Employing the sustained-release properties of poly(lactic-co-glycolic acid) nanoparticles to reveal a novel mechanism of sodium-hydrogen exchanger 1 in neuropathic pain.

Neuropathic pain is caused by injury or disease of the somatosensory system, and its course is usually chronic. Several studies have been dedicated to investigating neuropathic pain-related targets; however, little attention has been paid to the persistent alterations that these targets, some of which may be crucial to the pathophysiology of neuropathic pain. The present study aimed to identify potential targets that may play a crucial role in neuropathic pain and validate their long-term impact. Through bioinformatics analysis of RNA sequencing results, we identified Slc9a1 and validated the reduced expression of sodium-hydrogen exchanger 1 (NHE1), the protein that Slc9a1 encodes, in the spinal nerve ligation (SNL) model. Colocalization analysis revealed that NHE1 is primarily co-localized with vesicular glutamate transporter 2-positive neurons. In vitro experiments confirmed that poly(lactic-co-glycolic acid) nanoparticles loaded with siRNA successfully inhibited NHE1 in SH-SY5Y cells, lowered intracellular pH, and increased intracellular calcium concentrations. In vivo experiments showed that sustained suppression of spinal NHE1 expression by siRNA-loaded nanoparticles resulted in delayed hyperalgesia in naïve and SNL model rats, whereas amiloride-induced transient suppression of NHE1 expression yielded no significant changes in pain sensitivity. We identified Slc9a1, which encodes NHE1, as a key gene in neuropathic pain. Utilizing the sustained release properties of nanoparticles enabled us to elucidate the chronic role of decreased NHE1 expression, establishing its significance in the mechanisms of neuropathic pain.

AXL is required for hypoxia-mediated hypoxia-inducible factor-1 alpha function in glioblastoma.

Glioblastoma (GBM) is the most aggressive type of central nervous system tumor. Molecular targeting may be important when developing efficient GBM treatment strategies. Sequencing of GBMs revealed that the receptor tyrosine kinase (RTK)/RAS/phosphatidylinositol-3-kinase pathway was altered in 88% of samples. Interestingly, AXL, a member of RTK, was proposed as a promising target in glioma therapy. However, the molecular mechanism of AXL modulation of GBM genesis and proliferation is still unclear. In this study, we investigated the expression and localization of hypoxia-inducible factor-1 alpha (HIF-1α) by AXL in GBM. Both AXL mRNA and protein are overexpressed in GBM. Short-interfering RNA knockdown of AXL in U251-MG cells reduced viability and migration. However, serum withdrawal reduced AXL expression, abolishing the effect on viability. AXL is also involved in hypoxia regulation. In hypoxic conditions, the reduction of AXL decreased the level and nuclear localization of HIF-1α. The co-expression of HIF-1α and AXL was found in human GBM samples but not normal tissue. This finding suggests a mechanism for GBM proliferation and indicates that targeting AXL may be a potential GBM therapeutic. Supplementary Information: The online version contains supplementary material available at 10.1007/s43188-023-00195-z.

MARS2 drives metabolic switch of non-small-cell lung cancer cells via interaction with MCU.

Mitochondrial methionyl-tRNA synthetase (MARS2) canonically mediates the formation of fMet-tRNAifMet for mitochondrial translation initiation. Mitochondrial calcium uniporter (MCU) is a major gate of Ca2+ flux from cytosol into the mitochondrial matrix. We found that MARS2 interacts with MCU and stimulates mitochondrial Ca2+ influx. Methionine binding to MARS2 would act as a molecular switch that regulates MARS2-MCU interaction. Endogenous knockdown of MARS2 attenuates mitochondrial Ca2+ influx and induces p53 upregulation through the Ca2+-dependent CaMKII/CREB signaling. Subsequently, metabolic rewiring from glycolysis into pentose phosphate pathway is triggered and cellular reactive oxygen species level decreases. This metabolic switch induces inhibition of epithelial-mesenchymal transition (EMT) via cellular redox regulation. Expression of MARS2 is regulated by ZEB1 transcription factor in response to Wnt signaling. Our results suggest the mechanisms of mitochondrial Ca2+ uptake and metabolic control of cancer that are exerted by the key factors of the mitochondrial translational machinery and Ca2+ homeostasis.

