. Our results present a perspective of the rapid and massive transcriptional reprogramming during heat stress in pollen development and highlight the need for investigating the nature and function of very early stress-responsive networks in plant cells. Research focusing on very early molecular responses of plant cells to external stresses has the potential to reveal new stress-responsive gene networks that can be explored further for developing climate change resilient crops.

NF-κB as a regulator of cancer metastasis and therapy response: A focus on epithelial-mesenchymal transition

Metastasis of tumor cells is a complex challenge and significantly diminishes the overall survival and prognosis of cancer patients. The epithelial-to-mesenchymal transition (EMT) is a well-known mechanism responsible for the invasiveness of tumor cells. A number of molecular pathways can regulate the EMT mechanism in cancer cells and nuclear factor-kappaB (NF-κB) is one of them. The nuclear translocation of NF-κB p65 can induce the transcription of several genes involved in EMT induction. The present review describes NF-κB and EMT interaction in cancer cells and their association in cancer progression. Due to the oncogenic role NF-κB signaling, its activation enhances metastasis of tumor cells via EMT induction. This has been confirmed in various cancers including brain, breast, lung and gastric cancers, among others. The ZEB1/2, transforming growth factor-β, and Slug as inducers of EMT undergo upregulation by NF-κB to promote metastasis of tumor cells. After EMT induction driven by NF-κB, a significant decrease occurs in E-cadherin levels, while N-cadherin and vimentin levels undergo an increase. The noncoding RNAs can potentially also function as upstream mediators and modulate NF-κB/EMT axis in cancers. Moreover, NF-κB/EMT axis is involved in mediating drug resistance in tumor cells. Thus, suppressing NF-κB/EMT axis can also promote the sensitivity of cancer cells to chemotherapeutic agents.

Sestrin2 in cancer: a foe or a friend?

Sestrin2 is a conserved antioxidant, metabolism regulator, and downstream of P53. Sestrin2 can suppress oxidative stress and inflammation, thereby preventing the development and progression of cancer. However, Sestrin2 attenuates severe oxidative stress by activating nuclear factor erythroid 2-related factor 2 (Nrf2), thereby enhancing cancer cells survival and chemoresistance. Sestrin2 inhibits endoplasmic reticulum stress and activates autophagy and apoptosis in cancer cells. Attenuation of endoplasmic reticulum stress and augmentation of autophagy hinders cancer development but can either expedite or impede cancer progression under specific conditions. Furthermore, Sestrin2 can vigorously inhibit oncogenic signaling pathways through downregulation of mammalian target of rapamycin complex 1 (mTORC1) and hypoxia-inducible factor 1-alpha (HIF-1α). Conversely, Sestrin2 decreases the cytotoxic activity of T cells and natural killer cells which helps tumor cells immune evasion. Sestrin2 can enhance tumor cells viability in stress conditions such as glucose or glutamine deficiency. Cancer cells can also upregulate Sestrin2 during chemotherapy or radiotherapy to attenuate severe oxidative stress and ER stress, augment autophagy and resist the treatment. Recent studies unveiled that Sestrin2 is involved in the development and progression of several types of human cancer. The effect of Sestrin2 may differ depending on the type of tumor, for instance, several studies revealed that Sestrin2 protects against colorectal cancer, whereas results are controversial regarding lung cancer. Furthermore, Sestrin2 expression correlates with metastasis and survival in several types of human cancer such as colorectal cancer, lung cancer, and hepatocellular carcinoma. Targeted therapy for Sestrin2 or regulation of its expression by new techniques such as non-coding RNAs delivery and vector systems may improve cancer chemotherapy and overcome chemoresistance, metastasis and immune evasion that should be investigated by future trials.

