Abstract 4594: Involvement of receptors tyrosine kinase in the modulation of store-operated calcium entry

Abstract

Abstract A multitude of studies show that alterations in Ca2+ signalling initiate or support the development of hallmarks of cancer. In particular, the role of store-operated Ca2+ entry (SOCE) in tumorigenesis and tumour progression has been subject to intense investigation. SOCE is the main mechanism by which external Ca2+ enters into the cell. It is initiated by depletion of ER Ca2+ stores and mediated by several proteins such as STIM1, an ER transmembrane protein sensing Ca2+ within the ER and ORAI1, a plasma membrane Ca2+ channel. We recently showed that SOC inhibition interfered with EGFR-dependent signalling in non-small cell lung carcinoma cells. In this study, we observed that STIM1 depletion reduced neuregulin-dependent proliferation of breast cancer cells. Since neuregulin binds to ErbB3 and/or ErbB4 and therefore activates ErbB2, this result prompted us to investigate whether ErbB proteins might modulate SOCE. We observed that lapatinib, a dual inhibitor of EGFR and ErbB2, dramatically inhibited SOCE. As expected, lapatinib also inhibited phosphorylation of EGFR, ErbB2 and downstream pathways of both receptors. Specific inhibition of EGFR by erlotinib or gefitinib had no effect on SOCE. In contrast, specific inhibition of ErbB2 by CP724714 mimicked the effects of lapatinib. We also investigated the role of downstream pathways of ErbB2 in the modulation of SOCE. Inhibition of the MAPK and the JAK-STAT pathways does not modify the amplitude of SOCE. Contrariwise, LY294002 and MK2206, two inhibitors of the PI3K pathway, dramatically reduced SOCE. Interestingly, in silico analysis showed that STIM1 might be phosphorylated by Akt. All these results suggest that SOCE is important in the proper function of ErbB2-dependent signalling. This raises the possibility to target molecular mediators of SOCE in order to interfere with the proliferation of cancer cells. Citation Format: Noémie Emeriau. Involvement of receptors tyrosine kinase in the modulation of store-operated calcium entry. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4594.