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Background and purpose:As a new and important radiotherapy technique,intensity-modulated radiation therapy(IMRT) has been widely used in the clinic,but it requires longer time to deliver for one treatment session.The purpose of this study was to investigate the radiobiological effects of CNE and A549 cell lines irradiated by IMRT model.Methods:Part Ⅰ:The radiobiological characteristics of CNE and A549 cell lines were studied with standard clonogenic assays,using standard liner-quadratic model and incomplete repair model to fit the dose-survival curves.Part Ⅱ:a total dose of 8 Gy was given in two fractions with different interfraction intervals to compare the differences of cell surviving fractions(SF).Part Ⅲ:fractionated irradiation of 2 Gy,2 Gy?2,2 Gy?3,2 Gy?4 were given with one fraction per day simulating clinical dose-time-fractionation pattern in 2,20 and 40 min per fraction,respectively.Results:The ?/? of CNE and A549 was 1.76 and 12.41 Gy,respectively;the cell surviving fractions increased when the interfraction interval was longer,The values of SF2 were 0.0237 and 0.0243 in 2 min irradiation group,0.0304 and 0.0296 in 20 min irradiation group,and increased to 0.0378 and 0.0359 in 40 min irradiation group,respectively.Conclusion:The prolonged fraction delivery time would significantly decrease theradiobiological effects,it is strongly recommended that the delivery time be kept as short as possible,or do appropriate dose compensation.
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Objective To study the synergistic effect of taxol and irradiation on programmed cell death induction in the human nasopharyngeal carcinoma cell line (CNE) in vitro.Methods Cell viability was evaluated by clonogenic assay. Cell cycle perturbation was assessed by flow cytometric analysis and apoptosis was determined with TUNEL.Results The intensity of cytotoxicity depended on the taxol dose used to CNE cells during the first 24 hrs. A G 2+M block was present with exposure to the drug of 100 nmol/L. When CNE cells were irradiated after 24 hrs of taxol exposure, synergistic effect was demonstrated with a taxol SER of 1.23. The same level apoptosis was induced by 10 ?mol/L taxol for 24 hrs or 2 Gy X-ray radiation in CNE cells.By both,the increase of induced apoptotic cells was over their additive results. Conclusion Taxol combined with radiation is able to enhance the radiosensitivity in the CNE cell line.
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Objective To investigate the change in mRNA expression of hypoxia inducible factor 1? HIF 1? and vascular endothelial growth factor (VEGF) genes in the highly differentiated nasopharyngeal squamous carcinoma (CNE) cell line during hypoxia reoxygenation.Methods CNE cells were cultured in normoxic, continuous 8 hour hypoxia ,16 hour hypoxia and 16 hour hypoxia 4 hour reoxygenation conditions respectively. Expressions of HIF 1? and VEGF genes were assessed by the reverse transcription polymerase chain reaction (RT PCR) technique. Results The mRNA expression of HIF 1? gene was kept constant in the different culture conditions,whereas the mRNA expression of VEGF gene increased significantly after 8 or 16 hour hypoxia and decreased after reoxygenation for 4 hours. Conclusions Hypoxia is able to induce the mRNA expression of VEGF gene in the CNE cell, but is unable to do so in HIF 1? mRNA expression. These findings suggest that VEGF upregulation induced by hypoxia be independent HIF 1a transcription.
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Objective To define the correlation between nasopharyngeal carcinoma (NPC) cell radiosensitivity and gene mutation in the ATM/PI3K coding region. Methods The gene mutation in the ATM/PI3K region of nasopharyngeal carcinoma cell lines which vary in radiosensitivity,was monitored by reverse transcription polymerase chain reaction (RT PCR) and fluorescence marked ddNTP cycle sequencing technique.Results No gene mutation was detected in the ATM/PI3K region of either CNE1 or CNE2.Conclusion Disparity in intrinsic radiosensitivity between different NPC cell lines depends on some other factors and mechanism without being related to ATM/PI3K mutations.
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0.05). However,the expression level of TKTL1 gene was significantly downregulated in the CNE cells transfected with siRNA TKTL1 construct compared with the cells transfected with control vector. Cancer cells were arrested in G0/G1 phase,and cancer cell proliferation was significantly inhibited in the CNE cells transfected with siRNA TKTL1 construct. CONCLUSION:TKTL1 plays an important role in the total transketolase activity and cell proliferation of human nasopharyngeal carcinoma. TKTL1 may be considered as a potential target for novel anti-cancer therapy.