Low Dose Hyper-radiosensitivity in Human Lung Cancer Cell Line A549 and Its Possible Mechanisms

The low dose hyper-radiosensitivity （HRS） in human lung cancer cell line A549 was investigated, the changes of ATM kinase, cell cycle and apoptosis of cells at different doses of radiation were observed, and the possible mechanisms were discussed. A549 cells in logarithmic growth phase were irradiated with ^60Co y-rays at doses of 0-2 Gy. Together with flow cytometry for precise cell sorting, cell survival fraction was measured by means of conventional colony-formation assay. The expression of ATM1981 Ser-P protein was examined by Western blot 1 h after radiation. Apoptosis was detected by Hoechst 33258 fluorescent staining, and Annexin V-FITC/PI staining flow cytometry 24 h after radiation. Cell cycle distribution was observed by flow cytometry 6, 12 and 24 h after radiation. The results showed that the expression of ATM1981Ser-P protein was observed at 0.2 Gy, followed by an increase at 〉0.2 Gy, and reached the peak at 0.5 Gy, with little further increase as the dose exceeded 0.5 Gy. Twenty-four h after radiation, partial cells presented the characteristic morphological changes of apoptosis, and the cell apoptosis curve was coincident with the survival curve. As compared with control group, the cell cycle almost had no changes after exposure to 0.1 and 0.2 Gy radiation （P〉0.05）. After exposure to 0.3, 0.4 and 0.5 Gy radiation, G2/M phase arrest occurred 6 and 12 h after radiation （P〈0.05）, and the ratio of G2/M phase cells was decreased 24 h after radiation （P〈0.05）. It was concluded that A549 cells displayed the phenomenon of HRS/IRR. The mode of cell death was mainly apoptosis. The activity of ATM and cell cycle change may take an important role in HRS/IRR.

rmhTNF-α Combined with Cisplatin Inhibits Proliferation of A549 Cell Line In Vitro

Objective To explore the inhibitory effect of recombinant mutant human tumor necrosis factor-α(rmhTNF-α) in combination with cisplatin on human lung adenocarcinoma cell line A549. Methods Human lung adenocarcinoma cell line A549 was treated with varying concentrations of rmhTNF-α(0.38, 0.75, 1.50, 6.00 and 12.00 IU/ml) or cisplatin(3.91, 7.81, 15.63, 31.25 and 62.50 μg/ml) for 24 hours. Viable cell number was analyzed by using crystal violet staining. The inhibitory rates of A549 cells growth by the two drugs were calculated. For analyzing whether there was a synergistic effect of rmhTNF-α with cisplatin, A549 cells were treated with 0.75 IU/ml rmhTNF-α and increased concentrations of cisplatin. Results rmhTNF-α or cisplatin inhibited the growth of A549 cell lines in a dose-dependent manner. The inhibitory effect of rmhTNF-α combined with cisplatin was significantly greater than cisplatin alone at the same concentration(all P<0.01). Conclusion rmhTNF-α combined with cisplatin might have synergistic inhibitory effect on human lung adenocarcinoma cell line A549.

