Kurebayashi Junichi, Kanomata Naoki, Yamashita Tetsumasa, Shimo Toshiro, Moriya Takuya
Department of Breast and Thyroid Surgery, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan.
Department of Pathology 2, Kawasaki Medical School, Kurashiki, Okayama, 701-0192, Japan.
Breast Cancer. 2016 May;23(3):425-36. doi: 10.1007/s12282-014-0580-9. Epub 2015 Jan 1.
Eribulin mesylate (eribulin), a non-taxane microtubule dynamic inhibitor, has been widely used in the treatment of patients with advanced or metastatic breast cancer. The combined antitumor and anticancer stem cell (CSC) activities of eribulin with endocrine therapeutic agents have not yet been examined in breast cancer cells. We herein investigated the combined effects of eribulin and antiestrogens.
A panel of eight breast cancer cell lines, including five estrogen receptor (ER)-positive and three ER-negative cell lines, was used. These cells were treated with eribulin and/or the antiestrogen, 4-hydroxytamoxifen or fulvestrant. Their growth inhibitory activities and effects on cell cycle progression, apoptosis, and the CSC population were investigated. CSCs were detected using the CD44/CD24/EpCAM, Aldefluor, and mammosphere assays.
The 50% growth inhibitory concentrations of eribulin were 0.38-2.64 nM for the eight cell lines tested. Eribulin exhibited significant antitumor activity under estrogen-supplemented conditions in ER-positive breast cancer cells. The combined antitumor activity of eribulin with an antiestrogen was evaluated using the combination index. The combination index was 0.43-1.46 for ER-positive cell lines. The additive antitumor effect of eribulin with 4-OHT was only significant in MCF-7 cells. Eribulin induced the accumulation of G2/M and apoptosis, while antiestrogens induced the retardation of G1-S cell cycle and apoptosis, respectively. Estrogen markedly increased the proportion of CSCs, whereas antiestrogens inhibited increases in ER-positive cell lines. Moreover, eribulin decreased the proportion of CSCs in either ER-positive or ER-negative cell lines. The combined treatment of eribulin with an antiestrogen did not additively decrease the proportion of CSCs in ER-positive cell lines.
The results of the present study demonstrated that eribulin had potent antitumor effects on estrogen-stimulated ER-positive breast cancer cells and the combined treatment of eribulin with an antiestrogen resulted in a weakly additive antitumor effect. We herein suggested for the first time that eribulin exhibited anti-CSC effects on either ER-positive or ER-negative breast cancer cells.
甲磺酸艾瑞布林（艾瑞布林）是一种非紫杉烷类微管动力学抑制剂，已广泛应用于晚期或转移性乳腺癌患者的治疗。艾瑞布林与内分泌治疗药物联合的抗肿瘤和抗癌干细胞（CSC）活性尚未在乳腺癌细胞中进行研究。我们在此研究了艾瑞布林与抗雌激素药物的联合作用。
使用一组8种乳腺癌细胞系，包括5种雌激素受体（ER）阳性和3种ER阴性细胞系。这些细胞用艾瑞布林和/或抗雌激素药物4-羟基他莫昔芬或氟维司群处理。研究它们的生长抑制活性以及对细胞周期进程、凋亡和CSC群体的影响。使用CD44/CD24/EpCAM、醛脱氢酶和乳腺球测定法检测CSC。
在所测试的8种细胞系中，艾瑞布林的50%生长抑制浓度为0.38 - 2.64 nM。艾瑞布林在雌激素补充条件下对ER阳性乳腺癌细胞表现出显著的抗肿瘤活性。使用联合指数评估艾瑞布林与抗雌激素药物的联合抗肿瘤活性。ER阳性细胞系的联合指数为0.43 - 1.46。艾瑞布林与4-羟基他莫昔芬的相加抗肿瘤作用仅在MCF-7细胞中显著。艾瑞布林诱导G2/M期积累和凋亡，而抗雌激素药物分别诱导G1-S期细胞周期阻滞和凋亡。雌激素显著增加CSC的比例，而抗雌激素药物在ER阳性细胞系中抑制这种增加。此外，艾瑞布林在ER阳性或ER阴性细胞系中均降低CSC的比例。艾瑞布林与抗雌激素药物的联合治疗在ER阳性细胞系中并未相加降低CSC的比例。
本研究结果表明，艾瑞布林对雌激素刺激的ER阳性乳腺癌细胞具有强大的抗肿瘤作用，且艾瑞布林与抗雌激素药物的联合治疗产生了微弱的相加抗肿瘤作用。我们在此首次表明，艾瑞布林对ER阳性或ER阴性乳腺癌细胞均表现出抗CSC作用。
