Abstract A60: AURKA interaction with MEK1/2 complex and its role in promoting breast cancer cell metastasis

Abstract

Abstract Background: Aurora-A (AURKA) belongs to the family of serine-threonine kinases that are crucial for cell cycle control. In particular, AURKA controls centrosome function, mitotic spindle formation, and proper chromosome segregation. In contrast to the well-defined function of AURKA in normal cells, the role of AURKA in malignant transformation and cancer progression is still under investigation. Here, we report that AURKA directly interacts with MEK1/2 kinase and induces chemotaxis of breast cancer cells. Results: We demonstrated that overexpression of AURKA in luminal ER+ MCF-7 cells (MCF-7AURKA) resulted in over 10-fold increase in the number of cells displaying chemotactic response upon stimulation with growth factors when compared to parental MCF-7 cells. Both AURKA inhibitor MLN8237 and MEK1/2 inhibitor PD0325901 reduced migratory properties of MCF-7AURKA cells. In contrast, treatment with the pan RAF inhibitor TAK-632 did not affect chemotactic response of MCF-7AURKA cells. We demonstrated colocalization of AURKA and MEK1/2 immunofluorescence signals in MCF-7AURKA and triple-negative BT549 cells. In situ proximity ligation assay (PLA) revealed the presence of AURKA-MEK1/2 complexes in MCF-7AURKA and BT549 cells, and the notion that AURKA and MEK1/2 formed cellular complexes was confirmed with co-immunoprecipitation experiments. In vitro kinase assays with recombinant AURKA and MEK1 proteins showed that AURKA kinase could directly phosphorylate MEK1. Incubation of MCF-7AURKA and BT549 cells with the AURKA-specific inhibitors MLN8237 or MK8745 resulted in over a 2-fold increase in the level of pERK1/2 compared to the untreated controls. Treatment with the pan RAF inhibitor TAK-632 did not diminish MLN8237-induced pERK1/2, whereas treatment with the MEK1/2 specific inhibitor PD0325901 completely abrogated MLN8237-induced activation of ERK1/2. Conclusions: Our data present a novel AURKA-MEK1/2 interaction that contributes to the increased chemotaxis of breast cancer cells. The results suggest that AURKA negatively regulates MEK1 through a novel, direct phosphorylation event, possibly leading to constitutive activation of MEK2 and increased chemotaxis. The combined treatment of AURKA and MEK1/2 inhibitors represents a new therapeutic approach to decrease metastatic potential of breast cancer cells and delay tumor progression. The in-depth analysis of the AURKA-MEK1/2 complexes as well as in vivo studies testing the efficacy of combining AURKA and MEK1/2 inhibitors on patient-derived xenografts are currently in progress. Citation Format: Malgorzata Gil, Archana Chidambaram, Thaer Khoury, Kazuaki Takabe, Igor Puzanov, Irwin H. Gelman, Antonino B. D’Assoro, Evanthia Galanis, Mateusz Opyrchal. AURKA interaction with MEK1/2 complex and its role in promoting breast cancer cell metastasis [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A60.