Kinesin Family Member 18A (KIF18A) Contributes to the Proliferation, Migration, and Invasion of Lung Adenocarcinoma Cells In Vitro and In Vivo

Abstract

Objective: To determine the expression levels of KIF18A in lung adenocarcinoma and its relationship with the clinicopathologic features of patients undergoing radical colectomy and explore the potential role in the progression of lung adenocarcinoma.

Methods: Immunohistochemical assays were performed to explore the expression levels of KIF18A in 82 samples of lung adenocarcinoma and corresponding normal tissues. According to the levels of KIF18A expression in lung adenocarcinoma tissue samples, patients were classified into the KIF18A high expression group and low expression group. Clinical data related to the perioperative clinical features (age, gender, smoking, tumor size, differentiation, clinical stage, and lymph node metastasis), the potential correlation between KIF18A expression levels, and clinical features were analyzed, and the effects of KIF18A on lung adenocarcinoma cell proliferation, migration, and invasion were measured by colony formation assay, MTT assay, wound healing assay, and transwell assays. The possible effects of KIF18A on tumor growth and metastasis were measured in mice through tumor growth and tumor metastasis assays in vivo.

Results: KIF18A in lung adenocarcinoma tissues. Further, KIF18A was significantly associated to clinical characteristic features including the tumor size (P = 0.033) and clinical stage (P = 0.041) of patients with lung adenocarcinoma. Our data also investigated that KIF18A depletion dramatically impairs the proliferation, migration, and invasion capacity of lung adenocarcinoma cells in vitro and inhibits tumor growth and metastasis in mice.

Conclusions: Our study reveals the involvement of KIF18A in the progression and metastasis of lung adenocarcinoma and provides a novel therapeutic target for the treatment of lung adenocarcinoma.

Figure 1

KIF18A has high expression in human lung adenocarcinoma tissues. (a) Shown above is the mRNA expression level of KIF18A in cancer and normal tissues in the GEPIA (LUAD: lung adenocarcinoma). Shown below is the disease survival time of low and high mRNA expression of KIF18A in the 483 cases of lung adenocarcinoma in the GEPIA. (b) Immunohistochemical assays were performed, and the representative photographs of KIF18A expression levels in human lung adenocarcinoma tissues were exhibited (×100 and ×200 magnifications, respectively). (c) IHC staining results revealed the expression levels of KIF18A in the adjacent nontumor tissues (×100 and ×200 magnifications, respectively).

Figure 2

KIF18A expression was effectively blocked in both A549 and H1975 human lung adenocarcinoma cells caused by its shRNA plasmids. (a) Quantitative PCR assays revealed the dramatically reduced expression levels of KIF18A caused by its shRNA in both A549 and H1975 cells, respectively. (b) Immunoblot assays confirmed the efficient silencing of KIF18A caused by its shRNA plasmids in A549 and H1975 cells. Results are presented as the mean ± SD; ^∗P < 0.05.

Figure 3

KIF18A promotes the proliferation, migration and invasion of lung adenocarcinoma cells in vitro. (a) A549 and H1975 cells transfected with control or KIF18A shRNA, and the proliferation capacity was quantified by colony number through colony formation assays. (b) The OD value generated by MTT assays showed the inhibition of cell proliferation caused by KIF18A ablation. (c) KIF18A depletion resulted in the lower migration degree in A549 and H1975 cells. Photographs showed that at 0- and 24-hour time points, migrated cells were present. (d) Transwell assays using both A549 and H1975 human lung adenocarcinoma cells transfected with control or KIF18A shRNA plasmids, and the degree of invasion was quantified by the invasion cell number. Results are presented as the mean ± SD; ^∗P < 0.05.

Figure 4

KIF18A contributes to lung adenocarcinoma growth and metastasis in mice. (a) A549 cells infected with control or KIF18A shRNA lentivirus were subcutaneously implanted into nude mice. After 2 weeks, tumors were isolated, and volume was examined every 3 days. (n = 6 in each group). Tumor growth curve was calculated and analyzed according to the average volume of 6 tumors in each group. (b) Lung metastasis assays were performed, and the representative photographs of the lung in control or KIF18A shRNA lentivirus-infected groups were shown. (c) IHC assays indicated the expression levels of KIF18A in control or KIF18A depletion tumor tissues isolated from mice. Results are presented as the mean ± SD; ^∗P < 0.05.