Overexpression of carboxylesterase contributes to the attenuation of cyanotoxin microcystin-LR toxicity

Comp Biochem Physiol C Toxicol Pharmacol. 2017 Apr:194:22-27. doi: 10.1016/j.cbpc.2017.01.008. Epub 2017 Feb 3.

Abstract

Microcystin-LR is a hepatotoxin produced by several cyanobacteria. Its toxicity is mainly due to a inhibition of protein phosphatase, PP1 and PP2A. Previously, we used a cell line stably expressing uptake transporter for microcystin-LR, OATP1B3 (HEK293-OATP1B3 cells). In this study, to determine whether overexpression of carboxylesterase (CES), which degrades ester-group and amide-group, attenuates the cytotoxicity of microcystin-LR, we generated the HEK293-OATP1B3/CES2 double-transfected cells. HEK293-OATP1B3/CES2 cells showed high hydrolysis activity of p-nitrophenyl acetate (PNPA), which is an authentic substrate for esterase. CES activity in HEK293-OATP1B3/CES2 cells was approximately 3-fold higher than that in the HEK293-OATP1B3 cells. HEK293-OATP1B3/CES2 cells (IC50: 25.4±7.7nM) showed approximately 2.1-fold resistance to microcystin-LR than HEK293-OATP1B3 cells (IC50: 12.0±1.5nM). Moreover, the CES inhibition assay and microcystin-agarose pull down assay showed the possibility of the interaction between CES2 and microcystin-LR. Our results indicated that the overexpression of CES2 attenuates the cytotoxicity of microcystin-LR via interaction with microcystin-LR.

Keywords: Carboxylesterase; Irinotecan; Microcystin-LR; OATP1B3; Overexpression.

MeSH terms

  • Absorption, Physiological / drug effects
  • Bacterial Toxins / antagonists & inhibitors
  • Bacterial Toxins / metabolism
  • Bacterial Toxins / toxicity*
  • Binding Sites
  • Carboxylesterase / antagonists & inhibitors
  • Carboxylesterase / chemistry
  • Carboxylesterase / genetics
  • Carboxylesterase / metabolism*
  • Carcinogens, Environmental / chemistry
  • Carcinogens, Environmental / metabolism
  • Carcinogens, Environmental / toxicity*
  • Cell Survival / drug effects
  • Drug Resistance
  • Enzyme Induction / drug effects
  • Enzyme Inhibitors / pharmacology
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Hep G2 Cells
  • Humans
  • Inactivation, Metabolic / drug effects
  • Marine Toxins
  • Microcystins / antagonists & inhibitors
  • Microcystins / metabolism
  • Microcystins / toxicity*
  • Nitrophenols / pharmacology
  • Organic Anion Transporters, Sodium-Independent / genetics
  • Organic Anion Transporters, Sodium-Independent / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Solute Carrier Organic Anion Transporter Family Member 1B3
  • Substrate Specificity

Substances

  • Bacterial Toxins
  • Carcinogens, Environmental
  • Enzyme Inhibitors
  • Marine Toxins
  • Microcystins
  • Nitrophenols
  • Organic Anion Transporters, Sodium-Independent
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • SLCO1B3 protein, human
  • Solute Carrier Organic Anion Transporter Family Member 1B3
  • Green Fluorescent Proteins
  • bis(4-nitrophenyl)phosphate
  • CES2 protein, human
  • Carboxylesterase
  • cyanoginosin LR