title: Control of stability of cyclin D1 by quinone reductase 2 in CWR22Rv1 prostate cancer cells.
abstract: Aberrant expression of cyclin D1, frequently observed in human malignant disorders, has been linked to the control of G(1)→S cell cycle phase transition and development and progression in carcinogenesis. Cyclin D1 level changes are partially controlled by GSK-3β-dependent phosphorylation at threonine-286 (Thr286), which targets cyclin D1 for ubiquitination and proteolytic degradation. In our continuing studies on the mechanism of prostate cancer prevention by resveratrol, focusing on the role of its recently discovered target protein, quinone reductase 2 (NQO2), we generated NQO2 knockdown CWR22Rv1 using short hairpin RNA (shRNA)-mediated gene silencing approach. We found that, compared with cells expressing NQO2 (shRNA08), NQO2 knockdown cells (shRNA25) displayed slower proliferation and G(1) phase cell accumulation. Immunoblot analyses revealed a significant decrease in phosphorylation of retinoblastoma Rb and cyclin D1 in shRNA25 compared with shRNA08. Moreover, shRNA25 cells showed a 37% decrease in chymotrypsin-like proteasome activity. An increase in AKT activity was also observed in shRNA25, supported by a ∼1.5-fold elevation in phosphorylation and ∼50% reduction/deactivation of GSK-3α/β at Ser21/9, which were accompanied by a decrease in phosphorylation of cyclin D1 at T286. NQO2 knockdown cells also showed attenuation of resveratrol-induced downregulation of cyclin D1. Our results indicate a hitherto unreported role of NQO2 in the control of AKT/GSK-3β/cyclin D1 and highlight the involvement of NQO2 in degradation of cyclin D1, as part of mechanism of chemoprevention by resveratrol.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Room 133, Valhalla, NY 10595, USA. tze-chen_hsieh@nymc.edu
authors.forename: Tze-chen
authors.initials: TC
authors.lastname: Hsieh
authors.forename: Ching-Jen
authors.initials: CJ
authors.lastname: Yang
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Lin
authors.forename: Yong-Syu
authors.initials: YS
authors.lastname: Lee
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Wu
mesh_terms: D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000096:biosynthesis / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D038362:Glycogen Synthase Kinase 3 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000096:biosynthesis; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis / Q000378:metabolism*; D011808:Quinone Reductases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D000077185:Resveratrol; D016160:Retinoblastoma Protein / Q000378:metabolism; D013267:Stilbenes / Q000378:metabolism / Q000494:pharmacology
chemical_list: D034741:RNA, Small Interfering; D016160:Retinoblastoma Protein; D013267:Stilbenes; D019938:Cyclin D1; C419642:NRH - quinone oxidoreductase2; D011808:Quinone Reductases; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex; D000077185:Resveratrol