中文摘要：

目的研究let-7和miR-24在紫外线B（UVB）诱导的细胞凋亡中的可能作用。方法NIH3T3细胞受50J／m^2 UVB照射后，用Hoechest33342／PI染色观察其凋亡情况；RT-PCR检测let-7和miR-24的表达水平。利用在线数据库PicTar等预测它们的靶基因，并用GOstat软件对这些靶基因进行功能分类。结果荧光显微镜下，NIH3T3细胞经UVB照射后可见典型的凋亡和坏死细胞；let-7和miR-24在UVB照射组的表达水平较对照组明显增加。用GOstat进行功能分类后发现，casp3、bcl212、map3kl和cdk5等基因同时也是UVB诱导的细胞周期调节的靶基因。结论let-7和miR-24可能参与UVB诱导的细胞凋亡。

英文摘要：

Objective To study the function of let-7 and miR-24 in UVB-indueed apoptosis. Methods After NIH3T3 cells were irradiated with UVB, Hoechest33342/PI staining was used to study the cell apoptosis and RT-PCR was used to uralyzc the expression level of let-7 and miR-24. In addition, potential target genes of these miRNAs in PieTar were classified into different function categories through GOstat software. Results Compared to the control, the NIH3T3 ceils exposure to UVB appeared typical apoptotic and necrotic cells by fluorescence microscope. The expression level of let-7 and miR-24 in NIH3T3 cells after UVB irradiation was higher than that of the control. Among the target genes, casp3,bcl212, map3kl and cdk5 were also involved in UVB-induced apoptosis mechanism. Conclusion Let-7 and miR-24 play a role in UVB-induced apoptosis.