ASXL3 is a Novel Pluripotency Factor in Human Respiratory Epithelial Cells and a Potential Therapeutic Target in Small Cell Lung Cancer

Abstract

In this study, we generated induced pluripotent stem cells (iPSC) from normal human small airway epithelial cells (SAEC) to investigate epigenetic mechanisms of stemness and pluripotency in lung cancers. We documented key hallmarks of reprogramming in lung iPSC (Lu-iPSC) that coincided with modulation of more than 15,000 genes relative to parental SAEC. Of particular novelty, we identified the PRC2-associated protein, ASXL3 which was markedly upregulated in Lu-iPSC and small cell lung cancer (SCLC) lines and clinical specimens. ASXL3 overexpression correlated with increased genomic copy number in SCLC lines. ASXL3 silencing inhibited proliferation, clonogenicity and teratoma formation by Lu-iPSC, and diminished clonogenicity and malignant growth of SCLC cells in-vivo. Collectively, our studies validate the utility of the Lu-iPSC model for elucidating epigenetic mechanisms contributing to pulmonary carcinogenesis, and highlight ASXL3 as a novel candidate target for SCLC therapy.