Abstract 273: Molecular markers promoting metastases to the brain via EMT: Genes, proteins, and functional analysis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Brain metastasis is the most common cause of mortality and morbidity of many cancers and occurs in more than 40% of patients. The metastatic cascade entails an orderly sequence of steps enabling tumor cells to migrate from the primary tumor and colonize at secondary locations. The underlying mechanisms of metastatic dissemination to the brain remain to be defined. However, In order to achieve this metastatic potential a cancer cell may go through a cellular reprogramming process, namely epithelial-to-mesenchymal transition (EMT), and its counterpart mesenchymal-to-epithelial transition (MET), by acquiring multiple genetic alterations and a stem cell like phenotype. We hypothesized that EMT would play a crucial role in brain metastasis. In order to achieve our goal we studied the expression of markers of EMT, MET, and stem cells in metastatic brain tumor samples. Microarray analysis of metastatic tumors was also done using a plate form of 17,000 genes. Furthermore, functional analysis establishing the metastatic phenotype of cancer cells towards a cerebral environment was also demonstrated using metastatic cell lines. Our results demonstrated that the expressions of EMT markers (Snail, TWIST, pSTAT3, NFkB), as well as the mesenchymal marker Vimentin, were present in metastatic tumor samples. The stem cell marker CD44 was also highly expressed. Gene expression analysis established the high presence of transcriptional factors associated with differentiation and reprogramming. Lastly, Immunofluorescence analysis demonstrated the presence of the mesenchymal marker Vimentin in brain tumor specimens. Tumor cells grown in astrocytic media displayed an increased cell proliferation, as well as enhanced S-phase cell cycle entry using an EDU incorporation technique. Migration of primary tumor cells was significantly enhanced in astrocytic media as evidenced by scratch wound migration. Furthermore, the tumor cells have a greater affinity for astrocytic media as demonstrated by chemotatic migratory tests. Moreover, co-culture analysis of primary tumor cells with astrocytic cells shows amicable mutual growth with Immunofluorescence demonstrating cell-to-cell interaction via E-Cadherin. In conclusion results of this study suggests that reprogramming via EMT/MET plays a crucial step in brain metastasis, and that the cerebral milieu provides a suitable microenvironment for metastatic cells to grow and disseminate. Citation Format: Dhruve S. Jeevan, Sudeepta Sridhara, Alex Braun, Raj Murali, Meena Jhanwar-Uniyal. Molecular markers promoting metastases to the brain via EMT: Genes, proteins, and functional analysis. [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 273. doi:10.1158/1538-7445.AM2013-273