OBJECTIVETo investigate the effects of radiosensitivity and X-ray dose on the expression of miR-7 in nasopharyngeal carcinoma (NPC) cells.

METHODSLow radiosensitive NPC cells CNE-1 and high radiosensitive NPC cells CNE-2 were exposed to 0, 2 and 8 Gy X-ray. The total RNAs of the cell lines were extracted 10 h after radiation for reverse transcription of miR-7 and 18S rRNA by stem-loop primer and random hexamers, respectively. The non-irradiated CNE-1 cells served as the control sample and the relative quantity of the expression level was calculated after real-time PCR using SyBR green.

RESULTSmiR-7 expression differed significantly between CNE-1 and CNE-2 cells (4.49-/+3.62 vs 1.29-/+1.10, F=135.483, P<0.001). The radiation dose also significantly affected the expression of miR-7 in NPC cells (F=39.565, P<0.001). CNE-1 cells with a 2 Gy exposure had the highest expression level of miR-7, while the non-irradiated CNE-1 cells had the lowest expression. CNE-2 cells exposed to 2 Gy X-ray had the lowest expression level of miR-7 and the non-irradiated CNE-2 cells had the highest.

CONCLUSIONRadiosensitivity and radiation dose of X-ray have significant effect on the expression of miR-7 in NPC cells, indicating that miR-7 plays an important role in radioresistance of NPC cells to X-ray, and suppressed miR-7 expression may elevate the radiosensitivity of NPC cells.

Apoptosis ; radiation effects ; Carcinoma ; Cell Line, Tumor ; Dose-Response Relationship, Radiation ; Gene Expression Regulation, Neoplastic ; radiation effects ; Humans ; MicroRNAs ; genetics ; Nasopharyngeal Neoplasms ; genetics ; Radiation Tolerance ; genetics ; X-Rays

OBJECTIVETo explore the method of inducing and building pancreatic cancer cell sublines with radiation resistance.

METHODSSimulating the clinical radiotherapy, the pancreatic cell lines SW1990, Capan-1 (Cap), AsPC-1 (ASPC), P3, PANC-1 (Pan-1) and MIAPaCa-2 (MIA) were repeatedly given individual dose of X-rays with liner accelerator to induce radiation resistance, the changes of cell morphology, cell cycle and radio sensibility in the induced cell lines were compared with the parental cell lines at the end of inducing course.

RESULTSCompared with the parental cells, there were significant changes in morphology in the pancreatic cancer cell sublines after the radiation. Cell cycle analysis suggested that SW1990-R, ASPC-R, MIA-R, PAN-R and P3-R had lower G(2)/M and greater SF(2) (survival fraction after 2 Gy irradiation) compared with the parental cell lines.

CONCLUSIONSThe method of radiating cells step by step and repeatedly is viable to establish radio-resistant pancreatic cancer cell lines.

Cell Culture Techniques ; methods ; Cell Cycle ; radiation effects ; Cell Line, Tumor ; Cell Proliferation ; radiation effects ; Cell Shape ; radiation effects ; Cell Size ; radiation effects ; Cell Survival ; radiation effects ; Dose-Response Relationship, Radiation ; Humans ; Pancreatic Neoplasms ; pathology ; physiopathology ; Radiation Tolerance

OBJECTIVETo seek for the appropriate concentration, at which IGF-II can exerts its strong effects on postirradiation proliferation, physiological function and differentiation of the rat's osteoblast-like cells (ROB).

METHODSThe osteoblast-like cells used were isolated from the calvariae of neonatal (one-day-old) SD rats by sequential enzymatic digestion. The third passages of the cells were irradiated with gamma-ray from a (60)Co source at the doses of 100, 400, 600, and 900 cGy. The medium was changed immediately after irradiation and 5 concentrations of IGF-II, i.e., 0, 0.1, 1.0, 10.0, and 100.0 microgram/L were added. 6 days after radiation (9 days in culture), the examination, or the measurement of relative cell number, was carried out.

RESULTSRadiation inhibited the ROB, even lethally. IGF-II completely counteracted the inhibitory effects when the cells were exposed to the radiation at lower dose (100 cGy), and partially when at higher dose (400 cGy). But after the radiation at much higher dose as 900 cGy, the damages were irreversible, even with the existence of this growth factor.

