Upregulation of miR-21 and pro-inflammatory cytokine genes IL-6 and TNF-α in promoting a pro-tumorigenic microenvironment in canine mammary carcinomas

Res Vet Sci. 2023 Nov:164:105014. doi: 10.1016/j.rvsc.2023.105014. Epub 2023 Sep 18.

Abstract

This study evaluated the gene expression of the pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in canine mammary tumors (CMTs), and correlated them with gene expression of miRNAs expected to regulate the secretion of pro-inflammatory cytokines within the tumor microenvironment (TME). Furthermore, gene expression of cytokines and miRNAs involved in tumor cell proliferation and invasion (i.e. miR-21; miR-124; miR-145) were correlated with tumor proliferation index (Ki67 index) to determine the prognostic value in CMTs. Twenty-six canine mammary samples were used, including 22 CMTs and 4 control samples. MiR-21, IL-6 and TNF-α were upregulated in mammary carcinomas compared with controls (p < 0.05). MiR-146b was downregulated in CMTs compared with control cases (p < 0.05). IL-6 expression showed a significant positive correlation with miR-21 and a negative correlation with miR-146b; while, TNF-α gene expression was positively correlated with miR-21 and miR-145 in mammary carcinomas. In carcinomas, the Ki67 index correlated positively with gene expression of IL-6 and miR-21 and negatively correlated with miR-145 and miR-146b. Specifically, gene expression of IL-6 and miR-21 was positively correlated with ki67 index >33.3%, whereas, expression of miR-145 and miR-146b was negatively correlated with ki67 index <33.3%. Results reinforce the concept of interaction between tumor cells and inflammatory cells within the TME, with a central role of IL-6 and TNF-α. Since the upregulation of miR-21 reflects the gene overexpression of interleukins and the high proliferation index of tumor cells, this miRNA may be considered a biomarker with prognostic value in CMTs.

Keywords: Cancer-associated inflammation; Canine mammary tumors; IL-6; TNF-α; miR-146b; miR-21.

MeSH terms

  • Animals
  • Carcinoma* / veterinary
  • Cytokines / metabolism
  • Dog Diseases* / genetics
  • Dogs
  • Interleukin-6 / genetics
  • Ki-67 Antigen / genetics
  • Ki-67 Antigen / metabolism
  • MicroRNAs* / genetics
  • MicroRNAs* / metabolism
  • Tumor Microenvironment / genetics
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism
  • Up-Regulation

Substances

  • Interleukin-6
  • Tumor Necrosis Factor-alpha
  • Ki-67 Antigen
  • MicroRNAs
  • Cytokines