title: Analysis of the impact of extracellular acidity on the expression and activity of P-glycoprotein and on the P-glycoprotein-mediated cytotoxicity of daunorubicin in cancer cell by microfluidic chip technology.
abstract: OBJECTIVE
  To explore the impact of extracellular acidic environment on the expression and activity of P-glycoprotein (P-gp) and on the P-gp-mediated cytotoxicity of daunomycin in cancer cells by using microfluidic chip technology.
  
  
  METHODS
  The A549 cells cultured on a microfluidic chip were divided into experiment group and control group. The experiment group was exposed to an acidic cell culture medium (pH 6.6), while the control group was treated with a neutral cell culture medium (pH 7.4). The expression of P-gp was detected by cell immunofluorescense analysis and the activity of P-gp was evaluated by Rhodamine 123 efflux experiment. Meanwhile, the cytotoxicity of daunomycin was analyzed by cell live/dead fluorescence staining method.
  
  
  RESULTS
  Microfluidic chip designed in this study could provide a suitable microenvironment for the growth of A549 cells and the A549 cells reached the confluence of 90% after inoculation for 72 h. Treatment of the acidic cell culture media on A549 cells did not make a significant difference on the expression level of P-gp. However, the activity of P-gp was significantly enhancement and peaked at 6 h after treatment with acidic cell culture media. Meanwhile, the cytotoxicity of daunomycin reduced significantly after treatment with acidic cell culture medium for 6 h,and a reversal effect was obtained when synergy with verapamil.
  
  
  CONCLUSIONS
  Microfluidic chip technology can shorten the analysis time and reduce the reagent consumption. It can be used as a new technology platform for understanding the mechanisms of multi-drug resistance and for screening highly efficient multi-drug resistance reversal agents.
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Yuan
authors: Y
authors: Li
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Jiao
authors: J
authors: Xiang
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Sha-sha
authors: SS
authors: Zhang
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Bei-zhong
authors: BZ
authors: Liu
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Fang
authors: F
authors: Gong
authors: Central Laboratory, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China.
authors: Ming-qing
authors: MQ
authors: Peng
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D003470:Culture Media; D003630:Daunorubicin; D005110:Extracellular Space; D006801:Humans; D006863:Hydrogen-Ion Concentration; D044085:Microfluidics
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D003470:Culture Media; D003630:Daunorubicin