TRIM25 activates AKT/mTOR by inhibiting PTEN via K63-linked polyubiquitination in non-small cell lung cancer.

The PTEN/AKT/mTOR signaling pathway is frequently dysregulated in non-small cell lung cancer (NSCLC), but the mechanisms are not well-understood. The present study found that the ubiquitin ligase TRIM25 is highly expressed in NSCLC tissues and promotes NSCLC cell survival and tumor growth. Mechanistic studies revealed that TRIM25 binds to PTEN and mediates its K63-linked ubiquitination at K266. This modification prevents the plasma membrane translocation of PTEN and reduces its phosphatase activity therefore accumulating PI(3,4,5)P3. TRIM25 thus activates the AKT/mTOR signaling. Moreover, we found that the antibacterial nitroxoline can activate PTEN by reducing its K63-linked polyubiquitination and sensitizes NSCLC to cisplatin-induced apoptosis. This study thus identified a novel modulation on the PTEN signaling pathway by TRIM25 and provides a potential target for NSCLC treatment.

Interleukin 22 Expands Transit-Amplifying Cells While Depleting Lgr5+ Stem Cells via Inhibition of Wnt and Notch Signaling.

BACKGROUND & AIMS: Epithelial regeneration is essential for homeostasis and repair of the mucosal barrier. In the context of infectious and immune-mediated intestinal disease, interleukin (IL) 22 is thought to augment these processes. We sought to define the mechanisms by which IL22 promotes mucosal healing. METHODS: Intestinal stem cell cultures and mice were treated with recombinant IL22. Cell proliferation, death, and differentiation were assessed in vitro and in vivo by morphometric analysis, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. RESULTS: IL22 increased the size and number of proliferating cells within enteroids but decreased the total number of enteroids. Enteroid size increases required IL22-dependent up-regulation of the tight junction cation and water channel claudin-2, indicating that enteroid enlargement reflected paracellular flux-induced swelling. However, claudin-2 did not contribute to IL22-dependent enteroid loss, depletion of Lgr5+ stem cells, or increased epithelial proliferation. IL22 induced stem cell apoptosis but, conversely, enhanced proliferation within and expanded numbers of transit-amplifying cells. These changes were associated with reduced wnt and notch signaling, both in vitro and in vivo, as well as skewing of epithelial differentiation, with increases in Paneth cells and reduced numbers of enteroendocrine cells. CONCLUSIONS: IL22 promotes transit-amplifying cell proliferation but reduces Lgr5+ stem cell survival by inhibiting notch and wnt signaling. IL22 can therefore promote or inhibit mucosal repair, depending on whether effects on transit-amplifying or stem cells predominate. These data may explain why mucosal healing is difficult to achieve in some inflammatory bowel disease patients despite markedly elevated IL22 production.

Retracted: microRNA-129-5p involved in the neuroprotective effect of dexmedetomidine on hypoxic-ischemic brain injury by targeting COL3A1 through the Wnt/ß-catenin signaling pathway in neonatal rats.

Our study aims to elucidate the mechanisms how microRNA-129-5p (miR-129-5p) involved in the neuroprotective effect of dexmedetomidine (DEX) on hypoxic-ischemic brain injury (HIBI) by targeting the type III procollagen gene (COL3A1) through the Wnt/ß-catenin signaling pathway in neonatal rats. A total of 120 rats were obtained, among which 15 rats were selected as sham group and rest rats as model, DEX, DEX + negative control (DEX + NC), DEX + miR-129-5p mimics, DEX + miR-129-5p inhibitors, DEX + XAV-939, and DEX + miR-129-5p inhibitors + XAV-939 groups. A dual-luciferase reporter assay was performed for the target relationship between miR-129-5p and COL3A1. Weight rate and water content of cerebral hemisphere were detected. Quantitative real-time polymerase chain reaction and Western blot analysis were conducted to detect miR-129-5p expression and expressions of COL3A1, E-cadherin, T-cell factor (TCF)- 4, and ß-catenin. The DEX, DEX + miR-129-5p mimics, DEX + XAV-939 groups had increased weight rate of the cerebral hemisphere, but decreased water content of left cerebral hemisphere, levels of COL3A1, ß-catenin, TCF-4, and E-cadherin in the hippocampus compared with the model and DEX + miR-129-5p inhibitors groups. COL3A1 was verified as the target gene of the miR-129-5p. Compared with the DEX + NC and DEX + miR-129-5p inhibitors + XAV-939 groups, the DEX + XAV-939 and DEX + miR-129-5p mimics groups had elevated weight rate of the cerebral hemisphere, but reduced water content of left cerebral hemisphere, levels of COL3A1, ß-catenin, TCF-4, and E-cadherin in the hippocampus. Our findings demonstrate that miR-129-5p improves the neuroprotective role of DEX in HIBI by targeting COL3A1 through the Wnt/ß-catenin signaling pathway in neonatal rats.

