Department of Pathology, the School of Stomatology, Shandong University, Ji-nan, China.
Acta Pharmacol Sin. 2011 Feb;32(2):253-8. doi: 10.1038/aps.2010.208.
To investigate the effect of the growth arrest- and DNA damage-inducible Gadd45a gene on the radiosensitivity of human tongue squamous cell carcinoma cell line to ionizing radiation (IR).
Short interfering ribonucleic acid (si-RNA) targeting Gadd45a or an irrelevant mRNA (nonsense si-RNA) was chemically synthesized. The constructed si-RNAs were transfected into Tca8113 cells and Gadd45a expression was determined using quantitative real-time PCR and Western-blot. After 24-h exposure to IR at a dose rate of 4 Gy/min, apoptosis of Tca8113 cells was detected using flow cytometry, and radiosensitivity was measured using MTT assays.
IR apparently increased the expression of Gadd45a at mRNA and protein levels in Tca8113 cells. The effect was efficiently inhibited by transfection with Gadd45a si-RNA (P<0.01). Furthermore, silencing Gadd45a gene significantly increased cell viability and decreased the percentage of apoptotic cells during irradiation, which indicated that IR-induced Gadd45a over-expression could increase the radiosensitivity of Tca8113 cells.
These results indicated that targeting Gadd45a may have important therapeutic implications in sensitizing Tca8113 cells to IR.
研究生长停滞和 DNA 损伤诱导基因 Gadd45a 对人舌鳞癌细胞系电离辐射（IR）敏感性的影响。
化学合成靶向 Gadd45a 的短发夹 RNA（si-RNA）或无关 mRNA（无意义 si-RNA）。将构建的 si-RNAs 转染至 Tca8113 细胞中，并用定量实时 PCR 和 Western-blot 检测 Gadd45a 的表达。在 4 Gy/min 的剂量率下暴露于 IR 24 h 后，用流式细胞术检测 Tca8113 细胞的凋亡，并用 MTT 法测量放射敏感性。
IR 明显增加了 Tca8113 细胞中 Gadd45a 在 mRNA 和蛋白水平的表达。用 Gadd45a si-RNA 转染可有效抑制该作用（P<0.01）。此外，沉默 Gadd45a 基因在照射过程中显著增加了细胞活力并降低了凋亡细胞的百分比，这表明 IR 诱导的 Gadd45a 过表达可增加 Tca8113 细胞的放射敏感性。
这些结果表明，靶向 Gadd45a 可能对 Tca8113 细胞对 IR 增敏具有重要的治疗意义。
