Interaction between p21-activated kinase 4 and ß-catenin as a novel pathway for PTH-dependent osteoblast activation.

Parathyroid hormone (PTH) serves dual roles in bone metabolism, exhibiting both anabolic and catabolic effects. The anabolic properties of PTH have been utilized in the treatment of osteoporosis with proven efficacy in preventing fractures. Despite these benefits, PTH can be administered therapeutically for up to 2 years, and its use in patients with underlying malignancies remains a subject of ongoing debate. These considerations underscore the need for a more comprehensive understanding of the underlying mechanisms. p21-activated kinase 4 (PAK4) is involved in bone resorption and cancer-associated osteolysis; however, its role in osteoblast function and PTH action remains unknown. Therefore, in this study, we aimed to clarify the role of PAK4 in osteoblast function and its effects on PTH-induced anabolic activity. PAK4 enhanced MC3T3-E1 osteoblast viability and proliferation and upregulated cyclin D1 expression. PAK4 also augmented osteoblast differentiation, as indicated by increased mineralization found by alkaline phosphatase and Alizarin Red staining. Treatment with PTH (1-34), an active PTH fragment, stimulated PAK4 expression and phosphorylation in a protein kinase A-dependent manner. In addition, bone morphogenetic protein-2 (which is known to promote bone formation) increased phosphorylated PAK4 (p-PAK4) and PAK4 levels. PAK4 regulated the expression of both phosphorylated and total ß-catenin, which are critical for osteoblast proliferation and differentiation. Moreover, p-PAK4 directly interacted with ß-catenin, and disruption of ß-catenin's binding to T-cell factor impaired PAK4- and PTH-induced osteoblast differentiation. Our findings elucidate the effect of PAK4 on enhancing bone formation in osteoblasts and its pivotal role in the anabolic activity of PTH mediated through its interaction with ß-catenin. These insights improve the understanding of the mechanisms underlying PTH activity and should inform the development of more effective and safer osteoporosis treatments.

Strong intramolecular charge-transfer effect strengthening naphthoquinone-based chemosensor: Experimental and theoretical evaluation.

An aminophenol-linked naphthoquinone-based fluorometric and colorimetric chemosensor 2-chloro-3-((3-hydroxyphenyl) amino) naphthalene-1,4-dione (2CAN-Dione) was synthesized for selective detection of Sn2+ ion in aqueous solution. The amine and conversion of carbonyl into carboxyl groups play a vital role in the sensing mechanism when Sn2+ is added to 2CAN-Dione. Comprehensive characterization of the sensor was carried out using standard spectral and analytical approaches. Because of the intramolecular charge transfer (ICT) effect and the turn-on sensing mode, the strong fluorometric emission towards Sn2+ was observed at about 435 nm. The chemosensor exhibited good selectivity for Sn2+ in the presence of coexisting metal ions. An improved linear connection was established with a low limit of detection (0.167 µM). FT-IR, 1H NMR, 13C NMR, and quantum chemistry methods were performed to verify the binding coordination mechanism. The chemosensing probe 2CAN-Dione was successfully employed in bioimaging investigations, demonstrating that it is a reliable fluorescent marker for Sn2+ in human cancer cells.

p21-activated kinase 4 suppresses fatty acid ß-oxidation and ketogenesis by phosphorylating NCoR1.

PPARα corepressor NCoR1 is a key regulator of fatty acid ß-oxidation and ketogenesis. However, its regulatory mechanism is largely unknown. Here, we report that oncoprotein p21-activated kinase 4 (PAK4) is an NCoR1 kinase. Specifically, PAK4 phosphorylates NCoR1 at T1619/T2124, resulting in an increase in its nuclear localization and interaction with PPARα, thereby repressing the transcriptional activity of PPARα. We observe impaired ketogenesis and increases in PAK4 protein and NCoR1 phosphorylation levels in liver tissues of high fat diet-fed mice, NAFLD patients, and hepatocellular carcinoma patients. Forced overexpression of PAK4 in mice represses ketogenesis and thereby increases hepatic fat accumulation, whereas genetic ablation or pharmacological inhibition of PAK4 exhibites an opposite phenotype. Interestingly, PAK4 protein levels are significantly suppressed by fasting, largely through either cAMP/PKA- or Sirt1-mediated ubiquitination and proteasome degradation. In this way, our findings provide evidence for a PAK4-NCoR1/PPARα signaling pathway that regulates fatty acid ß-oxidation and ketogenesis.