EXPRESSION AND REVERSION OF DRUG RESISTANCE-AND APOPTOSIS-RELATED GENES OF A DDP-RESISTANT LUNG ADENOCARCINOMA CELL LINE

Objective: To investigate the co-expression of drug resistance- and apoptosis-related genes of cisplatin (CDDP)-selected lung adenocarcinoma cell line A 549 DDP for compared to the parental cell line A549, and reverse of drug resistance by antisense s-oligodeoxynucleotides (S-ODNs) of differentially expressed genes. Methods: Sense and antisense S-ODN were transferred into A 549 DDP cells by lipofectin. The expression of drug resistance and apoptosis related genes was examined by RT-PCR, immunocytochemistry and flow cytometry, respectively. Apoptostic cells were identified by DNA electrophoresis and terminal deoxynucleotidyl transferase (TdT)-mediated biotin dUTP nick end-labeling(TUNEL). Drug resistance of tumor cells was detected by a cell viability (MTT) assay. Results: The expression of bcl-2 was positive and that of multidrug resistance-associated protein (MRP) at mRNA and protein level was increased in A 549 DDP compared to A549 cells. MDR1, c-myc and topoisomeras II (TOPO II) were similarly co-expressed in two cell lines. Both cell lines were negative for c-erbB-2 expression. In A 549 DDP cells, the expression of bcl-2 and MRP was significantly inhibited by their respective antisense S-ODNs. Antisense S-ODNs could also decrease significantly drug resistance of A 549 DDP cells to CDDP by promoting cell apoptosis. Conclusion: Both intrinsic and acquired drug resistance were involved in co-expression of multiple MDR-related genes in lung adenocarcinoma. Cooperation of bcl-2 and MRP genes appeared to play an important action to confer the resistance of A 549 DDP cells to CDDP. Their antisense S-ODNs are responsible for the decrease of drug resistance of this cell line by promoting apoptosis.

The effect of antisense oligodeoxynucleotides targeting Aurora A kinase on cell proliferation and chemosensitivity to paclitaxel in human lung cancer cell line A549

Objective： Aurora A kinase representing a family of evolutionadly conserved mitotic serine/threonine kinases has been found elevated in human lung adenocarcinoma cell line A549. It is suggested that the overexpression of Aurora A contributes to the carcinogenesis, chromosomal instability （CIN）, and de-differentiation of lung cancers. To address its possibility as a therapeutic target for lung cancer, we employed the antisense oligodeoxynucleotide （ASODN） technique to inhibit Aurora A expression and investigate its effects on tumor growth and cell cycle of A549, as well as the chemosensitivity to paclitaxel. Methods： Aurora AASODN was synthesized and transfected into A549 cells by lipofectAMINE 2000. Aurora A mRNA and protein expression were examined by reverse transcription-polymerase chain reaction （RT-PCR） and Western blot respectively. Cell cycle distribution was observed by flow cytometer. MTT assay was used to evaluate cell inhibition ratio before and after transfection. Results： The proliferation of the A549 cells was inhibited by Aurora A ASODN dose and time dependently. It was also observed that the IC50 of A549 cells after 48 hours＇ treatment of ASODN was about 300 nmol/L and under such circumstances, the Aurora A mRNA and protein expression significantly decreased （P 〈 0.05）, along with the induction of accumulation of cells in S phase and the G2-M transition. Furthermore, cell inhibition ratio of the combination of Aurora AASODN and paclitaxel was higher significantly than paclitaxel （P 〈 0.05） or Aurora AASODN alone （P 〈 0.05）. Conclusion： Inhibition of Aurora A expression can result in the suppression of cell growth and chemosensitizing activity to paclitaxel in human lung cancer cell line A549.

Empirical studies about quercetin increasing chemosensitivity on human lung adenocarcinoma cell line A549

Objective： The present study was designed to investigate whether quercetin exerts increasing chemosensitivity on human lung adenocarcinoma cells when quercetin combined with cisplatin （DDP） and vincristine （VCR） in vitro respectively and its possible antitumor mechanism. To provide experimental proof for clinical combination application. Methods： Using intermittent administration of high dose VCR, human lung adenocarcinoma sensitive cell line （A549/S） was induced to VCR- resistant human lung adenocarcinoma cell line （A549NCR）. MTT assay was adapted for examing the 50% inhibition （IC50） value of DDP and VCR on A549/S and A549/VCR when quercetin combined with DDP and VCR respectively. Results： IC50 of DDP on A549/S and A549/VCR was 10.18 and 12.35 mg/L, and the IC50 of VCR on the two cell lines was 1.21 and 12.77 rag/L, respectively. The resistance fold of A549/VCR on VCR and DDP was 10.55 and 121, respectively. When quercetin at concentration of 50, 100 and 200 pmol/L in combination with DDP and VCR respectively, the IC50 of DDP and VCR on A549/S and A549/VCR were obvious decreased （P 〈 0.05 - P 〈 0.01）. Conclusion： The experiment results suggested that quercetin could increase the chemosensitivity and partly revise the resistance of A549NCR.

