title: [Reversal of multidrug resistance property of carcinoma cells by down-regulating transcription of mdr-1].
abstract: OBJECTIVE
  To reverse the multidrug resistance (MDR) property of carcinoma cells by blocking transcription of activating sites of mdr-1.
  
  
  METHODS
  Breast carcinoma cells were transinfected with several antisense oligonucleotide (ASODN) complementary to mdr-1 by lipofectin. RT-PCR was used to detect the production of mdr-1mRNA. The expression of P-glycoprotein (gp) was then detected by immunohistochemistry and the function of P-gp was detected by rhodamine123 retention.
  
  
  RESULTS
  Forty-eight hours after transfection, mdr-1 index of cells treated by ASODN complementary to MA zone (major initiation start zone), MI (minor initiation start zone), C zone (CAAT box), G zone (GC box) of mdr-1 gene was 1.4, 1.9, 1.6 and 2.1 respectively. The rate of P-gp protein expression in treated cells was 14%, 43%, 26% and 39% respectively. The intracellular Rh123 retention in treated cells was 125%, 83%, 102% and 77% respectively. There was significant difference between cells treated by ASODN complementary to MA zone and C zone and drug-resistant cells.
  
  
  CONCLUSIONS
  The ASODN complementary to MA zone and C zone of mdr-1 gene can reverse MDR of drug-resistant cells to various extent, amongst which the former is more effective. Down-regulating transcription of mdr-1 by blocking transcription activating sites can reduce the expression of mdr-1mRNA and P-gp, and thus reversing MDR of carcinoma cells. The ASODN complementary to MI zone, G zone of mdr-1 however do not significantly reverse the MDR property.
authors.affiliation: Department of Pathology, School of Medicine, University of Shandong, Jinan 250012, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Geng-yin
authors.initials: GY
authors.lastname: Zhou
authors.forename: Gang
authors.initials: G
authors.lastname: Yin
authors.forename: Zhi-fu
authors.initials: ZF
authors.lastname: Wang
authors.forename: Wen-jun
authors.initials: WJ
authors.lastname: Liu
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Lin
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D015536:Down-Regulation; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger