Translocator protein (TSPO) is an 18 kDa mitochondrial membrane protein, first identified as a second binding site for benzodiazepine. Elevated levels of TSPO have been associated with breast cancer progression and with increased proliferation in cancer cells whereas TSPO ligands, PK11195 and Ro5-4864, which may serve as TSPO antagonists, inhibit proliferation in multiple cancer cell lines. Whether TSPO actually contributes to breast cancer progression is not known. In this study, the impact of TSPO up-regulation in breast epithelial cells is being assessed using a 3D Matrigel culture system. MCF10A mammary epithelial cells form well-polarized acini structures with a hollow lumen when grown in 3D Matrigel, whereas expression of oncogenes in MCF10A cells often induces phenotypes such as increased acinar size and filling of the lumen. In this study, a pool of stable TSPO expressing breast epithelial MCF-10A cells has been constructed. TSPO overexpressing MCF-10A cells when grown in 3D matrigel formed larger acini compared with control acini; and displayed abnormal lumen formation. Such a disruption of normal mammary epithelial morphogenesis by TSPO may resemble an early stage breast lesion leading to breast cancer. Immunofluorescent staining revealed increased levels of Ki-67 (a proliferative marker) in TSPO overexpressing acini compared with control acini, suggesting that TSPO promoted proliferation during mammary epithelial morphogenesis. TSPO ligands, including PK11195 and RO5-4864, inhibited proliferation of stable TSPO over-expressing MCF-10A cells in 2D plastic culture. Studies on the impact of TSPO ligands on the morphogenesis of MCF10A and breast cancer cells in 3D culture are being conducted.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4240. doi:1538-7445.AM2012-4240