XIST Induced by JPX Suppresses Hepatocellular Carcinoma by Sponging miR-155-5p

Yonsei Med J. 2018 Sep;59(7):816-826. doi: 10.3349/ymj.2018.59.7.816.

Abstract

Purpose: The influence of X-inactive specific transcript (XIST) and X-chromosome inactivation associated long non-coding RNAs (lncRNAs) just proximal to XIST (JPX) on hepatocellular carcinoma (HCC) remains controversial in light of previous reports, which the present study aimed to verify.

Materials and methods: The DIANA lncRNA-microRNA (miRNA) interaction database was used to explore miRNA interactions with JPX or XIST. JPX, XIST, and miR-155-5p expression levels in paired HCC specimens and adjacent normal tissue were analyzed by RT-qPCR. Interaction between XIST and miR-155-5p was verified by dual luciferase reporter assay. Expression levels of miR-155-5p and its known target genes, SOX6 and PTEN, were verified by RT-qPCR and Western blot in HepG2 cells with or without XIST knock-in. The potential suppressive role of XIST and JPX on HCC was verified by cell functional assays and tumor formation assay using a xenograft model.

Results: JPX and XIST expression was significantly decreased in HCC pathologic specimens, compared to adjacent tissue, which correlated with HCC progression and increased miR-155-5p expression. Dual luciferase reporter assay revealed XIST as a direct target of miR-155-5p. XIST knock-in significantly reduced miR-155-5p expression level and increased that of SOX6 and PTEN, while significantly inhibiting HepG2 cell growth in vitro, which was partially reversed by miR-155-5p mimic transfection. JPX knock-in significantly increased XIST expression and inhibited HepG2 cell growth in vitro or tumor formation in vivo in a XIST dependent manner.

Conclusion: JPX and XIST play a suppressive role in HCC. JPX increases expression levels of XIST in HCC cells, which suppresses HCC development by sponging the cancer promoting miR-155-5p.

Keywords: JPX; X-chromosome inactivation; XIST; hepatocellular carcinoma; lncRNA; miR-155-5p.

MeSH terms

  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Cell Proliferation / genetics
  • Gene Expression Regulation, Neoplastic / genetics
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • PTEN Phosphohydrolase / genetics*
  • PTEN Phosphohydrolase / metabolism
  • RNA, Long Noncoding / metabolism*

Substances

  • MIRN155 microRNA, human
  • MicroRNAs
  • RNA, Long Noncoding
  • XIST non-coding RNA
  • PTEN Phosphohydrolase
  • PTEN protein, human