ABSTRACT
Pharmacokinetic drug resistance is a serious obstacle that emerges during cancer chemotherapy. In this study, we investigated the possible role of aldo-keto reductase 1C3 (AKR1C3) in the resistance of cancer cells to anthracyclines. First, the reducing activity of AKR1C3 toward anthracyclines was tested using incubations with a purified recombinant enzyme. Furthermore, the intracellular reduction of daunorubicin and idarubicin was examined by employing the transfection of A549, HeLa, MCF7 and HCT 116 cancer cells with an AKR1C3 encoding vector. To investigate the participation of AKR1C3 in anthracycline resistance, we conducted MTT cytotoxicity assays with these cells, and observed that AKR1C3 significantly contributes to the resistance of cancer cells to daunorubicin and idarubicin, whereas this resistance was reversible by the simultaneous administration of 2'-hydroxyflavanone, a specific AKR1C3 inhibitor. In the final part of our work, we tracked the changes in AKR1C3 expression after anthracycline exposure. Interestingly, a reciprocal correlation between the extent of induction and endogenous levels of AKR1C3 was recorded in particular cell lines. Therefore, we suggest that the induction of AKR1C3 following exposure to daunorubicin and idarubicin, which seems to be dependent on endogenous AKR1C3 expression, eventually might potentiate an intrinsic resistance given by the normal expression of AKR1C3. In conclusion, our data suggest a substantial impact of AKR1C3 on the metabolism of daunorubicin and idarubicin, which affects their pharmacokinetic and pharmacodynamic behavior. In addition, we demonstrate that the reduction of daunorubicin and idarubicin, which is catalyzed by AKR1C3, contributes to the resistance of cancer cells to anthracycline treatment.
Subject(s)
3-Hydroxysteroid Dehydrogenases/metabolism , Anthracyclines/pharmacology , Antibiotics, Antineoplastic/pharmacology , Carcinoma/drug therapy , Drug Resistance, Neoplasm , Hydroxyprostaglandin Dehydrogenases/metabolism , Neoplasm Proteins/metabolism , 3-Hydroxysteroid Dehydrogenases/antagonists & inhibitors , 3-Hydroxysteroid Dehydrogenases/genetics , Aldo-Keto Reductase Family 1 Member C3 , Anthracyclines/agonists , Anthracyclines/metabolism , Antibiotics, Antineoplastic/agonists , Antibiotics, Antineoplastic/metabolism , Biotransformation , Cell Line, Tumor , Cell Survival/drug effects , Daunorubicin/agonists , Daunorubicin/metabolism , Daunorubicin/pharmacology , Doxorubicin/metabolism , Doxorubicin/pharmacology , Drug Resistance, Neoplasm/drug effects , Drug Synergism , Enzyme Induction/drug effects , Enzyme Inhibitors/pharmacology , Flavanones/pharmacology , Humans , Hydroxyprostaglandin Dehydrogenases/antagonists & inhibitors , Hydroxyprostaglandin Dehydrogenases/genetics , Idarubicin/agonists , Idarubicin/metabolism , Idarubicin/pharmacology , Kinetics , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Oxidation-Reduction , Recombinant Proteins/chemistry , Recombinant Proteins/metabolismABSTRACT
Acute myeloid leukemia (AML) remains a challenging disease to treat and urgently requires new therapies to improve its treatment outcome. In this study, we investigated the molecular mechanisms underlying the cooperative antileukemic activities of panobinostat and cytarabine or daunorubicin (DNR) in AML cell lines and diagnostic blast samples in vitro and in vivo. Panobinostat suppressed expression of BRCA1, CHK1, and RAD51 in AML cells in a dose-dependent manner. Further, panobinostat significantly increased cytarabine- or DNR-induced DNA double-strand breaks and apoptosis, and abrogated S and/or G2/M cell cycle checkpoints. Analogous results were obtained by shRNA knockdown of BRCA1, CHK1, or RAD51. Cotreatment of NOD-SCID-IL2Rγ(null) mice bearing AML xenografts with panobinostat and cytarabine significantly increased survival compared to either cytarabine or panobinostat treatment alone. Additional studies revealed that panobinostat suppressed the expression of BRCA1, CHK1, and RAD51 through downregulation of E2F1 transcription factor. Our results establish a novel mechanism underlying the cooperative antileukemic activities of these drug combinations in which panobinostat suppresses expression of BRCA1, CHK1, and RAD51 to enhance cytarabine and daunorubicin sensitivities in AML cells.