SIRT1 downregulation provokes immune-inflammatory responses in hair follicle outer root sheath cells and may contribute to development of alopecia areata.

BACKGROUND: Silent information regulator 1 (SIRT1), a type III histone deacetylase, is involved in various cutaneous and systemic autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, and psoriasis. However, little is known about the role of SIRT1 in the development of alopecia areata (AA). OBJECTIVES: This study investigated whether SIRT1 regulates the hair follicle immune system and is involved in AA pathogenesis. METHODS: SIRT1 expression in human scalp tissue was analyzed using immunohistochemical staining, qPCR, and western blotting. The regulatory effect of SIRT1 was evaluated after stimulation with the double-stranded RNA mimic polyinosinic:polycytidylic acid (poly I:C) in hair follicle outer root sheath (ORS) cells and C3H/HeJ mice. RESULTS: SIRT1 expression was significantly reduced in the AA scalp compared to the normal scalp. SIRT1 inhibition upregulated MHC class I polypeptide-related sequence A and UL16 binding protein 3 in hair follicle ORS cells. SIRT1 inhibition also promoted the production of Th1 cytokines (IFN-γ and TNF-α), IFN-inducible chemokines (CXCL9 and CXCL10), and T cell migration in ORS cells. Conversely, SIRT1 activation suppressed the autoreactive inflammatory responses. The counteractive effect of the immune response by SIRT1 was mediated through the deacetylation of NF-κB and phosphorylation of STAT3. CONCLUSION: SIRT1 downregulation induces immune-inflammatory responses in hair follicle ORS cells and may contribute to AA development.

3,3'-Diindolylmethane Augments 5-Fluorouracil-InducedGrowth Suppression in Gastric Cancer Cells through Suppression of the Akt/GSK-3ß and WNT/Beta-Catenin.

Gastric cancer (GC) is one of the most lethal cancers in South Korea, and it is a cancer of concern worldwide. 5-fluorouracil (5-Fu) is commonly used as the first-line therapy for advanced GC; however, its side effects often limit the dosage range and impair patients' quality of life. Due to the limitations of current chemotherapy, new anticancer therapies are urgently needed. 3,3'-diindolylmethane (DIM) has been reported to have the ability to protect against various types of cancer. Our study aimed to elucidate the anticancer effect of DIM in GC when treated with the chemotherapeutic agent 5-Fu. In our results, combined treatment with DIM and 5-Fu resulted in higher apoptosis and lower cell proliferation than treatment with 5-Fu in SNU484 and SNU638 cell lines. Furthermore, when DIM and 5-Fu were administered together, cell invasion was diminished by mediated E-cadherin, MMP-9, and uPA; p-Akt and p-GSK-3ß levels were reduced more significantly than when 5-Fu was administered alone. Moreover, in the Wnt signaling pathway, combined treatment of DIM and 5-Fu diminished ß-catenin levels in the nucleus and inhibited cyclin D1and c-Myc protein levels. The Akt inhibitor, wortmannin, further inhibited the levels of ß-catenin and c-Myc that were inhibited by DIM and 5-Fu. Furthermore, an animal xenograft model demonstrated that DIM combined with 5-Fu considerably reduced tumor growth without any toxic effects by regulating the Akt/GSK-3ß and ß-catenin levels. Our findings suggest that DIM significantly potentiates the anticancer effects of 5-Fu by targeting the Akt/GSK-3ß and WNT/ß-catenin because the combination therapy is more effective than 5-Fu alone, thereby offering an innovative potential therapy for patients with GC.

Inhibition of colorectal cancer tumorigenesis by ursolic acid and doxorubicin is mediated by targeting the Akt signaling pathway and activating the Hippo signaling pathway.

