title: Sulforaphane down-regulates SKP2 to stabilize p27(KIP1) for inducing antiproliferation in human colon adenocarcinoma cells.
abstract: Sulforaphane is a cruciferous vegetable-derived isothiocyanate with promising chemopreventive and therapeutic activities. Induction of proliferation arrest and apoptosis principally contribute to sulforaphane's anticancer activity, but the precise molecular mechanisms remain elusive. The oncoprotein SKP2 is a key component of the SKP1-CULLIN1-F-box (SCF) E3 ligase complex and is responsible for directing SCF-mediated degradation of cyclin-dependent kinase inhibitor p27(KIP1) to promote cell proliferation. We herein provide the first evidence supporting the critical involvement of the SKP2-p27(KIP1) axis in sulforaphane-induced antiproliferation in various human colon adenocarcinoma cell lines. Specifically, sulforaphane markedly suppressed the levels of bromodeoxyuridine (BrdU) incorporation and clonogenicity in all tested cell lines, illustrating the antiproliferative effect of sulforaphane. Of note, sulforaphane-induced antiproliferation was accompanied with down-regulation of SKP2, leading to the stabilization and thus up-regulation of p27(KIP1). Additionally, sulforaphane was found to down-regulate SKP2 mainly through transcriptional repression, as sulforaphane lowered SKP2 mRNA expression and the SKP2 promoter activity. Furthermore, sulforaphane treatment led to the activation of both AKT and ERK, thus ruling out the possibility that sulforaphane down-regulates SKP2 by inhibiting AKT or ERK. Notably, sulforaphane-elicited suppression of BrdU incorporation and clonogenicity were significantly rescued in the context of SKP2 overexpression or p27(KIP1) depletion, therefore highlighting the important role of SKP2 down-regulation and the ensuing stabilization of p27(KIP1) in sulforaphane-induced antiproliferation. Collectively, these data expand our molecular understanding about how sulforaphane elicits proliferation arrest, but also implicate the application of sulforaphane in therapeutic modalities targeting SKP2.
authors: Institute of Biomedical Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Department of Physics, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Aqua Fairy Biotechnology Co., Ltd., 2F, No. 6, Aly.20, Ln.41, Shepi Road, Fengyuan District, Taichung 420477, Taiwan. Electronic address: cm709958@yahoo.com.tw.
authors: Yuan-Kai
authors: YK
authors: Chung
authors: Institute of Biomedical Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Department of Life Science, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Department of Anesthesiology, Kuang Tien General Hospital, Dajia Branch, 321 Jingguo Road Dajia District, Taichung 43761, Taiwan. Electronic address: richardor92@yahoo.com.tw.
authors: Richard
authors: R
authors: Chi-Hung Or
authors: Department of Obstetrics and Gynecology, Taichung Veterans General Hospital, 1650 Taiwan Boulevard Sec. 4, Taichung 40705, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University, School of Medicine, 155 Li-Nong Street Sec. 2, Taipei 11221, Taiwan. Electronic address: chlu@vghtc.gov.tw.
authors: Chien-Hsing
authors: CH
authors: Lu
authors: Institute of Biomedical Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan. Electronic address: sun128928@gmail.com.
authors: Wei-Ting
authors: WT
authors: Ouyang
authors: Institute of Biomedical Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan. Electronic address: mg880613@hotmail.com.
authors: Shu-Yi
authors: SY
authors: Yang
authors: Institute of Biomedical Sciences, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Ph.D. Program in Translational Medicine, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Agricultural Biotechnology Center, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan; Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40227, Taiwan. Electronic address: chia_che@dragon.nchu.edu.tw.
authors: Chia-Che
authors: CC
authors: Chang
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects* / Q000235:genetics; D048049:Extracellular Signal-Regulated MAP Kinases; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D055550:Protein Stability / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism*; D013454:Sulfoxides; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation
chemical_list: D017879:Isothiocyanates; D044786:S-Phase Kinase-Associated Proteins; D013454:Sulfoxides; D050760:Cyclin-Dependent Kinase Inhibitor p27; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; C016766:sulforaphane
keywords: Antiproliferation; Colon adenocarcinoma; SKP2; Sulforaphane; p27(KIP1)