2210 DETECTION OF THE SECRETED PROSTATE CANCER BIOMARKER AGR2 IN VOIDED URINE

Abstract

You have accessJournal of UrologyProstate Cancer: Detection and Screening V1 Apr 20122210 DETECTION OF THE SECRETED PROSTATE CANCER BIOMARKER AGR2 IN VOIDED URINE Sue-Ing Quek, Melissa Ho, Michelle Loprieno, William Ellis, Lawrence True, Elizabeth Wayner, and Alvin Liu Sue-Ing QuekSue-Ing Quek Seattle, WA More articles by this author , Melissa HoMelissa Ho Seattle, WA More articles by this author , Michelle LoprienoMichelle Loprieno Seattle, WA More articles by this author , William EllisWilliam Ellis Seattle, WA More articles by this author , Lawrence TrueLawrence True Seattle, WA More articles by this author , Elizabeth WaynerElizabeth Wayner Seattle, WA More articles by this author , and Alvin LiuAlvin Liu Seattle, WA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2385AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Prostate cancer is currently screened by an imperfect test of measuring the blood level of prostate-specific antigen (PSA/KLK3). This test has a false positive rate of nearly 75% with the result that many men would have to undergo an unnecessary biopsy. PSA is not a good cancer biomarker because it is not cancer-specific. Better markers are needed. Comparative transcriptomics between sorted CD26+ cancer cells and CD26+ luminal cells identified AGR2 (anterior gradient 2) as one of the highest up-regulated genes encoding secreted proteins in cancer. Overexpression in primary tumors was verified by tissue microarray analysis: AGR2 expression was absent in non-cancer (n=111) and BPH (n=288) vs. elevated in cancer (n=659) and PIN (n=68). AGR2 encodes a 19-kDa secreted protein that might be found in voided urine. METHODS Mouse monoclonal antibodies (mAbs) were generated against recombinant AGR2. One antibody pair, P1G4 (IgG1) to capture and P3A5 (IgG2a) to detect, showed good performance characteristics in a sandwich ELISA. This assay could measure AGR2 at sub ng/ml quantities. RESULTS AGR2 was detected in tissue digestion media of tumor specimens (and not that of non-cancer specimens) and culture media of AGR2-secreting prostate cancer cell lines. Specificity of the newly obtained mAbs was validated by immunoprecipitation, frozen tissue immunohistochemistry, and Western blot analysis. An AGR2 ELISA was developed with P1G4 and P3A5. Voided urine samples were collected from pre-operative cancer patients, and urinary protein was desalted and concentrated by spin filtration. The amount of AGR2 detected was scored as pg/100 μg urinary protein, and then converted to pg/ml urine. This ELISA was able to detect AGR2 in urine, ranging from 3.6 to 181 pg/ml, in an initial cohort of samples. Higher values appeared to correlate with tumor size. AGR2 was not detected in the urine of healthy control and a bladder cancer patient as bladder cancer cells do not overexpress AGR2. CONCLUSIONS For prostate cancer, an AGR2 urine test could be used for diagnosis and screening. The data showed that developing such a test for clinical application is viable because AGR2 is specific to cancer cells, and is secreted into urine. Since urine is a waste product, large volumes can be collected repeatedly and concentrated for testing. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e891 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Sue-Ing Quek Seattle, WA More articles by this author Melissa Ho Seattle, WA More articles by this author Michelle Loprieno Seattle, WA More articles by this author William Ellis Seattle, WA More articles by this author Lawrence True Seattle, WA More articles by this author Elizabeth Wayner Seattle, WA More articles by this author Alvin Liu Seattle, WA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...