Critical role of TRPC6 in maintaining the stability of HIF-1α in glioma cells under hypoxia

Sevoflurane preconditioning promotes mesenchymal stem cells to relieve myocardial ischemia/reperfusion injury via TRPC6-induced angiogenesis

Background

Ischemic heart diseases is one of the leading causes of death worldwide. Although revascularization timely is an effective therapeutic intervention to salvage the ischemic myocardium, reperfusion itself causes additional myocardial injury called ischemia/reperfusion (I/R) injury. Bone marrow-derived mesenchymal stem cells (MSCs) is one of the promising cells to alleviate ischemic myocardial injury. However, this cell therapy is limited by poor MSCs survival after transplantation. Here, we investigated whether sevoflurane preconditioning could promote MSCs to attenuate myocardial I/R injury via transient receptor potential canonical channel 6 (TRPC6)-induced angiogenesis.

Methods

The anti-apoptotic effect of sevoflurane preconditioning on MSCs was determined by Annexin V-FITC/propidium iodide staining. TRPC6, hypoxia-inducible factor-1α (HIF-1α), Chemokine receptor 4 (CXCR4) and vascular endothelial growth factor (VEGF) protein expressions and VEGF release from MSCs were determined after hypoxia and reoxygenation (H/R). Small interfering RNA (siRNA) was used to knock down TRPC6 gene expression in MSCs. The angiogenesis of human umbilical vein endothelial cells (HUVECs) co-cultured with MSCs was determined by Matrigel tube formation. Myocardial I/R mouse model was induced by occluding left anterior descending coronary artery for 30 min and then reperfusion. MSCs or sevoflurane preconditioned MSCs were injected around the ligature border zone 5 min before reperfusion. Left ventricle systolic function, infarction size, serum LDH, cTnI and inflammatory cytokines were determined after reperfusion.

Results

Sevoflurane preconditioning up-regulated TRPC6, HIF-1α, CXCR4 and VEGF expressions in MSCs and VEGF release from MSCs under H/R, which were reversed by knockdown of TRPC6 gene using siRNA in MSCs. Furthermore, sevoflurane preconditioning promoted the angiogenic and anti-inflammatory effect of HUVECs co-cultured with MSCs. Sevoflurane preconditioned MSCs improved left ventricle systolic function and alleviated myocardial infarction and inflammation in mice subjected to I/R insult.

Conclusion

The current findings reveal that sevoflurane preconditioned MSCs boost angiogenesis in HUVECs subjected to H/R insult and attenuate myocardial I/R injury, which may be mediated by TRPC6 up-regulated HIF-1α, CXCR4 and VEGF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02649-3.

Local adaptations of Mediterranean sheep and goats through an integrative approach

Small ruminants are suited to a wide variety of habitats and thus represent promising study models for identifying genes underlying adaptations. Here, we considered local Mediterranean breeds of goats (n = 17) and sheep (n = 25) from Italy, France and Spain. Based on historical archives, we selected the breeds potentially most linked to a territory and defined their original cradle (i.e., the geographical area in which the breed has emerged), including transhumant pastoral areas. We then used the programs PCAdapt and LFMM to identify signatures of artificial and environmental selection. Considering cradles instead of current GPS coordinates resulted in a greater number of signatures identified by the LFMM analysis. The results, combined with a systematic literature review, revealed a set of genes with potentially key adaptive roles in relation to the gradient of aridity and altitude. Some of these genes have been previously implicated in lipid metabolism (SUCLG2, BMP2), hypoxia stress/lung function (BMPR2), seasonal patterns (SOX2, DPH6) or neuronal function (TRPC4, TRPC6). Selection signatures involving the PCDH9 and KLH1 genes, as well as NBEA/NBEAL1, were identified in both species and thus could play an important adaptive role.

Transient Receptor Potential (TRP) Ion Channels Involved in Malignant Glioma Cell Death and Therapeutic Perspectives

Among the most biologically, thus clinically, aggressive primary brain tumors are found malignant gliomas. Despite recent advances in adjuvant therapies, which include targeted and immunotherapies, after surgery and radio/chemotherapy, the tumor is recurrent and always lethal. Malignant gliomas also contain a pool of initiating stem cells that are highly invasive and resistant to conventional treatment. Ion channels and transporters are markedly involved in cancer cell biology, including glioma cell biology. Transient receptor potential (TRP) ion channels are calcium-permeable channels implicated in Ca²⁺ changes in multiple cellular compartments by modulating the driving force for Ca²⁺ entry. Recent scientific reports have shown that these channels contribute to the increase in glioblastoma aggressiveness, with glioblastoma representing the ultimate level of glioma malignancy. The current review focuses on each type of TRP ion channel potentially involved in malignant glioma cell death, with the ultimate goal of identifying new therapeutic targets to clinically combat malignant gliomas. It thus appears that cannabidiol targeting the TRPV2 type could be such a potential target.

