title: Curcumin causes superoxide anion production and p53-independent apoptosis in human colon cancer cells.
abstract: Curcumin from the rhizome of theCurcuma longa plant has chemopreventative activity and inhibits the growth of neoplastic cells. Since p53 has been suggested to be important for anticancer activity by curcumin, we investigated curcumin-induced cytotoxicity in cultures of p53(+/+) and p53(-/-) HCT-116 colon cancer cells, as well as mutant p53 HT-29 colon cancer cells. Curcumin killed wild-type p53 HCT-116 cells and mutant p53 HT-29 cells in a dose- and time-dependent manner. In addition, curcumin-treated p53(+/+) HCT-116 cells and mutant p53 HT-29 cells showed upregulation of total and activated p53, as well as increased expression of p53-regulated p21, PUMA (p53 upregulated modulator of apoptosis), and Bax; however, an equivalent cytotoxic effect by curcumin was observed in p53(+/+) and p53(-/-) HCT-116 cells, demonstrating that curcumin-induced cytotoxicity was independent of p53 status. Similar results were obtained when the cytotoxic effect of curcumin was assessed in wild-type p53 HCT-116 cells after siRNA-mediated p53 knockdown. Chromatin condensation, poly (ADP-ribose) polymerase-1 cleavage and reduced pro-caspase-3 levels in curcumin-treated p53(+/+) and p53(-/-) HCT-116 cells suggested that curcumin caused apoptosis. In addition, exposure to curcumin resulted in superoxide anion production and phosphorylation of oxidative stress proteins in p53(+/+) and p53(-/-) HCT-116 cells. Collectively, our results indicate that, despite p53 upregulation and activation, curcumin-induced apoptosis in colon cancer cells was independent of p53 status and involved oxidative stress. Curcumin may therefore have therapeutic potential in the management of colon cancer, especially in tumorsthatare resistant to conventional chemotherapydue todefects inp53 expression or function.
authors.affiliation: Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Watson
authors.forename: Richard
authors.initials: R
authors.lastname: Hill
authors.forename: Paul B
authors.initials: PB
authors.lastname: Yaffe
authors.forename: Anna
authors.initials: A
authors.lastname: Greenshields
authors.forename: Mark
authors.initials: M
authors.lastname: Walsh
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Lee
authors.forename: Carman A
authors.initials: CA
authors.lastname: Giacomantonio
authors.forename: David W
authors.initials: DW
authors.lastname: Hoskin
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D003474:Curcumin / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D034622:RNA Interference; D013481:Superoxides / Q000378:metabolism*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; C494826:BAX protein, human; C438378:BBC3 protein, human; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D011518:Proto-Oncogene Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D013481:Superoxides; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D003474:Curcumin