Identification of Differentially Expressed Proteins from Prostate Cancer Cell Lines by Fluorescence 2-D Difference Gel Electrophoresis (2-D DIGE)

Abstract

Prostate cancer (PCa) is the most common cancer diagnosis and the second leading cause of cancer-related deaths in males worldwide. Prostate-specific antigen (PSA) is the only biomarker widely utilized in diagnosis and management of PCa patients. However, PSA lacks sensitivity and specificity for diagnosis, which leads to false-negative and false-positive test results. PSA cannot differentiate indolent from aggressive prostate disease, which leads to over-treatment of many patients with associated side-effects. Furthermore, PSA is unable to identify tumors which are likely to become unresponsive to treatment at an early stage. Thus, there is an urgent need for identification of biomarkers which will improve the diagnosis and management of PCa. In this study, to explore the specific proteins for PCa, fluorescence 2-D Difference Gel Electrophoresis (2-D DIGE) was performed in 3 prostate cancer cell lines (LNCaP, PC-3, and DU145) with the comparison of normal prostate cells (RWPE-1). The separated proteins with a fold difference greater than two and presence in all both normal and cancer cells were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF). Expression profiling between prostate cancer cell lines and normal prostate cells revealed 33 protein candidates with expression difference (P < 0.05) and over 2-fold change. The expression levels of peroxiredoxin 3 (PRDX3), keratin 8 (KRT8), and heat shock protein 60 (HSP60) were verified with Western blot in the normal epithelial cells RWPE-1 and prostate cancer cell lines LNCaP, PC-3, DU145 as well 25 pairs of patient-matched prostate tissues. The proteins are aberrantly expressed in human prostate cancer suggesting their implication in the development and progression of this malignancy.