Sodium citrate targeting Ca2+/CAMKK2 pathway exhibits anti-tumor activity through inducing apoptosis and ferroptosis in ovarian cancer.

INTRODUCTION: Ovarian cancer (OC) is known for its high mortality rate. Although sodium citrate has anti-tumor effects in various cancers, its effect and mechanism in OC remain unclear. OBJECTIVES: To analyze the inhibitory effect of sodium citrate on ovarian cancer cells and the underlying mechanism. METHODS: Cell apoptosis was examined by TUNEL staining, flow cytometry, and ferroptosis was examined intracellular Fe2+, MDA, LPO assays, respectively. Cell metabolism was examined by OCR and ECAR measurements. Immunoblotting and immunoprecipitation were used to elucidate the mechanism. RESULTS: This study suggested that sodium citrate not only promoted ovarian cancer cell apoptosis but also triggeredferroptosis, manifested as elevated levels of Fe2+, LPO, MDA andlipid ROS production. On one hand, sodium citrate treatment led to a decrease of Ca2+ content in the cytosol by chelatingCa2+, which further inhibited the Ca2+/CAMKK2/AKT/mTOR signaling, thereby suppressing HIF1α-dependent glycolysis pathway and inducing cell apoptosis. On the other hand, the chelation of Ca2+ by sodium citrate resulted in inactivation of CAMKK2 and AMPK, leading to increase of NCOA4-mediated ferritinophagy, causing increased intracellular Fe2+ levels. More importantly, the inhibition of Ca2+/CAMKK2/AMPK signaling pathway reduced the activity of the MCU and Ca2+ concentration within the mitochondria, resulting in an increase in mitochondrial ROS. Additionally, metabolomic analysis indicated that sodium citrate treatment significantly increased de novo lipid synthesis. Altogether, these factors contributed to ferroptosis. As expected, Ca2+ supplementation successfully reversed the cell death and decreased tumor growth induced by sodium citrate. Inspiringly, it was found that coadministration of sodium citrate increased the sensitivity of OC cells to chemo-drugs. CONCLUSION: These results revealed that the sodium citrate exerted its anti-cancer activity by inhibiting Ca2+/CAMKK2-dependent cell apoptosis and ferroptosis. Sodium citrate will hopefully serve as a prospective compound for OC treatment and for improvingthe efficacy of chemo-drugs.

The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions.

Due to insufficient and defective vascularization, the tumor microenvironment is often nutrient-depleted. LDHA has been demonstrated to play a tumor-promoting role by facilitating the glycolytic process. However, whether and how LDHA regulates cell survival in the nutrient-deficient tumor microenvironment is still unclear. Here, we sought to investigate the role and mechanism of LDHA in regulating cell survival and proliferation under energy stress conditions. Our results showed that the aerobic glycolysis levels, cell survival and proliferation of cervical cancer cells decreased significantly after inhibition of LDHA under normal culture condition while LDHA deficiency greatly inhibited glucose starvation-induced ferroptosis and promoted cell proliferation and tumor formation under energy stress conditions. Mechanistic studies suggested that glucose metabolism shifted from aerobic glycolysis to mitochondrial OXPHOS under energy stress conditions and LDHA knockdown increased accumulation of pyruvate in the cytosol, which entered the mitochondria and upregulated the level of oxaloacetate by phosphoenolpyruvate carboxylase (PC). Importantly, the increase in oxaloacetate production after absence of LDHA remarkably activated AMP-activated protein kinase (AMPK), which increased mitochondrial biogenesis and mitophagy, promoted mitochondrial homeostasis, thereby decreasing ROS level. Moreover, repression of lipogenesis by activation of AMPK led to elevated levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which effectively resisted ROS-induced cell ferroptosis and enhanced cell survival under energy stress conditions. These results suggested that LDHA played an opposing role in survival and proliferation of cervical cancer cells under energy stress conditions, and inhibition of LDHA may not be a suitable treatment strategy for cervical cancer.

TSP50 Attenuates DSS-Induced Colitis by Regulating TGF-ß Signaling Mediated Maintenance of Intestinal Mucosal Barrier Integrity.

