O-glycosylated clusterin as a sensitive marker for diagnosing early stages of prostate cancer.

Abstract

BACKGROUND:

Prostate-specific antigen (PSA) has been the most popular diagnostic marker for prostate cancer. The frequent occurrence of low PSA values (<10 ng/ml) in patients with highly suspicious prostate cancer, however, has undermined the accuracy of clinical examinations. The aim of this study was to develop a better resolution for diagnosing prostate cancer to overcome the disadvantage of PSA.

METHODS:

We focused on the glycosylation status of patients' serum proteins and conducted comprehensive lectin microarray analyses to characterize N- and O-glycans using sera from prostate cancer and benign prostatic diseases. Next, we retrieved candidate serum proteins with characteristic glycan structures using lectin-immobilized beads and identified them by quantitative mass spectrometry using a technique referred to as isobaric tag for relative and absolute quantitation (iTRAQ) labeling. Finally, we constructed a new assay to quantify a candidate glycoprotein with the newly identified glycans.

RESULTS:

Lectin microarray analyses revealed that sera from patients with prostate cancer had a higher affinity for Jacalin, Amaranthus caudatus (ACA) lectin, and Maclura pomifera (MPA) lectin, compared with that from patients with benign prostatic diseases and normal subjects, suggesting that O-glycosylated proteins are more abundant in sera from patients with prostate cancer. Then, serum glycoproteins preferentially adsorbed onto Jacalin-Agarose as well as biotin-ACA/and biotin-MPA/streptavidin-immobilized magnetic beads were isolated, labeled with iTRAQ, and identified using quantitative mass spectrometry. It was found that the ACA- and MPA-recognizable clusterin was more enriched in patients' sera from prostate cancer compared with those from benign prostatic diseases. Following this discovery, we constructed a Luminex-based assay to quantify O-glycosylated clusterin, in which total serum clusterin was first captured on anti-clusterin antibody-immobilized beads, and then clusterin-associated O-glycans were determined by the pair of biotin-MPA and streptavidin-phycoerythrin. When PSA values registered less than 10 ng/ml, the corresponding serum level of MPA-recognized clusterin determined by this assay was beneficial for distinguishing the patients with prostate cancer from the patients with benign prostatic disease.

CONCLUSION:

For PSA values that measure less than 10 ng/ml, the serum O-glycosylated clusterin level can be a complementary indicator for the malignancy of prostate cancer.

• Authors: Saiko Kazuno, Tsutomu Fujimura, Makoto Fujime, Yoshiki Miura, Takashi Ueno
• Journal: The Prostate (Prostate) Vol. 81 Issue 3 Pg. 170-181 (02 2021) ISSN: 1097-0045 [Electronic] United States
• PMID: 33347638 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2020 Wiley Periodicals LLC.

Chemical References

• Biomarkers
• Clusterin
• Glycoproteins
• Lectins
• Polysaccharides
• Prostate-Specific Antigen

Topics

• Biomarkers (blood)
• Cell Line, Tumor
• Clusterin (blood, chemistry, metabolism)
• Glycoproteins (blood)
• Glycosylation
• Humans
• Lectins (blood)
• Male
• Neoplasm Grading
• Polysaccharides (blood)
• Prostate-Specific Antigen (blood)
• Prostatic Neoplasms (blood, metabolism, pathology)
• Protein Array Analysis