Abstract LB-C05: The autism and schizophrenia-associated CYFIP1 protein is required for pancreatic tumor growth and presents a potential therapeutic target
Authors: Couto Kiley , Strickland Matthew , Liao Tiffany , Najem Mortada , Fulgham Aaron , Apte Ameya , Huang Pearl , Hurov Jonathan , Lantermann Alexandra 
Published: March 2020

Abstract
The pancreas is highly innervated with sensory, autonomic and enteric neurons, and recent studies have highlighted the crosstalk between neurons and pancreatic cells and their potential role in driving tumorigenesis and promoting metastasis. Published data has shown that ablation of sensory neurons in models of pancreatic ductal adenocarcinoma (PDAC) resulted in delayed tumor initiation and progression. In addition, perineural invasion (PNI), the invasion of tumor cells along the nerve, is a pathological characteristic frequently observed in PDAC. PNI has been detected in early stages of pancreatic cancer and associated with a poor outcome. We hypothesized that PDAC tumor cells express neuronal genes which may be playing a role in enabling tumor-nerve interactions and promoting PDAC tumorigenesis. Here we used pooled sgRNA CRISPR screening to probe a library of 5000 sgRNAs targeting 800 neuronal genes. We selected three established (MiaPaca-2, Panc-1 and BxPC3) and two patient derived human PDAC cell lines (PAXF1657 and PAXF1997) and performed in vitro and in vivo CRISPR screens. sgRNAs targeting the CYFIP1 gene were negatively selected across multiple cell line models in vitro and in vivo. Cytoplasmic FMR1 interacting protein 1 (CYFIP1) is a protein that has been described to regulate actin polymerization and protein translation through two distinct protein complexes. CYFIP1 is a member of the heteropentameric WAVE regulatory complex (WRC) which includes CYFIP1, WAVE, NAP1, ABI, and HSPC300. Rac1 binding to CYFIP1 results in activation of WRC, allowing WAVE to interact with Apr2/3 and enabling actin polymerization. In addition, CYFIP1 can interact with fragile X mental retardation protein (FMRP) and eIF4E, acting as a translation repressor. CYFIP1 is highly expressed at excitatory synapses of neurons and is required for proper dendritic spine morphology. CYFIP1 has been linked to neurological and neuropsychiatric conditions such as autism, epilepsy and schizophrenia due to its location in a chromosomal region (15q11.2) with frequent copy number variations. In order to validate the pooled CRISPR screen results we individually knocked out CYFIP1 in PDAC cancer cell lines. We were able to show that knockout of CYFIP1 reduced proliferation of PDAC cells in vitro and dramatically reduced tumor growth in vivo. Additionally, knockout of CYFIP1 resulted in reduced protein levels of WRC members WAVE1 and NCKAP1, suggesting destabilization of the complex. The mechanism by which CYFIP1 promotes tumor growth has yet to be elucidated, but our data shows that CYFIP1 is playing a critical role in PDAC tumorigenesis and is a potential therapeutic target.
Citation Format: Kiley Couto, Matthew Strickland, Tiffany Liao, Mortada Najem, Aaron Fulgham, Ameya Apte, Pearl Huang, Jonathan Hurov, Alexandra Lantermann. The autism and schizophrenia-associated CYFIP1 protein is required for pancreatic tumor growth and presents a potential therapeutic target [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-C05. doi:10.1158/1535-7163.TARG-19-LB-C05