The integrity of the intestinal mucosal barrier is crucial for protecting the intestinal epithelium against invasion by commensal bacteria and pathogens, thereby combating colitis. The investigation revealed that the absence of TSP50 compromised the integrity of the intestinal mucosal barrier in murine subjects. This disruption facilitated direct contact between intestinal bacteria and the intestinal epithelium, thereby increasing susceptibility to colitis. Mechanistic analysis indicated that TSP50 deficiency in intestinal stem cells (ISCs) triggered aberrant activation of the TGF-ß signaling pathway and impeded the differentiation of goblet cells in mice, leading to impairment of mucosal permeability. By inhibiting the TGF-ß pathway, the functionality of the intestinal mucosal barrier is successfully restored and mitigated colitis in TSP50-deficient mice. In conclusion, TSP50 played a crucial role in maintaining the intestinal mucosal barrier function and exhibited the preventive effect against the development of colitis by regulating the TGF-ß signaling pathway.

FAT4 overexpression promotes antitumor immunity by regulating the ß-catenin/STT3/PD-L1 axis in cervical cancer.

BACKGROUND: FAT4 (FAT Atypical Cadherin 4) is a member of the cadherin-associated protein family, which has been shown to function as a tumor suppressor by inhibiting proliferation and metastasis. The Wnt/ß-catenin pathway activation is highly associated with PD-L1-associated tumor immune escape. Here, we report the mechanism by which FAT4 overexpression regulates anti-tumor immunity in cervical cancer by inhibiting PD-L1 N-glycosylation and cell membrane localization in a ß-catenin-dependent manner. METHODS: FAT4 expression was first detected in cervical cancer tissues and cell lines. Cell proliferation, clone formation, and immunofluorescence were used to determine the tumor suppressive impact of FAT4 overexpression in vitro, and the findings were confirmed in immunodeficient and immunocomplete mice xenografts. Through functional and mechanistic experiments in vivo and in vitro, we investigated how FAT4 overexpression affects the antitumor immunity via the ß-catenin/STT3/PD-L1 axis. RESULTS: FAT4 is downregulated in cervical cancer tissues and cell lines. We determined that FAT4 binds to ß-catenin and antagonizes its nuclear localization, promotes phosphorylation and degradation of ß-catenin by the degradation complexes (AXIN1, APC, GSK3ß, CK1). FAT4 overexpression decreases programmed death-ligand 1 (PD-L1) mRNA expression at the transcriptional level, and causes aberrant glycosylation of PD-L1 via STT3A at the post-translational modifications (PTMs) level, leading to its endoplasmic reticulum (ER) accumulation and polyubiquitination-dependent degradation. We found that FAT4 overexpression promotes aberrant PD-L1 glycosylation and degradation in a ß-catenin-dependent manner, thereby increasing cytotoxic T lymphocyte (CTL) activity in immunoreactive mouse models. CONCLUSIONS: These findings address the basis of Wnt/ß-catenin pathway activation in cervical cancer and provide combination immunotherapy options for targeting the FAT4/ß-catenin/STT3/PD-L1 axis. Schematic cartoons showing the antitumor immunity mechanism of FAT4. (left) when Wnts bind to their receptors, which are made up of Frizzled proteins and LRP5/6, the cytoplasmic protein DVL is activated, inducing the aggregation of degradation complexes (AXIN, GSK3ß, CK1, APC) to the receptor. Subsequently, stable ß-catenin translocates into the nucleus and binds to TCF/LEF and TCF7L2 transcription factors, leading to target genes transcription. The catalytically active subunit of oligosaccharyltransferase, STT3A, enhances PD-L1 glycosylation, and N-glycosylated PD-L1 translocates to the cell membrane via the ER-to-Golgi pathway, resulting in immune evasion. (Right) FAT4 exerts antitumor immunity mainly through following mechanisms: (i) FAT4 binds to ß-catenin and antagonizes its nuclear localization, promotes phosphorylation and degradation of ß-catenin by the degradation complexes (AXIN1, APC, GSK3ß, CK1); (ii) FAT4 inhibits PD-L1 and STT3A transcription in a ß-catenin-dependent manner and induces aberrant PD-L1 glycosylation and ubiquitination-dependent degradation; (iii) Promotes activation of cytotoxic T lymphocytes (CTL) and infiltration into the tumor microenvironment.

Tectorigenin targets PKACα to promote GLUT4 expression in skeletal muscle and improve insulin resistance in vitro and in vivo.

The decreased expression and dysfunction of glucose transporter 4 (GLUT4), the insulin-responsive glucose transporter, are closely related to the occurrence of insulin resistance (IR). To improve the expression of GLUT4 may represent a promising strategy to prevent and treat IR and type 2 diabetes (T2DM). Here, we demonstrate that the natural compound tectorigenin (TG) enhances GLUT4 expression, glucose uptake and insulin responsiveness via activating AMP-activated protein kinase (AMPK)/myocyte enhancer factor 2 (MEF2) signaling in both normal and IR skeletal muscle cells and tissues. Accordingly, prophylactic and therapeutic uses of TG can significantly ameliorate IR and hyperglycemia in T2DM mice. Mechanistically, we identify protein kinase A catalytic subunit α (PKACα) as the target of TG to increase GLUT4 expression and TG-PKACα binding promotes the dissociation of PKACα from the regulatory subunits, leading to the activation of PKA/AMPK signaling. PKACα knockdown in local quadriceps muscles almost completely abolished the therapeutic effects of TG on IR and T2DM, as well as the enhancement on AMPK signaling and GLUT4 expression in skeletal muscle. This study supports TG as a new drug candidate to treat IR and its related diseases, but also enriches our knowledge of PKA signaling in glucose metabolism in skeletal muscle.

Transcriptome sequencing identifies prognostic genes involved in gastric adenocarcinoma.

Gastric adenocarcinoma (GAC) is one of the world's most lethal malignant tumors. It has been established that the occurrence and progression of GAC are linked to molecular changes. However, the pathogenesis mechanism of GAC remains unclear. In this study, we sequenced 6 pairs of GAC tumor tissues and adjacent normal tissues and collected GAC gene expression profile data from the TCGA database. Analysis of this data revealed 465 differentially expressed genes (DEGs), of which 246 were upregulated and 219 were downregulated. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that DEGs were observably enriched in ECM-receptor interaction, protein digestion and absorption, and gastric acid secretion pathways. Six key genes (MATN3, COL1A1, COL5A2, P4HA3, SERPINE1 and VCAN) associated with poor GAC prognosis were screened from the protein‒protein interaction (PPI) network by survival analysis, and P4HA3 and MATN3 have rarely been reported to be associated with GAC. We further analyzed the function of P4HA3 in the GAC cell line SGC-7901 by RT‒qPCR, MTT, flow cytometry, colony formation, wound healing, Transwell and western blot assays. We found that P4HA3 was upregulated in the SGC-7901 cell line versus normal control cells. The outcomes of the loss-of-function assay illustrated that P4HA3 significantly enhanced the ability of GAC cells to proliferate and migrate. This study provides a new basis for the selection of prognostic markers and therapeutic targets for GAC.

STS1 and STS2 Phosphatase Inhibitor Baicalein Enhances the Expansion of Hematopoietic and Progenitor Stem Cells and Alleviates 5-Fluorouracil-Induced Myelosuppression.

