title: miR-192/miR-215 influence 5-fluorouracil resistance through cell cycle-mediated mechanisms complementary to its post-transcriptional thymidilate synthase regulation.
abstract: Thymidylate synthase (TYMS) is a target of the most widely used chemotherapeutic agents against gastrointestinal malignancies, the fluoropyrimidine-based therapy. TYMS expression levels have been identified as predictive biomarkers for 5-fluoruracil (FU) response in colorectal cancer, but their clinical utility remains controversial. The complexity of fluoropyrimidine response must require more mechanisms that currently have not been completely elucidated. In this context, microRNAs (miRNA) may play a role in modulating chemosensitivity. By carrying out an in silico analysis coupled to experimental validation, we detected that miR-192 and miR-215 target TYMS expression in colorectal cancer cell lines. However, downregulation of TYMS by these miRNAs does not sensitize colorectal cancer cell lines to FU treatment. The overexpression of miR-192/215 significantly reduces cell proliferation by targeting cell cycle progression. This effect was partially associated with p53 status, because reduction of cell proliferation and cell cycle arrest was associated with p21 and p27 induction. The decrease of S-phase cells by these miRNAs mitigates the effects of S phase-specific drugs and suggests that other mechanisms different from TYMS overexpression are essential to direct FU resistance. Finally, ectopic expression of miR-192/215 might have stronger impact to predict FU response than TYMS inhibition. Prospective studies to elucidate the role of these miRNAs as predictive biomarkers to FU are necessary.
authors.affiliation: Oncology Unit, Casa Sollievo Sofferenza, S. Giovanni Rotondo, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Boni
authors.forename: Nerea
authors.initials: N
authors.lastname: Bitarte
authors.forename: Ion
authors.initials: I
authors.lastname: Cristobal
authors.forename: Ruth
authors.initials: R
authors.lastname: Zarate
authors.forename: Javier
authors.initials: J
authors.lastname: Rodriguez
authors.forename: Evaristo
authors.initials: E
authors.lastname: Maiello
authors.forename: Jesus
authors.initials: J
authors.lastname: Garcia-Foncillas
authors.forename: Eva
authors.initials: E
authors.lastname: Bandres
mesh_terms: D001665:Binding Sites; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects* / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D019295:Computational Biology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005472:Fluorouracil / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000235:genetics; D013940:Thymidylate Synthase / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: C546783:MIRN192 microRNA, human; C553667:MIRN215 microRNA, human; D035683:MicroRNAs; D013940:Thymidylate Synthase; D005472:Fluorouracil