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Up-regulation of Bcl-2 expression in cultured human lymphocytes after exposure to low doses of gamma radiation.

Azimian H, Bahreyni-Toossi MT, Rezaei AR, Rafatpanah H, Hamzehloei T, Fardid R - J Med Phys (2015 Jan-Mar)

Bottom Line: In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated.Modification of these gene expressions seems to be a principle pathway in the early radioresistance response.In our study, we found that these changes were temporary and faded completely within a week.

View Article: PubMed Central - PubMed

Affiliation: Medical Physics Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

ABSTRACT
Lymphocytes have demonstrated complex molecular responses to induced stress by ionizing radiation. Many of these reactions are mediated through modifications in gene expressions, including the genes involved in apoptosis. The primary aim of this study was to assess the effects of low doses of ionizing radiation on the apoptotic genes, expression levels. The secondary goal was to estimate the time-effect on the modified gene expression caused by low doses of ionizing radiation. Mononuclear cells in culture were exposed to various dose values ranged from 20 to 100 mGy by gamma rays from a Cobalt-60 source. Samples were taken for gene expression analysis at hours 4, 24, 48, 72, and 168 following to exposure. Expression level of two apoptotic genes; BAX (pro-apoptotic) and Bcl-2 (anti-apoptotic) were examined by relative quantitative real-time polymerase chain reaction (PCR), at different time intervals. Radio-sensitivity of peripheral blood mononucleated cells (PBMCs) was measured by the Bcl-2/BAX ratio (as a predictive marker for radio-sensitivity). The non-parametric two independent samples Mann-Whitney U-test were performed to compare means of gene expression. The results of this study revealed that low doses of gamma radiation can induce early down-regulation of the BAX gene of freshly isolated human PBMCs; however, these changes were restored to near normal levels after 168 hours. In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated. Four hours following to exposure to low doses of gamma radiation, apoptotic gene expression is modified, this is manifested as adaptive response. Modification of these gene expressions seems to be a principle pathway in the early radioresistance response. In our study, we found that these changes were temporary and faded completely within a week.

No MeSH data available.


Related in: MedlinePlus

Effect of elapsed time on relative quantification (RQ) after irradiation to (a) 20 mGy, (b) 50 mGy, and (c) 100 mGy. Gene expression results are presented in terms of the base-2 logarithm of the RQ; positive and negative values represent increased and decreased gene expression level, respectively. Each point represents the mean of four individual experiments and error bars show the S.E
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Figure 2: Effect of elapsed time on relative quantification (RQ) after irradiation to (a) 20 mGy, (b) 50 mGy, and (c) 100 mGy. Gene expression results are presented in terms of the base-2 logarithm of the RQ; positive and negative values represent increased and decreased gene expression level, respectively. Each point represents the mean of four individual experiments and error bars show the S.E

Mentions: In this study, the effect of elapsed time following exposure was also examined. Early down-regulation of BAX gene expression induced by 20, 50, and 100 mGy, 4 hours following irradiation is shown in Figure 2a–c. This phenomenon was terminated 168 hours after delivery of 20 and 50 mGy. Maximum reduction in BAX gene expression was observed 4 hours following to 20 and 100 mGy [Figure 2a and b], similar result was observed 24 hours after 50 mGy [Figure 2c]. Low doses of gamma gave rise to up-regulation of Bcl-2 expression. The highest increase was noticed at 72 hours following to 50 mGy [Figure 2b], this was also true for delivery of 100 mGy at 24 hours after irradiation [Figure 2c].


Up-regulation of Bcl-2 expression in cultured human lymphocytes after exposure to low doses of gamma radiation.

Azimian H, Bahreyni-Toossi MT, Rezaei AR, Rafatpanah H, Hamzehloei T, Fardid R - J Med Phys (2015 Jan-Mar)

Effect of elapsed time on relative quantification (RQ) after irradiation to (a) 20 mGy, (b) 50 mGy, and (c) 100 mGy. Gene expression results are presented in terms of the base-2 logarithm of the RQ; positive and negative values represent increased and decreased gene expression level, respectively. Each point represents the mean of four individual experiments and error bars show the S.E
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4471643&req=5

Figure 2: Effect of elapsed time on relative quantification (RQ) after irradiation to (a) 20 mGy, (b) 50 mGy, and (c) 100 mGy. Gene expression results are presented in terms of the base-2 logarithm of the RQ; positive and negative values represent increased and decreased gene expression level, respectively. Each point represents the mean of four individual experiments and error bars show the S.E
Mentions: In this study, the effect of elapsed time following exposure was also examined. Early down-regulation of BAX gene expression induced by 20, 50, and 100 mGy, 4 hours following irradiation is shown in Figure 2a–c. This phenomenon was terminated 168 hours after delivery of 20 and 50 mGy. Maximum reduction in BAX gene expression was observed 4 hours following to 20 and 100 mGy [Figure 2a and b], similar result was observed 24 hours after 50 mGy [Figure 2c]. Low doses of gamma gave rise to up-regulation of Bcl-2 expression. The highest increase was noticed at 72 hours following to 50 mGy [Figure 2b], this was also true for delivery of 100 mGy at 24 hours after irradiation [Figure 2c].

Bottom Line: In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated.Modification of these gene expressions seems to be a principle pathway in the early radioresistance response.In our study, we found that these changes were temporary and faded completely within a week.

View Article: PubMed Central - PubMed

Affiliation: Medical Physics Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

ABSTRACT
Lymphocytes have demonstrated complex molecular responses to induced stress by ionizing radiation. Many of these reactions are mediated through modifications in gene expressions, including the genes involved in apoptosis. The primary aim of this study was to assess the effects of low doses of ionizing radiation on the apoptotic genes, expression levels. The secondary goal was to estimate the time-effect on the modified gene expression caused by low doses of ionizing radiation. Mononuclear cells in culture were exposed to various dose values ranged from 20 to 100 mGy by gamma rays from a Cobalt-60 source. Samples were taken for gene expression analysis at hours 4, 24, 48, 72, and 168 following to exposure. Expression level of two apoptotic genes; BAX (pro-apoptotic) and Bcl-2 (anti-apoptotic) were examined by relative quantitative real-time polymerase chain reaction (PCR), at different time intervals. Radio-sensitivity of peripheral blood mononucleated cells (PBMCs) was measured by the Bcl-2/BAX ratio (as a predictive marker for radio-sensitivity). The non-parametric two independent samples Mann-Whitney U-test were performed to compare means of gene expression. The results of this study revealed that low doses of gamma radiation can induce early down-regulation of the BAX gene of freshly isolated human PBMCs; however, these changes were restored to near normal levels after 168 hours. In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated. Four hours following to exposure to low doses of gamma radiation, apoptotic gene expression is modified, this is manifested as adaptive response. Modification of these gene expressions seems to be a principle pathway in the early radioresistance response. In our study, we found that these changes were temporary and faded completely within a week.

No MeSH data available.


Related in: MedlinePlus