Cancer cells adapt FAM134B/BiP mediated ER-phagy to survive hypoxic stress

In the tumor microenvironment, cancer cells experience hypoxia resulting in the accumulation of misfolded/unfolded proteins largely in the endoplasmic reticulum (ER). Consequently, ER proteotoxicity elicits unfolded protein response (UPR) as an adaptive mechanism to resolve ER stress. In addition to canonical UPR, proteotoxicity also stimulates the selective, autophagy-dependent, removal of discrete ER domains loaded with misfolded proteins to further alleviate ER stress. These mechanisms can favor cancer cell growth, metastasis, and long-term survival. Our investigations reveal that during hypoxia-induced ER stress, the ER-phagy receptor FAM134B targets damaged portions of ER into autophagosomes to restore ER homeostasis in cancer cells. Loss of FAM134B in breast cancer cells results in increased ER stress and reduced cell proliferation. Mechanistically, upon sensing hypoxia-induced proteotoxic stress, the ER chaperone BiP forms a complex with FAM134B and promotes ER-phagy. To prove the translational implication of our mechanistic findings, we identified vitexin as a pharmacological agent that disrupts FAM134B-BiP complex, inhibits ER-phagy, and potently suppresses breast cancer progression in vivo.

Role and regulation of autophagy in cancer

Autophagy is an intracellular self-degradative mechanism which responds to cellular conditions like stress or starvation and plays a key role in regulating cell metabolism, energy homeostasis, starvation adaptation, development and cell death. Numerous studies have stipulated the participation of autophagy in cancer, but the role of autophagy either as tumor suppressor or tumor promoter is not clearly understood. However, mechanisms by which autophagy promotes cancer involves a diverse range of modifications of autophagy associated proteins such as ATGs, Beclin-1, mTOR, p53, KRAS etc. and autophagy pathways like mTOR, PI3K, MAPK, EGFR, HIF and NFκB. Furthermore, several researches have highlighted a context-dependent, cell type and stage-dependent regulation of autophagy in cancer. Alongside this, the interaction between tumor cells and their microenvironment including hypoxia has a great potential in modulating autophagy response in favour to substantiate cancer cell metabolism, self-proliferation and metastasis. In this review article, we highlight the mechanism of autophagy and their contribution to cancer cell proliferation and development. In addition, we discuss about tumor microenvironment interaction and their consequence on selective autophagy pathways and the involvement of autophagy in various tumor types and their therapeutic interventions concentrated on exploiting autophagy as a potential target to improve cancer therapy.

Oxygen control: the often overlooked but essential piece to create better in vitro systems

Variations in oxygen levels play key roles in numerous physiological and pathological processes, but are often not properly controlled in in vitro models, introducing a significant bias in experimental outcomes. Recent developments in microfluidic technology have introduced a paradigm shift by providing new opportunities to better mimic physiological and pathological conditions, which is achieved by both regulating and monitoring oxygen levels at the micrometre scale in miniaturized devices. In this review, we first introduce the nature and relevance of oxygen-dependent pathways in both physiological and pathological contexts. Subsequently, we discuss strategies to control oxygen in microfluidic devices, distinguishing between engineering approaches that operate at the device level during its fabrication and chemical approaches that involve the active perfusion of fluids oxygenated at a precise level or supplemented with oxygen-producing or oxygen-scavenging materials. In addition, we discuss readout approaches for monitoring oxygen levels at the cellular and tissue levels, focusing on electrochemical and optical detection schemes for high-resolution measurements directly on-chip. An overview of different applications in which microfluidic devices have been utilized to answer biological research questions is then provided. In the final section, we provide our vision for further technological refinements of oxygen-controlling devices and discuss how these devices can be employed to generate new fundamental insights regarding key scientific problems that call for emulating oxygen levels as encountered in vivo. We conclude by making the case that ultimately emulating physiological or pathological oxygen levels should become a standard feature in all in vitro cell, tissue, and organ models.

