TGF-β1 secreted by hepatocellular carcinoma induces the expression of the Foxp3 gene and suppresses antitumor immunity in the tumor microenvironment.
OBJECTIVE
The purpose of this study was to explore the mechanisms of TGF-β1 mediated immunosuppression in tumor stroma.


METHODS
The expression of TGF-β1 was investigated in Huh7, Hep 3B, SGC-7901, Eca-109 and Hepa1-6 cell lines using immunofluorescence. Knocked-down TGF-β1 of the Hepa1-6 cell line was established through lentivirus-based RNA interference. The interference efficiency of the TGF-β1 gene was tested by real-time PCR and ELISA; the expression of Foxp3, IFN-γ and CD83 in CD4(+), CD8(+) or dendritic cells was examined via flow cytometry; and the tumorigenic ability of the cancer cells was investigated in the animal experiments.


RESULTS
The diverse digestive cancer cells were found to secrete TGF-β1, mRNA of which was knocked down by 78 % thanks to lentivirus-based interference in Hepa1-6 cells. Flow cytometry showed that CD4(+)CD25(+)Foxp3(+) regulatory T cells significantly increased in hepatocellular carcinoma patients when compared with those in the healthy controls. The supernatant from Hepa1-6 cells and recombinant TGF-β1 significantly induced the expression of Foxp3 gene in vitro, while that from sh TGF-β1 Hepa1-6 cells restored it. Hepa1-6 cells inhibited IFN-γ and CD83 expression in CD8(+) or dendritic cells by secreting TGF-β1. The animal experiments indicated that the knockdown TGF-β1 gene impaired the tumorigenic ability of Hepa1-6 cells.


CONCLUSIONS
TGF-β1, expressed in cancer cells, might be a potential therapeutic target for cancer treatment.
The Department of Gastroenterology of Zhongshan Hospital, Fudan University, 180 Fenglin Rd, Shanghai, 200032, People's Republic of China.
Yi
Y
Wang
Bin
B
Deng
Wenqing
W
Tang
Taotao
T
Liu
Xizhong
X
Shen
D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000276:immunology* / Q000378:metabolism; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
D014408:Biomarkers, Tumor; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D053773:Transforming Growth Factor beta1