Zhenzhong Su

Ku80 is highly expressed in lung adenocarcinoma and promotes cisplatin resistance

BackgroundKu80 is crucially implicated in DNA repair, apoptosis, and chemoresistance. In this study, we aimed to assess the expression of Ku80 in clinical lung adenocarcinoma specimens, and investigate its role in the regulation of cisplatin sensitivity in cisplatin resistant human lung adenocarcinoma cells A549/DDP.MethodsTumor specimens and medical records of 106 patients with operable lung adenocarcinoma were obtained from 1998 to 2003. Ku80 mRNA and protein levels of the tumor samples, cultured human lung adenocarcinoma cells A549 cells and their cisplatin resistant variant A549/DDP cells were examined by reverse transcription PCR and western blot analysis. Ku80-specific siRNA or control scramble siRNA was transfected into A549/DDP cells, then cell sensitivity to cisplatin was examined by 3-(4,5-dimethylthia-zol-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis was assessed by flow cytometric analysis. In addition, the levels of cleaved caspase-3 and cleaved PARP in the treated cells were detected by western blot analysis.ResultsTotal 83.3% (20/24) cisplatin-resistant tumors had high Ku80 expression, while 8.3% (4/48) cisplatin-sensitive tumors had high Ku80 expression (p < 0.01). Univariate analysis indicated that overall survival and progression-free survival were significantly better in lung adenocarcinoma patients with low vs. high Ku80 expression level (p < 0.01). Ku80 mRNA and protein expression levels were significantly increased in A549/DDP cells compared to parental A549 cells. siRNA mediated knockdown of Ku80 resensitized A549/DDP cells to cisplatin-induced apoptosis.ConclusionsKu80 expression level could predict the outcome and the sensitivity to cisplatin-based chemotherapy in patients with lung adenocarcima. Ku80-siRNA could be utilized as a therapeutic strategy to resensitize nonresponders to cisplatin.

RNA-binding motif protein 5 negatively regulates the activity of Wnt/β-catenin signaling in cigarette smoke-induced alveolar epithelial injury

Cigarette smoking is closely associated with various respiratory diseases. Oxidants and carcinogens in cigarettes are reported to induce various airway epithelial injuries. However, the underlying mechanisms remain unclear. The aims of the present study were to determine the involvement of RNA-binding motif protein 5 (RBM5) and Wnt/β-catenin signaling in cigarette smoke-induced alveolar epithelial injury, as well as the interaction between both. A549 cells were treated with cigarette smoke extract (CSE). The MTT assay was used to assess the effects of CSE on cell viability. The levels of RBM5 and Wnt/β-catenin/GSK3β were detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. A luciferase assay was used to assess the activity of β-catenin/T-cell factor (TCF) signaling. The results revealed that CSE inhibited A549 cell viability in both a dose- and time-dependent manner. Cytosolic and nuclear β-catenin levels were significantly increased following CSE treatment, compared with those in the control cells (P<0.05). The luciferase activity in CSE-exposed cells transfected with the TCF luciferase reporter wild-type plasmid (pGL3-OT) was significantly greater than that in cells without CSE exposure (33,167±3,085 vs. 19,978±1,916, respectively, P<0.05). Both the mRNA and protein levels of RBM5 in the CSE-treated cells were significantly reduced compared to the levels in the controls (all P<0.05). The overexpression of RBM5 inhibited Wnt/β-catenin signaling in the A549 cells, while silencing of RBM5 enhanced Wnt/β-catenin signaling. The β-catenin/TCF signaling inhibitor ICG-001 had no apparent effect on the RBM5 levels. Downregulation of RBM5 and activation of Wnt/β-catenin signaling are involved in CSE-induced alveolar epithelial injury. RBM5 acts as an upstream molecule that negatively regulates the activity of Wnt/β-catenin signaling.

Lentiviral vector-mediated RBM5 overexpression downregulates EGFR expression in human non-small cell lung cancer cells

BackgroundRNA binding motif 5 (RBM5) is a tumor suppressor gene that modulates apoptosis through the regulation of alternative splicing of apoptosis-related genes. Our previous studies suggested that RBM5 expression was negatively correlated with the expression of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) tissues. This study was aimed at determining whether RBM5 is able to regulate EGFR expression.MethodsBoth in vitro and in vivo studies were carried out to determine the effect of RBM5 on the expression of EGFR. Lentiviral vector-mediated RBM5 overexpression was employed in lung adenocarcinoma cell line A549. A549 xenograft mice were treated with recombinant RBM5 plasmid carried by attenuated Salmonella typhi Ty21a. Real-time quantitative polymerase chain reaction and Western blot were carried out to detect RBM5 and EGFR expression.ResultsBoth in vivo and in vitro studies indicated that the expression of EGFR mRNA and protein was decreased significantly in the RBM5 overexpression group compared to control groups as shown by real-time PCR and Western blot analysis. We identified that RBM5 overexpression inhibited EGFR expression both in A549 cells and in A549 xenograft mice model.ConclusionsOur study demonstrated that EGFR expression is regulated by RBM5 in lung adenocarcinomas cells either in a direct or indirect way, which might be meaningful with regards to target therapy in lung cancer.

