title: Reduced expression of transcriptional intermediary factor 1 gamma promotes metastasis and indicates poor prognosis of hepatocellular carcinoma.
abstract: Transcriptional intermediary factor 1 gamma (TIF1γ) may play either a potential tumor-suppressor or -promoter role in cancer. Here we report on a critical role of TIF1γ in the progression of hepatocellular carcinoma (HCC). Reduced expression of TIF1γ was detected in HCC, especially in advanced HCC tissues, compared to adjacent noncancerous tissues. HCC patients with low TIF1γ expression had shorter overall survival times and higher recurrence rates than those with high TIF1γ expression. Reduced TIF1γ expression was an independent and significant risk factor for recurrence and survival after curative resection. In HCC cells, TIF1γ played a dual role: It promoted tumor growth in early-stage HCC, but not in advanced-stage HCC, whereas it inhibited invasion and metastasis in both early- and advanced-stage HCC. Mechanistically, we confirmed that TIF1γ inhibited transforming growth factor-β/ Drosophila mothers against decapentaplegic protein (TGF-β/Smad) signaling through monoubiquitination of Smad4 and suppressed the formation of Smad2/3/4 complex in HCC cells. TGF-β-inducing cytostasis and metastasis were both inhibited by TIF1γ in HCC. We further proved that TIF1γ suppressed cyotstasis-related TGF-β/Smad downstream c-myc down-regulation, as well as p21/cip1 and p15/ink4b up-regulation in early-stage HCC. Meanwhile, TGF-β inducible epithelial-mesenchymal transition and TGF-β/Smad downstream metastatic cascades, including phosphatase and tensin homolog deleted on chromosome ten down-regulation, chemokine (CXC motif) receptor 4 and matrix metalloproteinase 1 induction, and epidermal growth factor receptor- and protein kinase B-signaling transactivation, were inhibited by TIF1γ. In addition, we found that the down-regulation of TIF1γ in HCC was caused by hypermethylation of CpG islands in the TIF1γ promoter, and demonstrated that the combination of TIF1γ and phosphorylated Smad2 was a more powerful predictor of poor prognosis.
  
  
  CONCLUSIONS
  TIF1γ regulates tumor growth and metastasis through inhibition of TGF-β/Smad signaling and may serve as a novel prognostic biomarker in HCC.
authors: Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors: Ze-yang
authors: ZY
authors: Ding
authors: Guan-nan
authors: GN
authors: Jin
authors: Wei
authors: W
authors: Wang
authors: Wei-xun
authors: WX
authors: Chen
authors: Yan-hui
authors: YH
authors: Wu
authors: Xi
authors: X
authors: Ai
authors: Lin
authors: L
authors: Chen
authors: Wan-guang
authors: WG
authors: Zhang
authors: Hui-fang
authors: HF
authors: Liang
authors: Arian
authors: A
authors: Laurence
authors: Ming-zhi
authors: MZ
authors: Zhang
authors: Pran K
authors: PK
authors: Datta
authors: Bixiang
authors: B
authors: Zhang
authors: Xiao-ping
authors: XP
authors: Chen
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D015536:Down-Regulation; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D011379:Prognosis; D051899:Smad2 Protein / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; C497782:SMAD2 protein, human; D051899:Smad2 Protein; C511956:TRIM33 protein, human; D014157:Transcription Factors; D016212:Transforming Growth Factor beta