title: The multidrug resistance 1 (MDR1) gene polymorphism G-rs3789243-A is not associated with disease susceptibility in Norwegian patients with colorectal adenoma and colorectal cancer; a case control study.
abstract: BACKGROUND
  Smoking, dietary factors, and alcohol consumption are known life style factors contributing to gastrointestinal carcinogenesis. Genetic variations in carcinogen handling may affect cancer risk. The multidrug resistance 1(MDR1/ABCB1) gene encodes the transport protein P-glycoprotein (a phase III xenobiotic transporter). P-glycoprotein is present in the intestinal mucosal lining and restricts absorption of certain carcinogens, among these polycyclic aromatic hydrocarbons. Moreover, P-glycoprotein transports various endogenous substrates such as cytokines and chemokines involved in inflammation, and may thereby affect the risk of malignity. Hence, genetic variations that modify the function of P-glycoprotein may be associated with the risk of colorectal cancer (CRC). We have previously found an association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of CRC in a Danish study population. The aim of this study was to investigate if this MDR1 polymorphism was associated with risk of colorectal adenoma (CA) and CRC in the Norwegian population.
  
  
  METHODS
  Using a case-control design, the association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of colorectal carcinomas and adenomas in the Norwegian population was assessed in 167 carcinomas, 990 adenomas, and 400 controls. Genotypes were determined by allelic discrimination. Odds ratio (OR) and 95 confidence interval (95% CI) were estimated by binary logistic regression.
  
  
  RESULTS
  No association was found between the MDR1 polymorphism (G-rs3789243-A) and colorectal adenomas or cancer. Carriers of the variant allele of MDR1 intron 3 had odds ratios (95% CI) of 0.97 (0.72-1.29) for developing adenomas, and 0.70 (0.41-1.21) for colorectal cancer, respectively, compared to homozygous wild type carriers.
  
  
  CONCLUSIONS
  The MDR1 intron 3 (G-rs3789243-A) polymorphism was not associated with a risk of colorectal adenomas or carcinomas in the present Norwegian study group. Thus, this MDR1 polymorphism does not seem to play an important role in colorectal carcinogenesis in this population.
authors.affiliation: Medical Department, Viborg Regional Hospital, 8800 Viborg, Denmark. va9791@gmail.com
authors.forename: Vibeke
authors.initials: V
authors.lastname: Andersen
authors.forename: Lene
authors.initials: L
authors.lastname: Agerstjerne
authors.forename: Dorte
authors.initials: D
authors.lastname: Jensen
authors.forename: Mette
authors.initials: M
authors.lastname: Østergaard
authors.forename: Mona
authors.initials: M
authors.lastname: Saebø
authors.forename: Julian
authors.initials: J
authors.lastname: Hamfjord
authors.forename: Elin
authors.initials: E
authors.lastname: Kure
authors.forename: Ulla
authors.initials: U
authors.lastname: Vogel
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000236:Adenoma / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000235:genetics*; D016001:Confidence Intervals; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007438:Introns; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009664:Norway; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1