7,3',4'-Trihydroxyisoflavone modulates multidrug resistance transporters and induces apoptosis via production of reactive oxygen species.
The development of multidrug resistance (MDR) to conventional chemoradiation therapy usually leads to failure in treating cervical cancer. This study aims to explore the effects and mechanisms of 7,3',4'-trihydroxyisoflavone (7,3',4'-THIF), one of the major metabolites of daidzein, on potentiating cytotoxicity of epirubicin (Epi), an anticancer drug in human cervical cancer HeLa cells. The cytotoxicity of Epi remarkably increased when it was combined with 7,3',4'-THIF. The cotreatment increased the reactive oxygen species (ROS) levels, including hydrogen peroxide and superoxide free radicals. 7,3',4'-THIF was shown to down-regulate the MDR1 promoter region composed of the elements of AP1, GC-box, and Y-box, as demonstrated by a luciferase assay. A negative regulation of hMDR1 gene with multiple transcription factors by this isoflavone may provide a novel molecular mechanism for MDR modulation. The mRNA expressions of MDR1, MDR-associated protein (MRP) 1, and MRP2 for the combined treatment were significantly lower than those of the Epi treatment. This result implies that MDR transporter-mediated Epi resistance is inhibited at various degrees by the addition of 7,3',4'-THIF. This isoflavone significantly enhanced intracellular Epi accumulation in HeLa cells. 7,3',4'-THIF and/or Epi triggered apoptosis through the upregulation of p53, Bax, and caspase-9. Apoptosis induction was also confirmed by the reduced mitochondrial membrane potential, increased sub-G1 and G2/M phases, nuclear DNA fragmentation, and chromatin condensation. Our findings demonstrate for the first time that 7,3',4'-THIF causes cell death in human cervical cancer cells through the ROS-dependent suppression of MDR transporters and p53-mediated activation of the intrinsic mitochondrial pathway of apoptosis. Thus, 7,3',4'-THIF has the potential to enhance the activity of a broad range of cancer chemotherapeutics in the MDR spectrum with the advantage of reducing adverse effects.
Department of Biological Sciences and Technology, National University of Tainan, Tainan, Taiwan. yulilo@mail.nutn.edu.tw
Yu-Li
YL
Lo
Wanjen
W
Wang
Cheng-Ta
CT
Ho
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D053453:Caspase 9 / Q000235:genetics / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D015251:Epirubicin / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D000970:Antineoplastic Agents; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D015251:Epirubicin; D007529:Isoflavones; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C000715087:ABCC2 protein, human; C494826:BAX protein, human; C495901:TP53 protein, human; C004742:daidzein; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C061213:3',4',7-trihydroxyisoflavone; C421109:multidrug resistance-associated protein 1