The transcribed ultraconserved regions (T-UCRs) are a family of long non-coding RNAs implicated in human carcinogenesis. The mechanism of action of T-UCRs and the factors regulating their expression in human cancers are poorly understood. In this study we show that high expression of uc.339 correlates with lower survival in 204 non-small cell lung cancer (NSCLC) patients. We also show that uc.339 found up-regulated in archival NSCLC samples, functions as a decoy for miR-339-3p, -663-3p and -95-5p. As a result, Cyclin E2, a direct target of these microRNAs is up-regulated, promoting cancer growth and migration. We provide evidence from cell lines and primary samples suggesting that TP53 directly regulates uc.339. Our results support a key role for uc.339 in lung cancer.