CONCLUSIONSAt least a portion of effective recovery of postirradiation damages may be due to IGF-II-induced radioresistance. Incubation with IGF-II can increase radioresistance or repair of radiation-induced cells damages. However, this effect depends on the dose of radiation.

Animals ; Cell Division ; drug effects ; radiation effects ; Cells, Cultured ; Dose-Response Relationship, Drug ; Dose-Response Relationship, Radiation ; Insulin-Like Growth Factor II ; pharmacology ; Osteoblasts ; drug effects ; physiology ; radiation effects ; Radiation Tolerance ; drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo evaluate the radiosensitization of paclitaxel combined with radiation on nasopharygneal carcinoma cells( CNE-I) in vitro.

METHODSHuman CNE-I cells were used for this study. Clonogenic assay was used to determine the drug dose of IC10, IC50 and IC90 for CNE-I Cells. The cells treated with different concentration of paclitaxel for 24 hours before or after radiation (dose ranged from 0 - 10 Gy ) were used to evaluate the radiosensitizing effect of paclitaxel combined with radiation. DNA flow cytometry was performed to define the cell cycle characteristics of cell populations treated for 0, 2, 6, 12, 18, 24 h with 0.1 nmol/L, 0.5 nmol/L, 1.0 nmol/L, 2.5 nmol/L paclitaxel, respectively.

RESULTSThe dose of IC10, IC50 and IC90 for paclitaxel in CNE-I cells was 0.05 nmol/L, 1.0 nmol/L and 2.5 nmol/L, respectively. Paclitaxel treatment at concentration of 0.05 nmol/L and 1.0 nmol/L for 24 hours combined with X-ray irradiation before or after radiation showed radiosensitivity-enhansing effects in CNE-I cells. G2/M block was present when the drug concentrations were 2.5 nmol/L and 10.0 nmol/L, and it peaked at 18 hours.

CONCLUSIONWith an optimal paclitaxel/radiation combination, paclitaxel may exert a radiosensitizing effect on CNE-I cells. The effect might be related to the G2/M block caused by paclitaxel.

Antineoplastic Agents, Phytogenic ; pharmacology ; Carcinoma, Squamous Cell ; pathology ; Cell Cycle ; drug effects ; radiation effects ; Cell Line, Tumor ; Cell Survival ; drug effects ; radiation effects ; Dose-Response Relationship, Drug ; Dose-Response Relationship, Radiation ; Humans ; Nasopharyngeal Neoplasms ; pathology ; Paclitaxel ; administration & dosage ; pharmacology ; Particle Accelerators ; Radiation Tolerance ; drug effects ; Radiation-Sensitizing Agents ; pharmacology

OBJECTIVE: To study the relationship between the radiotherapy resistance and autophagy. To provide a theoretiacal basis for drugs that regulate autophagy to improve radiotherapy sensitivity. METHOD: Flow cytometry (FCM) was performed to analyze the distribution of the cell cycle of CNE2 and CNE2/DDP cells under the action of X radiation. The expression of autopagy-specific gene Beclin1 and microtubule-associated protein light chain 3β (MAPLC3β) in CNE2 and CNE2/DDP cells was determined by real time PCR and Immumofluorescence staining. RESULT: CNE2/DDP and their parental CNE2 cells produced the G2-M phase arrest under the action of X radiation. With the radiation dose increasing,The cells which in the G2-M phase were more and more (P<0. 05). The G2-M phase arrest in CNE2/DDP cells was more obvious than in CNE2 cells (P<0. 05). The expression of Beclin1 and MAPLC3β in CNE2 and CNE2/DDP cells increased under the action of X radiation. What's more, the raise was more and more obvious with the increase of the irradiation dose(P<0. 05). The expression levels of Beclin1 and MAPLC3β in CNE2/DDP was lower than that in CNE2 cells (P<0. 05). CONCLUSION Autophagic cell death may be the one manner of death in nasopharyngeal carcinoma CNE2 and CNE2/DDP cells under the action of X radiation. The radiation resistance of CNE2/DDP cells may be related to the low expression of autophagy-related genes.
Apoptosis Regulatory Proteins ; genetics ; Autophagy ; Beclin-1 ; Carcinoma ; Cell Cycle ; Cell Line, Tumor ; radiation effects ; Dose-Response Relationship, Radiation ; Humans ; Membrane Proteins ; genetics ; Microtubule-Associated Proteins ; genetics ; Nasopharyngeal Carcinoma ; Nasopharyngeal Neoplasms ; genetics ; Radiation Tolerance ; X-Rays