Colorectal cancer (CRC) is one of the deadliest malignant tumors worldwide and its prevalence is increasing in South Korea. The efficacy of combined treatment with natural product­derived and chemotherapy agents including curcumin combined with 5­fluorouracil, resveratrol combined with cisplatin and epigallocatechin­3­gallate (EGCG) combined with cisplatin in preventing cancer progression and killing cancer cells has emerged. The Akt and Hippo signaling pathways serve a key role in colorectal tumor growth; however, the exact role of the crosstalk between Akt and Hippo signaling pathways in CRC remains poorly elucidated. The combined effect of UA and DOX on the cell proliferation, apoptosis, migration and cell cycle of CRC cells were investigated by performing Cell proliferation assay, a soft agar colony formation assay, flow cytometry, wound healing assay and western blotting assay. Subsequently, the expression of AKT and Hippo signaling pathway­associated proteins were also assessed by western blot assay. Moreover, a xenograft nude mouse model was constructed to verify the effects of UA and DOX on the tumorigenesis of HCT116 cell in vivo. The present study reported that ursolic acid (UA) strongly enhanced the antitumor action of doxorubicin (DOX) via blocking the Akt/glycogen synthase kinase­3ß (Gsk3ß) signaling pathway and activating tumor­suppressive Hippo signaling (mammalian Ste20­like kinase 1 and 2, salvador family WW domain containing protein 1 and MOB kinase activator 1), thereby downregulating downstream effector yes­associated protein 1 (Yap) and connective tissue growth factor (CTGF) protein expression levels in CRC cells. Furthermore, The PI3K inhibitor LY294002 further suppressed Akt activity and enhance the function of Hippo pathway­associated proteins in DOX + UA treated cells; this effect led to subsequent oncogenic Yap and CTGF inhibition following combined treatment, whereas Akt activator SC79 exerted an opposite effect in CTGF expression. In vivo, treatment with UA combined with DOX markedly suppressed the progression of CRC without any toxic effects on a xenograft mouse model by disrupting Akt signaling and activating the Hippo signaling pathway. These results demonstrated that UA and DOX treatment successfully induced Akt/Gsk3ß inactivation via Hippo signaling pathway activation to promote Yap degradation, resulting in the inhibition of colorectal tumorigenesis. In conclusion, these findings suggested that combination therapy with UA and DOX may be more effective than DOX alone. UA may be a novel anticancer strategy and could be considered for investigation as a complementary chemotherapy agent in the future.

LDHA Desuccinylase Sirtuin 5 as A Novel Cancer Metastatic Stimulator in Aggressive Prostate Cancer.

Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men worldwide. Around 80% of the patients who developed advanced PCa suffered from bone metastasis, with a sharp drop in the survival rate. Despite great efforts, the detailed mechanisms underlying castration-resistant PCa (CRPC) remain unclear. Sirtuin 5 (SIRT5), an NAD+-dependent desuccinylase, is hypothesized to be a key regulator of various cancers. However, compared to other SIRTs, the role of SIRT5 in cancer has not been extensively studied. Here, we revealed significantly decreased SIRT5 levels in aggressive PCa cells relative to the PCa stages. The correlation between the decrease in the SIRT5 level and the patient's reduced survival rate was also confirmed. Using quantitative global succinylome analysis, we characterized a significant increase in the succinylation at lysine 118 (K118su) of lactate dehydrogenase A (LDHA), which plays a role in increasing LDH activity. As a substrate of SIRT5, LDHA-K118su significantly increased the migration and invasion of PCa cells and LDH activity in PCa patients. This study reveals the reduction of SIRT5 protein expression and LDHA-K118su as a novel mechanism involved in PCa progression, which could serve as a new target to prevent CPRC progression for PCa treatment.

SIRT1 Promotes Host Protective Immunity against Toxoplasma gondii by Controlling the FoxO-Autophagy Axis via the AMPK and PI3K/AKT Signalling Pathways.

Sirtuin 1 (SIRT1) regulates cellular processes by deacetylating non-histone targets, including transcription factors and intracellular signalling mediators; thus, its abnormal activation is closely linked to the pathophysiology of several diseases. However, its function in Toxoplasma gondii infection is unclear. We found that SIRT1 contributes to autophagy activation via the AMP-activated protein kinase (AMPK) and PI3K/AKT signalling pathways, promoting anti-Toxoplasma responses. Myeloid-specific Sirt1-/- mice exhibited an increased cyst burden in brain tissue compared to wild-type mice following infection with the avirulent ME49 strain. Consistently, the intracellular survival of T. gondii was markedly increased in Sirt1-deficient bone-marrow-derived macrophages (BMDMs). In contrast, the activation of SIRT1 by resveratrol resulted in not only the induction of autophagy but also a significantly increased anti-Toxoplasma effect. Notably, SIRT1 regulates the FoxO-autophagy axis in several human diseases. Importantly, the T. gondii-induced phosphorylation, acetylation, and cytosolic translocation of FoxO1 was enhanced in Sirt1-deficient BMDMs and the pharmacological inhibition of PI3K/AKT signalling reduced the cytosolic translocation of FoxO1 in BMDMs infected with T. gondii. Further, the CaMKK2-dependent AMPK signalling pathway is responsible for the effect of SIRT1 on the FoxO3a-autophagy axis and for its anti-Toxoplasma activity. Collectively, our findings reveal a previously unappreciated role for SIRT1 in Toxoplasma infection.

