Expression, Clinical Significance, Immune Infiltration, and Regulation Network of miR-3940-5p in Lung Adenocarcinoma Based on Bioinformatic Analysis and Experimental Validation

Abstract

Background: Based on bioinformatics analysis and experimental validation, we investigated the expression, clinical significance, immune infiltration, and potential signaling pathways of miR-3940-5p in lung adenocarcinoma (LUAD).

Methods: 521 LUAD tissue samples and 46 normal lung tissue samples from The Cancer Genome Atlas (TCGA) database. We evaluated the relationship between clinical features and miR-3940-5p expression using Kruskal-Wallis, Wilcoxon sign-rank, and logistic regression, explored the relationship between miR-3940-5p expression and the prognosis of LUAD patients using Kaplan-Meier survival curve analysis. Several databases were used to identify miRNA targets. MiR-3940-5p target genes were analyzed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The significant role of miR-3940-5p in function was evaluated using immune infiltration analysis. LUAD cell lines were tested for miR-3940-5p expression using QRT-PCR.

Results: There was a significant association between high miR-3940-5p expression in LUAD and T stage (P=0.005), pathologic stage (P=0.047), race (White vs Asian & Black or African American) (P=0.041), residual tumor (P=0.043), and anatomic neoplasm subdivision2 (P=0.030). MiR-3940-5p expression predicted poor overall survival (HR: 1.35; 95% CI: 1.01-1.81; P=0.045), disease-specific survival (HR: 1.53; 95% CI: 1.05-2.23; P=0.026), and progression-free survival (HR: 1.35; 95% CI: 1.03-1.77; P=0.032). BAP1, BBS1, CCR2, KCNE3, PEBP1, and RABL2A were all associated with poor OS in LUAD patients with low miR-3940-5p expression levels. According to GO and KEGG analyses, miR-3940-5p may play a role in LUAD development by regulating pathways such as measles, PI3K-Akt signaling pathway, and p53 signaling pathway. There was a correlation between the expression level of miR-3940-5p and immune infiltration. LUAD cell lines showed significantly higher levels of miR-3940-5p than Beas-2B cells.

Conclusion: A high expression of miR-3940-5p is significantly associated with a poor prognosis in patients with LUAD, suggesting that it could be used as a prognostic biomarker.

Keywords: clinical significance; immune infiltration; lung adenocarcinoma; microRNA-3940-5p; regulation network.

Figure 1

Expression of miR-3940-5p in LUAD and normal tissues. (A) MiR-3940-5p expression was significantly higher in 521 LUAD tissues (0.631±0.028) compared with 46 normal tissues (0.393±0.128) (***P<0.001). (B) MiR-3940-5p expression was significantly higher in 46 LUAD tissues (0.586 ± 0.085) compared with 46 normal tissues (0.393 ± 0.128) (*P < 0.05). (C) ROC curve.

Figure 2

Association with miR-3940-5p and clinical characteristics in LUAD. (A) T Stage, (B) Pathologic stage, (C) Residual tumor, (D) Anatomic neoplasm subdivision 2. **P<0.01; ***P<0.001.

Figure 3

Relationship between miR-3940-5p expression and prognosis. (A) Overall survival, OS, (B) Disease specific survival, DSS, (C) Progress free interval, PFS.

Figure 4

Venn diagram of common genes between target genes of miR-3940-5p and LUAD down regulated genes.

Figure 5

Relationship between expression of miR-3940-5p target genes and prognosis. (A) BAP1, (B) BBS1, (C) CCR2, (D) KCNE3, (E) PEBP1, (F) RABL2A. Overall survival, OS.

Figure 6

GO analysis of miR-3940-5p target genes.

Figure 7

KEGG analysis of miR-3940-5p target genes.

Figure 8

The expression level of miR-3940-5p was related to the immune infiltration in the tumor microenvironment (group comparison chart). Ns, P>0.05; *P<0.05, **P<0.01; ***P<0.001.

Figure 9

The expression level of miR-3940-5p was related to the immune infiltration in the tumor microenvironment (lollipop chart).

Figure 10

Expression of miR-3940-5p in A549, PC9, and Beas-2B. *P<0.05.