Zhao Shiguang, Tsuchida Takahiro, Kawakami Katsuhiro, Shi Changbin, Kawamoto Keiji
Department of Neurosurgery, Kansai Medical University, Moriguchi city, Osaka 570-8506, Japan.
Int J Oncol. 2002 Jul;21(1):49-55.
Recent clinical studies have demonstrated that As2O3 is an effective drug in the treatment of acute promyelocytic leukemia (APL) by inducing apoptosis and inhibiting the proliferation of leukemia cells both in vitro and in vivo. As a novel anticancer agent for the treatment of solid cancer, As2O3 is promising, but no experimental investigations of its efficacy on glioblastoma have been conducted at concentrations that may be achieved clinically. In addition, the cell proliferation and cell cycle regulating mechanism of As2O3 has not yet to be clarified, especially in solid cancers. We investigated the effect of As2O3 on proliferation and cell cycle regulation with change in cyclins in two human glioblastoma cell lines differing in p53 status (U87MG-wt; T98G-mutated). Sensitivity to As2O3 varied depending on the dose with the IC50 of the U87MG and T98G cells being 1.78 and 3.55 microM, respectively. Analysis by laser scanning cytometry (LSC) indicated that As2O3 inhibited the proliferation of the two cell lines via cell cycle arrest both at the G1 and G2 phases. To address the mechanism of the antiproliferative effect of As2O3, we examined its effect on cell cycle-related proteins by means of LSC, confocal microscopy and Western blot analysis. As2O3 induced an increase in p53 level and a decrease in level of cyclin B1 combined with cell arrest at G2/M in both cell lines. Cell arrest in G1, however, was associated with a decline in cyclin D1 expression only in the wt U87MG cells. As2O3 also induced apoptosis of U87MG cells as evidenced by the presence of cells with fractional DNA content ( cell populations). The present evidence that As2O3 at relatively low concentration effectively inhibited proliferation of U87MG and T98G cells in vitro, suggests that the drug may be considered for in vivo testing on animal models and possibly clinical trials on glioma patients.
近期临床研究表明，三氧化二砷（As2O3）是治疗急性早幼粒细胞白血病（APL）的一种有效药物，它可在体内外诱导白血病细胞凋亡并抑制其增殖。作为一种用于治疗实体癌的新型抗癌药物，As2O3很有前景，但尚未针对其在临床可能达到的浓度下对胶质母细胞瘤的疗效进行实验研究。此外，As2O3的细胞增殖和细胞周期调节机制尚未阐明，尤其是在实体癌中。我们研究了As2O3对两种p53状态不同的人胶质母细胞瘤细胞系（U87MG-wt；T98G-突变型）增殖和细胞周期调节的影响以及细胞周期蛋白的变化。对As2O3的敏感性因剂量而异，U87MG和T98G细胞的IC50分别为1.78和3.55微摩尔。激光扫描细胞术（LSC）分析表明，As2O3通过使细胞周期停滞在G1期和G2期来抑制这两种细胞系的增殖。为了探究As2O3抗增殖作用的机制，我们通过LSC、共聚焦显微镜和蛋白质免疫印迹分析研究了其对细胞周期相关蛋白的影响。As2O3在两种细胞系中均诱导p53水平升高和细胞周期蛋白B1水平降低，并伴有细胞停滞在G2/M期。然而，仅在野生型U87MG细胞中，G1期的细胞停滞与细胞周期蛋白D1表达下降有关。As2O3还诱导了U87MG细胞凋亡，表现为出现DNA含量分数的细胞（细胞群体）。目前有证据表明，相对低浓度的As2O3在体外可有效抑制U87MG和T98G细胞的增殖，这表明该药物可考虑用于动物模型的体内试验以及可能的胶质瘤患者临床试验。
