1. Hepatocyte-specific Smad7 deletion accelerates DEN-induced HCC via activation of STAT3 signaling in mice
- Author
-
P. ten Dijke, Andreas Teufel, J Dzieran, Silke Marhenke, Stephan Kanzler, Thorsten Maass, Timo Gaiser, Teng Feng, Arndt Vogel, MP Ebert, Felix Rückert, X Yuan, Steven Dooley, NM Meindl-Beinker, A Dropmann, and I Kleiter
- Subjects
0301 basic medicine ,Genetically modified mouse ,Cancer Research ,integumentary system ,Cell cycle ,Biology ,medicine.disease_cause ,Molecular oncology ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,Growth factor receptor ,Apoptosis ,030220 oncology & carcinogenesis ,Hepatocyte ,Cancer research ,medicine ,STAT protein ,Original Article ,Carcinogenesis ,Molecular Biology - Abstract
TGF-β signaling in liver cells has variant roles in the dynamics of liver diseases, including hepatocellular carcinoma (HCC). We previously found a correlation of high levels of the important endogenous negative TGF-β signaling regulator SMAD7 with better clinical outcome in HCC patients. However, the underlying tumor-suppressive molecular mechanisms are still unclear. Here, we show that conditional (TTR-Cre) hepatocyte-specific SMAD7 knockout (KO) mice develop more tumors than wild-type and corresponding SMAD7 transgenic mice 9 months after diethylnitrosamine (DEN) challenge, verifying SMAD7 as a tumor suppressor in HCC. In line with our findings in patients, Smad7 levels in both tumor tissue as well as surrounding tissue show a significant inverse correlation with tumor numbers. SMAD7 KO mice presented with increased pSMAD2/3 levels and decreased apoptosis in the tumor tissue. Higher tumor incidence was accompanied by reduced P21 and upregulated c-MYC expression in the tumors. Activation of signal transducer and activator of transcription factor 3 signaling was found in Smad7-deficient mouse tumors and in patients with low tumoral SMAD7 expression as compared with surrounding tissue. Together, our results provide new mechanistic insights into the tumor-suppressive functions of SMAD7 in hepatocarcinogenesis.
- Published
- 2017