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

To evaluate radiosensitivity and the effects of radiation on the expression of vascular endothelial growth factor (VEGF) and VEGF receptors in the canine oral melanoma cell line, TLM 1, cells were irradiated with doses of 0, 2, 4, 6, 8 and 10 Gray (Gy). Survival rates were then determined by a MTT assay, while vascular endothelial growth factor receptor (VEGFR)-1 and -2 expression was measured by flow cytometry and apoptotic cell death rates were investigated using an Annexin assay. Additionally, a commercially available canine VEGF ELISA kit was used to measure VEGF. Radiosensitivity was detected in TLM 1 cells, and mitotic and apoptotic cell death was found to occur in a radiation dose dependent manner. VEGF was secreted constitutively and significant up-regulation was observed in the 8 and 10 Gy irradiated cells. In addition, a minor portion of TLM 1 cells expressed vascular endothelial growth factor receptor (VEGFR)-1 intracellularly. VEGFR-2 was detected in the cytoplasm and was down-regulated following radiation with increasing dosages. In TLM 1 cells, apoptosis plays an important role in radiation induced cell death. It has also been suggested that the significantly higher VEGF production in the 8 and 10 Gy group could lead to tumour resistance.
Animals ; Apoptosis/*radiation effects ; Cell Line, Tumor/radiation effects ; Dogs ; Dose-Response Relationship, Radiation ; Enzyme-Linked Immunosorbent Assay/veterinary ; Melanoma/genetics/metabolism ; Mouth Neoplasms/genetics/metabolism ; Radiation Tolerance ; Tetrazolium Salts/metabolism ; Thiazoles/metabolism ; Up-Regulation/*radiation effects ; Vascular Endothelial Growth Factor A/genetics/metabolism/*radiation effects ; Vascular Endothelial Growth Factor Receptor-1/genetics/metabolism/*radiation effects ; Vascular Endothelial Growth Factor Receptor-2/genetics/metabolism/*radiation effects

OBJECTIVETo explore the radiosensitizing effect of erlotinib on human lung adenocarcinoma cell line A549 cells and the related mechanisms.

METHODSThe inhibitory effect of erlotinib on A549 cells was assessed by MTT assay, and its IC50 concentration was calculated. The radiosensitization was evaluated by the method of clone forming assay. Flow cytometry was used to analyze the effect of erlotinib on cell cycle and apoptosis.

RESULTSThe growth of A549 cells was inhibited after the cells were exposed to erlotinib for 48 hours. Moreover, the inhibitory rates increased with the increase of erlotinib concentrations, and IC50 was 19.26 µmol/L. In contrast to the irradiation alone group, the survival rates of the cells in erlotinib plus irradiation groups decreased, and erlotinib enhanced the radiosensitivity of the A549 cells. This effect was further increased as cells were exposed to erlotinib for a longer time. In the irradiation alone group and the two groups exposed to erlotinib for 24 hours and 48 hours before irradiation, D0 values were 3.01 Gy, 2.58 Gy and 2.45 Gy respectively, and Dq values were 2.16 Gy, 1.94 Gy and 1.61 Gy, respectively. In the last two groups, SERD0 values were 1.17 and 1.23, respectively. The flow cytometry analysis showed that erlotinib induced G2/M phase arrest and increased the apoptosis rate in A549 cells. With the increase of exposure time, the effects were more significant.

CONCLUSIONSErlotinib inhibits the A549 cell growth and enhances the radiosensitivity of A549 cells in vitro. The radiosensitizing mechanisms might be related to inhibiting repair of sublethal injury and inducing G2/M phase arrest and apoptosis.

