Circular RNA circPICALM sponges miR-1265 to inhibit bladder cancer metastasis and influence FAK phosphorylation

EBioMedicine. 2019 Oct:48:316-331. doi: 10.1016/j.ebiom.2019.08.074. Epub 2019 Oct 21.

Abstract

Background: Metastasis is a major obstacle in the treatment of bladder cancer (BC). Circular RNAs exert various functions in the aggressive biological behaviour of cancers. In this study, we aimed to elucidate how circPICALM influences BC metastasis.

Methods: The expression of circPICALM was analysed by real-time PCR. The tumourigenic properties of BC cells were evaluated using in vitro migration, invasion, and wound healing assays and an in vivo footpad model. The interaction between circPICALM and miR-1265 was confirmed by pull-down and dual-luciferase reporter assays and biotin-labelled miRNA capture. The interaction of STEAP4 and focal adhesion kinase (FAK) was confirmed by co-immunoprecipitation.

Findings: CircPICALM was downregulated in BC tissues, and low circPICALM expression was related to advanced T stage, high grade, lymph node positivity and poor overall survival. Overexpression of circPICALM inhibited the metastasis of BC cells, and DHX9 negatively regulated circPICALM levels. CircPICALM colocalized with miR-1265 and acted as a sponge for this miRNA, and the pro-invasion effect of miR-1265 was abolished by circPICALM overexpression. STEAP4, a target of miR-1265, suppressed metastasis; it bound to FAK to prevent autophosphorylation at Y397 and influenced EMT in BC cells.

Interpretation: CircPICALM can inhibit BC metastasis and bind to miR-1265 to block its pro-invasion activity. STEAP4 is a target of miR-1265 and is related to FAK phosphorylation and EMT. FUND: This research was supported by National Natural Science Foundation of China, No.81772728, National Natural Science Foundation of China, No.81772719, National Natural Science Foundation of China No.81572514.

Keywords: Bladder cancer; EMT; Metastasis; STEAP4; circPICALM; miR-1265.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cell Line, Tumor
  • Cell Proliferation
  • Epithelial-Mesenchymal Transition
  • Female
  • Focal Adhesion Protein-Tyrosine Kinases / metabolism*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • In Situ Hybridization, Fluorescence
  • Intracellular Signaling Peptides and Proteins / genetics*
  • Male
  • MicroRNAs / genetics*
  • Middle Aged
  • Models, Biological
  • Neoplasm Grading
  • Neoplasm Metastasis
  • Neoplasm Staging
  • Nuclear Proteins / genetics*
  • Phosphorylation
  • Proportional Hazards Models
  • RNA Interference
  • RNA, Circular*
  • Urinary Bladder Neoplasms / genetics*
  • Urinary Bladder Neoplasms / metabolism*
  • Urinary Bladder Neoplasms / mortality
  • Urinary Bladder Neoplasms / pathology

Substances

  • Intracellular Signaling Peptides and Proteins
  • MIRN1265 microRNA, human
  • MicroRNAs
  • Nuclear Proteins
  • PIMREG protein, human
  • RNA, Circular
  • Focal Adhesion Protein-Tyrosine Kinases