Cancer proteome and metabolite changes linked to SHMT2

PLoS One. 2020 Sep 9;15(9):e0237981. doi: 10.1371/journal.pone.0237981. eCollection 2020.

Abstract

Serine hydroxymethyltransferase 2 (SHMT2) converts serine plus tetrahydrofolate (THF) into glycine plus methylene-THF and is upregulated at the protein level in lung and other cancers. In order to better understand the role of SHMT2 in cancer a model system of HeLa cells engineered for inducible over-expression or knock-down of SHMT2 was characterized for cell proliferation and changes in metabolites and proteome as a function of SHMT2. Ectopic over-expression of SHMT2 increased cell proliferation in vitro and tumor growth in vivo. Knockdown of SHMT2 expression in vitro caused a state of glycine auxotrophy and accumulation of phosphoribosylaminoimidazolecarboxamide (AICAR), an intermediate of folate/1-carbon-pathway-dependent de novo purine nucleotide synthesis. Decreased glycine in the HeLa cell-based xenograft tumors with knocked down SHMT2 was potentiated by administration of the anti-hyperglycinemia agent benzoate. However, tumor growth was not affected by SHMT2 knockdown with or without benzoate treatment. Benzoate inhibited cell proliferation in vitro, but this was independent of SHMT2 modulation. The abundance of proteins of mitochondrial respiration complexes 1 and 3 was inversely correlated with SHMT2 levels. Proximity biotinylation in vivo (BioID) identified 48 mostly mitochondrial proteins associated with SHMT2 including the mitochondrial enzymes Acyl-CoA thioesterase (ACOT2) and glutamate dehydrogenase (GLUD1) along with more than 20 proteins from mitochondrial respiration complexes 1 and 3. These data provide insights into possible mechanisms through which elevated SHMT2 in cancers may be linked to changes in metabolism and mitochondrial function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antifungal Agents / pharmacology
  • Apoptosis
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism*
  • Cell Proliferation
  • Gene Expression Regulation, Neoplastic*
  • Glycine Hydroxymethyltransferase / antagonists & inhibitors
  • Glycine Hydroxymethyltransferase / genetics
  • Glycine Hydroxymethyltransferase / metabolism*
  • HeLa Cells
  • Humans
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology*
  • Metabolome*
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mitochondria / pathology
  • Protein Interaction Domains and Motifs
  • Proteome / analysis*
  • Serine / metabolism*
  • Sodium Benzoate / pharmacology
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays

Substances

  • Antifungal Agents
  • Biomarkers, Tumor
  • Proteome
  • Serine
  • Glycine Hydroxymethyltransferase
  • SHMT protein, human
  • Sodium Benzoate

Grants and funding

This work was supported by grants to MFM from Canadian Cancer Society, Innovation Program; Canada Foundation for Innovation; Genome Canada’s Pan Canadian Proteomics Centre; and the Garron Family Cancer Centre, Hospital for Sick Children. MFM was supported by a Canada Research Chair.