Challenges in detecting pre-malignant pancreatic lesions during acute pancreatitis using a serum microRNA assay: a study based on Kras(G12D) transgenic mice

Caerulein-induced acute pancreatitis accelerates the progression of pancreatic intraepithelial neoplasia (PanIN) lesions in a pancreas-specific Kras(G12D) mouse model. The purpose of this study was to explore whether serum microRNAs (miRNAs) can serve as sensitive biomarkers to detect occult PanIN in the setting of acute pancreatitis. Serum miRNA profiles were quantified by an array-based method and normalized by both Variance Stabilization Normalization (VSN) and invariant methods. Individual miRNAs were validated by TaqMan real-time PCR with synthetic spike-in C. elegans miRNAs as external controls. Serum miRNA profiles distinguished Kras(G12D) mice with pancreatitis from wild-type mice without pancreatitis, but failed to differentiate Kras(G12D) mice with pancreatitis from wild-type mice with pancreatitis. Most individual miRNAs that increased in Kras(G12D) mice with pancreatitis were not significantly different between Kras(G12D) mice without pancreatitis and wild-type mice without pancreatitis. Mechanistically, Gene Set Enrichment Analysis (GSEA) of the mRNA array data and immunohistochemical assays showed that caerulein-induced acute pancreatitis involved acinar cell loss and immune cell infiltration, which might contribute to serum miRNA profile changes. This study highlighted the challenges in using sensitive serum miRNA biomarker screening for the early detection of pancreatic malignancies during acute pancreatitis.