Waxman D J, Sundseth S S, Srivastava P K, Lapenson D P
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Cancer Res. 1992 Oct 15;52(20):5797-802.
Glutathione S-transferases (GSTs) play an important role in the detoxification of diverse electrophilic chemicals, including anticancer drugs. Gene-specific oligonucleotide probes were developed to monitor the expression of individual GST mRNAs in livers of adult male rats treated with drugs and other chemical modulators of GST expression. Northern blot analysis of total liver RNA using probes specific for individual GSTs belonging to classes alpha (GSTs Ya1, Ya2, Yc), mu (GSTs Yb1, Yb2, Yb3), pi (GST Yp), and GSTms demonstrated the expression in liver of all but Yp mRNA. Kidney GST expression was at least as high as that in liver for GSTs Ya1, Yc, and Yp, while it was substantially lower but still detectable for GSTs Ya2, Yb2, and GSTms. Several of the liver GST class alpha mRNAs, in particular Ya2, were inducible by pretreatment of rats with phenobarbital or isosafrole. In contrast, dexamethasone preferentially induced Yb1, Yb2, and Ya2, while two other inducers of liver drug metabolism, isoniazid and clofibrate, were less effective with respect to GST induction. GSTms mRNA was induced to a small extent or not at all by the agents tested. Treatment of adult male rats with the anticancer drug cisplatin increased liver expression of GST Yc mRNA and suppressed Ya1 mRNA levels with little or no major effect on several other GST mRNAs. Western blot analysis of liver cytosols prepared from the cisplatin-treated rats revealed corresponding changes in GST Yc and Ya protein levels. Comparable changes in liver GST Ya1 and Yc expression were effected by the cisplatin analogue iproplatin but not by carboplatin or transplatin. This pattern of response to these platinum drugs is comparable to that seen with respect to platinum drug-induced gonadal toxicity and modulation of liver cytochrome P450 expression, suggesting a common mechanistic basis for these diverse effects of platinum anticancer drugs on hepatic enzymes of drug metabolism. Together, these studies demonstrate the utility of oligonucleotide probes for phenotyping liver tissue for the expression of GST enzymes that can contribute to anticancer drug metabolism and resistance. They also raise the possibility of drug-drug interactions involving cisplatin and alkylating agent anticancer drugs that can be metabolized in liver by alpha-class GSTs.
谷胱甘肽S-转移酶（GSTs）在多种亲电化学物质（包括抗癌药物）的解毒过程中发挥着重要作用。已开发出基因特异性寡核苷酸探针，用于监测用药物和其他GST表达化学调节剂处理的成年雄性大鼠肝脏中各个GST mRNA的表达。使用针对属于α类（GSTs Ya1、Ya2、Yc）、μ类（GSTs Yb1、Yb2、Yb3）、π类（GST Yp）和GSTms的单个GST的特异性探针，对肝脏总RNA进行Northern印迹分析，结果表明除Yp mRNA外，所有其他mRNA在肝脏中均有表达。对于GSTs Ya1、Yc和Yp，肾脏中的GST表达至少与肝脏中的一样高，而对于GSTs Ya2、Yb2和GSTms，其表达则明显较低，但仍可检测到。通过用苯巴比妥或异黄樟素预处理大鼠，可诱导肝脏中几种α类GST mRNA，特别是Ya2。相反，地塞米松优先诱导Yb1、Yb2和Ya2，而肝脏药物代谢的另外两种诱导剂异烟肼和氯贝丁酯在GST诱导方面效果较差。所测试的试剂对GSTms mRNA的诱导作用很小或根本没有诱导作用。用抗癌药物顺铂处理成年雄性大鼠，可增加肝脏中GST Yc mRNA的表达，并抑制Ya1 mRNA水平，对其他几种GST mRNA几乎没有或没有重大影响。对顺铂处理的大鼠制备的肝脏胞质溶胶进行蛋白质免疫印迹分析，结果显示GST Yc和Ya蛋白水平有相应变化。顺铂类似物异丙铂可引起肝脏中GST Ya1和Yc表达的类似变化，但卡铂或反铂则无此作用。这种对这些铂类药物的反应模式与铂类药物诱导的性腺毒性和肝脏细胞色素P450表达的调节情况相似，表明铂类抗癌药物对肝脏药物代谢酶的这些不同作用有共同的机制基础。总之，这些研究证明了寡核苷酸探针在对肝脏组织进行表型分析以检测可能参与抗癌药物代谢和耐药性的GST酶表达方面的实用性。它们还提出了涉及顺铂和可在肝脏中由α类GSTs代谢的烷基化剂抗癌药物之间药物相互作用的可能性。