STS1 and STS2, as the protein phosphatases that dephosphorylate FLT3 and cKIT, negatively regulate the self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPCs). To obtain the small molecule inhibitors of STS1/STS2 phosphatase activity used to expand HSPCs both in vitro and in vivo, we establish an in vitro phosphatase assay using the recombinant proteins of the STS1/STS2 histidine phosphatase (HP) domain, by which we screened out baicalein (BC) as one of the effective inhibitors targeting STS1 and STS2. Then, we further demonstrate the direct binding of BC with STS1/STS2 using molecular docking and capillary electrophoresis and verify that BC can restore the phosphorylation of FLT3 and cKIT from STS1/STS2 inhibition. In a short-term in vitro culture, BC promotes profound expansion and enhances the colony-forming capacity of both human and mouse HSPCs along with the elevation of phospho-FLT3 and phospho-cKIT levels. Likewise, in vivo administration with BC significantly increases the proportions of short-term hematopoietic stem cells (ST-HSCs), multipotent progenitors (MPPs) and especially long-term HSCs (LT-HSCs) in healthy mouse bone marrow and increases the numbers of colony-forming units (CFU) formed by HSPCs as well. More importantly, pre-administration of BC significantly enhances the survival of mice with lethal 5-fluorouracil (5-FU) injection due to the alleviation of 5-FU-induced myelosuppression, as evidenced by the recovery of bone marrow histologic injury, the increased proportions of LT-HSCs, ST-HSCs and MPPs, and enhanced colony-forming capacity. Collectively, our study not only suggests BC as one of the small molecule candidates to stimulate HSPC expansion both in vitro and in vivo when needed in either physiologic or pathologic conditions, but also supports STS1/STS2 as potential therapeutic drug targets for HSPC expansion and hematopoietic injury recovery.

FRMD3 inhibits the growth and metastasis of breast cancer through the ubiquitination-mediated degradation of vimentin and subsequent impairment of focal adhesion.

Recurrence and metastasis are the main causes of breast cancer (BRCA)-related death and remain a challenge for treatment. In-depth research on the molecular mechanisms underlying BRCA progression has been an important basis for developing precise biomarkers and therapy targets for early prediction and treatment of progressed BRCA. Herein, we identified FERM domain-containing protein 3 (FRMD3) as a novel potent BRCA tumor suppressor which is significantly downregulated in BRCA clinical tissue and cell lines, and low FRMD3 expression has been closely associated with progressive BRCA and shortened survival time in BRCA patients. Overexpression and knockdown experiments have revealed that FRMD3 significantly inhibits BRCA cell proliferation, migration, and invasion in vitro and suppresses BRCA xenograft growth and metastasis in vivo as well. Mechanistically, FRMD3 can interact with vimentin and ubiquitin protein ligase E3A(UBE3A) to induce the polyubiquitin-mediated proteasomal degradation of vimentin, which subsequently downregulates focal adhesion complex proteins and pro-cancerous signaling activation, thereby resulting in cytoskeletal rearrangement and defects in cell morphology and focal adhesion. Further evidence has confirmed that FRMD3-mediated vimentin degradation accounts for the anti-proliferation and anti-metastasis effects of FRMD3 on BRCA. Moreover, the N-terminal ubiquitin-like domain of FRMD3 has been identified as responsible for FRMD3-vimentin interaction through binding the head domain of vimentin and the truncated FRMD3 with the deletion of ubiquitin-like domain almost completely loses the anti-BRCA effects. Taken together, our study indicates significant potential for the use of FRMD3 as a novel prognosis biomarker and a therapeutic target of BRCA and provides an additional mechanism underlying the degradation of vimentin and BRCA progression.

Ursolic Acid Targets Glucosyltransferase and Inhibits Its Activity to Prevent Streptococcus mutans Biofilm Formation.

Streptococcus mutans (S. mutans), the prime pathogen of dental caries, can secrete glucosyltransferases (GTFs) to synthesize extracellular polysaccharides (EPSs), which are the virulence determinants of cariogenic biofilms. Ursolic acid, a type of pentacyclic triterpene natural compound, has shown potential antibiofilm effects on S. mutans. To investigate the mechanisms of ursolic acid-mediated inhibition of S. mutans biofilm formation, we first demonstrated that ursolic acid could decrease the viability and structural integrity of biofilms, as evidenced by XTT, crystal violet, and live/dead staining assays. Then, we further revealed that ursolic acid could compete with the inherent substrate to occupy the catalytic center of GTFs to inhibit EPS formation, and this was confirmed by GTF activity assays, computer simulations, site-directed mutagenesis, and capillary electrophoresis (CE). In conclusion, ursolic acid can decrease bacterial viability and prevent S. mutans biofilm formation by binding and inhibiting the activity of GTFs.

