Enhanced release of ciliary extracellular vesicles suppresses cell migration and promotes cell aggregation.

A primary cilium is a hair-like organelle that protrudes from the cell surface in many cell types. Growing evidence indicates that extracellular vesicles are released from primary cilia, and research is increasingly focused on defining the functions of these cilia-derived extracellular vesicles (EVs). EVs are known to modulate the behavior of various cancer cells, and structural and functional abnormalities in primary cilia have been reported in multiple cancer types. We previously demonstrated that PANC-1 cells, a human pancreatic ductal adenocarcinoma cell line, acquire enhanced primary cilia formation after surviving solitary culture conditions, and that their cilia contribute to tumor-like cell mass formation. Here, we explored part of the underlying mechanism of this phenotype by investigating the contribution of EVs released from the primary cilia of PANC-1 cells. PANC-1 clones generated by limiting dilution exhibited enhanced ciliogenesis and distinct ciliary morphologies compared with parental cells. These clones also released higher levels of cilia-derived EVs, including an expanded population of freely floating EVs within the culture environment. Biochemical analyses further showed that this increase was selective for primary cilia-derived EVs rather than reflecting a global rise in total EV production. Functionally, EV fractions enriched in cilia-derived EVs suppressed parental PANC-1 cell migration, altered cell morphology, and promoted cell aggregation, mimicking key behavioral traits of solitary condition-surviving PANC-1 clones. Together, these findings identify enhanced release of primary cilia-derived EVs as a distinct feature of PANC-1 cells adapted to solitary growth and suggest their potential involvement in the malignant and metastatic behaviors of pancreatic cancer.Key words: primary cilia, PDAC, extracellular vesicles, cell migration, cell aggregation.