Enhanced cytotoxic effect on human lung carcinoma cell line(A549) by gold nanoparticles synthesized from Justicia adhatoda leaf extract

Objective: To synthesize bio-inspired gold nanoparticles(AuNPs) using the leaf extract of Justicia adhatoda and evaluate the anti-cancer activity on human lung cancer cell line(A549).Methods: Synthesis of AuNPs was done using an aqueous leaf extract of Justicia adhatoda as a green route. The bio-synthesized AuNPs were confirmed and characterized by using various spectral studies such as UV-Vis spectrum, Scanning Electron Microscope with EDAX, Transmission Electron Microscope, Fourier Transmission Infrared Spectroscope analysis and Surface Enhanced Raman Spectroscopy. The cell viability was determined by MTT reduction assay. In addition, cytomorphology and the nuclear morphological study of A549 cell line was observed under fluorescence microscope. Results: UV-Vis spectrum showed surface plasmon resonance peak at 547 nm, scanning electron microscope and transmission electron microscope studies showed the monodispersed spherical shape and its average size in the range of 40.1 nm was noticed. Fourier Transmission Infrared Spectroscope analysis confirmed that the C=O group of amino acids of proteins had strong ability to bind with the surface of nanoparticle. Interestingly, our results also demonstrated inhibited proliferation of A549 cell line by MTT(IC50 value: 80 μg/mL). Cell morphology was observed and cell death was caused by apoptosis as revealed by propidium iodide staining. Conclusions: The current study proves the anticancer potential of bio-synthesized AuNPs. Thus, synthesized AuNPs can be used for the treatment of human lung cancer cell(A549) and it can be exploited for drug delivery in future.

TIME-AND DOSE-DEPENDENT UP-REGULATION OF TNF-α mRNA AFTER IRRADIATION OF HUMAN NSCLC CELL LINES IN VITRO

Objective： Even though radiotherapy plays a major role in the local treatment of non-small cell lung cancer （NSCLC）, little is known about the molecular effects of irradiation in this tumor. In the present study, we examined two NSCLC cell lines for their endogenous production of TNF-α after irradiation. To investigate the radiation-induced TNF-α production in NSCLC cell lines. Methods： Two human NSCLC cell lines （A549： squamous; NCI-H596： adenosquamous） were investigated for their TNF-α mRNA （real-time RT-PCR） after exposure to different irradiation doses （2, 5, 10, 20, 30, 40 Gy） and time intervals （1, 3, 6, 12, 24, 48 or 72 h）. The TNF-α mRNA expression was quantified by real-time RT-PCR. The clonogenic survival was evaluated after irradiation with 2, 4, 6 and 8 Gy. Results： Non-irradiated NSCLC cells exhibited no or very low TNF-α expression. For the NCI-H596 cell line, TNF-α expression was significantly elevated 1～12 h （maximum 6h： 568fold increase relative to unirradiated cells） in a time-dependent manner. The radiation-induced increase could be observed after irradiation with 2 Gy reaching maximal at 40 Gy, with 83 times higher than normal controls. The clonogenic survival of these cell lines was nearly identical. Conclusion： NCI-H596 cells produce significant quantities of TNF-α following irradiation in a time- and dose-dependent manner. The pro-inflammatory cytokine TNF-α is a key mediator for the pathogenesis of radiation pneumonitis. Radiation-induced endogenous TNF-α expression in NSCLC cells may affect the normal lung adjacent to the tumor and may be associated with an adverse clinical outcome of the patient.

The Inhibitory Effects of Rh-endostatin(YH-16) in Combination with Radiotherapy on Lung Adenocarcinoma A549 in Mice and the Underlying Mechanisms

In order to investigate the inhibitory effects of Endostar(rh-endostatin,YH-16)in combination with radiotherapy on lung adenocarcinoma A549 in mice and the interaction mechanisms of combined therapy,the transplantation tumor models of A549 lung adenocarcinoma were established.When the largest diameter of tumor reached 1.0cm,all nude mice were randomly divided into 4 groups:Endostar group,radiotherapy group,radiotherapy plus Endostar(combined treatment)group,and control group(n=6 in each group).The largest d...

