Inhibitory role of Smad7 in hepatocarcinogenesis in mice and in vitro
Publication in refereed journal


摘要Smad7 is a principal inhibitor of the TGFβ-Smad signalling pathway. We have investigated the functional significance of Smad7 in hepatocellular carcinoma (HCC). Smad7 knockout (KO) and wild-type (WT) mice were injected with diethylnitrosamine (DEN) to induce HCC. The effects of Smad7 on cellular features were examined in HCC cells, using a Smad7 over-expression or deletion approach. Signalling pathway components modulated by Smad7 in HCC were evaluated using luciferase reporter assay and co-immunoprecipitation. Smad7 was down-regulated in human HCCs compared with the adjacent normal tissues (p < 0.001). Smad7 KO mice were more susceptible to DEN-induced HCC than WT mice (78% versus 22%, p < 0.05). HCCs from KO mice displayed a greater proliferation activity (p < 0.05) and a reduced apoptotic index compared with WT littermates (p < 0.05). Deletion of Smad7 promoted cell proliferation in primary cultured HCC cells. In addition, over-expression of Smad7 in HCC cell lines markedly suppressed cell growth (p < 0.0001) and colony formation (p < 0.01). Cell cycle analysis revealed an increase in the G1 phase and a reduction in the S-phase populations, accompanied by up-regulation of p27Kip1 and down-regulation of cyclin D1. Smad7 increased cell apoptosis (p < 0.01) by mediating an intrinsic [caspase-9, caspase-3 and poly(ADP-ribose) polymerase] apoptotic pathway. Moreover, Smad7 inhibited NF-κB signalling by interacting with TAB2, an upstream activator of NF-κB, and inhibited TGFβ signalling by suppressing phosphorylation of Smad3. In conclusion, loss of Smad7 enhances susceptibility to HCC. Smad7 suppresses HCC cell growth by inhibiting proliferation and G1-S phase transition and inducing apoptosis through attenuation of NF-κB and TGFβ signalling. Smad7 acts as a potential tumour suppressor in liver. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
著者Wang J., Zhao J., Chu E.S.H., Mok M.T.S., Go M.Y.Y., Man K., Heuchel R., Lan H.Y., Chang Z., Sung J.J.Y., Yu J.
期刊名稱Journal of Pathology
出版社John Wiley & Sons Inc.
出版地United States
頁次441 - 452
關鍵詞animal model, hepatocellular carcinoma, Smad7, tumour suppressor

上次更新時間 2020-25-10 於 02:20