%0 Journal Article
%T Antiproliferative and Apoptotic Effects of a Specific Antiprostate Stem Cell Single Chain Antibody on Human Prostate Cancer Cells
%A Foroogh Nejatollahi
%A Soghra Abdi
%A Mahdi Asgharpour
%J Journal of Oncology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/839831
%X Prostate stem cell antigen (PSCA) is a highly glycosylated cell surface protein which is overexpressed in several malignancies including prostate, pancreas, and urinary bladder cancers. Tumor suppression has been reported by anti-PSCA antibody. Small and high affinity single chain antibodies (scFv) have been introduced as effective agents for cancer immunotargeting approaches. In the present study, we used a phage antibody display library of scFv and selected two antibodies against two immunodominant epitopes of PSCA by panning process. The reactivity of the scFvs for the corresponding epitopes was determined by phage ELISA. The binding specificity of antibodies to PSCA-expressing prostate cancer cell line, DU-145, was analyzed by flow cytometry. The antiproliferative and apoptotic induction effects were evaluated by MTT and Annexin-V assays, respectively. Results represented functional scFv C5-II which could bind specifically to DU-145 cells and significantly inhibited the proliferation of these cells (61%) with no effect on PSCA-negative cells. The antibody also induced apoptosis in the PSCA expressing cells. The percentage of the apoptotic cells after 24£¿hrs of exposure to 500£¿scFv/cell was 33.80%. These results demonstrate that the functional anti-PSCA scFv C5-II has the potential to be considered as a new agent for targeted therapy of prostate cancer. 1. Introduction Prostate stem cell antigen is a cell surface antigen belonging to the Thy-1/Ly-6 family of glycosylphosphatidylinositol (GPI) anchored proteins [1]. PSCA expression in normal tissues has shown to be predominantly prostate specific. However, less expression of PSCA has also been detected in other normal tissues including placenta, stomach, and kidney [2]. Elevated levels of PSCA have been reported in over 80% of prostate cancer specimens and in all cases of bone metastasis from prostate cancer patients [3]. The overexpression of PSCA has also been reported in most bladder and pancreatic cancers [4¨C6]. In the cases of prostate cancer, high levels of PSCA expression have widely been correlated with high Gleason score, advanced tumor stage, seminal vesicle involvement, progression to androgen-independent disease, and bone metastasis [7¨C10]. Although the role of PSCA in intercellular signaling has been shown, little is known about the regulatory mechanism or biological functions of PSCA [11, 12]. It has been suggested that PSCA could act as both tumor suppressor and tumor promoting antigen based on tumor type, the microenvironment of the tumor, and the crosstalk between PSCA and other
%U http://www.hindawi.com/journals/jo/2013/839831/