Exosomes in Pathogenesis, Diagnosis, and Treatment of Hepatocellular Carcinoma

Exosomes are extracellular vesicles with a diameter of 30-150 nm that are released by most types of cells and have been confirmed to be involved in many physical and pathological processes, especially in cell to cell communication. Compared with other vesicles, exosomes have a unique double-layer saclike structure that allows them to be present stably in various body fluids, including blood, cerebrospinal fluid, urine, saliva, and serous cavity effusion. The cargoes of exosomes reflect the characteristics of host cells. Due to the nature of hepatocellular carcinoma (HCC) cells, heterogeneity in the bioactive substances usually exist in exosomes. In addition, exosomes can efficiently deliver cargoes to the target cells to exert pathological functions, playing important role in tumor occurrence, development, metastasis, immune regulation, and drug resistance. Previous studies have been shown that exosomes have wide applications in diagnosis and treatment of HCC. In this review, we discuss these recent findings and highlight the significant roles of exosomes in HCC, focusing on the effect and underlying mechanisms of exosomes to regulate HCC progression and the potential clinical value of exosomes as biomarkers and therapeutic targets.

The unfolded protein response: An emerging therapeutic target for pancreatitis and pancreatic ductal adenocarcinoma

Pancreatitis is a debilitating disease involving inflammation and fibrosis of the exocrine pancreas. Recurrent or chronic forms of pancreatitis are a significant risk factor for pancreatic ductal adenocarcinoma. While genetic factors have been identified for both pathologies, environmental stresses play a large role in their etiology. All cells have adapted mechanisms to handle acute environmental stress that alters energy demands. A common pathway involved in the stress response involves endoplasmic reticulum stress and the unfolded protein response (UPR). While rapidly activated by many external stressors, in the pancreas the UPR plays a fundamental biological role, likely due to the high protein demands in acinar cells. Despite this, increased UPR activity is observed in response to acute injury or following exposure to risk factors associated with pancreatitis and pancreatic cancer. Studies in animal and cell cultures models show the importance of affecting the UPR in the context of both diseases, and inhibitors have been developed for several specific mediators of the UPR. Given the importance of the UPR to normal acinar cell function, efforts to affect the UPR in the context of disease must be able to specifically target pathology vs. physiology. In this review, we highlight the importance of the UPR to normal and pathological conditions of the exocrine pancreas. We discuss recent studies suggesting the UPR may be involved in the initiation and progression of pancreatitis and PDAC, as well as contributing to chemoresistance that occurs in pancreatic cancer. Finally, we discuss the potential of targeting the UPR for treatment.

Hypoxia-Induced LncRNA-MIR210HG Promotes Cancer Progression By Inhibiting HIF-1α Degradation in Ovarian Cancer

LncRNA-MIR210HG plays crucial roles in the progression of diverse cancers. However, the expression and function of MIR210HG in ovarian cancer remains unclear. In the present study, we aimed to determine the expression and function of lncRNA-MIR210HG in ovarian cancer under hypoxic conditions. MIR210HG expression in ovarian cancer cells under hypoxic conditions was determined by qPCR analysis, and the distribution was determined by FISH and qPCR analysis based on cell nucleus and cytosol RNA extraction. Epithelial-Mesenchymal Transition (EMT) assay and human umbilical vein endothelial cell-based tube formation and migration assays were employed to determine the potential function of MIR210HG in vitro, followed by establishment of a subcutaneous tumor model in mice. The direct target of MIR210HG was determined by RNA pull-down and western blotting. Furthermore, the expression and clinical correlation of MIR210HG was determined based on malignant tissues from ovarian cancer patients. Our results indicated that MIR210HG was induced by hypoxia, which is HIF-1α dependent and mainly located in the cytosol of ovarian cancer cells. Knockdown of MIR210HG significantly inhibited EMT and tumor angiogenesis in vitro and impaired tumor growth in mice. Molecular investigations indicated that MIR210HG directly targets HIF-1α protein and inhibits VHL-dependent HIF-1α protein degradation in ovarian cancer. Further results demonstrated that MIR210HG was upregulated in ovarian cancer tissues and correlated with tumor progression and poor prognosis of ovarian cancer patients. Our study suggests that hypoxia-induced MIR210HG promotes cancer progression by inhibiting HIF-1α degradation in ovarian cancer, which could be a therapeutic target for ovarian cancer.

