Cholpraipimolrat Wanida, Suriyo Tawit, Rangkadilok Nuchanart, Nookabkaew Sumontha, Satayavivad Jutamaad
Environmental Toxicology Program, Chulabhorn Graduate Institute (CGI), Chulabhorn Royal Academy, Kamphaeng Phet 6, Laksi, Bangkok 10210, Thailand.
Laboratory of Pharmacology, Chulabhorn Research Institute (CRI), Kamphaeng Phet 6, Laksi, Bangkok 10210, Thailand; Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok 10400, Thailand.
Food Chem Toxicol. 2017 Dec;110:33-41. doi: 10.1016/j.fct.2017.09.052. Epub 2017 Sep 30.
Hijiki seaweed (Hijikia fusiformes) contains high levels of inorganic arsenic, a known carcinogen. However, scientific reports on carcinogenic risks associated with the consumption of this seaweed are limited. This study investigated the effects of seaweed extracts contaminated with arsenic on two colorectal cancer cell lines. Two seaweed extracts, including Hijiki and red seaweed, induced H508 but not HT29 cell proliferation. Growth induction of H508 cells after treatments with Hijiki and sodium arsenite at concentrations equivalent to arsenic found in Hijiki was observed by both MTT and BrdU assays. Hijiki and sodium arsenite induced epidermal growth factor receptor (EGFR) and ERK1/2 activations. AG1478, an EGFR inhibitor, decreased the activation of EGFR and ERK1/2 induced by Hijiki and sodium arsenite. U0126, an ERK1/2 upstream inhibitor, and atropine, a muscarinic acetylcholine receptor (mAChR) antagonist, but not AG1478 completely inhibited the proliferative effect of Hijiki. Altogether, the results suggest that the presence of arsenic in seaweed may partly contribute to the proliferation of colorectal cancer cells. EGFR-dependent, and -independent ERK1/2 signaling pathways, and mAChR may be involved in the growth stimulation by Hijiki. These results raise concern regarding the potential colorectal cancer risks from regular consumption of Hijiki containing high contents of inorganic arsenic.
