Carcinogenesis Advance Access published online on August 8, 2007
Carcinogenesis, doi:10.1093/carcin/bgm185
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Role of p14ARF in TWIST-mediated senescence in prostate epithelial cells

* Department of Anatomy, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, SAR, China
Department of Pathology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, SAR, China
Corresponding Authors: Dr Xianghong Wang and Prof Y. C. Wong, Dept of Anatomy, Laboratory Block, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, SAR, China. Fax: 852 2817 0857, Tel. 852 2819 2867, Email: xhwang{at}hkucc.hku.hk and ycwong{at}hkuc.hku.hk
Recently, TWIST, a basic helix-loop-helix transcription factor, is suggested to be an oncogene because of its overexpression in many types of human cancer and its positive role in promoting cell survival. The aim of this study was to investigate the role of TWIST on the growth of human epithelial cells. Using two immortalized human prostate epithelial cell lines, we demonstrated that inactivation of TWIST by small RNA technology led to promotion of cellular senescence and growth arrest, suggesting that TWIST plays a key role in the continuous proliferation of immortalized cells. Overexpression of TWIST, in contrast, resulted in suppression of cellular senescence in response to genotoxic damage and promotion of cell proliferation with DNA damage accumulation, indicating that TWIST promotes genomic instability. In addition, we also found that the TWIST-mediated cellular senescence was regulated through its negative effect on p14ARF and subsequent suppression of MDM2/p53 and Chk1/2 DNA damage response pathways. Our results suggest that overexpression of TWIST results in downregulation of p14ARF which leads to the impairment of DNA damage checkpoint in response to genotoxic stress. This negative effect of TWIST on DNA damage response facilitates uncontrolled cell proliferation with genomic instability and tumorigenesis in non-malignant cells.
Key Words: TWIST p14ARF senescence epithelial cells
Received June 6, 2007; revised August 2, 2007; accepted August 2, 2007.