Silencing of long noncoding RNA MEG3 enhances cerebral protection of dexmedetomidine against hypoxic-ischemic brain damage in neonatal mice by binding to miR-129-5p.

Hypoxic-ischemic brain damage (HIBD) is a leading cause of neonatal acute mortality and chronic nervous system injury. Recently, it has been found that long noncoding RNAs (lncRNAs) play a significant role in the neurodevelopment and etiopathogenesis of HIBD. Here, the researchers aimed to determine the role of lncRNA maternally expressed gene (MEG3) in the therapeutic effect of dexmedetomidine (DEX) in neonatal mice with HIBD through the regulation of microRNA-129-5p (miR-129-5p). HIBD models were established in C57/BL6 neonatal mice. Subsequently, the target relationship between MEG3 and miR-129-5p was predicted and verified. The neonatal mice were injected with DEX, ad-shMEG3, and mimics and inhibitors of miR-129-5p to identify roles of MEG3 and miR-129-5p in therapeutic effects of DEX on neuronal apoptosis and injury, cerebral atrophy, and learning and memory ability of neonatal mice with HIBD. MEG3 directly targeted and inhibited the expression of miR-129-5p. Silencing of MEG3 or upregulation of miR-129-5p effectively promoted the therapeutic effect of DEX on neonatal mice with HIBD. Silencing of MEG3 or upregulation of miR-129-5p reduced the neuronal apoptosis rate and degree of cerebral atrophy, and also enhanced the learning and memory ability of HIBD neonatal mice. Collectively, the key findings obtained from the present study support the notion that MEG3 silencing enhances the therapeutic effect of DEX on neonatal mice with HIBD by binding to miR-129-5p.

In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability.

The intestinal barrier defends against pathogenic microorganism and microbial toxin. Its function is regulated by tight junction permeability and epithelial cell integrity, and disruption of the intestinal barrier function contributes to progression of gastrointestinal and systemic disease. Two simple methods are described here to measure the permeability of intestinal epithelium. In vitro, Caco-2BBe cells are plated in tissue culture wells as a monolayer and transepithelial electrical resistance (TER) can be measured by an epithelial (volt/ohm) meter. This method is convincing because of its user-friendly operation and repeatability. In vivo, mice are gavaged with 4 kDa fluorescein isothiocyanate (FITC)-dextran, and the FITC-dextran concentrations are measured in collected serum samples from mice to determine the epithelial permeability. Oral gavage provides an accurate dose, and therefore is the preferred method to measure the intestinal permeability in vivo. Taken together, these two methods can measure the permeability of the intestinal epithelium in vitro and in vivo, and hence be used to study the connection between diseases and barrier function.

Neuroprotective effects of dexmedetomidine on traumatic brain injury: Involvement of neuronal apoptosis and HSP70 expression.

The aim of the present study was to investigate the protective effect of dexmedetomidine (Dex) on traumatic brain injury (TBI), and further evaluate whether the underlying neuroprotective mechanisms are associated with neurological apoptosis and the expression of 70 kDa heat shock protein (HSP70) in the hippocampus. A total of 90 adult male Sprague­Dawley rats were randomly assigned into 3 groups (n=30/group): Sham, TBI and Dex groups. The rat models of TBI were established using a modified weight­drop device and Dex (15 µg/kg) was intravenously administered immediately following TBI. The brain edema and neurological function outcomes of TBI were assessed using wet­dry weight analysis and the Neurological Severity Score method. The expression levels of B­cell lymphoma­2 (Bcl­2) and Bcl­2­associated X protein (Bax) in the rat hippocampus were evaluated using immunohistochemical staining and western blot analysis. The protein levels of HSP70 in the hippocampal region were analyzed using western blot analysis. The results of the present study revealed that administration of Dex post­TBI improved brain edema and neurological outcomes, due to the attenuation of the TBI­induced reduction of Bax expression and increase of Bcl­2 and HSP70 expression. In conclusion, the results of the present study suggested that administration of Dex may serve as a neuroprotective agent against brain injury, at least partially via the inhibition of neuronal apoptosis and upregulation of HSP70 expression in the hippocampus.

