A novel function of IRF9 in acute pancreatitis by modulating cell apoptosis, proliferation, migration, and suppressing SIRT1-p53

MZB1 regulates cellular proliferation, mitochondrial dysfunction, and inflammation and targets the PI3K-Akt signaling pathway in acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) is a pathological condition characterized by the premature release and activation of trypsinogens and other enzyme precursors. In severe cases, the mortality rates are in the range of 20-30% and may even be as high as 50%. Though various prophylaxes are available for AP, the mechanism of its progression is unclear. Marginal zone B and B-1 cell-specific protein 1 (MZB1) is found in the endoplasmic reticulum (ER) where it is expressed exclusively in the B cells there. MZB1 promotes proliferation, inhibits apoptosis, invasion, and inflammation, and mitigates mitochondrial damage in cells. However, the importance of MZB1 in AP has not yet been determined.

METHODS

Differentially expressed genes (DEGs) between healthy pancreatic cells and those affected by AP were identified using datasets from Gene Expression Omnibus (GEO) datasets. Relative differences in MZB1 expression between normal and diseased tissues and cells were validated in vivo using a rat AP model induced with 4% (w/v) sodium taurocholate and in vitro using the AR42J rat pancreatic cell line exposed to caerulein (CAE). Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2`-deoxyuridine (EdU) assays were performed to detect and compare normal and pathological cell proliferation. Flow cytometry was employed to assess and compare cellular apoptosis. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot (WB) were applied to evaluate the apoptotic factors Bax and Bcl. The inflammatory factors interleukin (IL)-6 and IL-1β were quantified using Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR techniques. Mitochondrial function was evaluated using assays for reactive oxygen species (ROS) and tetramethylrhodamine methyl ester (TMRM). WB and qRT-PCR were utilized to measure the expression levels of the PI3K-Akt signaling pathway, followed by a rescue experiment involving the inhibitor of wortmannin.

RESULTS

MZB1 was upregulated in the AP cases screened from the GEO datasets, the rat AP model, and the AR42J cells exposed to CAE. Overexpression of MZB1 enhanced the growth and supressed the cell death of AR42J cells while also activating the PI3K-Akt signaling pathway. MZB1 knockdown led to mitochondrial dysfunction and exacerbated inflammation. The rescue experiment demonstrated that MZB1 enhanced proliferation and inhibited apoptosis, mitochondrial dysfunction, and inflammation in pancreatic cells through the PI3K-Akt pathway.

CONCLUSIONS

AP cells and tissues exhibited markedly elevated levels of MZB1 expression compared to their healthy counterparts. MZB1 overexpression promoted proliferation and supressed apoptosis, mitochondrial dysfunction, and inflammation in pancreatic cells through the positive regulation of the PI3K-Akt signaling pathway.

The Transcription Factor IRF9 Promotes Colorectal Cancer via Modulating the IL-6/STAT3 Signaling Axis

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, and innate immune responses and inflammation are known to affect the course of disease. Interferon (IFN) signaling in particular is critical for modulating inflammation-associated diseases including CRC. While the effects of IFN signaling in CRC have been studied, results have been conflicting. Furthermore, individual molecules in the IFN pathway that could be therapeutically targeted have distinct functions, with many of their diverse roles in CRC remaining unclear. Here, we found that IRF9 had an oncogenic effect in CRC; loss of IRF9 reduced tumorigenesis in both azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced and spontaneous CRC models. IRF9 also reduced DSS-induced colitis and inflammation in the colon, but it had no effect on the NF-κB and MAPK signaling activation. Instead, IRF9 enhanced the transcription and production of the inflammatory cytokine IL-6. By promoting IL-6 release, IRF9 drove the activation of pro-oncogenic STAT3 signaling in the colon. Overall, our study found that IRF9 promoted the development of CRC via modulation of the IL-6/STAT3 signaling axis, identifying multiple potential targets and suggesting new therapeutic strategies for the treatment of CRC.

Identification and Validation of Hub Genes in Acute Pancreatitis and Hypertriglyceridemia

BACKGROUND

The pathogenesis of acute pancreatitis (AP) and the relationship between acute pancreatitis and hypertriglyceridemia are complex and not fully understood. The purpose of this study was to identify the hub genes along with common differentially expressed genes (DEGs) between acute pancreatitis and hypertriglyceridemia.

METHODS

We downloaded three gene expression profiles of AP and one gene expression profile of hypertriglyceridemia from the Gene Expression Omnibus (GEO) database and filtered the DEGs based on the above four datasets. Next, we identified the hub genes by performing the Gene Ontology (GO) term analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction (PPI) construction. We also constructed the miRNA-hub gene network and established mouse models with hypertriglyceridemia and AP using a high-fat diet and injection of caerulein (CAE), respectively. Finally, the immunohistochemical analysis was used to verify the differential expressions of hub genes in AP, hypertriglyceridemia, and normal pancreatic tissue.

RESULTS

A total of 105 DEGs associated with AP and 149 DEGs associated with hypertriglyceridemia were identified. Additionally, we identified six hub genes of AP, all of which were closely related to the cytoskeleton while two DEGs genes were common in both AP and hypertriglyceridemia. We also verified their expression in mouse models. Finally, a network of miRNA-mRNA was also constructed, and the top seven interactive miRNAs (hsa-mir-1-3p, hsa-mir-5195-3p, hsa-mir-145-5p, hsa-let-7b-5p, hsa-mir-10b-5p, hsa-mir-206, and hsa-mir-613) targeting the most hub genes were identified.

CONCLUSION

Overall, we identified six hub genes associated with AP and two common DEGs associated with AP and hypertriglyceridemia along with seven miRNAs that may regulate AP. This study could provide new ideas for further elucidation of the pathogenesis of hypertriglyceridemia-induced acute pancreatitis in the future.

The sirtuin 1 activator SRT1720 alleviated endotoxin-induced fulminant hepatitis in mice

The metabolic sensor sirtuin 1 (SIRT1) also functions as a checkpoint in inflammation, and SRT1720 is a highly active and selective SIRT1 activator shown to alleviate inflammatory injury in several recent experimental studies. In the present study, the potential effects and underlying mechanisms of SRT1720 on lipopolysaccharide (LPS)-induced fulminant hepatitis in D-galactosamine (D-Gal)-sensitized mice were investigated. The results indicated that treatment with SRT1720 inhibited LPS/D-Gal-induced elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), alleviated the histological abnormalities, suppressed the induction of tumor necrosis factor alpha (TNF-α) and IL-6, mitigated the phosphorylation of c-Jun N-terminal kinase (JNK), downregulated the activities of caspase 8, caspase 9 and caspase 3, decreased the level of cleaved caspase 3, reduced the TUNEL-positive cells, and improved the survival rate of the LPS/D-Gal-exposed mice. These data indicated that treatment with the SIRT1 activator SRT1720 alleviated LPS/D-Gal-induced fulminant hepatitis, which might be attributed to the suppressive effects of SRT1720 on TNF-α production and the subsequent activation of the apoptosis cascade.

Interferon Regulatory Factor 9 Promotes Lung Cancer Progression via Regulation of Versican

Simple Summary

Lung cancer is the leading cause of cancer-related deaths worldwide, accounting for more than 1.6 million deaths per year. The tumor microenvironment (TME) has been shown to play a crucial role in tumor progression and metastasis, and transcription factors link TME signaling to oncogenesis. Type I interferons (IFNs) are strong immune modulators that possess antiproliferative and proapoptotic properties. In this study, we investigated the role of the transcription factor interferon regulatory factor 9 (IRF9) in the IFN pathway in lung cancer. We performed in vitro and in vivo experiments to reveal the oncogenic properties of IRF9, which was highly upregulated in lung adenocarcinoma. For the first time, we showed that IRF9 binds to the promoter of the known oncogene versican, regulates its expression, and thereby promotes oncogenic activity.

Abstract

Transcription factors can serve as links between tumor microenvironment signaling and oncogenesis. Interferon regulatory factor 9 (IRF9) is recruited and expressed upon interferon stimulation and is dependent on cofactors that exert in tumor-suppressing or oncogenic functions via the JAK-STAT pathway. IRF9 is frequently overexpressed in human lung cancer and is associated with decreased patient survival; however, the underlying mechanisms remain to be elucidated. Here, we used stably transduced lung adenocarcinoma cell lines (A549 and A427) to overexpress or knockdown IRF9. Overexpression led to increased oncogenic behavior in vitro, including enhanced proliferation and migration, whereas knockdown reduced these effects. These findings were confirmed in vivo using lung tumor xenografts in nude mice, and effects on both tumor growth and tumor mass were observed. Using RNA sequencing, we identified versican (VCAN) as a novel downstream target of IRF9. Indeed, IRF9 and VCAN expression levels were found to be correlated. We showed for the first time that IRF9 binds at a newly identified response element in the promoter region of VCAN to regulate its transcription. Using an siRNA approach, VCAN was found to enable the oncogenic properties (proliferation and migration) of IRF9 transduced cells, perhaps with CDKN1A involvement. The targeted inhibition of IRF9 in lung cancer could therefore be used as a new treatment option without multimodal interference in microenvironment JAK-STAT signaling.