title: Spica prunellae and its marker compound rosmarinic acid induced the expression of efflux transporters through activation of Nrf2-mediated signaling pathway in HepG2 cells.
abstract: BACKGROUND
  Spica prunellae (SP) is a well-known traditional Chinese medicinal herb with properties of antihypertensive, antihyperglycemic, antiviral, anti-inflammatory, and antitumor activities. This herb is also popularly consumed as a food additive in some drinks or other food forms for treating pyreticosis. Rosmarinic acid (RA) is the marker compound from SP, which possesses anti-oxidative and anti-inflammatory functions.
  
  
  OBJECTIVE
  This study aims to investigate the regulatory effect of the water extract of SP (WESP) and RA on efflux transports (ETs), including P-glycoprotein (p-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) in HepG2 cell line. Results would provide beneficial information for the proper application of SP in clinics.
  
  
  METHODS
  HepG2 cells were treated with different doses of the tested drugs for 24 or 96h. MTT assay was used to examine cell viability. The protein and mRNA levels of the ETs were measured by using Western blot and real-time PCR, respectively. Reporter assay was used to study the antioxidant response element (ARE)-luciferin activity by using HepG2-C8 cells, which were generated by transfecting plasmid containing ARE-luciferin gene into HepG2 cells. The transport activities of ETs were tested by using substrate probes.
  
  
  RESULTS
  WESP significantly (p<0.05) increased the expression of ETs in a dose-dependent manner. The increase caused by WESP was stronger than RA alone. Both WESP and RA promoted the translocation of nuclear factor E2-related factor-2 (Nrf2) from cytoplasm to the nucleus as well as significantly (p<0.05) enhanced the ARE-luciferin activity. WESP and RA also enhanced the efflux activity of P-gp and MRP2, accompanied by marked increase (p<0.05) in the intracellular ATP levels.
  
  
  CONCLUSIONS
  WESP could significantly induce the expression of ETs through the activation of Nrf2-mediated signaling pathway in HepG2 cells. RA could be one of the active compounds responsible for the induction. WESP and RA also enhanced the efflux activity of P-gp and MRP2, and the increased intracellular ATP levels were likely involved in this induction. Results of this study provide a better understanding of the regulation of SP on ETs and the underlying molecular mechanism. Results indicated that potential drug-drug interactions may exist when SP is co-administered with other substrate drugs that are transported via the ETs, especially P-gp and MRP2, thereby providing beneficial information for appropriate use of SP for clinical therapy.
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Jinjun
authors.initials: J
authors.lastname: Wu
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Yuanfeng
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Fangyuan
authors.initials: F
authors.lastname: Li
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Guiyu
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Shi
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Rilan
authors.initials: R
authors.lastname: Ou
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Yunli
authors.initials: Y
authors.lastname: Tong
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau (SAR), China.
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China; State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau (SAR), China. Electronic address: lllu@gzucm.edu.cn.
authors.forename: Linlin
authors.initials: L
authors.lastname: Lu
authors.affiliation: Interational Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China; State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau (SAR), China. Electronic address: liuzq@gzucm.edu.cn.
authors.forename: Zhongqiu
authors.initials: Z
authors.lastname: Liu
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D002934:Cinnamates / Q000378:metabolism*; D053630:Depsides / Q000378:metabolism*; D004365:Drugs, Chinese Herbal; D056945:Hep G2 Cells; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism*; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction; D000097123:Rosmarinic Acid
chemical_list: D015415:Biomarkers; D002934:Cinnamates; D053630:Depsides; D004365:Drugs, Chinese Herbal; D026901:Membrane Transport Proteins; D012097:Repressor Proteins; D000097123:Rosmarinic Acid; C111027:NKRF protein, human
keywords: Efflux transports; Nuclear factor E2-related factor-2; Rosmarinic acid; Spica prunellae