MiR-34a is up-regulated in response to low dose, low energy X-ray induced DNA damage in breast cells.
MiR-34a is up-regulated in response to low dose, low energy X-ray induced DNA damage in breast cells.
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DOI：
10.1186/1748-717x-8-231
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发表时间：
2013-10-05
期刊：
影响因子：
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通讯作者：
de Moura Gallo CV
中科院分区：
文献类型：
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作者：
Stankevicins L;Almeida da Silva AP;Ventura Dos Passos F;Dos Santos Ferreira E;Menks Ribeiro MC;G David M;J Pires E;Ferreira-Machado SC;Vassetzky Y;de Almeida CE;de Moura Gallo CV
MicroRNA是参与基因表达调控的非编码RNA，包括DNA损伤反应。低剂量的低能X射线辐射，类似于乳房X光检查中使用的辐射，已被描述为具有遗传毒性。在目前的工作中，我们研究了miR-34 a的表达;这是一种描述良好的p53调控的miRNA，与低剂量X射线照射的细胞反应有关。非癌性乳腺细胞系MCF-10 A和癌性T-47 D和MCF-7细胞系接受使用5戈伊剂量的低能量X射线照射（范围为28-30 Kv）。在照射后4和24小时通过qRT-PCR评估miR-34 a、let-7a和miR-21的表达水平。然后在MCF-10A和MCF-7细胞系中通过彗星试验和微核估计来测量DNA损伤，其中在照射后可以观察到miR-34 a水平的增加。细胞核染色和荧光显微镜观察凋亡细胞率。这些实验也在MCF-10A和MCF-7细胞系中以低剂量（3、12和48 mGy）进行。我们已经观察到在5戈伊照射后4小时，MCF-10 A和MCF-7细胞系中miR-34 a表达增加，而其水平在T-47 D（一种携带非功能性p53的乳腺癌细胞系）中没有变化。在低剂量下，与MCF-7相比，miR-34 a在非肿瘤MCF-10A中上调的程度更高。MiR-34 a水平在照射后24小时降低。我们还观察到在低剂量和高剂量的低能量X射线照射下，相对于模拟对照，照射后4小时和24小时的MCF-10A和MCF-7中的DNA损伤和凋亡。低能X射线可促进DNA链断裂，miR-34 a可能参与低能X射线对细胞DNA损伤的反应。MiR-34 a表达与X射线剂量、照射后时间和细胞类型相关。本研究加强了调查低剂量X射线照射乳腺细胞的后果的必要性。
MicroRNAs are non-coding RNAs involved in the regulation of gene expression including DNA damage responses. Low doses of low energy X-ray radiation, similar to those used in mammographic exams, has been described to be genotoxic. In the present work we investigated the expression of miR-34a; a well described p53-regulated miRNA implicated in cell responses to X-ray irradiation at low doses. Non-cancerous breast cell line MCF-10A and cancerous T-47D and MCF-7 cell lines were submitted to a low-energy X-ray irradiation (ranging from 28–30 Kv) using a dose of 5 Gy. The expression level of miR-34a, let-7a and miR-21 was assessed by qRT-PCR at 4 and 24 hours post-irradiation. DNA damage was then measured by comet assay and micronuclei estimation in MCF-10A and MCF-7 cell lines, where an increase of miR-34a levels could be observed after irradiation. The rate of apoptotic cells was estimated by nuclear staining and fluorescence microscopy. These experiments were also performed at low doses (3; 12 and 48 mGy) in MCF-10A and MCF-7 cell lines. We have observed an increase in miR-34a expression 4 hours post-irradiation at 5 Gy in MCF-10A and MCF-7 cell lines while its level did not change in T-47D, a breast cancer cell line bearing non-functional p53. At low doses, miR-34a was up-regulated in non-tumoral MCF-10A to a higher extent as compared to MCF-7. MiR-34a levels decreased 24 hours post-irradiation. We have also observed DNA damage and apoptosis at low-energy X-ray irradiation at low doses and the high dose in MCF-10A and MCF-7 4 and 24 hours post-irradiation relative to the mock control. Low energy X-ray is able to promote DNA strand breaks and miR-34a might be involved in cell responses to low energy X-ray DNA damage. MiR-34a expression correlates with X-ray dose, time after irradiation and cell type. The present study reinforces the need of investigating consequences of low dose X-ray irradiation of breast cells.