Transcriptional and posttranscriptional regulation of HOXA13 by lncRNA HOTTIP facilitates tumorigenesis and metastasis in esophageal squamous carcinoma cells

The long non-coding RNA, HOTTIP, has an important role in tumorigenesis. It is known that HOTTIP regulates HOX gene family; however, its regulatory mechanism in esophageal squamous cell carcinoma (ESCC) remains elusive. In this study, we investigated the role of HOTTIP in ESCC and observed that HOTTIP/HOXA13 was upregulated in ESCC and promoted cell proliferation and metastasis in vivo and in vitro. Interestingly, harboring a miR-30b-binding site, HOTTIP as a molecular sponge mainly regulated miR-30b level in the nucleus and modulated the repression of HOXA13 mediated by miR-30b in the cytoplasm, resulting in the positive HOTTIP/HOXA13 correlation. In addition, HOTTIP upregulated snail1 by competitively binding miR-30b, subsequently promoting epithelial-mesenchymal transition (EMT) and invasion. HOTTIP directly bound the adaptor protein WDR5 and drove histone H3 lysine 4 trimethylation and HOXA13 gene transcription in ESCC cells. In conclusion, our findings indicated that HOTTIP modulated HOXA13 at both the transcriptional and posttranscriptional levels in ESCC cells and HOTTIP-miR-30b-HOXA13 axis may serve as potential diagnostic markers or drug targets for ESCC therapies.