野黄芩苷通过hedgehog信号通路抑制结肠肿瘤干细胞分化的研究

该文旨在研究野黄芩苷对结肠肿瘤干细胞体外和体内分化的影响,揭示野黄芩苷基于hedgehog信号通路的抑制结肠肿瘤干细胞分化的作用机制。用3D细胞培养法观察野黄芩苷对结肠肿瘤干细胞HT-29CSC体外生长的影响;用软琼脂克隆形成实验研究野黄芩苷对HT-29CSC细胞转化的影响;用胎牛血清诱导干细胞分化实验,研究野黄芩苷对HT-29CSC细胞体外分化的影响;用qRT-PCR法检测野黄芩苷对HT-29CSC细胞中Lgr5,c-Myc,CK20和Nanog mRNA表达的影响;用Western blot法检测野黄芩苷对HT-29CSC细胞中c-Myc,Gli1,Lgr5蛋白表达的影响。通过裸鼠皮下接种HT-29CSC细胞建立肿瘤干细胞体内分化成瘤模型,研究野黄芩苷对裸鼠体质量和HT-29CSC细胞分化成瘤的影响;用qRT-PCR法检测肿瘤组织中CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki-67,CK20,Nanog mRNA表达水平;用Western blot法及免疫组织化学法检测肿瘤组织中c-Myc,Gli1,Lgr5,CD133,Ki-67蛋白表达水平。体外研究表明,野黄芩苷能够抑制HT-29CSC细胞生长、转化与分化,同时显著下调HT-29CSC细胞中Lgr5,c-Myc,CK20,Nanog mRNA水平和c-Myc,Gli1,Lgr5蛋白表达。动物实验表明,野黄芩苷显著抑制裸鼠皮下HT-29CSC细胞分化成瘤,并且下调肿瘤组织中CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki-67,CK20,Nanog mRNA表达和c-Myc,Gli1,Lgr5,CD133,Ki-67蛋白表达。综上所述,野黄芩苷能够抑制结肠肿瘤干细胞的体外和体内分化,其作用机制在于下调hedgehog信号通路活性。     

TGF-β/Smad signaling through DOCK4 facilitates lung adenocarcinoma metastasis

The mechanisms by which TGF-β promotes lung adenocarcinoma (ADC) metastasis are largely unknown. Here, we report that in lung ADC cells, TGF-β potently induces expression of DOCK4, but not other DOCK family members, via the Smad pathway and that DOCK4 induction mediates TGF-β’s prometastatic effects by enhancing tumor cell extravasation. TGF-β-induced DOCK4 stimulates lung ADC cell protrusion, motility, and invasion without affecting epithelial-to-mesenchymal transition. These processes, which are fundamental to tumor cell extravasation, are driven by DOCK4-mediated Rac1 activation, unveiling a novel link between TGF-β and Rac1. Thus, our findings uncover the atypical Rac1 activator DOCK4 as a key component of the TGF-β/Smad pathway that promotes lung ADC cell extravasation and metastasis.     

Melatonin ameliorates amyloid beta‐induced memory deficits,tau hyperphosphorylation and neurodegeneration via PI3/Akt/GSk3β pathway in the mouse hippocampus

Alzheimer's disease (AD) is the most prevalent age‐related neurodegenerative disease, pathologically characterized by the accumulation of amyloid beta (Aβ) aggregation in the brain, and is considered to be the primary cause of cognitive dysfunction. Aβ aggregates lead to synaptic disorder, tau hyperphosphorylation, and neurodegeneration. In this study, the underlying neuroprotective mechanism of melatonin against Aβ_1‐42‐induced neurotoxicity was investigated in the mice hippocampus. Intracerebroventricular (i.c.v.) Aβ_1‐42‐injection triggered memory impairment, synaptic disorder, hyperphosphorylation of tau protein, and neurodegeneration in the mice hippocampus. After 24 hr of Aβ_1‐42 injection, the mice were treated with melatonin (10 mg/kg, intraperitonially) for 3 wks, reversed the Aβ_1‐42‐induced synaptic disorder via increasing the level of presyanptic (Synaptophysin and SNAP‐25) and postsynaptic protein [PSD95, p‐GluR1 (Ser845), SNAP23, and p‐CREB (Ser133)], respectively, and attenuated the Aβ_1‐42‐induced memory impairment. Chronic melatonin treatment attenuated the hyperphosphorylation of tau protein via PI3K/Akt/GSK3β signaling by activating the p‐PI3K, p‐Akt (Ser 473) and p‐GSK3β (Ser9) in the Aβ_1‐42‐treated mice. Furthermore, melatonin decreased Aβ_1‐42‐induced apoptosis through decreasing the overexpression of caspase‐9, caspase‐3, and PARP‐1 level. Additionally, the evaluation of immunohistochemical analysis of caspase‐3, Fluorojade‐B, and Nissl staining indicated that melatonin prevented neurodegeneration in Aβ_1‐42‐treated mice. Our results demonstrated that melatonin has neuroprotective effect against Aβ_1‐42‐induced neurotoxicity through decreasing memory impairment, synaptic disorder, tau hyperphosphorylation, and neurodegeneration via PI3K/Akt/GSK3β signaling in the Aβ_1‐42‐treated mouse model of AD. On the basis of these results, we suggest that melatonin could be an effective, promising, and safe neuroprotective candidate for the treatment of progressive neurodegenerative disorders, such as AD.     

