Abnormal Polyamine Metabolism in Pancreatic Epithelial Cells aggravates chronic pancreatitis-associated preneoplastic lesions.

BACKGROUND

Chronic pancreatitis (CP) is an independent risk factor for pancreatic cancer (PC). Investigation of the pathological progression of CP may help to elucidate the mechanisms underlying the progression of preneoplastic lesions in CP.

METHODS

Interleukin-6 (IL-6)and Tumor necrosis factor-alpha (TNF-α) were used to induce inflammatory mouse pancreatic acinar carcinoma cell line 83 (MPC-83) cells, followed by RNA-sequencing to identify differentially expressed genes. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to assess mRNA expression and protein levels, respectively. Flow cytometry was used to quantify CD86- and CD206-positive cells, and the Transwell assays were used to assess cell migration. Methylation-specific PCR (MSP-PCR) was used to assess DNA methylation, and enzyme-linked immunosorbent assay (ELISA) to measure Interferon-gamma (IFN-γ), IL-10, spermine, and spermidine levels. Hematoxylin-Eosin (HE) and Masson staining were used to assess pathological changes and collagen deposition in pancreatic tissues, and immunohistochemistry was used to detect alpha-smooth muscle actin (α-SMA), cluster of differentiation 86 (CD86), and cluster of differentiation 206 (CD206) expression.

RESULTS

Spermine and spermidine levels were elevated in inflammatory MPC-83 cells and the serum and pancreatic tissues of a CP mouse model, respectively. IL-6 and TNF-α increased the mRNA expression of Ornithine decarboxylase (ODC), Spermine synthase (SMS), and Spermidine synthase (SRM), and decreased Spermidine/spermine N1-acetyltransferase 1 (SAT1) mRNA expression. Spermine further increased the mRNA expression of SRY-box 9 (SOX9) and Keratin 19 (KRT19) in inflammatory MPC-83 cells and reduced the DNA methyltransferase 3b (DNMT3B) protein level. Spermine also reduced the methylation of SOX9 and KRT19 in MPC-83 cells. The enhanced migration and M2 polarization of RAW264.7 cells induced by spermine-treated inflammatory MPC-83 cells were reversed by DNMT3B overexpression in inflammatory MPC-83 cells. Finally, in vivo experiments revealed that spermine aggravated CP progression and increased M2 macrophage infiltration into the pancreatic tissues of CP mice.

CONCLUSION

Our results suggest that increased spermine levels in inflammatory MPC-83 cells aggravated CP progression by promoting macrophage migration and M2 polarization of macrophages, possibly through reduced DNA methylation of SOX9 and KRT19. These findings suggest a novel mechanism underlying the progression of preneoplastic lesions in CP.