Abstract P1-01-08: DPYSL3 modulates proliferation and migration in claudin-low breast cancer

Abstract

Abstract Cancer is often driven by deregulated protein kinases pathways including breast cancer. To profile the kinome at the protein level we are developing a kinase pulldown (KiP) proteomic platform that uses multiple kinase inhibitors conjugated to sepharose beads for protein kinase profiling. Mass spectrometry-base tryptic peptide sequencing is used to identify and quantify the kinome in an unbiased manner. To date, we have profiled and analyzed the kinomes of more than 50 breast cancer PDX model systems that include all five breast cancer subtypes. In these analyses we have begun to explore the kinome interactome because we have observed that KiP also pulls down breast cancer subtype specific kinase interacting proteins that may represent new biological insights. For example we have consistently identified dihydropyrimidinase-like 3 (DPYSL3) in p21-activated kinase (PAK) inhibitor KiP interactome in the claudin-low WHIM12 PDX model. DPYSL3 is an intracellular phosphoprotein known to play a role in cell migration and metastasis. However it remains to be seen if DPYSL3 functions as a suppressor or a promoter of metastasis. We therefore generated DPYSL3 knock-down cell lines to evaluate function in claudin-low breast cancer. Proliferation levels of DPYSL3 depleted Claudin-low WHIM12 cells (DPYSL3-) were lower than those of control WHIM 12 (DPYSL3+) cells. In contrast, migration levels of DPYSL3- WHIM12 were greater than those of control cells, suggesting a pivotal role for DPYSL3 in several cellular physiologies. Additionally the activity of a PAK inhibitor (FRAX597) on migration appeared to require DPYSL3, as the inhibitory effect of FRAX579 on migration in WHIM12 was lost when DPYSL3 expression was depleted. Additionally we find that only the long isoform of DPYSL3, not a short isoform, interacts with PAK to regulate migration, suggesting that alternative splicing of DPYSL3 may an important to the control of migration. Furthermore Snail is also negatively regulated DPYSL3 with elevated expression in DYPSL3- cells. In conclusion, the study of the kinome interactome in breast cancer PDX identified DPYSL3 as regulator of the PAK family of kinases in a claudin low breast cancer. DPYSL3 is necessary for PAK to promote migration and may play a pivotal role in complex cellular transitions from a proliferative state versus an EMT/cell migratory state. Citation Format: Matsunuma R, Chan DW, Kim B-J, Singh P, Han A, Malovannaya A, Perou CM, Ellis MJ. DPYSL3 modulates proliferation and migration in claudin-low breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-08.