Correction: Integration of metabolites from meta-analysis with transcriptome reveals enhanced SPHK1 in PDAC with a background of pancreatitis

Transcriptomic analysis of pancreatic tissue from humans and mice identifies potential gene signatures and unexplored pathways during progression from acute to chronic pancreatitis

BACKGROUND

A comprehensive understanding of the molecular pathogenesis of chronic pancreatitis (CP), a fibroinflammatory disorder of the pancreas, is warranted for the development of targeted therapies. The current study focused on comparing the transcriptomes of pancreatic tissues obtained from patients with CP with those of two rodent models of chemically induced CP to identify dysregulated genes/signaling pathways.

METHODS

Pancreatitis was induced in mice using cerulein and L-arginine. Pancreatic tissues were obtained from humans and mice. The RNA was isolated, and the transcriptomes were generated using the GeneChip Human Transcriptome Array 2.0 and Clariom D Mouse Array respectively. Differentially expressed genes with log2-fold changes ≥ +2 and ≤ -2 were considered for functional and signaling pathway enrichment analysis. The expression of NUCB2, which plays a role in β-cell function, was validated by ELISA in acute pancreatitis (AP) and immune cell responses in AP and CP using flow cytometry.

RESULTS

The current study identifies L-arginine-induced CP as a better model for investigating the pathogenesis of human CP, with greater similarity in dysregulated genes (22%), transcription factors (34%) and enriched pathways (58%) compared to cerulein model (2%, 11% and 9%) respectively. Nesfatin-1, encoded by NUCB2, was decreased in patients with AP (12% nondiabetic, 41% post pancreatitis diabetes). The Th1 immune cell response was greater in the patients with AP (44%), whereas Th17 immune response was greater in patients with CP (18%).

CONCLUSION

Our study highlights potential novel and unexplored pathways involved in inflammation, fibrosis, and pain in CP and paves the way for testing them as putative drug targets using a severe disease model.

Transcriptome and Lipidomic Analysis Suggests Lipid Metabolism Reprogramming and Upregulating SPHK1 Promotes Stemness in Pancreatic Ductal Adenocarcinoma Stem-like Cells

Cancer stem cells (CSCs) are considered to play a key role in the development and progression of pancreatic ductal adenocarcinoma (PDAC). However, little is known about lipid metabolism reprogramming in PDAC CSCs. Here, we assigned stemness indices, which were used to describe and quantify CSCs, to every patient from the Cancer Genome Atlas (TCGA-PAAD) database and observed differences in lipid metabolism between patients with high and low stemness indices. Then, tumor-repopulating cells (TRCs) cultured in soft 3D (three-dimensional) fibrin gels were demonstrated to be an available PDAC cancer stem-like cell (CSLCs) model. Comprehensive transcriptome and lipidomic analysis results suggested that fatty acid metabolism, glycerophospholipid metabolism, and, especially, the sphingolipid metabolism pathway were mostly associated with CSLCs properties. SPHK1 (sphingosine kinases 1), one of the genes involved in sphingolipid metabolism and encoding the key enzyme to catalyze sphingosine to generate S1P (sphingosine-1-phosphate), was identified to be the key gene in promoting the stemness of PDAC. In summary, we explored the characteristics of lipid metabolism both in patients with high stemness indices and in novel CSLCs models, and unraveled a molecular mechanism via which sphingolipid metabolism maintained tumor stemness. These findings may contribute to the development of a strategy for targeting lipid metabolism to inhibit CSCs in PDAC treatment.

Serum Metabolite Biomarkers for Pancreatic Tumors: Neuroendocrine and Pancreatic Ductal Adenocarcinomas-A Preliminary Study

BACKGROUND

Pancreatic cancer is the most common pancreatic solid malignancy with an aggressive clinical course and low survival rate. There are a limited number of reliable prognostic biomarkers and a need to understand the pathogenesis of pancreatic tumors; neuroendocrine (PNET) and pancreatic ductal adenocarcinomas (PDAC) encouraged us to analyze the serum metabolome of pancreatic tumors and disturbances in the metabolism of PDAC and PNET.

METHODS

Using the AbsoluteIDQ^® p180 kit (Biocrates Life Sciences AG, Innsbruck, Austria) with liquid chromatography-mass spectrometry (LC-MS), we identified changes in metabolite profiles and disrupted metabolic pathways serum of NET and PDAC patients.

RESULTS

The concentration of six metabolites showed statistically significant differences between the control group and PDAC patients (p.adj < 0.05). Glutamine (Gln), acetylcarnitine (C2), and citrulline (Cit) presented a lower concentration in the serum of PDAC patients, while phosphatidylcholine aa C32:0 (PC aa C32:0), sphingomyelin C26:1 (SM C26:1), and glutamic acid (Glu) achieved higher concentrations compared to serum samples from healthy individuals. Five of the tested metabolites: C2 (FC = 8.67), and serotonin (FC = 2.68) reached higher concentration values in the PNET serum samples compared to PDAC, while phosphatidylcholine aa C34:1 (PC aa C34:1) (FC = -1.46 (0.68)) had a higher concentration in the PDAC samples. The area under the curves (AUC) of the receiver operating characteristic (ROC) curves presented diagnostic power to discriminate pancreatic tumor patients, which were highest for acylcarnitines: C2 with AUC = 0.93, serotonin with AUC = 0.85, and PC aa C34:1 with AUC = 0.86.

CONCLUSIONS

The observations presented provide better insight into the metabolism of pancreatic tumors, and improve the diagnosis and classification of tumors. Serum-circulating metabolites can be easily monitored without invasive procedures and show the present clinical patients' condition, helping with pharmacological treatment or dietary strategies.