419 ALL-TRANS RETINOIC ACID INDUCED CELL CYCLE ARREST AND APOPTOSIS OF DU145 CELLS THROUGH CDK5 ACTIVATION

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research1 Apr 2011419 ALL-TRANS RETINOIC ACID INDUCED CELL CYCLE ARREST AND APOPTOSIS OF DU145 CELLS THROUGH CDK5 ACTIVATION Eugene Lin, Mei-Chih Chen, Chien-Te Ku, Mao-Sheng Lin, and Ho Lin Eugene LinEugene Lin Chang-hua, Taiwan More articles by this author , Mei-Chih ChenMei-Chih Chen Tai-chung, Taiwan More articles by this author , Chien-Te KuChien-Te Ku Tai-chung, Taiwan More articles by this author , Mao-Sheng LinMao-Sheng Lin Chang-hua, Taiwan More articles by this author , and Ho LinHo Lin Tai-chung, Taiwan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.508AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES All-trans retinoic acid (ATRA), the active metabolite of vitamin A, is proved to play an important role in inducing cell apoptosis. It is a potent inhibitor of cancer cell growth and has been shown to be efficacious in therapy and prevention of various types of cancer. The pathways by which ATRA inhibits the growth of carcinoma cells seem to vary between cell types and still need further investigation. The present study was undertaken to obtain further insights into the mechanisms by which ATRA induces growth inhibition in the human hormone refractory prostate cancer cell line, DU145 and the roles of Cdk5 and p35 in this process. METHODS DU145 cells were cultured with or without ATRA for varying periods of time. Cell number and viability were measured by trypan blue staining and MTT assay. The expression of specific proteins in the signaling pathway, Egr-1, Cdk5 and p35 were detected by immunoblotting. Subcellular localization of Cdk5 and p35 was analyzed by immunofluorescence microscopy. To identify the role of Cdk5 in ATRA-induced DU145 cells apoptosis, cells were treated with roscovitine, a potent and specific inhibitor of Cdk5 kinase and DNA content was measured using flow cytometry. RESULTS Treatment with ATRA effectively inhibited the total living cell counts and the cell viability. Cdk5, p35 and Egr1 expression showed a significant increase in the treated cells. In the control cell, Cdk5 was seen primarily localized in the cytoplasma and p35 in both the nucleus and cytoplasma. After treatment with 1£gM ATRA, both Cdk5 and p35 protein expression were seen increased in the cytoplasm. Co-treatment with ATRA and the specific inhibitor of Cdk5, Roscovitine, retrieved the drop of cell viability which was induced by ATRA. We found that the accumulation of DU145 cells in sub-G1 phase was apparently increased by ATRA treatment whereas cotreatment with roscovitine could reverse this effect. It is believed that the accumulation of cells in sub-G1 phase indicates DNA fragmentation, which is a common index of apoptosis. CONCLUSIONS Our results are the first demonstration of the biological function of Cdk5 kinase/p35 in ATRA related growth inhibition in hormone refractory prostate cancer cells. We hope that the application of this finding would help to increase the efficiency of clinical chemotherapy in hormone refractory prostate cancer in the near future. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e168-e169 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Eugene Lin Chang-hua, Taiwan More articles by this author Mei-Chih Chen Tai-chung, Taiwan More articles by this author Chien-Te Ku Tai-chung, Taiwan More articles by this author Mao-Sheng Lin Chang-hua, Taiwan More articles by this author Ho Lin Tai-chung, Taiwan More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...