Dick Ryan A, Yu Xiang, Kensler Thomas W
Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA.
Clin Cancer Res. 2004 Feb 15;10(4):1492-9. doi: 10.1158/1078-0432.ccr-03-0162.
Illudins S and M are extremely cytotoxic products of the fungus Omphalotus illudens. They were evaluated as possible anticancer chemotherapeutic agents but displayed unfavorable therapeutic indices. Irofulven (6-hydroxymethylacylfulvene), a less toxic, synthetic derivative of illudin S, has proven very effective in many preclinical and clinical studies. It has been postulated that metabolism via hydrogenation of the 8,9-double bonds of these molecules would unmask the electrophilic, and thus, the toxic nature of their cyclopropyl moieties. Illudins S and M were found to be rapidly metabolized by NADPH-dependent alkenal/one oxidoreductase (AOR) with maximal rates of 115.9 and 44.1 micromol x min(-1) mg(-1), and K(m)s of 308 and 109 microM, respectively. Irofulven was reduced at a much slower rate: V(max) 275 nmol min(-1) mg(-1) and K(m) 145 microM. Human 293 cells transfected with an AOR overexpression vector were 100-fold more sensitive than control cells to irofulven, but displayed little differential sensitivity to illudin M. Addition of glutathione to the alpha,beta-unsaturated ketone moiety of illudin M, but not irofulven, occurred readily at physiological concentrations. Electrophilic intermediates of irofulven and illudin M that were activated by AOR were trapped with glutathione and identified by high performance liquid chromatography with tandem mass spectrometry. Samples of the 60 human tumor cell line panel used by the National Cancer Institute to evaluate potential chemotherapeutic compounds were assayed for AOR activity, which correlated positively with previously determined growth inhibitory measures for irofulven, but not illudin M or S. Collectively, these data indicate that bioactivation of irofulven by AOR plays a predominant role in its chemotherapeutic activity.
伊鲁丁S和M是真菌密环菌产生的极具细胞毒性的产物。它们曾被评估作为潜在的抗癌化疗药物，但显示出不理想的治疗指数。伊洛福芬（6-羟甲基酰基富烯）是伊鲁丁S毒性较小的合成衍生物，在许多临床前和临床研究中已证明非常有效。据推测，这些分子通过8,9-双键氢化进行代谢会暴露出其亲电性质，进而揭示其环丙基部分的毒性。研究发现，伊鲁丁S和M可被NADPH依赖性烯醛/酮氧化还原酶（AOR）快速代谢，最大代谢速率分别为115.9和44.1微摩尔·分钟⁻¹·毫克⁻¹，米氏常数分别为308和109微摩尔。伊洛福芬的还原速率要慢得多：最大反应速率为275纳摩尔·分钟⁻¹·毫克⁻¹，米氏常数为145微摩尔。转染了AOR过表达载体的人293细胞对伊洛福芬的敏感性比对照细胞高100倍，但对伊鲁丁M的敏感性差异不大。在生理浓度下，谷胱甘肽很容易与伊鲁丁M的α,β-不饱和酮部分结合，但不与伊洛福芬结合。由AOR激活的伊洛福芬和伊鲁丁M的亲电中间体被谷胱甘肽捕获，并通过液相色谱-串联质谱法进行鉴定。美国国立癌症研究所用于评估潜在化疗化合物的60种人类肿瘤细胞系样本被检测了AOR活性，该活性与之前测定的伊洛福芬的生长抑制指标呈正相关，但与伊鲁丁M或S无关。总体而言，这些数据表明AOR对伊洛福芬的生物活化在其化疗活性中起主要作用。
