Identification of DEGs in Acute Pancreatitis and Ferroptosis
The GEO database provided the raw data and we extracted DEGs by comparing AP and control group samples. Subsequently, we intersected 259 genes obtained from the Ferroptosis Database with DEGs of GSE109227 to identify ferroptosis DEGs. It showed one downregulated gene and 37 upregulated genes (Table 1). Figure 1 depicts a heat map, volcano plots, and a DEG Venn diagram. In addition, we divided these DEGs into three groups: ferroptosis driver, ferroptosis suppressor, and ferroptosis marker (Table 2).
TABLE1 Acute pancreatitis genes are differentially expressed in ferroptosis
Gene.symbol
|
P.Value
|
logFC
|
Gene.title
|
ID
|
Dusp1
|
9.79E-11
|
4.340851
|
dual specificity phosphatase 1
|
10449284
|
Txnrd1
|
1.41E-06
|
2.213799
|
thioredoxin reductase 1
|
10365260
|
Srxn1
|
4.78E-08
|
3.658947
|
sulfiredoxin 1 homolog (S. cerevisiae)
|
10477061
|
Chac1
|
1.49E-06
|
2.379898
|
ChaC, cation transport regulator 1
|
10474972
|
Slc7a11
|
0.000206
|
2.249066
|
solute carrier family 7 (cationic amino acid transporter, y+ system), member 11
|
10498024
|
Ddit4
|
1.29E-07
|
2.639451
|
DNA-damage-inducible transcript 4
|
10369290
|
Sesn2
|
4.77E-08
|
2.452913
|
sestrin 2
|
10516932
|
Txnip
|
0.000209
|
1.636378
|
thioredoxin interacting protein
|
10494428
|
Atf3
|
9.52E-10
|
4.190948
|
activating transcription factor 3
|
10361091
|
Slc3a2
|
2.1E-08
|
1.642015
|
solute carrier family 3 (activators of dibasic and neutral amino acid transport), member 2
|
10465772
|
Trib3
|
1.19E-07
|
2.416594
|
tribbles pseudokinase 3
|
10488608
|
Cebpg
|
9.01E-09
|
1.68513
|
CCAAT/enhancer binding protein (C/EBP), gamma
|
10562416
|
Rela
|
1.23E-09
|
2.837673
|
v-rel reticuloendotheliosis viral oncogene homolog A (avian)
|
10460631
|
Hmox1
|
2.71E-09
|
2.970025
|
heme oxygenase 1
|
10572897
|
Hspb1
|
1.13E-08
|
3.11411
|
heat shock protein 1
|
10408928
|
Nfe2l2
|
1.08E-07
|
1.690716
|
nuclear factor, erythroid derived 2, like 2
|
10483809
|
Map3k5
|
1.93E-08
|
2.27558
|
mitogen-activated protein kinase kinase kinase 5
|
10361926
|
Slc2a1
|
6.37E-06
|
2.168648
|
solute carrier family 2 (facilitated glucose transporter), member 1
|
10507594
|
Capg
|
5.84E-08
|
1.852655
|
capping protein (actin filament), gelsolin-like
|
10539135
|
Gclc
|
2.11E-09
|
4.284143
|
glutamate-cysteine ligase, catalytic subunit
|
10587266
|
Sqstm1
|
3.86E-07
|
2.771646
|
sequestosome 1
|
10385572
|
Cd44
|
9.79E-12
|
3.501365
|
CD44 antigen
|
10485405
|
Jun
|
1.26E-06
|
1.687334
|
jun proto-oncogene
|
10514466
|
Plin2
|
6.4E-09
|
3.393173
|
perilipin 2
|
10514221
|
Gch1
|
8.05E-06
|
1.573587
|
GTP cyclohydrolase 1
|
10419288
|
Pgd
|
3.29E-05
|
1.63238
|
phosphogluconate dehydrogenase
|
10518570
|
Acsl4
|
3.84E-09
|
1.527963
|
acyl-CoA synthetase long-chain family member 4
|
10607089
|
Nras
|
9.04E-09
|
1.766424
|
neuroblastoma ras oncogene
|
10494857
|
Kras
|
3.63E-09
|
2.608895
|
Kirsten rat sarcoma viral oncogene homolog
|
10549256
|
Slc38a1
|
2.56E-08
|
3.663981
|
solute carrier family 38, member 1
|
10431874
|
Got1
|
4.71E-09
|
2.403565
|
glutamic-oxaloacetic transaminase 1, soluble
|
10467842
|
Map1lc3a
|
2.41E-06
|
1.708451
|
microtubule-associated protein 1 light chain 3 alpha
|
10477637
|
Wipi2
|
1.3E-08
|
1.907656
|
WD repeat domain, phosphoinositide interacting 2
|
10527133
|
Sat1
|
2.07E-11
|
3.020738
|
spermidine/spermine N1-acetyl transferase 1
|
10607467
|
Egfr
|
3.31E-10
|
3.350486
|
epidermal growth factor receptor
|
10374366
|
Prkaa1
|
4.21E-08
|
1.917747
|
protein kinase, AMP-activated, alpha 1 catalytic subunit
|
10422707
|
Ano6
|
4.42E-10
|
2.274626
|
anoctamin 6
|
10426479
|
Bnip3
|
2.44E-06
|
-1.55474
|
BCL2/adenovirus E1B interacting protein 3
|
10414269
|
TABLE 2 The ferroptosis differentially expressed genes were divided into three parts
Suppressor
|
Diver
|
Marker
|
Gclc, Sqstm1, Cd44, Jun, Plin2, Gch1
|
Pgd, Acsl4, Nras, Kras, Slc38a1, Got1, Map1lc3a, Wipi2, Sat1, Egfr, Prkaa1, Ano6
|
Dusp1, Txnrd1, Srxn1, Chac1, Slc7a11, Ddit4, Sesn2, Txnip, Atf3, Slc3a2, Trib3, Cebpg, Rela, Hmox1, Hspb1, Nfe2l2, Map3k5, Slc2a1, Capg, Bnip3
|
Functional Enrichment and Pathway Analysis of the Ferroptosis DEGs
