NEAT1通过PI3K/AKT/Bcl-2信号通路抑制骨质疏松

为探讨NEAT1在骨质疏松症中的作用以及可能的病理机制,本研究通过建立卵巢去势和鼠尾悬挂2种骨质疏松的小鼠模型,将C57BL/6分为假手术组(Sham组)、OVX组和TS组;经过PCR测定小鼠NEAT1的表达;Elisa法检测小鼠E2、ALP和TRACP水平;Western blotting检测细胞凋亡因子PI3K/AKT/Bcl-2的蛋白水平。结果显示,建模4周后,3组小鼠体重没有显著变化;与Sham组相比,OVX组和TS组小鼠的骨密度值显著降低,骨生化指标ALP和TRACR水平明显升高;OVX组小鼠的E2水平与Sham组相比明显降低;与Sham组相比,OVX组和TS组小鼠的NEAT1表达显著下调;与Sham组相比,OVX组和TS组小鼠p-AKT和Bcl-2蛋白水平明显降低。本研究结果表明,NEAT1可能通过抑制PI3K/AKT/Bcl-2细胞凋亡途径诱导骨质疏松。     

Silencing of Receptor Tyrosine Kinase ROR1 Inhibits Tumor-Cell Proliferation via PI3K/AKT/mTOR Signaling Pathway in Lung Adenocarcinoma

Receptor tyrosine kinase ROR1, an embryonic protein involved in organogenesis, is expressed in certain hematological malignancies and solid tumors, but is generally absent in adult tissues. This makes the protein an ideal drug target for cancer therapy. In order to assess the suitability of ROR1 as a cell surface antigen for targeted therapy of lung adenocarcinoma, we carried out a comprehensive analysis of ROR1 protein expression in human lung adenocarcinoma tissues and cell lines. Our data show that ROR1 protein is selectively expressed on lung adenocarcinoma cells, but do not support the hypothesis that expression levels of ROR1 are associated with aggressive disease. However silencing of ROR1 via siRNA treatment significantly down-regulates the activity of the PI3K/AKT/mTOR signaling pathway. This is associated with significant apoptosis and anti-proliferation of tumor cells. We found ROR1 protein expressed in lung adenocarcinoma but almost absent in tumor-adjacent tissues of the patients. The finding of ROR1-mediated proliferation signals in both tyrosine kinase inhibitor (TKI)-sensitive and -resistant tumor cells provides encouragement to develop ROR1-directed targeted therapy in lung adenocarcinoma, especially those with TKI resistance.     

Beauvericin Ameliorates Experimental Colitis by Inhibiting Activated T Cells via Downregulation of the PI3K/Akt Signaling Pathway

Crohn''s disease is a common, chronic inflammatory bowel condition characterized by remission and relapse. Accumulating evidence indicates that activated T cells play an important role in this disease. In the present study, we aimed to examine the effect of beauvericin, a natural cyclic peptide, on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice, which mimics Crohn''s disease. Beauvericin significantly reduced weight loss, diarrhea and mortality, accompanied with notable alleviation of macroscopic and microscopic signs. In addition, this compound decreased serum levels of tumor necrosis factor (TNF)-α and interferon (IFN)- γ in a concentration-dependent manner in mice with experimental colitis. These effects of beauvericin are attributed to its inhibition on activated T cells. Flow cytometry and immunoblot assay data showed that beauvericin suppressed T-cell proliferation, activation and IFN-γ-STAT1-T-bet signaling and subsequently led to apoptosis of activated T cells by suppressing Bcl-2 and phosphorylated Bad as well as increasing cleavage of caspase-3, -9, -12 and PARP. Furthermore, inhibition of PI3K/Akt signaling, which was an upstream regulator of cell activation and survival in activated T cells, contributed to the effect of beauvericin. Overall, these results supported beauvericin as a novel drug candidate for the treatment of colonic inflammation mainly by targeting PI3K/Akt in activated T cells.     

Hantaan Virus Nucleocapsid Protein Binds to Importin α Proteins and Inhibits Tumor Necrosis Factor Alpha-Induced Activation of Nuclear Factor Kappa B

Hantaviruses such as Hantaan virus (HTNV) and Andes virus cause two human diseases, hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome, respectively. For both, disease pathogenesis is thought to be immunologically mediated and there have been numerous reports of patients with elevated levels of proinflammatory and inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), in their sera. Multiple viruses have developed evasion strategies to circumvent the host cell inflammatory process, with one of the most prevalent being the disruption of nuclear factor kappa B (NF-κB) activation. We hypothesized that hantaviruses might also moderate host inflammation by interfering with this pathway. We report here that the nucleocapsid (N) protein of HTNV was able to inhibit TNF-α-induced activation of NF-κB, as measured by a reporter assay, and the activation of endogenous p65, an NF-κB subunit. Surprisingly, there was no defect in the degradation of the inhibitor of NF-κB (IκB) protein, nor was there any alteration in the level of p65 expression in HTNV N-expressing cells. However, immunofluorescence antibody staining demonstrated that cells expressing HTNV N protein and a green fluorescent protein-p65 fusion had limited p65 nuclear translocation. Furthermore, we were able to detect an interaction between HTNV N protein and importin α, a nuclear import molecule responsible for shuttling NF-κB to the nucleus. Collectively, our data suggest that HTNV N protein can sequester NF-κB in the cytoplasm, thus inhibiting NF-κB activity. These findings, which were obtained using cells transfected with cDNA representing the HTNV N gene, were confirmed using HTNV-infected cells.     

