Increased Circulating Level of the Survival Factor GP88 (Progranulin) in the Serum of Breast Cancer Patients When Compared to Healthy Subjects

INTRODUCTION: GP88 (PC-Cell Derived Growth Factor, progranulin) is a glycoprotein overexpressed in breast tumors and involved in their proliferation and survival. Since GP88 is secreted, an exploratory study was established to compare serum GP88 level between breast cancer patients (BC) and healthy volunteers (HV). METHODS: An IRB approved prospective study enrolled 189 stage 1–4 BC patients and 18 HV. GP88 serum concentration was determined by immunoassay. RESULTS: Serum GP88 level was 28.7 + 5.8 ng/ml in HV and increased to 40.7 + 16.0 ng/ml (P = 0.007) for stage 1–3 and 45.3 + 23.3 ng/ml (P = 0.0007) for stage 4 BC patients. There was no correlation between the GP88 level and BC characteristics such as age, race, tumor grade, ER, PR and HER-2 expression. CONCLUSION: These data suggest that serial testing of serum GP88 levels may have value as a circulating biomarker for detection, monitoring and follow up of BC.