OBJECTIVETo investigate the effect of curcumin (Cur) on radiosensitivity of nasopharyngeal carcinoma cell CNE-2 and its mechanism.

METHODThe effect of curcumin on radiosensitivity was determined by the clone formation assay. The cell survival curve was fitted by Graph prism 6. 0. The changes in cell cycle were analyzed by flow cytometry (FCM). The differential expression of long non-coding RNA was detected by gene chip technology. Part of differentially expressed genes was verified by Real-time PCR.

RESULTAfter 10 micro mol L-1 Cur had worked for 24 h, its sensitization enhancement ratio was 1. 03, indicating that low concentration of curcumin could increase the radiosensitivity of nasopharyngeal carcinoma cells; FCM displayed a significant increase of G2 phase cells and significant decrease of S phase cells in the Cur combined radiation group. In the Cur group, the GUCY2GP, H2BFXP, LINC00623 IncRNA were significantly up-regulated and ZRANB2-AS2 LOC100506835, FLJ36000 IncRNA were significantly down-regulated.

CONCLUSIONCur has radiosensitizing effect on human nasopharyngeal carcinoma CNE-2 cells. Its mechanism may be related to the changes in the cell cycle distribution and the expression of long non-coding IncRNA.

Cell Cycle ; drug effects ; radiation effects ; Cell Line, Tumor ; Cell Survival ; drug effects ; radiation effects ; Curcumin ; pharmacology ; Gene Expression Regulation, Neoplastic ; drug effects ; radiation effects ; Humans ; RNA, Long Noncoding ; genetics ; Radiation Tolerance ; drug effects

Reduced radiosensitivity of lung cancer cells represents a pivotal obstacle in clinical oncology. The hypoxia-inducible factor (HIF)-1α plays a crucial role in radiosensitivity, but the detailed mechanisms remain elusive. A relationship has been suggested to exist between hypoxia and autophagy recently. In the current study, we studied the effect of hypoxia-induced autophagy on radioresistance in lung cancer cell lines. A549 and H1299 cells were cultured under normoxia or hypoxia, followed by irradiation at dosage ranging from 0 to 8 Gy. Clonogenic assay was performed to calculate surviving fraction. EGFP-LC3 plasmid was stably transfected into cells to monitor autophagic processes. Western blotting was used to evaluate the protein expression levels of HIF-1α, c-Jun, phosphorylated c-Jun, Beclin 1, LC3 and p62. The mRNA levels of Beclin 1 were detected by qRT-PCR. We found that under hypoxia, both A549 and H1299 cells were radio-resistant compared with normoxia. Hypoxia-induced elevated HIF-1α protein expression preferentially triggered autophagy, accompanied by LC3 induction, EGFP-LC3 puncta and p62 degradation. In the meantime, HIF-1α increased downstream c-Jun phosphorylation, which in turn upregulated Beclin 1 mRNA and protein expression. The upregulation of Beclin 1 expression, instead of HIF-1α, could be blocked by SP600125 (a specific inhibitor of c-Jun NH2-terminal kinase), followed by suppression of autophagy. Under hypoxia, combined treatment of irradiation and chloroquine (a potent autophagy inhibitor) significantly decreased the survival potential of lung cancer cells in vitro and in vivo. In conclusion, hypoxia-induced autophagy through evaluating Beclin1 expression may be considered as a target to reverse the radioresistance in cancer cells.
Animals ; Apoptosis Regulatory Proteins ; genetics ; metabolism ; Autophagy ; Beclin-1 ; Cell Hypoxia ; Cell Line, Tumor ; Cell Survival ; genetics ; radiation effects ; Gene Expression Regulation, Neoplastic ; radiation effects ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Immunoblotting ; Lung Neoplasms ; genetics ; metabolism ; pathology ; Membrane Proteins ; genetics ; metabolism ; Mice, Nude ; Microscopy, Fluorescence ; Microtubule-Associated Proteins ; genetics ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-jun ; metabolism ; Radiation Tolerance ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Transplantation, Heterologous ; Tumor Burden ; genetics

