Tumor Initiation Capacity and Therapy Resistance Are Differential Features of EMT-Related Subpopulations in the NSCLC Cell Line A549

• DOI: 10.1016/j.neo.2018.09.008
• Publication Date: 2018-12-27T06:33:01Z
• Authors: Colin Charles Tièche; Yanyun Gao; Elias Daniel Bührer; Nina Hobi; Sabina Anna Berez...; Kurt Wyler; Laurène Froment; Stefan Weis; Ren-Wang Peng; Rémy Bruggmann; Primo Schär; Michael Alex Amrein; Sean Ralph Robert...; Patrick Dorn; Gregor Kocher; Carsten Riether; Adrian Ochsenbein; Ralph Alexander S...; Thomas Michael Marti
• Keywords: 0301 basic medicine; Original article; Epithelial-Mesenchymal Transition; Lung Neoplasms; 610 Medicine & health; Immunophenotyping; Mice; 03 medical and health sciences; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; 540 Chemistry; Animals; Humans; RC254-282; Cell Proliferation; 0303 health sciences; Gene Expression Profiling; Neoplasms. Tumors. Oncology. Including cancer and carcinogens; DNA Methylation; 3. Good health; Disease Models, Animal; Cell Transformation, Neoplastic; A549 Cells; Neoplastic Stem Cells; 570 Life sciences; biology; Transcriptome; Biomarkers; DNA Damage

Cell lines are essential tools to standardize and compare experimental findings in basic and translational cancer research. The current dogma states that cancer stem cells feature an increased tumor initiation capacity and are also chemoresistant. Here, we identified and comprehensively characterized three morphologically distinct cellular subtypes in the non-small cell lung cancer cell line A549 and challenge the current cancer stem cell dogma. Subtype-specific cellular morphology is maintained during short-term culturing, resulting in the formation of holoclonal, meroclonal, and paraclonal colonies. A549 holoclone cells were characterized by an epithelial and stem-like phenotype, paraclone cells featured a mesenchymal phenotype, whereas meroclone cells were phenotypically intermediate. Cell-surface marker expression of subpopulations changed over time, indicating an active epithelial-to-mesenchymal transition (EMT), in vitro and in vivo. EMT has been associated with the overexpression of the immunomodulators PD-L1 and PD-L2, which were 37- and 235-fold overexpressed in para- versus holoclone cells, respectively. We found that DNA methylation is involved in epigenetic regulation of marker expression. Holoclone cells were extremely sensitive to cisplatin and radiotherapy in vitro, whereas paraclone cells were highly resistant. However, inhibition of the receptor tyrosine kinase AXL, whose expression is associated with an EMT, specifically targeted the otherwise highly resistant paraclone cells. Xenograft tumor formation capacity was 24- and 269-fold higher in holo- than mero- and paraclone cells, respectively. Our results show that A549 subpopulations might serve as a unique system to explore the network of stemness, cellular plasticity, tumor initiation capacity, invasive and metastatic potential, and chemo/radiotherapy resistance.