Pesticides exposure enhances HIF-1α, VEGF and NOS-2 expression in MDA-MB-231 human breast cancer cells

Carolina Pontillo¹, Noelia V Miret¹, Alejandro Español², Lorena V Zárate¹, Florencia Chiappini¹, María Elena Sales², Diana Kleiman de Pisarev¹, Claudia Cocca³, Andrea Randi¹

Angiogenesis plays a role in local tumor growth and metastasis. Elevated levels of Hypoxia Inducible Factor-1α (HIF-1α) correlate with angiogenesis. HIF-1α induces gene expression like Cyclooxygenase-2 (COX-2), Nitric Oxide Synthase-2 (NOS-2) and Vascular Endothelial Growth Factor (VEGF). COX-2 and NOS-2 promote tumor angiogenesis. VEGF increases endothelial cells proliferation, survival and migration. Endocrine disruptors Hexachlorobenzene (HCB) and Chlorpyrifos (CPF) induce cell proliferation and tumor growth in breast cancer animal models. Our aim was to examine their action on breast cancer angiogenesis. We studied HCB (0.005, 0.05, 0.5 and 5 µM) or CPF (0.05, 0.5, 5 and 50 µM) effect in MDA-MB 231 triple negative breast cancer cells on: HIF-1α, COX-2 and NOS-2 protein levels, VEGF expression and secretion (Western Blot). Our results showed that exposure to 6 h of HCB enhances HIF-1α levels at 0.05, 0.5 and 5 µM, and NOS-2 expression and VEGF secretion at all assayed doses. In addition, at 24 h HCB (0.05 and 5 µM) increases COX-2 levels (p<0.05). Moreover, CPF for 6 h enhances HIF-1α and NOS-2 expression at all assayed doses, as well as VEGF secretion at 0.05, 0.5 and 5 µM. Besides, CPF (0.05, 0.5 and 5 µM) stimulates COX-2 levels at 24 h (p<0.05). We demonstrated that HCB and CPF induce the proangiogenic factors expression. In conclusion, these data highlight that the exposure to endocrine disruptors could contribute to mammary carcinogenesis, inducing angiogenesis proteins.