Arctigenin,a Natural Lignan Compound,Induces Apoptotic Death of Hepatocellular Carcinoma Cells via Suppression of PI3‐K/Akt Signaling

In this study, we explored the cytotoxic effects of arctigenin, a natural lignan compound, on human hepatocellular carcinoma (HCC) cells and check the involvement of phosphatidylinositol 3‐kinase (PI3‐K)/Akt signaling. HCC cells were treated with different concentrations of arctigenin and cell viability and apoptosis were assessed. Manipulating Akt signaling was used to determine its role in the action of arctigenin. Arctigenin significantly inhibited the viability of HCC cells in a concentration‐dependent manner. Arctigenin induced apoptosis and activation of caspase‐9 and ‐3. Overexpression of a constitutively active Akt mutant blocked arctigenin‐induced apoptosis. Combinational treatment with arctigenin and the PI3‐K inhibitor LY294002 significantly enhanced apoptosis. Arctigenin reduced the expression of Bcl‐xL, Mcl‐1, and survivin and the phosphorylation of mTOR and S6K, which were significantly reversed by overexpression of constitutively active Akt. This is the first report about the anticancer activity of arctigenin in HCC cells, which is mediated by inactivation of PI3‐K/Akt signaling.     

The Tumor Suppressor SCRIB is a Negative Modulator of the Wnt/β‐Catenin Signaling Pathway

SCRIB is a scaffold protein containing leucine‐rich repeats (LRR) and PSD‐95/Dlg‐A/ZO‐1 domains (PDZ) that localizes at the basolateral membranes of polarized epithelial cells. Deregulation of its expression or localization leads to epithelial defects and tumorigenesis in part as a consequence of its repressive role on several signaling pathways including AKT, ERK, and HIPPO. In the present work, a proteomic approach is used to characterize the protein complexes associated to SCRIB and its paralogue LANO. Common and specific sets of proteins associated to SCRIB and LANO by MS are identified and an extensive landscape of their associated networks and the first comparative analysis of their respective interactomes are provided. Under proteasome inhibition, it is further found that SCRIB is associated to the β‐catenin destruction complex that is central in Wnt/β‐catenin signaling, a conserved pathway regulating embryonic development and cancer progression. It is shown that the SCRIB/β‐catenin interaction is potentiated upon Wnt3a stimulation and that SCRIB plays a repressing role on Wnt signaling. The data thus provide evidence for the importance of SCRIB in the regulation of the Wnt/β‐catenin pathway.     

Overexpression of Circular RNA ciRS‐7 Abrogates the Tumor Suppressive Effect of miR‐7 on Gastric Cancer via PTEN/PI3K/AKT Signaling Pathway

Gastric cancer (GC) has one of the highest mortality rates of malignancies globally. Currently, ciRS‐7, a novel circular RNA, has emerged as a potential sponge for miR‐7. However, few studies on ciRS‐7 in GC have been performed. In this study, we investigated the clinical significance and function of ciRS‐7 in GC. First, the expression levels of ciRS‐7 in 102 primary GC tissues and the matched para‐carcinoma tissues were evaluated and the clinical relevance was confirmed in an independent validation cohort (n = 154). Second, the effects of ciRS‐7 on miR‐7, PTEN, and PI3K were evaluated. Finally, the function of ciRS‐7 in GC was analyzed with cell lines and nude mice. The expression of ciRS‐7 was significantly upregulated in GC tissues compared with the matched para‐carcinoma tissues (P = 0.0023), and the upregulation of ciRS‐7 was linked to poor survival in the testing (P = 0.0143) and validation cohort (P = 0.0061). Multivariate survival analysis revealed that ciRS‐7 was probably an independent risk factor of overall survival (P < 0.05). Furthermore, overexpression of ciRS‐7 blocked the miR‐7‐induced tumor suppression in MGC‐803 and HGC‐27 cells and led to a more aggressive oncogenic phenotype, via antagonizing miR‐7‐mediated PTEN/PI3K/AKT pathway. ciRS‐7 may act as a prospective prognostic biological marker and a promising therapeutic target for GC. J. Cell. Biochem. 119: 440–446, 2018. © 2017 Wiley Periodicals, Inc.