Sialyl Lewis antigens are selectin ligands involved in leukocyte trafficking and cancer metastasis. Biosynthesis of these selectin ligands occurs by the sequential actions of several glycosyltransferases in the Golgi apparatus following synthesis of the protein backbone in the endoplasmic reticulum. In this study, we examine how the synthesis of sialyl Lewis a (sLea) is regulated in prostatic cells and identify a mucin that carries this glycotope. We treat human prostatic cells including one normal and three cancerous cells with histone deacetylase inhibitors, valproic acid, tricostatin A (TSA), and suberoylanilide hydroxamic acid (SAHA), and then monitor the expression of sLea. We have found that SAHA enhances the production of sLea in normal prostatic RWPE-1 cells but not prostatic cancer cells. Employing siRNA technology and co-immunoprecipitation, we show that the sLea is associated with MUC1, which is confirmed by confocal immunofluorescence microscopy and proximity ligation assay. The SAHA-induced production of sLea in RWPE-1 cells is resulted from upregulation of B3GALT1 gene via enhancement of acetylated histone-3 and histone-4. Interestingly, PC3 and LNCaP C-81 cells do not produce detectable amounts of sLea despite expressing high levels of B3GALT1. However, the MUC1-associated sLea is generated in these cells after introduction of MUC1 cDNA. We conclude that the synthesis of sLea is controlled by not only peptide backbone of the glycoprotein but also glycoprotein-specific glycosyltransferases involved in the synthesis of sLea. Further, the SAHA induction of this selectin ligand in normal prostatic cells may pose a potentially serious side effect of this drug recently approved by the US Food and Drug Administration.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)