Discovery and Verification of Key Liver Cancer Genes and Alternative Splicing Events Based on Second-Generation Sequencing Data Analysis.

Hepatocellular carcinoma (HCC) is the most common malignant liver disease in the world. Existing screening and early diagnosis methods are not highly sensitive for HCC, and patients are likely to develop the disease to the middle and advanced stages before being diagnosed. Therefore, finding new and efficient diagnosis and treatment methods has become an urgent problem. We aimed at finding and verifying new liver cancer markers by combining informatics analysis with experimental exploration to provide new ideas and methods for the diagnosis and treatment of clinical liver cancer. We used two different bioinformatic pipelines to analyze sequencing data of clinical liver cancer samples and identify differentially expressed genes and key variants after combining them with The Cancer Genome Atlas sequencing data. Then, we explored the functions and mechanisms of the key variants to identify potential liver cancer markers. Through bioinformatic analysis of sequencing data, 139 differentially expressed genes were found, including 53 upregulated genes and 86 downregulated genes. Through enrichment and alternative splicing event analysis of sequencing data, we found nine key variants with exon skipping events. Metallothionein 1E (MT1E)-203 was found to be a key variant that influenced cell proliferation through the p53 cell cycle pathway through cell viability and proliferation assays, and MT1E-203 lost the ability to bind two zinc ions due to exon skipping according to the structure prediction of MT1E-203. MT1E-203 is a potential biomarker for HCC and may play an important role in the diagnosis and treatment of HCC.

Discovery of a novel HDACi structure that inhibits the proliferation of ovarian cancer cells in vivo and in vitro.

Histone deacetylases (HDACs) exhibit increased expression in cancer and promote oncogenesis via the acetylation of or interactions with key transcriptional regulators. HDAC inhibitors (HDACis) decrease HDAC activity to selectively inhibit the occurrence and development of tumors. Our study screened and obtained a new HDACi structure. In vitro experiments have showed that among the leads, Z31216525 significantly inhibited the proliferation and induced the apoptosis of epithelial ovarian cancer (EOC) cells. In vivo experiments demonstrated that compared to the control, Z31216525 significantly inhibited tumor growth and showed very low toxicity. Further mechanistic studies revealed that Z31216525 may exert an antitumor effect by inhibiting the expression of the c-Myc gene. Collectively, our studies identified a novel HDACi that is expected to become a new potential therapeutic drug for EOC and has important value for the design of new HDACi structures.

Analysis of Bulk RNA Sequencing Data Reveals Novel Transcription Factors Associated With Immune Infiltration Among Multiple Cancers.

Tumor-infiltrating immune cells shape the tumor microenvironment and are closely related to clinical outcomes. Several transcription factors (TFs) have also been reported to regulate the antitumor activity and immune cell infiltration. This study aimed to quantify the populations of different immune cells infiltrated in tumor samples based on the bulk RNA sequencing data obtained from 50 cancer patients using the CIBERSORT and the EPIC algorithm. Weighted gene coexpression network analysis (WGCNA) identified eigengene modules strongly associated with tumorigenesis and the activation of CD4+ memory T cells, dendritic cells, and macrophages. TF genes FOXM1, MYBL2, TAL1, and ERG are central in the subnetworks of the eigengene modules associated with immune-related genes. The analysis of The Cancer Genome Atlas (TCGA) cancer data confirmed these findings and further showed that the expression of these potential TF genes regulating immune infiltration, and the immune-related genes that they regulated, was associated with the survival of patients within multiple cancers. Exome-seq was performed on 24 paired samples that also had RNA-seq data. The expression quantitative trait loci (eQTL) analysis showed that mutations were significantly more frequent in the regions flanking the TF genes compared with those of non-TF genes, suggesting a driver role of these TF genes regulating immune infiltration. Taken together, this study presented a practical method for identifying genes that regulate immune infiltration. These genes could be potential biomarkers for cancer prognosis and possible therapeutic targets.