Targeting p21-activated kinase 4 (PAK4) with pyrazolo[3,4-d]pyrimidine derivative SPA7012 attenuates hepatic ischaemia-reperfusion injury in mice.

p21-Activated kinase 4 (PAK4), one of the serine/threonine kinases activated by Rho-family GTPases, has been widely studied as an oncogenic protein that is overexpressed in many types of cancers. In our recent study, PAK4 upregulation was observed in mice exhibiting hepatic ischaemia-reperfusion (I/R) and in liver transplantation patients. Liver I/R injury was also attenuated in Pak4 KO mice. Herein, we report a novel series of pyrazolo[3,4-d]pyrimidine derivatives of type I ½ PAK4 inhibitors. The most potent compound SPA7012 was evaluated to determine the pharmacological potential of PAK4 inhibitor in I/R injury in mice. Mice with I/R injury showed typical patterns of liver damage, as demonstrated by increases in serum levels of aminotransferases and proinflammatory cytokines, hepatocellular necrosis and apoptosis, and inflammatory cell infiltration, relative to sham mice. Conversely, intraperitoneal administration of SPA7012 dramatically attenuated biochemical and histopathologic changes. Mechanistically, stabilisation of nuclear factor-erythroid 2-related factor 2 (Nrf2), a master regulator of anti-oxidative response, was observed following SPA7012 treatment. SPA7012 treatment in primary hepatocytes also attenuated hypoxia-reoxygenation-induced apoptotic cell death and inflammation. Together, these results provide experimental evidence supporting the use of PAK4 inhibitors for alleviation of I/R-induced liver damage.

NAD+-boosting molecules suppress mast cell degranulation and anaphylactic responses in mice.

Nicotinamide adenine dinucleotide (NAD+) acts as a cofactor for multiple biological processes. While previous research has revealed that the NAD+ declines associated with aging contributes to an impairment of immune cells, its role in mast cell function, especially in response to an anaphylactic condition, has remained unexplored. We tested whether the restoration of cellular NAD+ concentration by the supplementation of NAD+ boosting molecules prevented mast cell degranulation and anaphylactic responses. Methods: Bone marrow derived mast cells (BMMCs) and human cord blood derived mast cells were treated with NAD+ precursors nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), and FcεRI downstream signaling was assessed. Animal models of passive systemic anaphylaxis (PSA) and passive cutaneous anaphylaxis (PCA) were used to investigate the effects of NAD+ precursors in the anaphylactic responses of mice. Results: Treatment of murine BMMCs and human cord blood derived mast cells with NAD+ precursors repressed intracellular signaling downstream of FcεRI, as well as the release of inflammatory cytokines and lipid mediators. The intraperitoneal administration of NMN or NR also markedly attenuated IgE-mediated anaphylactic responses in mouse models of PSA and PCA. These beneficial effects of NAD+ precursors, however, were attenuated in mast cell-specific Sirt6 knockout mice, indicating a Sirt6 dependency for their action. Conclusion: NAD+ precursors may serve as an effective therapeutic strategy that limits mast cell-mediated anaphylactic responses.

Loss of Proximal Tubular Sirtuin 6 Aggravates Unilateral Ureteral Obstruction-Induced Tubulointerstitial Inflammation and Fibrosis by Regulation of ß-Catenin Acetylation.

