FKBP4 Accelerates Malignant Progression of Non-Small-Cell Lung Cancer by Activating the Akt/mTOR Signaling Pathway

Abstract

Objective: To study the expression, biological function, and mechanism of FKBP4 in non-small-cell lung cancer (NSCLC).

Methods: First of all, the expression of FKBP4 in NSCLC tissues and cell lines was detected by qRT-PCR; then, the effects of FKBP4 on proliferation, apoptosis, migration, and invasion of NSCLC were studied by CCK-8 assays, flow cytometry assays, wound-healing assays, and Transwell assays. After that, tumor xenografts were used to explore the effect of FKBP4 on NSCLC tumor growth in vivo, and the phosphorylation of Akt and mTOR was measured by western blot.

Results: FKBP4 was highly expressed in NSCLC tissues and cells, and its expression was closely related to NSCLC tumor size, lymph node metastasis, and patient prognosis. In vitro, FKBP4 can promote NSCLC cell proliferation, migration, and invasion and inhibit NSCLC cell apoptosis. In vivo, FKBP4 can promote NSCLC tumor growth. Furthermore, FKBP4 can promote Akt and mTOR phosphorylation and activate the Akt/mTOR signaling pathway and an mTOR inhibitor can neutralize the functions of FKBP4 in NSCLC cells.

Conclusion: FKBP4 serves as an oncogene to promote malignant processes in NSCLC, and it has the potential to be used as a biological marker and therapeutic target for NSCLC.

Figure 1

Bioinformatics analysis of FKBP4 expression in NSCLC: (a) expression analysis of FKBP4 in large cell lung cancer; (b) expression analysis of the FKBP4 gene in squamous cell lung cancer; (c) expression analysis of FKBP4 lung adenocarcinoma (N = 640, Welch's t-test, P = 4.702e − 59).

Figure 2

FKBP4 expression in NSCLC tissues and cells: (a) FKBP4 expression in NSCLC tissues, N = 40; (b) FKBP4 expression in NSCLC tissues; data were compared using ANOVA followed by the Dunnett t-test, N = 3; ^∗P < 0.05 vs. normal or HBE.

Figure 3

Survival analysis of patients with high and low FKBP4 expression groups; log-rank test, N = 40, P < 0.001.

Figure 4

FKBP4 overexpression and silencing verification: (a) FKBP4 mRNA expression changes detected by qRT-PCR; (b) FKBP4 protein expression changes detected by western blot; N = 3, ^∗P < 0.05.

Figure 5

FKBP4 promotes the proliferation of NSCLC cells: cell proliferation after FKBP4 was overexpressed in PC-9 cells (a) or FKBP4 was silenced in A549 cells (b); N = 3, ^∗P < 0.05.

Figure 6

FKBP4 inhibits apoptosis of NSCLC cells: apoptosis of cells after overexpression of FKBP4 (a) in PC-9 cells and silencing of FKBP4 (b) in A549 cells; N = 3, ^∗P < 0.05.

Figure 7

FKBP4 promotes NSCLC cell migration: cell migration after overexpression of FKBP4 (a) in PC-9 cells and silencing of FKBP4 (b) in A549 cells; N = 3, ^∗P < 0.05.

Figure 8

FKBP4 promotes NSCLC cell invasion: cell invasion after overexpression of FKBP4 (a) in PC-9 cells and silence of FKBP4 (b) in A549 cells; N = 3, ^∗P < 0.05.

Figure 9

FKBP4 promotes NSCLC growth in vivo; N = 3, ^∗P < 0.05.

Figure 10

FKBP4 activates the Akt/mTOR signaling pathway in NSCLC cells; N = 3, ^∗P < 0.05.

Figure 11

mTOR inhibitor neutralizes the functions of FKBP4 in NSCLC cells. The PC-9 cells transfected with FKBP4 overexpression plasmids were treated with mTOR inhibitor rapamycin (200 nmol/l). Cell proliferation, apoptosis, migration, and invasion were analyzed by the CCK8 assay (a), flow cytometry (b), scratch test (c), and Transwell experiment (d), respectively; N = 3, ^∗P < 0.05.