title: Curcumin induces apoptosis in HCT-116 human colon cancer cells in a p21-independent manner.
abstract: Several micronutrients present in fruits and vegetables exhibit anticancer activity as a result of their actions on molecular targets involved in carcinogenesis and tumor progression. Curcumin, a phenolic phytochemical derived from the rhizome of Curcuma longa, exhibits both cancer-preventative activity and growth inhibitory effects on neoplastic cells. Several studies report that curcumin inhibits cancer cell proliferation and induces apoptosis in cancer cells through p21-mediated cell cycle arrest. Cancer cells that are deficient in p21 are also reported to be more prone to undergo apoptosis in response to a variety of cytotoxic agents. In this study, we determined whether curcumin-induced cytotoxicity in cultures of HCT-116 human colon cancer cells was dependent on p21 status. Curcumin killed wild-type HCT-116 cells in a dose- and time-dependent manner, as measured in an MTT cell viability assay. Moreover, an equivalent cytotoxic effect by curcumin was observed in both p21(+/+) and p21(-/-)HCT-116 cells, indicating that curcumin-induced cytotoxicity was p21-independent. Primary cultures of human dermal fibroblasts were less sensitive than HCT-116 colon cancer cells to lower doses of curcumin, suggesting a degree of selectivity for neoplastic cells. Western blot analysis showed that cell death in curcumin-treated cultures of p21(+/+) and p21(-/-) HCT-116 cells was associated with a reduction in pro-caspase-3 and PARP-1 cleavage, which are indicative of apoptosis. We conclude that curcumin-induced apoptosis in HCT-116 colon cancer cells does not depend on p21 status.
authors.affiliation: Department of Surgery, Faculty of Medicine, 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: 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; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000502:physiology*; D045325:HCT116 Cells; D006801:Humans
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D050759:Cyclin-Dependent Kinase Inhibitor p21; D003474:Curcumin