Dexmedetomidine exerts neuroprotective effect via the activation of the PI3K/Akt/mTOR signaling pathway in rats with traumatic brain injury.

OBJECTIVE: This study aims to explore the neuroprotective effects of dexmedetomidine (Dex) in rats suffering from traumatic brain injury (TBI) via the PI3K/Akt/mTOR signaling pathway. METHODS: A weight drop model was performed for TBI model establishment. A total of 150 Sprague Dawley rats were selected and assigned into control, sham, TBI, TBI+Dex, TBI+LY294002 (LY) and TBI+Dex+LY groups. Modified Neurological Severity Score (mNSS) was conducted in order to evaluate the neurological injury. The water content in brain tissues was measured. The expressions of PI3K/Akt/mTOR signaling pathway-related proteins, tight junction proteins (ZO-1 and Claudin-5) and autophagy proteins (LC3 I/II and Beclin-1) were detected using Western blot assay. A TUNEL assay was applied for cell apoptosis, immunofluorescence was employed for the detection of the positive expression of LC3, and ELISA was applied for detection of levels of inflammatory factors [tumor necrosis factor-alph (TNF-a), interleukin-1ß (IL-1ß), interferon-γ (INF-γ) as well as IL-6], respectively. RESULTS: Compared with the control group, the other four groups exhibited increased mNSS, brain water content, expression of LC3, TNF-a, IL-1ß, INF-γ and IL-6, and positive expression of LC3, expression of LC3 I/II and Beclin-1, but decreased expression of pp-PI3K/t-PI3K, p-Akt/t-Akt, p-mTOR/t-mTOR, ZO-1 and Claudin-5. Compared with the TBI group, the TBI+Dex group exhibited reduced mNSS, brain water content, expression of LC3, TNF-a, IL-1ß, INF-γ and IL-6, positive expression of LC3, as well as expression of LC3 I/II and Beclin-1 but demonstrated an elevated expression of pp-PI3K/t-PI3K, p-Akt/t-Akt, p-mTOR/t-mTOR, ZO-1 and Claudin-5, while opposite trends were observed in the TBI+LY group. The TBI+Dex group exhibited reduced mNSS, brain water content, expression of LC3, TNF-a, IL-1ß, INF-γ and IL-6, positive expression of LC3, as well as expression of LC3 I/II and Beclin-1 but demonstrated an elevated expression of pp-PI3K/t-PI3K, p-Akt/t-Akt, p-mTOR/t-mTOR, ZO-1 and Claudin-5, while opposite trends were observed in the TBI+LY group, as compared with the TBI+Dex+LY group. CONCLUSION: The data shows that Dex exerts a neuroprotective effect via the activation of the PI3K/Akt/mTOR signaling pathway in rats with TBI.

MiR-155 up-regulated by TGF-ß promotes epithelial-mesenchymal transition, invasion and metastasis of human hepatocellular carcinoma cells in vitro.

It has previously been reported that microRNA (miR)-155 is linked to the recurrence and prognosis of hepatocellular carcinoma (HCC) following liver transplantation. However, the role of miR-155 in the invasion and metastasis of HCC cells remains largely unclear. The aim of this study was to investigate the expression of miR-155 in HCC cells and its role in the invasion and migration of HCC cells in vitro. We found that the level of expression of miR-155 in HCC tissues and cells was significantly increased compared with non-tumorous adjacent tissues. Further study revealed that recombinant human transforming growth factor-ß (TGF-ß1) up-regulated the expression of miR-155 in HCC cells in vitro. Further, the overexpression of miR-155 in HCC cell line Huh-7 led to increased levels of cell invasion and migration compared with untreated control Huh-7 cells. MiR-155-overexpressed Huh-7 cells also exhibited altered levels of expression of certain cellular adhesion molecules related to epithelial-mesenchymal transition (EMT), including low levels of CDH1 and higher levels of FN1, SNAI1 and ZEB1, compared with control Huh-7 cells. Moreover, it was found that the overexpression of miR-155 and of TGF-ß1 protein decreased the expression of E-Cadherin and increased the expression of Vimentin in Huh-7 cells. These results indicate that an increased level of miR-155 in HCC cells, possibly due to stimulation by TGF-ß1, accelerates the process of EMT, promotes cellular invasion and migration in vitro, and thereby further promotes the progression of HCC.