AGTAR: A novel approach for transcriptome assembly and abundance estimation using an adapted genetic algorithm from RNA-seq data.

BACKGROUND: Recently, the rapid development of RNA-seq technologies has accelerated transcriptomics research. The accurate identification and quantification of transcripts based on RNA-seq data will facilitate the exploration of various potential biological mechanisms. However, due to the limitations of the current data analysis tools and RNA-seq technologies, full and accurate reconstruction of the transcriptome still faces many challenges. RESULTS: We developed the adapted genetic algorithm (AGTAR) program, which can reliably assemble transcriptomes and estimate abundance based on RNA-seq data with or without genome annotation files. We defined a new concept, isoform junction abundance, to help enhance the accuracy of isoform identification and quantification. Isoform abundance and isoform junction abundance are estimated by an adapted genetic algorithm. The crossover and mutation probabilities of the algorithm can be adaptively adjusted to effectively prevent premature convergence. Both simulated and real data indicated that AGTAR's comprehensive ability to assemble transcripts is significantly superior to that achievable by the currently widely used tools with similar functions. CONCLUSIONS: AGTAR is a tool for identifying and quantifying transcripts from RNA-seq data. It has the advantages of higher accuracy and ease of use. The AGTAR package is freely available at https://github.com/v4yuezi/AGTAR.git.

SUVA: splicing site usage variation analysis from RNA-seq data reveals highly conserved complex splicing biomarkers in liver cancer.

Most of the current alternative splicing (AS) analysis tools are powerless to analyse complex splicing. To address this, we developed SUVA (Splice sites Usage Variation Analysis) that decomposes complex splicing events into five types of splice junction pairs. By analysing real and simulated data, SUVA showed higher sensitivity and accuracy in detecting AS events than the compared methods. Notably, SUVA detected extensive complex AS events and screened out 69 highly conserved and dominant AS events associated with cancer. The cancer-associated complex AS events in FN1 and the co-regulated RNA-binding proteins were significantly correlated with patient survival.

Stevioside Activates AMPK to Suppress Inflammation in Macrophages and Protects Mice from LPS-Induced Lethal Shock.

Stevioside, a diterpenoid glycoside, is widely used as a natural sweetener; meanwhile, it has been proven to possess various pharmacological properties as well. However, until now there were no comprehensive evaluations focused on the anti-inflammatory activity of stevioside. Thus, the anti-inflammatory activities of stevioside, both in macrophages (RAW 264.7 cells, THP-1 cells, and mouse peritoneal macrophages) and in mice, were extensively investigated for the potential application of stevioside as a novel anti-inflammatory agent. The results showed that stevioside was capable of down-regulating lipopolysaccharide (LPS)-induced expression and production of pro-inflammatory cytokines and mediators in macrophages from different sources, such as IL-6, TNF-α, IL-1ß, iNOS/NO, COX2, and HMGB1, whereas it up-regulated the anti-inflammatory cytokines IL-10 and TGF-ß1. Further investigation showed that stevioside could activate the AMPK -mediated inhibition of IRF5 and NF-κB pathways. Similarly, in mice with LPS-induced lethal shock, stevioside inhibited release of pro-inflammatory factors, enhanced production of IL-10, and increased the survival rate of mice. More importantly, stevioside was also shown to activate AMPK in the periphery blood mononuclear cells of mice. Together, these results indicated that stevioside could significantly attenuate LPS-induced inflammatory responses both in vitro and in vivo through regulating several signaling pathways. These findings further strengthened the evidence that stevioside may be developed into a therapeutic agent against inflammatory diseases.

KIAA1217 Promotes Epithelial-Mesenchymal Transition and Hepatocellular Carcinoma Metastasis by Interacting with and Activating STAT3.