Calcium signaling in cancer progression and therapy

The old Greek aphorism 'Panta Rhei' ('everything flows') is true for all living things in general. As a dynamic process, calcium signaling plays fundamental roles in cellular activities under both normal and pathological conditions, with recent researches uncovering its involvement in cell proliferation, migration, survival, gene expression, and more. The major question we address here is how calcium signaling affects cancer progression and whether it could be targeted to combine with classic chemotherapeutics or emerging immunotherapies to improve their efficacy.

The Role of TRPC6 in Renal Ischemia/Reperfusion and Cellular Hypoxia/Reoxygenation Injuries

Renal ischemia/reperfusion (I/R), a major cause of acute kidney injury (AKI), is a serious clinical event in patients during post-renal transplantation. I/R is associated with renal dysfunction and tubular apoptosis, and calcium (Ca²⁺) overload has been reported to be a crucial factor on tubular apoptosis in I/R injury (IRI). The canonical transient receptor potential channel 6 (TRPC6), a type of non-selective Ca²⁺ channel, is involved in many renal diseases. Our earlier study identified that TRPC6-mediated Ca²⁺ influx plays a novel role in suppressing cytoprotective autophagy triggered by oxidative stress in primary tubular epithelial cells (TECs). This study explored the potential beneficial impact of TRPC6 knockout (TRPC6^−/−) and the relevant cellular mechanisms against I/R-induced AKI in mice. Measuring changes of renal function, apoptotic index, and autophagy in mouse kidneys that suffered 24 h reperfusion after 40 min ischemia and working in vitro with TECs that suffered 24 h reoxygenation after 24 h hypoxia, we found that 1) IRI tissues had increased TRPC6 expression and TRPC6 knockout significantly ameliorated renal damage induced by IRI; 2) TRPC6 knockout enhanced the level of autophagy and alleviated the depolarization of mitochondrial membrane potential (ψm, MMP) and apoptotic changes upon IRI; and 3) IRI tissues had increased p-AKT and p-ERK1/2 expressions, while TRPC6 knockout could markedly reduce the phosphorylation of AKT and ERK1/2. These discoveries suggest that, by reducing Ca²⁺ overload, the underlying protective mechanism of TRPC6^−/− may be involved in down-regulation of PI3K/AKT and ERK signaling, which is likely to provide a new avenue for future AKI therapies.

Mechanisms of Invasion in Glioblastoma: Extracellular Matrix, Ca2+ Signaling, and Glutamate

Glioblastoma (GBM) is the most common and malignant form of primary brain tumor with a median survival time of 14–16 months in GBM patients. Surgical treatment with chemotherapy and radiotherapy may help increase survival by removing GBM from the brain. However, complete surgical resection to eliminate GBM is almost impossible due to its high invasiveness. When GBM cells migrate to the brain, they interact with various cells, including astrocytes, neurons, endothelial cells, and the extracellular matrix (ECM). They can also make their cell body shrink to infiltrate into narrow spaces in the brain; thereby, they can invade regions of the brain and escape from surgery. Brain tumor cells create an appropriate microenvironment for migration and invasion by modifying and degrading the ECM. During those processes, the Ca²⁺ signaling pathway and other signaling cascades mediated by various ion channels contribute mainly to gene expression, motility, and invasion of GBM cells. Furthermore, GBM cells release glutamate, affecting migration via activation of ionotropic glutamate receptors in an autocrine manner. This review focuses on the cellular mechanisms of glioblastoma invasion and motility related to ECM, Ca²⁺ signaling, and glutamate. Finally, we discuss possible therapeutic interventions to inhibit invasion by GBM cells.

A molecular signature associated with prolonged survival in glioblastoma patients treated with regorafenib

BACKGROUND

Patients with glioblastoma (GBM) have a dramatically poor prognosis. The recent REGOMA trial suggested an overall survival (OS) benefit of regorafenib in recurrent GBM patients. Considering the extreme genetic heterogeneity of GBMs, we aimed to identify molecular biomarkers predictive of differential response to the drug.

METHODS

Total RNA was extracted from tumor samples of patients enrolled in the REGOMA trial. Genome-wide transcriptome and micro (mi)RNA profiles were associated with patients' OS and progression-free survival.

RESULTS

In the first step, a set of 11 gene transcripts (HIF1A, CTSK, SLC2A1, KLHL12, CDKN1A, CA12, WDR1, CD53, CBR4, NIFK-AS1, RAB30-DT) and 10 miRNAs (miR-93-5p, miR-203a-3p, miR-17-5p, let-7c-3p, miR-101-3p, miR-3607-3p, miR-6516-3p, miR-301a-3p, miR-23b-3p, miR-222-3p) was filtered by comparing survival between regorafenib and lomustine arms. In the second step, a mini-signature of 2 gene transcripts (HIF1A, CDKN1A) and 3 miRNAs (miR-3607-3p, miR-301a-3p, miR-93-5p) identified a subgroup of patients showing prolonged survival after regorafenib administration (median OS range, 10.6-20.8 mo).

