Pulmonary Adenocarcinoma Cell Line A549 Research Articles

Effect of lentivirus-induced small interfering RNA targeted against toll-like receptor 3 on the proliferation and immune escape of human pulmonary adenocarcinoma cell line A549

Objective Toll-like receptors (TLR) are very important innate immunity molecules.Recently the relationship between TLR and human tumors had been gradually focused on by more and more researchers.This study was to investigate the effect of TLR3 on the cell proliferation,anti-apoptosis and immune escape in human pulmonary adenocarcinoma cells.Methods A549 cells were transfected with TLR3-RNA interference (RNAi) lentiviral vector,blank vector or non-transfected,then incubated with TLR3 ligand Poly (I∶ C).The expression of B7-H1,prostaglandin E synthase-2 (PGE-2) and phosphorylated p38 were respectively evaluated by flow cytometry,real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting.Cells apoptosis was detected by flow cytometry with Annexin V fluoresceine isothiocyanate (FITC)/propidium iodide (PI) double staining.Results Under the same time and concentration stimulation with Poly (I∶ C),the percentage of B7-H1-positive cells,the expression of PGE-2 mRNA and the relative percentage of phosphoryated p38 in TLR3-RNAi lentiviral vector transfected A549 cells were significantly lower than those in the non-transfected and blank vector transfected A549 cells (P ＜ 0.01).The percentage of the apoptotic cells in TLR3-RNAi lentiviral vector transfected A549 cells [(44.40 ± 1.41) ％] was significantly higher than that in the non-transfected [(34.70 ± 0.89) ％] and blank vector transfected [(36.50 ± 1.12) ％] A549 cells (P ＜ 0.01).Conclusion Down-regulation of TLR3 could inhibit the expression of B7-H1,PGE-2 and phosphorylated p38 in A549 cells,and weaken the anti-apoptosis ability of A549 cells. Key words: Lung cancer; Toll-like receptor 3; Apoptosis

Methyl protodioscin induces G2/M cell cycle arrest and apoptosis in A549 human lung cancer cells.

Background:Methyl protodioscin (MPD) is a furostanol bisglycoside with antitumor properties. It has been shown to reduce proliferation, cause cell cycle arrest.Objective:The present study elucidates the mechanism underlying MPD's apoptotic effects, using the A549 human lung cancer cell line.Materials and Methods:The human pulmonary adenocarcinoma cell line A549 was obtained from the Cell Bank of the Animal Experiment Center, North School Region, Sun Yat-Sen University. All of the cells were grown in RPMI 1640 supplemented with 10% fetal calf serum (Hyclone, Logan, UT, USA), penicillin (10,000 U/l), and streptomycin (100 mg/l) at 37°C in a 5% CO2 humidified atmosphere. The induction of apoptosis was observed in flow cytometry and fluorescent staining experiments.Results:MPD showed growth inhibitory effects in A549 cells in a dose- and time-dependent manner. The significant G2/M cell cycle arrest and apoptotic effect were also seen in A549 cells treated with MPD. MPD-induced apoptosis was accompanied by a significant reduction of mitochondrial membrane potential, release of mitochondrial cytochrome c to cytosol, activation of caspase-3, downregulation of Bcl-2, p-Bad, and upregulation of Bax.Conclusion:Our results show that the induction of apoptosis by MPD involves multiple molecular pathways and strongly suggest that Bcl-2 family proteins signaling pathways. In addition, mitochondrial membrane potential, mitochondrial cytochrome c and caspase-3 were also closely associated with MPD-induced apoptotic process in human A549 cells.

Effects of antidiabetic drug metformin on the migration and invasion abilities of human pulmonary adenocarcinoma A549 cell line in vitro.

