Wang Qing-Qing, Zhang Zhi-Yi, Xiao Jian-Yong, Yi Chun, Li Lin-Zi, Huang Yan, Yun Jing-Ping
Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
Chin J Cancer. 2011 Dec;30(12):853-60. doi: 10.5732/cjc.011.10362. Epub 2011 Nov 18.
Nucleophosmin/B23 (NPM) is a universally expressed nucleolar phosphoprotein that participates in proliferation, apoptosis, ribosome assembly, and centrosome duplication; however, the role of NPM in cell cycle regulation is not well characterized. We investigated the mechanism by which NPM is involved in cell cycle regulation. NPM was knocked down using siRNA in HepG2 hepatoblastoma cells. NPM translocation following actinomycin D (ActD) treatment was investigated using immunofluorescent staining. Expression of NPM and other factors involved in cell cycle regulation was examined by Western blotting. Cell cycle distribution was measured using flow cytometry to detect 5-ethynyl-2'-deoxyuridine (EdU) incorporation. Cell proliferation was quantified by the MTT assay. Knockdown of NPM increased the percentage of HepG2 cells in S phase and led to decreased expression of P53 and P21Cip1/WAF1. S-phase arrest in HepG2 cells was significantly enhanced by ActD treatment. Furthermore, knockdown of NPM abrogated ActD-induced G2/M phase cell cycle arrest. Taken together, these data demonstrate that inhibition of NPM has a significant effect on the cell cycle.
核仁磷酸蛋白/B23（NPM）是一种广泛表达的核仁磷蛋白，参与细胞增殖、凋亡、核糖体组装和中心体复制；然而，NPM在细胞周期调控中的作用尚未得到充分阐明。我们研究了NPM参与细胞周期调控的机制。在肝癌细胞系HepG2中使用小干扰RNA（siRNA）敲低NPM。通过免疫荧光染色研究放线菌素D（ActD）处理后NPM的易位情况。通过蛋白质免疫印迹法检测NPM及其他参与细胞周期调控的因子的表达。使用流式细胞术检测5-乙炔基-2'-脱氧尿苷（EdU）掺入量来测量细胞周期分布。通过MTT法对细胞增殖进行定量分析。敲低NPM可增加处于S期的HepG2细胞百分比，并导致P53和P21Cip1/WAF1表达降低。ActD处理显著增强了HepG2细胞的S期阻滞。此外，敲低NPM可消除ActD诱导的G2/M期细胞周期阻滞。综上所述，这些数据表明抑制NPM对细胞周期有显著影响。