CONCLUSIONS

The study provides evidence that a signature based on the expression of 5 biomarkers could help identify a subgroup of GBM patients exhibiting a striking survival advantage when treated with regorafenib. Although the presented results must be confirmed in larger replication cohorts, the study highlights potential biomarker options to help guide the clinical decision among regorafenib and other treatments in patients with relapsing GBM.

Channeling Force in the Brain: Mechanosensitive Ion Channels Choreograph Mechanics and Malignancies

Force is everywhere. Through cell-intrinsic activities and interactions with the microenvironment, cells generate, transmit, and sense mechanical forces, such as compression, tension, and shear stress. These forces shape the mechanical properties of cells and tissues. Akin to how balanced biochemical signaling safeguards physiological processes, a mechanical optimum is required for homeostasis. The brain constructs a mechanical optimum from its cellular and extracellular constituents. However, in brain cancer, the mechanical properties are disrupted: tumor and nontumoral cells experience dysregulated solid and fluid stress, while tumor tissue develops altered stiffness. Mechanosensitive (MS) ion channels perceive mechanical cues to govern ion flux and cellular signaling. In this review, we describe the mechanical properties of the brain in healthy and cancer states and illustrate MS ion channels as sensors of mechanical cues to regulate malignant growth. Targeting MS ion channels offers disease insights at the interface of cancer, neuroscience, and mechanobiology to reveal therapeutic opportunities in brain tumors.

TRP Channels Regulation of Rho GTPases in Brain Context and Diseases

Neurological and neuropsychiatric disorders are mediated by several pathophysiological mechanisms, including developmental and degenerative abnormalities caused primarily by disturbances in cell migration, structural plasticity of the synapse, and blood-vessel barrier function. In this context, critical pathways involved in the pathogenesis of these diseases are related to structural, scaffolding, and enzymatic activity-bearing proteins, which participate in Ca²⁺- and Ras Homologs (Rho) GTPases-mediated signaling. Rho GTPases are GDP/GTP binding proteins that regulate the cytoskeletal structure, cellular protrusion, and migration. These proteins cycle between GTP-bound (active) and GDP-bound (inactive) states due to their intrinsic GTPase activity and their dynamic regulation by GEFs, GAPs, and GDIs. One of the most important upstream inputs that modulate Rho GTPases activity is Ca²⁺ signaling, positioning ion channels as pivotal molecular entities for Rho GTPases regulation. Multiple non-selective cationic channels belonging to the Transient Receptor Potential (TRP) family participate in cytoskeletal-dependent processes through Ca²⁺-mediated modulation of Rho GTPases. Moreover, these ion channels have a role in several neuropathological events such as neuronal cell death, brain tumor progression and strokes. Although Rho GTPases-dependent pathways have been extensively studied, how they converge with TRP channels in the development or progression of neuropathologies is poorly understood. Herein, we review recent evidence and insights that link TRP channels activity to downstream Rho GTPase signaling or modulation. Moreover, using the TRIP database, we establish associations between possible mediators of Rho GTPase signaling with TRP ion channels. As such, we propose mechanisms that might explain the TRP-dependent modulation of Rho GTPases as possible pathways participating in the emergence or maintenance of neuropathological conditions.

Ion Channels and Their Role in the Pathophysiology of Gliomas

Malignant gliomas are the most common primary central nervous system tumors and their prognosis is very poor. In recent years, ion channels have been demonstrated to play important roles in tumor pathophysiology such as regulation of gene expression, cell migration, and cell proliferation. In this review, we summarize the current knowledge on the role of ion channels on the development and progression of gliomas. Cell volume changes through the regulation of ion flux, accompanied by water flux, are essential for migration and invasion. Signaling pathways affected by ion channel activity play roles in cell survival and cell proliferation. Moreover, ion channels are involved in glioma-related seizures, sensitivity to chemotherapy, and tumor metabolism. Ion channels are potential targets for the treatment of these lethal tumors. Despite our increased understanding of the contributions of ion channels to glioma biology, this field remains poorly studied. This review summarizes the current literature on this important topic.

Roles for Ca2+ and K+ channels in cancer cells exposed to the hypoxic tumour microenvironment

For twenty years, ion channels have been studied in cancer progression. Several information have been collected about their involvement in cancer cellular processes like cell proliferation, motility and their participation in tumour progression using in-vivo models. Tumour microenvironment is currently the focus of many researches and the highlighting of the relationship between cancer cells and surrounding elements, is expanding. One of the major physic-chemical parameter involved in tumour progression is the hypoxia conditions observed in solid cancer. Due to their position on the cell membrane, ion channels are good candidates to transduce or to be modulated by environmental modifications. Until now, few reports have been interested in the modification of ion channel activities or expression in this context, compared to other pathological situations such as ischemia reperfusion. The aim of our review is to summarize the current knowledge about the calcium and potassium channels properties in the context of hypoxia in tumours. This review could pave the way to orientate new studies around this exciting field to obtain new potential therapeutic approaches.

