Generation and characterization of monoclonal antibodies to prostate secretory protein

Abstract

Monoclonal antibodies (MAbs) were produced against a highly purified preparation of prostate secretory protein (PSP) isolated from normal seminal plasma. Fifteen antibodies were selected for further evaluation based on their strong reactivity and specificity for PSP. All the MAbs had a specificity for prostate epithelial cells and none reacted to any of a variety of normal tissues as determined by immunoperoxidase staining. Six of the MAbs were selected for further immunohistochemical evaluation based on their ability to recognize different antigenic determinants. Using competitive binding immunoassays, a variety of overlapping specificities were observed with at least 2 distinct epitopes identified. Although some staining variability was noted, the 6 antibodies, in general, gave the same pattern of tissue reactivity. Both the normal prostate and the benign prostate hyperplastic ductal epithelial cells stained intensely, with 78 to 100% and 50-100% of the cells staining, respectively. The number and often the staining intensity of the tumor cells decreased as the tumor became more undifferentiated. Approximately 40 to 100% and 15 to 70% of the tumor cells stained in the moderately-differentiated and well-differentiated carcinoma tissues, respectively, whereas either no staining was observed or less than 20% of the tumor cells stained in the poorly-differentiated and undifferentiated tumors. Most of the metastatic prostate tumors showed either no staining or scattered staining in a few cells (i.e., less than 20%).

A novel monoclonal antibody 107-1A4 with high prostate specificity: generation, characterization of antigen expression, and targeting of human prostate cancer xenografts

“…Direct ELISAs were used to determine whether Mab 107-1A4 reacted to any of several known prostate associated proteins: PSA, 2 PSP-94, 9 and PAP (prostatic alkaline phosphatase). 10 These were puri®ed in our laboratory by standard methods and identity con®rmed by Western blot analysis.…”

“…PSP-94 was prepared at 0.5 mg/mL and the anti-PSP Mabs PSP-6 and PSP-19 (gifts of Dr G Wright) were used as the positive controls. 9 PAP was prepared at 2 mg/mL and anti-PAP Mab and polyclonal antibodies (Sigma, St. Louis, MO) were used as the positive controls. For these ELISAs, 100 mL of each protein preparation was immobilized to the wells of the EIA/RIA high-binding 96-well plates (Costar) for 1 h at room temperature.…”

Comparison of prostate secretory protein with prostate specific antigen and prostatic acid phosphatase as a serum biomarker for diagnosis and monitoring patients with prostate carcinoma

“…Previously, we reported the generation and characterization of a series of monoclonal antibodies against PSP and the development of a two-site monoclonal antibody (MAb)-based immunoradiometric assay for measuring serum PSP [ 16,171. Based on this assay, the serum PSP concentrations in both BPH and prostate cancer patients were found to be significantly elevated as compared with those in age-matched normal males.…”

Factor H Binding to Bone Sialoprotein and Osteopontin Enables Tumor Cell Evasion of Complement-mediated Attack

“…In addition, BSP peptides are potent inhibitors of breast cancer cell adhesion to bone (82,83). OPN is expressed in breast cancer (4,7,16,23), as well as in prostate cancer (21), thyroid cancer (84), skin cancer (85), and several other types of cancer (6,86,87).…”