Abstract 2550: Growth factor-induced cell membrane macroplatforms drive protein kinase signaling for transformed cell growth

Abstract

Abstract Nanoscopic, millisecond-lasting membrane platforms are modeled to constitute main functional signaling units. However, multiple signaling events in cell growth induction, including receptor Tyr-kinase (RTK) stimulation, calcium signaling, cytoplasmic kinase recruitment, operate over much broader space-time frames. Through dynamic confocal/super-resolution/electron-microscopy on living cells, we discovered that signaling competence is acquired through growth factor-induced coalescence of activated growth inducers (RTK, CD9, CD81, CD98, Co-029, CD316, Trop-1, Trop-2, PI3K, PI4K), and downstream effectors (Grb-2, PKCα, ERK, Akt, Src, Syk, ILK, ezrin) into confined segments of the cell membrane (‘docks’), that recursively assemble over hundreds of seconds. Average size (25±5 μm; ~80,000 individual analyses) and lifetime (222±25 sec) of docks extend by orders of magnitude previously recognized space-time frames for cell signaling. Activated/phosphorylated kinases clustered at membrane docks (99% P-Erb-B4; 91% P-Ret; 90% P-PKCα; 90% P-Src). STED super-resolution microscopy revealed up to 10 µm2 signal transducer areas of effector colocalization. Docks >1.0 µm2 accounted for ~90% of colocalizations versus ≈1% of raft-sized domains (<0.005 µm2). FRET-FLIM subsequently indicated that inter-molecular signal transducer interactions are essentially confined at docks. Docks were induced by growth factors (FGF-1, PDGF, EGF>HGF, IGF-1>>SCF/VEGF), were inhibited by Tyr kinase and cytoskeleton inhibitors, and were shown to induce cancer cell proliferation. Citation Format: Saverio Alberti, Valeria Relli, Romina Tripaldi, Pasquale Simeone, Emanuela Guerra, Andrea Sacchetti, Paolo Ciufici, Antonino Moschella, Valeria Caiolfa, Moreno Zamai, Marco Trerotola. Growth factor-induced cell membrane macroplatforms drive protein kinase signaling for transformed cell growth [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 2550.