Over-Expression of TRPC6 via CRISPR Based Synergistic Activation Mediator in BMSCs Ameliorates Brain Injury in a Rat Model of Cerebral Ischemia/Reperfusion

Stroke is a major life-threatening and disabling disease with a restricted therapeutic approach. Bone marrow stromal cells (BMSCs) possess proliferative ability and a multi-directional differentiation potential, and secrete a range of trophic/growth factors that can protect neurons after cerebral ischemia/reperfusion. Transient receptor potential canonical (TRPC) is a family of non-selective channels permeable to Ca2+, with several functions including neuronal survival. Over-expression of TRPC6, a subtype of the TRPC family, was shown to protect neurons against cerebral ischemia/reperfusion injury. However, it remains unclear whether over-expression of TRPC6 in BMSCs can further reduce brain injury after ischemia/reperfusion. In the present study, we report that over-expression of TRPC6 via a CRISPR-based synergistic activation mediator in BMSCs provided a greater reduction of brain injury in a rat model of ischemia/reperfusion. Further, the improved neurofunctional outcomes were associated with increased TRPC6 and brain derived neurotrophic factor expression levels. Overall, these data suggest that TRPC6 over-expressing BMSCs may be a promising therapeutic agent for ischemic stroke.

Necrostatin-1 Attenuates Renal Ischemia and Reperfusion Injury via Meditation of HIF-1α/mir-26a/TRPC6/PARP1 Signaling

Necroptosis, oxidative stress, and inflammation are major contributors to the pathogenesis of ischemic acute kidney injury. Necrostatin-1 (Nec-1), an inhibitor of the kinase domain of receptor-interacting protein kinase-1 (RIP1), has been reported to regulate renal ischemia and reperfusion (I/R) injury; however, its underlying mechanism of action remains unclear. HK-2 cells were used to create an in vitro I/R model, in which the cells were subjected to hypoxia, followed by 2, 6, and 12 h of reoxygenation. For the in vivo study, a rat model of renal I/R was established in which samples of rat blood serum and kidney tissue were harvested after reperfusion to assess renal function and detect histological changes. Cell viability and necroptosis were analyzed using the Cell Counting Kit (CCK)-8 assay and flow cytometry, respectively. The expression levels of molecules associated with necroptosis, oxidative stress, and inflammation were determined by real-time PCR, western blotting, immunofluorescence staining, and ELISA. Luciferase and chromatin immunoprecipitation (ChIP) assays were performed to confirm the relevant downstream signaling pathway. We found that pretreatment with Nec-1 significantly decreased hypoxia-inducible factor-1α (HIF-1α) and miR-26a expression, as well as the levels of factors associated with necroptosis (RIP1, RIP3, and Sirtuin-2), oxidative stress (malondialdehyde [MDA], NADP⁺/NADPH ratio), and inflammation (interleukin [IL]-1β, IL-10, and tumor necrosis factor alpha [TNF-α]) in I/R injury cells and the rat model. However, these effects could be reversed by miR-26a overexpression or TRPC6 knockdown. Mechanistic studies demonstrated that HIF-1α directly binds to the promoter region of miR-26a, and that TRPC6 is a potential target gene for miR-26a. Our findings indicate that Nec-1 can effectively protect against renal I/R injury by inhibiting necroptosis, oxidative stress, and inflammation, and may exert its effects through mediation of the HIF-1α/miR-26a/TRPC6/PARP1 signaling pathway.

Resensitization of cisplatin resistance ovarian cancer cells to cisplatin through pretreatment with low-dose fraction radiation

Objective

Cisplatin is the first‐line chemotherapy for ovarian cancer. However, cisplatin resistance is severely affecting the treatment efficacy. FOXO3a has been reported to be involved in reversing chemotherapy resistance. However, whether low‐dose fraction radiation therapy (LDFRT) can reverse cisplatin resistance remains unclear. This study aimed to explore the effect of LDFRT on cisplatin resistance and its relation with FOXO3a expression in vitro.

Methods

The toxicity of cisplatin on SKOV3/DDP cells was evaluated by CCK8 assay and cell apoptosis was measured by Annexin V‐FITC staining as well as Hoechst33342 staining. The expression of FOXO3a and other relative proteins was measured by western blot.

Results

Our study found that LDFRT enhanced cisplatin‐induced apoptosis of SKOV3/DDP cells and promoted the expression of FOXO3a and pro‐apoptotic protein PUMA. In addition, overexpression of FOXO3a promoted PUMA activity and toxicity of cisplatin on SKOV3/DDP cells.

Conclusion

LDFRT reverses cisplatin resistance of SKOV3/DDP cells possibly by upregulating the expression of FOXO3a and its downstream target PUMA, suggesting that LDFRT might be a potent chemosensitizer for the treatment of ovarian cancer.

