The heparan sulfate proteoglycan syndecan-1 regulates colon cancer stem cell function via a focal adhesion kinase-Wnt signaling axis

FEBS J. 2021 Jan;288(2):486-506. doi: 10.1111/febs.15356. Epub 2020 May 25.

Abstract

In colon cancer, downregulation of the transmembrane heparan sulfate proteoglycan syndecan-1 (Sdc-1) is associated with increased invasiveness, metastasis, and dedifferentiation. As Sdc-1 modulates signaling pathways relevant to stem cell function, we tested the hypothesis that it may regulate a tumor-initiating cell phenotype. Sdc-1 small-interfering RNA knockdown in the human colon cancer cell lines Caco2 and HT-29 resulted in an increased side population (SP), enhanced aldehyde dehydrogenase 1 activity, and higher expression of CD133, LGR5, EPCAM, NANOG, SRY (sex-determining region Y)-box 2, KLF2, and TCF4/TCF7L2. Sdc-1 knockdown enhanced sphere formation, cell viability, Matrigel invasiveness, and epithelial-to-mesenchymal transition-related gene expression. Sdc-1-depleted HT-29 xenograft growth was increased compared to controls. Decreased Sdc-1 expression was associated with an increased activation of β1-integrins, focal adhesion kinase (FAK), and wingless-type (Wnt) signaling. Pharmacological FAK and Wnt inhibition blocked the enhanced stem cell phenotype and invasive growth. Sequential flow cytometric SP enrichment substantially enhanced the stem cell phenotype of Sdc-1-depleted cells, which showed increased resistance to doxorubicin chemotherapy and irradiation. In conclusion, Sdc-1 depletion cooperatively enhances activation of integrins and FAK, which then generates signals for increased invasiveness and cancer stem cell properties. Our findings may provide a novel concept to target a stemness-associated signaling axis as a therapeutic strategy to reduce metastatic spread and cancer recurrence. DATABASES: The GEO accession number of the Affymetrix transcriptomic screening is GSE58751.

Keywords: extracellular matrix; glycosaminoglycan; syndecans; tumor-initiating cells; xenograft.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AC133 Antigen / genetics
  • AC133 Antigen / metabolism
  • Aldehyde Dehydrogenase 1 Family / genetics
  • Aldehyde Dehydrogenase 1 Family / metabolism
  • Animals
  • Benzothiazoles / pharmacology
  • Caco-2 Cells
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Colonic Neoplasms / drug therapy
  • Colonic Neoplasms / genetics*
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology
  • Epithelial Cell Adhesion Molecule / genetics
  • Epithelial Cell Adhesion Molecule / metabolism
  • Focal Adhesion Kinase 1 / antagonists & inhibitors
  • Focal Adhesion Kinase 1 / genetics*
  • Focal Adhesion Kinase 1 / metabolism
  • Gene Expression Regulation, Neoplastic*
  • HT29 Cells
  • Humans
  • Indoles / pharmacology
  • Integrin beta1 / genetics
  • Integrin beta1 / metabolism
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism
  • Mice
  • Nanog Homeobox Protein / genetics
  • Nanog Homeobox Protein / metabolism
  • Neoplastic Stem Cells / drug effects
  • Neoplastic Stem Cells / metabolism*
  • Neoplastic Stem Cells / pathology
  • Oligopeptides / pharmacology
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Sex-Determining Region Y Protein / genetics
  • Sex-Determining Region Y Protein / metabolism
  • Spheroids, Cellular / drug effects
  • Spheroids, Cellular / metabolism
  • Spheroids, Cellular / pathology
  • Sulfonamides / pharmacology
  • Syndecan-1 / antagonists & inhibitors
  • Syndecan-1 / genetics*
  • Syndecan-1 / metabolism
  • Transcription Factor 7-Like 2 Protein / genetics
  • Transcription Factor 7-Like 2 Protein / metabolism
  • Tumor Burden / drug effects
  • Wnt Signaling Pathway / drug effects*
  • Xenograft Model Antitumor Assays

Substances

  • AC133 Antigen
  • Benzothiazoles
  • EPCAM protein, human
  • Epithelial Cell Adhesion Molecule
  • IWP-2 compound
  • Indoles
  • Integrin beta1
  • Itgb1 protein, human
  • KLF2 protein, human
  • Kruppel-Like Transcription Factors
  • LGR5 protein, human
  • N-methyl-N-(3-((2-(2-oxo-2,3-dihydro-1H-indol-5-ylamino)-5-trifluoromethyl-pyrimidin-4-ylamino)-methyl)-pyridin-2-yl)-methanesulfonamide
  • NANOG protein, human
  • Nanog Homeobox Protein
  • Oligopeptides
  • PROM1 protein, human
  • RNA, Small Interfering
  • Receptors, G-Protein-Coupled
  • SDC1 protein, human
  • SRY protein, human
  • Sex-Determining Region Y Protein
  • Sulfonamides
  • Syndecan-1
  • TCF7L2 protein, human
  • Transcription Factor 7-Like 2 Protein
  • arginyl-glycyl-aspartic acid
  • Aldehyde Dehydrogenase 1 Family
  • Focal Adhesion Kinase 1
  • PTK2 protein, human