Reciprocal regulation by TLR4 and TGF-β in tumor-initiating stem-like cells
Chia-Lin Chen, … , Joseph H. Jeong, Keigo Machida
Chia-Lin Chen, … , Joseph H. Jeong, Keigo Machida
Published June 10, 2013
Citation Information: J Clin Invest. 2013;123(7):2832-2849. https://doi.org/10.1172/JCI65859.
View: Text | PDF | Retraction
Research Article

Reciprocal regulation by TLR4 and TGF-β in tumor-initiating stem-like cells

Abstract

Tumor-initiating stem-like cells (TICs) are resistant to chemotherapy and associated with hepatocellular carcinoma (HCC) caused by HCV and/or alcohol-related chronic liver injury. Using HCV Tg mouse models and patients with HCC, we isolated CD133+ TICs and identified the pluripotency marker NANOG as a direct target of TLR4, which drives the tumor-initiating activity of TICs. These TLR4/NANOG–dependent TICs were defective in the TGF-β tumor suppressor pathway. Functional oncogene screening of a TIC cDNA library identified Yap1 and Igf2bp3 as NANOG-dependent genes that inactivate TGF-β signaling. Mechanistically, we determined that YAP1 mediates cytoplasmic retention of phosphorylated SMAD3 and suppresses SMAD3 phosphorylation/activation by the IGF2BP3/AKT/mTOR pathway. Silencing of both YAP1 and IGF2BP3 restored TGF-β signaling, inhibited pluripotency genes and tumorigenesis, and abrogated chemoresistance of TICs. Mice with defective TGF-β signaling (Spnb2+/– mice) exhibited enhanced liver TLR4 expression and developed HCC in a TLR4-dependent manner. Taken together, these results suggest that the activated TLR4/NANOG oncogenic pathway is linked to suppression of cytostatic TGF-β signaling and could potentially serve as a therapeutic target for HCV-related HCC.

Authors

Chia-Lin Chen, Hidekazu Tsukamoto, Jian-Chang Liu, Claudine Kashiwabara, Douglas Feldman, Linda Sher, Steven Dooley, Samuel W. French, Lopa Mishra, Lydia Petrovic, Joseph H. Jeong, Keigo Machida

×

Figure 5

Validation of Yap1 and Igf2bp3 as TIC oncogenes.

Options: View larger image (or click on image) Download as PowerPoint
Validation of Yap1 and Igf2bp3 as TIC oncogenes. (A) The number of col...
(A) The number of colonies formed by TICs in soft agar is moderately reduced by lentiviral transduction of shRNA against Yap1 or Igf2bp3 but largely abrogated when knocking down both. Stat3 silencing has no effects. *P < 0.05, **P < 0.01. (B) Self-renewal ability, as assessed by spheroid formation assay, is reduced in sh-Yap1/sh-Igf2bp3–transduced TICs. Serial spheroid-forming capacity is also reduced by dual transduction of sh-Yap1 and sh-Igf2bp3. *P < 0.05. (C) Immunoblot analysis demonstrates induced expression of IGF2BP3 and YAP1 in TICs and effective knockdown by respective shRNA. (D) Transduction of Ifg2bp3 shRNA, but not that of Yap1 shRNA, modestly reduces subcutaneous tumor growth by the TICs from the Ns5a Tg mice in NOG mice, while transduction of both shRNA clearly abrogates the growth at the later 3 time points. Representative photos of NOG mice carrying TIC-derived tumors are shown to depict an appreciable reduction of tumor size by Igf2bp3 and Yap1 silencing. *P < 0.05, **P < 0.01 versus scrambled shRNA group.