title: Chlorpyrifos promotes colorectal adenocarcinoma H508 cell growth through the activation of EGFR/ERK1/2 signaling pathway but not cholinergic pathway.
abstract: Aside from the effects on neuronal cholinergic system, epidemiological studies suggest an association between chlorpyrifos (CPF) exposure and cancer risk. This in vitro study examined the effects of CPF and its toxic metabolite, chlorpyrifos oxon (CPF-O), on the growth of human colorectal adenocarcinoma H508, colorectal adenocarcinoma HT-29, normal colon epithelial CCD841, liver hepatocellular carcinoma HepG2, and normal liver hepatocyte THLE-3 cells. The results showed that CPF (5-100 μM) concentration-dependently increased viability of H508 and CCD841 cells in serum-free conditions. This increasing trend was not found in HT-29, HepG2 and THLE-3 cells. In contrast, CPF-O (50-100 μM) reduced the viability of all cell lines. Cell cycle analysis showed the induction of cells in the S phase, and EdU incorporation assay revealed the induction of DNA synthesis in CPF-treated H508 cells indicating that CPF promotes cell cycle progression. Despite the observation of acetylcholinesterase activity inhibition and reactive oxygen species (ROS) generation, atropine (a non-selective muscarinic acetylcholine receptor antagonist) and N-acetylcysteine (a potent antioxidant) failed to inhibit the growth-promoting effect of CPF. CPF increased the phosphorylation of epidermal growth factor receptor (EGFR) and its downstream effector, extracellular signal regulated kinase (ERK1/2), in H508 cells. AG-1478 (a specific EGFR tyrosine kinase inhibitor) and U0126 (a specific MEK inhibitor) completely mitigated the growth promoting effect of CPF. Altogether, these results suggest that EGFR/ERK1/2 signaling pathway but not cholinergic pathway involves in CPF-induced colorectal adenocarcinoma H508 cell growth.
authors.affiliation: Laboratory of Pharmacology, Chulabhorn Research Institute, Bangkok 10210, Thailand.
authors.forename: Tawit
authors.initials: T
authors.lastname: Suriyo
authors.affiliation: Environmental Toxicology Program, Chulabhorn Graduate Institute, Bangkok 10210, Thailand.
authors.forename: Phum
authors.initials: P
authors.lastname: Tachachartvanich
authors.affiliation: Laboratory of Pharmacology, Chulabhorn Research Institute, Bangkok 10210, Thailand.
authors.forename: Daranee
authors.initials: D
authors.lastname: Visitnonthachai
authors.affiliation: Laboratory of Pharmacology, Chulabhorn Research Institute, Bangkok 10210, Thailand; Environmental Toxicology Program, Chulabhorn Graduate Institute, Bangkok 10210, Thailand.
authors.forename: Piyajit
authors.initials: P
authors.lastname: Watcharasit
authors.affiliation: Laboratory of Pharmacology, Chulabhorn Research Institute, Bangkok 10210, Thailand; Environmental Toxicology Program, Chulabhorn Graduate Institute, Bangkok 10210, Thailand; Center of Excellence on Environmental Health and Toxicology, Office of Higher Education Commission, Ministry of Education, Bangkok 10400, Thailand. Electronic address: jutamaad@cri.or.th.
authors.forename: Jutamaad
authors.initials: J
authors.lastname: Satayavivad
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology; D000975:Antioxidants / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000633:toxicity; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D058851:GPI-Linked Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D019073:HT29 Cells; D056945:Hep G2 Cells; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010575:Pesticides / Q000633:toxicity*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000975:Antioxidants; D058851:GPI-Linked Proteins; D018727:Muscarinic Antagonists; D010575:Pesticides; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; C009618:O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; C512478:EGFR protein, human; D066246:ErbB Receptors; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C548244:ACHE protein, human; D000110:Acetylcholinesterase; D004390:Chlorpyrifos
keywords: Cell growth EGFR; Chlorpyrifos; Chlorpyrifos oxon; Colorectal cancer; H508 cells; Insecticides