Clinical & Experimental Metastasis

, Volume 19, Issue 4, pp 291–299

GPI-specific phospholipase D mRNA expression in tumor cells of different malignancy

  • Xiaotong He
  • Melanie-Jane Hannocks
  • Ian Hampson
  • Georg Brunner
Article

DOI: 10.1023/A:1015545407700

Cite this article as:
He, X., Hannocks, MJ., Hampson, I. et al. Clin Exp Metastasis (2002) 19: 291. doi:10.1023/A:1015545407700

Abstract

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is a highly specific enzyme whose only known substrate is the GPI anchor of cell surface proteins. GPI-PLD measurements, however, are technically difficult since the enzyme is expressed at low levels in cells and tissues, and serum contains large amounts of inactive, latent GPI-PLD interfering with protein-based assays. We have therefore developed a semi-quantitative RT-PCR method to measure mRNA expression of all known GPI-PLD isoforms in cells and tissues. In human ovarian cancer cell lines, GPI-PLD mRNA expression correlated with GPI-PLD enzyme activity and with the shedding of the GPI-anchored tumor and prognostic markers, urokinase receptor and CA125, from the cell surface. This supports a potential role for this enzyme in the generation of circulating prognostic markers in malignant tumors. Similarly, in human epithelial cells of the skin, GPI-PLD mRNA expression increased with tumor progression. Whereas normal keratinocytes did not express significant amounts of GPI-PLD mRNA, expression was dramatically induced by serum in immortalized HaCaT keratinocytes and constitutively high and independent of serum in tumorigenic A431 epidermoid carcinoma cells. In addition, GPI-PLD expression was significantly increased in highly malignant, H-ras-transfected murine bladder carcinoma cells as compared to the low malignant, non-transfected parental cells. The competitive RT-PCR described here represents the first quantitative assay specific for cellular GPI-PLD isoforms, and our in vitro analyses suggest that GPI-PLD expression might be associated with tumor malignancy.

glycosylphosphatidylinositol GPI-anchored proteins GPI-specific phospholipase D protein shedding RT-PCR tumor marker tumor progression 

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Xiaotong He
    • 1
    • 2
  • Melanie-Jane Hannocks
    • 1
  • Ian Hampson
    • 3
  • Georg Brunner
    • 2
  1. 1.Department of Cancer Research, Fachklinik HornheideUniversity of MünsterGermany
  2. 2.School of Biological SciencesUniversity of ManchesterUK
  3. 3.Department of MedicineUniversity of ManchesterUK