Calreticulin regulates vascular endothelial growth factor-A mRNA stability in gastric cancer cells

PLoS One. 2019 Nov 14;14(11):e0225107. doi: 10.1371/journal.pone.0225107. eCollection 2019.

Abstract

Calreticulin (CRT) and vascular endothelial growth factor-A (VEGF-A) are crucial for angiogenesis, and mediate multiple malignant behaviors in gastric cancer. In this study, we report that CRT is positively correlated with VEGF-A in gastric cancer patients. Moreover, high expressions of both CRT and VEGF-A are markedly associated with the pathological stage, progression, and poor prognosis in the patients. Therefore, we sought to elucidate the mechanism by which CRT affects VEGF-A in gastric cancer. Firstly, we demonstrate the novel finding that knockdown of CRT reduced VEGF-A mRNA stability in two gastric cancer cell lines, AGS and MKN45. The AU-Rich element (ARE) is believed to play a crucial role in the maintenance of VEGF-A mRNA stability. Luciferase reporter assay shows that knockdown of CRT significantly decreased the activity of renilla luciferase with VEGF-A ARE sequence. Additionally, competition results from RNA-binding/electrophoretic mobility shift assay indicate that CRT forms an RNA-protein complex with the VEGF-A mRNA by binding to the ARE. In addition, the proliferation rate of human umbilical vein endothelial cells (HUVEC) was significantly reduced when treated with conditioned medium from CRT knockdown cells; this was rescued by exogenous VEGF-A recombinant protein. Our results demonstrate that CRT is involved in VEGF-A ARE binding protein complexes to stabilize VEGF-A mRNA, thereby promoting the angiogenesis, and progression of gastric cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor
  • Calreticulin / metabolism*
  • Cell Line, Tumor
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Metastasis
  • Neoplasm Staging
  • Protein Binding
  • RNA Stability*
  • RNA, Messenger* / genetics
  • Stomach Neoplasms / genetics*
  • Stomach Neoplasms / metabolism*
  • Stomach Neoplasms / mortality
  • Stomach Neoplasms / pathology
  • Vascular Endothelial Growth Factor A / genetics*

Substances

  • Biomarkers, Tumor
  • CALR protein, human
  • Calreticulin
  • RNA, Messenger
  • Vascular Endothelial Growth Factor A

Grants and funding

This work was supported by Ministry of Science and Technology, Taiwan, MOST 106-2314-B-002-216-MY3, to Chiung-Nien Chen, https://www.most.gov.tw/?l=en. CN Chen provided clinical samples and conceived the project; Ministry of Science and Technology, Taiwan, MOST 106-2314-B-002-193- and 107-2314-B-002-161- to Wen-Chin Weng, https://www.most.gov.tw/?l=en. WC Weng contributed to conception of the project.