title: Transcriptional activation of the carboxylesterase 2 gene by the p53 pathway.
abstract: The p53 tumor suppressor is an important regulator of cellular response to chemotherapeutic agents by virtue of the protein's ability, upon activation by phosphorylation, to transcriptionally activate a number of genes involved in cell proliferation, apoptosis, and metabolism. Transcriptome analysis following introduction of a constitutively active form of p53 (p53T18D/S20D) into colon carcinoma cell lines identified transcriptional activation of the carboxylesterase 2 (CES-2) gene, which is involved in drug metabolism. We examined whether p53 activated by the DNA-damaging drug 5-fluorouracil (5-FU) also induces CES-2 expression. Our experiments showed that 5-FU induced CES-2 expression in two colon carcinoma cell lines that express wild-type p53 (HCT116 p53(+/+) and RKO) but not in five lines that are p53-null (HCT116 p53(-/- )) or express mutated p53 (HT29, KM12C, KM12SM, and KM12L4A). Sequence analysis revealed a putative p53-binding element in the first intron of CES-2 that differed from consensus by one nucleotide. A reporter gene assay showed that the luciferase construct with the p53-binding element responded to 5-FU treatment, whereas the reporter construct without the binding element did not. Chromatin immunoprecipitation assay confirmed that p53 bound the CES-2 fragment containing the p53-binding element after 5-FU treatment, whereas p21 binding to p53 was present with or without chemotherapy. Knockdown of expression of CES-2 and p53 by small interference RNA in RKO and HCT116 p53(+/+) cells attenuated the anti-proliferation effects of CPT11. These results taken together show that activated p53 directly regulates CES-2 expression via a p53-binding site, representing a novel mechanism through which the p53 pathway modulates drug metabolism. In addition, the degree of homology in the p53-binding element may determine the strength of p53 regulation.
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Woonyoung
authors.initials: W
authors.lastname: Choi
authors.forename: David
authors.initials: D
authors.lastname: Cogdell
authors.forename: Yumei
authors.initials: Y
authors.lastname: Feng
authors.forename: Stanley R
authors.initials: SR
authors.lastname: Hamilton
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D043182:Carboxylesterase / Q000235:genetics*; D045744:Cell Line, Tumor; D002843:Chromatin / Q000235:genetics; D003110:Colonic Neoplasms / Q000235:genetics*; D016384:Consensus Sequence; D004249:DNA Damage; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000187:drug effects / Q000235:genetics; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D002843:Chromatin; D017931:DNA Primers; D004273:DNA, Neoplasm; D016159:Tumor Suppressor Protein p53; C517204:CES2 protein, human; D043182:Carboxylesterase; D005472:Fluorouracil