Transactivation of ErbB-2 induced by tumor necrosis factor alpha promotes NF-kappaB activation and breast cancer cell proliferation.

RIVAS MA, TKACH M, BEGUELIN W, PROIETTI CJ, ROSEMBLIT C, CHARREAU EH, ELIZALDE PV, SCHILLACI R.

BREAST CANCER RESEARCH AND TREATMENT

SPRINGER

Año: 2009 p. 1 - 14

0167-6806

Tumor necrosis factor alpha (TNFa) is a pleiotropic cytokine which, acting locally, induces tumor growth. Accumulating evidence, including our findings, showed that TNFa is mitogenic in breast cancer cells in vitro and in vivo. In the present study, we explored TNFa involvement on highly aggressive ErbB-2-overexpressing breast cancer cells. We found that TNFa induces ErbB-2 phosphorylation in mouse breast cancer C4HD cells and in the human breast cancer cell lines SK-BR-3 and BT-474. ErbB-2 phosphorylation at Tyr877 residue was mediated by TNFa-induced c-Src activation. Moreover, TNFa promoted ErbB-2/ErbB-3 heterocomplex formation, Akt activation and NF-jB transcriptional activation. Inhibition of ErbB-2 by addition of AG825, an epidermal growth factor receptor/ ErbB-2-tyrosine kinase inhibitor, or knockdown of ErbB-2 by RNA interference strategy, blocked TNFa-induced NFkB activation and proliferation. However, the humanized monoclonal antibody anti-ErbB-2 Herceptin could not inhibit TNFa ability to promote breast cancer growth. Interestingly, our work disclosed that TNFa is able to transactivate ErbB-2 and use it as an obligatory downstream signaling molecule in the generation of mitogenic signals. As TNFa has been shown to be present in the tumor microenvironment of a significant proportion of human infiltrating breast cancers, our findings would have clinical implication in ErbB-2-positive breast cancer treatment.Tumor necrosis factor alpha (TNFa) is a pleiotropic cytokine which, acting locally, induces tumor growth. Accumulating evidence, including our findings, showed that TNFa is mitogenic in breast cancer cells in vitro and in vivo. In the present study, we explored TNFa involvement on highly aggressive ErbB-2-overexpressing breast cancer cells. We found that TNFa induces ErbB-2 phosphorylation in mouse breast cancer C4HD cells and in the human breast cancer cell lines SK-BR-3 and BT-474. ErbB-2 phosphorylation at Tyr877 residue was mediated by TNFa-induced c-Src activation. Moreover, TNFa promoted ErbB-2/ErbB-3 heterocomplex formation, Akt activation and NF-jB transcriptional activation. Inhibition of ErbB-2 by addition of AG825, an epidermal growth factor receptor/ ErbB-2-tyrosine kinase inhibitor, or knockdown of ErbB-2 by RNA interference strategy, blocked TNFa-induced NFkB activation and proliferation. However, the humanized monoclonal antibody anti-ErbB-2 Herceptin could not inhibit TNFa ability to promote breast cancer growth. Interestingly, our work disclosed that TNFa is able to transactivate ErbB-2 and use it as an obligatory downstream signaling molecule in the generation of mitogenic signals. As TNFa has been shown to be present in the tumor microenvironment of a significant proportion of human infiltrating breast cancers, our findings would have clinical implication in ErbB-2-positive breast cancer treatment.