Effects of chlorpyrifos on growth of estrogen-dependent human breast cancer cell line

CLARA VENTURA; MARIEL NUÑEZ; VIRGINIA GAIDO; D MARTINEL LAMAS; ANDREA RANDI; ANDRES VENTURINO; ELENA RIVERA; CLAUDIA COCCA

Paris

Congreso; 47th Congress of the European Societies of Toxicology EUROTOX 2011; 2011

Sociedades Europeas de Toxicologia

It has been reported that environmental chemicals are involved in breast cancer risk. Chlorpyrifos (CPF) is an organophosphorus insecticide, commonly applied for pest control in fruit producing regions of our country. It was also described as endocrine disruptor affecting estrogen responses. Our objective was to evaluate the effect of CPF on estrogen dependent MCF-7 breast cancer cells.  CPF was tested in vitro at 5.10-2; 0.5; 5 and 50 µM. Citotoxicity was studied by MTT assay and proliferation by clonogenic assay and bromodeoxyuridine (BrdU) incorporation. Cell cycle progression was studied by flow cytometry. Western blots were performed for estrogen receptor alpha (ERá) phosphorilation and Proliferating Cell Nuclear Antigen (PCNA) and p27 expression.  Reactive oxygen species (ROS) were determined using DCF fluorescent staining and flow citometry. Results obtained show that CPF at 50 µM induced a non-significant decrease in cell viability and a diminished clonogenic proliferation (41 %; p<0.01). This effect was associated with an increase in ROS content (32 %; p<0.001) and a cell increment in phase sub-G0 (23%; p<0.001).  Conversely, CPF at 5.10 -2 µM induced an increase in BrdU incorporation (38%; p<0.05) and it was related to a decrease in p27 expression. PCNA (30%; p <0.05) and ERá phosphorilation (36%; p<0.01) levels were increased. We conclude that high doses of xenobiotics inhibit cell proliferation and our results were not unexpected at those concentrations. However, low levels of CPF significantly induced proliferation in MCF-7 cells and it seems to be related to estrogen dependence of the cells.