Targeting spinal microglia with fexofenadine-loaded nanoparticles prolongs pain relief in a rat model of neuropathic pain.

Targeting microglial activation is emerging as a clinically promising drug target for neuropathic pain treatment. Fexofenadine, a histamine receptor 1 antagonist, is a clinical drug for the management of allergic reactions as well as pain and inflammation. However, the effect of fexofenadine on microglial activation and pain behaviors remains elucidated. Here, we investigated nanomedicinal approach that targets more preferentially microglia and long-term analgesics. Fexofenadine significantly abolished histamine-induced microglial activation. The fexofenadine-encapsulated poly(lactic-co-glycolic acid) nanoparticles (Fexo NPs) injection reduced the pain sensitivity of spinal nerve ligation rats in a dose-dependent manner. This alleviation was sustained for 4 days, whereas the effective period by direct fexofenadine injection was 3 h. Moreover, Fexo NPs inhibited microglial activation, inflammatory signaling, cytokine release, and a macrophage phenotype shift towards the alternative activated state in the spinal cord. These results show that Fexo NPs exhibit drug repositioning promise as a long-term treatment modality for neuropathic pain.

Emerging role of LETM1/GRP78 axis in lung cancer.

The selective autophagy of damaged mitochondria is called mitophagy. Mitochondrial dysfunction, mitophagy, and apoptosis have been suggested to be interrelated in various human lung carcinomas. Leucine zipper EF-hand-containing transmembrane protein-1 (LETM1) was cloned in an attempt to identify candidate genes for Wolf-Hirschhorn syndrome. LETM1 plays a role in mitochondrial morphology, ion homeostasis, and cell viability. LETM1 has also been shown to be overexpressed in different human cancer tissues, including lung cancer. In the current study, we have provided clear evidence that LETM1 acts as an anchoring protein for the mitochondria-associated ER membrane (MAM). Fragmented mitochondria have been found in lung cancer cells with LETM1 overexpression. In addition, a reduction of mitochondrial membrane potential and significant accumulation of microtubule-associated protein 1 A/1B-light chain 3 punctate, which localizes with Red-Mito, was found in LETM1-overexpressed cells, suggesting that mitophagy is upregulated in these cells. Interestingly, glucose-regulated protein 78 kDa (GRP78; an ER chaperon protein) and glucose-regulated protein 75 kDa (GRP75) were posited to interact with LETM1 in the immunoprecipitated LETM1 of H460 cells. This interaction was enhanced in cells treated with carbonyl cyanide m-chlorophenylhydrazone, a chemical mitophagy inducer. Treatment of cells with honokiol (a GRP78 inhibitor) blocked LETM1-mediated mitophagy, and CRISPR/Cas9-mediated GRP75 knockout inhibited LETM1-induced autophagy. Thus, GRP78 interacts with LETM1. Taken together, these observations support the notion that the complex formation of LETM1/GRP75/GRP78 might be an important step in MAM formation and mitophagy, thus regulating mitochondrial quality control in lung cancer.

Scavenger receptor class F member 2 (SCARF2) as a novel therapeutic target in glioblastoma.

Scavenger receptor class F member 2 (SCARF2) is expressed by endothelial cells with very large cytoplasmic domains and is the second isotype, also known as scavenger receptor expressed by endothelial cells 2 (SREC-2). SREC-1 plays an important role in the binding and endocytosis of various endogenous and exogenous ligands. Many studies have been carried out on modified low-density lipoprotein internalization activity, but there have been few studies on SCARF2. Higher expression of SCARF2 has been found in glioblastoma (GBM) than normal brain tissue. Through analysis of The Cancer Genome Atlas database, it was confirmed that SCARF2 is widely expressed in GBM, and increased SCARF2 expression correlated with a poor prognosis in patients with glioma. The results of this study showed that the expression of SCARF2 is increased in GBM cell lines and patients, suggesting that SCARF2 may be a potential diagnostic marker and therapeutic molecule for cancers including glioma.

