In contrast, the combination of G28UCM with the monoclonal antibody cetuximab resulted in an antagonistic effect. Taken together, these results support that the interactions between FASN and HER proteins are restricted to HER2 and do not involve the HER1 receptor. On the other hand, EGCG showed only an additive interaction with trastuzumab and an antagonistic interaction with lapatinib, that gefitinib, erlotinib and cetuximab, which may be in part related to the lower cytotoxic activity of EGCG by itself. We also addressed the molecular inter actions of G28UCM, Inhibitors,Modulators,Libraries analysing FASN protein levels, apoptosis, and the phosphorylated forms of HER2, AKT and ERK1 2 proteins after G28UCM combined with trastuzumab, erlotinib, gefitinib or lapatinib treatment.

Trastuzumab and HER tyrosine kinase Inhibitors,Modulators,Libraries inhibitors displayed molecular synergis tic interaction with G28UCM. This synergistic effect was accompanied by increased apoptosis and seemed to be mediated by abrogation of the activation of HER2, AKT and ERK1 2 when the drugs are combined. It is impor tant that the synergistic molecular effects observed with G28UCM in combination with trastuzumab, erlotinib, gefitinib or lapatinib followed the same pattern than the cellular effects. These in vitro cellular and molecular synergistic results support the in vivo evaluation of these agents in a combination regimen. Finally, we used stable cell lines derived from the AU565 cells that were resistant to either Inhibitors,Modulators,Libraries trastuzumab or lapatinib to test the antican cer properties of G28UCM.

In these cells, in which the cytotoxicity of trastuzumab and lapatinib were almost lost, we observed that the cytotoxic activity of G28UCM in the resistant cells and in the parental cells was simi lar. The activity of G28UCM in Inhibitors,Modulators,Libraries this model of resistance to anti HER2 treatments is consistent with a previous report that observed that trastuzumab resistant breast cancer cells were sensitive to EGCG. Furthermore, our results also show that, even after long term expo sure to trastuzumab and lapatinib, resistant cells contin ued to overexpress FASN. Conclusions In summary, our findings provide a rationale for the pre clinical development of G28UCM either alone or in combination with anti HER agents in HER2 overex pressing breast cancer. Inhibitors,Modulators,Libraries In addition, we report the effect of G28UCM on breast cancer cells resistant to trastuzu mab or lapatinib. Our data support the study of G28UCM as a potential therapeutic agent, obviously either alone or in combination, against in vivo HER2 tumours that have progressed on trastuzumab and lapatinib. Future studies will focus on testing the in vivo activity of G28UCM in mice bearing trastuzumab and lapatinib resistant xenografts. Tobacco smoke is strongly linked to the onset of various types of human malignancies.