CEACAM5 stimulates the progression of non-small-cell lung cancer by promoting cell proliferation and migration

Abstract

Objective: To detect the expression of CEA-related cell adhesion molecule 5 (CEACAM5) in non-small-cell lung cancer (NSCLC) and explore its function in the progression and development of NSCLC.

Methods: qRT-PCR and immunohistochemistry were performed to detect CEACAM5 expression in human NSCLC tissues and cell lines. The correlation between CEACAM5 expression and the clinicopathological features of patients with NSCLC was also investigated. MTT, colony formation, wound healing, and immunoblot assays were performed to detect the functions of CEACAM5 in NSCLC cells in vitro, and immunoblotting was used to detect the effects of CEACAM5 on p38-Smad2/3 signaling.

Results: CEACAM5 expression was elevated in human NSCLC tissues and cells. We further found that CEACAM expression was correlated with clinicopathological features including T division, lymph invasion, and histological grade in patients with NSCLC. The in vitro assays confirmed that CEACAM5 depletion inhibited the proliferation and migration of NSCLC cells by activating p38-Smad2/3 signaling. We verified the involvement of CEACAM5 in the suppression of NSCLC tumor growth in mice.

Conclusion: CEACAM5 stimulated the progression of NSCLC by promoting cell proliferation and migration in vitro and in vivo. CEACAM5 may serve as a potential therapeutic target for the treatment of NSCLC.

Keywords: CEA-related cell adhesion molecule 5; Non-small-cell lung cancer; migration; p38–Smad2/3 signaling; proliferation; therapeutic target; tumorigenesis.

Figure 1.

CEA-related cell adhesion molecule 5 (CEACAM5) expression was enhanced in human non-small-cell lung cancer (NSCLC) tissues and cells. (a) Bioinformatic analysis revealed enhanced CEACAM5 expression in patients with NSCLC compared with that in normal tissues according to The Cancer Gene Atlas database. (b) qRT-PCR assays depicted the mRNA levels of CEACAM5 in 87 pairs of NSCLC tissues and corresponding normal tissues (c) Immunohistochemical assays revealing higher CEACAM5 expression in NSCLC tissues than in the corresponding normal tissues. Representative photograph are presented (×100 and ×200 magnification, respectively). (d) qRT-PCR and (e) immunoblot assays revealed the expression of CEACAM5 in HBE, H1299, H358, HCC827, and A549 cells.

Figure 2.

CEA-related cell adhesion molecule 5 (CEACAM5) expression was downregulated in A549 and HCC827 cells after CEACAM5 shRNA transfection. qRT-PCR (a) and immunoblot analyses (b) revealed the decrease in CEACAM5 levels in A549 and HCC827 cells transfected with CEACAM5 shRNA plasmids. β-actin was used as an internal control. *P < 0.05.

Figure 3.

CEA-related cell adhesion molecule 5 (CEACAM5) promoted the proliferation and migration of non-small-cell lung cancer cells in vitro. (a) Colony formation assays revealed the inhibitory effect of CEACAM5 ablation on cell proliferation. (b) Wound healing assays were conducted to evaluate cell migration using A549 and HCC827 cells transfected with control or CEACAM5 shRNA plasmids. Representative photographs are presented. (c) Immunoblot assays revealed the reduced expression of PCNA and Ki67 in A549 and HCC827 cells after CEACAM5 ablation. (d) Immunoblot assays indicated the decreased expression of MMP2 and MMP9 in A549 and HCC827 cells following CEACAM5 ablation. Results are presented as the mean ± SEM, *P < 0.05, **P < 0.01.

Figure 4.

CEA-related cell adhesion molecule 5 (CEACAM5) promoted the proliferation and migration of non-small-cell lung cancer cells via TGF-β signaling. (a) Immunoblot assays revealed the levels of p38 and Smad3 and the phosphorylation status of p38 and Smad2/3 in A549 cells transfected with control or CEACAM5 shRNA plasmids and stimulated in the presence of 1 ng/mL TGF-β for 2 hours. (b) Immunoblot assays indicated the levels of MMP2 and PCNA and the phosphorylation of p38 in A549 cells transfected with CEACAM5 shRNA plasmids or both CEACAM5 shRNA and pcDNA3.1-p38 plasmids. Results are presented as the mean ± SEM, *P < 0.05, **P < 0.01.

Figure 5.

CEA-related cell adhesion molecule 5 (CEACAM5) depletion impaired non-small-cell lung cancer tumor growth in vivo. (a) A549 cells infected with CEACAM5 or control shRNA lentivirus were implanted into nude mice. The tumor volume was monitored every week from the third week. After 49 days, tumors were isolated (n = 6 for each group). Representative images of tumors are presented (left), and tumor growth curves and mouse weight were calculated (right). (b) Immunohistochemical assays revealed the expression of CEACAM5 in control or CEACAM5-depleted tumor tissues. (c) Immunoblot assays further confirmed the expression of CEACAM5, MMP2, and PCNA and the phosphorylation of p38 and SMAD2/3 in tumor tissues from control or CEACAM5-depleted mice. Results are presented as the mean ± SEM, *P < 0.05, **P < 0.01.