Adenocarcinoma ; pathology ; Apoptosis ; drug effects ; radiation effects ; Cell Cycle ; drug effects ; radiation effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; radiation effects ; Dose-Response Relationship, Drug ; Erlotinib Hydrochloride ; Humans ; Lung Neoplasms ; pathology ; Particle Accelerators ; Quinazolines ; administration & dosage ; pharmacology ; Radiation Tolerance ; drug effects ; Radiation-Sensitizing Agents ; administration & dosage ; pharmacology

OBJECTIVETo investigate the changes of ataxia-telangiectasia mutated (ATM) phosphorylation in HepG(2) cells in relation to HepG(2) cell survival under continuous low dose-rate irradiation.

METHODSHepG(2) cells were exposed to equivalent irradiation doses delivered at either a continuous low dose-rate (7.76 cGy/h) or a high dose-rate (4500 cGy/h), and the phosphorylated ATM proteins and surviving fraction of HepG(2) cells after the exposures were compared.

RESULTSThe phosphorylation of ATM protein was maximal at 0.5 Gy irradiation delivered at either a high doserate or a continuous low doserate. As the radiation dose increased, ATM protein phosphorylation decreased under continuous low dose-rate irradiation, but remained stable under high dose-rate irradiation. With comparable ATM protein phosphorylation induced by continuous low dose-rate irradiation and high dose-rate irradiation, there was no significant difference in the surviving fraction of HepG(2) cells (P>0.05), but at a significantly lower ATM protein phosphorylation level than that induced by high dose-rate irradiation, continuous low dose-rate irradiation resulted in increased cell killing (P<0.01).

CONCLUSIONContinuous low dose-rate irradiation increases HepG(2) cells radiosensitivity as compared with high dose-rate irradiation. Increased cell killing following continuous low dose-rate irradiation is associated with reduced phosphorylated ATM protein, and inhibition of ATM phosphorylation may increase the radiosensitivity of HepG(2) cells.

Animals ; Ataxia Telangiectasia Mutated Proteins ; Cell Cycle Proteins ; metabolism ; Cell Line, Tumor ; Cell Survival ; radiation effects ; DNA-Binding Proteins ; metabolism ; Dose-Response Relationship, Radiation ; Humans ; Mice ; Phosphorylation ; radiation effects ; Protein-Serine-Threonine Kinases ; metabolism ; Radiation Tolerance ; radiation effects ; Time Factors ; Tumor Suppressor Proteins ; metabolism

BACKGROUNDRadiotherapy plays a critical role in the management of non-small cell lung cancer (NSCLC). This study was conducted to identify gene expression profiles of acquired radioresistant NSCLC cell line established by fractionated ionizing radiation (FIR) by cDNA microarray.

METHODSThe human lung adenocarcinoma cell line Anip973 was treated with high energy X-ray to receive 60 Gy in 4 Gy fractions. The radiosensitivity of Anip973R and its parental line were measured by clonogenic assay. Gene expression profiles of Anip973R and its parental line were analyzed using cDNA microarray consisting of 21 522 human genes. Identified partly different expressive genes were validated by quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR).

RESULTSFifty-nine upregulated and 43 downregulated genes were identified to radio-resistant Anip973R. Up-regulated genes were associated with DNA damage repair (DDB2), extracellular matrix (LOX), cell adhesion (CDH2), and apoptosis (CRYAB). Down-regulated genes were associated with angiogenesis (GBP-1), immune response (CD83), and calcium signaling pathway (TNNC1). Subsequent validation of selected eleven genes (CD24, DDB2, IGFBP3, LOX, CDH2, CRYAB, PROCR, ANXA1 DCN, GBP-1 and CD83) by Q-RT-PCR was consistent with microarray analysis.

CONCLUSIONSFractionated ionizing radiation can lead to the development of radiation resistance. Altered gene profiles of radioresistant cell line may provide new insights into mechanisms underlying clinical radioresistance for NSCLC.

Adenocarcinoma ; genetics ; radiotherapy ; Carcinoma, Non-Small-Cell Lung ; genetics ; radiotherapy ; Cell Line, Tumor ; radiation effects ; Dose Fractionation ; Dose-Response Relationship, Radiation ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Humans ; Lung Neoplasms ; genetics ; radiotherapy ; Oligonucleotide Array Sequence Analysis ; Radiation Tolerance ; Reverse Transcriptase Polymerase Chain Reaction