Role of HIF1α Regulatory Factors in Stem Cells

Hypoxia-inducible factor 1 (HIF1) is a master transcription factor that induces the transcription of genes involved in the metabolism and behavior of stem cells. HIF1-mediated adaptation to hypoxia is required to maintain the pluripotency and survival of stem cells under hypoxic conditions. HIF1 activity is well known to be tightly controlled by the alpha subunit of HIF1 (HIF1α). Understanding the regulatory mechanisms that control HIF1 activity in stem cells will provide novel insights into stem cell biology under hypoxia. Recent research has unraveled the mechanistic details of HIF1α regulating processes, suggesting new strategies for regulating stem cells. This review summarizes recent experimental studies on the role of several regulatory factors (including calcium, 2-oxoglutarate-dependent dioxygenase, microtubule network, importin, and coactivators) in regulating HIF1α activity in stem cells.

Calcium Signaling in Brain Cancers: Roles and Therapeutic Targeting

Calcium signaling, in addition to its numerous physiological roles, is also implicated in several pathological conditions including cancer. An increasing body of evidence suggest critical roles of calcium signaling in the promotion of different aspects of cancer, including cell proliferation, therapy resistance and metastatic-related processes. In many cases, this is associated with altered expression and/or activity of some calcium channels and pumps. Brain cancers have also been the subject of many of these studies. In addition to diverse roles of calcium signals in normal brain function, a number of proteins involved in calcium transport are implicated to have specific roles in some brain cancers including gliomas, medulloblastoma, neuroblastoma and meningioma. This review discusses research that has been conducted so far to understand diverse roles of Ca²⁺-transporting proteins in the progression of brain cancers, as well as any attempts to target these proteins towards a therapeutic approach for the control of brain cancers. Finally, some knowledge gaps in the field that may need to be further considered are also discussed.

Zhenbao Pill reduces Treg cell proportion in acute spinal cord injury rats by regulating TUG1/miR-214/HSP27 axis

Background: Acute spinal cord injury (SCI) is one of the weakest pathologies that seriously affect the quality of life of patients. Objective: To study the mechanism of how Zhenbao Pill reduces Treg cell proportion and improves acute SCI. Methods: A rat SCI model was established. Flow cytometry analysis was performed to determine the Treg cell proportion. RNA immunoprecipitation (RIP) and RNA pull-down were applied in confirming taurine up-regulated gene 1 (TUG1) and miR-214 binding. Intrathecal injection of TUG1 siRNA was also conducted to determine the effect of TUG1 in vivoResults: Zhenbao Pill promoted the expression of TUG1 and heat shock protein 27 (HSP27) protein, and reduced the expression of miR-214 and forkhead box protein p3 (Foxp3) as well as Treg cell proportion in a concentration-dependent manner in SCI rats or in vitro cultured CD4+ T cells. Knockdown of TUG1 reversed the high protein expression of HSP27 and the inhibition of Treg cell proportion as well as Foxp3 protein induced by Zhenbao Pill, and miR-214 inhibitor canceled the TUG1 knockdown effect. Further, miR-214 mimic reversed the inhibition of Treg cell proportion and Foxp3 protein expression by Zhenbao Pill, which was abolished by the overexpression of HSP27. The mechanism was validated in animal experiments. Conclusion: Zhenbao Pill regulated TUG1/miR-214/HSP27 signaling pathway to reduce Treg cell proportion and thus relieve acute SCI.

GAS5 promotes airway smooth muscle cell proliferation in asthma via controlling miR-10a/BDNF signaling pathway

AIMS

To explore the role of long non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) in the cell proliferation of airway smooth muscle cells (ASMCs) in asthma.

MATERIALS AND METHODS

An asthma rat model was established by ovalbumin sensitization and challenge. The expression of GAS5, miR-10a and BDNF mRNA and protein was determined with qRT-PCR and western blot, separately. The targeting relationship between GAS5 and miR-10a was examined with RNA immunoprecipitation and RNA pull-down assay; the interaction between miR-10a and BDNF was evaluated by luciferase reporter assay. Cell Proliferation Assay (MTS) was used for ASMC proliferation detection. Knock-down of GAS5 was performed in asthmatic rats to determine the effects of GAS5 in vivo.

KEY FINDINGS

Compared with control group, the inspiratory resistance and expiratory resistance were increased in asthma group; and the expression of GAS5, miR-10a and BDNF was higher, lower and higher, respectively. The expression of GAS5 and miR-10a was elevated and repressed, respectively, by platelet-derived growth factor-BB (PDGF-BB). GAS5 functioned as a bait of miR-10a. GAS5 regulates BDNF expression through miR-10a. PDGF-BB promotes the cell proliferation of ASMCs through miR-10a/BDNF. Knock-down of GAS5 significantly decreased airway hyperresponsiveness in asthmatic rats.

SIGNIFICANCE

The lncRNA GAS5/miR-10a/BDNF regulatory axis played an important role in promoting ASMCs proliferation, thus contributing to asthma.

