Comprehensive in silico analysis of glycosylphosphatidylinositol- anchored protein (GPI-AP) related genes expression profiles in human normal and cancer tissues.

Abstract

In human cells, there are more than 146 glycosylphosphatidylinositol-anchored proteins (GPI-APs), including receptors, ligands, adhesion molecules and enzymes. The proteins are associated with membrane microdomains called lipid rafts through GPI, and plays a variety of important biological functions. At present, plenty of studies have been carried out on the biosynthesis of GPI-APs. The biosynthesis of GPI-APs requires at least 20 steps, and more than 40 GPI biosynthetic genes have been identified. However, it remains unclear how expression of GPI-AP related genes is regulated in normal and cancer tissues. In this study, we utilized gene expression data from both the TCGA database and GTEx portal to analysis the gene expression involved in GPI-AP biosynthesis and encoding GPI-APs in normal and cancer tissues. In order to perform a comprehensive analysis, we employed the GlycoMaple, a tool that is specifically designed to analyze glycosylation pathways. The results showed that compared with normal tissues, the expression of genes involved in GPI-AP biosynthesis in cancer tissues such as early glioma, glioblastoma multiforme, pancreatic cancer, testicular germ cell carcinoma, skin primary cutaneous melanoma and skin metastatic cutaneous melanoma, was changed significantly. Particularly, the expression of PIGY in these six cancers was increased. In addition, the expression of CD14, a GPI-AP gene, was increased in these six cancers. The expression of GAS1, GPC2 and GPC4 was increased only in early glioma and glioblastoma multiforme indicating that some GPI-APs such as GAS1 can be used as biomarkers of glioma. This study provides new insights into the expression of GPI-AP related genes in normal and cancer tissues, and lays a solid foundation for the development of GPI-APs as biomarkers.