An oncogenic KRAS-driven secretome involving TNFa promotes niche preparation prior to pancreatic cancer onset [co-culture scRNA-seq]
Background: Pancreatic ductal adenocarcinomas (PDACs) are highly lethal and aggressive with oncogenic KRAS being the main oncogenic driver of the disease. PDACs have been extensively profiled at advanced stages, and in advanced disease the tumor microenvironment is a major determinant that critically shapes patient outcomes. Since the molecular events occurring prior to invasive growth remain poorly understood, we aimed to investigate changes in the precancerous epithelium and its surrounding niche. Methods: We acquired time-resolved, single-cell transcriptomic (scRNAseq), and accessible-chromatin data from human pluripotent stem cell-derived pancreatic duct-like organoids (PDLO) inducibly expressing KRASG12D and from various niche cells. Results: Analysis of the pure epithelium already revealed key signatures of matrix remodeling and inflammation-related signaling upon few days of KRASG12D expression. Machine learning captured KRASG12D-dependent transcriptomic classifiers with high prediction accuracy and niche preparatory relevance. Various co-culture approaches followed by scRNAseq and functional validation, including T-cell microfluidics, demonstrated that the KRASG12D-induced PDLO-secretome activates pancreatic stellate cells (PaSCs) and protects precancerous organoids from T cell infiltration. Additional, in silico approaches reconstructed a virtual pancreatic (pre)cancerous space to profile cell-cell interactions between PDLOs and niche cells. TNFa emerged as a top-ranked ligand and was functionally validated to mediate T-cell shielding and PaSC activation. Cyst fluid from 80 prospectively sampled Intraductal Papillary Mucinous Neoplasm (IPMNs) –well-known cystic PDAC precursor lesions– showed a stepwise TNFa rise across LGD (low-grade), HGD (high-grade), and IC (invasive cancer). Conclusion: Our study reveals that oncogenic KRAS orchestrates niche-preparatory programs that precede PDAC formation and highlight a T cell exclusion program governed by epithelial-derived TNFa. Overall design: Single-cell RNA-sequencing (scRNA-seq) of human stem-cell derived pacnreatic duct-like organoids (PDLOs) after treatment with doxycycline to induce KRASG12D expression, either in monoculture, bi-culture with PBMC-derived T cells from healthy donors (biTcells) or bi-culture with human pancreatic stellate cells (biStellate).