There is growing evidence that metformin, a clinically widely used drug in the treatment of type II diabetes, may impede the growth of human tumors. However in a recent study it was found that metformin treatment might result in promotion of the angiogenic phenotype and promote early tumorigenic progression. In order to evaluate the relevance between metformin and tumor metastases, we investigated the effects of metformin on the migration and invasion abilities of human pulmonary adenocarcinoma cell line A549 in vitro and explored the possible underlying mechanisms. A549 cells were treated with 0.5 mmol/L, 2 mmol/L and 8 mmol/L metformin for 72h. The laterad-migration and invasion abilities of the cells in vitro were evaluated by scratch assay and Boyden-Chamber assay, respectively. Expressions of MMP2 and MMP9 mRNA of the cells before and after metformin treatment were measured by Real-Time PCR. The migration rate of A549 cells was increased after metformin treatment at the concentration of 8mmol/L. The invasion ability was also significantly increased from 37.4±4.6 to 59.8±7.2(P<0.05) by 8mmol/L metformin treatment. No significant difference of the migration and invasion abilities was observed between the Group 0.5mmol/L, 2mmol/L and the Control. The expressions of MMP2 and MMP9 mRNA were both up-regulated after metformin treatment, while in the 8mmol/L Group the genes changes were the most significant. Metformin can increase the migration speed and enhance invasion abilities of A549 cells in vitro, which may be attributed to the up-regulation of MMP2 and MMP9.

Enhancing Radiosensitivity of Human Pulmonary Adenocarcinoma Cell Line A549 by CpG ODN1826

Preclinical and early clinical trials indicate that synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG ODN) have potent immunostimulatory effects and can enhance the anticancer activity of a variety of cancer treatments. In this study, CpG ODN1826 was used to increase the radiosensitivity of human pulmonary adenocarcinoma cell line A549, and some underlying mechanisms were also detected. With the treatment of CpG ODN on A549 cells, there was an upregulation of CD40, CD80, CD86, and MHC-II on A549 cells in association with Th1 cytokine production. Further, the protein level of toll-like receptor (TLR)-4 was decreased, whereas TLR-9 was enhanced. Flow cytometry results showed that CpG ODN could increase mitochondrial membrane potential and subsequently promote the apoptosis of A549 cells, resulting in increased radiosensitivity. These results suggest a regulatory role of CpG ODN1826 in enhancing the radiosensitivity of A549 cells by activating the adaptive and innate immune responses, thereby providing a new potential strategy to the treatment of malignant tumors.

Empirical study on chemotherapeutic susceptibility of SP cells in human pulmonary adenocarcinoma cell line A549 in Vitro

Objective To explore the chemotherapeutic susceptibility of SP cells in human pulmonary adenocarcinoma cell line A549 and the possible mechanism of multidrug resistance

Inhibitory effect of low molecular weight heparin on the secretion of vascular endothelial growth factor by tumor cells in vitro

To investigate whether low molecular weight heparin (LMWH) may suppress the expression and secretion of vascular endothelial growth factor (VEGF) from tumor cells in vitro and inhibit the VEGF-induced proliferation of human tumor vascular endothelial cells. Human lung cancer cell line A549, human liver cancer cell line HepG2, human colon carcinoma cell lines HCT116 and HCT8 were used in this study. The expression levels of VEGF and TNF-alpha (tumor necrosis factor-alpha) in the tumor cells with or without pretreatment of LMWH/heparin were measured by standard sandwich ELISA technique. The VEGF mRNA level of HepG2 cells cultured with or without LMWH/heparin was determined by RT-PCR and real time PCR. Human umbilical vein endothelial cells (HUVEC) were cultured in tissue culture medium (TCM) with or without LMWH/heparin for 3 days. Then non-radioactive cell proliferation assay (MTS) kit and cell cycle assay by flow cytometry were performed to measure the proliferation of HUVEC. The VEGF levels in the control, LMWH, and heparin groups of the pulmonary adenocarcinoma cell line A549 were (1045.89 +/- 165.30) pg/ml, (782.45 +/- 67.17) pg/ml and (916.54 +/- 71.25) pg/ml, respectively. The VEGF levels in the control, LMWH, and heparin groups of the colon adenocarcinoma cell line HCT116 were (955.76 +/- 51.14) pg/ml, (822.89 +/- 142.39) pg/ml and (951.77 +/- 188.22) pg/ml, respectively. The VEGF levels in the control, LMWH, and heparin groups in the colon adenocarcinoma cell line HCT8 were (1290.62 +/- 41.23) pg/ml, (1063.34 +/- 63.82) pg/ml and (1257.14 +/- 11.40) pg/ml, respectively. The VEGF levels in the control, LMWH, and heparin groups in the liver cancer cell line HepG2 were (1083.00 +/- 134.35) pg/ml, (758.00 +/- 84.85) pg/ml and (874.00 +/- 22.62) pg/ml, respectively. The VEGF expression levels in the above mentioned cell lines cultured in TCM were significantly reduced in the LMWH-treated groups compared with that of the control group (P < 0.05). But the level of TNF-alpha in TCM-cultured cells was unaffected by LMWH. The VEGF mRNA was reduced in the LMWH-treated HepG2 cell line. Moreover, TCM exhibited stimulating effect on proliferation of HUVEC and the effect was significantly impaired by LMWH treatment. Flow cytometric analysis revealed that LMWH treatment arrested HUVECs at the G1 phase of cell cycle. LMWH can suppress the expression and secretion of VEGF by tumor cell lines and therefore have a potential inhibiting effect on angiogenesis induced by VEGF.

