Yin F, Giuliano A E, Law R E, Van Herle A J
Division of Endocrinology, UCLA School of Medicine, Los Angeles, California 90024, USA.
Anticancer Res. 2001 Jan-Feb;21(1A):413-20.
We have previously reported that apigenin inhibits the growth of thyroid cancer cells by attenuating epidermal growth factor receptor (EGF-R) tyrosine phosphorylation and phosphorylation of ERK mitogen-activated protein (MAP) kinase. In this study, we assessed the growth inhibitory effect of apigenin on MCF-7 breast carcinoma cells that express two key cell cycle regulators, wild-type p53 and the retinoblastoma tumor suppressor protein (Rb), and MDA-MB-468 breast carcinoma cells that are mutant for p53 and Rb negative. We found that apigenin potently inhibited growth of both MCF-7 and MDA-MB-468 breast carcinoma cells. The approximate IC50 values determined after 3 days incubation, were 7.8 micrograms/ml for MCF-7 cells, and 8.9 micrograms/ml for MDA-MB-468 cells, respectively. Because the cell cycle studies using FACS showed that both MCF-7 and MDA-MB-468 cells were arrested in G2/M phase after apigenin treatment, we studied the effects of apigenin on cell cycle regulatory molecules. We observed that G2/M arrest by apigenin involved a significant decrease in cyclin B1 and CDK1 protein levels, resulting in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and CDK6 protein expression. In MCF-7 cells, apigenin markedly reduced Rb phosphorylation after 12 h. We also found that apigenin treatment resulted in a dose- and time-dependent inhibition of ERK MAP kinase phosphorylation and activation in MDA-MB-468 cells. These results suggest that apigenin is a promising antibreast cancer agent and its growth inhibitory effects are mediated by targeting different signal transduction pathways in MCF-7 and MDA-MB-468 breast carcinoma cells.
我们之前曾报道过，芹菜素通过减弱表皮生长因子受体（EGF-R）酪氨酸磷酸化以及ERK丝裂原活化蛋白（MAP）激酶的磷酸化来抑制甲状腺癌细胞的生长。在本研究中，我们评估了芹菜素对表达两种关键细胞周期调节因子（野生型p53和视网膜母细胞瘤肿瘤抑制蛋白（Rb））的MCF-7乳腺癌细胞以及p53突变且Rb阴性的MDA-MB-468乳腺癌细胞的生长抑制作用。我们发现芹菜素能有效抑制MCF-7和MDA-MB-468乳腺癌细胞的生长。孵育3天后测定的近似IC50值，MCF-7细胞为7.8微克/毫升，MDA-MB-468细胞为8.9微克/毫升。由于使用流式细胞术进行的细胞周期研究表明，芹菜素处理后MCF-7和MDA-MB-468细胞均停滞在G2/M期，我们研究了芹菜素对细胞周期调节分子的影响。我们观察到芹菜素引起的G2/M期停滞涉及细胞周期蛋白B1和CDK1蛋白水平的显著降低，从而导致CDK1激酶活性受到明显抑制。芹菜素降低了CDK4、细胞周期蛋白D1和A的蛋白水平，但不影响细胞周期蛋白E、CDK2和CDK6的蛋白表达。在MCF-7细胞中，芹菜素在12小时后显著降低了Rb的磷酸化水平。我们还发现芹菜素处理导致MDA-MB-468细胞中ERK MAP激酶的磷酸化和激活受到剂量和时间依赖性抑制。这些结果表明芹菜素是一种有前景的抗乳腺癌药物，其生长抑制作用是通过靶向MCF-7和MDA-MB-468乳腺癌细胞中不同的信号转导途径介导的。
