Overcoming Trastuzumab Resistance in Breast Cancer by Targeting Tumor Necrosis Factor Alpha

MERCOGLIANO, MARÍA FLORENCIA; RIVAS, MARTÍN A.; VENTURUTTI, LEANDRO; TKACH, MERCEDES; CORDO RUSSO, ROSALÍA; PROIETTI, CECILIA J.; MARONNA, ESTEBAN; FRAHM, ISABEL; ELIZALDE, PATRICIA V.; SCHILLACI, ROXANA

Barcelona

Congreso; 22nd Biennial Congress of the European Association for Cancer Research; 2012

European Association for Cancer Research (EACR)

Introduction ErbB2 overexpression occurs in ~20% of invasive breast cancer and is associated with poor prognosis. Trastuzumab (T), a monoclonal antibody (Ab) against ErbB2, is given to patients with ErbB2-overexpressing breast cancer. However, the overall response rate is about 26% as a single agent and 40-60% when used in combination with chemotherapy. Failure to respond can be due to intrinsic or acquired resistance to T. We have previously demonstrated that tumor necrosis factor α (TNF) induces ErbB2 transactivation and is able to overcome the inhibitory effect of T on BT-474 and SKBR-3 cells proliferation through the activation of NF-κB. In this work we explored the effect of TNF blockage on the growth of breast cancer cells that exhibit intrinsic resistance to T, using the JIMT-1 cell line.Material and methods. TNF effect was blocked either by siRNA or by the TNF receptor2-FcIgG fusion protein, etanercept (E). For in vivo experiments, nude mice were injected with 3x106 JIMT-1 cells and treated with 5mg/kg E twice a week, 5mg/kg T once a week or both. Control group was injected with human IgG. Histopathological analyses were performed by H&E staining and by IHC for ErbB2 using A0485 Ab. For in vitro experiments, JIMT-1 cells were either transfected with siRNA or treated with 10μg/ml etanercept. T binding was detected by immunofluorescence and flow cytometry analysis. Results and discussion. Western blot (WB) showed that JIMT-1 cells produced the precursor and mature forms of TNF. JIMT-1 xenograft tumors treated with E or T showed no differences in growth compared to IgG-injected mice. However, simultaneous administration of E + T reduced tumor size by 54.1 ± 4.6% (P