The Role of TRP Channels in the Metastatic Cascade

A dysregulated cellular Ca2+ homeostasis is involved in multiple pathologies including cancer. Changes in Ca2+ signaling caused by altered fluxes through ion channels and transporters (the transportome) are involved in all steps of the metastatic cascade. Cancer cells thereby "re-program" and "misuse" the cellular transportome to regulate proliferation, apoptosis, metabolism, growth factor signaling, migration and invasion. Cancer cells use their transportome to cope with diverse environmental challenges during the metastatic cascade, like hypoxic, acidic and mechanical cues. Hence, ion channels and transporters are key modulators of cancer progression. This review focuses on the role of transient receptor potential (TRP) channels in the metastatic cascade. After briefly introducing the role of the transportome in cancer, we discuss TRP channel functions in cancer cell migration. We highlight the role of TRP channels in sensing and transmitting cues from the tumor microenvironment and discuss their role in cancer cell invasion. We identify open questions concerning the role of TRP channels in circulating tumor cells and in the processes of intra- and extravasation of tumor cells. We emphasize the importance of TRP channels in different steps of cancer metastasis and propose cancer-specific TRP channel blockade as a therapeutic option in cancer treatment.

miR-411 suppresses acute spinal cord injury via downregulation of Fas ligand in rats

OBJECTIVE

To explore the role of miR-411/FasL in acute spinal cord injury (ASCI).

METHODS

The ASCI rat model was established, and expression of miR-411 and Fas ligand (FasL) was examined. Basso, Beattie and Bresnahan (BBB) score was used to evaluate the rats' neurological function. PC12 oxygen-glucose deprivation (OGD) model was also established. Gene manipulation (including miR-411 mimic or inhibitor) was used to modulate gene expression. Luciferase reporter assay was conducted to confirm the targeting relationship between miR-411 and FasL. Flow cytometry was applied in the measurement of PC12 cell apoptosis. Finally, the miR-411 mimic was injected into the vertebral canal of ASCI rats to determine the effects of miR-411 in vivo.

RESULTS

Compared with sham group, the expression of miR-411 and FasL was significantly decreased and increased in ASCI group, respectively (P < 0.05). Similarly, the expression of miR-411 and FasL was significantly lower and higher in OGD group than that in control group, respectively (P < 0.05). miR-411 directly controlled the FasL expression. miR-411 mimic can dramatically reduce the increased percentage of apoptosis cells caused by OGD when comparing to mimic control, which was greatly reversed by the overexpression of FasL (P < 0.05). Further, the BBB score was significantly elevated in the miR-411 mimic group when comparing to mimic control group, with decreased FasL expression (P < 0.05).

CONCLUSION

miR-411 mimic suppressed PC12 cell apoptosis via FasL, and relieved ASCI in rats.

IGF-1R Promotes Symmetric Self-Renewal and Migration of Alkaline Phosphatase+ Germ Stem Cells through HIF-2α-OCT4/CXCR4 Loop under Hypoxia

Hypoxia cooperates with endocrine signaling to maintain the symmetric self-renewal proliferation and migration of embryonic germline stem cells (GSCs). However, the lack of an appropriate in vitro cell model has dramatically hindered the understanding of the mechanism underlying this cooperation. Here, using a serum-free system, we demonstrated that hypoxia significantly induced the GSC mesenchymal transition, increased the expression levels of the pluripotent transcription factor OCT4 and migration-associated proteins (SDF-1, CXCR4, IGF-1, and IGF-1R), and activated the cellular expression and translocalization of the CXCR4-downstream proteins ARP3/pFAK. The underlying mechanism involved significant IGF-1/IGF-1R activation of OCT4/CXCR4 expression through HIF-2α regulation. Picropodophyllin-induced inhibition of IGF-1R phosphorylation significantly suppressed hypoxia-induced SDF-1/CXCR4 expression and cell migration. Furthermore, transactivation between IGF-1R and CXCR4 was involved. In summary, we demonstrated that niche hypoxia synergistically cooperates with its associated IGF-1R signaling to regulate the symmetric division (self-renewal proliferation) and cell migration of alkaline phosphatase-positive GSCs through HIF-2α-OCT4/CXCR4 during embryogenesis.

