Exploring the potential role of palladin in modulating human CAF/ECM functional units

Abstract

AbstractFibroblasts, crucial for maintaining tissue homeostasis, significantly shape the tumor microenvironment (TME). In pancreatic cancer, a highly aggressive malignancy, cancer‐associated fibroblast (CAF)/extracellular matrix (ECM) units dominate the TME, influencing tumor initiation, progression, and treatment responses. Palladin, an actin‐associated protein, is vital for fibroblast structural integrity and activation, playing a key role in CAF/ECM functionality. Palladin interacts with cytoskeletal proteins such as alpha‐actinin (α‐Act) and can therefore regulate other proteins like syndecans, modulating cytoskeletal features, cell adhesion, integrin recycling, and signaling. In this review, we propose that targeting the palladin/α‐Act/syndecan interaction network could modulate CAF/ECM units, potentially shifting the TME from a tumor‐promoting to a tumor‐suppressive state. In silico data and reported studies to suggest that stabilizing palladin‐α‐Act interactions, via excess palladin, influences syndecan functions; potentially modulating integrin endocytosis via syndecan engagement with protein kinase C alpha as opposed to syndecan binding to α‐Act. This mechanism can then affect the distribution of active α5β1‐integrin between the plasma membrane and known intracellular vesicular compartments, thereby influencing the tumor‐suppressive versus tumor‐promoting functions of CAF/ECM units. Understanding these interactions offers likely future therapeutic avenues for stroma normalization in pancreatic and other cancers, aiming to inhibit tumor progression and improve future treatment outcomes.