Abstract 5106: Cell crowding-induced TRPV4 inhibition and relocation to plasma membranes: Implications for a pro-invasive mechanotransduction pathway in DCIS progression

Cell crowding is a common microenvironmental factor influencing disease progression, yet its role in promoting cell invasiveness remains poorly understood. Here, we demonstrate that cell crowding enhances the invasiveness of high-grade ductal carcinoma in situ (DCIS) cells through pro-invasive cell volume reduction. High-grade DCIS cells showed significant volume reduction compared to hyperplasia-mimicking or normal cells under crowded conditions. Mass spectrometry revealed selective relocation of TRPV4, a calcium-permeant ion channel, to the plasma membrane in high-grade DCIS cells, a response absent in less aggressive or normal cells. We found that cell crowding inhibits TRPV4 activity in high-grade DCIS cells, reducing intracellular calcium levels and inducing volume reduction. This inhibition triggers TRPV4 relocation to the plasma membrane, priming it for subsequent activation to counterbalance calcium loss. Analyses of patient-derived breast cancer tissues confirmed TRPV4 association with the plasma membrane specifically in high-grade DCIS, correlating with increased cell invasiveness and motility. Moreover, hyperosmotic stress and pharmacologic TRPV4 inhibition replicated crowding-induced pro-invasive volume reduction, while TRPV4 activation reversed these effects. These findings uncover a novel, selective mechanotransduction pathway in high-grade DCIS that links cell crowding to enhanced invasiveness, shedding light on the biophysical mechanisms driving breast cancer progression. Our results highlight TRPV4 as a potential diagnostic and prognostic biomarker for high-risk DCIS and provide insights into therapeutic interventions targeting cell volume regulation. Citation Format: Xiangning Bu, Nathanael Ashby, Teresa Vitali, Sulgi Lee, Ananya Gottumukkala, Kangsun Yun, Sana Tabbara, Patricia Latham, Christine Teal, Inhee Chung. Cell crowding-induced TRPV4 inhibition and relocation to plasma membranes: Implications for a pro-invasive mechanotransduction pathway in DCIS progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5106.