Renal fibrosis is a significant pathologic change associated with progressive kidney disease. Sirt6 is an NAD+-dependent deacetylase and mono-ADP ribosyltransferase known to play diverse roles in the processes attendant to aging, metabolism, and carcinogenesis. However, the role of proximal tubule-specific Sirt6 in renal fibrosis remains elusive. This study investigates the effect of proximal tubule-specific Sirt6 knockdown on unilateral ureteral obstruction (UUO)-induced renal tubulointerstitial inflammation and fibrosis. Renal fibrosis in wild type and PT-Sirt6KO (Sirt6flox/flox; Ggt1-Cre+) mice was induced by UUO surgery. After seven days, histologic examination and Western blot analysis were performed to examine extracellular matrix (ECM) protein expression. We evaluated inflammatory cytokine and cell adhesion molecule expression after ureteral obstruction. The therapeutic effect of Sirt6 activator MDL-800 on UUO-induced tubulointerstitial inflammation and fibrosis was assessed. The loss of Sirt6 in the proximal tubules aggravated UUO-induced tubular injury, ECM deposition, F4/80 positive macrophage infiltration, and proinflammatory cytokine and chemokine expression. Sirt6 activator MDL-800 mitigated UUO-induced renal tubulointerstitial inflammation and fibrosis. In an in vitro experiment, MDL-800 decreases the transforming growth factor (TGF)-ß1-induced activation of myofibroblast and ECM production by regulating Sirt6-dependent ß-catenin acetylation and the TGF-ß1/Smad signaling pathway. In conclusion, proximal tubule Sirt6 may play an essential role in UUO-induced tubulointerstitial inflammation and fibrosis by regulating Sirt6-dependent ß-catenin acetylation and ECM protein promoter transcription.

p21-activated kinase 4 inhibition protects against liver ischemia/reperfusion injury: Role of nuclear factor erythroid 2-related factor 2 phosphorylation.

BACKGROUND AND AIMS: p21-activated kinase 4 (PAK4), an oncogenic protein, has emerged as a promising target for anticancer drug development. Its role in oxidative stress conditions, however, remains elusive. We investigated the effects of PAK4 signaling on hepatic ischemia/reperfusion (I/R) injury. APPROACH AND RESULTS: Hepatocyte- and myeloid-specific Pak4 knockout (KO) mice and their littermate controls were subjected to a partial hepatic I/R (HIR) injury. We manipulated the catalytic activity of PAK4, either through genetic engineering (gene knockout, overexpression of wild-type [WT] or dominant-negative kinase) or pharmacological inhibitor, coupled with a readout of nuclear factor erythroid 2-related factor 2 (Nrf2) activity, to test the potential function of PAK4 on HIR injury. PAK4 expression was markedly up-regulated in liver during HIR injury in mice and humans. Deletion of PAK4 in hepatocytes, but not in myeloid cells, ameliorated liver damages, as demonstrated in the decrease in hepatocellular necrosis and inflammatory responses. Conversely, the forced expression of WT PAK4 aggravated the pathological changes. PAK4 directly phosphorylated Nrf2 at T369, and it led to its nuclear export and proteasomal degradation, all of which impaired antioxidant responses in hepatocytes. Nrf2 silencing in liver abolished the protective effects of PAK4 deficiency. A PAK4 inhibitor protected mice from HIR injury. CONCLUSIONS: PAK4 phosphorylates Nrf2 and suppresses its transcriptional activity. Genetic or pharmacological suppression of PAK4 alleviates HIR injury. Thus, PAK4 inhibition may represent a promising intervention against I/R-induced liver injury.

SIRT5 Directly Inhibits the PI3K/AKT Pathway in Prostate Cancer Cell Lines.

BACKGROUND/AIM: Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men globally. Among patients who develop advanced PCa, 80% are affected by bone metastasis, with a sharp drop in survival rate. Despite efforts, the details of mechanisms of metastasis of PCa remain unclear. SIRT5, an NAD+-dependent deacylase, is hypothesized to be a crucial regulator of various cancers. The role of SIRT5 in cancer has not been extensively studied compared to other SIRTs. In this study, we showed significantly decreased levels of SIRT5 in PC-3M, a highly aggressive PC-3 cell variant. MATERIALS AND METHODS: We characterized the differentially expressed proteins between parental and SIRT5 KO PC-3 cells using quantitative proteomics analysis. RESULTS: A significant increase in expression of interleukin-1ß (IL-1ß) in SIRT5 KO cells was observed, and the PI3K/AKT/NF-ĸB signaling pathway was found significantly elevated in SIRT5 KO cells by the Gene Ontology annotation and KEGG pathway functional enrichment analysis. Moreover, we confirmed that SIRT5 can bind PI3K by immunoprecipitation analysis. CONCLUSION: This study is the first to demonstrate a relationship between SIRT5 and PCa metastasis, suggesting that SIRT5-mediated inhibition of the PI3K/AKT/NK-kB pathway is reduced for secondary metastasis from bone to other tissues.

Sirtuin 6 is a negative regulator of FcεRI signaling and anaphylactic responses.