Application of PLGA nanoparticles to enhance the action of duloxetine on microglia in neuropathic pain.

Duloxetine (DLX) is a selective serotonin and noradrenaline reuptake inhibitor (SNRI) used for the treatment of pain, but it has been reported to show side effects in 10-20% of patients. Its analgesic efficacy in central pain is putatively related to its influence on descending inhibitory neuronal pathways. However, DLX can also affect the activation of microglia. This study was performed to investigate whether PLGA nanoparticles (NPs), which are expected to enhance targeting to microglia, can improve the analgesic efficacy and limit the side effects of DLX. PLGA NPs encapsulating a low dose of DLX (DLX NPs) were synthesized and characterized and their localization was determined. The analgesic and anti-inflammatory effects of DLX NPs were evaluated in a spinal nerve ligation (SNL)-induced neuropathic pain model. The analgesic effect of DLX lasted for only a few hours and disappeared within 1 day. However, DLX NPs alleviated mechanical allodynia, and the effect was maintained for 1 week. DLX NPs were localized to the spinal microglia and suppressed microglial activation, phosphorylation of p38/NF-κB-mediated pathways and the production of inflammatory cytokines in the spinal dorsal horn of SNL rats. We demonstrated that DLX NPs can provide a prolonged analgesic effect by enhanced targeting of microglia. Our observations imply that DLX delivery through nanoparticle encapsulation allows drug repositioning with a prolonged analgesic effect, and reduces the potential side effects of abuse and overdose.

Corrigendum: Current Knowledge on the Function of α-Methyl Acyl-CoA Racemase in Human Diseases.

[This corrects the article DOI: 10.3389/fmolb.2020.00153.].

Beneficial effects of Diplectria barbata (Wall. Ex C. B. Clarke) Franken et Roos extract on aging and antioxidants in vitro and in vivo.

The purpose of this study is to explore the effects of Diplectria barbata (Wall. Ex C.B. Clarke) Franken & Roons (DFR) on wound healing, antioxidant and aging in Normal Human Dermal Fibroblast cell (NHDF) cells and mouse skin models. We investigated the effects of the aging process in vitro and in vivo. DFRtreated NHDF cells showed a concentration-dependent increase in the expression of extracellular matrix (ECM) proteins (Collagen-2.5-fold increase at 50 µg/ml, Elastin-1.5-fold increase at 1µg/ml) as well as an increase in proteins related to cell survival, differentiation, and development, while expression of aging proteins such as matrix metalloproteinase 3 (MMP-3) was decreased (5-fold decrease at 50 µg/ml). DFR treatment also led to enhanced expression of antioxidant proteins such as nuclear factor erythroid 2-related factor 2 (10-fold increase at 50 µg/ml) and heme oxygenase 1 (1.5-fold increase at 25 µg/ml). To further investigate the antioxidative effects of DFR extracts, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities were also evaluated. DFR extracts improved wound healing and resulted in increased expression of ECM proteins, while enzymes involved in collagen degradation, including MMP-3, were decreased in NHDF cells as well as in a mouse model. This study demonstrates the anti-aging, antioxidant, and wound healing properties of DFR extracts. Therefore, DFR extracts present may facilitate skin protection and care.

Alpha-Methylacyl-CoA Racemase (AMACR), a Potential New Biomarker for Glioblastoma.

Alpha-Methylacyl-CoA racemase (AMACR), which was initially discovered as a prostate cancer marker, is critical for the chiral inversion mechanism of branched-chain fatty acids. However, the function of AMACR in brain tumors has not been investigated. In this study, AMACR appeared to be involved in glioblastoma. The protein and mRNA levels of AMACR were highly elevated in glioblastoma. Downregulation of AMACR inhibited cell proliferation. Comprehensive analysis of the public REMBRANDT GBM dataset also confirmed that the level of AMACR expression was correlated with the clinical prognosis of glioma patients. In summary, these findings indicate that AMACR expression is increased in a glioblastoma cell line and glioma patients, suggesting that AMACR might be a potential diagnostic marker and therapeutic target for cancer, including glioma.