Study of ATP borate ester effects on cell sensitization to radiation emitted by a nuclear reactor

Adenosine triphosphate(ATP)borate ester as a new boron agent for boron neutron capture therapy was tested.It was synthesized via a dehydration reaction induced by heating adenosine triphosphate disodium with boric acid.Next,ATP borate ester pretreatments were assessed to study their effects on cell sensitization from exposure to thermal neutron irradiation emitted by a nuclear reactor.Using cell viability assays(CCK8),survival rates of A549 cells pretreated with or without boroncontaining agents,including ATP borate ester and 4-dihydroxyborylphenylalanine(BPA),were measured.One week after feeding an ATP borate ester solution to tumorbearing nude mice,elemental B content values of tumor muscle and blood were measured using inductively coupled plasma mass spectrometry(ICP-MS).Meanwhile,other tumor tissue samples were placed in a culture medium,subjected to a 3-min neutron irradiation exposure,and then fixed in formalin 24 h later for the terminaldeoxynucleotidyl transferase(TDT)-mediated d UTP nick end labeling(TUNEL)immunohistochemical staining analysis.Results showed that A549 cell irradiation sensitization(irradiation dose of 0.33 Gy)varied with pretreatment.Sensitization values of the ATP borate ester pretreatment group were 1.3–14.1 with boron agent concentrations of 0.3–4.5 mM.Within 1.1–3.4 mM,ATP borate ester showed significantly higher sensitization values than BPA.Meanwhile,TUNEL results demonstrated that apoptosis rates of tumor tissue cells exposed to irradiation after ATP borate ester pretreatment significantly exceeded the corresponding rates for BPA-pretreated cells.In animal experiments,although the distribution ratio of ATP borate ester(tumor tissue/normal muscle,T/N)of 1.2 was not significantly different compared with that of BPA(1.3),the total ATP borate ester concentration in the tumor tissue(0.79±0.05μg/g)significantly exceeded that of BPA(0.58±0.05μg/g).Thus,compared with BPA,the greater enrichment of ATP borate ester in tumor tissues permits preferential targeting toward tumor cells for radiation sensitization.Therefore,ATP borate ester is superior to BPA for use in boron neutron capture therapy.

Reversal effect of recombinant human Endostatin on cisplatin resistance in A549/DDP human lung adenocarcinoma cells in vitro

Objective： Recombinant human Endostatin （rh-Endostatin, YH-16） can reverse cisplatin resistance in A549/DDP cells. However, the possible effect of rh-Endostatin in reversing DDP-resistance in A549/DDP cells and the mechanism are needed to be investigated. Methods： Lung adenocarcinoma cell line A549 and its DDP-resistant cell line A549/DDP were treated with DDP and/or recombinant human Endostatin. Difference in drug resistance was analyzed between different regi- mens and between different cell lines after a 72 h-treatment in vitro. And below the non-cytotoxic concentration of rh-End- ostatin, the possibility of rh-Endostatin in reversing DDP-resistance in A549/DDP was evaluated. The resistance protein which was detected in the study included P glycoprotein （P-gp） and topoisomerase II （Topo-II）. Results： Rh-Endostatin below 400 IJg/mL showed no cytotoxicity in either A549 or A549/DDP after 72 h-treatment with it. The inhibited concentration of 50% （IC50） observed for DDP was （0.79 _＋ 0.05） IJg/mL in A549 and （13.2 ＋ 1.1） in A549/DDP respectively. IC50 was reduced to 2.57 ＋ 0.05 #g/mL in A549/DDP treated by rh-Endostatin below the non-cytotoxic concentrations in combination with DDP, with a reversal fold （RF） of 5.14 and a relative reversal rate of 85.6%. Apoptotic rates were 2.01%, 13.47% and 29.26% re- spectively for cells treated with rh-Endostain, DDP, and the combination. The rate of the A549/DDP control group was 0.99%. The expression level of P-gp or Topo-II was higher in A549/DDP cells than in A549 cells. Rh-Endostatin may partially reverse DDP-resistance in A549/DDP cells in vitro, with a probable mechanism related to lowering expression of P-gp and Topo-II. Conclusien： Rh-Endostatin of non-cytotoxic dose partially reversed cisptatin resistance in cisplatin-resistant human lung adenocarcinoma cell line A549/DDP. Rh-Endostatin reversed the resistance of A549/DDP cells to DDP, which may be related to decreased protein expression of P-gp and Topo-II in A549/DDP cells.

