Overexpression of Parkin in clear cell renal cell carcinoma decreases tumor aggressiveness by regulating CKS2 levels.

Low expression levels of the E3 ubiquitin­protein ligase Parkin (PARK2) are exhibited in several cancer entities, including clear cell renal cell carcinoma (ccRCC), and are associated with poor prognosis; however, PARK2 can also function as a tumor suppressor gene. The aim of the present study was to thoroughly investigate the effects of PARK2 overexpression in ccRCC cell lines and to determine its effects on malignancy by conducting functional assays such as cell cycle analysis, apoptosis analysis, migration and invasion assays. Furthermore, liquid chromatography­mass spectrometry was used to decipher potential targets of PARK2 that may influence the behavior of ccRCC tumor cells. In addition, ccRCC tumor tissues from a patient cohort were examined in tissue microarrays to find correlations between different clinical parameters. In the present study, it was demonstrated that the induction of PARK2 resulted in a less aggressive phenotype, as indicated by lower migration and invasion in ccRCC cell lines. Mass spectrometry revealed decreased levels of 29 proteins in cells with PARK2 overexpression, including CDC28 protein kinase regulatory subunit 2 (CKS2), which is highly expressed in numerous types of cancer. The link between the function of PARK2 as an E3 ubiquitin ligase and the low expression levels of CKS2 was investigated by mutating the catalytic domain of the PARK2 gene, and it was found that the effect of decreased migration was abolished in 786­O and RCC­MH ccRCC cell lines. CKS2 silencing decreased migratory ability of the cells. Furthermore, it was revealed that high CKS2 levels are associated with high tumor grading in patient samples and lower patient survival. In conclusion, the results from the present study indicated that PARK2 may signal via CKS2 to affect tumor behavior. In consequence, CKS2 may be a biomarker in ccRCC and may also serve as potential target for ccRCC therapy.

PTEN-Induced Putative Kinase 1 (PINK1)/Parkin-Mediated Mitophagy Protects PC12 Cells Against Cisplatin-Induced Neurotoxicity.

BACKGROUND The pathogenesis of chemotherapy-induced neuropathy, a dose-dependent adverse effect of cisplatin, involves mitochondrial dysfunction. PTEN-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy removes damaged mitochondria under various pathological conditions. The objective of this study was to determine mitophagy status and its effects on mitochondrial function and neuronal cell damage after cisplatin treatment using an in vitro model of cisplatin-induced neurotoxicity. MATERIAL AND METHODS PC12 cells were transfected with Parkin or Parkin siRNA using lentiviral particles and Lipofectamine 3000™, respectively, and then were exposed to 10 µM cisplatin. The expression of autophagic proteins was measured by Western blot analysis. Mitophagy in PC12 cells was detected by confocal microscopy analysis of mitochondria-lysosomes colocalization and autophagic flux. The effects of PINK1/Parkin-mediated mitophagy on cisplatin-induced neurotoxicity were assessed via mitochondrial function, neuritic length, nuclear diameter, and apoptosis. RESULTS Cisplatin activated PINK1/Parkin-mediated mitophagy in PC12 cells. Autophagic flux analysis revealed that cisplatin inhibits the late stage of the autophagic process. The knockdown of Parkin suppressed cisplatin-induced mitophagy, aggravating cisplatin-induced depolarization of mitochondria, cellular ATP deficits, reactive oxygen species outburst, neuritic shortening, nuclear diameter reduction, and apoptosis, while Parkin overexpression enhanced mitophagy and reversed these effects. CONCLUSIONS PINK1/Parkin-regulated mitophagy can protect against cisplatin-related neurotoxicity, suggesting therapeutic enhancement of mitophagy as a potential intervention for cisplatin-induced peripheral neuropathies. The interference of cisplatin with autophagosome-lysosome fusion may be partly responsible for cisplatin-induced neurotoxicity.

Grail attenuates influenza A virus infection and pathogenesis by inhibiting viral nucleoprotein.

Grail is a well-characterized mediator of metabolic disease, tumour progression, and immune response. However, its role in influenza A virus (IAV) infection remains poorly understood. In this study, we demonstrated that Grail knockdown potentiates IAV infection, whereas Grail overexpression blocks IAV replication. The intranasal administration of IAV to Grail KO mice led to a lower survival rate than in similarly infected wild-type mice. Additionally, IAV-infected Grail KO mice had higher viral titres, greater immune cell infiltration, and increased expression of inflammatory cytokines in the lungs. Mechanistically, we showed that Grail interacts with viral nucleoprotein (NP), targeting it for degradation and inhibiting IAV replication. NP expression was increased in Grail knockdown cells and reduced in cells overexpressing Grail. Collectively, our results demonstrate that Grail acts as a negative regulator of IAV infection and replication by degrading viral NP. These data increase our understanding of the host antiviral response to infection with IAV.

