Abstract 3623: Monoclonal antibody against the 4th extracellular domain of N-cadherin affects FGF2 mediated pathways in prostate cancer

Abstract

Abstract Introduction: Fibroblast growth factor 2 (FGF2) has been reported to synergize with N-cadherin, a cell surface marker of epithelial mesenchymal transition (EMT), to enhance migration and invasion in breast cancer and other cancers. Recent studies from our group suggested that N-cadherin promotes castration resistance and metastasis in prostate cancer. In addition, our studies showed that antibodies against N-cadherin ectodomains blocked prostate cancer invasion and castration resistant growth. To investigate the mechanism of action of N-cadherin antibodies in prostate cancer cells, we seek to determine the contribution of the different N-cadherin domains in promoting invasion and growth in prostate cancer cells, with particular focus on interaction with FGF2. Methods: Chimeric constructs, in which a N-cadherin domain was swapped with an E-cadherin domain, were generated and ectopically expressed in androgen dependent prostate cancer cell line LNCaP. The following combinations were made: 1/ NE: N-cadherin ectodomains linked to E-cadherin cytoplasmic domain (NE), 2/ EN: the reverse of NE, 3/ NEN: swapping N-cadherin ectodomain 4 for that of E-cadherin. Full length N-cadherin and empty vector sublines served as positive and negative controls. All cell lines were assayed for invasion and growth in androgen depleted media in combination with recombinant FGF2, FGF2 neutralizing antibody and N-cadherin antibodies. Results: Ectopic expression of N-cadherin in N-cadherin negative cells result in a 5-fold increase of FGF2 secreted in the media. In vitro studies have shown that the addition of recombinant FGF2 enhanced invasion by 56%± 0.04 in N-cadherin positive cells while treatment with FGF2 neutralizing antibody resulted in a 65%± 0.03 reduction in invasion. Chimeric cell lines which harbor extracellular domain 4 of N-cadherin, N and NE cell lines, showed >56%± 0.11 enhanced invasion to the addition of recombinant FGF2 while EN, NEN, and control cell lines did not. Monoclonal antibodies developed against regions in the extracellular domain of N-cadherin block the response to recombinant FGF2 with 2A9 (antibody raised against extracellular domain 4) being the least responsive. Conclusions: These studies suggest that the relationship between N-cadherin and FGF2 is involved in prostate cancer progression. Therapeutic targeting of N-cadherin with monoclonal antibodies, alone or in combination with other drugs targeting those potentially involved in downstream pathways may have significant clinical benefit. Future experiments include in vivo models where chimeric cell lines will be implanted in mice as xenografts, and will be monitored for tumor growth, local invasion, and metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3623. doi:10.1158/1538-7445.AM2011-3623