The Effects of Repeated Exposure of 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8- dimethylimidazo[4,5-f]quinoxaline (MeIQx) on Bhas 42 Cell Line at  Human Physiologically Relevant Doses 

Thayvee Geetha Bharathi Silvaragi¹, Azman Seeni¹, Siti Nazmin Saifuddin^1,* 

Abstract

Introduction: Heterocyclic amines (HCAs) are among the major groups of food carcinogens produced by high-temperature cooking of proteinaceous food. This study aims to examine the effects of two of the most abundant HCAs, 2-amino-1-methyl-6- phenylimidazo-[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline (MeIQx) on Bhas 42 cells’ viability and proliferation upon repeated  exposure at human physiologically relevant concentrations. Methods: Cytotoxicity and cell proliferation of PhIP- and MeIQx-treated Bhas 42 cells were assessed using the alamar blue assay for 48 hours and 8 days, respectively. In both assays, Bhas 42 cells were exposed to PhIP or MeIQx at concentrations of 10^-7, 10^-8, 10^-9, and 10^-10 M, respectively, which were diluted in three different vehicle concentrations of DMSO, namely 0.003%, 0.003%, and 0.1%. In the cell proliferation assay, the cells were repeatedly exposed to all sets of treatments every 48 hours for 8 days. Results: For cytotoxicity assay, all concentrations of PhIP exhibited a significant toxic effect in 0.003% and 0.03% DMSO with reductions of cell viability up to 19.1% and 75.6 %, respectively whereas MeIQx showed toxic effects only in 0.03% DMSO, specifically at the two highest doses with cell viability reduced up to 90.4% and 75.0%, respectively.  In the cell proliferation test, all concentrations of PhIP and MeIQx in all vehicle concentrations did not cause any toxic effects on Bhas 42 cells. Conclusion: The current study shows that at human physiologically relevant concentrations, the toxic effect of PhIP and MeIQx on Bhas 42 cells decreased when the cells were exposed to these carcinogens for a longer duration compared to when exposed in a short period of time regardless of DMSO concentrations. Therefore, further research on the carcinogenic potential of those HCAs may need to take these findings into account for better elucidation of their mechanism of action. 

Keywords: Cytotoxicity, Heterocyclic amines, PhIP, MeIQX, Bhas 42 cells

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