Altered glycosylation pattern allows the distinction between prostate-specific antigen (PSA) from normal and tumor origins

• Published in: Glycobiology (Oxford) 2003-06, Vol.13 (6), p.457-470
• Main Authors: Peracaula, Rosa, Tabarés, Glòria, Royle, Louise, Harvey, David J., Dwek, Raymond A., Rudd, Pauline M., de Llorens, Rafael
• Format: Article
• Language: English
• Subjects: 2-aminobenzamide; 2AB; ABS; almond meal α-fucosidase; AMF; Animals; Arthrobacter ureafaciens sialidase; benign prostate hyperplasia; BKF; bovine kidney fucosidase; bovine serum albumin; bovine testes β-galactosidase; BPH; BSA; BTG; Carbohydrate Sequence; Cell Line, Tumor; Chromatography, High Pressure Liquid; column volume; DHT; dihydrotestosterone; electrospray ionization; ELISA; Enzyme-Linked Immunosorbent Assay; ESI; FBS; fetal bovine serum; Gene Expression; glucose units; Glycosylation; high-performance liquid chromatography; HPLC; Humans; jack bean β-N-acetylhexosaminidase; JBH; LNCaP cells; MALDI; Male; mass spectrometry; matrix-assisted laser desorption-ionization; Mice; Molecular Sequence Data; N-glycosylation; NANI; NMR; normal-phase; nuclear magnetic resonance; Oligosaccharides - analysis; PAGE; PBS; PCa; phosphate buffered saline; polyacrylamide gel electrophoresis; prostate cancer; prostate carcinoma; prostate-specific antigen; Prostate-Specific Antigen - analysis; Prostate-Specific Antigen - chemistry; Prostate-Specific Antigen - metabolism; Prostatic Neoplasms - chemistry; PSA; S. pneumoniae hexosaminidase; SDS; Semen - chemistry; Sequence Analysis, Protein; sodium dodecyl sulfate; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; SPG; SPH; Streptococcus pneumoniae galactosidase; Streptococcus pneumoniae sialidase recombinant in E. coli; time-of-flight; TOF; tumor marker; WAX; weak anion exchange
• ISSN: 0959-6658; 1460-2423; 1460-2423
• DOI: 10.1093/glycob/cwg041

Prostate-specific antigen (PSA) is a glycoprotein secreted by prostate epithelial cells. PSA is currently used as a marker of prostate carcinoma because high levels of PSA are indicative of a tumor situation. However, PSA tests still suffer from a lack of specificity to distinguish between benign prostate hyperplasia and prostate cancer. To determine whether PSA glycosylation could provide a means of differentiating between PSA from normal and tumor origins, N-glycan characterization of PSA from seminal fluid and prostate cancer cells (LNCaP cell line) by sequencing analysis and mass spectrometry was carried out. Glycans from normal PSA (that correspond to low and high pI PSA fractions) were sialylated biantennary complex structures, half of them being disialylated in the low pI PSA fraction and mostly monosialylated in the high pI PSA. PSA from LNCaP cells was purified to homogeneity, and its glycan analysis showed a significantly different pattern, especially in the outer ends of the biantennary complex structures. In contrast to normal PSA glycans, which were sialylated, LNCaP PSA oligosaccharides were all neutral and contained a higher fucose content. In 10–15% of the structures fucose was linked α1-2 to galactose, forming the H2 epitope absent in normal PSA. GalNAc was increased in LNCaP glycans to 65%, whereas in normal PSA it was only present in 25% of the structures. These carbohydrate differences allow a distinction to be made between PSA from normal and tumor origins and suggest a valuable biochemical tool for diagnosis and follow-up purposes.