title: β-Lactam analogues of combretastatin A-4 prevent metabolic inactivation by glucuronidation in chemoresistant HT-29 colon cancer cells.
abstract: Glucuronidation by uridine 5-diphosphoglucuronosyl transferase enzymes (UGTs) is a cause of intrinsic drug resistance in cancer cells. Glucuronidation of combretastatin A-4 (CA-4) was previously identified as a mechanism of resistance in hepatocellular cancer cells. Herein, we propose chemical manipulation of β-lactam bridged analogues of Combretastatin A-4 as a novel means of overcoming drug resistance associated with glucuronidation due to the expression of UGTs in the CA-4 resistant human colon cancer HT-29 cells. The alkene bridge of CA-4 is replaced with a β-lactam ring to circumvent potential isomerisation while the potential sites of glucuronate conjugation are deleted in the novel 3-substituted-1,4-diaryl-2-azetidinone analogues of CA-4. We hypothesise that glucuronidation of CA-4 is the mechanism of drug resistance in HT-29 cells. Ring B thioether containing 2-azetidinone analogues of CA-4 such as 4-(4-(methylthio)phenyl)-3-phenyl-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (27) and 3-hydroxy-4-(4-(methylthio)phenyl)-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (45) were identified as the most potent inhibitors of tumour cell growth, independent of UGT status, displaying antiproliferative activity in the low nanomolar range. These compounds also disrupted the microtubular structure in MCF-7 and HT-29 cells, and caused G2/M arrest and apoptosis. Taken together, these findings highlight the potential of chemical manipulation as a means of overcoming glucuronidation attributed drug resistance in CA-4 resistant human colon cancer HT-29 cells, allowing the development of therapeutically superior analogues.
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland. Electronic address: melibaa@tcd.ie.
authors.forename: Azizah M
authors.initials: AM
authors.lastname: Malebari
authors.affiliation: School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Greene
authors.affiliation: School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Seema M
authors.initials: SM
authors.lastname: Nathwani
authors.affiliation: Molecular Design Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland.
authors.forename: Darren
authors.initials: D
authors.lastname: Fayne
authors.affiliation: School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Niamh M
authors.initials: NM
authors.lastname: O'Boyle
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.affiliation: School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Brendan
authors.initials: B
authors.lastname: Twamley
authors.affiliation: School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Zisterer
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Trinity Biomedical Sciences Institute, 152-160 Pearse Street, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Meegan
mesh_terms: D000972:Antineoplastic Agents, Phytogenic; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000473:pathology; D019008:Drug Resistance, Neoplasm; D005965:Glucuronates / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D008658:Inactivation, Metabolic; D013267:Stilbenes / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship; D047090:beta-Lactams / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005965:Glucuronates; D013267:Stilbenes; D047090:beta-Lactams; C058728:fosbretabulin
keywords: 2-azetidinone; Combretastatin A-4; HT-29 colon cancer cells; Tubulin polymerisation inhibitor; β-lactam