Abstract 1278: ID3 controlled dynamic Pyk2 localization is important for the mobility of cancer stem cells

Abstract Treatment of brain metastases remains a clinical barrier in breast cancer patients. Secondary breast tumors in the brain are reported to be enriched with breast cancer stem cell (BCSC) markers suggesting that BCSCs infiltrate the brain. Brain infiltration by BCSCs is complex involving detachment from the primary tumor, entering the blood, surviving the microvascular niche, and crossing the blood brain barrier (BBB). It is critical to understand how BCSCs move through the BBB to prevent brain metastases. Nuclear respiratory factor 1 (NRF1) transcription factor, Pyk2 non-receptor tyrosine kinase, and inhibitor of differentiation protein 3 (ID3) have been shown to contribute to the pathogenesis of cancer through inducing CSCs or increasing mobility of these cells. Recently, we showed that NRF1-induced BCSCs crossed the BBB which were guided by ID3 overexpressing endothelial stem cells. In this study, we investigated the NRF1/ID3/Pyk2 axis contributing to BCSCs mobility. NRF1 promoted migration of BCSCs and mesenchymal MDAMB231 cells through brain endothelial cells cultured with astrocytes. ID3 overexpressing endothelial cells promoted adhesion with BCSCs and mobility of BCSCs across the BBB model. In addition, ID3 controlled Pyk2 localization which is important for mobility of stem cells and cancer cells. Endothelial cells were treated with a known risk factors for breast cancer, 17β-estradiol (E2) and environmental pollutant PCB153. Treatment with PCB153 or E2 showed increased growth of BCSCs tumor spheroids and mobility of ESCs. Exosomal ID3 released from endothelial cells also supported the growth of BCSCs and provide the basis for paracrine effects by endothelial stem cells associated with breast tumors. These findings show for the first time a novel role for ID3 and Pyk2 by which endothelial stem cells support breast tumor metastases where they most likely facilitate the colonization, survival, and proliferation of BCSCs. This knowledge is important for pre-clinical testing of NRF1/ID3/Pyk2 modifying agents to prevent the spread of breast cancer to the brain. Citation Format: Jayanta Das, Alok Deoraj, Deodutta Roy, Quentin Felty. ID3 controlled dynamic Pyk2 localization is important for the mobility of cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1278.