Current Knowledge on the Function of α-Methyl Acyl-CoA Racemase in Human Diseases.

Branched chain fatty acids perform very important functions in human diet and drug metabolism. they cannot be metabolized in mitochondria and are instead processed and degraded in peroxisomes due to the presence of methyl groups on the carbon chains. Oxidative degradation pathways for lipids include α- and ß-oxidation and several pathways. In all metabolic pathways, α-methyl acyl-CoA racemase (AMACR) plays an essential role by regulating the metabolism of lipids and drugs. AMACR regulates ß-oxidation of branched chain lipids in peroxisomes and mitochondria and promotes chiral reversal of 2-methyl acids. AMACR defects cause sensory-motor neuronal and liver abnormalities in humans. These phenotypes are inherited and are caused by mutations in AMACR. In addition, AMACR has been found to be overexpressed in prostate cancer. In addition, the protein levels of AMACR have increased significantly in many types of cancer. Therefore, AMACR may be an important marker in tumors. In this review, a comprehensive overview of AMACR studies in human disease will be described.

Revisiting the Warburg Effect: Diet-Based Strategies for Cancer Prevention.

It is widely acknowledged that cancer cell energy metabolism relies mainly on anaerobic glycolysis; this phenomenon is described as the Warburg effect. However, whether the Warburg effect is caused by genetic dysregulation in cancer or is the cause of cancer remains unknown. The exact reasons and physiology of this abnormal metabolism are unclear; therefore, many researchers have attempted to reduce malignant cell growth in tumors in preclinical and clinical studies. Anticancer strategies based on the Warburg effect have involved the use of drug compounds and dietary changes. We recently reviewed applications of the Warburg effect to understand the benefits of this unusual cancer-related metabolism. In the current article, we summarize diet strategies for cancer treatment based on the Warburg effect.

FCHO1560-571 peptide, a PKB kinase motif, inhibits tumor progression.

BACKGROUND: Cell division is regulated by protein kinase B (PKB)-mediated FCH domain only 1 (FCHO1) phosphorylation. METHODS: FCHO1560-571, a synthetic water-soluble peptide, was generated from the PKB substrate motif 560PPRRLRSRKVSC571 found in the human FCHO1 protein. RESULTS: In this study, we found that in vitro FCHO1560-571 inhibits cell proliferation via PKB/ERK/SMAD4 pathways in KRAS-mutated A549 lung cancer cells. In addition, FCHO1560-571, at effective doses of 15 and 30 mg/kg, significantly suppressed tumor growth and decreased the size and weight of tumors in A549-xenograft mice. CONCLUSION: These results suggest that the FCHO1560-571 peptide could be a potential therapy for lung cancer.

Yin Yang 1 is required for PHD finger protein 20-mediated myogenic differentiation in vitro and in vivo.