Anti-angiogenesis effect of Demethyl bryoanthrathiophene(DBT) in vitro

Objective:The aim of the study was to investigate the effect of Demethyl bryoanthrathiophene(DBT) on proliferations of human umbilical vein endothelial cells(HUVECs) and human lung adenocarcinoma cell line A549,and antiangiogenic effect of DBT on HUVECs in vitro.Methods:MTT assay was used to observe the effect of DBT on proliferations of HUVECs and A549 cells,flat plate scarification assay and tube formation in vitro test were used to observe the impact of DBT on migration and vaso-formed ability of HUVECs.The effects of DBT on apoptosis and cell cycle of HUVECs were calculated by flow cytometry.Results:MTT assay showed that treatment with DBT resulted in strong inhibition to the growth of HUVECs and A549 cells.The inhibition effects of DBT on HUVECs and A549 cells were related to dosage and times of dependency.In different doses of DBT(0.16,0.32 and 0.48 μmol/L) of flat plate scarification for 24 h,inhibition rates of DBT to migration of HUVECs were 14.70%,38.23% and 58.82%,respectively.In dose of DBT from 0.04,0.20 to 0.40 μmol/L for 24 h in tube formation,there were significance differences(P < 0.01) in the decreasing number of angiogenesis and incomplete blood vessel compared with control groups.All results showed that DBT promoted the apoptosis rate of HUVECs,and the increase of concentration of DBT accompanied the acceleration of apoptosis rate.Conclusion:DBT could inhibit the proliferations of HUVECs and A549 cells,and effectively suppress angiogenesis in vitro.

Microwave induces apoptosis in A549 human lung carcinoma cell line

Background Microwaves have other biological effects on cancer as well besides killing tumor cells by coagulation.Some studies showed that microwaves may induce apoptosis in some tumor cells. The apoptotic effect of microwaves may help in clinic to remove residual malignant cells nearby the primary lesion and avoid relapse subsequently. However,there is little evidence on this subject from lung cancer. We studied the effect of microwaves on inducing apoptosis in the human lung carcinoma cell line A549 cells, aiming to identify its effect on apoptosis.Methods A549 cells were radiated by various intensities and durations of microwaves. Apoptosis induction in A549 cells was analyzed by morphological observations, tetrazolium blue color method （MTT） assays, flow cytometery,immunohistochemistry, and image analyses.Results Morphological changes in A549 cells, including cell shrinking and nuclear pycnosis, were observed after microwave radiation. Microwaves significantly inhibited metabolic activities and induced apoptosis in A549 cells. The results of the MTT assay showed a significant decrease of cell activities in all the radiation groups compared with the normal control （P ＜0.01）. The low point of cell activities often appeared at 6-12 hours after radiation. Apoptosis was also confirmed by flow cytometery. The early stage apoptotic rate reached 6.10%-17.98% and the advanced stage apoptotic rate ＋ necrosis rate reached 8.04%-44.06% at 6 hours after microwave irradiation, in contrast to 2.32% and 4.10% in the respective control groups. Down-regulation of Bcl-2 expression and up-regulation of p53 expression were observed by immunohistochemistry after radiation. In most treated groups, the down-regulation of Bcl-2 expression reached its lowest level at 3-6 hours after radiation （integrated optical density （IOD）-6 hours： 2.13±0.08-5.14±0.13 vs. control： 5.79±0.10, P＜0.01 ） and the up-regulation of P53 expression peaked at about 3 hours （IOD-3 hours： 2.61±0.13-8.07±0.11 vs. control：1.29±0.07, P ＜0.01）. Cell damage, apoptosis, and protein expression levels in the samples differed depending on the radiation intensity and duration.Conclusions Microwaves can promote apoptosis in A549 cells. The effect depends on the duration and dosage of microwave radiation. Bcl-2 and p53 proteins may be involved in the apoptotic process of A549 cells induced by microwaves.

