Lectin from Agaricus bisporus inhibited S phase cell population and Akt phosphorylation in human RPE cells

Invest Ophthalmol Vis Sci. 2012 Nov 5;53(12):7469-75. doi: 10.1167/iovs.12-10589.

Abstract

Purpose: Lectin from the edible mushroom Agaricus bisporus (ABL) was found to inhibit cell proliferation of some ocular and cancer cell lines. To elucidate how ABL inhibited RPE cell proliferation, we investigated the changes in cell cycle distribution and cell proliferation-related signaling pathways after ABL treatment.

Methods: Primary human RPE cells were isolated and grown in DMEM/F12 with or without the ABL (20 or 90 μg/mL) for 3 days. Analysis of cell cycle was performed by flow cytometry. Phosphorylation status of Erk, Jnk, p38, and Akt as well as p53 expression levels were investigated by Western blotting. The role of phosphorylated-Akt in RPE cell proliferation was further evaluated using LY294002.

Results: After ABL treatment (90 μg/mL), the amount of cells present in the S phase was found to be reduced. These changes were not apparent in cells treated with 20 μg/mL ABL. In addition, Erk and Akt were found to be hyperphosphorylated and hypophosphorylated, respectively. The expression levels of phosphorylated-Jnk, phosphorylated-p38, and p53 were not altered when compared with those of the control cells. When RPE cells were treated with LY294002 and deprived from phosphorylated-Akt expression, cell proliferation rate was reduced. Reduction in the amount of cells present in S phase was also observed.

Conclusions: Our results showed that ABL hypophosphorylated Akt and this observation is in line with the fact that ABL attenuates cell proliferation. As the level of p53 was not significantly altered by ABL, this indicated that ABL-arrested cell cycle progression was independent of p53 activation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agaricus / metabolism*
  • Blotting, Western
  • Cell Division
  • Cell Proliferation
  • Cell Survival
  • Cells, Cultured
  • Flow Cytometry
  • Humans
  • Lectins / metabolism
  • Lectins / pharmacology*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Retinal Pigment Epithelium / cytology
  • Retinal Pigment Epithelium / drug effects
  • Retinal Pigment Epithelium / metabolism*
  • S Phase / drug effects*
  • Signal Transduction / drug effects

Substances

  • Lectins
  • Proto-Oncogene Proteins c-akt