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In this study, we aimed to study the role of growth factor receptor-bound protein 2 (Grb2) in palmitic acid-induced steatosis and other "fatty liver" symptoms in vitro. HepG2 cells, with or without stably suppressed Grb2 expression, were incubated with palmitic acid for 24 h to induce typical clinical "fatty liver" features, including steatosis, impaired glucose metabolism, oxidative stress, and apoptosis. MTT and Oil Red O assays were applied to test cell viability and fat deposition, respectively. Glucose uptake assay was used to evaluate the glucose utilization of cells. Quantitative polymerase chain reaction and Western blot were used to measure expressional changes of key markers of insulin signaling, lipid/glucose metabolism, oxidative stress, and apoptosis. After 24-h palmitic acid induction, increased fat accumulation, reduced glucose uptake, impaired insulin signaling, enhanced oxidative stress, and increased apoptosis were observed in HepG2 cells. Suppression of Grb2 in HepG2 significantly reduced fat accumulation, improved glucose metabolism, ameliorated oxidative stress, and restored the activity of insulin receptor substrate-1/Akt and MEK/ERK pathways. In addition, Grb2 deficiency attenuated hepatic apoptosis shown by reduced activation of caspase-3 and fluorescent staining. Modulation of Bcl-2 and Bak1 also contributed to reduced apoptosis. In conclusion, suppression of Grb2 expression in HepG2 cells improved hepatic steatosis, glucose metabolism, oxidative stress, and apoptosis induced by palmitic acid incubation partly though modulating the insulin signaling pathway.

Aurora kinase A (AURKA) is an oncogenic serine/threonine kinase, it plays important roles in tumorigenesis and chemoresistance. In this study, we investigated the expression of AURKA in lung adenocarcinoma tissues, the role of small interference RNA targeting AURKA on growth, cell cycle, and apoptosis of lung adenocarcinoma cell lines in vitro. The AURKA is highly expressed in lung adenocarcinoma tissues and human lung adenocarcinoma cell lines. Lentivirus-mediated short hairpin RNA (shRNA) was used to knock down AURKA expression in human lung adenocarcinoma cell lines H1299 and A549. The results indicated that depletion of AURKA could inhibit cell growth, cause cell cycle arrest and apoptosis. The potential mechanisms of AURKA inhibition induced cell cycle arrest and apoptosis are associated with downregulated RAF-1, CCND2, CCND3, CDK4, PAK4, EGFR and upregulated WEE1 expression. Furthermore, AURKA knockdown cooperated with vincristine (VCR) to repress A549 cell proliferation. Therefore, AURKA plays important roles in the proliferation of human lung adenocarcinoma cells, which suggests that AURKA could be a promising tool for lung adenocarcinoma therapy.

STAT3 (Signal transducer and activator of transcription 3) is a key transcription factor of the JAK-STAT (Janus kinase/signal transducer and activator of transcription) pathway that regulates cell proliferation and apoptosis. Activation of STAT3 is under tight regulation, and yet the different signaling pathways and the mechanisms that regulate its activity remain to be elucidated. Using a yeast two-hybrid screening, we have identified a nuclear protein I{kappa}B-{zeta} that interacts in a novel way with STAT3. This physical interaction was further confirmed by co-immunoprecipitation assays. The interaction regions were mapped to the coiled-coil domain of STAT3 and the C-terminal of I{kappa}B-{zeta}. Overexpression of I{kappa}B-{zeta} inhibited the transcriptional activity of STAT3. It also suppressed cell growth and induced cell apoptosis in SRC-simulated cells, which is partially mediated by down-regulation of expression of a known STAT3 target gene, MCL1. Our results suggest that I{kappa}B-{zeta} is a negative regulator of STAT3, and demonstrate a novel mechanism in which a component of the NF-{kappa}B signaling pathway inhibits the activation of STAT3.

The aim of the present study was to evaluate the effects of S100A10 silencing on the inflammatory response in human chondrocytes (HCs).The inflammation induced by lipopolysaccharide (LPS) was investigated in HCs in which the S100A10 was blocked with a lentiviral shRNA vector. A lentiviral shRNA vector targeting S100A10 was constructed and packaged to effectively block S100A10 expression in HCs. HCs were infected with the lentivirus. S100A10 expression levels in HCs were detected by western blot analysis. Enzyme-linked immunosorbent assay (ELISA) was employed to evaluate the change of cytokine secretion levels. The effects of S100A10 silencing on the activation of mitogen-activated protein kinases (MAPKs) and NF-κB signaling pathway were also determined by western blot analysis. In addition, fluo-3-AM was used to demonstrate the change in calcium mobilization. Lentivirus effectively infected the HCs and inhibited the expression of S100A10. HCs with downregulated S100A10 showed significantly decreased production of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-10. S100A10 silencing markedly suppressed the activation of MAPKs induced by LPS. Furthermore, the calcium concentration increase in HCs stimulated by LPS was also inhibited by S100A10 knockdown. Our investigation demonstrated that S100A10 might be considered as a potential target for anti-inflammatory treatment.

Bax-interacting factor-1 (Bif-1) interacts with Beclin1 [the mammalian ortholog of yeast autophagy-related gene 6 (Atg6)] and affects the formation of autophagosomes during autophagy. The aim of this study was to explore Bif-1 expression and its prognostic significance in comparison with various clinicopathological predictors of survival. Bif-1 protein expression was determined by immunohistochemistry in 206 hepatocellular carcinomas. Cytoplasmic immunoreactivity was scored semi-quantitatively. The results were analyzed in correlation with various clinicopathological characteristics, including patient survival. The Chi-square test and Kaplan-Meier survival analysis were applied. The expression of Bif-1 was significantly higher in the hepatocellular cancers than in the adjacent matched non-tumor tissues (51.5 vs. 33.0%, P

STAT3 (Signal transducer and activator of transcription 3) is a key transcription factor of the JAK-STAT (Janus kinase/signal transducer and activator of transcription) pathway that regulates cell proliferation and apoptosis. Activation of STAT3 is under tight regulation, and yet the different signaling pathways and the mechanisms that regulate its activity remain to be elucidated. Using a yeast two-hybrid screening, we have identified a nuclear protein IkappaB-zeta that interacts in a novel way with STAT3. This physical interaction was further confirmed by co-immunoprecipitation assays. The interaction regions were mapped to the coiled-coil domain of STAT3 and the C-terminal of IkappaB-zeta. Overexpression of IkappaB-zeta inhibited the transcriptional activity of STAT3. It also suppressed cell growth and induced cell apoptosis in SRC-simulated cells, which is partially mediated by down-regulation of expression of a known STAT3 target gene, MCL1. Our results suggest that IkappaB-zeta is a negative regulator of STAT3, and demonstrate a novel mechanism in which a component of the NF-kappaB signaling pathway inhibits the activation of STAT3.