983 PSMA EXPRESSION ON THE MITOCHONDRIAL MEMBRANE OF PROSTATE CANCER CELLS LEADS TO A FOLATE-DEPENDENT INCREASE IN CELLULAR PROLIFERATION

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research (V)1 Apr 2013983 PSMA EXPRESSION ON THE MITOCHONDRIAL MEMBRANE OF PROSTATE CANCER CELLS LEADS TO A FOLATE-DEPENDENT INCREASE IN CELLULAR PROLIFERATION Benjamin Ristau, Jessica Cummings, Denise O'Keefe, and Dean Bacich Benjamin RistauBenjamin Ristau Pittsburgh, PA More articles by this author , Jessica CummingsJessica Cummings Pittsburgh, PA More articles by this author , Denise O'KeefeDenise O'Keefe Pittsburgh, PA More articles by this author , and Dean BacichDean Bacich Pittsburgh, PA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.565AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Data-driven metabolomic analysis of cancer cell lines has identified glycine consumption as a critical mediator for de novo purine synthesis. Glycine generation relies on the folate-dependent one carbon pathway. Enzymes associated with mitochondrial one-carbon metabolism are strongly associated with proliferation and higher mortality rates in breast cancer. Prostate-Specific Membrane Antigen (PSMA), a unique folate-hydrolase, is an independent marker of prostate cancer aggressiveness, although the underlying mechanism is unclear. Expression of PSMA on the mitochondrial membrane may amplify one-carbon metabolism by increasing mitochondrial folate levels and giving prostate cancer cells a growth advantage. METHODS Stable BPH-1 cell lines expressing PSMA or GFP control, LNCaP GFP-shRNA (targeting native PSMA expression), and LNCaP GFP control lines were generated. PSMA expression in the cells was confirmed via Western blotting on both whole cells and on mitochondria isolated using the Mitochondrial Extraction Kit (Miltenyi Biotec). Enzymatic function of PSMA was confirmed by ion exchange chromatography for glutamate carboxypeptidase type 2 (GCP2) activity in whole cell and mitochondrial preparations. Mitochondrial folate content was assessed using the Lactobacillus Casei microbiologic folate assay. MTT assays were used to determine cell growth rates. Finally, total cellular and mitochondrial glycine levels were measured by ELISA in all four transduced cell lines. RESULTS In all cells expressing PSMA, 50% of the full-length protein localized to the mitochondrial membrane. GCP2 activity in whole cell and mitochondrial preparations corresponded to amount of PSMA present. Total cellular folate content was nearly 2-fold higher in BPH-1 PSMA expressing cells as compared to BPH-1 GFP cells (p<0.001). Mitochondrial folate was increased in BPH-1 PSMA expressing cells compared to BPH-1 GFP cells (2.24 v 0.6 pg/mcg, p <0.001). In all four cell lines, PSMA expressing cells grew significantly faster than their non-expressing counterparts (p < 0.001). CONCLUSIONS Patients with high serum folate levels have tumors that proliferate significantly faster than patients with low folate levels. Our results suggest that PSMA increases total cellular folate predominantly by increasing mitochondrial folate content. These increased mitochondrial folate pools may supercharge mitochondrial one-carbon metabolism, thereby driving cell proliferation and cancer progression. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e403-e404 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Benjamin Ristau Pittsburgh, PA More articles by this author Jessica Cummings Pittsburgh, PA More articles by this author Denise O'Keefe Pittsburgh, PA More articles by this author Dean Bacich Pittsburgh, PA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...