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Decreased Expression of Programmed Death Ligand-L1 by Seven in Absentia Homolog 2 in Cholangiocarcinoma Enhances

Hao Zheng1,2,3,4,5, Wen-Juan Zheng1, Zhen-Guang Wang3,4,5

  • 1Department of General Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang, China.

Frontiers in Immunology
|February 14, 2022
PubMed

Insights

This study reveals how METTL14 regulates Siah2 expression via m6A modification, impacting PD-L1 levels and T cell responses in cholangiocarcinoma. Lower Siah2 levels may predict better outcomes with anti-PD1 immunotherapy.

Area of Science:

  • Epigenetics
  • Cancer Biology
  • Immunology

Background:

  • N6-methyladenosine (m6A) is a key post-transcriptional regulator.
  • Programmed death ligand 1 (PD-L1) promotes tumor immune evasion.
  • Seven in absentia homolog 2 (Siah2) is implicated in cancer progression.

Purpose of the Study:

  • To elucidate the role of the m6A-METTL14-Siah2-PD-L1 axis in cancer immunotherapy.
  • To investigate the regulatory mechanism of Siah2 by METTL14 in cholangiocarcinoma (CCA).

Main Methods:

  • Investigated m6A modification of Siah2 mRNA by METTL14.
  • Utilized co-immunoprecipitation to assess Siah2-PD-L1 interaction.
  • Performed in vitro and in vivo Siah2 knockdown experiments.
  • Analyzed human CCA specimens and patient immunotherapy response data.

Main Results:

  • METTL14 induces Siah2 expression in CCA by m6A modification of Siah2 mRNA, promoting its degradation via YTHDF2.
  • Siah2 interacts with PD-L1, promoting its K63-linked ubiquitination.
  • Siah2 knockdown sustains PD-L1 expression, inhibiting T cell expansion and cytotoxicity.
  • The METTL14-Siah2-PD-L1 axis is validated in human CCA.
  • Low Siah2 levels correlate with increased sensitivity to anti-PD1 immunotherapy.

Conclusions:

  • METTL14 epigenetically regulates Siah2 expression through m6A modification.
  • The METTL14-Siah2-PD-L1 pathway plays a significant role in regulating tumor immunity.
  • Siah2 is a potential predictive biomarker for anti-PD1 immunotherapy response in CCA.
Keywords:
METTL14N6-methyladenosinePD-L1Siah2immunotherapy

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