The purpose of this study is to investigate the mechanism of alternative responses to low dose irradiation for neuronal cell proliferation in the dentate gyrus of rats. To determine the effect of a single exposure to radiation, rats were irradiated with a single dose of 0.1, 1, 10 or 20 Gy. To determine the effect of the cumulative dose, the animals were irradiated daily with 0.01 Gy or 0.1 Gy from 1 to 4 days. The neuronal cell proliferation was evaluated using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Four consecutive daily irradiations with a 0.01 Gy/fraction increased the number of BrdU-positive and Ki-67-positive cells in a dose dependent manner, but this did not affect the number of TUNEL-positive cells. However, there was not a dose dependent relationship for the 0.1 Gy/fraction irradiation with the number of BrdU, Ki-67 and TUNEL positive cells. Our data support the explanation that the adaptive response, induced by low-dose radiation, in the hippocampus of rats is more likely a reflection of the perturbations of cell cycle progression.
Rats, Sprague-Dawley ; Rats ; Radiation Dosage ; Neurons/*cytology/*radiation effects ; Neuronal Plasticity/*radiation effects ; Male ; Dose-Response Relationship, Radiation ; Dentate Gyrus/*cytology/*radiation effects ; Cell Survival/radiation effects ; Cell Proliferation/*drug effects ; Animals ; Adaptation, Physiological/radiation effects

OBJECTIVETo study radiation-enhancing effects on human gastric cancer MKN28 cell line and underlying mechanisms of β-elemene.

METHODSInhibition of MKN28 cell proliferation at different concentrations of β-elemene was assessed using the methyl thiazolyl blue colorimetric method (MTT method), with calculation of IC50 value and choice of 20% of the IC50 as the experimental drug concentration. Irradiation group and β-elemene+irradiation group were established, and the cell survival fraction (SF) was calculated from flat panel colony forming analysis, and fitted by the 'multitarget click mathematical model'. Draw the survival curve and get the radiobiological parameters D0, Dq, SF2, N and SER. Flow cytometry (FCM) was used to detect changes in the cell cycle and cell apoptosis rates was detected by Annexin-V/PI assay.

RESULTSβ-elemene exerted inhibitory effects on proliferation of gastric cancer MKN28 cells, with an IC50 of 45.6 mg/L and we chose 8 mg/L as the experimental concentration. The cell survival fraction of MKN28 cells with irradiation decreased significantly after treated with β-elemene; D0, Dq decreased, SER = 1.3. After combined treatment of β-elemene+irradiation, the results of FCM showed that cells could be arrested in the G2/M phase and the cell apoptosis increased significantly.

CONCLUSIONSβ-elemene can enhance the radiosensitivity of gastric cancer MKN28 cell line. Mechanistically, β-elemene mainly influences the cell cycle distribution of MKN28 cells by inducing G2/M phase arrest, inhibits the repair of sublethal damage and induces cell apoptosis to enhance the killing effects of radioactive rays.

Apoptosis ; drug effects ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Humans ; Radiation Tolerance ; drug effects ; Sesquiterpenes ; pharmacology ; Stomach Neoplasms ; pathology

OBJECTIVETo study effects of hypericin associated with light irradiation on human laryngeal squamous cell carcinoma strain Hep-2.

METHODSUsing techniques of tumor cells culture in vitro, Hep-2 cells were exposed to different concentration hypericin as 0.5, 1.0, 2.0, 3.0, 5.0 microg/ml, then 10 minutes 7.5 J/cm2 light irradiation was given after an hour. Other groups Hep-2 culture cells were also exposed to different concentration hypericin as 5.0, 10.0, 20.0, 25.0 microg/ml, without light irradiation. In all groups, contrast groups were set up. And 48 hours later, growth characteristics of Hep-2 cells were studied by morphological observation, fluorescence microscope, MTT assay and flow cytometry.

RESULTSIn normal contrast group, Hep-2 cells grew intensively and contacted with each other. However, cells which were treated with hypericin, combination with light irradiation were declined greatly. In higher dose hypericin group, necrosis could be found. MTT assay showed that hypericin associated with light irradiation inhibited growth of laryngeal cell with dose dependence manner. Flow cytometry showed that hypericin with light irradiation could block cell growth at G0/G1 phase, inducing apoptosis of laryngeal cell. Under fluorescence microscope, some sings of cell apoptosis including coagulation of chromatin, fragmentation of nuclei and apoptotic body could be found.

CONCLUSIONHuman laryngeal squamous cell carcinoma strain Hep-2 can be inhibited and induced into apoptosis by treated with hypericin combination with light irradiation.

Apoptosis ; drug effects ; radiation effects ; Carcinoma, Squamous Cell ; pathology ; Cell Proliferation ; drug effects ; radiation effects ; Hep G2 Cells ; Humans ; Laryngeal Neoplasms ; pathology ; Light ; Perylene ; analogs & derivatives ; pharmacology

OBJECTIVETo study the radiosensitizing effect of gefitinib on nasopharyngeal carcinoma cell line CNE2 in vitro.