Mechanisms of Hypercapnia-Induced Endoplasmic Reticulum Dysfunction

Protein transcription, translation, and folding occur continuously in every living cell and are essential for physiological functions. About one-third of all proteins of the cellular proteome interacts with the endoplasmic reticulum (ER). The ER is a large, dynamic cellular organelle that orchestrates synthesis, folding, and structural maturation of proteins, regulation of lipid metabolism and additionally functions as a calcium store. Recent evidence suggests that both acute and chronic hypercapnia (elevated levels of CO₂) impair ER function by different mechanisms, leading to adaptive and maladaptive regulation of protein folding and maturation. In order to cope with ER stress, cells activate unfolded protein response (UPR) pathways. Initially, during the adaptive phase of ER stress, the UPR mainly functions to restore ER protein-folding homeostasis by decreasing protein synthesis and translation and by activation of ER-associated degradation (ERAD) and autophagy. However, if the initial UPR attempts for alleviating ER stress fail, a maladaptive response is triggered. In this review, we discuss the distinct mechanisms by which elevated CO₂ levels affect these molecular pathways in the setting of acute and chronic pulmonary diseases associated with hypercapnia.

Sec62 promotes pro-angiogenesis of hepatocellular carcinoma cells under hypoxia

This study aimed to investigate the underlying molecular pathogenic mechanism of Sec62 in hepatocellular carcinoma (HCC). Microarray analysis was conducted to profile the global gene expression in the HCC cell line Huh7 cells transfected with Sec62high vs. NC and Sec62low vs. NC. Ingenuity pathway analysis and gene set enrichment analysis were used to perform Sec62-related signaling pathway analysis from screened differentially expressed genes (DEGs). A protein-protein interaction network was constructed. Experimental validation of the expression of key DEGs was conducted. Hypoxia-induced tube formation was undertaken to investigate the role of Sec62 in angiogenesis. A total of 74 intersected DEGs were identified from Huh7 cells with Sec62high vs. NC and Sec62low vs. NC. Among them, 65 DEGs were correlated with the expression of Sec62. The P53 signaling pathway was found to be enriched in Huh7 cells with Sec62high vs. NC, while the acute phase response signaling pathway was enriched in Huh7 cells with Sec62low vs. NC. DEGs, such as serine protease inhibitor E (SERPINE) and tumor necrosis factor receptor superfamily, member 11B (TNFRSF11B), were not only identified as the lead genes of these enriched pathways, but were also found to be closely related to Sec62. Moreover, knockdown of Sec62 decreased the expression of SERPINE1 (plasminogen activator inhibitor type 1 (PAI-1)) and TNFRSF11B, whereas overexpression of Sec62 had the opposite effects. In addition, knockdown of Sec62 inhibited hypoxia-induced tube formation via PAI-1. Sec62 promoted pro-angiogenesis of HCC under hypoxia by regulating PAI-1, and it may be a crucial angiogenic switch in HCC.

Understanding the Role of Autophagy in Cancer Formation and Progression Is a Real Opportunity to Treat and Cure Human Cancers

Simple Summary

The modulation of autophagy represents a potential therapeutic strategy for cancer. More than one hundred clinical trials have been conducted or are ongoing to explore the efficacy of autophagy modulators to reduce the tumor growth and potentiate the anti-cancer effects of conventional therapy. Despite this, the effective role of autophagy during tumor initiation, growth, and metastasis remains not well understood. Depending on the cancer type and stage of cancer, autophagy may have tumor suppressor properties as well as help cancer cells to proliferate and evade cancer therapy. The current review aims to summarize the current knowledge about the autophagy implications in cancer and report the therapeutic opportunities based on the modulation of the autophagy process.

Abstract

The malignant transformation of a cell produces the accumulation of several cellular adaptions. These changes determine variations in biological processes that are necessary for a cancerous cell to survive during stressful conditions. Autophagy is the main nutrient recycling and metabolic adaptor mechanism in eukaryotic cells, represents a continuous source of energy and biomolecules, and is fundamental to preserve the correct cellular homeostasis during unfavorable conditions. In recent decades, several findings demonstrate a close relationship between autophagy, malignant transformation, and cancer progression. The evidence suggests that autophagy in the cancer context has a bipolar role (it may act as a tumor suppressor and as a mechanism of cell survival for established tumors) and demonstrates that the targeting of autophagy may represent novel therapeutic opportunities. Accordingly, the modulation of autophagy has important clinical benefits in patients affected by diverse cancer types. Currently, about 30 clinical trials are actively investigating the efficacy of autophagy modulators to enhance the efficacy of cytotoxic chemotherapy treatments. A deeper understanding of the molecular pathways regulating autophagy in the cancer context will provide new ways to target autophagy for improving the therapeutic benefits. Herein, we describe how autophagy participates during malignant transformation and cancer progression, and we report the ultimate efforts to translate this knowledge into specific therapeutic approaches to treat and cure human cancers.

Crosstalk Between ER Stress, Autophagy and Inflammation

The endoplasmic reticulum (ER) is not only responsible for protein synthesis and folding but also plays a critical role in sensing cellular stress and maintaining cellular homeostasis. Upon sensing the accumulation of unfolded proteins due to perturbation in protein synthesis or folding, specific intracellular signaling pathways are activated, which are collectively termed as unfolded protein response (UPR). UPR expands the capacity of the protein folding machinery, decreases protein synthesis and enhances ER-associated protein degradation (ERAD) which degrades misfolded proteins through the proteasomes. More recent evidences suggest that UPR also amplifies cytokines-mediated inflammatory responses leading to pathogenesis of inflammatory diseases. UPR signaling also activates autophagy; a lysosome-dependent degradative pathwaythat has an extended capacity to degrade misfolded proteins and damaged ER. Thus, activation of autophagy limits inflammatory response and provides cyto-protection by attenuating ER-stress. Here we review the mechanisms that couple UPR, autophagy and cytokine-induced inflammation that can facilitate the development of novel therapeutic strategies to mitigate cellular stress and inflammation associated with various pathologies.

Mast cells: Therapeutic targets for COVID-19 and beyond

Mast cells (MCs) are innate immune cells that widely distribute throughout all tissues and express a variety of cell surface receptors. Upon activation, MCs can rapidly release a diverse array of preformed mediators residing within their secretory granules and newly synthesize a broad spectrum of inflammatory and immunomodulatory mediators. These unique features of MCs enable them to act as sentinels in response to rapid changes within their microenvironment. There is increasing evidence now that MCs play prominent roles in other pathophysiological processes besides allergic inflammation. In this review, we highlight the recent findings on the emerging roles of MCs in the pathogenesis of coronavirus disease-2019 (COVID-19) and discuss the potential of MCs as novel therapeutic targets for COVID-19 and other non-allergic inflammatory diseases.

Gambogenic Acid Induces Endoplasmic Reticulum Stress in Colorectal Cancer via the Aurora A Pathway

Colorectal cancer (CRC) is one of the most common malignancies in the world and has a poor prognosis. In the present research, gambogenic acid (GNA), isolated from the traditional Chinese medicine gamboge, markedly induced apoptosis and inhibited the proliferation of CRC in vitro and in vivo. Furthermore, GNA triggered endoplasmic reticulum (ER) stress, which subsequently activated inositol-requiring enzyme (IRE) 1α and the eukaryotic translation initiation factor (eIF) 2α pathway. Pretreatment with salubrinal (an eIF2α inhibitor) rescued GNA-induced cell death. Furthermore, GNA downregulated the expression of Aurora A. The Aurora A inhibitor alisertib decreased ER stress. In human colorectal adenocarcinoma tissue, Aurora A was upregulated compared to normal colorectal epithelial nuclei. Furthermore, GNA ameliorated mouse colitis-associated cancer models. Our findings demonstrated that GNA significantly inhibited the proliferation of CRC through activation of ER stress by regulating Aurora A, which indicates the potential of GNA for preventing the progression of CRC.