THE EFFECTS OF THE ETHANOLIC FRACTION OF CORIOLUS VERSICOLOR ON THE A549 NON-SMALL-CELL LUNG CANCER CELL LINE

Coriolus versicolor has demonstrated anti-cancer effects via polysaccharide-peptides(PSP)and polysaccharide Krestin(PSK).However,many other bioactive compounds within Coriolus versicolor(CV)may not have been identified.Our primary focus was to determine whether the ethanolic extract of Coriolus versicolor demonstrated any anti-cancer effects.The crude ethanolic extract was utilized,as was

Agglutinin isolated from Arisema heterophyllum Blume induces apoptosis and autophagy in A549 cells through inhibiting PI3K/Akt pathway and inducing ER stress

Arisaema heterophyllum Blume is one of the three medicinal plants known as traditional Chinese medicine Rhizoma Arisaematis(RA). RA has been popularly used to treat patients with convulsions, inflammation, and cancer for a long time. However, the underlying mechanisms for RA effects are still unclear. The present study was designed to determine the cytotoxicity of agglutinin isolated from Arisema heterophyllum Blume(AHA) and explore the possible mechanisms in human non-small-cell lung cancer A549 cells. AHA with purity up to 95% was isolated and purified from Arisaema heterophyllum Blume using hydrophobic interaction chromatography. AHA dose-dependently inhibited the proliferation of A549 cells and induced G_1 phase cell cycle arrest. AHA induced apoptosis by up-regulating pro-apoptotic Bax, decreasing anti-apoptotic Bcl-2, and activating caspase-9 and caspase-3. In A549 cells treated with AHA, the PI3K/Akt pathway was inhibited. Furthermore, AHA induced increase in the levels of ER stress markers such as phosphorylated eukaryotic initiation factor 2α(p-eIF2α), C/EBP-homologous protein(CHOP), inositol-requiring enzyme 1α(IRE1α), and phosphorylated c-Jun NH_2-terminal kinase(p-JNK). AHA also induced autophagy in A549 cells. Staining of acidic vesicular organelles(AVOs) and increase in the levels of LC3II and ATG7 were observed in AHA-treated cells. These findings suggested that AHA might be one of the active components with anti-cancer effects in Arisaema heterophyllum Blume. In conclusion, cytotoxicity of AHA on cancer cells might be related to its effects on apoptosis and autophagy through inhibition of PI3K/Akt pathway and induction of ER stress.

TGF-β/Akt/Smad signaling regulates ionizing radiation-induced epithelial-mesenchymal transition in acquired radioresistant lung cancer cells

Objective:To define the properties of lung cancer cells that resisted conventionally fractionated radiation exposure.Methods:Acquired radioresistant lung cancer cell line A549 was constructed by X-ray irradiation with a clinical conventional fraction dose of 2 Gy daily during 30 fractions.Cell morphology,molecular markers,migration capacity and invasion potential were evaluated by the microscope,Western blot,immunofluorescence,wound healing test and transwell chamber assay,respectively.Results:Radioresistant A549 cells shifted from an epithelial to a mesenchymal morphology,termed as epithelial-mesenchymal transition(EMT),and was accompanied by decreased expressions of epithelial markers(F=4.568,P<0.05)and increased expression of mesenchymal markers(F=4.270,P<0.05),greater migratory and invasive capabilities(t=6.386,5.644,P<0.05).The expression of TGF-β,and phosphorylated levels of Akt and Smad3 were also enhanced(F=6.496,4.685,3.370,P<0.05).Furthermore,the EMT phenotype induced by radiation could be reversed through inhibition of TGF-β,Akt or Smad3,indicating a functional relationship be-tween them.Conclusions:EMT mediates acquired radioresistance of lung cancer cells induced by IR with clinical parameters,and the crosstalk mode of TGF-β/Akt/Smad signaling plays a critical regulatory role in this process.