METHODSNasopharyngeal carcinoma cell line CNE2 was cultured in RP2MI 1640. MTT assay was performed to evaluate the cell proliferation changes in response to gefitinib treatment and the radiosensitizing effect of gefitinib. The cell survival curves and sensitive enhancement ratio (SERs) were obtained with a clonogenic assay. Flow cytometry analysis was applied to detect the cell cycle changes and cell apoptosis.

RESULTSMTT assay showed that cells exposed to gefitinib and radiation had a significantly lower survival ratio compared to the cells with radiation exposure only (0.582∓0.012 vs 0.398∓0.016, P=0.002), with a SER of 1.535∓0.134. The S phase cell percentage was significantly decreased and G(2)-M phase cells increased in gefitinib plus radiation group (P=0.000), suggesting a synergistic effect of gefitinib and radiation.

CONCLUSIONGefitinib can enhance the radiosensitivity of nasopharyngeal carcinoma CNE2 cells in vitro possibly by inhibiting cell proliferation, inducing cell apoptosis, and causing changes in the cell cycle distribution.

Apoptosis ; drug effects ; Carcinoma ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Flow Cytometry ; Humans ; Nasopharyngeal Neoplasms ; pathology ; Quinazolines ; pharmacology ; Radiation Tolerance ; drug effects

OBJECTIVETo investigate the effects of the ultra-filtration extract mixture from Hedysarum Polybotrys (UEMHP) on the radiosensitivity of HepG2 cells, and to explore its possible mechanisms.

METHODSThe proliferation inhibition effects of UEMHP on HepG2 cells was detected by CCK-8 assay. The colony formation assay was used for the survival fraction (SF) analysis. The distribution of the cell cycle and the apoptosis rate were detected using flow cytometry (FCM). The survivin mRNA expression level was detected using reverse transcription-PCR assay.

RESULTSThe inhibition of UEMHP on HepG2 cells was time-and dose-dependent at the concentration ranging between 5 -50 mg/L (P < 0.05). The parameters of the two curve for SF (P < 0.05) showed statistical difference between the irradiation group and the UEMHP irradiation group. UEMHP could inhibit the clone formation of HepG2 cells and enhance the radiosensitivity of HepG2 cells. The results of FCM showed that UEMHP could induce G2/M phase arrest. The apoptosis rate in the UEMHP irradiation group (21.42% +/- 3.74%) was higher than that in the control group (5.35% +/- 0.41%), the only UEMHP group (10.36% +/- 1.75%), or the irradiation group (10.58% +/- 2.01%) (P < 0.01). RT-PCR showed that the survivin mRNA expression level was lower in the UEMHP irradiation group (0.31 +/- 0.02) than in the control group (0.82 +/- 0.06) and the irradiation group (0.58 +/- 0.04) respectively, showing statistical difference (P < 0.01).

CONCLUSIONUEMHP can enhance the radiosensitivity of HepG2 cells, and its possible mechanisms might be correlated to down-regulating the survivin mRNA expression and promoting the apoptosis.

Apoptosis ; Cell Proliferation ; drug effects ; radiation effects ; Drugs, Chinese Herbal ; pharmacology ; Hep G2 Cells ; Humans ; Inhibitor of Apoptosis Proteins ; metabolism ; Radiation Tolerance ; drug 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 observe the effects of calcium phosphate cement/eucommia ulmoides extracts compound (CPC/EUE) on cell proliferation and adhesion of MC3T3E1 osteoblasts in vitro.

METHODSCultured MC3T3E1 osteoblasts were divided into 5 groups: blank control, CPC/EUE 0, 0.152, 0.304 and 0.608 mg/ml. 3H-TdR and scan electronic microscopy (SEM) were used to observe the cell growth, proliferation and adhesion.

RESULTThe CPC/EUE compound enhanced the cell growth, proliferation and adhesion. The concentrations of 0.152 mg/ml, 0.304 mg/ml were more significant in enhancing the cell proliferation rate (P<0.05).

CONCLUSIONCPC/EUE can promote the cell growth, proliferation and adhesion of the osteoblasts.

Alkaline Phosphatase ; metabolism ; Bone Cements ; Calcium Phosphates ; pharmacology ; Cell Adhesion ; radiation effects ; Cell Differentiation ; radiation effects ; Cell Proliferation ; radiation effects ; Cells, Cultured ; Gonadotropins ; metabolism ; Humans ; Osteoblasts ; cytology ; drug effects ; Tissue Adhesions

OBJECTIVETo investigate the interference effect of nicotinamide on UVA-induced cell proliferation in human skin melanocyte.

METHODSTo apply the optimum UVA dose expected to cause cell proliferation: 0.2 cm2, nicotinamide was added after the 0.2 cm2 UVA exposure immediately or 48 h later, then the rate of cell proliferation, calcium concentration and the activities of Na+-K+, Ca2+-ATP enzymes of melanocytes were measured respectively.

