title: Intrinsic properties of tumour cells have a key impact on the bystander effect mediated by genetically engineered mesenchymal stromal cells.
abstract: BACKGROUND
  Engineered mesenchymal stromal cells (MSC) have been used in many preclinical studies of gene directed enzyme/prodrug therapy. We aimed to compare the efficacy of two most frequently used systems, as well as evaluate the extent of a bystander effect mediated by therapeutic MSC towards cell lines derived from different tumours.
  
  
  METHODS
  Two approaches were compared: (i) herpes simplex virus thymidine kinase (TK)/ganciclovir (GCV) and (ii) yeast cytosine deaminase fused with uracil phosphoribosyltransferase (CD::UPRT)/5-fluorocytosine (5-FC). The cytotoxic effect mediated by therapeutic MSC was evaluated in direct co-culture by a fluorimetric assay. The expression profile of tumour cells was analyzed by a quantitative polymerase chain reaction, and the ability of gap-junctional intercellular communication (GJIC) was evaluated by a dye transfer assay.
  
  
  RESULTS
  Both systems were effective only on glioblastoma cells (8-MG-BA). The CD::UPRT-MSC/5-FC system showed efficiency on melanoma A375 cells. We decreased the sensitivity of 8-MG-BA cells and A375 cells to the CD::UPRT-MSC/5-FC system by pharmacological inhibition of thymidylate synthase, and we achieved a similar result in A375 cells by inhibition of thymidine phosphorylase. Although we demonstrated functional GJIC in A375 cells, TK-MSC were ineffective in mediating the bystander effect similarly to HeLa cells, which were also relatively resistant to CD::UPRT-MSC/5-FC treatment. TK-MSC/GCV treatment had a strong cytotoxic effect on MDA-MB-231 cells (breast carcinoma), whereas CD::UPRT-MSC/5-FC treatment failed as a result of overexpression of the gene for ABCC11. Transfection of the MDA-MB-231 cell line with small interference RNA specific to ABCC11 led to a significantly increased sensitivity to the CD::UPRT-MSC/5-FC approach.
  
  
  CONCLUSIONS
  GJIC, expression of enzymes involved in drug metabolism and ABC transporters correlate with the response of tumour cells to treatment by MSC-expressing prodrug-converting genes.
authors.affiliation: Laboratory of Molecular Oncology, Cancer Research Institute of Slovak Academy of Sciences, Bratislava, Slovakia. exonmigu@savba.sk
authors.forename: Miroslava
authors.initials: M
authors.lastname: Matuskova
authors.forename: Lenka
authors.initials: L
authors.lastname: Baranovicova
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Kozovska
authors.forename: Erika
authors.initials: E
authors.lastname: Durinikova
authors.forename: Andrea
authors.initials: A
authors.lastname: Pastorakova
authors.forename: Lubica
authors.initials: L
authors.lastname: Hunakova
authors.forename: Iveta
authors.initials: I
authors.lastname: Waczulikova
authors.forename: Radim
authors.initials: R
authors.lastname: Nencka
authors.forename: Lucia
authors.initials: L
authors.lastname: Kucerova
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D024201:Bystander Effect; D002450:Cell Communication; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005437:Flucytosine / Q000378:metabolism / Q000494:pharmacology; D015774:Ganciclovir / Q000378:metabolism / Q000494:pharmacology; D017629:Gap Junctions / Q000378:metabolism; D015870:Gene Expression; D020868:Gene Silencing; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D010430:Pentosyltransferases / Q000235:genetics* / Q000378:metabolism; D011355:Prodrugs / Q000378:metabolism / Q000494:pharmacology; D012190:Retroviridae / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D018528:ATP-Binding Cassette Transporters; D011355:Prodrugs; D005437:Flucytosine; D010430:Pentosyltransferases; C023269:uracil phosphoribosyltransferase; D013937:Thymidine Kinase; D043525:Cytosine Deaminase; D015774:Ganciclovir