title: Id-1 modulates senescence and TGF-beta1 sensitivity in prostate epithelial cells.
abstract: BACKGROUND
  Loss of sensitivity to TGF-beta1 (transforming growth factor beta1)-induced growth arrest is an important step towards malignant transformation in human epithelial cells, and Id-1 (inhibitor of differentiation or DNA binding-1) has been associated with cell proliferation and cell-cycle progression. Here, we investigated the role of Id-1 in cellular sensitivity to TGF-beta1.
  
  
  RESULTS
  Using an immortalized prostate epithelial cell line, NPTX cells, we suppressed Id-1 expression through antisense strategy. We found that inhibition of Id-1 expression suppressed cell proliferation and at the same time induced cellular senescence and G2/M cell-cycle arrest. In addition, inactivation of Id-1 made cells more vulnerable to TGF-beta1-induced growth arrest. The sensitization effect on TGF-beta1 was associated with up-regulation of two downstream effectors of the TGF-beta1 pathway, p21WAF1/Cip1 and p27KIP1.
  
  
  CONCLUSIONS
  Our results indicate that endogenous Id-1 levels might be a crucial factor in the development of resistance to TGF-beta1-induced growth suppression in human prostate epithelial cells.
authors: Cancer Biology Group, Department of Anatomy, Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.
authors: Kaijun
authors: K
authors: Di
authors: Ming-Tat
authors: MT
authors: Ling
authors: Sai Wah
authors: SW
authors: Tsao
authors: Yong Chuan
authors: YC
authors: Wong
authors: Xianghong
authors: X
authors: Wang