New Generation of Cancer Stem Cells Inhibitors in Non-Small Cell Lung Cancer.

e20545 Background: Lung cancer is the commonest tumor worldwide of which the most frequent type is non-small cell lung cancer (NSCLC) that represents a large proportion of cancer deaths and is characterized by low response treatment rates and poor overall prognosis. Cancer Stem Cells (CSCs) model proposes that drug resistance, tumor progression, metastasis and recurrence might be driven by this subset of cells, with increased expression of stemness-associated markers and the ability to self-renew and differentiate. Methods: Drug screening was performed by comparing tumorspheres and monolayer cells from 4 resected NSCLC patients and 12 NSCLC cell lines, which were plated at the desired density in 200 μl of medium in 96-well plates. High-throughput screening was performed with two chemical libraries (Prestwick and Myria). Experiments were done in triplicate. Cell viability was measured after 48 h (MTS Assay) and was normalized to the respective mock-treated control cells. Based on this study 3 novel compounds were identified, namely A, B and C. Statistical analyses were considered significant at p < 0.05. EC50 was calculated with GraphPad. Relative gene expression analysis was run by RT-qPCR in the tumorspheres treated with the three compounds. Results: CSC-markers, pluripotency genes and signaling pathways were characterized from the resected NSCLC patients’ tumor-tissue and cell lines-like tumor spheres to use them as an in vitro drug screening platform. The screening assay showed selective reduced cellular viability specifically in lung tumorspheres when the three chemically-related compounds were tested (p < 0.05). This anti-proliferative effect correlated with an earlier decrease in the expression of the CSC markers critical in lung tumorspheres, such as ALDH1A1, KLF4 and SOX2. Conclusions: These compounds could be a serious promising targeted therapy for lung CSCs as major CSC-markers inhibitors, including pluripotency genes and signaling pathways. Our findings suggest that these compounds can inhibit CSCs-like properties, as evidenced by the lung sphere assays and reveal a potential use for developing novel therapeutic approaches. Supported by grants CIBERONC, PI12-02838, PI15-00753 from ISCIII, Arnal Planelles Foundation.