Impact of heavy metal/pesticide mixtures on colorectal cell function

Abstract

Introduction: There may be a causal relationship between environmental factors and the development of colorectal cancer, but this needs further examination. Little data exists examining heavy metal or pesticide effects on colorectal cells. This study is the first to begin systematic examination of cadmium, glyphosate and cadmium-glyphosate mixtures on colorectal cell function.

Hypothesis: Normal colorectal cells exposed to cadmium, glyphosate or mixture will be more severely affected compared to colorectal tumor cells.

Design: An experimental study with controlled experiments using 2-way or a 3-way analysis of variance followed by appropriate posthoc analysis comparing treatment groups to control.

Methods: Tumor (DLD-1) and control (CCD-18Co) colorectal cells were maintained according to ATCC guidelines. Cells were plated (96-well plate) at a density of 105 cells/well and allowed to adhere 24 hours prior to assay. Assays for viability and cytotoxicity were performed according to the manufacturer's instructions.

Results: A significant interaction (cell line x treatment) was observed for viability (F5,36=33.37; p<0.0001) and cell number (F5,36=186.0; p<0.0001). Both cell lines were robustly affected by cadmium, but CCD-18Co cells were most sensitive to glyphosate. Exposure to subtoxic concentrations of cadmium or glyphosate mixtures resulted in significant reductions in CCD-18Co viability and number compared to control values.

Conclusions: Cadmium exposure exerted similar affects in each cell line, but CCD-18Co cells were more sensitive to the toxic effects of glyphosate and mixtures. Increased sensitivity may increase the susceptibility of normal cells converting to cancerous cells under prolonged exposure.