A juxtacrine/paracrine loop between C-Kit and stem cell factor promotes cancer stem cell survival in epithelial ovarian cancer

Cell Death Dis. 2019 May 28;10(6):412. doi: 10.1038/s41419-019-1656-4.

Abstract

Receptors tyrosine kinase (RTK) enable normal and tumor cells to perceive and adapt to stimuli present in the microenvironment. These stimuli, also known as growth factors, are important molecular cues actively supporting cancer stem cell (CSC) self-renewal and viability. Since in epithelial ovarian cancer (EOC) the expression of c-Kit (CD117) has been identified as a CSC hallmark, we investigated the existence of a tumor growth-promoting loop between c-Kit and its ligand Stem Cell Factor (SCF). SCF exists as a soluble or transmembrane protein and through c-Kit interaction regulates cell viability, proliferation, and differentiation both in physiological and pathological conditions. High amounts of SCF were found in the ascitic effusions collected from EOC patients. While tumor cells and CSC only expressed the membrane-associated SCF isoform, both secreted and membrane-bound isoforms were expressed by tumor-associated macrophages (TAM, here shown to be M2-like) and fibroblasts (TAF). Circulating monocytes from EOC-bearing patients and healthy donors did not express both SCF isoforms. However, monocytes isolated from healthy donors produced SCF upon in vitro differentiation into macrophages, irrespectively of M1 or M2 polarization. In vitro, both SCF isoforms were able to activate the Akt pathway in c-Kit+ cells, and this effect was counteracted by the tyrosine kinase inhibitor imatinib. In addition, our results indicated that SCF could help c-Kit+ CSC survival in selective culture conditions and promote their canonical stemness properties, thus indicating the possible existence of a juxtacrine/paracrine circuit in EOC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Carcinoma, Ovarian Epithelial / genetics
  • Carcinoma, Ovarian Epithelial / metabolism*
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • Cell Survival / genetics
  • Female
  • Fibroblasts / metabolism
  • HEK293 Cells
  • Humans
  • Imatinib Mesylate / pharmacology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism
  • Neoplastic Stem Cells / drug effects
  • Neoplastic Stem Cells / metabolism*
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism*
  • Paracrine Communication / genetics
  • Phosphatidylinositol 3-Kinase / metabolism
  • Phosphorylation
  • Protein Isoforms / chemistry
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / chemistry
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-kit / chemistry
  • Proto-Oncogene Proteins c-kit / metabolism*
  • Signal Transduction / genetics
  • Stem Cell Factor / genetics
  • Stem Cell Factor / metabolism*
  • Tumor Microenvironment / drug effects
  • Tumor Microenvironment / genetics
  • Tumor Microenvironment / immunology

Substances

  • Antineoplastic Agents
  • Protein Isoforms
  • Protein Kinase Inhibitors
  • Stem Cell Factor
  • Imatinib Mesylate
  • Phosphatidylinositol 3-Kinase
  • KIT protein, human
  • Proto-Oncogene Proteins c-kit
  • Proto-Oncogene Proteins c-akt