Abstract 960: Blocking the Notch pathway induces mesenchymal-to-epithelial transition in lung adenocarcinoma: A novel approach to overcoming chemoresistance.
Authors: Hassan Khaled , Wang Luo , Korkaya Hasan , O'Dowd Paige , Dubaisi Sarah , Kadi Rayyan , Nasr Rawad , Zhang Binghui , Davis April , Kalemkerian Gregory , Wicha Max 
Published: August 2014

Abstract
Backgroung: The Epithelial-Mesenchymal Transition (EMT) is a key developmental program that is often activated during cancer invasion and metastasis. EMT cells possess the characteristics of cell motility, invasiveness, and have stem cells properties. EMT expression profile correlates with resistance to chemotherapy and poor outcome in multiple tumors and there is evidence suggesting an integral role of Notch pathway in mediating an EMT status. In this study, we investigated Notch activity and EMT status and the correlation with chemoressitance in lung adenocarcinoma.
Results: Transduction of multiple lung adenocarcinoma cell lines, NCI-H1299, NCI-H460, NCI-H358, NCI-H441 with a Notch GFP-reporter construct identified a subset of cells with high Notch activity (GFP-positive). We compared cell migration capacity of GFP-positive and -negative cells utilizing a transwell invasion assay. Cells with high Notch activity, as evidenced by GFP expression, had a significantly higher migration capability as compared to GFP-negative cells. To evaluate resistance to chemotherapy, we treated GFP-pos and GFP-neg cells with docetaxel or cisplatin and measured apoptosis by Annexin V expression with flow cytometry. GFP-pos cells showed major resistance to both agents as compared to GFP-neg cells. When GFP-pos cells were exposed to a Notch activity blocker, gamma secretase inhibitor (GSI), these cells were rendered sensitive to cisplatin or docetaxel exposure as evident by an increase in Annexin V expression. Using RNA microarray analysis and RT-PCR assays, there was an increased expression of EMT related genes (Vimentin, N-Cadherin, Snail-1,….) in GFP-pos cells as compared to GFP-neg cells. Furthermore, NOD/SCID mice with subcutaneous primary lung tumor xenografts treated with GSI showed decreased expression of downstream effectors of Notch as as well as vimentin. Mice treated with combination of GSI and docetaxel had better tumor control as compared to those treated with GSI and docetaxel as single agents.
Conclusion: These studies suggest that the Notch pathway is an important regulator of EMT status and that its inhibition induces mesenchymal to epithelial transition overcoming chemoresistnace. Notch inhibitors in combination with standard chemotherapy present a potential effective approach to achieve better disease control in lung cancer.
Citation Format: Khaled Hassan, Luo Wang, Hasan Korkaya, Paige O'Dowd, Sarah Dubaisi, Rayyan Kadi, Rawad Nasr, Binghui Zhang, April Davis, Gregory Kalemkerian, Max Wicha. Blocking the Notch pathway induces mesenchymal-to-epithelial transition in lung adenocarcinoma: A novel approach to overcoming chemoresistance. [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 960. doi:10.1158/1538-7445.AM2013-960