First, the online software DAVID was used to detect functional enrichment and pathway analysis to further clarify the functions of the DEGs in acute pancreatitis. Functional enrichment analysis of GO terms contains BP, CC and MF three categories. The P-value was indicated by the color of bubbles, and the size of bubbles, which had a significant positive relationship with the number of DEGs engaged in this term, indicated the number of DEGs contained in the term (Figure 2). Cellular response to hydrogen peroxide, oxidative stress, apoptotic process, negative regulation of the apoptotic process, positive regulation of the apoptotic process, and so on were among the GO terms in the BP category. The GO terms in the CC category were mainly enriched in the cytosol, cytoplasm, macromolecular complex, etc. The DEGs were mostly enriched in MF terms such as identical protein binding, protein homodimerization activity, protein kinase binding, and ubiquitin protein ligase binding. The KEGG pathway analysis was conducted, containing MAPK signaling pathway, autophagy, ferroptosis pathway and fluid shear stress and atherosclerosis and so on. Second, we submitted the related DEGs to Metascape. The biological process was considerably enriched in response to oxidative stress, cellular response to famine, and positive control of cell death, according to the results of the enrichment pathway and analysis. The MAPK signaling pathway, ferroptosis, oxidative stress and redox pathway, and oxidative stress response were all significantly activated in biological pathways (Figure 3). Finally, the MAPK signaling pathway was identified as the most important biological pathway involved in both DAVID and Metascape analyses.
Protein-Protein Interaction Network Construction of DEGs
To further invested in the potential relationships between DEGs, we uploaded them to STRING online database. Finally, a PPI network of the associated DEGs was created, with 35 nodes and 123 edges with pairs combined score >0.4 (Figure 4). The genes are represented by the nodes in the network, while the edges reflect the relationships between them. MCODE, a Cytoscape program, was utilized to select the submodule of significance, and the result showed a submodule score of 6.9, containing 12 nodes and 38 edges. Subsequently, we also calculated the degree of those nodes. In this study, we selected 8 nodes with degree ≥10 as criteria, including Jun (degree=15); Sqstm1, Kras, Nfe2l2 and Hmox1 (degree=14); Slc7a11 (degree=12); Egfr (degree=11); Atf3 (degree=10). Except for Jun, 7 of the genes were contained in the submodule and they were all up-regulated in AP samples. We identified these 7 genes as hub genes. Additionally, the hub genes were uploaded to Metascape for functional analysis, and these hub genes were shown to be primarily involved in oxidative stress response, oxidative stress response, and oxidative stress response, according to the results (Figure 5).
Construction of Gene-Related miRNA pairs
The database ENCORI predicted a total of 19619 targets in 6 databases (Figure 6). The DEG genes of GSE109227 and Ferroptosis Database were integrated with the targeted genes, and 26 miRNA-mRNA pairs were identified. There were 7 mRNAs of miR-148b-3p, 15 mRNAs of miR-22-3p, 1 mRNA of miR-29a-3p, and 3 mRNAs of miR-135a-5p.
LncRNA-miRNA-mRNA Network Analysis
We used the ENCORI database to identify the potential lncRNAs of the selected miRNAs, and 208 lncRNA-miRNA pairs were obtained. The lncRNA-miRNA-mRNA network was shown in Figure 7, which contained 145 lncRNA nodes, 4 miRNA nodes, 18 mRNA nodes and 235 edges.
Transcriptional Factor Regulation Network Analysis of Hub Genes
To determine how hub genes are transcribed and how transcription factors affect their expression, we used Networkanalyst to build a gene-TFs regulation network (Figure 8). The network includes 27 TFs, in addition to the hub genes, for a total of 73 gene-TF interaction pairings. The regulation network of gene-TFs shows that transcriptional regulators were substantially enriched in the majority of the hub genes. We considered MYC to be the key TF that regulates the majority of the hub genes: Atf3, Hmox1, Sqstm1 and Nfe2l2. Other TFs like UBTF, NRF1, CDH1, ETS1, JUND and HCFC1 were likewise thought to be a key TF in the regulation among most hub genes.
Hub Genes and Core TFs Correlation Analysis
As a result of the finding that MYC has a critical regulatory relationship with seven hub genes, we used GEPIA to look for hub genes and projected core TFs correlation. The result of the correlation analysis between MYC and hub genes: SQSTM1, KRAS, NFE2L2, HMOX1, SLC7A11, EGFR and ATF3 are shown in Figure 9. The non-log-scale axis was utilized for calculation, and the log-scale axis was used for visualization. We finally identified positive correlations of MYC and hub genes with criteria of P value less than 0.05.