The development of skeletal muscle requires progression of a highly ordered cascade of events comprising myogenic lineage commitment, myoblast proliferation, and terminal differentiation. The process of myogenesis is controlled by several myogenic transcription factors that act as terminal effectors of signaling cascades and produce appropriate developmental stage-specific transcripts. PHD finger protein 20 (PHF20) is a multidomain protein and subunit of a lysine acetyltransferase complex that acetylates histone H4 and p53, but its function is unclear. Notably, it has been reported that PHF20 knockout mice die shortly after birth and display a wide variety of phenotypes within the skeletal and hematopoietic systems. Therefore, the putative role of PHF20 in myogenic differentiation was further investigated. In the present study, we found that protein and mRNA expression levels of PHF20 were decreased during myogenic differentiation in C2C12 cells. At the same time, Yin Yang 1 (YY1) was also decreased during myogenic differentiation. PHF20 overexpression increased YY1 expression during myogenic differentiation, together with a delay in MyoD expression. PHF20 expression enhanced the transcriptional activity of YY1 while shRNA-mediated depletion of PHF20 resulted in the reduction of YY1 promoter activity in C2C12 cells. In addition, PHF20 directly bounds to the YY1 promoter in C2C12 cells. In a similar manner, YY1 expression was elevated while myosin heavy chain expression was decreased in PHF20 transgenic (TG) mice. Histological analysis revealed abnormalities in the shape and length of muscles in PHF20-TG mice. Furthermore, PHF20-TG muscles slowly regenerated after cardiotoxin injection, indicating that PHF20 affected muscle differentiation and regeneration after injury in vivo. Taken together, these results suggested that PHF20 plays an important role in myogenic differentiation by regulating YY1.

Myristoylated TMEM39AS41, a cell-permeable peptide, causes lung cancer cell death.

Lung cancer is the most common cause of cancer-associated death worldwide. Most patients with non-small cell lung cancer die within several years of the initial diagnosis, and new therapies are desperately needed. Transmembrane protein (TMEM) 39AS41, a synthetic peptide, was generated from the protein kinase B substrate motif 34GLRNRNGSAIGLPVP48 found in the human TMEM39A protein. Myristic acid was conjugated to the N-terminus of the peptide to confer cell permeability. In this study, we found that in vitro TMEM39AS41 peptide led to cell death via inhibition of inflammation/autophagy pathways in KRAS-mutated cell and tissues. In addition, TMEM39A, at a dose of 30 mg/kg, significantly suppressed tumor growth in KRASLA1 non-small cell lung cancer mice. These results suggest that the TMEM39AS41 peptide could have therapeutic potential for lung cancer.

Relationship Between Ginsenoside Rg3 and Metabolic Syndrome.

Metabolic syndrome is an important public health issue and is associated with a more affluent lifestyle. Many studies of metabolic syndrome have been reported, but its pathogenesis remains unclear and there is no effective treatment. The ability of natural compounds to ameliorate metabolic syndrome is currently under investigation. Unlike synthetic chemicals, such natural products have proven utility in various fields. Recently, ginsenoside extracted from ginseng and ginseng root are representative examples. For example, ginseng is used in dietary supplements and cosmetics. In addition, various studies have reported the effects of ginsenoside on metabolic syndromes such as obesity, diabetes, and hypertension. In this review, we describe the potential of ginsenoside Rg3, a component of ginseng, in the treatment of metabolic syndrome.

1,2-Dichloropropane (1,2-DCP)-Induced Angiogenesis in Dermatitis.

1,2-Dichloropropane (1,2-DCP) has been used as an industrial solvent and a chemical intermediate, as well as in soil fumigants. Human exposure may occur during its production and industrial use. The target organs of 1,2-DCP are the eyes, respiratory system, liver, kidneys, central nervous system, and skin. Repeated or prolonged contact may cause skin sensitization. In this study, 1,2-DCP was dissolved in corn oil at 0, 2.73, 5.75, and 8.75 mL/kg. The skin of mice treated with 1,2-DCP was investigated using western blotting, hematoxylin and eosin staining, and immunohistochemistry. 1,2-DCP was applied to the dorsal skin and both ears of C57BL/6J mice. The thickness of ears and the epidermis increased significantly following treatment, and the appearance of blood vessels was observed in the dorsal skin. Additionally, the expression of vascular endothelial growth factor, which is tightly associated with neovascularization, increased significantly. The levels of protein kinase-B (PKB), phosphorylated PKB, mammalian target of rapamycin (mTOR), and phosphorylated mTOR, all of which are key components of the phosphoinositide 3-kinase/PKB/mTOR signaling pathway, were also enhanced. Taken together, 1,2-DCP induced angiogenesis in dermatitis through the PI3K/PKB/mTOR pathway in the skin.

