Treeck Oliver, Wackwitz Birgit, Haus Ulrike, Ortmann Olaf
Department of Obstetrics and Gynecology, University Regensburg, Caritas Hospital St. Josef, Landshuter Strasse 65, 93053 Regensburg, Germany.
Gynecol Oncol. 2006 Aug;102(2):292-9. doi: 10.1016/j.ygyno.2005.12.019. Epub 2006 Jan 26.
Interactions between estrogen receptor signaling and the PI3K/Akt pathway are present in estrogen-dependent cancer cells. Therapeutical inhibition of each of these pathways has been proven to exert antitumoral effects. Inhibition of mammalian target of rapamycin (mTOR), a downstream target of Akt, is able to restore tamoxifen response in tamoxifen-resistant breast cancer cells. Given that Akt and mTOR phosphorylation also is frequently detected in ovarian and endometrial cancer, we intended to find out to what extent mTOR inhibitor RAD001 (everolimus) and tamoxifen add to each other's effects on growth and apoptosis of cancer cell lines derived from these tissues when given concomitantly.
OVCAR-3 and SK-OV-3 ovarian cancer cells, HEC-1A endometrial adenocarcinoma cells and MCF-7 breast cancer cells were treated with different concentrations of mTOR inhibitor RAD001 alone or in combination with 4-OH tamoxifen. Relative numbers of viable cells were assessed by means of the resazurin-based Cell Titer Blue assay, cellular apoptosis was examined by measurement of activated caspases 3 and 7 by means of the luminometric Caspase-Glo assay.
Treatment with RAD001 resulted in growth inhibition of all employed cancer cell lines in a dose-dependent manner, and SK-OV-3 ovarian cancer cells proved to be most sensitive to this drug. Moreover, we report the observation of additive, but not synergistical growth inhibitory effects of a combination treatment with RAD001 and 4-OH TAM on SK-OV-3 and OVCAR-3 ovarian cancer cells and MCF-7 breast cancer cells in vitro, whereas no such effect was observed in HEC-1A endometrial adenocarcinoma cells. Combination treatment with both drugs was demonstrated to be superior to single treatment with lower concentrations (0.1 and 1 nM) of RAD001 or standard concentrations of 4-OH TAM. Furthermore, RAD001 increased the apoptotic effect triggered by high 4-OH TAM concentrations in SK-OV-3 ovarian cancer cells.
Combination treatment with RAD001 and 4-OH TAM in vitro exerts an additive antitumoral effect on ovarian cancer cells and MCF-7 breast cancer cells. The significance of these data in the clinical situation has to be evaluated in further studies.
雌激素受体信号传导与PI3K/Akt通路之间的相互作用存在于雌激素依赖性癌细胞中。已证实对这些通路中的每一条进行治疗性抑制均能发挥抗肿瘤作用。抑制雷帕霉素哺乳动物靶点（mTOR），即Akt的下游靶点，能够恢复他莫昔芬耐药乳腺癌细胞对他莫昔芬的反应。鉴于在卵巢癌和子宫内膜癌中也经常检测到Akt和mTOR磷酸化，我们旨在探究mTOR抑制剂RAD001（依维莫司）和他莫昔芬同时给药时，对源自这些组织的癌细胞系的生长和凋亡的相互影响程度。
用不同浓度的mTOR抑制剂RAD001单独或与4-羟基他莫昔芬联合处理OVCAR-3和SK-OV-3卵巢癌细胞、HEC-1A子宫内膜腺癌细胞和MCF-7乳腺癌细胞。通过基于刃天青的细胞活力蓝检测法评估活细胞的相对数量，通过发光法半胱天冬酶-活力检测法测量活化的半胱天冬酶3和7来检测细胞凋亡。
RAD001处理以剂量依赖性方式抑制所有所用癌细胞系的生长，并且SK-OV-3卵巢癌细胞对该药物最为敏感。此外，我们报告了在体外，RAD001与4-羟基他莫昔芬联合处理对SK-OV-3和OVCAR-3卵巢癌细胞以及MCF-7乳腺癌细胞具有相加而非协同的生长抑制作用，而在HEC-1A子宫内膜腺癌细胞中未观察到这种作用。两种药物联合处理被证明优于用较低浓度（0.1和1 nM）的RAD001或标准浓度的4-羟基他莫昔芬进行单一处理。此外，RAD001增强了高浓度4-羟基他莫昔芬在SK-OV-3卵巢癌细胞中引发的凋亡效应。
在体外，RAD001与4-羟基他莫昔芬联合处理对卵巢癌细胞和MCF-7乳腺癌细胞具有相加的抗肿瘤作用。这些数据在临床情况中的意义有待进一步研究评估。