The survival and prognosis of hepatocellular carcinoma (HCC) are poor, mainly due to metastasis. Therefore, insights into the molecular mechanisms underlying HCC invasion and metastasis are urgently needed to develop a more effective antimetastatic therapy. Here, we report that KIAA1217, a functionally unknown macromolecular protein, plays a crucial role in HCC metastasis. KIAA1217 expression was frequently upregulated in HCC cell lines and tissues, and high KIAA1217 expression was closely associated with shorter survival of patients with HCC. Overexpression and knockdown experiments revealed that KIAA1217 significantly promoted cell migration and invasion by inducing epithelial-mesenchymal transition (EMT) in vitro. Consistently, HCC cells overexpressing KIAA1217 exhibited markedly enhanced lung metastasis in vivo. Mechanistically, KIAA1217 enhanced EMT and accordingly promoted HCC metastasis by interacting with and activating JAK1/2 and STAT3. Interestingly, KIAA1217-activated p-STAT3 was retained in the cytoplasm instead of translocating into the nucleus, where p-STAT3 subsequently activated the Notch and Wnt/ß-catenin pathways to facilitate EMT induction and HCC metastasis. Collectively, KIAA1217 may function as an adaptor protein or scaffold protein in the cytoplasm and coordinate multiple pathways to promote EMT-induced HCC metastasis, indicating its potential as a therapeutic target for curbing HCC metastasis.

Fas and GIT1 signalling in the prefrontal cortex mediate behavioural sensitization to methamphetamine in mice.

PURPOSE: Repeated methamphetamine (METH) administration in mice readily produces behavioural sensitization, but the underlying mechanisms remain elusive. The present research aimed to identify new targets affecting METH-induced behavioural sensitization. METHODS: We first established a mouse model of METH-induced behavioural sensitization. To characterize the animal model, we performed behavioural tests at different stages of behavioural sensitization and simultaneously detected changes in several neurotransmitters in the prefrontal cortex (PFC). Next, we perfromed RNA sequencing (RNA-seq) to screen new targets, which were subsequently and verified by RT-PCR and western blot. Finally, we confirmed the roles of the new targets in METH-induced behavioural sensitization by injection of overexpressed lentiviruses and further detected related protein levels by western blot and histological changes by haematoxylin and eosin (HE) staining. RESULTS: We successfully established a mouse model of METH-induced behavioural sensitization. The locomotor activities of the mice changed at different stages of sensitization, accompanied by changes in the levels of DA, 5-HT, GABA and glutamate. For RNA-seq analysis, we chose Fas as target, meanwhile, we chose GIT1 as target through literature. The detection of gene expression by RT-PCR indicated that METH-sensitized mice exhibited decreased levels of Fas, MEK1 and CREB and increased levels of Erk1/2 in the PFC. Western blot analysis revealed decreased Fas, GIT1, MEK1 and phosphorylated CREB levels and increased phosphorylated Erk1/2 levels in METH-sensitized mice. Injection of Fas and GIT1 injection showed that overexpression of Fas and GIT1 inhibited the induction of METH sensitization and reversed the changes in neurotransmitter levels and related protein levels, including MEK1, phosphorylated CREB and phosphorylated Erk1/2, in METH-sensitized mice. Overexpression of Fas and GIT1 also reduced histological lesions induced by METH. CONCLUSION: The findings indicated that the development of behavioural sensitization to METH may be mediated by Fas and GIT1 through the MEK1-Erk1/2-CREB pathway.

Tectorigenin enhances PDX1 expression and protects pancreatic ß-cells by activating ERK and reducing ER stress.

