iScience (Mar 2023)

LIN28 and histone H3K4 methylase induce TLR4 to generate tumor-initiating stem-like cells

  • Juan Carlos Hernandez,
  • Chia-Lin Chen,
  • Tatsuya Machida,
  • Dinesh Babu Uthaya Kumar,
  • Stanley M. Tahara,
  • Jared Montana,
  • Linda Sher,
  • Jake Liang,
  • Jae U. Jung,
  • Hidekazu Tsukamoto,
  • Keigo Machida

Journal volume & issue
Vol. 26, no. 3
p. 106254

Abstract

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Summary: Chemoresistance and plasticity of tumor-initiating stem-like cells (TICs) promote tumor recurrence and metastasis. The gut-originating endotoxin-TLR4-NANOG oncogenic axis is responsible for the genesis of TICs. This study investigated mechanisms as to how TICs arise through transcriptional, epigenetic, and post-transcriptional activation of oncogenic TLR4 pathways. Here, we expressed constitutively active TLR4 (caTLR4) in mice carrying pLAP-tTA or pAlb-tTA, under a tetracycline withdrawal-inducible system. Liver progenitor cell induction accelerated liver tumor development in caTLR4-expressing mice. Lentiviral shRNA library screening identified histone H3K4 methylase SETD7 as central to activation of TLR4. SETD7 combined with hypoxia induced TLR4 through HIF2 and NOTCH. LIN28 post-transcriptionally stabilized TLR4 mRNA via de-repression of let-7 microRNA. These results supported a LIN28-TLR4 pathway for the development of HCCs in a hypoxic microenvironment. These findings not only advance our understanding of molecular mechanisms responsible for TIC generation in HCC, but also represent new therapeutic targets for the treatment of HCC.

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