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Transient enhancement of proliferation of neural progenitors and impairment of their long-term survival in p25 transgenic mice. Oncotarget 2018; 7:39148-39161. [PMID: 27283769 PMCID: PMC5129921 DOI: 10.18632/oncotarget.9834] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/29/2016] [Indexed: 12/26/2022] Open
Abstract
Cyclin-dependent kinase 5 (CDK5) regulates important neuronal functions via p35. p35 undergoes cleavage in response to neuronal activity and neurotoxic conditions to release its subunit p25. Although p25 has been implicated in various neurodegenerative diseases, the mechanisms by which p25 mediates neurodegenerative impairment have not been fully elucidated. We aimed to determine the role of p25-mediated neurodegeneration on neurogenesis in an inducible transgenic mouse line overexpressing p25 (p25 TG) in the forebrain. Adult neuronal progenitor cells (NPCs) were labeled with BrdU in vivo, which were significantly increased in numbers in the subventricular zone, the hippocampus, and the cortex of p25 TG mice. Consistently, more mitotic cells were observed in p25 TG mice than in controls, even in the cortex and the CA1, which are not neurogenic regions. BrdU-positive cells were negative for GFAP or γ-H2AX, suggesting that they are not astrocytes or dying cells. Neurospheres derived from the dentate gyrus and the cortex were significantly increased in p25 TG mice and can be differentiated into astrocytes and neurons. However, p25 TG decreased the long-term survival of proliferating NPCs and severely impaired adult neurogenesis. A Transwell co-culture system was used to assess the influence of p25-expressing primary neurons on adult NPCs. Co-culture with p25-expressing neurons downregulated Ki67 expression and upregulated cleaved caspase-3, indicating that the paracrine signaling in cell-cell communication is essential for NPC survival and proliferation. Moreover, increased CDK5 activity impairs Wnt activation. This study demonstrates that hyperactivation of p25 may temporarily enhance NPC proliferation, but impair their long-term survival.
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Zhang S, Lu Z, Mao W, Ahmed AA, Yang H, Zhou J, Jennings N, Rodriguez-Aguayo C, Lopez-Berestein G, Miranda R, Qiao W, Baladandayuthapani V, Li Z, Sood AK, Liu J, Le XF, Bast RC. CDK5 Regulates Paclitaxel Sensitivity in Ovarian Cancer Cells by Modulating AKT Activation, p21Cip1- and p27Kip1-Mediated G1 Cell Cycle Arrest and Apoptosis. PLoS One 2015; 10:e0131833. [PMID: 26146988 PMCID: PMC4492679 DOI: 10.1371/journal.pone.0131833] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 06/06/2015] [Indexed: 01/12/2023] Open
Abstract
Cyclin-dependent kinase 5 (CDK5) is a cytoplasmic serine/ threonine kinase. Knockdown of CDK5 enhances paclitaxel sensitivity in human ovarian cancer cells. This study explores the mechanisms by which CDK5 regulates paclitaxel sensitivity in human ovarian cancers. Multiple ovarian cancer cell lines and xenografts were treated with CDK5 small interfering RNA (siRNA) with or without paclitaxel to examine the effect on cancer cell viability, cell cycle arrest and tumor growth. CDK5 protein was measured by immunohistochemical staining of an ovarian cancer tissue microarray to correlate CDK5 expression with overall patient survival. Knockdown of CDK5 with siRNAs inhibits activation of AKT which significantly correlates with decreased cell growth and enhanced paclitaxel sensitivity in ovarian cancer cell lines. In addition, CDK5 knockdown alone and in combination with paclitaxel induced G1 cell cycle arrest and caspase 3 dependent apoptotic cell death associated with post-translational upregulation and nuclear translocation of TP53 and p27Kip1 as well as TP53-dependent transcriptional induction of p21Cip1 in wild type TP53 cancer cells. Treatment of HEYA8 and A2780 wild type TP53 xenografts in nu/nu mice with CDK5 siRNA and paclitaxel produced significantly greater growth inhibition than either treatment alone. Increased expression of CDK5 in human ovarian cancers correlates inversely with overall survival. CDK5 modulates paclitaxel sensitivity by regulating AKT activation, the cell cycle and caspase-dependent apoptosis. CDK5 inhibition can potentiate paclitaxel activity in human ovarian cancer cells.
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Affiliation(s)
- Shu Zhang
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- Department of General Surgery, the Second Affiliated Hospital, School of Medicine, Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Zhen Lu
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Weiqun Mao
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Ahmed A. Ahmed
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Hailing Yang
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Jinhua Zhou
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Nicholas Jennings
- Departments of Gynecologic Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Cristian Rodriguez-Aguayo
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Gabriel Lopez-Berestein
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Roberto Miranda
- Departments of Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, Untied States of America
| | - Wei Qiao
- Bioinformatics Computer Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Veera Baladandayuthapani
- Bioinformatics Computer Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Zongfang Li
- Department of General Surgery, the Second Affiliated Hospital, School of Medicine, Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Anil K. Sood
- Departments of Gynecologic Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Jinsong Liu
- Departments of Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, Untied States of America
| | - Xiao-Feng Le
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail: (RCB); (XFL)
| | - Robert C. Bast
- Departments of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail: (RCB); (XFL)
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