Inhibition of focal adhesion kinase suppresses the adverse phenotype of endocrine-resistant breast cancer cells and improves endocrine response in endocrine-sensitive cells

International audienceAcquired resistance to endocrine therapy in breast cancer is a major clinical problem. Previous reports have demonstrated that cell models of acquired endocrine resistance have altered cell–matrix adhesion and a highly migratory phenotype, features which may impact on tumour spread in vivo. Focal adhesion kinase (FAK) is an intracellular kinase that regulates signalling pathways central to cell adhesion, migration and survival and its expression is frequently deregulated in breast cancer. In this study, we have used the novel FAK inhibitor PF573228 to address the role of FAK in the development of endocrine resistance. Whilst total-FAK expression was similar between endocrine-sensitive and endocrine-resistant MCF7 cells, FAK phosphorylation status (Y397 or Y861) was altered in resistance. PF573228 promoted a dose-dependent inhibition of FAK phosphorylation at Y397 but did not affect other FAK activation sites (pY407, pY576 and pY861). Endocrine-resistant cells were more sensitive to these inhibitory effects versus MCF7 (mean IC for FAK pY397 inhibition: 0.43 μM, 0.05 μM and 0.13 μM for MCF7, TamR and FasR cells, respectively). Inhibition of FAK pY397 was associated with a reduction in TamR and FasR adhesion to, and migration over, matrix components. PF573228 as a single agent (0–1 μM) did not affect the growth of MCF7 cells or their endocrine-resistant counterparts. However, treatment of endocrine-sensitive cells with PF573228 and tamoxifen combined resulted in greater suppression of proliferation versus single agent treatment. Together these data suggest the importance of FAK in the process of endocrine resistance, particularly in the development of an aggressive, migratory cell phenotype and demonstrate the potential to improve endocrine response through combination treatment

Angiotensin II-induced activation of cyclin D1 is mediated by Egr-1 in CHO-AT1A cells and involves Ras/MEK/ERK, PI3-K and SHP-2 activities.

30 septembre - 2 octobr

Angiotensin II-induced activation of cyclin D1 is mediated by Egr-1 in CHO-AT1A cells and involves Ras/MEK/ERK, PI3-K and SHP-2 activities

24-27 octobr

Role of Immunoglobulins G1 and G2 in Anaphylactic Shock in the Guinea Pig

Heating serum from actively sensitised guinea pigs did not remove its ability to sensitise recipient animals in vivo and parenchymal lung strips in vitro to anaphylaxis. Thermoresistant antibodies should thus account for the transferable sensitising effect, which persists for at least 9 days. IgG1 and IgG2, contained in the serum, were separated by affinity chromatography to determine the importance and the participation of these subclasses in passive anaphylactic shock. IgG1, present in smaller amounts than IgG2, was more effective in sensitising isolated lung strips. The intravenous administration of ovalbumin to guinea pigs, which had been injected with 0.8 mg/kg of IgG1 or 2 mg/kg of IgG2 9 days beforehand, induced an intense bronchoconstriction with leucopenia and moderate thrombopenia, suggesting an as yet undescribed role for IgG2 in passive tissue sensitisation. The use of mepyramine, an antagonist of the histamine H&lt;sub&gt;1&lt;/sub&gt; receptor, WEB 2086, an antagonist of platelet-activating factor, and nordihydroguaiaretic acid, a dual inhibitor of cyclooxygenase and lipooxygenase, alone or associated, demonstrated that the anaphylactic contraction of lung strips from guinea pigs sensitised by IgG1 is mediated by histamine and arachidonate derivatives, whereas that of lung strips from guinea pigs sensitised with IgG2 is mostly mediated by histamine. In addition, the association of the three potential antagonists slightly reduced the anaphylactic contraction of lung strips provided by guinea pigs sensitised by serum. Our results, using a sensitisation procedure considered until now to involve exclusively IgE antibodies, indicate that IgG1 and IgG2 are in fact the essential antibodies for passive anaphylactic shock in the guinea pig.</jats:p