Raynaud F I, Odell D E, Kelland L R
Cancer Research Campaign Centre for Cancer Therapeutics, Institute of Cancer Research, Sutton, Surrey, UK.
Br J Cancer. 1996 Aug;74(3):380-6. doi: 10.1038/bjc.1996.369.
JM216 (bis-acetato ammine dichloro cyclohexylamine Pt IV) is an oral platinum complex presently undergoing phase II clinical trials. Previous studies have identified some of its biotransformation products in clinical materials. This study evaluated the nature of JM216 biotransformation products intracellularly in two different human ovarian carcinoma cell lines, one relatively sensitive to platinum agents (CH1: JM216 4 h IC50 of 5.8 microM) and the other relatively resistant (SKOV3: JM216 4 h IC50 of 60.7 microM). Metabolic profiles were also evaluated at different growth status and in cells pretreated with buthionine sulphoximine (BSO), an agent known to decrease intracellular glutathione levels. Results showed that JM216 enters the cells and that the nature and percentage of biotransformation products was dependent upon glutathione levels. Furthermore, results support the view that the previously reported peak A biotransformation product contains a glutathione adduct. In exponentially growing SKOV3 cells which contain higher glutathione levels than CH1, (82.5 vs 37.8 nmol mg-1 protein), peak A represented 89% of total platinum 4 h after JM216 exposure compared with only 24% in CH1. Moreover, 60-70% depletion of glutathione achieved by 24 h pretreatment of cells with BSO resulted in a significant decrease in peak A in both cell lines and increased the cytotoxicity of JM216 in both CH1 and SKOV3 by approximately 2-fold. Following a 4 h exposure of exponentially growing SKOV3 cells to JM216, only peak A (89%) and JM216 (11%) could be detected whereas in CH1 cells, peak A (24%), JM216 (73%) and JM118 [cis-ammine dichloro (cyclohexylamine) platinum II] (3%) were detected. However, in CH1 cells at confluence, where glutathione is lower (8 nmol mg-1 protein) four metabolites (plus JM216 itself) were detected following exposure to 50 microM JM216; peak A, JM118, JM383 (bis-acetato ammine (cyclohexylamine) dihydroxy platinum IV) and an unidentified metabolite (D), also observed in patient's plasma ultrafiltrate. In confluent SKOV3 cells exposed to 50 microM JM216, peak A, JM216 and JM118 were detected. A further unidentified metabolite observed in patients receiving JM216 (metabolite F) was not formed inside these tumour cells. Overall, these data suggest that glutathione conjugation represents a major deactivation pathway for JM216.
JM216（双乙酸氨基二氯环己胺铂IV）是一种正在进行II期临床试验的口服铂类配合物。先前的研究已在临床材料中鉴定出其一些生物转化产物。本研究评估了JM216在两种不同的人卵巢癌细胞系中细胞内生物转化产物的性质，一种对铂类药物相对敏感（CH1：JM216 4小时IC50为5.8微摩尔），另一种相对耐药（SKOV3：JM216 4小时IC50为60.7微摩尔）。还评估了不同生长状态以及用丁硫氨酸亚砜胺（BSO）预处理的细胞中的代谢谱，BSO是一种已知可降低细胞内谷胱甘肽水平的药物。结果表明，JM216进入细胞，生物转化产物的性质和百分比取决于谷胱甘肽水平。此外，结果支持以下观点，即先前报道的A峰生物转化产物含有谷胱甘肽加合物。在指数生长的SKOV3细胞中，其谷胱甘肽水平高于CH1（82.5对37.8纳摩尔/毫克蛋白质），在JM216暴露4小时后，A峰占总铂的89%，而在CH1中仅为24%。此外，用BSO对细胞进行24小时预处理使谷胱甘肽消耗60 - 70%，导致两种细胞系中A峰显著降低，并使JM216在CH1和SKOV3中的细胞毒性增加约2倍。将指数生长的SKOV3细胞暴露于JM216 4小时后，仅能检测到A峰（89%）和JM216（11%），而在CH1细胞中，检测到A峰（24%）、JM216（73%）和JM118 [顺式氨基二氯（环己胺）铂II]（3%）。然而，在汇合的CH1细胞中，其谷胱甘肽水平较低（8纳摩尔/毫克蛋白质），在暴露于50微摩尔JM216后检测到四种代谢产物（加上JM216本身）；A峰、JM118、JM383（双乙酸氨基（环己胺）二羟基铂IV）和一种未鉴定的代谢产物（D），也在患者血浆超滤液中观察到。在暴露于50微摩尔JM216的汇合SKOV3细胞中，检测到A峰、JM216和JM118。在接受JM216的患者中观察到的另一种未鉴定的代谢产物（代谢产物F）在这些肿瘤细胞内未形成。总体而言，这些数据表明谷胱甘肽结合是JM216的主要失活途径。
