Janmaat Maarten L, Rodriguez José A, Jimeno José, Kruyt Frank A E, Giaccone Giuseppe
Department of Medical Oncology, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007MB Amsterdam, The Netherlands.
Mol Pharmacol. 2005 Aug;68(2):502-10. doi: 10.1124/mol.105.011361. Epub 2005 May 20.
Kahalalide F (KF) is a novel marine-derived antitumor agent that is currently undergoing phase II clinical trials. The mechanism of action of KF is not well understood. In line with previous reports, we show that KF caused rapid and potent cytotoxicity in the breast cancer cell lines SKBR3 and BT474, characterized by cytoplasmic swelling and DNA clumping. Several markers of caspase-dependent apoptosis, such as phosphatidyl-serine externalization, cytochrome c release, and caspase-3 and poly-(ADP-ribose) polymerase cleavage were negative after KF exposure. Inhibitors of caspases or cathepsins failed to protect against KF cytotoxicity. Altogether, these data indicate that KF-induced cell death is a necrosis-like process. The sensitivity to KF in a panel of human tumor cell lines derived from breast (SKBR3, BT474, and MCF7), vulval (A431), non-small-cell lung (H460, A549, SW1573, and H292), and hepatic (Skhep1, HepG2, and Hep3B) carcinomas positively correlated with ErbB3 (HER3) protein levels. A KF-resistant subline of colon carcinoma cells, HT29/KF, expressed significantly reduced levels of all ErbB receptors, but short-term KF exposure of sensitive cell lines such as SKBR3 selectively induced down-regulation of ErbB3. On the other hand, stable transfection of an ErbB3-expressing plasmid increased the KF sensitivity of H460 cells, the most resistant cell line in our panel. Finally, we found that KF efficiently inhibited the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway in sensitive cell lines and that ectopic expression of a constitutively active Akt mutant reduced KF cytotoxicity in this cell line. In summary, our results identify ErbB3 and the downstream PI3K-Akt pathway as important determinants of the cytotoxic activity of KF in vitro.
kahalalide F（KF）是一种新型的海洋来源抗肿瘤药物，目前正处于II期临床试验阶段。KF的作用机制尚不完全清楚。与之前的报道一致，我们发现KF在乳腺癌细胞系SKBR3和BT474中引起快速且强效的细胞毒性，其特征为细胞质肿胀和DNA聚集。KF处理后，几种半胱天冬酶依赖性凋亡标志物，如磷脂酰丝氨酸外翻、细胞色素c释放以及半胱天冬酶-3和聚（ADP-核糖）聚合酶的切割均为阴性。半胱天冬酶或组织蛋白酶抑制剂未能保护细胞免受KF的细胞毒性。总之，这些数据表明KF诱导的细胞死亡是一个类似坏死的过程。在一组源自乳腺癌（SKBR3、BT474和MCF7）、外阴癌（A431）、非小细胞肺癌（H460、A549、SW1573和H292）和肝癌（Skhep1、HepG2和Hep3B）的人类肿瘤细胞系中，对KF的敏感性与ErbB3（HER3）蛋白水平呈正相关。结肠癌细胞的KF耐药亚系HT29/KF表达的所有ErbB受体水平均显著降低，但敏感细胞系如SKBR3短期暴露于KF会选择性诱导ErbB3下调。另一方面，稳定转染表达ErbB3的质粒可增加H460细胞（我们研究组中最耐药的细胞系）对KF的敏感性。最后，我们发现KF可有效抑制敏感细胞系中的磷脂酰肌醇3激酶（PI3K）-Akt信号通路，并且组成型活性Akt突变体的异位表达可降低该细胞系中KF的细胞毒性。总之，我们的结果表明ErbB3和下游PI3K-Akt通路是KF体外细胞毒性活性的重要决定因素。
