Knockdown of DEAD-box 51 inhibits tumor growth of esophageal squamous cell carcinoma via the PI3K/AKT pathway.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent malignancies that seriously threaten people's health worldwide. DEAD-box helicase 51 (DDX51) is a member of the DEAD-box (DDX) RNA helicase family, and drives or inhibits tumor progression in multiple cancer types. AIM: To determine whether DDX51 affects the biological behavior of ESCC. METHODS: The expression of DDX51 in ESCC tumor tissues and adjacent normal tissues was detected by Immunohistochemistry (IHC) analyses and quantitative PCR (qPCR). We knocked down DDX51 in ESCC cell lines by using a small interfering RNA (siRNA) transfection. The proliferation, apoptosis, and mobility of DDX51 siRNA-transfected cells were detected. The effect of DDX51 on the phosphoinositide 3-kinase (PI3K)/AKT pathway was investigated by western blot analysis. A mouse xenograft model was established to investigate the effects of DDX51 knockdown on ESCC tumor growth. RESULTS: DDX51 exhibited high expression in ESCC tissues compared with normal tissues and represented a poor prognosis in patients with ESCC. Knockdown of DDX51 induced inhibition of ESCC cell proliferation and promoted apoptosis. Moreover, DDX51 siRNA-expressing cells also exhibited lower migration and invasion rates. Investigations into the underlying mechanisms suggested that DDX51 knockdown induced inactivation of the PI3K/AKT pathway, including decreased phosphorylation levels of phosphate and tensin homolog, PI3K, AKT, and mammalian target of rapamycin. Rescue experiments demonstrated that the AKT activator insulin-like growth factor 1 could reverse the inhibitory effects of DDX51 on ESCC malignant development. Finally, we injected DDX51 siRNA-transfected TE-1 cells into an animal model, which resulted in slower tumor growth. CONCLUSION: Our study suggests for the first time that DDX51 promotes cancer cell proliferation by regulating the PI3K/AKT pathway; thus, DDX51 might be a therapeutic target for ESCC.

Effect of spleen tyrosine kinase on nonsmall cell lung cancer.

AIM OF STUDY: To investigate the anti.tumor effect of spleen tyrosine kinase. (Syk) on the human nonsmall cell lung cancer cells in vitro and its mechanism. MATERIALS AND METHODS: In this study, we constructed a eukaryotic expression vector pcDNA3.1D/V5-His-TOPO/Syk and transfected it into human nonsmall cell lung cancer cells A549. Then, we not only analyzed the expression of Syk in transfected cells and its invasion but also the expression of matrix metalloproteinase-9 (MMP-9). RESULTS: The results showed that overexpressed Syk significantly inhibited A549 cell invasive ability by decreasing the expression of MMP-9. CONCLUSION: The overexpressed Syk plays an important role in tumor invasion and metastasis, and a negative role in human nonsmall cell lung cancer cells.

Inhibitory effects of syk transfection on lung cancer cell invasion.

OBJECTIVE: Spleen tyrosine kinase (Syk) is closely related to tumor invasion and metastasis, and has been shown to have potential inhibitory effects in tumors. In this study, we constructed a eukaryotic expression vector for Syk and analyzed its effects on invasive ability of the A549 non-small cell lung cancer cell line in vitro. METHODS: A fragment of Syk was obtained by RT-PCR from human lung cancer cells and cloned into the expression vector pLNCXSyk. After restriction endonuclease digestion, PCR and DNA sequencing confirmation, the recombinant Syk expression plasmid was transfected into A549 human lung cancer cells using lipofectamine protocols. After selection, the cells stably expressed Syk. Detection of Syk expression of the cells by RT-PCR, and invasive ability were examined. RESULTS: The eukaryotic expression plamid pLNCXSyk was constructed and expressed stably in the A549 human lung cancer cells. The RT-PCR results showed that Syk mRNA expression was upregulated significantly (P<0.05). Lower invasion through a basal membrane were apparent after transfection (P<0.05). CONCLUSIONS: A eukaryotic expression plasmid to cause Syk expression in lung cancer cells can obviously inhibit their invasive ability in vitro.

[Study of the expression and function of Syk and VEGF-C in the development of non-small cell lung cancer].

OBJECTIVE: To explore the role of Syk and VEGF-C in the development of NSCLC. METHODS: Transfered these genes(eukaryotic expression vector pcDNA3.1-VEGF-C and pLNCX-syk)into A549 cells with the liposomes. Tested the expression of VEGF-C mRNA and Syk mRNA with RT-PCR.Investigated the cell invasion assay with transwell chamber in vitro. Analysis the expression of VEGF-C proteins in A549 cells and detect Syk and VEGF-C proteins of 81 NSCLC tissue samples with immunohistochemical staining. RESULTS: Higher expression of VEGF-C was revealed in VEGF-C-construct-transfected A549 cell than that in controls through RT-PCR (P < 0.05) and immunohistochemistry(P < 0.01).RT-PCR also revealed that Syk expression was higher in Syk-construct-transfected cells than in controls (P < 0.05). The cell invading experiments showed that there was more invaded cells in both transfected terms than in controls (P < 0.05). The expression of Syk protein in NSCLC tissue were significantly lower than that in the normal lung tissue (P < 0.05), while the expression of VEGF-C protein in NSCLC tissue were significantly higher than that in the normal lung tissue(P < 0.05). The expression of Syk and VEGF-C has a negative correlationship (r = -1.000, P = 0.019). CONCLUSION: The expression of Syk and VEGF-C has a negative correlationship in NSCLC tissue, VEGF-C-construct-transfected A549 cells are more aggressive than Syk-construct-transfected cells. And they may cooperated with each other in the development of NSCLC.

[Inhibitory effects of ODC and AdoMetDC bi-antisense virus on the growth and invasion of lung cancer cell A-549].

OBJECTIVE: To study the inhibitory effects of antisense bicistronic recombinant adenovirus vector of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (Ad-ODC-AdoMetDCas) on polyamine biosynthesis,proliferation and invasion of lung cancer cells. METHODS: Adenovirus-mediated gene transduction efficiency was assessed with counting GFP-positive cells using trypan blue. Western Blot and HPLC were used to detect ODC and S-AdoMetDC expression and polyamine content in A-549 cells respectively. Viable cell counting and cell cycle analysis were adopted to evaluate cell growth and cell cycle distribution, and A-549 cell invasion in vitro was detected with Matrigel invasion assay. RESULTS: Approximate 75% of A-549 cells were infected with Ad-ODC-AdoMetDCas when multiplicity of infection reached 50. Our study demonstrated that Ad-ODC-AdoMetDCas vector-mediated gene transfer inhibited tumor cell growth through the blockade of polyamine synthesis pathway. The tumor cells were arrested at cell cycle G1 phase after gene transfer. Gene transferred tumor cells were shown to possess markedly decreased invasiveness. CONCLUSION: Ad-ODC-AdoMetDCas has significant inhibitory effects on lung cancer cell proliferation and invasion and bears therapeutic potential for the treatment of lung cancer.