Abstract
The aim of this study was to examine whether Nedd4L (neural precursor cell expressed, developmentally down-regulated 4-like) participated in gallbladder carcinogenesis. We first immunohistochemically examined the expression of Nedd4L in various gallbladder tissue specimens. Weak immunoreactivity to Nedd4L-specific antibody was observed in normal or dysplastic epithelial cells. Cancer cells in non-invasive regions exhibited little immunoreactivity, whereas strong immunostaining was found in cytoplasm of many invasive cancers, especially at cancer invasive front with desmoplastic reaction. Notably, siRNA-mediated silencing of the Nedd4L gene significantly decreased the Matrigel-invasion activity and collagen invasion activity of cultured gallbladder cancer cells, without affecting the cell growth. The subtractive mRNA hybridization followed by RT-PCR and immunoblotting revealed that down-regulation of Nedd4L significantly decreased the expression of collagenases, matrix metalloproteinase (MMP)-1 and -13, in gallbladder cancer cells. Finally, immunohistochemical staining showed that many Nedd4L-expressing invasive gallbladder cancer cells co-expressed MMP-1 and MMP-13. These results indicated that over-expression of Nedd4L might lead to gallbladder cancer invasion by regulating the transcription of the MMP-1 and MMP-13 genes.