[Hypoxia promotes the growth and invasiveness of prostate cancer cells by down-regulating miR-132 in vitro].

OBJECTIVE: To explore the expression of miR-132 in prostate cancer and its effects on the growth and invasiveness of prostate cancer cells and the influence of hypoxia on the level of miR-132 and biological behavior of prostate cancer cells. METHODS: Real time PCR was used to measure the expression level of miR-132 in the prostate cancer tissue, analyze its relationship with the clinical stage and Gleason score of prostate cancer, and determine the influence of hypoxia on the miR-132 level in the human prostate cancer PC3 cell line in vitro. Sulfor-hodamine B chromatometry and Matrigel invasion assay were employed to detect the effects of hypoxia and miR-132 mimic plasmid transfection on the viability and invasiveness of PC3 cells in vitro. RESULTS: The miR-132 level in the prostate cancer was significantly declined to 52.38% (in T1－T2 stages) and 21.59% (in T3－T4 stages) of that in the cancer-adjacent tissue (both P<0.01). In hypoxia, the expression of miR-132 was significantly decreased in the PC3 cells (P<0.01). After 48 and 72 hours of transfection with miR-132 mimic plasmid, the viability of the PC3 cells was markedly reduced (P<0.05 or P<0.01), and their invasiveness decreased by 57.5% after 48 hours (P<0.01). However, there was no significant difference in the viability or invasiveness of the PC3 cells transfected with miR-132 mimic plasmid between normoxia and hypoxia. CONCLUSIONS: The reduced expression of miR-132 is closely related to the clinical stage and Gleason score of prostate cancer. Hypoxia increases the viability and invasiveness of prostate cancer cells in vitro by down-regulating the expression of miR-132 and consequently may promote the growth and metastasis of prostate cancer.

[Downregulation of PAR expression induces the apoptosis of human prostate cancer PC3 cells and increases the Bcl-2/Bax ratio].

OBJECTIVE: To investigate the effects of the downregulated expression of the prostate androgen regulated (PAR) gene on the cell cycle and apoptosis of PC3 cells as well as on the expression level of Bcl-2/Bax. METHODS: After transfecting PC3 cells with small interfering RNA (siRNA) targeting PAR, we detected the inhibitory effect of PAR depletion on the proliferation of the PC3 cells by MTT assay, determined their apoptosis by flow cytometry, and measured the expression levels of Bcl-2 and Bax by Western blot. RESULTS: The expression of PAR was suppressed by siRNA, the G2-M phase PC3 cells were increased to (29.95 +/- 3.25)%, and the apoptosis of the cells was enhanced to (20.61 +/- 2.73)%, with statistically significant difference from the control group (P < 0.01). Western blot showed a decreased expression of Bcl-2, an increased expression of Bax, and an elevated ratio of Bax to Bcl-2. CONCLUSION: Downregulation of the PAR expression increases the Bax/Bcl-2 ratio and Bax expression, and thus induces the G2-M phase arrest and apoptosis of PC3 cells.

[The deletion of La protein binding site in HBV RNA leads to instability of S gene mRNA].

