title: ABCB1-overexpressing MG63/DOX cell xenograft model: maintain the MDR phenotype in vivo.
abstract: BACKGROUND
  Multi-drug resistance (MDR) constitutes a major obstacle in the effectiveness of chemotherapy. P-Glycoprotein (P-gp), the product of ABCB1 gene, is a transmembrane transporter that actively pumps cytotoxic drugs out of tumor cells resulting in MDR.
  
  
  OBJECTIVE
  We sought to establish an MG63/DOX cell xenografts model that maintained the MDR phenotype and molecular properties in vivo in order to screen for new P-gp inhibitors.
  
  
  METHODS
  The cytotoxicities of doxorubicin, paclitaxel and cytarabine were evaluated by MTT assays. P-gp activity was measured by rhodamine 123 accumulation using flow cytometry. P-gp expression in MG63/DOX cells and tumor tissues was detected by western blotting and immunohistochemistry.
  
  
  RESULTS
  Our results showed that MG63/DOX cells exhibited 70-fold resistance to doxorubicin and more than 150-fold resistance to paclitaxel compared with parent MG63 cells. Furthermore, the ABCB1 inhibitor verapamil (10 μM) effectively reversed doxorubicin and paclitaxel resistance by 90- and 200-fold, respectively. The intracellular accumulation of rhodamine 123 was significantly increased (8.35-fold) in MG63/DOX cell, as compared to MG63 cells, in the presence of 10 μM verapamil. MG63/DOX tumor chunk xenografts had a high formation rate (88%). Finally, we found that the ABCB1 gene was overexpressed in different generations of solid tumors.
  
  
  CONCLUSIONS
  These data demonstrated that MG63/DOX tumor chunk subculture in vivo retained their molecular properties. This model could serve as a convenient system for the preclinical investigation of drug combinations and the screening of new agents to reverse ABCB1-mediated MDR.
authors.affiliation: Department of Pharmacy, Affiliated Sixth People’s Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhou
authors.forename: Lili
authors.initials: L
authors.lastname: Wan
authors.forename: Yonglong
authors.initials: Y
authors.lastname: Han
authors.forename: Xiangle
authors.initials: X
authors.lastname: Meng
authors.forename: Quanjun
authors.initials: Q
authors.lastname: Yang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Yu
authors.forename: Zan
authors.initials: Z
authors.lastname: Shen
authors.forename: Cheng
authors.initials: C
authors.lastname: Guo
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D003561:Cytarabine / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology; D017239:Paclitaxel / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D003561:Cytarabine; D004317:Doxorubicin; D014700:Verapamil; D017239:Paclitaxel