Abstract 4410: Apoptosis in Ovarian Cancer Cells Induced by Polyclonal Antibodies to Secreted Frizzle-related Protein 2

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objectives: We have previously discovered a novel angiogenesis factor, secreted frizzle-related protein 2 (SFRP2), that is strongly expressed in many human tumors including ovarian carcinoma. SFRP2 protects against endothelial cell apoptosis, and induces endothelial tube formation and migration. We hypothesize that in addition to its paracrine role in stimulating angiogenesis, SFRP2 also has a direct effect in tumor cells, and therefore blocking SFRP2 will induce ovarian cancer apoptosis. Methods: Protein expression of SFRP2 in ovarian cancer cells: SKOV-3 and OVCA −3 ovarian cancer cells were cultured in McCoy's medium with 10% bovine serum albumin. Whole cell protein lysates were obtained and Western blot analysis was performed probing for SFRP2. Apoptosis assay: SKOV3 cells were plated in 96 well plates and allowed to attach overnight. Rabbit polyclonal antibody to SFRP2 (SFRP2 Ab) was run through a column with a saline buffer to remove the sodium azide preservative. Cells were treated with antibody in 1:10, 1:100, and 1:1000 concentrations. McCoy's culture medium with 1% saline was used as a negative control. Cells were incubated at 37°C for 48 hours. Apoptosis was measured by the activity of cleaved caspase-3 by using a caspase-specific fluorogenic substrate. Statistical analysis was performed with a two-tailed student's t-test. Results: SKOV-3 and OVCA-3 ovarian cancer cells strongly express SFRP2 on Western Blot analysis. When SKOV-3 cells were treated with polyclonal antibody to SFRP2 (1:10) there was a 47% increase in apoptosis as compared with negative controls (control = 1509 RFU ± 50, SFRP2 Ab =2221 RFU ± 39, n=4 for both groups, p<0.0001). Conclusions: SFRP2 is a protein endogenously expressed by ovarian carcinoma. Blocking SFRP2 with a polyclonal antibody induces apoptosis in SKOV-3 ovarian cancer cell line, suggesting that this protein may be a potential target in the treatment of ovarian cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4410.