Aression of TLR9 in human pulmonary adenocarcinoma cell line A549

Objective Being considered as a bridge between the innate immunity and acquired immunity, Toll-like receptors (TRLs) are very important innate immunity moleculars. Recent researchs on the innate immunity have focused on the relationship between TLRs and human tumor. This paper investgated the expression and significance of TLR9 in human pulmonary adenocarcinoma cell (A549 cell) and human bronchial epithelial cell (HBE cell).

Fas Ligand Released by Activated Monocytes Causes Apoptosis of Lung Epithelial Cells in Human Acute Lung Injury Model in Vitro

Alveolar epithelial cell death plays a crucial role in the progression of acute lung injury. We have demonstrated up-regulation of Fas expression on alveolar epithelial cells, and soluble Fas ligand secretion from inflammatory cells upon acute lung injury. Here we show that the lipopolysaccharide-stimulated human monocyte cell line THP-1 releases Fas ligand, and that conditioned medium from lipopolysaccharide-stimulated THP-1 cells induces apoptosis of the human pulmonary adenocarcinoma cell line A549. Activation of caspase-3 and -8 is associated with the apoptosis. Gene targeting on Fas in A549 cells by specific small interfering RNA impairs apoptosis induced by conditioned medium from activated THP-1, while that on Fas ligand in THP-1 cells impairs the apoptosis-inducing activity of the conditioned medium produced by lipopolysaccharide-stimulated cells. These results suggest that Fas ligand released by monocytes causes alveolar epithelial cell death through a Fas-dependent apoptotic mechanism in the development of acute lung injury.

The modifier subunit of glutamate cysteine ligase (GCLM) is a molecular target for amelioration of cisplatin resistance in lung cancer

It is unclear whether a subunit of glutamate cysteine ligase [a modifier subunit (GCLM) and a catalytic subunit (GCLC)] is an effective target for ameliorating cisplatin (CDDP)-resistance. We inhibited each subunit of GCL mRNA using a specific ribozyme (M-Rz and C-Rz) in the pulmonary adenocarcinoma cell line A549. GCL activity was suppressed by the ribozyme. CDDP-resistance was more effectively ameliorated when GCLM rather than GCLC was inhibited. GCLM is a potentially more effective pharmacologic target for ameliorating CDDP-resistance in non-small cell lung cancer than GCLC.

Immunohistochemical analysis of human pulmonary carcinomas using monoclonal antibody 44-3A6

A monoclonal antibody, 44-3A6, was raised against the human pulmonary adenocarcinoma cell line A549. This antibody recognizes a protein antigen at the cell surface, which is preserved after formalin fixation and paraffin embedding. Immunohistochemical staining of lung tissue with this antibody revealed diffuse immunoreactivity of type II pneumocytes. Bronchial epithelial cells were also focally immunoreactive. Immunostaining of various bronchopulmonary carcinomas demonstrated characteristic patterns of reactivity. All of the 42 adenocarcinomas and 18 carcinoids were strongly immunoreactive either diffusely or focally. The immunoreaction occurred at the cell membrane and/or in the cytoplasm. None of the 39 squamous cell carcinomas, 12 bronchioloalveolar carcinomas, and 30 small cell neuroendocrine carcinomas was immunostained. Ten intermediate cell neuroendocrine carcinomas and 8 well-differentiated neuroendocrine carcinomas were relatively weakly immunoreactive, while 7 and 2 of them were negative. Six adenosquamous carcinomas were focally positive in glandular and "basaloid" areas, whereas squamous areas were negative. Twenty-one large cell carcinomas were focally immunoreactive, while 6 were negative. It appears that MCA 44-3A6 is an effective marker for certain features of "glandular" differentiation, which may be present even in tumors lacking obvious glands, and that it may be useful for the differential diagnosis of various bronchopulmonary carcinomas.