[Effect of RAD18-siRNA on proliferation and chemotherapy sensitivity of human esophageal squamous cell carcinoma ECA-109 cells].

Objective: To investigate the effect of RAD18-siRNA on cell proliferation and chemotherapy sensitivity of esophageal squamous cell carcinoma (ESCC) ECA-109 cells. Methods: RAD18-siRNA was transfected into human ECA-109 cells by Lipofectamine 3000. Quantitative PCR and Western blot were performed to detect RAD18 and CyclinD1 expression; CCK-8 assay was used to determine cell proliferation and chemotherapy drug sensitivity; flow cytometry was used to determine cell cycle. Correlation between RAD18 and CyclinD1 mRNA expression was analyzed by Pearson's correlation. Results: Compared with non-transfected cells, the expression of RAD18 in RAD18-siRNA group was significantly decreased (P<0.05). The cell proliferation was inhibited (P<0.05) and the cell number of G1 phase was increased, G2/M phase cells decreased (P<0.05) in RAD18-siRNA group. After treatment with different concentrations of cisplatin or 5-FU, the survival rate of the two cell groups was reduced (all P<0.05), and the IC50 of RAD18-siRNA group was significantly lower than that of non-transfected group (P<0.05). The mRNA expression of RAD18 was positively correlated with CyclinD1 expression in ESCC tissues(r=0.478, P<0.01). Conclusion: Down-regulated expression of RAD18 can decrease the cell proliferation and increase chemo-sensitivity of ESCC cells, and CyclinD1 may participate in the process.

Associations between maternal antioxidant intakes in pregnancy and infant allergic outcomes.

Antioxidant intakes in pregnancy may influence fetal immune programming and the risk of allergic disease. We investigated associations between maternal intakes of ß-carotene, vitamin C, vitamin E, copper and zinc, and infant allergic outcomes. Antioxidant intakes of pregnant women (n = 420) assessed prospectively by a food frequency questionnaire, were examined in relation to allergic outcomes at 1 year of age (n = 300). The main relationships with allergic outcomes were seen with dietary vitamin C and copper. Specifically, higher maternal dietary vitamin C intake was associated with a reduced risk of any diagnosed infant allergic disease and wheeze. After adjustment for potential confounders the relationship with wheeze remained statistically significant. There was also an inverse linear relationship between vitamin C and food allergy. Higher dietary copper intake was associated with reduced risk of eczema, wheeze and any allergic disease. The relationship with wheeze and any allergic disease remained statistically significant in multivariate analysis, and there was also an inverse linear relationship between copper and food allergy. However, these relationships were only seen for nutrients present in food. There were no relationships between ß-carotene, vitamin E or zinc and any allergic outcomes. In summary, this study suggests that maternal diet of fresh foods rich in vitamin C is associated with reduced risk of infant wheeze, and that copper intake is associated with reduced risk of several allergic outcomes.

Inhibition of MHC class II expression and immune responses by c-MIR.

We previously reported a novel E3 ubiquitin ligase (E3), designated as c-MIR, which targets B7-2 to lysosomal degradation and down-regulates the B7-2 surface expression through ubiquitination of its cytoplasmic tail. B7-2 is well known as a costimulatory molecule for Ag presentation, suggesting that the manipulation of c-MIR expression modulates immune responses in vivo. To examine this hypothesis, we generated genetically modified mice in which c-MIR was expressed under an invariant chain (Ii) promoter. Dendritic cells derived from genetically engineered mice showed low ability to present Ags. In addition, these mice showed resistance to the onset of experimental autoimmune encephalomyelitis and an impaired development of CD4 T cells in the thymus and the periphery. These findings led us to conclude that MHC class II (MHC II) is an additional target for c-MIR. Indeed, forced expression of c-MIR in several B cell lines down-regulated the surface expression of MHC II, and down-regulation was found to depend on the presence of a single lysine residue in the cytoplasmic tail of the I-A beta-chain. In a reconstitution system using 293T cells, we found that the lysine residue at position 225 in the I-A beta-chain was ubiquitinated by c-MIR. To our knowledge, c-MIR is the first example of an E3 that is capable of inhibiting MHC II expression. Our findings suggest that c-MIR might potently regulate immune responses in vivo.