ter Haar E, Hamel E, Balachandran R, Day B W
Department of Environmental and Occupational Health, University of Pittsburgh, Pennsylvania 15238, USA.
Anticancer Res. 1997 May-Jun;17(3C):1861-9.
Z-1,1-dichloro-2,3-diphenylcyclopropane (a.k.a. Analog II, AII) is a known anti-breast cancer agent with apparent antiestrogenic effects and remarkably low toxicity in rodents. We have recently shown that AII and its major metabolite Z-alpha-chlorochalcone (ZCC) inhibit proliferation of both estrogen-responsive and -nonresponsive human breast cancer cells, suggesting its mechanism is not mediated by the type I estrogen receptor (ER). The present studies were performed to begin to define the molecular targets of AII and ZCC. Based on the compounds' structures and actions, we hypothesized that their effects could be due to interaction at type II estrogen binding sites (EBSII) and/or cellular microtubules. The affinities of AII ZCC and the positive control diethylstilbestrol (DES) for the ER (in MCF-7 and MCF-7/LY2 cells) and EBSII (in MCF-7, MCF 7/LY2, and MDA-MB231 cells) were determined with a whole cell assay for displacement of [3H]estradiol. The kinetics of their effects on cellular microtubules and cell cycle distribution of human breast cancer cells were measured by indirect immunofluorescence and flow cytometry. Their abilities to inhibit assembly of isolated tubulin in vitro were determined. AII, ZCC, and DES had similar affinities for the EBSII in the three cell lines. Neither AII nor ZCC displaced [3H]estradiol from the ER in MCF-7 cells, whereas DES did. The microtubule network of MDA-MB231 cells exposed to 100 microM AII or 10 microM ZCC began to disassemble within 1 hour of treatment and was completely diffuse after 6 hour of exposure to either drug. AII inhibited in vitro assembly of tubulin, with an IC50 of 6.7 +/- 0.9 microM, while ZCC was inactive below 40 microM. Both drugs caused accumulation of the cells in the G2/M phase of the cell cycle. The evidence suggests that the antitumor action of AII is mediated, at least in part, through the EBSII and/or perturbation of tubulin-microtubule dynamics. AII thus represents a new lead compound for design and discovery of novel antitumor agents directed against the EBSII and/or microtubules.
Z-1,1-二氯-2,3-二苯基环丙烷（又称类似物II，AII）是一种已知的抗乳腺癌药物，在啮齿动物中具有明显的抗雌激素作用且毒性极低。我们最近发现，AII及其主要代谢产物Z-α-氯查耳酮（ZCC）可抑制雌激素反应性和非反应性人乳腺癌细胞的增殖，这表明其作用机制不是由I型雌激素受体（ER）介导的。进行本研究以开始确定AII和ZCC的分子靶点。基于这些化合物的结构和作用，我们推测它们的作用可能是由于与II型雌激素结合位点（EBSII）和/或细胞微管相互作用所致。通过全细胞试验测定AII、ZCC和阳性对照己烯雌酚（DES）对ER（在MCF-7和MCF-7/LY2细胞中）和EBSII（在MCF-7、MCF 7/LY2和MDA-MB231细胞中）的亲和力，以置换[3H]雌二醇。通过间接免疫荧光和流式细胞术测量它们对人乳腺癌细胞的细胞微管和细胞周期分布的影响动力学。测定它们在体外抑制分离微管蛋白组装的能力。AII、ZCC和DES在三种细胞系中对EBSII具有相似的亲和力。在MCF-7细胞中，AII和ZCC均未从ER上置换[3H]雌二醇，而DES可以。暴露于100 microM AII或10 microM ZCC的MDA-MB231细胞的微管网络在处理后1小时内开始解体，在暴露于任何一种药物6小时后完全分散。AII抑制微管蛋白的体外组装（IC50为6.7±0.9 microM），而ZCC在40 microM以下无活性。两种药物均导致细胞在细胞周期的G2/M期积累。证据表明，AII的抗肿瘤作用至少部分是通过EBSII和/或微管蛋白-微管动力学的扰动介导的。因此，AII代表了一种新的先导化合物，用于设计和发现针对EBSII和/或微管的新型抗肿瘤药物。
