RESUMEN
Objective: To investigate the effects of histone deacetylase inhibitor trichostatin A (TSA) on radiosensitivity of human cervical cancer cell line HeLa under hypoxia condition. Methods: Under hypoxia condition, the HeLa cells were treated with different concentrations of TSA for 12, 24, 48 and 72 h, respectively. The survival rate of HeLa cells was detected by MTT assay. The half inhibitory concentration (IC50) and IC10 values for TSA were calculated. The radiosensitivity in HeLa cells treated with TSA (IC10) for 24 h under hypoxia condition was detected by colony formation assay. The expressions of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) proteins were measured by immunocytochemistry. Results: The survival rate of HeLa cells induced by TSA and hypoxia was decreased in a concentration and time-dependent manner. The radiosensitivity of HeLa cells under hypoxia condition was increased by treatment with TSA (IC10) for 24 h (P <0.05). The expressions of HIF-1α and VEGF proteins were higher in HeLa cells exposed to hypoxia than that in HeLa cells exposed to normoxia. The expressions of HIF-1α and VEGF proteins in HeLa cells under hypoxia condition were decreased by treatment with TSA (IC10) for 24 h. Conclusion: TSA can significantly enhance the radiosentivity of HeLa cells under hypoxia condition. This effect may be related with the down-regulation of HIF-1α and VEGF protein expression. Copyright© 2011 by the Editorial Board of Tumor.
RESUMEN
Objective: To identify key transcriptional regulatory regions of ezrin gene in HeLa cells, thus this work maked a preliminary study for revealing its transcriptional regulatory mechanism. Methods: The recombinant pGLB plasmids containing different lengths of DNA fragments upstream of translation initiation site of ezrin gene as reporter promoters were constructed using nested-deletion method, and the promoter activities were detected using dual-luciferase reporter assay system. The potential transcription factor binding sites at key transcriptional regulatory region of ezrin gene were predicted using on-line analyzing programme. Results: The recombinant pGLB plasmids containing different lengths of 5′-flanking region of ezrin gene were obtained. When the lengths of ezrin 5′-flanking region were reduced from - 1 324 to - 890, the transcriptional activity decreased by about 80%. If the length of 5′-flanking region were deleted from - 146 to - 32, the transcriptional activities were nearly abolished. Sp 1 transcriptional factor binding sites were ubiquitous at the - 1 324/ - 890 and - 146/ - 32 regions. Conclusion: The - 1 324/ - 890 and - 146/ - 32 regions were two key transcriptional regulatory regions of ezrin gene in HeLa cells. Sp 1 may be an important factor for regulating the transcription of ezrin gene.