Abstract LB-102: Cilengitide induces apoptosis and reduces cell viability in breast cell lines.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Brain metastasis from breast cancer incidence is increasing as better control of primary disease leads to longer patient survival. Current therapy for brain metastases is whole brain radiotherapy, stereotactic radiosurgery, or surgical resection. Due to the relative impermeability of the blood brain barrier, not may chemotherapeutics can effectively target these metastases in the brain. Cilengitide, an αVβ3 and αVβ5 inhibitor, is a cyclic RGD containing pentapeptide. Cilengitide has been shown to cross the blood brain barrier and accumulate to appreciable levels in brain tissue in a phase 2 trial in glioblastoma. αVβ3 integrins play a role in angiogenesis, but also are expressed on tumor cells and play a role in proliferation, survival, and invasion. The purpose of these experiments was to examine the role of cilengitide in cell proliferation and survival in a panel of breast cancer cell lines. T-47D, MCF-7, MDA-MB-468, and MDA-MB-231 cell lines were examined. Initially, cells were counted after 1hr of treatment with various cilengitide doses. Next, cells were treated for 4 days with the same cilengitide doses and a proliferation assay (MTS) was performed. These assays showed that at short and long timepoints, cilengitide treatment can have a significant effect on cell viability and proliferation. T-47D cells were particularly sensitive to cilengitide at both short and long timepoints, while MDA-MB-468 cells were particularly resistant. The other cell lines showed an intermediate phenotype. In an attempt to understand the fate of cells following treatment, apoptosis was measured by Annexin V/Propidium Iodide staining and flow cytometry after 48hr treatment with various cilengitide doses. This assay showed increased apoptotic and dead cells, which increased in a dose dependent fashion for all cell lines except MDA-MB-468 cells which again showed no response to cilengitide treatment. As was seen previously, T-47D cells were the most sensitive, followed by MCF-7 cells and then MDA-MB-231 cells. Cells were also examined for Integrin β3 expression by western blot, with target identified in all cell lines. In conclusion, we have observed that cilengitide has both immediate and lasting effects on breast cell line viability and proliferation. Not all cell lines responded equally however, and the reason for these differences is not fully understood. Cilengitide target expression level may play a role in this process, and apoptosis appears to be possible mechanism for cilengitide mediated cell death in these cell lines. Cilengitide appears to be a good candidate for personalized therapy, but a more complete understanding of its effects could identify a patient subpopulation that is most likely to respond favorably to cilengitide. Citation Format: James D. Perry, David Peereboom, Arnab Chakravarti, Tim Lautenschlaeger. Cilengitide induces apoptosis and reduces cell viability in breast cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-102. doi:10.1158/1538-7445.AM2013-LB-102