Liver cancer initiation requires translational activation by an oncofetal regulon involving LIN28 proteins
Meng-Hsiung Hsieh, … , John T. Powers, Hao Zhu
Meng-Hsiung Hsieh, … , John T. Powers, Hao Zhu
Published June 14, 2024
Citation Information: J Clin Invest. 2024;134(15):e165734. https://doi.org/10.1172/JCI165734.
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Research Article Hepatology

Liver cancer initiation requires translational activation by an oncofetal regulon involving LIN28 proteins

Abstract

It is unknown which posttranscriptional regulatory mechanisms are required for oncogenic competence. Here, we show that the LIN28 family of RNA-binding proteins (RBPs), which facilitate posttranscriptional RNA metabolism within ribonucleoprotein networks, is essential for the initiation of diverse oncotypes of hepatocellular carcinoma (HCC). In HCC models driven by NRASG12V/Tp53, CTNNB1/YAP/Tp53, or AKT/Tp53, mice without Lin28a and Lin28b were markedly impaired in cancer initiation. We biochemically defined an oncofetal regulon of 15 factors connected to LIN28 through direct mRNA and protein interactions. Interestingly, all were RBPs and only 1 of 15 was a Let-7 target. Polysome profiling and reporter assays showed that LIN28B directly increased the translation of 8 of these 15 RBPs. As expected, overexpression of LIN28B and IGFBP1-3 was able to genetically rescue cancer initiation. Using this platform to probe components downstream of LIN28, we found that 8 target RBPs were able to restore NRASG12V/Tp53 cancer formation in Lin28a/Lin28b-deficient mice. Furthermore, these LIN28B targets promote cancer initiation through an increase in protein synthesis. LIN28B, central to an RNP regulon that increases translation of RBPs, is important for tumor initiation in the liver.

Authors

Meng-Hsiung Hsieh, Yonglong Wei, Lin Li, Liem H. Nguyen, Yu-Hsuan Lin, Jung M. Yong, Xuxu Sun, Xun Wang, Xin Luo, Sarah K. Knutson, Christina Bracken, George Q. Daley, John T. Powers, Hao Zhu

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Figure 5

LIN28B regulates RPS5 translation through direct mRNA binding.

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LIN28B regulates RPS5 translation through direct mRNA binding. (A) eCLIP...
(A) eCLIP data show LIN28B-binding regions on RPS5 mRNA. Red marks under the gene indicate the location of consensus LIN28B-binding motifs (GGAGA). Deletion (Δ) and mutation (MT) of consensus motifs were introduced to prevent LIN28B binding. Exon 1, 2, 3, and 3′ UTR sequences were inserted into the Renilla 3′ UTR region. (B) WB analysis of RPS5 and LIN28B in Huh7 and SNU308 cell lines. Numbers below the boxes show relative intensities. (C) Renilla luciferase activity promoted by RPS5 exon 1, exon 2, exon 3, and 3′ UTR reporters in LIN28B siRNA knockdown (n = 3) versus control Huh7 cells (n = 3). (D) Renilla luciferase activity promoted by RPS5 exon 1, exon 2, exon 3, and 3′ UTR reporters in LIN28B overexpression (n = 3) versus control SNU308 cells (n = 3). (E and F) Renilla luciferase activity promoted by WT RPS5 sequences compared with deletion and mutation containing reporters in control (blue) and LIN28B siRNA knockdown (red) Huh7 cells (n = 3) (E) and in control overexpression (green) and LIN28B overexpression (orange) SNU308 cells (n = 3) (F). One-way ANOVA was performed. **P < 0.01; ***P < 0.001; ****P < 0.0001.