Nuclear lncRNA HOXD-AS1 suppresses colorectal carcinoma growth and metastasis via inhibiting HOXD3-induced integrin β3 transcriptional activating and MAPK/AKT signalling

Mol Cancer. 2019 Mar 1;18(1):31. doi: 10.1186/s12943-019-0955-9.

Abstract

Background: Long noncoding RNAs (lncRNAs) have been indicated to play critical roles in cancer development and progression. LncRNA HOXD cluster antisense RNA1 (HOXD-AS1) has recently been found to be dysregulated in several cancers. However, the expression levels, cellular localization, precise function and mechanism of HOXD-AS1 in colorectal carcinoma (CRC) are largely unknown.

Methods: Real-time PCR and in situ hybridization were used to detect the expression of HOXD-AS1 in CRC tissue samples and cell lines. Gain- and loss-of-function experiments were performed to investigate the biological roles of HOXD-AS1 in CRC cell line. RNA pull down, RNA immunoprecipitation and chromatin immunoprecipitation assays were conducted to investigate the mechanisms underlying the functions of HOXD-AS1 in CRC.

Results: We observed that HOXD-AS1 was located in the nucleus of CRC cells and that nuclear HOXD-AS1 was downregulated in most CRC specimens and cell lines. Lower levels of nuclear HOXD-AS1 expression were associated with poor outcomes of CRC patients. HOXD-AS1 downregulation enhanced proliferation and migration of CRC cells in vitro and facilitated CRC tumourigenesis and metastasis in vivo. Mechanistic investigations revealed that HOXD-AS1 could suppress HOXD3 transcription by recruiting PRC2 to induce the accumulation of the repressive marker H3K27me3 at the HOXD3 promoter. Subsequently, HOXD3, as a transcriptional activator, promoted Integrin β3 transcription, thereby activating the MAPK/AKT signalling pathways.

Conclusion: Our results reveal a previously unrecognized HOXD-AS1-HOXD3-Integrin β3 regulatory axis involving in epigenetic and transcriptional regulation constitutes to CRC carcinogenesis and progression.

Keywords: Colorectal carcinoma; HOXD-AS1; HOXD3; PRC2; lncRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Cell Movement
  • Cell Proliferation
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / mortality
  • Colorectal Neoplasms / pathology
  • Female
  • Gene Expression Regulation, Neoplastic*
  • HCT116 Cells
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Humans
  • Integrin beta3 / genetics*
  • Integrin beta3 / metabolism
  • Lymphatic Metastasis
  • Male
  • Mice
  • Middle Aged
  • Mitogen-Activated Protein Kinases / genetics*
  • Mitogen-Activated Protein Kinases / metabolism
  • Neoplasm Staging
  • Proto-Oncogene Proteins c-akt / genetics*
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Long Noncoding / antagonists & inhibitors
  • RNA, Long Noncoding / genetics*
  • RNA, Long Noncoding / metabolism
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Signal Transduction
  • Survival Analysis
  • Transcriptional Activation
  • Xenograft Model Antitumor Assays

Substances

  • Homeodomain Proteins
  • ITGB3 protein, human
  • Integrin beta3
  • RNA, Long Noncoding
  • RNA, Small Interfering
  • long non-coding RNA HOXD-AS1, human
  • HOXA4 protein, human
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinases