Activation of c-Src/HER1/STAT5b and HER1/ERK1/2 Signaling Pathways and Cell Migration by Hexachlorobenzene in MDA-MB-231 Human Breast Cancer Cell Line

CAROLINA PONTILLO; MARÍA ALEJANDRA GARCÍA; DELFINA PEÑA; CLAUDIA COCCA; FLORENCIA CHIAPPINI; LAURA ALVAREZ; DIANA KLEIMAN; ANDREA RANDI

TOXICOLOGICAL SCIENCES

OXFORD UNIV PRESS

Año: 2011 vol. 120 p. 284 - 296

1096-6080

Hexachlorobenzene (HCB) is a widespread environmental pollutant. It is a dioxin-like compound, and a weak ligand of the aryl hydrocarbon receptor (AhR) protein. HCB is a tumor co-carcinogen in rat mammary gland and an inducer of cell proliferation and c-Src kinase activity, in MCF-7 breast cancer cells. This study was carried out to investigate HCB action on c-Src and the human epidermal growth factor receptor (HER1) activities, and their downstream signaling pathways, Akt, ERK1/2 and STAT5b, as well as on cell migration in a human breast cancer cell line, MDA-MB-231. We also investigated whether the AhR is involved in HCB-induced effects. We have demonstrated that HCB (0.05 µM) produces an early increase of Y416-c-Src, Y845-HER1, Y699-STAT5b and ERK1/2 phosphorylation. Moreover, our results have shown that the pesticide (15 min) activates these pathways in a dose dependent manner (0.005, 0.05, 0.5 and 5µM). In contrast, HCB does not alter T308-Akt activation. Pretreatment with a specific inhibitor for c-Src (PP2) prevents Y845-HER1 and Y699-STAT5b phosphorylation. AG1478, a specific HER1 inhibitor, abrogates HCB-induced STAT5b and ERK1/2 activation, whereas, 4, 7-orthophenanthroline and á-naphthoflavone, two AhR antagonists, prevent HCB-induced STAT5b and ERK1/2 phosphorylation. HCB enhances cell migration evaluated by scratch motility, and transwell assays. Pretreatment with PP2, AG1478, and 4,7-orthophenanthroline, suppress HCB-induced cell migration. These results demonstrate that HCB stimulates c-Src/HER1/STAT5b and HER1/ERK1/2 signaling pathways, in MDA-MB-231. c-Src, HER1 and AhR, are involved in HCB-induced increase in cell migration. The present study makes a significant contribution to the molecular mechanism of action of HCB, in mammary carcinogenesis. KEY WORDS: Hexachlorobenzene, MDA-MB-231, cell migration, AhR, c-Src, HER1.