title: Mesalazine negatively regulates CDC25A protein expression and promotes accumulation of colon cancer cells in S phase.
abstract: Regular consumption of mesalazine has been associated with a reduced risk of colorectal cancer (CRC) in patients with inflammatory bowel disease. The molecular mechanisms underlying the antineoplastic effect of 5-aminosalicylic acid remain, however, poorly characterized. In this study, we examined whether mesalazine affects cell cycle progression and analyzed specific checkpoint pathways in experimental models of CRC. Mesalazine inhibited the growth of HCT-116 and HT-29 cells, two CRC cell lines that express either a wild-type or mutated p53. Cell cycle analysis revealed that mesalazine induced cells to accumulate in S phase. This effect was associated with a sustained phosphorylation of the cyclin-dependent kinase (CDK)2 at threonine 14 and tyrosine 15 residues, an event that inactivates the CDK2-cyclin complex and blocks S-G(2) phase cell cycle transition. Consistently, mesalazine reduced the protein content of CDC25A, a phosphatase that regulates CDK2 phosphorylation status. Analysis of upstream kinases that negatively control CDC25A expression showed that mesalazine enhanced the activation of CHK1 and CHK2. However, silencing of CHK1 and CHK2 did not prevent the mesalazine-induced CDC25A protein downregulation. In contrast, CDC25A protein ubiquitination and degradation and accumulation of cells in S phase following mesalazine exposure were reverted by proteasome inhibitors. Notably, mesalazine also inhibited CDC25A in human CRC explants. Finally, we showed that mesalazine downregulated CDC25A in CT26, a murine CRC cell line, and prevented the formation of CT26-derived tumors in mice. Data show that mesalazine negatively regulates CDC25A protein expression, thus delaying CRC cell progression.
authors.affiliation: Dipartimento di Medicina Interna, Università Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
authors.forename: Carmine
authors.initials: C
authors.lastname: Stolfi
authors.forename: Daniele
authors.initials: D
authors.lastname: Fina
authors.forename: Roberta
authors.initials: R
authors.lastname: Caruso
authors.forename: Flavio
authors.initials: F
authors.lastname: Caprioli
authors.forename: Massimo Claudio
authors.initials: MC
authors.lastname: Fantini
authors.forename: Angelamaria
authors.initials: A
authors.lastname: Rizzo
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Sarra
authors.forename: Francesco
authors.initials: F
authors.lastname: Pallone
authors.forename: Giovanni
authors.initials: G
authors.lastname: Monteleone
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D047468:Immunoprecipitation; D019804:Mesalamine / Q000494:pharmacology*; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016196:S Phase / Q000187:drug effects*; D020687:cdc25 Phosphatases / Q000096:biosynthesis / Q000187:drug effects*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D019804:Mesalamine; C517005:Cdc25a protein, mouse; D020687:cdc25 Phosphatases