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How Roundup Weedkiller Can Promote Cancer, New Study Reveals
by Sayer Ji
Green Med Info, 11 November 2013
Roundup herbicide (glyphosate) is in our air, rain, groundwater, soil and most food in the U.S., and an increasing body of research reveals it has cancer-promoting properties.
Researchers from the Indian Institute of Toxicology Research have recently confirmed the carcinogenic potential of Roundup herbicide using human skin cells (HaCaT ) exposed to extremely low concentrations of the world's best selling herbicide.
The researchers previously reported on glyphosate's tumor promoting potential in a two-stage mouse skin carcinogenesis model[i] through its disruption of proteins that regulate calcium (Ca2+- ) signaling and oxidative stress (SOD 1), but were unable in these investigations to identify the exact molecular mechanisms behind how glyphosate contributes to tumor promotion.
The new study, published in the peer-reviewed journal ISRN Dermatology,[ii] sought out to clarify the exact mode of tumorigenic action, finding the likely mechanism behind glyphosate's cancer promoting properties is through the downregulation of mitochondrial apoptotic (self-destructive) signaling pathways, as well as through the disruption of a wide range of cell signaling and regulatory components. Cell proliferative effects were induced by concentrations lower than .1 mM, and as low as 0.01 mM, which is four orders of magnitude lower than concentrations commonly used in GM agricultural applications (e.g. 50 mM). The fact that lower concentrations were more effective at inducing proliferation than higher concentrations (which suppressed cell growth), indicates that Roundup is a potent endocrine disrupter, and further highlights why conventional toxicological risk assessments are inadequate because they do not account for the fact that as concentrations arereduced certain types of toxicity -- e.g. endocrine disruption -- actually increase.
The researchers used the product Roundup Original (glyphosate 41%, polyethoxethyleneamine (POEA) ≅15%—Monsanto Company, St. Louis, MO, USA), and observed the following changes to human skin cells induced through exposure to this chemical mixture:
- Significant increases in cell proliferation (via disruption of CA2+ levels, i.e. decreased levels)
- Increases oxidative stress, as measured by levels of ROS (reactive oxygen species)
- Cell-cycle dysregulation, marked by an accumulation of cells in S-phase (hallmark feature of cancer)
- Increased proliferating cell nuclear antigen (PCNA), a marker for increased cell proliferation
- Increased Bromodeoxyuridin (BrdU), a marker for increased cell proliferation
- Decreases in the level of the protein IP3R1, an indication of resistance to cell death
- Increases in Bcl-2 protein, a tumor promoter gene product
- Decreases in Bax proteins, a tumor suppressor gene product
- Caspase suppression (associated with prevention of cell death)
- Changes in the expression of the Ca2+- binding family of proteins (S100 family) S100A6/S100A9, associated with various cancers.
It is important to emphasize that while the researchers observed cell proliferation-associated changes in the expression of the Ca2+- binding proteins S100A6/A9 following glyphosate exposure to human skin cells, the implications of these findings reach beyond the skin cell lineage. They explained that related modifications of the expression pattern of S100A6/A9 protein have also been found in "hepatocellular carcinoma , lung cancer , colorectal cancer , and melanoma ."
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