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Hypoxia regulated AP⁺GSC self-renewal and cell migration via IGF-1R and CXCR4

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Hypoxia increased IGF1/IGF-1R and SDF-1/CXCR4 to promote AP⁺GSC migration

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Crosstalk of IGF-1/IGF-1R and SDF-1/CXCR4 signaling in AP⁺GSCs under hypoxia

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Inhibition of IGF-1R phosphorylation suppressed hypoxia-induced cell migration

Hypoxia increases glucose transporter 1 expression in bovine corpus luteum at the early luteal stage

A major role of the corpus luteum (CL) is to produce progesterone (P4). The CL has immature vasculature shortly after ovulation, suggesting it exists under hypoxic conditions. Hypoxia-inducible factor-1 (HIF1) induces the expression of glucose transporter 1 (GLUT1). To clarify the physiological roles of GLUT1 in bovine CL, we examined GLUT1 mRNA expression in the CL under hypoxic conditions by quantitative RT-PCR. We also measured the effects of glucose (0-25 mM) and GLUT1 inhibitors (cytochalasin B, STF-31) on P4 production in bovine luteal cells. GLUT1 mRNA expression in bovine CL was higher at the early luteal stage compared to the other later stages. Hypoxia (3% O₂) increased GLUT1 mRNA expression in early luteal cells, but not in mid luteal cells. Glucose (0-25 mM) increased P4 production in early luteal cells, but not in mid luteal cells. Both GLUT1 inhibitors decreased P4 production in early and mid luteal cells. Overall, the results suggest that GLUT1 (possibly induced by hypoxic conditions in the early CL) plays a role in the establishment and development of bovine CL, especially in supporting luteal P4 synthesis at the early luteal stage.

TRPC6 channels modulate the response of pancreatic stellate cells to hypoxia

Pancreatic cancer is characterized by a massive fibrosis (desmoplasia), which is primarily caused by activated pancreatic stellate cells (PSCs). This leads to a hypoxic tumor microenvironment further reinforcing the activation of PSCs by stimulating their secretion of growth factors and chemokines. Since many of them elicit their effects via G-protein-coupled receptors (GPCRs), we tested whether TRPC6 channels, effector proteins of many G-protein-coupled receptor pathways, are required for the hypoxic activation of PSCs. Thus far, the function of ion channels in PSCs is virtually unexplored. qPCR revealed TRPC6 channels to be one of the most abundant TRPC channels in primary cultures of murine PSCs. TRPC6 channel function was assessed by comparing PSCs from TRPC6^-/- mice and wildtype (wt) littermates. Cell migration, Ca²⁺ signaling, and cytokine secretion were analyzed as readout for PSC activation. Hypoxia was induced by incubating PSCs for 24 h in 1% O₂ or chemically with dimethyloxalylglycine (DMOG). PSCs migrate faster in response to hypoxia. Due to reduced autocrine stimulation, TRPC6^-/- PSCs fail to increase their rate of migration to the same level as wt PSCs under hypoxic conditions. This defect could not be overcome by the stimulation with platelet-derived growth factor. In line with these results, calcium influx is increased in wt but not TRPC6^-/- PSCs under hypoxia. We conclude that TRPC6 channels of PSCs are major effector proteins in an autocrine stimulation pathway triggered by hypoxia.

The calcium-cancer signalling nexus

The calcium signal is a powerful and multifaceted tool by which cells can achieve specific outcomes. Cellular machinery important in tumour progression is often driven or influenced by changes in calcium ions; in some cases this regulation occurs within spatially defined regions. Over the past decade there has been a deeper understanding of how calcium signalling is remodelled in some cancers and the consequences of calcium signalling on key events such as proliferation, invasion and sensitivity to cell death. Specific calcium signalling pathways have also now been identified as playing important roles in the establishment and maintenance of multidrug resistance and the tumour microenvironment.

TRPC Channels and Glioma

Glioma is the most common type of brain tumors and malignant glioma is extremely lethal, with patients' 5-year survival rate less than 10%. Treatment of gliomas poses remarkable clinical challenges, not only because of their particular localization but also because glioma cells possess several malignant biological features, including highly proliferative, highly invasive, highly angiogenic, and highly metabolic aberrant. All these features make gliomas highly recurrent and drug resistant. Finding new and effective molecular drug targets for glioma is an urgent and critical task for both basic and clinical research. Recent studies have proposed a type of non-voltage-gated calcium channels, namely, canonical transient receptor potential (TRPC) channels, to be newly emerged potential drug targets for glioma. They are heavily involved in the proliferation, migration, invasion, angiogenesis, and metabolism of glioma cells. Abundant evidence from both cell models and preclinical mouse models has demonstrated that inhibition of TRPC channels shows promising anti-glioma effect. In this chapter, we will give a comprehensive review on the current progress in the studies on TRPC channels and glioma and discuss their potential clinical implication in glioma therapy.

TRPC Channel Downstream Signaling Cascades

The family of TRP channel is comprised of a large group of cation-permeable channels, displaying as signaling integrators for sensing extracellular stimulus and initiating intracellular signaling cascades. This chapter offers a brief review of the signaling molecules related to TRPC channels, the first identified mammalian TRP family. Besides the signaling molecules involved in TRPC activation, I will focus on their upstream and downstream signaling cascades and the molecules involved in their intracellular trafficking.

