NNMT contributes to high metastasis of triple negative breast cancer by enhancing PP2A/MEK/ERK/c-Jun/ABCA1 pathway mediated membrane fluidity

Cancer Lett. 2022 Oct 28:547:215884. doi: 10.1016/j.canlet.2022.215884. Epub 2022 Aug 19.

Abstract

Elucidating the mechanism for high metastasis capacity of triple negative breast cancers (TNBC) is crucial to improve treatment outcomes of TNBC. We have recently reported that nicotinamide N-methyltransferase (NNMT) is overexpressed in breast cancer, especially in TNBC, and predicts poor survival of patients undergoing chemotherapy. Here, we aimed to determine the function and mechanism of NNMT on metastasis of TNBC. Additionally, analysis of public datasets indicated that NNMT is involved in cholesterol metabolism. In vitro, NNMT overexpression promoted migration and invasion of TNBCs by reducing cholesterol levels in the cytoplasm and cell membrane. Mechanistically, NNMT activated MEK/ERK/c-Jun/ABCA1 pathway by repressing protein phosphatase 2A (PP2A) activity leading to cholesterol efflux and membrane fluidity enhancement, thereby promoting the epithelial-mesenchymal transition (EMT) of TNBCs. In vivo, the metastasis capacity of TNBCs was weakened by targeting NNMT. Collectively, our findings suggest a new molecular mechanism involving NNMT in metastasis and poor survival of TNBC mediated by PP2A and affecting cholesterol metabolism.

Keywords: Cholesterol metabolism; Epithelial-mesenchymal transition; Lung metastasis; Methylation potential; Protein phosphatase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter 1 / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Cholesterol
  • Epithelial-Mesenchymal Transition
  • Humans
  • Membrane Fluidity
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Neoplasm Metastasis
  • Nicotinamide N-Methyltransferase / metabolism
  • Protein C / metabolism
  • Protein C / therapeutic use
  • Triple Negative Breast Neoplasms* / metabolism

Substances

  • ABCA1 protein, human
  • ATP Binding Cassette Transporter 1
  • Cholesterol
  • Mitogen-Activated Protein Kinase Kinases
  • Nicotinamide N-Methyltransferase
  • NNMT protein, human
  • Protein C