Document Detail


Knockdown of inwardly rectifying potassium channel Kir2.2 suppresses tumorigenesis by inducing reactive oxygen species-mediated cellular senescence.
MedLine Citation:
PMID:  20841375     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Senescence is an important determinant of treatment outcome in cancer therapy. In the present study, we show that knockdown of the inwardly rectifying K(+) channel Kir2.2 induced growth arrest without additional cellular stress in cancer cells lacking functional p53, p16, and/or Rb. Kir2.2 knockdown also induced senescence-associated β-galactosidase activity and upregulated senescence marker proteins in multiple cancer cell lines derived from different tissues, including prostate, stomach, and breast. Interestingly, knockdown of Kir2.2 induced a significant increase in reactive oxygen species (ROS) that was accompanied by cell cycle arrest, characterized by significant upregulation of p27, with concomitant downregulation of cyclinA, cdc2, and E2F1. Kir2.2 knockdown cells displayed increased levels of PML bodies, DNA damage (γH2AX) foci, senescence-associated heterochromatin foci, mitochondrial dysfunction, secretory phenotype, and phosphatase inactivation. Conversely, overexpression of Kir2.2 decreased doxorubicin-induced ROS accumulation and cell growth inhibition. Kir2.2 knockdown-induced cellular senescence was blocked by N-acetylcysteine, indicating that ROS is a critical mediator of this pathway. In vivo tumorigenesis analyses revealed that tumors derived from Kir2.2 knockdown cells were significantly smaller than those derived from control cells (P < 0.0001) and showed a remarkable increase in senescence-associated proteins, including senescence-associated β-galactosidase, p27, and plasminogen activator inhibitor-1. Moreover, the preestablished tumors are reduced in size after the injection of siKir2.2 (P = 0.0095). Therefore, we propose for the first time that Kir2.2 knockdown induces senescence of cancer cells by a mechanism involving ROS accumulation that requires p27, but not Rb, p53, or p16.
Authors:
Inkyoung Lee; Chaehwa Park; Won Ki Kang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-14
Journal Detail:
Title:  Molecular cancer therapeutics     Volume:  9     ISSN:  1538-8514     ISO Abbreviation:  Mol. Cancer Ther.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101132535     Medline TA:  Mol Cancer Ther     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2951-9     Citation Subset:  IM    
Copyright Information:
©2010 AACR.
Affiliation:
Biomedical Research Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-Dong, Seoul, Korea.
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