CCL2/CCR2 axis induces hepatocellular carcinoma invasion and epithelial-mesenchymal transition in vitro through activation of the Hedgehog pathway

Oncol Rep. 2018 Jan;39(1):21-30. doi: 10.3892/or.2017.6069. Epub 2017 Nov 2.

Abstract

Chemokine (C-C motif) ligand 2 (CCL2) has been shown to play an important role in the regulation of tumor cell growth, metastasis and host immune response. CCL2 preferentially binds to the C-C chemokine receptor type 2 (CCR2), which is expressed in various tissues. However, the role of the CCL2/CCR2 axis in hepatocellular carcinoma (HCC) invasion and its molecular mechanisms remain unclear. The aim of this study was to elucidate this issue. The human HCC cell line MHCC-97H was treated with CCL2. Cyclopamine, a smoothened (SMO) antagonist, was used to inhibit SMO activity. CCR2 siRNA and Gli-1 siRNA were used to inhibit CCR2 and Gli-1 expression respectively. The effect of CCL2 and Hedgehog (Hh) signaling on cancer cell epithelial-mesenchymal transition (EMT) and invasion was evaluated by quantitative real‑time PCR analysis, western blotting and Transwell invasion assay. Our results revealed that CCL2 induced HCC cell invasion and EMT. This effect was accompanied by the activation of Hh signaling, the upregulation of Snail and vimentin and the reduction of E-cadherin. Notably, prior silencing of CCR2 with siRNA abolished CCL2-induced Hh signaling activation, Snail and vimentin upregulation, E-cadherin reduction, as well as HCC cell invasion and EMT. Furthermore, pretreatment with cyclopamine or predepletion of Gli-1 by siRNA also eliminated the changes of Snail, vimentin and E-cadherin, and HCC invasion and EMT caused by CCL2. Collectively, our results revealed that the link between the CCL2/CCR2 axis and the Hh pathway plays an important role in HCC progression. Therefore, the CCL2/CCR2 axis may represent a promising therapeutic target to prevent HCC progression.

MeSH terms

  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism*
  • Cell Line, Tumor
  • Cell Movement
  • Chemokine CCL2 / genetics
  • Chemokine CCL2 / metabolism*
  • Epithelial-Mesenchymal Transition
  • Gene Expression Regulation, Neoplastic
  • Gene Knockdown Techniques
  • Hedgehog Proteins / metabolism
  • Humans
  • In Vitro Techniques
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism*
  • Neoplasm Invasiveness
  • Receptors, CCR2 / genetics
  • Receptors, CCR2 / metabolism*
  • Signal Transduction*
  • Smoothened Receptor / genetics
  • Smoothened Receptor / metabolism
  • Zinc Finger Protein GLI1 / genetics
  • Zinc Finger Protein GLI1 / metabolism

Substances

  • CCL2 protein, human
  • CCR2 protein, human
  • Chemokine CCL2
  • GLI1 protein, human
  • Hedgehog Proteins
  • Receptors, CCR2
  • SMO protein, human
  • Smoothened Receptor
  • Zinc Finger Protein GLI1