Modulation of trabectedin (ET-743) hepatobiliary disposition by multidrug resistance-associated proteins (Mrps) may prevent hepatotoxicity

Abstract

Trabectedin is a promising anticancer agent, but dose-limiting hepatotoxicity was observed during phase I/II clinical trials. Dexamethasone (DEX) has been shown to significantly reduce trabectedinmediated hepatotoxicity. The current study was designed to assess the capability of sandwichcultured primary rat hepatocytes (SCRH) to predict the hepato-protective effect of DEX against trabectedin-mediated cytotoxicity. The role of multidrug resistance-associated protein 2 (Mrp2; Abcc2) in trabectedin hepatic disposition also was examined. In SCRH from wild-type Wistar rats, cytotoxicity was observed after 24-hr continuous exposure to trabectedin. SCRH pretreated with additional DEX (1 µM) exhibited a 2-3-fold decrease in toxicity at 100 nM and 1000 nM trabectedin. Unexpectedly, toxicity in SCRH from Mrp2-deficient (TR − ) compared to wild-type Wistar rats was markedly reduced. Depletion of glutathione from SCRH using buthionine sulfoximine (BSO) mitigated trabectedin toxicity associated with 100 nM and 1000 nM trabectedin. Western blot analysis demonstrated increased levels of CYP3A1/2 and Mrp2 in SCRH pretreated with DEX; interestingly, Mrp4 expression was increased in SCRH after BSO exposure. Trabectedin biliary recovery in isolated perfused livers from TR − rats was decreased by ~75% compared to wild-type livers. In conclusion, SCRH represent a useful in vitro model to predict the hepatotoxicity of trabectedin observed in vivo. The protection by DEX against trabectedin-mediated cytotoxicity may be attributed, in part, to enhanced Mrp2 biliary excretion and increased metabolism by CYP3A1/2. Decreased trabectedin toxicity in SCRH from TR − rats, and in SCRH pretreated with BSO, may be due to increased basolateral excretion of trabectedin by Mrp3 and/or Mrp4.

ABCC2, ABCC3, and ABCB1, but not CYP3A, Protect against Trabectedin-Mediated Hepatotoxicity

“…It has been shown that pretreatment with dexamethasone reduces the hepatotoxic effects of trabectedin (12,13). Although not completely understood, it was suggested that this protective effect could be due to increased metabolism by CYP3A enzymes (14,15). Although dexamethasone is indeed a well-known inducer of CYP3A, it is also a potent inducer of ABCC2 (30).…”

“…The mechanism of how dexamethasone reduces the hepatotoxicity is not understood, but it has been suggested that its protective effect could be due to increased metabolism by CYP3A enzymes (14,15). Indeed, dexamethasone is a well-known inducer of CYP3A expression (e.g., ref.…”

“…For example, trabectedin was shown to be a substrate for human ABCB1 (P-glycoprotein/MDR1) as well as for mouse Abcb1a in vitro (17). In addition, it was recently shown that there was altered toxicity in hepatocytes from ABCC2 (MRP2)-deficient (TR -) rats, indicating a possible role for ABCC2 in the hepatotoxicity of trabectedin (14). It was also hypothesized that the basolaterally located drug transporter ABCC3 (MRP3) could affect the trabectedin-mediated hepatotoxicity (14).…”

“…In addition, it was recently shown that there was altered toxicity in hepatocytes from ABCC2 (MRP2)-deficient (TR -) rats, indicating a possible role for ABCC2 in the hepatotoxicity of trabectedin (14). It was also hypothesized that the basolaterally located drug transporter ABCC3 (MRP3) could affect the trabectedin-mediated hepatotoxicity (14). Little in vivo evidence, however, is currently available about whether any of these drug transporters affects the disposition, and possibly also the hepatotoxicity, of trabectedin.…”

Trabectedin – the DNA minor groove binder

“…В частности, изменение транспорта трабекте-дина через мембрану клеток печени, которое связано с активацией экспрессии и функций аденозинтрифос-фатзависимого кассетного транспортного белка, ко-дируемого геном Mrp2 (Multidrug Resistance-associated Protein), продемонстрировано на первичной культуре гепатоцитов крысы [50]. Предполагается также, что дексаметазон снижает токсичность трабектедина, бло-кируя воспалительный компонент его действия путем ингибирования NF-κB, который активирует экспрес-сию провоспалительных генов [35,51].…”