RESULTSAfter treatment with 1.000 mg/ml nicotinamide following UVA exposure, the rate of cell proliferation was decreased significantly 24 hours later. Treatment with 0.125 mg/ml nicotinamide 48 hours after UVA exposure also significantly inhibited the cell proliferation; 1.25 mg/ml nicotinamide increased calcium concentration in cells; 0.250 mg/ml nicotinamide increased the activities of Na+-K+, Ca2+-ATP enzymes in melanocytes (P < 0.05).

CONCLUSIONNicotinamide has more obvious effect on inhibiting melanocyte's proliferation if added immediately following UVA exposure. Our discovery indicated that nicotinamide may affect the melanocyte through modulating the calcium concentration. It is possible to consider nicotinamide as an efficient and safe sun screen to provide a certain level of protection for UVA exposed skin.

Cell Proliferation ; drug effects ; radiation effects ; Cells, Cultured ; Humans ; Melanocytes ; cytology ; Niacinamide ; pharmacology ; Skin ; cytology ; Ultraviolet Rays

BACKGROUND: Lung cancer is one of the highest morbidity and mortality in the world and it is very important to find an effective anti-tumor method. Microwave hyperthermia, a new treatment technology, has been getting more and more attention. This study was designed to investigate the effects of microwave hyperthermia combined with gemcitabine on the proliferation and apoptosis of human lung squamous cell carcinoma (NCI-H1703 and NCI-H2170) in vitro. METHODS: The proliferation of cells treated with microwave hyperthermia, the effect of gemcitabine on cell proliferation and the proliferation of cells treated with different methods of microwave hyperthermia and gemcitabine were detected by CCK-8 assay. Colony formation assay was used to measure the colony formation of human lung squamous cell carcinoma cells. Flow cytometry assay was used to detect the total apoptosis rates of the treated cells. Caspase-3, Caspase-8 activity assay was used to detect the activity of Caspase-3, Caspase-8 enzyme in each group of cells. CCK-8 assay was used to detect the effect of control group, AC-DEVD (Caspase-3 inhibitor) group, thermalization combined group, and thermal AC-DEVD combined group on cell proliferation. The levels of p53, Caspase-3, Cleaved-Caspase-3, PARP, Bax and BCL-2 protein expression were detected using Western blot assay. RESULTS: Our results demonstrated that microwave hyperthermia inhibited the proliferation of lung squamous cell carcinoma. The IC₅₀ values of gemcitabine for the two cells were 8.89 μmol/L and 44.18 μmol/L, respectively. The first chemotherapy after microwave hyperthermia has synergistic effect on the two lung squamous cell carcinoma cells and can significantly inhibit the cell clone formation (P<0.001), promote cell apoptosis (P<0.001) and increase Caspase-3 enzyme activity (P<0.001). However, it has no effect on Caspase-8 enzyme activity (P>0.05). Furthermore, Western blot analysis showed that microwave hyperthermia combined with gemcitabine could up-regulate the p53, Caspase-3, Cleaved-Caspase-3, Cleaved-PARP and Bax protein expression. CONCLUSIONS Microwave hyperthermia combined with gemcitabine remarkably inhibit the proliferation and induce apoptosis of human lung squamous cell carcinoma in vitro. This effect may be associated with the activation of p53, cleavage of PARP protein, and induced the Caspase-3 dependent apoptosis.
Apoptosis ; drug effects ; radiation effects ; Carcinoma, Squamous Cell ; pathology ; Caspase 3 ; metabolism ; Caspase 8 ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; radiation effects ; Combined Modality Therapy ; Deoxycytidine ; analogs & derivatives ; pharmacology ; Humans ; Hyperthermia, Induced ; Lung Neoplasms ; pathology ; Microwaves

OBJECTIVETo investigate the radiosensitizing effect of nitric oxide (NO) combined with radiation on esophageal cancer cell line TE-1.

METHODSMethyl thiazolyl tetrazolium (MTT) assay was used to assess the effects of NO and radiation on TE-1 cells regarding inhibition of cell proliferation. Flow cytometry was used to examine the effect of NO and radiation on cell apoptosis and cycle. Reverse transcription polymerase chine reaction and Western blot were used to evaluete the effect of NO on mRNA and protein expression of manganese superoxide dismutase (MnSOD).

RESULTSNO inhibited the proliferation of TE-1 cells while significantly enhancing their radiosensitivity. The application of NO combined with radiation significantly increased the apoptosis rate and G2/M phase proportion of TE-1 cells, with substantial decreases in the MnSOD mRNA and protein expression levels.

CONCLUSIONSNO reduces the MnSOD mRNA and protein expression levels by affecting TE-1 cell cycle, further inhibiting the apoptosis of esophageal cancer cells and enhancing the killing effect of radiation on esophageal cancer cells.

Cell Line, Tumor ; Cell Proliferation ; drug effects ; Esophageal Neoplasms ; drug therapy ; metabolism ; pathology ; Humans ; Nitric Oxide ; therapeutic use ; Radiation Tolerance ; drug effects ; Superoxide Dismutase ; metabolism