Glyphosate influences cell proliferation in vitro

Abstract

Glyphosate is the most widely used herbicide worldwide. However, since the International Agency for Research on Cancer (IARC) classified glyphosate as a Class 2A ‘probable carcinogen’ to humans, the safety of this synthetic chemical has been under debate and requires validation. Most studies on glyphosate have been conducted in animals, and the effects of glyphosate in humans are not fully understood. In the present study, we report that glyphosate increases the rate of cell growth in human embryonic kidney 293 (HEK293) cells. Interestingly, the concentrations of glyphosate ranging between 0.6 and 18 µM enhance cell proliferation, while lower or higher concentrations do not stimulate cell growth or interfere with it, respectively. At the molecular level, cell biology and biochemical data demonstrate that glyphosate promotes the transcription of EGR1, JUN, FOS, and MYC, which are critical transcription factors and immediate early genes for cell cycle progression, and cell cycle regulators including cyclin B1, cyclin D1, and p21. NEAT1, a long non-coding RNAs that is implicated in cancers and active gene transcription are increased in glyphosate-treated cells. In addition, the absorption efficiency of glyphosate to HEK293 cells estimates approximately 11 pM/cell/day, and glyphosate metabolism appears increased when incubated with HEK293 cells. Our findings provide valuable evidence on the effects of glyphosate on human cell growth and suggest that glyphosate promotes cell proliferation by activating gene expression of cell cycle regulators in humans in vitro. Abbreviations: IARC: International Agency for Research on Cancer; EPSPS: 5-enolpyruvylshikimate-3-phosphate synthase; AMPA: aminomethylphosphonic acid; WHO: World Health Organization; EFSA: European Food Safety Authority; RT-qPCR: reverse transcription quantifying PCR; lncRNA: Long non-coding RNA; NEAT1: Nuclear paraspeckle assembly transcript 1; WST: water-soluble tetrazolium salt; ChIP-PCR: chromatin immunoprecipitation-polymerase chain reaction; CDKs: cyclin-dependent protein kinases; MALAT1: metastasis-associated lung adenocarcinoma transcription 1; LC-MS-MS: liquid chromatography-tandem mass spectrometry.