title: Quercetin reduces cyclin D1 activity and induces G1 phase arrest in HepG2 cells.
abstract: Quercetin is able to inhibit proliferation of malignant tumor cells; however, the exact mechanism involved in this biological process remains unclear. The current study utilized a quantitative proteomic analysis to explore the antitumor mechanisms of quercetin. The leucine of HepG2 cells treated with quercetin was labeled as d3 by stable isotope labeling by amino acids in cell culture (SILAC). The isotope peaks of control HepG2 cells were compared with the d3-labeled HepG2 cells by mass spectrometry (MS) to identify significantly altered proteins. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses were subsequently employed to verify the results of the MS analysis. A flow cytometry assay was designed to observe the influence of various quercetin treatment concentrations on the cell cycle distribution of HepG2 cells. The results indicated that quercetin is able to substantially inhibit proliferation of HepG2 cells and induce an obvious morphological alteration of cells. According to the MS results, the 70 credibly-changed proteins that were identified may play important roles in multiple cellular processes, including protein synthesis, signaling, cytoskeletal processes and metabolism. Among these functional proteins, the expression of cyclin D1 (CCND1) was found to be significantly decreased. RT-PCR and western blot analyses verified the SILAC-MS results of decreased CCND1 expression. In summary, flow cytometry revealed that quercetin is able to induce G1 phase arrest in HepG2 cells. Based on the aforementioned observations, it is suggested that quercetin exerts antitumor activity in HepG2 cells through multiple pathways, including interfering with CCND1 gene expression to disrupt the cell cycle and proliferation of HepG2 cells. In the future, we aim to explore this effectin vivo.
authors.affiliation: Lung Cancer Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, P.R. China; Department of Chemotherapy, Sichuan Cancer Hospital, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Lung Cancer Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: L U
authors.initials: LU
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital, Chengdu Medical College, Chengdu, Sichuan 610041, P.R. China.
authors.forename: L I
authors.initials: LI
authors.lastname: Fang
authors.affiliation: Department of Chemotherapy, Sichuan Cancer Hospital, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xie
authors.affiliation: Department of Chemotherapy, Sichuan Cancer Hospital, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Wenxiu
authors.initials: W
authors.lastname: Yao
authors.affiliation: Department of Chemotherapy, Sichuan Cancer Hospital, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Chemotherapy, Sichuan Cancer Hospital, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Zhujuan
authors.initials: Z
authors.lastname: Xiong
authors.affiliation: Lung Cancer Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: L I
authors.initials: LI
authors.lastname: Wang
authors.affiliation: Lung Cancer Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Zhixi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Lung Cancer Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Luo
keywords: SILAC-MS; cell cycle; cyclin D1; quantitative proteomics; quercetin