AIM: Radiation induces an important apoptosis response in irradiated organs. The objective of this study was to investigate the radioprotective effect of tetramethylpyrazine (TMP) on irradiated lymphocytes and discover the possible mechanism of protection. METHOD: Lymphocytes were pretreated for 12 h with TMP (25-200 μmol·L(-1)) and then exposed to 4 Gy radiation. Cell apoptosis and the signaling pathway were analyzed. RESULTS: Irradiation increased cell death, DNA fragmentation, activated caspase activation and cytochrome c translocation, downregulated B-cell lymphoma 2 (Bcl-2) and up-regulated Bcl-2-associated X protein (Bax). Pretreated with TMP significantly reversed this tendency. Several anti-apoptotic characteristics of TMP, including the ability to increase cell viability, inhibit caspase-9 activation, and upregulate Bcl-2 and down-regulate Bax in 4Gy-irradiated lymphocytes were determined. Signal pathway analysis showed TMP could translate nuclear factor-κB (NF-κB) from cytosol into the nucleus. CONCLUSION The results suggest that TMP had a radioprotective effect through the NF-κB pathway to inhibit apoptosis, and it may be an effective candidate for treating radiation diseases associated with cell apoptosis.
Apoptosis ; drug effects ; radiation effects ; Cell Line ; Cell Survival ; drug effects ; radiation effects ; DNA Fragmentation ; drug effects ; radiation effects ; Drugs, Chinese Herbal ; pharmacology ; Humans ; Lymphocytes ; cytology ; drug effects ; radiation effects ; NF-kappa B ; genetics ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; Pyrazines ; pharmacology ; Radiation-Protective Agents ; pharmacology ; bcl-2-Associated X Protein ; genetics ; metabolism

This study explored the role of radiation-induced autophagy in low-dose hyperradiosensitivity (HRS) in the human lung cancer cell line A549. A549 cells, either treated with an autophagic inhibitor 3-methyladenine (3-MA), or with a vehicle control, were irradiated at different low doses (≤0.5 Gy). The generation of autophagy was examined by laser scanning confocal microscopy. Western blotting was used to detect the expression of microtubule-associated protein l light chain 3B II (LC3B-II). Flow cytometry (FCM) and clonogenic assays were used to measure the fraction of surviving cells at the low irradiation doses. Our results showed that there was a greater inhibition of autophagic activity, but a higher degree of low-dose HRS in A549 cells treated with 3-MA than in control group. Our data demonstrated that radiation-induced autophagy is correlated with HRS in A549 cells, and is probably one of the mechanisms underlying HRS.
Adenine ; analogs & derivatives ; pharmacology ; Autophagy ; drug effects ; radiation effects ; Blotting, Western ; Cell Line, Tumor ; Cell Survival ; drug effects ; radiation effects ; Dose-Response Relationship, Radiation ; Flow Cytometry ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Lung Neoplasms ; genetics ; metabolism ; pathology ; Microscopy, Confocal ; Microscopy, Electron, Transmission ; Microtubule-Associated Proteins ; genetics ; metabolism ; Phagosomes ; drug effects ; radiation effects ; ultrastructure ; Radiation Tolerance ; drug effects ; radiation effects

AIM: To investigate the radioprotective effect of adenine on irradiated lymphocytes and discover the possible mechanisms of protection. METHODS: Lymphocytes were pretreated for 12 h with adenine (0.001-0.1 μmol·L(-1)) and then exposed to 4 Gy radiation. Cell viability was observed by the MTS assay, apoptosis was detected by Annexin V-FITC/PI, DNA ladder, and caspase 3/7 activity. Caspase-9, Bax, and Bcl-2 gene expression was investigated by RT-PCR. RESULTS: Irradiation increased cell death and DNA fragmentation. Pretreatment with adenine significantly reversed this tendency. Furthermore, several anti-apoptotic characteristics of adenine were determined, including the ability to inhibit caspase 3/7, upregulate B-cell lymphoma (Bcl-2) and downregulate Bcl-2- associated X (Bax), capase-9 gene expression in 4 Gy-irradiated AHH-1 cells. CONCLUSION The results suggest that adenine had a radioprotective effect to inhibit apoptosis in a concentration dependent manner.
Adenine ; pharmacology ; Apoptosis ; drug effects ; radiation effects ; Caspase 9 ; genetics ; metabolism ; Cell Line ; Cell Survival ; drug effects ; radiation effects ; Gamma Rays ; Gene Expression ; drug effects ; radiation effects ; Humans ; Lymphocytes ; drug effects ; radiation effects ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; Radiation-Protective Agents ; pharmacology ; bcl-2-Associated X Protein ; genetics ; metabolism

