The E3 ubiquitin ligase Siah1 is a prosurvival factor overexpressed in oral cancer
Shu-Chen Hsieh1, and Ju-Hwa Lin2
1
Institute of Food Science and Technology, National Taiwan University, Taipei 106, Taiwan
2
Department of Life Sciences, National Cheng Kung University, Tainan 70101, Taiwan
Abstract
Background/Aim. This study aimed at investigating the expression and functional
significance of Siah1, an E3 ubiquitin ligase, in oral squamous cell carcinoma (OSCC).
Materials and Methods. Comparative genomic hybridization and real-time PCR were
performed to examine the amplification of Siah1 gene in clinical specimens of OSCC tissues. Expression of Siah1 mRNA and protein was examined by quantitative RT-PCR and immunohistochemistry assays, respectively. Apoptosis was examined by Annexin V-staining and PARP-cleavage with or without siRNA-mediated Siah1 knockdown.
Results. Levels of Siah1 DNA and mRNA significantly increased in clinical OSCC
specimens and in cultured OSCC cells, which also stained positive for Siah1 protein. Knockdown of Siah1 led to growth suppression and apoptosis induction in a p53-independent mechanism.
Conclusion. These results revealed a tight correlation of Siah1 overexpression with
