title: Inhibition of lung cancer cell growth by quercetin glucuronides via G2/M arrest and induction of apoptosis.
abstract: Lung cancer is the leading cause of cancer death in many developed countries, including Taiwan. Quercetin, a widely distributed bioflavonoid, is well known to induce growth inhibition in a variety of human cancer cells. Quercetin glucuronides are the main circulating metabolites after dietary supplements with quercetin in humans. However, there is little information available as to how quercetin glucuronides affect human cancer cells. We investigated the effects of quercetin glucuronides in a human lung cancer cell line NCI-H209. We checked the cell viability, cell cycle checkpoint proteins, pro- and antiapoptotic proteins, caspase-3 activity, and gene expression by flow cytometry and Western blot. The viability of cells decreased in a dose- and time-dependent manner. Cell cycle analysis revealed a significant increase of the proportion of cells in G2/M phase and subG0/G1 phase (corresponding to apoptotic cells). Moreover, quercetin glucuronides increased the expressions of cyclin B, Cdc25c-ser-216-p, and Wee1 proteins, indicating the G2/M arrest. We also demonstrated a concurrent decrease of the mitochondrial membrane potential, release of cytochrome c, up-regulation of Bax, down-regulation of Bcl-2, and activation of caspase-3, and subsequently, cleavage of poly(ADP-ribose) polymerase. In addition, quercetin glucuronide-induced apoptosis was totally blocked by the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone. Taken together, we demonstrated that quercetin glucuronides inhibited proliferation through G2/M arrest of the cell cycle and induced apoptosis via caspase-3 cascade in the human lung cancer cell line NCI-H209. Delineation of the biological effects of specific major quercetin metabolites on chemotherapeutic potential or chemoprevention of human cancers warrants further investigation.
authors.affiliation: Department of Dermatology, Chung Shan Medical University Hospital, Taichung, Taiwan, Republic of China.
authors.forename: Jen-Hung
authors.initials: JH
authors.lastname: Yang
authors.forename: Te-Chun
authors.initials: TC
authors.lastname: Hsia
authors.forename: Hsiu-Maan
authors.initials: HM
authors.lastname: Kuo
authors.forename: Pei-Dawn Lee
authors.initials: PD
authors.lastname: Chao
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Chou
authors.forename: Yau-Huei
authors.initials: YH
authors.lastname: Wei
authors.forename: Jing-Gung
authors.initials: JG
authors.lastname: Chung
mesh_terms: D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D053938:DNA Fragmentation; D016195:G2 Phase / Q000187:drug effects; D020719:Glucuronides / Q000494:pharmacology*; D006801:Humans; D008175:Lung Neoplasms; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D008938:Mitosis / Q000187:drug effects; D011794:Quercetin / Q000494:pharmacology*; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D020719:Glucuronides; D017382:Reactive Oxygen Species; D011794:Quercetin