Melatonin prevents cell death and mitochondrial dysfunction via a SIRT1‐dependent mechanism during ischemic‐stroke in mice

Silent information regulator 1 (SIRT1), a type of histone deacetylase, is a highly effective therapeutic target for protection against ischemia reperfusion (IR) injury (IRI). Previous studies showed that melatonin preserves SIRT1 expression in neuronal cells of newborn rats after hypoxia–ischemia. However, the definite role of SIRT1 in the protective effect of melatonin against cerebral IRI in adult has not been explored. In this study, the brain of adult mice was subjected to IRI. Prior to this procedure, the mice were given intraperitoneal with or without the SIRT1 inhibitor, EX527. Melatonin conferred a cerebral‐protective effect, as shown by reduced infarct volume, lowered brain edema, and increased neurological scores. The melatonin‐induced upregulation of SIRT1 was also associated with an increase in the anti‐apoptotic factor, Bcl2, and a reduction in the pro‐apoptotic factor Bax. Moreover, melatonin resulted in a well‐preserved mitochondrial membrane potential, mitochondrial Complex I activity, and mitochondrial cytochrome c level while it reduced cytosolic cytochrome c level. However, the melatonin‐elevated mitochondrial function was reversed by EX527 treatment. In summary, our results demonstrate that melatonin treatment attenuates cerebral IRI by reducing IR‐induced mitochondrial dysfunction through the activation of SIRT1 signaling.     

Is the autophagy a friend or foe in the silver nanoparticles associated radiotherapy for glioma？

Malignant glioma is the most common intracranial tumor with a dismal prognosis. The radiosensitizing effect of silver nanoparticles (AgNPs) on glioma both in vitro and in vivo had been demonstrated in the previous studies of our group. However, the underlying mechanism is still unclear. Consistent with previous studies, a size and dose dependent antitumor effect and significant radiosensitivity enhancing effect of AgNPs were observed in our experiment system. We also found that cell protective autophagy could be induced by AgNPs and/or radiation, which was verified by the use of 3-MA. The mechanism through which had autophagy and the enhancement of radiosensitivity taken place was further investigated with inhibitors of ERK and JNK pathways. We demonstrated that ERK and JNK played pivotal roles in the radiosensitivity enhancement. Inhibiting ERK and JNK with U0126 and SP600125 respectively, we found that the autophagy level of the cells treated with AgNPs and radiation were attenuated. Moreover, SP600125 down-regulated the apoptosis rate of the co-treated cells significantly. Taken together, the present study would have important impact on biomedical applications of AgNPs and clinical treatment for glioma.     

Melatonin alleviates brain injury in mice subjected to cecal ligation and puncture via attenuating inflammation,apoptosis, and oxidative stress: the role of SIRT1 signaling

Sepsis is a systemic inflammatory response to infection that causes severe neurological complications. Previous studies have suggested that melatonin is protective during sepsis. Additionally, silent information regulator 1 (SIRT1) was reported to be beneficial in sepsis. However, the role of SIRT1 signaling in the protective effect of melatonin against septic encephalopathy remains unclear. This study aimed to investigate the role of SIRT1 in the protective effect of melatonin. EX527, a SIRT1 inhibitor, was used to reveal the role of SIRT1 in melatonin's action. Cecal ligation and puncture or sham operation was performed in male C57BL/6J mice. Melatonin was administrated intraperitoneally (30 mg/kg). The survival rate of mice was recorded for the 7‐day period following the sham or CLP operation. The blood–brain barrier (BBB) integrity, brain water content, levels of inflammatory cytokines (TNF‐α, IL‐1β, and HMGB1), and the level of oxidative stress (superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA)) and apoptosis were assessed. The expression of SIRT1, Ac‐FoxO1, Ac‐p53, Ac‐NF‐κB, Bcl‐2, and Bax was detected by Western blot. The results suggested that melatonin improved survival rate, attenuated brain edema and neuronal apoptosis, and preserved BBB integrity. Melatonin decreased the production of TNF‐α, IL‐1β, and HMGB1. Melatonin increased the activity of SOD and CAT and decreased the MDA production. Additionally, melatonin upregulated the expression of SIRT1 and Bcl‐2 and downregulated the expression of Ac‐FoxO1, Ac‐p53, Ac‐NF‐κB, and Bax. However, the protective effects of melatonin were abolished by EX527. In conclusion, our results demonstrate that melatonin attenuates sepsis‐induced brain injury via SIRT1 signaling activation.     

Wnt/β⁃catenin信号通路参与马蹄内翻足畸形形成的研究

目的　探讨Sox9（sex determining region Y-box9）和β-catenin对先天性马蹄内翻足（congenital talipes equinovarus，CTE）的影响以及Wnt/β-catenin信号通路作用机制。 方法　将孕10 d的SD大鼠随机均分为实验组及对照组，以135 mg/kg全反式维甲酸溶于矿物油对实验组大鼠进行灌胃制作胎鼠CTE模型，对照组予以等量矿物油灌胃处理，取大鼠足踝部组织，通过免疫组化、RT-PCR、Western blot检测β-catenin、Sox9以及磷酸化β-catenin-S552的表达水平。 结果　与对照组相比，HE染色可见CTE模型组织中有较多的胶原组织沉积，免疫组化结果显示实验组标本Sox9与β-catenin表达增高，RT-qPCR表明实验组Sox9与β-catenin的mRNA水平显著增高，Western blot结果显示实验组Sox9与β-catenin的表达增高而磷酸化β-catenin-S552表达降低。 结论　CTE大鼠的足踝部组织中Sox9高表达受Wnt/β-catenin信号通路调控，该通路参与先天性马蹄内翻足畸形的形成。     

寻常痤疮发病机制相关信号通路的研究进展

寻常痤疮是一种毛囊皮脂腺单位的炎症疾病,在青少年中的发病率高达85%,发病机制与雄激素、皮脂分泌、嗜脂性微生物感染、免疫-炎症反应等密切相关。本文从炎症信号通路、皮脂分泌通路方面,综述与痤疮相关的信号转导通路。