Dickkopf 4 positively regulated by the thyroid hormone receptor suppresses cell invasion in human hepatoma cells

• DOI: 10.1002/hep.24740
• Publication Date: 2011-10-12T17:51:48Z
• Authors: Chen-Hsin Liao; Chau-Ting Yeh; Ya-Hui Huang; Sheng-Ming Wu; Hsiang-Cheng Chi; Ming-Ming Tsai; Chung-Ying Tsai; Chia-Jung Liao; Yi-Hsin Tseng; Yang-Hsiang Lin; Cheng-Yi Chen; I-Hsiao Chung; Wan-Li Cheng; Wei-Jan Chen; Kwang-Huei Lin
• Keywords: Adult; Aged, 80 and over; Male; 0301 basic medicine; Carcinoma, Hepatocellular; Receptors, Thyroid Hormone; Liver Neoplasms; Down-Regulation; Mice, Nude; In Vitro Techniques; Middle Aged; 3. Good health; Mice; 03 medical and health sciences; Cell Movement; Cell Line, Tumor; Disease Progression; Animals; Humans; Intercellular Signaling Peptides and Proteins; Female; Aged; Cell Proliferation

Thyroid hormone (T3) mediates cellular growth, development, and differentiation by binding to the nuclear thyroid hormone receptor (TR). Recent studies suggest that long-term hypothyroidism is associated with human hepatocellular carcinoma (HCC) independent from other major HCC risk factors. Dickkopf (DKK) 4, a secreted protein, antagonizes the Wnt signal pathway. In this study, we demonstrate that T3 may play a suppressor role by inducing DKK4 expression in HCC cells at both the messenger RNA (mRNA) and protein levels. DKK4 was down-regulated in 67.5% of HCC cancerous tissues. The decrease in DKK4 levels was accompanied by a concomitant decrease in TR protein levels in the matched cancerous tissues in 31% of tissues compared by immunoblotting with the adjacent noncancerous tissues. Further, TR and DKK4 expression levels were positively correlated in both normal and cancerous specimens by tissue array analysis. In function assays, stable

DKK4

transfected into J7 or HepG2 cells decreased cell invasion

in vitro

. Conversely, knocking down DKK4 restores cell invasiveness. DKK4-expressing J7 clones showed increased degradation of β-catenin, but down-regulation of CD44, cyclin D1, and c-Jun. To investigate the effect of DKK4 and TR on tumor growth

in vivo

, we established a xenograft of J7 cells in nude mice. J7-DKK4 and J7-TRα1 overexpressing mice, which displayed growth arrest, lower lung colony formation index, and smaller tumor size than in control mice, supporting an inhibitory role of DKK4 in tumor progression.

Conclusion :

Taken together, these data suggest that the TR/DKK4/Wnt/β-catenin cascade influences the proliferation and migration of hepatoma cells during the metastasis process and support a tumor suppressor role of the TR.