OBJECTIVE: To investigate the effect of deletion of the La protein binding site of HBV RNA, caused by its mutation, on the HBV S-mRNA stability of S gene, to study the role of the site in hepatitis B virus life cycle, and to try to find a new anti-HBV target in the future. METHODS: A HBV vector with mutation related to the La protein binding site was constructed using molecular cloning and PCR based site directed mutagenesis, and the vector was named pHBV-mLa. The HBV RNA secondary structure of the site was calculated using a computer. Normal HBV vectors and mutant vectors were respectively transfected into HepG2 cells by Lipofectamine 2000. HBV S-mRNA levels in the two groups were analyzed using semi-quantitative RT-PCR, and HBsAg secretion into the culture media was tested using ELISA. RESULTS: A HBV vector with mutation related to the La protein binding site was successfully constructed, and it was identified and confirmed using restriction analysis and sequencing. The HBV RNA secondary structure of the mutant vector was completely different to the stem-loop structure of the normal HBV vector. Semi-quantitative RT-PCR and ELISA analyses showed that the level of HBV S-mRNA in the mutant vector group was significantly lower than that in the normal HBV vector group (t'=12.703, P<0.05), and the expression efficacy of HBsAg was reduced in the mutant vector group (t= 44.648, P<0.01). CONCLUSIONS: The change of La protein binding site in the HBV RNA caused by the mutation in HBV DNA disorganizes the stem-loop structure in the HBV RNA site. With the structural change, the La protein cannot bind the site and stabilize the HBV RNA (HBV S-mRNA), as the cleavage site in the upstream of the stem-loop structure is exposed to endoribonuclease. This results in HBV S-mRNA decay and affects the expression of the S gene. This study shows that only the sequence of this site in the HBV DNA is reserved, then the stem-loop structure in the La protein binding site will remain intact, and the disorganization of the stem-loop structure affects the stability of the transcripted HBV RNA. The La protein binding site in HBV RNA and the special secondary structure of the site are crucial to the life cycle of the hepatitis B virus.

[The relationship between the plasma homocysteine level and the polymorphism of MTHFR gene C667T in liver cirrhosis].

OBJECTIVE: To study the relationship between the plasma homocysteine (HCY) level and the polymorphism of N(5), N(10)-methylenetetrahydrofolate reductase (MTHFR) gene C667T in liver cirrhosis. METHODS: 112 normal subjects and 87 liver cirrhosis patients were recruited in the study. Their plasma HCY levels were measured using high performance liquid chromatography with fluorescence detection and polymorphisms of their MTHFR gene were analyzed using PCR-RFLP. RESULTS: The mean level of plasma HCY was significantly higher in patients with liver cirrhosis (21.71+/-4.86) micromol/L than that in healthy individuals (8.34+/-3.59) micromol/L. There were three kinds of MTHFR genotypes: +/+ (TT, homozygous mutation), +/- (CT, heterozygous mutation) and -/- (CC, wild type). The frequencies of the three genotypes were as follows: +/+, 29.9%; +/-, 52.9%; -/-, 17.2% in cirrhosis patients and +/+, 19.6%; +/-, 33.9%; -/-, 46.4% in normal subjects. The frequency of homozygous or heterozygous mutation was significantly higher in cirrhosis patients than that in the normal control. Moreover, plasma homocysteine level was markedly higher in patients with MTHFR genetic mutation than those without mutation. CONCLUSIONS: Hyperhomocysteinemia may be an independent risk factor for liver cirrhosis. MTHFR is the main enzyme related to homocysteine metabolism. The genetic mutation of MTHFR C667T is possibly an important mechanism of hyperhomocysteinemia in liver cirrhosis. The level of plasma homocysteine may be an early indicator for liver cirrhosis.

Establishment of a screening system for selection of siRNA target sites directed against hepatitis B virus surface gene.

To study the inhibitory effects of plasmid-derived small interfering RNA (siRNA) and synthetic siRNA on the expression of the hepatitis B virus surface (HBs) gene, three plasmid-derived siRNAs and one synthetic siRNA that complement the coding region of the HBs gene were prepared. The HBs expression plasmid pHBs-EGFP was also constructed. HeLa cells were co-transfected with pHBs-EGFP and the above siRNAs. The HBs mRNA quantities were measured by reverse-transcription PCR, and the level of HBs-EGFP fusion protein was quantified by fluorescent microscope. The concentrations of the hepatitis B virus surface antigen (HBsAg) derived from the culture supernatant of transfected HepG2.2.15 cells were measured by an enzyme-linked immunosorbent assay (ELISA) kit. The results showed that the three plasmid-derived siRNAs and the synthetic siRNA can effectively reduce the quantities of HBs mRNA and protein. The plasmid-derived siRNA psiRNA1 was found to be the most effective inhibitor of HBs expression. It can inhibit HBs-EGFP expression by 63.3% and suppress HBs mRNA by 75.6%. To further substantiate the above observations, psiRNA1 was transfected into HepG2.2.15 cells (an HBV secreting cell line). The transfections resulted in almost complete blockage of HBsAg production, whereas control vector-transfected cells secreted high levels of HBsAg 7 days post-transfection. In conclusion, our data suggests that RNA interference (RNAi) is an efficient approach for reducing the level of HBs transcripts and proteins and for suppressing HBsAg production.