Activation of TGF-b1 signaling pathway in human breast cancer cell line MDA-MB-231 induced by hexachlorobenzene pesticide

N MIRET; C A PONTILLO; F CHIAPINI; L ALVAREZ; D KLEIMAN; C VENTURA; C COCCA; A RANDI

Edimburgo

Congreso; 50th Congress of the European Societies of Toxicology. EUROTOX; 2014

European Societies of Toxicology

Hexachlorobenzene (HCB) is a widely distributed organochlorine pesticide and a probable human carcinogen. Regional studies showed the presence of this pollutant in mother milk. We demonstrated that HCB induces proliferation, migration and invasion in human breast cancer cells, as well as tumor growth and metastasis in vivo. Transforming Growth Factor b1 (TGFb-1) regulates proliferation, migration, invasion and apoptosis processes. TGFβ-1 binds to membrane receptors and acts via Smad-dependent, as well as Smad-independent pathways (ERK1/2, JNK and p38). We reported that HCB induces ERK1/2 activation and cell migration in human breast cancer cell line MDA-MB-231. Our aim was to investigate HCB (0, 0.005, 0.05, 0.5 and 5 μM) action on TGFb-1 expression and activation, and their Smad-dependent and independent pathways in MDA-MB-231. In addition, we examined if TGFb-1 is involved in HCB-induced migration. HCB exposure increases TGFb-1 expression at 2 and 6 h (250%, p lower than 0.01) and TGFb-1 activation at 2, 6 and 24 h (220%, p lower than 0.01) analysed by Western blot. We found that evaluated TGFb-1 pathways are activated at all assayed doses (p lower than 0.01), but at different times (Smad3: 5 min, 100%, JNK: 15 min, 180%, p38: 5, 15 and 30 min, 50%). HCB enhances Smad3 translocation to the nucleus in a dose-dependent manner after 5 min (p lower than 0.01) by immunocytochemistry. Finally, we found that HCB (0.05 μM) increases cell migration (35%, p lower than 0.01), and this effect is prevented by Smad3 (p lower than 0.01), JNK (p lower than 0.001) and p38 (p lower than 0.001) inhibitors. We demonstrated that HCB stimulates TGFb-1 expression and activation, enhances Smad3, JNK and p38 phosphorylation, and induces cell migration via Smad3, JNK and p38 in MDA-MB-231.