Abstract 3331: PID1, a candidate tumor suppressor in pediatric and adult brain tumors, is a novel interacting partner for a cell surface receptor

Abstract

Abstract BACKGROUND: PID1 is higher in fat from obese patients and is an inhibitor of insulin receptor signaling. We reported that PID1 is a novel inhibitor of medulloblastoma and glioma cell growth, and its mRNA level is highly correlated with survival across multiple independent datasets of these tumors. PID1 harbors a phosphotyrosine binding domain and is predicted to interact with proteins harboring NPXY motifs. We therefore hypothesized that PID1 will interact with phosphotyrosine-binding (PTB) domain containing protein(s) that may be important in brain tumors, and will modulate its/their signaling. Here we report PID1 interactions with one of these proteins and determine its biological consequences. METHODS: Experiments consisted of immunoprecipitations, transient transfections, and western blotting. Functionally, assays included cell culture, flow cytometry for proliferation using BrdU/7AAD and apoptosis using AnnexinV/7AAD. Plasmids were pCMV-AN-HA-PID1(2) or control or the protein of interest in pcDNA3.1. Cell lines used were glioblastoma, medulloblastoma, atypical teratoid rhabdoid (ATRT), HEK293, and cells deficient or intact in PID1. RESULTS: We demonstrate co-immunoprecipitation of PID1 with a receptor that is considered important in cancer. Immunoprecipitation was both in HEK293T cells overexpressing both proteins and in native brain tumor cell lines with/without overexpression. While tyrosine in the NPXY motifs was not required for the interaction, mutating the kinase domain of the receptor or overall inhibition of tyrosine phosphorylation impaired the interaction with PID1. Different domains in PID1 differentially co-immunoprecipitated with the receptor. Interestingly, mouse embryo fibroblasts without PID1 showed increased growth factor-dependent tyrosine phosphorylation of this protein and increased growth factor-induced proliferation. Identity of the receptor will be disclosed at the meeting. CONCLUSIONS: These data point to PID1 as a novel interacting partner and regulator of this receptor’s biological effects and signaling in brain tumors. Note: This abstract was not presented at the meeting. Citation Format: Anat Erdreich-Epstein, Xiuhai Ren. PID1, a candidate tumor suppressor in pediatric and adult brain tumors, is a novel interacting partner for a cell surface receptor [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 3331. doi:10.1158/1538-7445.AM2017-3331