Pomegranate polyphenolics suppressed azoxymethane-induced colorectal aberrant crypt foci and inflammation: possible role of miR-126/VCAM-1 and miR-126/PI3K/AKT/mTOR

Carcinogenesis. 2013 Dec;34(12):2814-22. doi: 10.1093/carcin/bgt295. Epub 2013 Aug 29.

Abstract

The antitumorigenic activities of polyphenols such as ellagitannins and anthocyanins in pomegranate (Punica granatum L.) have been previously studied where cytotoxic, anti-inflammatory and antioxidant effects were evident in various cancer models. The objective of this study was to investigate the role of miR-126/vascular cell adhesion molecule 1 (VCAM-1) and miR-126/phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) in pomegranate-mediated anti-inflammatory and anticarcinogenic effects in vivo and in vitro. Sprague-Dawley rats (n = 10 per group) received pomegranate juice (2504.74 mg gallic acid equivalents/l) or a polyphenol-free control beverage ad libitum for 10 weeks and were injected with azoxymethane (AOM) subcutaneously (15mg/kg) at weeks 2 and 3. Consumption of pomegranate juice suppressed the number of aberrant crypt foci (ACF) and dysplastic ACF by 29 and 53.5% (P = 0.05 and 0.04), respectively, and significantly lowered proliferation of mucosa cells. Pomegranate juice significantly downregulated proinflammatory enzymes nitric oxide synthase and cyclooxygenase-2 messenger RNA (mRNA) and protein expression. In addition, it suppressed nuclear factor-κB and VCAM-1 mRNA and protein expression in AOM-treated rats. Pomegranate also inhibited phosphorylation of PI3K/AKT and mTOR expression and increased the expression of miR-126. The specific target and functions of miR-126 were investigated in HT-29 colon cancer cell lines. In vitro, the involvement of miR-126 was confirmed using the antagomiR for miR-126, where pomegranate reversed the effects of the antagomiR on the expression of miR-126, VCAM-1 and PI3K p85β. In summary, therapeutic potentials of pomegranate in colon tumorigenesis were due in part to targeting miR-126-regulated pathways, which contributes in the underlying anti-inflammatory mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aberrant Crypt Foci / chemically induced
  • Aberrant Crypt Foci / drug therapy*
  • Aberrant Crypt Foci / genetics
  • Aberrant Crypt Foci / metabolism
  • Animals
  • Anticarcinogenic Agents / pharmacology
  • Azoxymethane / adverse effects
  • Beverages
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Colorectal Neoplasms / chemically induced
  • Colorectal Neoplasms / diet therapy
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / metabolism
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism
  • HT29 Cells
  • Humans
  • Inflammation / chemically induced
  • Inflammation / drug therapy
  • Inflammation / genetics
  • Inflammation / metabolism
  • Lythraceae
  • Male
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism
  • Phosphatidylinositol 3-Kinase / genetics*
  • Phosphatidylinositol 3-Kinase / metabolism
  • Polyphenols / pharmacology*
  • Proto-Oncogene Proteins c-akt / genetics*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • TOR Serine-Threonine Kinases / genetics*
  • TOR Serine-Threonine Kinases / metabolism
  • Vascular Cell Adhesion Molecule-1 / genetics*
  • Vascular Cell Adhesion Molecule-1 / metabolism

Substances

  • Anticarcinogenic Agents
  • MicroRNAs
  • Polyphenols
  • Vascular Cell Adhesion Molecule-1
  • Nitric Oxide Synthase Type II
  • Cyclooxygenase 2
  • Phosphatidylinositol 3-Kinase
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Azoxymethane