title: Modulation of thymidilate synthase and p53 expression by HDAC inhibitor vorinostat resulted in synergistic antitumor effect in combination with 5FU or raltitrexed.
abstract: Despite the introduction of several novel anticancer agents almost 50% of colorectal cancer (CRC) patients die for cancer suggesting the necessity of new therapeutical approaches. In this study we demonstrated that the HDAC inhibitor vorinostat exerted potent antiproliferative effect in a panel of mut- and wt-p53 human CRC cell lines. Moreover, in combination with 5-fluorouracil modulated by folinic acid (5FU-FA) or with Raltitrexed (RTX), both commonly used in the treatment of this disease, it showed a clear schedule-dependent synergistic antiproliferative interaction as demonstrated by calculating combination indexes. Only simultaneous, or 24 h pretreatment with vorinostat followed by either agent, produced synergistic effect paralleled by evident cell cycle perturbations with major S-phase arrest. Moreover, we provided for the first time evidences that vorinostat can overcome resistance to both 5FU and RTX. Downmodulation of Thymidilate synthase (TS) protein induced by vorinostat within 24 h, represented a key factor in enhancing the effects of both drugs in sensitive as well as resistant tumor cells. Furthermore, p53, whose wild-type expression is critical for sensitivity to 5FU and RTX, was upregulated by vorinostat in wt- and downregulated in mut-p53 cells, suggesting an additional mechanism of the antiproliferative synergistic interactions observed. Overall these data add new insights in the mechanism of vorinostat antitumor effect and suggested that the association of vorinostat plus 5FU-FA and/or RTX should be clinically explored.
authors.affiliation: Experimental Pharmacology Unit, Department of Research, Istituto Nazionale Tumori, Via M. Semmola, Naples, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Di Gennaro
authors.forename: Francesca
authors.initials: F
authors.lastname: Bruzzese
authors.forename: Stefano
authors.initials: S
authors.lastname: Pepe
authors.forename: Alessandra
authors.initials: A
authors.lastname: Leone
authors.forename: Paolo
authors.initials: P
authors.lastname: Delrio
authors.forename: Pochi R
authors.initials: PR
authors.lastname: Subbarayan
authors.forename: Antonio
authors.initials: A
authors.lastname: Avallone
authors.forename: Alfredo
authors.initials: A
authors.lastname: Budillon
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005472:Fluorouracil / Q000008:administration & dosage / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D019073:HT29 Cells; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D002955:Leucovorin / Q000008:administration & dosage; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology; D013876:Thiophenes / Q000008:administration & dosage / Q000494:pharmacology; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D000077337:Vorinostat
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D011799:Quinazolines; C495901:TP53 protein, human; D013876:Thiophenes; D016159:Tumor Suppressor Protein p53; D000077337:Vorinostat; D013940:Thymidylate Synthase; C068874:raltitrexed; D002955:Leucovorin; D005472:Fluorouracil