Modulation of Melanotransferrin and Transferrin Receptor 1 (TFRC)- and CD44-based Signaling for TFRC Up-regulation in Human Melanoma Cells

Anticancer Res. 2017 Jun;37(6):3001-3007. doi: 10.21873/anticanres.11654.

Abstract

Background: The human melanoma cell line IGR-1 was used for the detection and regulation of both melanotransferrin (MTf) and transferrin receptor 1 (TFRC, CD71). While the function in iron transport of the TFRC is well documented the functional importance of MTf is not yet fully understood. Due to the up-regulation of TFRC by hyaluronan (HA) some components and aspects of CD44 signaling were investigated.

Materials and methods: The cell-surface proteins MTf, TFRC and ERBB2 receptor tyrosine kinase 2 (ERBB2) were detected by immunoluminescent technique using different polyclonal and monoclonal antibodies. Ionomycin was used to inhibit β-catenin/T-cell-specific transcription factor (TCF) association, essential in HA-CD44-ERBB2 signaling.

Results: MTf, was found to be resistant to phosphatidylinositol-specific phospholipase C. However, MTf as well as TFRC were sensitive to partial proteolytic degradation by pronase E and trypsin. The expression of MTf was shown to be up-regulated by mannose-6-phosphate and that of TFRC by HA. Ionomycin at 10 μM inhibited TFRC up-regulation. However, at 50 μM it induced a 7.5-fold increase of TFRC concentration.

Conclusion: Our results suggest that human melanoma cells are able to up-regulate TFRC expression using HA/CD44 signaling. The whole pathway comprises of the sequence: HA/CD44, neural Wiskott-Aldrich syndrome protein (N-WASP), ERBB2, β-catenin/TCF, c-MYC and TFRC. Since β-catenin is also known to be a component of wingless/Int-1-Frizzled signaling that also leads to transcriptional c-MYC activation, the pathway found here might be alternatively used by melanoma cells for iron supply, necessary for cell proliferation.

Keywords: HA/CD44 signalling; Melanotransferrin (MTf); human melanoma cells; immunoluminescence; transferrin receptor 1 (TFRC).

MeSH terms

  • Antigens, CD / metabolism*
  • Cell Line, Tumor
  • Humans
  • Hyaluronan Receptors / metabolism*
  • Hyaluronic Acid / pharmacology
  • Mannosephosphates / pharmacology
  • Melanoma / metabolism*
  • Receptors, Transferrin / metabolism*
  • Ribosomal Proteins / metabolism*
  • Signal Transduction / drug effects
  • Up-Regulation / drug effects

Substances

  • Antigens, CD
  • CD44 protein, human
  • CD71 antigen
  • Hyaluronan Receptors
  • Mannosephosphates
  • Receptors, Transferrin
  • Ribosomal Proteins
  • metanephros-derived tubulogenic factor, human
  • mannose-6-phosphate
  • Hyaluronic Acid