The fluorescence intensity measured from LNCaP cells was nearly identical to the values measured from isotype control or untreated cells (c) and (d). 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 [4C6]. 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 [7C10]. Although the role of PSCA in intercellular signaling has Rabbit Polyclonal to NUP160 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 molecules [12]. Preclinical data have suggested PSCA as a potential target antigen for both diagnostic and therapeutic applications. Blocking of PSCA with monoclonal antibodies in some mouse models of prostate and pancreas cancers has resulted in the inhibition of tumor growth and prevention of metastasis [13C15]. Recombinant antibodies have recently shown great promise in the replacement of monoclonal antibodies in different Succinyl phosphonate trisodium salt medical areas such as immunotherapy against human malignancies [16C19]. Single chain fragment variable (scFv) antibodies are one of the most popular formats of the recombinant antibodies [20]. Advantages of scFvs over the intact antibodies including smaller size, fast penetration and tight binding to target tissue, fast clearance from the body, and better pharmacokinetic properties as well as fully human origin have offered scFvs as desirable tools for both the imaging and therapeutic purposes [21C24]. In the present study, we isolated specific scFv antibodies against immunodominant epitopes of PSCA and evaluated their inhibitory effects on PSCA-expressing cancer cells using cell proliferation and Annexin-V assays. 2. Materials and Methods 2.1. Selection of Anti-PSCA scFv A phage antibody display library of scFv was Succinyl phosphonate trisodium salt developed as described previously [25, 26]. The library was phage-rescued using M13KO7 helper phage and the specific scFv antibodies were isolated by panning process. Briefly, peptides as epitopes (amino acids 50C64 and 67C81 of PSCA) were coated overnight on immunotubes (Nunc, Roskilde, Denmark). The phage-rescued supernatant (1010 PFU/mL) diluted with blocking solution was added to the tubes and incubated for 1?h at room temperature. After adding the log phase TG1 bacteria, the bacterial pellet was grown on Succinyl phosphonate trisodium salt 2TY-ampicillin agar plates. Four rounds of panning were performed to isolate specific antibodies against the epitopes. PCR was performed on the clones obtained after panning to investigate the presence of the desired band corresponding to the scFv insert and DNA Succinyl phosphonate trisodium salt fingerprinting with Mva-I restriction enzyme revealed the common patterns. One of the clones with the most frequent pattern was selected against each epitope and phage-rescued for further evaluations. 2.2. Measurement of scFv Concentration Concentrations of the selected scFvs were measured using phage concentration determination. The selected phage-rescued supernatant (10?in a logarithmic growth phase and incubated with shaking for 1?h at 37C. Serially diluted cultures were plated onto 2TY-ampicillin agar plates. Single-chain Fv concentration was then calculated by counting the number of colonies per dilution. 2.3. Phage ELISA Peptides (100?test to compare the means Succinyl phosphonate trisodium salt of percentages of cell growth between.