Ascaris suum eggs are inactivated by composting conditions; however, it is difficult to find functional changes in heat-treated A. suum eggs. Here, unembryonated A. suum eggs were incubated at 20degrees C, 50degrees C, and 70degrees C in vitro, and the gene expression levels related to viability, such as eukaryotic translation initiation factor 4E (IF4E), phosphofructokinase 1 (PFK1), and thioredoxin 1 (TRX1), and to apoptosis, such as apoptosis-inducing factor 1 (AIF1) and cell death protein 6 (CDP6), were evaluated by real-time quantitative RT-PCR. No prominent morphological alterations were noted in the eggs at 20degrees C until day 10. In contrast, the eggs developed rapidly, and embryonated eggs and hatched larvae began to die, starting on day 2 at 50degrees C and day 1 at 70degrees C. At 20degrees C, IF4E, PFK1, and TRX1 mRNA expression was significantly increased from days 2-4; however, AIF1 and CDP6 mRNA expression was not changed significantly. IF4E, PFK1, and TRX1 mRNA expression was markedly decreased from day 2 at 50degrees C and 70degrees C, whereas AIF1 and CDP6 mRNA expression was significantly increased. The expressions of HSP70 and HSP90 were detected for 9-10 days at 20degrees C, for 3-5 days at 50degrees C, and for 2 days at 70degrees C. Taken together, incremental heat increases were associated with the rapid development of A. suum eggs, decreased expression of genes related to viability, and earlier expression of apoptosis-related genes, and finally these changes of viability- and apoptosis-related genes of A. suum eggs were associated with survival of the eggs under temperature stress.
Animals ; *Apoptosis ; Ascaris suum/*genetics/*radiation effects ; Cell Survival/radiation effects ; Eggs/radiation effects ; Female ; Gene Expression Profiling ; Gene Expression Regulation/*radiation effects ; Real-Time Polymerase Chain Reaction ; Survival Analysis ; Temperature

Radiation is the most useful treatment modality for cancer patients. It initiates a series of signal cascades such as DNA damage response (DDR) signaling for repairing damaged DNA, arresting the cell cycle, and inducing cell death. Until now, few genes have been found to be regulated by radiation, which explains the molecular mechanisms of cellular responses to radiation. Although the transcriptional changes caused by radiation have been widely investigated, little is known about the direct evidence for the transcriptional control of DDR-related genes. Here, we examined the radiosensitivity of two non-small cell lung cancer cell lines (H460 and H1299), which have different p53 status. We monitored the time-dependent changes of 24 DDR-related gene expressions via microarray analysis. Based on the basal expression levels and temporal patterns, we further classified 24 DDR-related genes into four subgroups. Then, we also addressed the protein levels of several DDR-related genes such as TopBP1, Chk1 and Chk2, confirming the results of microarray analysis. Together, these results indicate that the expression patterns of DDR-related genes are associated with radiosensitivity and with the p53 statuses of H460 and H1299, which adds to the understanding of the complex biological responses to radiation.
Adaptor Proteins, Signal Transducing/genetics ; Cell Cycle Proteins/genetics ; Cell Line, Tumor ; Cell Survival/radiation effects ; DNA Damage/*radiation effects ; DNA Repair Enzymes/genetics ; DNA-Binding Proteins/genetics ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic/*radiation effects ; Humans ; Lung Neoplasms ; Radiation Tolerance/genetics ; Signal Transduction

The activation of nuclear factor-kappa B1 (NFkappaB1) in cancer cells may confer resistance to ionizing radiation (IR). To enhance the therapeutic efficiency of IR in lung cancer, we screened for microRNAs (miRNAs) that suppress NFkappaB1 and observed their effects on radiosensitivity in a human lung cancer cell line. From time series data of miRNA expression in gamma-irradiated H1299 human lung cancer cells, we found that the expression of miR-9 was inversely correlated with that of NFkappaB1. Overexpression of miR-9 down-regulated the level of NFkappaB1 in H1299 cells, and the surviving fraction of gamma-irradiated cells was decreased. Interestingly, let-7g also suppressed the expression of NFkappaB1, although there was no canonical target site for let-7g in the NFkappaB1 3' untranslated region. From these results, we conclude that the expression of miR-9 and let-7g could enhance the efficiency of radiotherapy for lung cancer treatment through the inhibition of NFkappaB1.
Base Sequence ; Cell Line, Tumor ; Cell Survival/genetics/radiation effects ; Gene Expression Profiling ; *Gene Expression Regulation, Neoplastic/radiation effects ; Humans ; Lung Neoplasms/genetics/metabolism ; MicroRNAs/genetics/*metabolism ; NF-kappa B p50 Subunit/genetics/*metabolism ; Radiation Tolerance/*genetics ; Radiation, Ionizing ; Sequence Alignment