Pancreas/duodenum homeobox protein 1 (PDX1) is an important transcription factor that regulates islet ß-cell proliferation, differentiation, and function. Reduced expression of PDX1 is thought to contribute to ß-cell loss and dysfunction in diabetes. Thus, promoting PDX1 expression can be an effective strategy to preserve ß-cell mass and function. Previously, we established a PDX1 promoter-dependent luciferase system to screen agents that can promote PDX1 expression. Natural compound tectorigenin (TG) was identified as a promising candidate that could enhance the activity of the promoter for the PDX1 gene. In this study, we first demonstrated that TG could promote the expression of PDX1 in ß-cells via activating extracellular signal-related kinase (ERK), as indicated by increased phosphorylation of ERK; this effect was observed under either normal or glucotoxic/lipotoxic conditions. We then found that TG could suppress induced apoptosis and improved the viability of ß-cells under glucotoxicity and lipotoxicity by activation of ERK and reduction of reactive oxygen species and endoplasmic reticulum (ER) stress. These effects held true in vivo as well: prophylactic or therapeutic use of TG could obviously inhibit ER stress and decrease islet ß-cell apoptosis in the pancreas of mice given a high-fat/high-sucrose diet (HFHSD), thus dramatically maintaining or restoring ß-cell mass and islet size, respectively. Accordingly, both prophylactic and therapeutic use of TG improved HFHSD-impaired glucose metabolism in mice, as evidenced by ameliorating hyperglycemia and glucose intolerance. Taken together, TG, as an agent promoting PDX1 expression exhibits strong protective effects on islet ß-cells both in vitro and in vivo.

Ethyl-p-methoxycinnamate enhances oct4 expression and reinforces pluripotency through the NF-κB signaling pathway.

Pluripotent stem cells are have therapeutic applications in regenerative medicine and drug discovery. However, the differentiation of stem cells in vitro hinders their large-scale production and clinical applications. The maintenance of cell pluripotency relies on a complex network of transcription factors; of these, octamer-binding transcription factor-4 (Oct4) plays a key role. This study aimed to construct an Oct4 gene promoter-driven firefly luciferase reporter and screen small-molecule compounds could maintain cell self-renewal and pluripotency. The results showed that ethyl-p-methoxycinnamate (EPMC) enhance the promoter activity of the Oct4 gene, increased the expression of Oct4 at both mRNA and protein levels, and significantly promoted the colony formation of P19 cells. These findings suggesting that EPMC could reinforce the self-renewal capacity of P19 cells. The pluripotency markers Oct4, SRY-related high-mobility-group-box protein-2, and Nanog were expressed at higher levels in EPMC-induced colonies. EPMC could promote teratoma formation and differentiation potential of P19 cells in vivo. It also enhanced self-renewal and pluripotency of human umbilical cord mesenchymal stem cells and mouse embryonic stem cells. Moreover, it significantly activated the nuclear factor kappa B (NF-κB) signaling pathway via the myeloid differentiation factor 88-dependent pathway. The expression level of Oct4 decreased after blocking the NF-κB signaling pathway, suggesting that EPMC promoted the expression of Oct4 partially through the NF-κB signaling pathway. This study indicated that EPMC could maintain self-renewal and pluripotency of stem cells.

Hypericin attenuates nonalcoholic fatty liver disease and abnormal lipid metabolism via the PKA-mediated AMPK signaling pathway in vitro and in vivo.

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and constitutes a major risk factor for progression to cirrhosis, liver failure and hepatocellular carcinoma (HCC). The occurrence of NAFLD is closely associated with abnormal lipid metabolism and implies a high risk of type 2 diabetes and cardiovascular disease. Therefore, specific and effective drugs for the prevention and treatment of NAFLD are necessary. Hypericin (HP) is one of the main active ingredients of Hypericum perforatum L., and we previously revealed its protective role in islet ß-cells and its effects against type 2 diabetes. In this study, we aimed to explore the preventive and therapeutic effects of HP against NAFLD and the underlying mechanisms in vitro and in vivo. Here, we demonstrated that HP improved cell viability by reducing apoptosis and attenuated lipid accumulation in hepatocytes both in vitro and in vivovia attenuating oxidative stress, inhibiting lipogenesis and enhancing lipid oxidization. Thus, HP exhibited significant preventive and therapeutic effects against HFHS-induced NAFLD and dyslipidemia in mice. Furthermore, we demonstrated that HP directly bound to PKACα and activated PKA/AMPK signaling to elicit its effects against NAFLD, suggesting that PKACα is one of the drug targets of HP. In addition, the enhancing effect of HP on lipolysis in adipocytes through the activation of PKACα was also elucidated. Together, the conclusions indicated that HP, of which one of the targets is PKACα, has the potential to be used as a preventive or therapeutic drug against NAFLD or abnormal lipid metabolism in the future.