Abstract 1876: Cell cycle-dependent front polarized cell migration requires Aurora kinase A

Abstract

PROBLEM- Metastasis accounts for 90% of deaths from carcinomas. BACKGROUND- To initiate migration, epithelial cells must front-rear polarize and reorganize the microtubule cytoskeleton directed toward the lamillipodia or leading edge. During mitosis, centrosome maturation, duplication, spindle pole assembly and chromosome segregation require Aurora kinase A (AURKA), which is optimally active when complexed with TPX2. Accumulating evidences identify non-mitotic functions for AURKA, such as cell migration and ciliary reorganization. Overexpression of AURKA leads to tumorigenesis in breast cancer. Mechanisms that activate non-mitotic AURKA and promote cell migration as well as metastasis are yet to be uncovered. RESULTS- In a large breast cancer tissue microarray (n= 3,175), the abundance of phosphorylated RHAMM (a substrate of AURKA) predicted overall and relapse-free survival in ER-negative, basal-subtype, and triple negative breast tumors. We studied the AURKA-TPX2-RHAMM signaling axis in mammary (MCF10A and nMUMG-FUCCI) and HeLa cells. In scratch wound assays, migratory cells were found to have front-polarized centrosomes, which correlated with G2 cell cycle phase, phosphorylated AURKA and elevated microtubule nucleation at centrosomes. Small molecule inhibition of Aurora kinase activity impaired centrosome polarity and retarded the kinetics of cell migration. In parallel, silencing RHAMM altered TPX2 location as indicated by immunofluorescence and immuno-EM, which located TPX2 to the nuclear envelope and nuclear pore basket. Nuclear import of recombinant TPX2 was attenuated in RHAMM silenced cells and nuclear envelope accumulation was elevated. CONCLUSION- The AURKA-TPX2-RHAMM axis regulates centrosome polarity, microtubule nucleation and directional cell migration while phosphorylated RHAMM predicts survival in aggressive forms of breast cancer. Citation Format: Tony Lok Heng Chu, Lixin Zhou, Jennifer Won, Pooja Mohan, Oksana Nemirovsky, Abbas Fotovati, Torsten Nielsen, Nelly Pante, Christopher Maxwell. Cell cycle-dependent front polarized cell migration requires Aurora kinase A [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1876. doi:10.1158/1538-7445.AM2017-1876