BACKGROUND: Binding IgE to a cognate allergen causes aggregation of Fcε receptor I (FcεRI) in mast cells, resulting in activation of receptor-associated Src family tyrosine kinases, including Lyn and Syk. Protein tyrosine phosphatase, receptor type C (PTPRC), also known as CD45, has emerged as a positive regulator of FcεRI signaling by dephosphorylation of the inhibitory tyrosine of Lyn. OBJECTIVE: Sirtuin 6 (Sirt6), a NAD+-dependent deacetylase, exhibits an anti-inflammatory property. It remains to be determined, however, whether Sirt6 attenuates mast cell-associated diseases, including anaphylaxis. METHODS: FcεRI signaling and mast cell degranulation were measured after IgE cross-linking in murine bone marrow-derived mast cells (BMMCs) and human cord blood-derived mast cells. To investigate the function of Sirt6 in mast cell activation in vivo, we used mast cell-dependent animal models of passive systemic anaphylaxis (PSA) and passive cutaneous anaphylaxis (PCA). RESULTS: Sirt6-deficient BMMCs augmented IgE-FcεRI-mediated signaling and degranulation compared to wild-type BMMCs. Reconstitution of mast cell-deficient KitW-sh/W-sh mice with BMMCs received from Sirt6 knockout mice developed more severe PSA and PCA compared to mice engrafted with wild-type BMMCs. Similarly, genetic overexpression or pharmacologic activation of Sirt6 suppressed mast cell degranulation and blunted responses to PCA. Mechanistically, Sirt6 deficiency increased PTPRC transcription via acetylating histone H3, leading to enhanced aggregation of FcεRI in BMMCs. Finally, we recapitulated the Sirt6 regulation of PTPRC and FcεRI signaling in human mast cells. CONCLUSIONS: Sirt6 acts as a negative regulator of FcεRI signaling cascade in mast cells by suppressing PTPRC transcription. Activation of Sirt6 may therefore represent a promising and novel therapeutic strategy for anaphylaxis.

Ursolic Acid Accelerates Paclitaxel-Induced Cell Death in Esophageal Cancer Cells by Suppressing Akt/FOXM1 Signaling Cascade.

Ursolic acid (UA), a pentacyclic triterpenoid extracted from various plants, inhibits cell growth, metastasis, and tumorigenesis in various cancers. Chemotherapy resistance and the side effects of paclitaxel (PTX), a traditional chemotherapy reagent, have limited the curative effect of PTX in esophageal cancer. In this study, we investigate whether UA promotes the anti-tumor effect of PTX and explore the underlying mechanism of their combined effect in esophageal squamous cell carcinoma (ESCC). Combination treatment with UA and PTX inhibited cell proliferation and cell growth more effectively than either treatment alone by inducing more significant apoptosis, as indicated by increased sub-G1 phase distribution and protein levels of cleaved-PARP and cleaved caspase-9. Similar to the cell growth suppressive effect, the combination of UA and PTX significantly inhibited cell migration by targeting uPA, MMP-9, and E-cadherin in ESCC cells. In addition, combination treatment with UA and PTX significantly activated p-GSK-3ß and suppressed the activation of Akt and FOXM1 in ESCC cells. Those effects were enhanced by the Akt inhibitor LY2940002 and inverted by the Akt agonist SC79. In an in vivo evaluation of a murine xenograft model of esophageal cancer, combination treatment with UA and PTX suppressed tumor growth significantly better than UA or PTX treatment alone. Thus, UA effectively potentiates the anti-tumor efficacy of PTX by targeting the Akt/FOXM1 cascade since combination treatment shows significantly more anti-tumor potential than PTX alone both in vitro and in vivo. Combination treatment with UA and PTX could be a new strategy for curing esophageal cancer patients.

p21-activated kinase 4 phosphorylates peroxisome proliferator-activated receptor Υ and suppresses skeletal muscle regeneration.

