Reciprocal regulation by TLR4 and TGF-β in tumor-initiating stem-like cells
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
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
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 8

Induction of TLR4/NANOG/YAP1/IGF2BP3 pathway components in human HCC.

Options: View larger image (or click on image) Download as PowerPoint
Induction of TLR4/NANOG/YAP1/IGF2BP3 pathway components in human HCC. (A...
(A) TLR4, NANOG, IGF2BP3, and YAP1 protein levels are increased in HCC specimens from patients with HCV infection without or with alcoholism, as compared with cirrhotic or healthy livers. (B) Immunofluorescent microscopy demonstrates higher expression of NANOG, TLR4, YAP1, and IGF2BP3, which are often colocalized in patient HCC specimens, as compared with normal liver. Original magnification, ×200. (C) Immunofluorescent microscopy demonstrates increased expression of NANOG, YAP1, and IGF2BP3, which are often colocalized in HCC specimens from patients with nonalcoholic steatohepatitis (NASH), as compared with normal liver. p-SMAD3 staining is conversely reduced in HCC. Original magnification, ×200. (D) The log OR (and 95% CI) of patient death within 5 years from initial diagnosis for HCC patients is increased for those with positive IGF2BP3 or/and YAP1 immunoreactivity, as compared with those with negative IGF2BP3 and YAP1 immunoreactivity (red line).