Inflammation plays a pivotal role in the progression of solid malignant tumor with studies showing that the presence of specific inflammatory-immune cells, such as macrophages, at the tumor site leads to poor prognosis. M1 polarized macrophages secrete pro-inflammatory chemokines and cytokines which induce an epithelial to mesenchymal transition (EMT) in tumor cells; a process where epithelial cells acquire mesenchymal traits, thus facilitating tissue infiltration and consequent metastasis. EMT as a marker of cancer progression is understudied in thyroid cancer. In our present study, we evaluated the crosstalk between the macrophages and the epithelial cells in the thyroid tumor microenvironment with the use of an in vitro model system consisting of an immortalized thyroid cell line (Nthy-ori 3-1), three papillary cancer cell lines (BCPAP, 8505C and TPC-1) and one follicular cancer cell line (CGTHW-1). We observed the halt in proliferation of the thyroid cancer cells as the epithelial cells differentiate into mesenchymal cells under the influence of activated macrophage conditioned media. We also observed a statistically significant (p<0.05) upregulation of migration and invasion of thyroid tumor cells in presence of macrophage conditioned media. Using nuclear and cytoplasmic extracts from the thyroid cancer cell lines, we observed that EMT markers including E-cadherin, β-catenin, vimentin, NFk-B, snail, slug and twist are modulated in response to activated macrophage conditioned media. Downregulation of E-cadherin, required for maintenance of stable junction and β-catenin essential for cell-cell adhesion was noticed in response to macrophage conditioned media. Transcription factors like NFk-B, snail and slug were translocated to the nucleus, which is indicative of the initiation of EMT. Our data provides evidence that macrophage secreted proteins play a crucial role in epithelial-mesenchymal transition in thyroid tumor advancement and metastasis. We have successfully identified some significant markers including transcription factors such as NFk-B, slug, twist and snail that play a critical role in the induction of epithelial to mesenchymal transition in thyroid cancer. These findings will allow for the possible development of targeted therapy designed at inhibiting EMT and subsequent suppression of thyroid cancer metastasis and dissemination.
Citation Format: Neha Y. Tuli, Jonathan Cabin, Robert Suriano, Robert Bednarczyk, Elyse Hanly, Jan Geliebter, Edward Shin, Raj K. Tiwari. Tumor microenvironment based modulation of thyroid cancer phenotype. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1107. doi:10.1158/1538-7445.AM2014-1107