BACKGROUND: Skeletal muscle regeneration is an adaptive response to injury that is crucial to the maintenance of muscle mass and function. A p21-activated kinase 4 (PAK4) serine/threonine kinase is critical to the regulation of cytoskeletal changes, cell proliferation, and growth. However, PAK4's role in myoblast differentiation and regenerative myogenesis remains to be determined. METHODS: We used a mouse model of myotoxin (notexin)-induced muscle regeneration. In vitro myogenesis was performed in the C2C12 myoblast cell line, primary myoblasts, and primary satellite cells. In vivo overexpression of PAK4 or kinase-inactive mutant PAK4S474A was conducted in skeletal muscle to examine PAK4's kinase-dependent effect on muscle regeneration. The regeneration process was evaluated by determining the number and size of multinucleated myofibres and expression patterns of myogenin and eMyHC. To explore whether PAK4 inhibition improves muscle regeneration, mice were injected intramuscularly with siRNA that targeted PAK4 or orally administered with a chemical inhibitor of PAK4. RESULTS: p21-activated kinase 4 was highly expressed during the myoblast stage, but expression gradually and substantially decreased as myoblasts differentiated into myotubes. PAK4 overexpression, but not kinase-inactive mutant PAK4S474A overexpression, significantly impeded myoblast fusion and MyHC-positive myotube formation in C2C12 cells, primary myoblasts, and satellite cells (P < 0.01). Conversely, PAK4 silencing led to an 8.7% and a 20.3% increase in the number of multinucleated larger myotubes in C2C12 cells and primary myoblasts. Further, in vivo overexpression of PAK4 by adenovirus injection to mice prior to and after myotoxin-induced injury led to a 52.6% decrease in the number of eMyHC-positive myofibres on Day 5 in tibialis anterior muscles as compared with those injected with control adenoviruses (P < 0.01), while Ad-PAK4S474A showed comparable muscle regeneration parameters. PAK4-induced repression of muscle regeneration coincided with an increase in phosphatase and tensin homologue (PTEN) expression and a decrease in phosphoinositide 3-kinase-Akt signalling. In contrast, PAK4 silencing reduced PTEN expression in mice. Consistent with these findings, prodrug of PAK4 inhibitor CZh-226 (30 mg/kg) orally administered to mice repressed PTEN expression and accelerated myotube formation. Subsequent mechanistic studies revealed that PAK4 directly phosphorylates PPARγ at S273 to increase its transcription activity, thereby up-regulating PTEN expression. Importantly, an analysis of the Genotype-Tissue Expression database showed a positive correlation between PAK4 and PTEN in human skeletal muscle tissues (P < 0.01). CONCLUSIONS: p1-activated kinase 4 is a new member of PPARγ kinase, and PAK4 inhibition may have a therapeutic role as an accelerant of muscle regeneration.

Repurposing the anthelmintic praziquantel to treat psoriasis.

BACKGROUND AND PURPOSE: The anthelmintic drug praziquantel has been used as a standard treatment for schistosomiasis for over 40 years. This study aimed to repurpose praziquantel to treat psoriasis. EXPERIMENTAL APPROACH: Psoriasis-like skin inflammation was induced in mice (C57 and Balb/C) by topical application of imiquimod or intradermal injection of recombinant IL-23. Praziquantel was either orally or topically administered during the psoriasis induction period. KEY RESULTS: Mice treated with either oral or topical praziquantel exhibited markedly improved psoriasiform skin symptoms when compared with control mice, as judged by disease severity score, epidermal thickening, inflammatory cell infiltration and spleen size. Flow cytometric analysis of infiltrating immune cells from mouse skin displayed reduced infiltration of Th17 cells. In vitro experiments revealed that praziquantel inhibited STAT3 phosphorylation and RORγt expression in splenic CD4+ T-cells. Praziquantel also decreased STAT3 phosphorylation in HEK-A/F cells. Down-regulation of STAT3 phosphorylation in these cells accounts for the decreased number of Th17 cells and keratinocytes. CONCLUSION AND IMPLICATIONS: These results provide the first preclinical evidence that praziquantel may effectively treat psoriasis, and suggest that praziquantel alleviates symptoms in mice by inhibiting STAT3 phosphorylation, thereby suppressing Th17 immune responses.

Mitochondria-targeted acridine-based dual-channel fluorescence chemosensor for detection of Sn4+ and Cr2O72- ions in water and its application in discriminative detection of cancer cells.

