MicroRNA-223 Enhances Radiation Sensitivity of U87MG Cells In聽Vitro and In聽Vivo by Targeting Ataxia Telangiectasia Mutated

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• 作者：Liping Liang ; MD^&lowast ; ; Ji Zhu ; MD ; PhD^&lowast ; ; Nicholas G. Zaorsky ; MD^&dagger ; ; Yun Deng ; MD^&lowast ; ; Xingzhong Wu ; PhD^&Dagger ; ; Yong Liu ; PhD^&lowast ; ; Fangqi Liu ; MD^§ ; ; Guoxiang Cai ; MD ; PhD^§ ; ; Weilie Gu ; MD^§ ; ; Lijun Shen ; MD^&lowast ; ; Zhen Zhang ; MD ; PhD^&lowast ; ; ^{zhenzhang6@hotmail.com" class="auth_mail}
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：15 March, 2014
• 年：2014
• 卷：88
• 期：4
• 页码：955-960
• 全文大小：1041 K

文摘

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Purpose

Ataxia telangiectasia mutated (ATM) protein is important in the DNA damage response because it repairs radiation-induced damage in cancers. We examined the effect of microRNA-223 (miR-223), a regulator of ATM expression, on radiation sensitivity of cancer cells.

Methods and Materials

Human embryonic kidney 293聽T (293T) cells were infected with pLL3.7-miR-223 plasmid to generate the pLL3.7-miR-223 and -empty virus (EV) lentivirus (miR-223 and EV). A dual luciferase assay in which the reporter contained wild-type 3鈥?untranslated region (UTR) of ATM was performed. U87MG聽cells were infected with miR-223 or EV to establish the overexpressed stable cell lines (U87-223 or U87-EV, respectively). Cells were irradiated in聽vitro, and dose enhancement ratios at 2聽Gy (DER₂) were calculated. Hind legs of BALB/c athymic mice were injected with U87-223 or U87-EV cells; after 2聽weeks, half of the tumors were irradiated. Tumor volumes were tracked for a total of 5聽weeks.

Results

The dual luciferase reporter assay showed a significant reduction in luciferase activity of 293T cells cotransfected with miR-223 and the ATM 3鈥睻TR compared to that in EV control. Overexpression of miR-223 in U87MG聽cells showed that ATM expression was significantly downregulated in the U87-223聽cells compared to that in U87-EV (ATM/尾-actin mRNA 1.0 vs 1.5, P<.05). U87-223聽cells were hypersensitive to radiation compared to U87-EV cells in聽vitro (DER₂聽=聽1.32, P<.01). Mice injected with miR-223-expressing tumors had almost the same tumors after 3聽weeks (1.5聽cm³ vs 1.7聽cm³). However, irradiation significantly decreased tumor size in miR-223-expressing tumors compared to those in controls (0.033聽cm³ vs 0.829聽cm³).

Conclusions

miR-223 overexpression downregulates ATM expression and sensitizes U87聽cells to radiation in聽vitro and in聽vivo. MicroRNA-223 may be a novel cancer-targeting therapy, although its cancer- and patient-specific roles are currently undefined.