SP1-induced HOXD-AS1 promotes malignant progression of cholangiocarcinoma by regulating miR-520c-3p/MYCN

The purpose of this article is to explore the function and mechanism of HOXD-AS1 in cholangiocarcinoma. TCGA, StarBase and JASPAR were applied to predict the differential expression and molecular mechanism. The qRT-PCR was conducted to detect molecular expression. The effect of HOXD-AS1 on tumor proliferation, metastasis and stemness was measured through corresponding experiments. ChIP, luciferase reporter and RIP assays were implemented to explore the regulatory mechanism of HOXD-AS1 in CCA. In this study, HOXD-AS1 expression was significantly upregulated in CCA tissues and cells compared with control groups, respectively. Increased HOXD-AS1 was markedly correlated with lymph node invasion, advanced TNM stage and poor survival of CCA patients. Moreover, HOXD-AS1 was confirmed to be an unfavorable independent prognostic factor for CCA patients. Functionally, gain- and loss-of-function experiments demonstrated that HOXD-AS1 facilitated tumor proliferation, migration, invasion, EMT, stemness and drug resistance in vitro and in vivo. For the mechanism, transcription factor SP1-induced HOXD-AS1 upregulated oncogene MYCN through competitively binding to miR-520c-3p. Furthermore, HOXD-AS1-induced malignant phenotypes were rescued by interfering miR-520c-3p and MYCN, respectively. SP1/HOXD-AS1/miR-520c-3p/MYCN plays a vital role in initiation and progression of CCA, and HOXD-AS1 is expected to be an efficient biomarker and therapeutic target.