title: Silencing MRP1-4 genes by RNA interference enhances sensitivity of human hepatoma cells to chemotherapy.
abstract: OBJECTIVE
  Besides surgical treatment, systematic chemotherapy plays a crucial role in HCC treatment, especially for patients with advanced HCC. However, none of the single-drug-treatment strategies have shown significant survival benefit due to a high incidence rate of chemoresistance. This study was designed to observe the effect of small interfering of RNA (SiRNA) targeting multidrug resistance-related protein 1-4 (MRP1, MRP2, MRP3, and MRP4) in modulating drug resistance of HepG2/ADM and SMMC7721/ADM cells.
  
  
  METHODS
  HepG2/Adriamycin (ADM) and SMMC7721/ADM cell lines were developed by exposing parental cells to stepwise increasing concentrations of ADM. MTT assay was used to determine drug sensitivity and half inhibitory concentration (IC50) of drugs was calculated. Flow cytometry was employed to analyze cell cycle distribution. MRP1-4 mRNA expression levels were measured by quantitative real-time PCR (QRT-PCR). Expression of proteins was analyzed by Western blot. The growth curve was draw and the cell apoptosis was also observed. Animal experiment was used to compare the cell growth.
  
  
  RESULTS
  MTT assay showed that the values of IC50 and RI of HepG2/ADM and SMMC7721/ADM decreased after siRNA treatment in HepG2/ADM cells and SMMC7721/ADM cells. QRT-PCR analysis demonstrated the MRP1-4 mRNA expression decreased significantly in HepG2/ADM cells and SMMC7721/ADM cells after siRNA transfection. In addition, compared with parental cells, MRP1-4 protein expressions apparently decreased in SMMC7721/ADM and HepG2/ADM cells. Flow cytometry showed significantly elevated apoptosis rate following MRP1-4 siRNA transfection. Animal experiment suggested that silencing MRP1-4 gene in vivo inhibited tumor growth.
  
  
  CONCLUSIONS
  Inhibition of MRP1-4 by small interfering RNA enhanced and selectively restored sensitivity of hepatoma cells to drugs. MRP1-4 siRNA might represent a new therapeutic option for HCC.
authors.affiliation: Comprehensive Department, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Guangzhou 510120, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Gastrointestinal Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Guangzhou 510120, China.
authors.forename: Gaojie
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Hepatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Guangzhou 510120, China.
authors.forename: Tingfeng
authors.initials: T
authors.lastname: Fang
authors.affiliation: Department of Gynaecology and Obstetrics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Guangzhou 510120, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Shenzhen Hospital of Armed Police Frontier Corps Shenzhen 518029, China.
authors.forename: Huayao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Shenzhen Hospital of Armed Police Frontier Corps Shenzhen 518029, China.
authors.forename: Shanglin
authors.initials: S
authors.lastname: Yang
authors.affiliation: Shenzhen Hospital of Armed Police Frontier Corps Shenzhen 518029, China.
authors.forename: Jinxing
authors.initials: J
authors.lastname: Wei
authors.affiliation: Department of Gastrointestinal Surgery, Guangdong Provincial People's Hospital Guangzhou 510120, China.
authors.forename: Zejian
authors.initials: Z
authors.lastname: Lv
authors.affiliation: Shenzhen Hospital of Armed Police Frontier Corps Shenzhen 518029, China.
authors.forename: Langping
authors.initials: L
authors.lastname: Tan
authors.affiliation: Department of Hepatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University Guangzhou 510120, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Liu
keywords: Hepatocellular; MRP1-4; multidrug resistance; siRNA