The human Gadd45 protein family plays critical roles in DNA repair, negative growth control, genomic stability, cell cycle checkpoints and apoptosis. Here we report the crystal structure of human Gadd45γ [corrected], revealing a unique dimer formed via a bundle of four parallel helices, involving the most conserved residues among the Gadd45 isoforms. Mutational analysis of human Gadd45γ [corrected] identified a conserved, highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen (PCNA), p21 and cdc2, suggesting that the parallel dimer is the active form for the interaction. Cellular assays indicate that: (1) dimerization of Gadd45γ [corrected] is necessary for apoptosis as well as growth inhibition, and that cell growth inhibition is caused by both cell cycle arrest and apoptosis; (2) a conserved and highly acidic patch on the dimer surface, including the important residues Glu87 and Asp89, is a putative interface for binding proteins related to the cell cycle, DNA repair and apoptosis. These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function.
Amino Acid Motifs ; Animals ; Apoptosis ; radiation effects ; CDC2 Protein Kinase ; Cell Cycle ; Cell Survival ; Crystallography, X-Ray ; Cyclin B ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Cyclin-Dependent Kinases ; HeLa Cells ; Humans ; Intracellular Signaling Peptides and Proteins ; chemistry ; genetics ; metabolism ; Mice ; Mutagenesis, Site-Directed ; Mutation, Missense ; Proliferating Cell Nuclear Antigen ; metabolism ; Protein Binding ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Protein Structure, Quaternary ; Ultraviolet Rays

BACKGROUND AND OBJECTIVECombined hypoxic cytotoxic drugs and chemoradiotherapy is an important mean of oncotherapy, and Tirapazamine (TPZ) is one of the most remarkable drugs. It has been shown that TPZ has a synergistic effect with radiotherapy on tumor cells, but whether TPZ would down-regulate the expression of the hypoxia-induced genes has not been reported. This study was to investigate the hypoxia-induced mRNA expressions of hypoxia inducible factor-1alpha (HIF-1alpha) and osteopontin (OPN) in human nasopharyngeal carcinoma HNE-1 and CNE-1 cells and the radiosensitization of TPZ, a hypoxia-specific drug, on HNE-1 and CNE-1 cells in vitro.

METHODSThe IC50 values of TPZ for HNE-1 and CNE-1 cells were measured using MTT assay, and the mRNA expressions of HIF-1alpha and OPN in HNE-1 and CNE-1 cells was determined using RT-PCR under aerobic and hypoxic conditions, respectively. The survival rates of HNE-1 and CNE-1 cells treated with or without TPZ at IC10 in the presence or absence of oxygen for 6 h were determined using colony formation assay following exposure to 1-6 Gy of 60Co radiation. The dose-survival curves were plotted and the values of D0, Dq and SER were calculated as a single-hit multitarget model.

RESULTSThe IC50 values of TPZ were 34.81 μmol/L and 35.02 μmol/L in HNE-1 and CNE-1 cells under aerobic condition, and 30.20 μmol/L and 28.48 μmol/L under hypoxic condition, respectively. The expressions of HIF-1alpha and OPN mRNA were reduced by TPZ in HNE-1 cells, but not in CNE-1 cells under hypoxic condition. For the HNE-1 cells, the respective values of D0 and Dq were 0.89 Gy and 0.28 Gy following normoxic irradiation versus 1.47 Gy and 0.44 Gy following hypoxic irradiation. For the CNE-1 cells, the respective values of D0 and Dq were 0.72 Gy and 0.68 Gy following normoxic irradiation versus 0.95 Gy and 0.56 Gy following hypoxic irradiation. The values of D0 and Dq for HNE-1 and CNE-1 cells treated with TPZ under hypoxic condition following irradiation were 0.66 Gy, 0.21 Gy and 0.85 Gy, 0.79 Gy, respectively.

CONCLUSIONTPZ can down-regulate hypoxia-induced expression of HIF-1alpha and OPN mRNA of HNE-1 cells and radiosensitize the HNE-1 cells but not CNE-1 cells, and act as a hypoxia modifier.

Antineoplastic Agents ; pharmacology ; Cell Hypoxia ; Cell Line, Tumor ; Cell Survival ; drug effects ; radiation effects ; Cobalt Radioisotopes ; Down-Regulation ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; genetics ; metabolism ; Inhibitory Concentration 50 ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Osteopontin ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Radiation Tolerance ; drug effects ; Radiation-Sensitizing Agents ; pharmacology ; Triazines ; pharmacology