A “Sweeter” PSA Test
Looking for a small chemical change — the addition of a form of sugar to PSA molecules — makes it easier for scientists to tell if a man has aggressive cancer. “Glycosylation means attaching sugar; it is a common modification of proteins that is involved in many cellular functions,” says Daniel W. Chan, Ph.D., who directs the Clinical Chemistry Division and the Center for Biomarker Discovery, and co-directs the Pathology Core Lab. “It also happens in cancer.” Studies have shown that abnormal glycosylations occur during the series of molecular changes that lead to cancer. PSA is a “glycoprotein,” meaning that it has sugar attached to it at the molecular level.
“In this study, we analyzed blood samples from men with prostate cancer. We measured levels of glycoproteins, and of molecules with a form of sugar called fucose added to them, and then checked them against the Gleason score of the prostate tumor. We found that the fucosylated PSA was elevated and correlated with tumor Gleason scores.” In looking at cancers with a Gleason score greater than 6, “both fucosylated PSA and the ratio of fucosylated PSA were better at predicting aggressive cancer than standard PSA. Our data suggested that fucosylated PSA has the potential to be used as a biomarker to differentiate aggressive from non-aggressive prostate cancers.” This work was funded by the National Cancer Institute, and was published in Theranostics.