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Gamma Radiation Induces Apoptosis by Over Expression of PERP Effector of p53-dependent Cell Death in HeLa Cells.
* 1 , 2
1  Department of Forensic Sciences, Al-Istiqlal University, Jericho, Palestine
2  Faculty of Science, Biology, Istanbul University, 34126 Istanbul, Turkey


Ionized radiation leads to a modulation of the expression of many genes. Identification of specific genes may allow the determination of pathways important in radiation responses. It was found that PERP induces apoptosis when it is overexpressed. However, the mechanism by which PERP induces apoptosis is still unknown. The objectives of this study were to determine the configuration of several genes in response to gamma radiation treatment. Novel treatment strategy to increase the cancer cell sensitivity to radiotherapy by modulation of the PERP expression could be developed for cervical cancers.

Cervical cancer cells were incubated for several periods after were exposed to various doses of gamma radiation, MTT assay were used to explore propagation of HeLa cells, apoptotic Index (AI) were measured using fluorescent microscopy by estimating apoptotic morphological features. While, signalling pathway analyses were performed on up-regulated genes which evaluated using microarray technology.

From the results of this study, the proliferation of HeLa cervical cancer cells exposed to gamma radiation was inhibited proportionally with dose and time after exposure. Also, apoptotic morphological features, such as shrinkage of the cell and formation of apoptotic bodies, was clearly visible under the microscope for irradiated HeLa cells. after 48 h. exposure to different doses of gamma radiation, the dose of 32 Gy was specified as an AI dose. The mRNA levels of pro-apoptotic genes such as, PERP; BAX; CASP9; TRAF3 and other factors detected by microarray after treatment with gamma radiation were up-regulated. Whereas, many anti-apoptosis factors were down-regulated. P53 pathway were significantly reinforced after pathway analysis for up- and dawn- regulated genes. For conclusion, gamma radiation induces apoptosis by over expression of PERP factor and p53-dependent cell death in cervical carcinoma HeLa cells.

Keywords: Apoptosis; Ionizing Radiation; HeLa cells; PERP; Microarray; MTT assay; DAPI staining.