Identification of FOXP3+ epithelial cells contributing to pancreatic proliferation and angiogenesis

Abstract

Forkhead box protein 3 (FOXP3), traditionally recognized as a specific transcription factor for regulatory T cells (Tregs), has also been identified in various tumor epithelial cells (named as cancer-FOXP3, c-FOXP3). However, the natural state and functional role of FOXP3 positive tumor epithelial cells remain unknown. Monoclonal cells expressing varying levels of c-FOXP3 were isolated from established PANC-1 cells using limited dilution. Whole-transcriptome sequencing and weighted gene co-expression network analysis (WGCNA) were conducted on these subsets, followed by in vitro and in vivo functional investigations. In addition, we identified c-FOXP3+E-cadherin- epithelial cells in human pancreatic cancer tissues after radical resection by immunofluorescence co-staining. We also investigated the connection between c-FOXP3+E-cadherin- epithelial cells and their clinicopathological features. Our study uncovered a distinct subset of c-FOXP3+ tumor epithelial cells characterized by reduced E-cadherin expression. C-FOXP3+E-cadherin- cells displayed significant proliferation potential and pro-angiogenic effect through the expression of chemokines, including C-X-C motif ligand 1 (CXCL1), C-X-C motif ligand 5 (CXCL5), and C-X-C motif ligand 8 (CXCL8). Notably, higher counts of c-FOXP3+E-Cadherin- cells correlated with poorer prognosis, lower tumor differentiation, lymph node metastasis, and vascular invasion in pancreatic ductal adenocarcinoma (PDAC). In conclusion, this work revealed the stable expression of FOXP3 in tumor epithelial cells, marking a distinct subset. C-FOXP3+E-cadherin- epithelial cells exhibit active proliferation and promote angiogenesis in a vascular endothelial growth factor A (VEGFA) independent manner. These findings provide novel insights into PDAC prognosis and therapeutic avenues.