Mucin 5ac modulates cancer-associated fibroblast heterogeneity through epigenetic reprogramming of precursor cells

Pancreatic cancer (PC) is characterized by extensive desmoplasia, with heterogeneous cancer-associated fibroblasts (CAFs) as a major component. However, the contribution of distinct precursor cells to CAF heterogeneity remains poorly defined. This study investigated the role of Muc5ac in modulating CAF heterogeneity by maturing precursor cells, including adipose-derived mesenchymal stem cells (AD-MSCs), bone marrow-derived MSCs (BM-MSCs), and pancreatic stellate cells (PSCs), into different CAF subsets. RNA sequencing of precursor cells treated with conditioned media from Muc5ac-proficient or -deficient cancer cells revealed distinct transcriptional profiles. Muc5ac significantly modulated the expression of <i>Dnmts</i> and <i>Tets</i> in AD-MSCs, promoting the acquisition of extracellular matrix production, cytokine signaling, and antigen presentation programs, characteristic of both inflammatory (iCAF) and myofibroblastic (myCAF) CAF phenotypes. In PSCs, Muc5ac increased H3K27 acetylation independent of its interactome, which was validated in autochthonous murine models. Transcriptome analysis demonstrated that AD-MSCs contributed 44.4% to the CAF population, followed by PSCs (31.5%) and BM-MSCs (21.6%). Gene Ontology (GO) and KEGG analyses revealed distinct functional programs for each precursor population contributing to CAF heterogeneity. An age-dependent signature in AD-MSC maturation was identified, with a significant positive correlation between serum INHBA and MUC5AC from younger (≤55 yr, <i>n</i> = 20) compared with older (≥75 yr, <i>n</i> = 20) patients.<b>NEW & NOTEWORTHY</b> Cancer-associated fibroblast (CAF) heterogeneity limits effective stromal targeting in pancreatic cancer (PC). This study shows that adipose- and bone marrow-derived mesenchymal stem cells and pancreatic stellate cells intrinsically mature into distinct CAF subtypes. Muc5ac modulates the expression of epigenetic regulators and drives adipose-derived cells to dominate the CAF population. Defining precursor cell-specific CAF programs provides a framework to selectively target tumor-promoting CAFs, offering a potential strategy to improve stroma-targeted therapies in PC.