Abstract
The function of most long noncoding RNAs (lncRNAs) is unknown. However, recent studies reveal important roles of lncRNAs in regulating cancer-related pathways. Human antisense lncRNA-NKX2-1-AS1 partially overlaps the NKX2-1/TTF1 gene within chromosomal region 14q13.3. Amplification of this region and/or differential expression of genes therein are associated with cancer progression. Herein we show higher levels of NKX2-AS1 and NKX2-1 in lung adenocarcinomas relative to non-tumor controls but no correlation between NKX2-1-AS1 and NKX2-1 levels across specimens, or with amplification of the 14q13.3 region, suggesting that NKX2-1-AS1 and NKX2-1 are independently regulated. Loss-and-gain of function experiments showed that NKX2-1-AS1 does not regulate NKX2-1 expression, or nearby genes, but controls genes in trans. Genes up-regulated by NKX2-1-AS1-knockdown belong to cell adhesion and PD-L1/PD-1 checkpoint pathways. NKX2-1-AS1 negatively regulates endogenous CD274/PD-L1, a known target of NKX2-1, and the transcriptional activity of -1kb-CD274 promoter-reporter construct. Furthermore, NKX2-1-AS1 interferes with NKX2-1 protein binding to the CD274-promoter, likely by NKX2-1 protein-NKX2-1-AS1 interactions. Finally, NKX2-1-AS1 negatively regulates cell migration and wound healing, but not proliferation or apoptosis. These findings support potential roles of NKX2-1-AS1 in limiting motility and immune system evasion of lung carcinoma cells, highlighting a novel mechanism that may influence tumorigenic capabilities of lung epithelial cells.