An integrative transcriptome analysis reveals a functional role for thyroid transcription factor-1 in small cell lung cancer.

Small cell lung cancer (SCLC) is a neuroendocrine tumour that exhibits rapid growth and metastatic spread. Although SCLC represents a prototypically undifferentiated cancer type, thyroid transcription factor-1 (TTF-1, gene symbol NKX2-1), a master regulator for pulmonary epithelial cell differentiation and lung morphogenesis, is strongly upregulated in this aggressive cancer type. The aim of this study was to evaluate a functional role for TTF-1 in SCLC. We demonstrated that achaete-scute complex homolog 1 (ASCL1), an essential transcription factor for neuroendocrine differentiation, positively regulated TTF-1 in SCLC cell lines. Subsequently, we described genes and microRNAs (miRNAs) that were possibly controlled by TTF-1 and identified nuclear factor IB (NFIB), a recently characterised driver of SCLC progression, as a transcriptional target of TTF-1. Our findings shine light on a regulatory axis in SCLC consisting of ASCL1/TTF-1/NFIB that potentially contributes to the tumourigenesis of SCLC.