Departments of a Radiation Oncology.
d Department of Chemistry, Indiana University, Bloomington, Indiana.
Radiat Res. 2018 Aug;190(2):107-116. doi: 10.1667/RR15019.1. Epub 2018 May 15.
Enediynes are a highly cytotoxic class of compounds. However, metallation of these compounds may modulate their activation, and thus their cytotoxicity. We previously demonstrated that cytotoxicity of two different metalloenediynes, including (Z)-N,N'-bis[1-pyridyl-2-yl-meth-(E)-ylidene]octa-4-ene-2,6-diyne-1,8-diamine] (PyED), is potentiated when the compounds are administered to HeLa cells during hyperthermia treatment at concentrations that are minimally or not cytotoxic at 37°C. In this study, we further characterized the concentration, time and temperature dependence of cytotoxicity of PyED on human U-1 melanoma cells. We also investigated the potential mechanisms by which PyED cytotoxicity is enhanced during hyperthermia treatment. Cell killing with PyED was dependent on concentration, temperature during treatment and time of exposure. Potentiation of cytotoxicity was observed when cells were treated with PyED at temperatures ≥39.5°C, and enhancement of cell killing increased with temperature and with increasing time at a given temperature. All cells treated with PyED were shown to have DNA damage, but substantially more damage was observed in cells treated with PyED during heating. DNA repair was also inhibited in cells treated with the drug during hyperthermia. Thus, potentiation of PyED cytotoxicity by hyperthermia may be due to enhancement of drug-induced DNA lesions, and/or the inhibition of repair of sublethal DNA damage. While the selective thermal activation of PyED supports the potential clinical utility of metalloenediynes as cancer thermochemotherapeutic agents, therapeutic gain could be optimized by identifying compounds that produce minimal toxicity at 37°C but which become activated and show enhancement of cytotoxicity within a tumor subjected to localized hyperthermic or thermal ablative treatment, or which might act as bifunctional agents. We thus also describe the development and initial characterization of a novel cofactor complex of PyED, platinated PyED (Pt-PyED). Pt-PyED binds to DNA-like cisplatin, and much like PyED, cytotoxicity is greatly enhanced after treatment with the drug at elevated temperatures. However, in contrast to PyED, Pt-PyED is only minimally cytotoxic at 37°C, at concentrations at which cytotoxicity is enhanced by hyperthermia. Further development of cisplatin-based enediynes may result in compounds which, when activated, will possess multiple DNA binding modalities similar to cisplatin, but produce less side effects in tissues at normothermic temperatures.
烯二炔类化合物是一类具有高细胞毒性的化合物。然而，这些化合物的金属化可能会调节它们的激活，从而影响它们的细胞毒性。我们之前的研究表明，两种不同的金属烯二炔化合物，包括（Z）-N，N'-双[1-吡啶-2-基-甲-（E）-亚乙基]辛-4-烯-2,6-二炔-1,8-二胺]（PyED），在浓度下用金属化的烯二炔化合物处理 HeLa 细胞，然后在 37°C 下进行高温治疗，会增强其细胞毒性，而在 37°C 下该浓度不会产生细胞毒性或仅有轻微细胞毒性。在这项研究中，我们进一步研究了 PyED 对人 U-1 黑素瘤细胞的浓度、时间和温度依赖性细胞毒性。我们还研究了在高温治疗过程中增强 PyED 细胞毒性的潜在机制。PyED 的细胞杀伤作用取决于浓度、治疗过程中的温度和暴露时间。当细胞在≥39.5°C 的温度下用 PyED 处理时，观察到细胞毒性的增强，并且随着温度的升高和在给定温度下的时间的增加，细胞杀伤作用增强。用 PyED 处理的所有细胞都显示出 DNA 损伤，但在加热过程中用 PyED 处理的细胞中观察到的损伤明显更多。在用药物处理的细胞中，DNA 修复也受到抑制。因此，高温增强 PyED 细胞毒性可能是由于增强了药物诱导的 DNA 损伤，和/或抑制了亚致死性 DNA 损伤的修复。虽然金属烯二炔的选择性热激活支持其作为癌症热化疗剂的潜在临床应用，但通过确定在 37°C 时毒性最小但在局部高温或热消融治疗下被激活并表现出增强的细胞毒性的化合物，或者可能作为双功能剂，治疗增益可以得到优化。因此，我们还描述了 PyED 的新型辅助因子复合物，铂化 PyED（Pt-PyED）的开发和初步特征。Pt-PyED 与类似顺铂的 DNA 结合，并且与 PyED 非常相似，在升高的温度下用药物处理后，细胞毒性大大增强。然而，与 PyED 不同的是，Pt-PyED 在 37°C 时的细胞毒性仅略有降低，而在高温下，细胞毒性增强。顺铂类烯二炔的进一步发展可能会产生具有类似顺铂的多种 DNA 结合模式的化合物，但在正常体温下的组织中产生较少的副作用。
