Transcriptomic implications of low herbicide concentrations in hepatic cells: Insights into the individual and combined effects of 2,4-D, glyphosate, and AMPA

Abstract

Glyphosate and 2,4-D are among the most widely used herbicides globally, leading to environmental presence, food contamination, and human contact. Investigations based on current toxicological limits or populational-based herbicide exposures are warranted, and in vitro bioassays provide useful tools for toxicological screening. Thus, this study evaluated the transcriptomic implications of non-cytotoxic exposures to glyphosate, its metabolite aminomethylphosphonic acid (AMPA), or 2,4-D - or to their mixes - on hepatic cells. The half maximal effective concentration (IC50) of each herbicide was calculated (cell viability) in human hepatic C3A cells and 1000-fold lower concentrations were used for transcriptomic analysis (RNA-Seq) after 48 h exposure, resembling current toxicological limits and considering herbicide water levels (glyphosate: 0.95 µg/mL; AMPA: 3.7 µg/mL; 2,4-D: 0.56 µg/mL). Glyphosate exposure enriched MAPK-related biological processes (upregulated TNF, FOS, IGF1, and PDGFB), and downregulated genes associated with lipid metabolism (CD36 and PPARA). Many AMPA exposure-related differentially expressed genes (DEGs, such as PFKFB3, HK2, and ALDOA) were associated with glucose metabolic pathways. Glyphosate and its metabolite yielded a common molecular signature, as illustrated by principal component analysis and the function of 212 shared DEGs. The exposure to 2,4-D was associated with the JNK cascade and the solute carrier family annotations. The herbicide mixtures had a discrete effect on enhancing the impact of individual herbicides, although important epithelial-mesenchymal transition genes were exclusively modified by the mixes (COL11A2, LOXL3, SNAI1). Altogether, our data reveals new perspectives on the short-term molecular effects of herbicide exposure in liver cells, emphasizing potential avenues for further exploration.