The goal of the present work was to fabricate a new low-cost, easy-to-prepare, dual-channel fluorescence chemosensor comprised of acridine-diphenylacetyl moieties (NDA) to enable remarkable Sn4+ detection in water and biological medium. The resulting NDA-Sn4+ complex was utilized for the distinguished identification of Cr2O72- ions from other anions and biomolecules. These investigations involve the absorption, fluorescence, and electrochemical methods for the detection of Sn4+ and Cr2O72- ions in pure water. The mechanism for NDA-mediated Sn4+ detection was experimentally determined by FT-IR, NMR titrations, mass (ESI) analyses, and DFT calculations. The obtained results indicate that the NDA chemosensor possessed excellent performance characteristics including good water solubility and compatibility, quick response time (less than 10 s), high sensitivity (Sn4+ = 0.268 µM and Cr2O72- = 0.160 µM), and selectivity against coexisting metals, anions, amino acids, and peptides. The chemosensor NDA induced negligible toxicity in live cells and was successfully utilized as a biomarker for the tracking of Sn4+ in human normal and cancer cells. More importantly, NDA demonstrates distinguished recognition of Sn4+ in human cancer cells rather than in normal live cells. Additionally, NDA was shown to act as a mitochondria-targeted probe in FaDu cells.

Inactivation of the Akt/FOXM1 Signaling Pathway by Panobinostat Suppresses the Proliferation and Metastasis of Gastric Cancer Cells.

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. Histone deacetylase (HDAC) inhibitors are a new class of cytostatic agents available for the treatment of various cancers and diseases. Although numerous clinical and pre-clinical trials on the anticancer effects of panobinostat have been conducted, only a few reports have investigated its efficacy in gastric cancer. The present study aimed to investigate the effects of panobinostat in gastric cancer cells. Panobinostat significantly inhibited the cell viability and proliferation of the gastric cancer cell lines SNU484 and SNU638 in a dose-dependent manner; it reduced the colony-forming ability of these cells. Moreover, it induced apoptosis as indicated by increased protein levels of cleaved poly ADP-ribose polymerase and cleaved caspase-3. Panobinostat induced the G2/M cell cycle arrest in SNU484 and SNU638 cells and subsequently decreased the G2/M phase regulatory-associated protein expression of p-Wee1, Myt1, and Cdc2. Furthermore, panobinostat significantly inhibited the metastasis of SNU484 and SNU638 cells by regulating the expression of MMP-9 and E-cadherin. Further, it decreased the protein levels of p-Akt and forkhead box protein M1 (FOXM1). These effects were reversed by the Akt agonist SC79 and were accelerated by the Akt inhibitor LY2940002. Moreover, tumor growth in xenograft animal experiments was suppressed by panobinostat. These results indicated that panobinostat inhibits the proliferation, metastasis, and cell cycle progression of gastric cancer cells by promoting apoptosis and inactivating Akt/FOXM1 signaling. Cumulatively, our present study suggests that panobinostat is a potential drug for the treatment of gastric cancer.

Regulation of Alcohol and Acetaldehyde Metabolism by a Mixture of Lactobacillus and Bifidobacterium Species in Human.

Excessive alcohol consumption is one of the most significant causes of morbidity and mortality worldwide. Alcohol is oxidized to toxic and carcinogenic acetaldehyde by alcohol dehydrogenase (ADH) and further oxidized to a non-toxic acetate by aldehyde dehydrogenase (ALDH). There are two major ALDH isoforms, cytosolic and mitochondrial, encoded by ALDH1 and ALDH2 genes, respectively. The ALDH2 polymorphism is associated with flushing response to alcohol use. Emerging evidence shows that Lactobacillus and Bifidobacterium species encode alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) mediate alcohol and acetaldehyde metabolism, respectively. A randomized, double-blind, placebo-controlled crossover clinical trial was designed to study the effects of Lactobacillus and Bifidobacterium probiotic mixture in humans and assessed their effects on alcohol and acetaldehyde metabolism. Here, twenty-seven wild types (ALDH2*1/*1) and the same number of heterozygotes (ALDH2*2/*1) were recruited for the study. The enrolled participants were randomly divided into either the probiotic (Duolac ProAP4) or the placebo group. Each group received a probiotic or placebo capsule for 15 days with subsequent crossover. Primary outcomes were measurement of alcohol and acetaldehyde in the blood after the alcohol intake. Blood levels of alcohol and acetaldehyde were significantly downregulated by probiotic supplementation in subjects with ALDH2*2/*1 genotype, but not in those with ALDH2*1/*1 genotype. However, there were no marked improvements in hangover score parameters between test and placebo groups. No clinically significant changes were observed in safety parameters. These results suggest that Duolac ProAP4 has a potential to downregulate the alcohol and acetaldehyde concentrations, and their effects depend on the presence or absence of polymorphism on the ALDH2 gene.