Advances in the targeting of HIF-1α and future therapeutic strategies for glioblastoma multiforme (Review)

Cell metabolism can be reprogrammed by tissue hypoxia leading to cell transformation and glioblastoma multiforme (GBM) progression. In response to hypoxia, GBM cells are able to express a transcription factor called hypoxia inducible factor-1 (HIF-1). HIF-1 belongs to a family of heterodimeric proteins that includes HIF-1α and HIF-1β subunits. HIF-1α has been reported to play a pivotal role in GBM development and progression. In the present review, we discuss the role of HIF-1α in glucose uptake, cancer proliferation, cell mobility and chemoresistance in GBM. Evidence from previous studies indicates that HIF-1α regulates angiogenesis, metabolic and transcriptional signaling pathways. Examples of such are the EGFR, PI3K/Akt and MAPK/ERK pathways. It affects cell migration and invasion by regulating glucose metabolism and growth in GBM cells. The present review focuses on the strategies through which to target HIF-1α and the related downstream genes highlighting their regulatory roles in angiogenesis, apoptosis, migration and glucose metabolism for the development of future GBM therapeutics. Combined treatment with inhibitors of HIF-1α and glycolysis may enhance antitumor effects in clinical settings.

Protective role of hypoxia-inducible factor-1α-dependent CD39 and CD73 in fulminant acute liver failure

Acute liver failure (ALF) is a severe life-threatening disease which usually arises in patients with-irreversible liver illnesses. Although human ectonucleotide triphosphate diphosphohydrolase-1, E-NTPDase1 (CD39) and ecto-5'-nucleotidase, Ecto5'NTase (CD73) are known to protect tissues from ALF, the expression and function of CD39 and CD73 during ALF are currently not fully investigated. We tested whether CD39 and CD73 are upregulated by hypoxia inducible factor (HIF)-1α, and improve ischemic tolerance to ALF. To test our hypothesis, liver biopsies were obtained and we found that CD39 and CD73 mRNA and proteins from human specimens were dramatically elevated in ALF. We investigated that induction of CD39 and CD73 in ALF-related with wild type mice. In contrast, deletion of cd39 and cd73 mice has severe ALF. In this study, we concluded that CD39 and CD73 are molecular targets for the development of drugs for ALF patients care.

Calcium Channels and Associated Receptors in Malignant Brain Tumor Therapy

Malignant brain tumors are highly lethal and aggressive. Despite recent advances in the current therapies, which include the combination of surgery and radio/chemotherapy, the average survival rate remains poor. Altered regulation of ion channels is part of the neoplastic transformation, which suggests that ion channels are involved in cancer. Distinct classes of calcium-permeable channels are abnormally expressed in cancer and are likely involved in the alterations underlying malignant growth. Specifically, cytosolic Ca(2+) activity plays an important role in the regulation of cell proliferation, and Ca(2+) signaling is altered in proliferating tumor cells. A series of previous studies emphasized the importance of the T-type low-voltage-gated calcium channels (VGCC) in different cancer types, including gliomas, and remarkably, pharmacologic inhibition of T-type VGCC caused antiproliferative effects and triggered apoptosis of human glioma cells. Other calcium permeable channels, such as transient receptor potential (TRP) channels, contribute to changes in Ca(2+) by modulating the driving force for Ca(2+) entry, and some TRP channels are required for proliferation and migration in gliomas. Furthermore, recent evidence shows that TRP channels contribute to the progression and survival of the glioblastoma patients. Likewise, the purinergic P2X7 receptor acts as a direct conduit for Ca(2+)-influx and an indirect activator of voltage-gated Ca(2+)-channel. Evidence also shows that P2X7 receptor activation is linked to elevated expression of inflammation promoting factors, tumor cell migration, an increase in intracellular mobilization of Ca(2+), and membrane depolarization in gliomas. Therefore, this review summarizes the recent findings on calcium channels and associated receptors as potential targets to treat malignant gliomas.

"TRP inflammation" relationship in cardiovascular system

Despite considerable advances in the research and treatment, the precise relationship between inflammation and cardiovascular (CV) disease remains incompletely understood. Therefore, understanding the immunoinflammatory processes underlying the initiation, progression, and exacerbation of many cardiovascular diseases is of prime importance. The innate immune system has an ancient origin and is well conserved across species. Its activation occurs in response to pathogens or tissue injury. Recent studies suggest that altered ionic balance, and production of noxious gaseous mediators link to immune and inflammatory responses with altered ion channel expression and function. Among plausible candidates for this are transient receptor potential (TRP) channels that function as polymodal sensors and scaffolding proteins involved in many physiological and pathological processes. In this review, we will first focus on the relevance of TRP channel to both exogenous and endogenous factors related to innate immune response and transcription factors related to sustained inflammatory status. The emerging role of inflammasome to regulate innate immunity and its possible connection to TRP channels will also be discussed. Secondly, we will discuss about the linkage of TRP channels to inflammatory CV diseases, from a viewpoint of inflammation in a general sense which is not restricted to the innate immunity. These knowledge may serve to provide new insights into the pathogenesis of various inflammatory CV diseases and their novel therapeutic strategies.