A new role for the ginsenoside RG3 in antiaging via mitochondria function in ultraviolet-irradiated human dermal fibroblasts.

BACKGROUND: The efficacy of ginseng, the representative product of Korea, and its chemical effects have been well investigated. The ginsenoside RG3 has been reported to exhibit apoptotic, anticancer, and antidepressant-like effects. METHODS: In this report, the putative effect of RG3 on several cellular function including cell survival, differentiation, development and aging process were evaluated by monitoring each specific marker. Also, mitochondrial morphology and function were investigated in ultraviolet (UV)-irradiated normal human dermal fibroblast cells. RESULTS: RG3 treatment increased the expression of extracellular matrix proteins, growth-associated immediate-early genes, and cell proliferation genes in UV-irradiated normal human dermal fibroblast cells. And, RG3 also resulted in enhanced expression of antioxidant proteins such as nuclear factor erythroid 2-related factor-2 and heme oxygenase-1. In addition, RG3 affects the morphology of UV-induced mitochondria and plays a role in protecting mitochondrial dysfunction. CONCLUSIOIN: RG3 restores mitochondrial adenosine triphosphate (ATP) and membrane potential via its antioxidant effects in skin cells damaged by UV irradiation, leading to an increase in proteins linked with the extracellular matrix, cell proliferation, and antioxidant activity.

LETM1 is required for mitochondrial homeostasis and cellular viability (Review).

Leucine zipper/EF­hand­containing transmembrane protein 1 (LETM1) has been identified as the gene responsible for Wolf­Hirschhorn syndrome (WHS), which is characterized by intellectual disability, epilepsy, growth delay and craniofacial dysgenesis. LETM1 is a mitochondrial inner membrane protein that encodes a homolog of the yeast protein Mdm38, which is involved in mitochondrial morphology. In the present review, the importance of LETM1 in WHS and its role within the mitochondrion was explored. LETM1 governs the mitochondrion ion channel and is involved in mitochondrial respiration. Recent studies have reported that LETM1 acts as a mitochondrial Ca2+/H+ antiporter. LETM1 has also been identified as a K+/H+ exchanger, and serves a role in Mg2+ homeostasis. The function of LETM1 in mitochondria regulation is regulated by its binding partners, carboxyl­terminal modulator protein and mitochondrial ribosomal protein L36. Therefore, we describe the remarkable role of LETM1 in mitochondrial network physiology and its function in mitochondrion­mediated cell death. In the context of these findings, we suggest that the participation of LETM1 in tumorigenesis through the alteration of cancer metabolism should be investigated. This review provides a comprehensive description of LETM1 function, which is required for mitochondrial homeostasis and cellular viability.

S6 kinase 1 plays a key role in mitochondrial morphology and cellular energy flow.

Mitochondrial morphology, which is associated with changes in metabolism, cell cycle, cell development and cell death, is tightly regulated by the balance between fusion and fission. In this study, we found that S6 kinase 1 (S6K1) contributes to mitochondrial dynamics, homeostasis and function. Mouse embryo fibroblasts lacking S6K1 (S6K1-KO MEFs) exhibited more fragmented mitochondria and a higher level of Dynamin related protein 1 (Drp1) and active Drp1 (pS616) in both whole cell extracts and mitochondrial fraction. In addition, there was no evidence for autophagy and mitophagy induction in S6K1 depleted cells. Glycolysis and mitochondrial respiratory activity was higher in S6K1-KO MEFs, whereas OxPhos ATP production was not altered. However, inhibition of Drp1 by Mdivi1 (Drp1 inhibitor) resulted in higher OxPhos ATP production and lower mitochondrial membrane potential. Taken together the depletion of S6K1 increased Drp1-mediated fission, leading to the enhancement of glycolysis. The fission form of mitochondria resulted in lower yield for OxPhos ATP production as well as in higher mitochondrial membrane potential. Thus, these results have suggested a potential role of S6K1 in energy metabolism by modulating mitochondrial respiratory capacity and mitochondrial morphology.