RNA-binding motif protein 5 inhibits the proliferation of cigarette smoke-transformed BEAS-2B cells through cell cycle arrest and apoptosis

Cigarette smoking has been shown to be the most significant risk factor for lung cancer. Recent studies have also indicated that RNA-binding motif protein 5 (RBM5) can modulate apoptosis and suppress tumor growth. The present study focused on the role of RBM5 in the regulation of cigarette smoke extract (CSE)-induced transformation of bronchial epithelial cells into the cancerous phenotype and its mechanism of action. Herein, we exposed normal BEAS-2B cells for 8 days to varying concentrations of CSE or dimethylsulfoxide (DMSO), followed by a recovery period of 2 weeks. Next, the RBM5 protein was overexpressed in these transformed BEAS-2B cells though lentiviral infection. Later, the morphological changes, cell proliferation, cell cycle, apoptosis, invasion and migration were assessed. In addition, we analyzed the role of RBM5 in xenograft growth. The expression of RBM5 along with the genes related to cell cycle regulation, apoptosis and invasion were also examined. Finally, our results revealed that BEAS-2B cells exposed to 100 µg/ml CSE acquired phenotypic changes and formed tumors in nude mice, indicative of their cancerous transformation and had reduced RBM5 expression. Subsequent overexpression of RBM5 in these cells significantly inhibited their proliferation, induced G1/S arrest, triggered apoptosis and inhibited their invasion and migration, including xenograft growth. Thus, we established an in vitro model of CSE-induced cancerous transformation and concluded that RBM5 overexpression inhibited the growth of these transformed cells through cell cycle arrest and induction of apoptosis. Therefore, our study suggests the importance of RBM5 in the pathogenesis of smoking-related cancer.

Interluekin-35 in Asthma and Its Potential as an Effective Therapeutic Agent

Interleukin- (IL-) 35 is a member of the IL-12 cytokine family and a heterodimeric protein formed by Epstein-Barr-induced gene 3 (EBI3) and IL-12p35. Emerging evidence shows that IL-35 is a key player in the regulation of cellular communication, differentiation, and inflammation. Altered IL-35 expression has been found in disease conditions such as cancer, rheumatoid arthritis, and, more recently, asthma. In cancer, IL-35 is involved in the regulation of tumorigenesis, cancer progression, and metastasis. In rheumatoid arthritis, IL-35 acts as a negative regulator of inflammation. Similarly, IL-35 also appears to suppress allergic inflammation in asthma. In an in vivo murine model of asthma, transfer of adenovirus-mediated IL-35 markedly reduced the degree of airway hyperresponsiveness (AHR) and inflammatory cell infiltration. Many studies have shown the involvement of IL-35 in a number of aspects of allergic inflammation, such as eosinophil and neutrophil recruitment as well as inhibition of inflammatory mediators of the Th2 subtype. However, the exact molecular mechanisms underlying the role of IL-35 in human asthma have yet to be fully elucidated. This review describes the current evidence regarding the role of IL-35 in the pathophysiology of asthma and evaluates the potential of IL-35 as a biomarker for airway inflammation and a therapeutic target for the treatment of asthma.

Myricetin attenuates LPS-induced inflammation in RAW 264.7 macrophages and mouse models

AIM Acute lung injury is a common clinical syndrome associated with significant morbidity. Myricetin has been demonstrated to inhibit inflammation in a variety of diseases. In this study, we aimed to investigate the protective effects of myricetin on inflammation in lipopolysaccharide-stimulated RAW 264.7 cells and lipopolysaccharide-induced lung injury model. Results/methodology: In this study, we detected the anti-inflammatory effects of myricetin by ELISA, RT-PCR and Western blot, respectively. Myricetin significantly inhibited the production of the proinflammatory cytokines in vitro and in vivo. It exerted an anti-inflammatory effect through suppressing the NF-κB p65 and AKT activation in NF-κB pathway and JNK, p-ERK and p38 in MAPK signaling pathway. CONCLUSION Myricetin alleviated acute lung injury by inhibiting macrophage activation, and inhibited inflammation in vitro and in vivo. It may be a potential therapeutic candidate for the prevention of inflammatory diseases.

Expression of RNA-binding motif 10 is associated with advanced tumor stage and malignant behaviors of lung adenocarcinoma cancer cells

This study assessed RNA-binding motif 10 expression in lung adenocarcinoma tissues and examined the role and mechanism of RNA-binding motif 10 in the regulation of lung adenocarcinoma malignancy. Lung adenocarcinoma and corresponding adjacent non-tumor lung tissues from 41 patients were subjected to reverse transcription-polymerase chain reaction and Western blot assessment to detect RNA-binding motif 10 expression. Recombinant lentivirus carrying RNA-binding motif 10 complementary DNA was used to infect lung adenocarcinoma cell lines, A549 and H1299 cells. Complementary DNA microarray was used to profile RNA-binding motif 10–regulated genes. Levels of RNA-binding motif 10 messenger RNA and protein were significantly lower in lung adenocarcinoma tissues than those in paired non-tumor tissues (p < 0.001). Reduced RNA-binding motif 10 expression was found to be associated with an advanced tumor stage. RNA-binding motif 10 overexpression inhibited viability and colony formation capacity of lung adenocarcinoma cell lines and induced cell-cycle arrest at G0/G1 phase in A549 cells and at S phase in H1299 cells. Complementary DNA microarray analysis identified 304 upregulated and 386 downregulated genes induced by RNA-binding motif 10 overexpression, which may be involved in cancer, focal adhesion, peroxisome proliferator-activated receptor–regulated gene pathway, cytokine–cytokine receptor interaction, mitogen-activated protein kinase signaling, complement and coagulation cascades, platelet amyloid precursor protein pathway, extracellular matrix-receptor interaction, and small cell lung cancer–related genes. Expression of FGF2, EGFR, WNT5A, NF-κB, and RAP1A was downregulated, whereas expression of AKT2, BIRC3, and JUN was upregulated. RNA-binding motif 10 messenger RNA and protein were reduced in lung adenocarcinoma tissues, and RNA-binding motif 10 overexpression inhibited lung adenocarcinoma cancer cell malignant behavior in vitro. Molecularly, RNA-binding motif 10 regulates many gene pathways involving in the tumor development or progression.