About pesticides and other demons: induction of tumor angiogenesis in our breasts

LORENA ZÁRATE; CAROLINA PONTILLO; ALEJANDRO ESPAÑOL; NOELIA MIRET; FLORENCIA CHIAPPINI; CLAUDIA COCCA; LAURA ALVAREZ; DIANA KLEIMAN DE PISAREV; MARÍA ELENA SALES; ANDREA RANDI

Mar del Plata

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica; 2018

Sociedad Argentina de Investigación Clínica

Breast cancer is the most frequent tumor in women worldwide. Pesticides that act as endocrine disruptors have been shown to affect normal mammary development. In this study, we examined the action of Hexachlorobenzene (HCB) and Chlorpyrifos (CPF) on angiogenesis in mammary carcinogenesis in vivo and in vitro. We analyzed the levels of proangiogenic factors such as vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2), as well as the expression of the nitric oxide synthases (NOS) by WB and their production of nitric oxide (NO) by Griess reagent. In a xenograft model with MCF-7 cells (+ERα), HCB (3 mg/kg b.w.) and CPF (0.1 mg/kg b.w.) enhance angiogenic switch (number of vessels/mm2) and increase VEGF expression in mice skin (p<0.05). For in vitro time-course studies, HCB (0.005 µM) at 3 h increases VEGF, COX-2 and NOS protein levels (p<0.05), while 5 µM enhances VEGF and COX-2 levels (p<0.001) at 24 h, but decreases NOS expression at different times. CPF (0.05 and 50 µM) at 6 and 24 h, increases all involved protein expression (p<0.05). Exposure to each pesticide enhances NO production (0.005 µM HCB at 3 h and 0.05 µM CPF at 3 and 6 h; p<0.05). To demonstrate that VEGF and COX-2 induction occurs through NO-dependent mechanism, we inhibited (L-NMMA) the production of NO in the presence of pesticides at low doses. We found that L-NMMA prevents the increase in VEGF and COX-2 expression in MCF-7 induced by HCB or CPF (p<0.001). The environmental doses of HCB and CPF stimulate angiogenic switch and VEGF expression in vivo. Pesticides induce VEGF, COX-2 and NOS expression in MCF-7 at similar doses that promote proliferation and angiogenesis. These alterations could contribute to the formation of preneoplastic lesions in the healthy mammary gland, as well as to the progression in human breast tumors.