Miltirone Is a Dual Inhibitor of P-Glycoprotein and Cell Growth in Doxorubicin-Resistant HepG2 Cells.
Miltirone (1), an abietane-type diterpene quinone isolated from Salvia miltiorrhiza, possesses anticancer activity in p-glycoprotein (P-gp)-overexpressing human cancer cells. Results of the current study suggest a dual effect of miltirone on P-gp inhibition and apoptotic induction in a human hepatoma HepG2 cell line and its P-gp-overexpressing doxorubicin-resistant counterpart (R-HepG2). Miltirone (1) elicited a concentration-dependent cytotoxicity, with a similar potency (EC50 ≈ 7-12 μM), in HepG2 and R-HepG2 cells. Miltirone (1) (1.56-6.25 μM) produced synergistic effects on doxorubicin (DOX)-induced growth inhibition of R-HepG2 (synergism: 0.3 < combination index < 0.5). Molecular docking studies illustrated that miltirone (1) interacted with the active site of P-gp with a higher binding affinity than DOX, suggesting that it was a P-gp inhibitor. Flow cytometric analysis confirmed miltirone (1) as a competitive inhibitor of P-gp. At non-necrotic concentrations (1.56-25 μM), miltirone (1) activated caspase-dependent apoptotic pathways and triggered the generation of reactive oxygen species (ROS) and ROS-mediated mitogen-activated protein kinase (MAPK) signaling pathways (e.g., p38 MAPK, stress-activated protein kinase/c-Jun N-terminal kinase, and extracellular regulated kinase 1/2) in both HepG2 and R-HepG2 cells. Thus, we conclude that miltirone (1) is a dual inhibitor of P-gp and cell growth in human drug-resistant hepatoma cells.
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
Xuelin
X
Zhou
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
Yan
Y
Wang
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
Wayne Y W
WY
Lee
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
Penelope M Y
PM
Or
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
David C C
DC
Wan
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
Yiu Wa
YW
Kwan
School of Biomedical Sciences, ⊥Department of Orthopaedics & Traumatology, Faculty of Medicine, ‡Institute of Chinese Medicine, and §State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong , Hong Kong, People's Republic of China.
John H K
JH
Yeung
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000187:drug effects* / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D020169:Caspases / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008113:Liver Neoplasms; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D015394:Molecular Structure; D010616:Phenanthrenes / Q000494:pharmacology*; D027561:Salvia miltiorrhiza / Q000737:chemistry*
D018435:ATP Binding Cassette Transporter, Subfamily B; D010616:Phenanthrenes; C068880:miltirone; D004317:Doxorubicin; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases