title: Drug transporter gene expression in human colorectal tissue and cell lines: modulation with antiretrovirals for microbicide optimization.
abstract: OBJECTIVE
  The objectives of this study were to comprehensively assess mRNA expression of 84 drug transporters in human colorectal biopsies and six representative cell lines, and to investigate the alteration of drug transporter gene expression after exposure to three candidate microbicidal antiretroviral (ARV) drugs (tenofovir, darunavir and dapivirine) in the colorectal epithelium. The outcome of the objectives informs development of optimal ARV-based microbicidal formulations for prevention of HIV-1 infection.
  
  
  METHODS
  Drug transporter mRNA expression was quantified from colorectal biopsies and cell lines by quantitative real-time PCR. Relative mRNA expression was quantified in Caco-2 cells and colorectal explants after induction with ARVs. Data were analysed using Pearson's product moment correlation (r), hierarchical clustering and principal component analysis (PCA).
  
  
  RESULTS
  Expression of 58 of the 84 transporters was documented in colorectal biopsies, with genes for CNT2, P-glycoprotein (P-gp) and MRP3 showing the highest expression. No difference was noted between individual subjects when analysed by age, gender or anatomical site (rectum or recto-sigmoid) (r = 0.95-0.99). High expression of P-gp and CNT2 proteins was confirmed by immunohistochemical staining. Similarity between colorectal tissue and cell-line drug transporter gene expression was variable (r = 0.64-0.84). PCA showed distinct clustering of human colorectal biopsy samples, with the Caco-2 cells defined as the best surrogate system. Induction of Caco-2 cell lines with ARV drugs suggests that darunavir-based microbicides incorporating tenofovir may result in drug-drug interactions likely to affect distribution of individual drugs to sub-epithelial target cells.
  
  
  CONCLUSIONS
  These findings will help optimize complex formulations of rectal microbicides to realize their full potential as an effective approach for pre-exposure prophylaxis against HIV-1 infection.
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Indrani
authors.initials: I
authors.lastname: Mukhopadhya
authors.affiliation: Department of Pathology, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Graeme I
authors.initials: GI
authors.lastname: Murray
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Berry
authors.affiliation: Department of Gastroenterology, Aberdeen Royal Infirmary, Aberdeen, UK.
authors.forename: John
authors.initials: J
authors.lastname: Thomson
authors.affiliation: Particle Sciences Inc., Bethlehem, PA, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Frank
authors.affiliation: Particle Sciences Inc., Bethlehem, PA, USA.
authors.forename: Garry
authors.initials: G
authors.lastname: Gwozdz
authors.affiliation: Mucosal Infection & Immunity Group, Section of Infectious Diseases, Imperial College, London, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Ekeruche-Makinde
authors.affiliation: Mucosal Infection & Immunity Group, Section of Infectious Diseases, Imperial College, London, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Shattock
authors.affiliation: Mucosal & Salivary Biology, Dental Institute, King's College London, London, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Kelly
authors.affiliation: Laboratory of Molecular Microbiology and Biotechnology, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Iannelli
authors.affiliation: Laboratory of Molecular Microbiology and Biotechnology, Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Pozzi
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Emad M
authors.initials: EM
authors.lastname: El-Omar
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Georgina L
authors.initials: GL
authors.lastname: Hold
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK k.hijazi@abdn.ac.uk.
authors.forename: Karolin
authors.initials: K
authors.lastname: Hijazi
mesh_terms: D000368:Aged; D000890:Anti-Infective Agents / Q000378:metabolism*; D018938:Caco-2 Cells; D000069454:Darunavir / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects*; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D011743:Pyrimidines / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D000068698:Tenofovir / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D026901:Membrane Transport Proteins; D011743:Pyrimidines; D012333:RNA, Messenger; D000068698:Tenofovir; C481671:Dapivirine; D000069454:Darunavir