Expression of GP88 (progranulin) in serum of prostate cancer patients is associated with Gleason scores and overall survival

Thomas Greither,1,* Kersten Fischer,2,* Gerit Theil,2 Marios Marcou,1,2 Hans-Juergen Holzhausen,3 Katrin Weigelt,4 Ginette Serrero,5,6 David Hicks,5 Binbin Yue,5 Paolo Fornara,2 Bernd Wullich,4 Helge Taubert,4 Sven Wach,4 Verena Lieb4 1Center for Reproductive Medicine and Andrology, Martin Luther University Halle-Wittenberg, Halle, Germany; 2Department of Urology, Martin Luther University Halle-Wittenberg, Halle, Germany; 3Department of Pathology, Martin Luther University Halle-Wittenberg, Halle, Germany; 4Department of Urology and Pediatric Urology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; 5A&G Pharmaceutical Inc., Columbia, Maryland, USA; 6Program in Oncology, University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, Maryland, USA *These authors contributed equally to this work Background: GP88/Progranulin is a well-recognized cell growth promoter in different cancers, and elevated serum GP88 levels have been described as negative prognostic factor in breast cancer. However, serum levels in prostate cancer (PCa) patients have not yet been studied. Material and Methods: We analyzed serum GP88 levels by enzyme immunosorbent assay and correlated them with clinicopathological parameters in PCa patients. PCa patients were separated into two groups based on the serum GP88 median level (low ≤44.56 ng/mL or high >44.56 ng/mL) and according to their median age (younger ≤66 years or elder patients >66 years). Results: Low serum GP88 levels were more often detected in younger patients and high levels in elder patients (P=0.018; Fisher’s exact test). PCa patients were separated into three groups, Gleason score (GS) ≤6; GS=7; and GS≥8. In receiver operating characteristic analyses, we could distinguish GS≤6 from GS=7 [area under the curve (AUC): 0.646; P=0.018] and GS≤6 from GS≥8 (AUC: 0.629; P=0.048) but not GS=7 from GS≥8. For survival analysis, GP88 levels were separated into two groups by an optimized cutoff value of 36.92 ng/mL. Using this GP88 stratification, all PCa patients and younger patients with a low serum GP88 level had a significantly better overall survival compared with patients with higher serum GP88 levels (log-rank test P=0.010 and P=0.024). Conclusion: Serum GP88 levels are significantly different depending on age and GS, and they are associated with the prognosis of PCa patients. Keywords: GP88, progranulin, prostate cancer, Gleason score