title: Effect of X-ray irradiation on expression of organic anion transporting polypeptides.
abstract: OBJECTIVE
  Some members of the organic anion transporting polypeptide (OATP) family may play critical roles in determining the concentration of anticancer drugs in targeted organs/cells. The purpose of the present study was to investigate whether radiation can alter the expression of OATP in cancer cells so that OATP can be used as a specific drug target for anti-tumor treatment in combination with radiotherapy.
  
  
  METHODS
  Two cancer cell lines (HepG2 and MCF7) were irradiated with three doses of X-ray and the expression levels of six OATP were assessed.
  
  
  RESULTS
  Expressions of several OATP were altered after irradiation. OATP1A2, an OATP that was found to transport anti-tumor drugs and was undetectable in untreated cells, showed dramatically elevated level of expression after irradiation in MCF7 cells. The combined treatment of X-rays and the OATP1A2 substrate methotrexate exerted a more significant effect on growth rate and cell death compared with radiation or methotrexate treatment alone. At certain time points, X-rays increased OATP1A2 level while suppressing the expression of efflux transporters.
  
  
  CONCLUSIONS
  Radiation may simultaneously increase the expression of uptake transporters and decrease the level of efflux transporters, suggesting OATP may be considered a novel target for delivery of anti-neoplastic agents in combination with radiotherapy.
authors.affiliation: College of Life Science, South China Agricultural University , Guangzhou, Guangdong Province.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhan
authors.forename: Juan
authors.initials: J
authors.lastname: Yao
authors.forename: Jiujiu
authors.initials: J
authors.lastname: Huang
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhou
authors.forename: Wenjian
authors.initials: W
authors.lastname: Li
authors.forename: Lixin
authors.initials: L
authors.lastname: Chen
authors.forename: Mei
authors.initials: M
authors.lastname: Hong
mesh_terms: D056945:Hep G2 Cells; D006801:Humans; D061986:MCF-7 Cells; D027361:Organic Anion Transporters / Q000235:genetics*; D059467:Transcriptome / Q000528:radiation effects*; D014965:X-Rays
chemical_list: D027361:Organic Anion Transporters