title: Fucoxanthin induces cell cycle arrest at G0/G1 phase in human colon carcinoma cells through up-regulation of p21WAF1/Cip1.
abstract: Fucoxanthin, a natural carotenoid, has been reported to have antitumorigenic activity in mouse colon, skin and duodenum models. The present study was designed to evaluate the molecular mechanisms of fucoxanthin against colon cancer using the human colon adenocarcinoma cell lines. Fucoxanthin reduced the viability of WiDr cells in a dose-dependent manner accompanied by the induction of cell cycle arrest during the G0/G1 phase at 25 microM and apoptosis at 50 microM. Fucoxanthin at 25 microM inhibited the phosphorylation of the retinoblastoma protein (pRb) at Ser780 and Ser807/811 24 h after treatment without changes in the protein levels of the D-types of cyclin and cyclin-dependent kinase (cdk) 4, whose complexes are responsible for the phosphorylation of pRb at these sites. A cdk inhibitory protein, p21WAF1/Cip1 increased 24 h after the treatment with 25 microM of fucoxanthin, but not p27Kip1. In addition, the mRNA of p21WAF1/Cip1 also increased in a dose-dependent manner. According to the experiments using the isogenic human colon adenocarcinoma cell lines, fucoxanthin failed to induce G0/G1 arrest in the p21-deficient HCT116 cells, but not in HCT116 wild-type cells. All of these findings showed that fucoxanthin inhibited proliferation of colon cancer cells. The inhibitory mechanism is due to the cell cycle arrest during the G0/G1 phase mediated through the up-regulation of p21WAF1/Cip1, which may be related to the antitumorigenic activity.
authors.affiliation: Department of Life Science, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai, Kobe, Nada, Hyogo 657-8501, Japan.
authors.forename: Swadesh K
authors.initials: SK
authors.lastname: Das
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shimizu
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sowa
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Komoto
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kanazawa
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D016193:G1 Phase / Q000187:drug effects; D045325:HCT116 Cells; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016160:Retinoblastoma Protein / Q000378:metabolism; D015854:Up-Regulation; D024341:Xanthophylls / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016160:Retinoblastoma Protein; D024341:Xanthophylls; C025164:fucoxanthin