title: Reversal effects of Rabdosia rubescens extract on multidrug resistance of MCF-7/Adr cells in vitro.
abstract: BACKGROUND
  Rabdosia rubescens (Hemsl.) Hara (Lamiaceae) is widely used in traditional Chinese medicines for the treatment of antitumor, antimicrobial, anti-inflammatory and antioxidation. It is also used as a supplement in the treatment of many cancers, such as esophagus, mammary gland, liver and prostate cancers.
  
  
  OBJECTIVE
  To investigate the multidrug resistance (MDR) reversal effects and its possible mechanism of R. rubescens extracts on human breast cancer cell line MCF-7/Adr (Michigan Cancer Foundation--7/adriamycin resistance).
  
  
  METHODS
  Rabdosia rubescens were extracted by reflux extraction method with different solvent such as petroleum ether, chloroform, ethyl acetate, n-butyl alcohol and water in order and obtain petroleum ether fraction (PEF), chloroform fraction (CF), ethyl acetate fraction (EAF), n-butyl alcohol fraction (BAF) and aqueous fraction (AF). The active extract fractions of R. rubescens were screened by rhodamine123 (Rh123) accumulation assay. Cytotoxicity of the effect fraction was examined by the MTT assay; the intracellular accumulation of adriamycin and expression of P-gp were examined by flow cytometry; the gene transcription of MDR1 was determined by RT-PCR.
  
  
  RESULTS
  CF and EAF fractions could increase the intracellular accumulation of adriamycin in MCF-7/Adr cells, PEF, BAF and AF fractions showed little effect on the intracellular accumulation of adriamycin or Rh123. When adriamycin was used in combination with CF and EAF fractions at non-toxic concentration on MCF-7/Adr cells, CF and EAF fractions can reverse MDR of MCF-7/Adr cells, and the reverse folds were 2.16 (CF, 4 μg/mL), 4.60 (CF, 20 μg/mL), 1.87 (EAF, 4 μg/mL) and 4.02 (EAF, 20 μg/mL), respectively. After treatment with CF (4.20 μg/mL) and EAF (4.20 μg/mL) for 48 h, the MDR1 gene expression level in MCF-7/Adr cells was decreased by 40.17, 48.14, 33.86 and 42.52%, and the abundance of P-gp also decreased by 8.63, 24.53, 27.50 and 34.91% in MCF-7/Adr cells, respectively.
  
  
  CONCLUSIONS
  These results indicate the therapeutic value of chloroform fraction (CF) and ethyl acetate fraction (EAF) from R. rubescens as potential MDR reversing agents and warranted further investigation.
authors.affiliation: National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.
authors.forename: Farong
authors.initials: F
authors.lastname: Li
authors.forename: Jufang
authors.initials: J
authors.lastname: Fan
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wu
authors.forename: Rui Yuan
authors.initials: RY
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Guo
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Dong
authors.forename: Zhezhi
authors.initials: Z
authors.lastname: Wang
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000378:metabolism / Q000627:therapeutic use; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D018938:Caco-2 Cells; D004317:Doxorubicin / Q000378:metabolism / Q000627:therapeutic use; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D037602:Isodon / Q000737:chemistry*; D061986:MCF-7 Cells; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D035261:Plant Components, Aerial / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D004365:Drugs, Chinese Herbal; D009363:Neoplasm Proteins; D010936:Plant Extracts; D012997:Solvents; D004317:Doxorubicin