Department of Oncology, The First Clinical College, Dalian Medical University, Dalian, 116044, People's Republic of China.
Department of Oncology, The First Affiliated Hospital of Dalian Medical University, Dalian, 116011, People's Republic of China.
Int J Biochem Cell Biol. 2020 Jun;123:105750. doi: 10.1016/j.biocel.2020.105750. Epub 2020 Apr 20.
Cell adhesion molecule 4 (CADM4) is downregulated in many human cancers. However, CADM4 expression levels in human non-small cell lung cancer (NSCLC) tissues and its roles in NSCLC progression remain unknown. Our study aims to address these issues. We examined CADM4 levels in NSCLC tissues using real-time PCR and western blot. A549 and NCI-H1299 cells were then transfected with pcDNA3.1-CADM4 plasmid or siCADM4 to overexpress or knock down CADM4. Cell proliferation, cell cycle distribution, migration, and invasion were evaluated. NSCLC cells transfected with pcDNA3.1-CADM4 plasmid or siCADM4 were treated with SC79 or LY294002, respectively, to investigate the involvement of the Akt signaling pathway. Male nude mice were subcutaneously injected with stably transfected cells (1 × 10 cells/mice) to observe tumor growth. Stable transfectants were injected into nude mice (1 × 10 cells/mice) via tail vein to observe tumor metastasis. The results showed that CADM4 gene and protein levels in NSCLC tissues were significantly lower than those in corresponding adjacent tissues. CADM4 overexpression markedly inhibited cell proliferation, migration, and invasion. We also found that matrix metalloproteinase 9 (MMP-9) and MMP-2 activities were reduced. Moreover, CADM4 overexpression arrested the cell cycle at G1 phase, with the changes in expression of cell cycle regulators. The Akt signaling pathway was inhibited by CADM4 overexpression. In contrast, CADM4 knockdown showed the opposite effects. Additionally, SC79 and LY294002 reversed the effects of CADM4 overexpression and CADM4 knockdown in vitro, respectively. In xenograft models, CAMD4 overexpression suppressed, while CADM4 knockdown promoted tumor growth, accompanied by changes in Ki67 expression. In in vivo metastasis assay, CADM4 overexpression decreased, while CADM4 knockdown increased numbers of metastatic nodules in lung and liver. These evidences suggest that CADM4 may regulate NSCLC progression via the Akt signaling pathway. CADM4 may be a potential therapeutic target for NSCLC.
细胞黏附分子 4（CADM4）在许多人类癌症中表达下调。然而，CADM4 在人类非小细胞肺癌（NSCLC）组织中的表达水平及其在 NSCLC 进展中的作用尚不清楚。我们的研究旨在解决这些问题。我们使用实时 PCR 和 Western blot 检测 NSCLC 组织中的 CADM4 水平。然后，使用 pcDNA3.1-CADM4 质粒或 siCADM4 转染 A549 和 NCI-H1299 细胞以过表达或敲低 CADM4。评估细胞增殖、细胞周期分布、迁移和侵袭。用 SC79 或 LY294002 分别处理转染 pcDNA3.1-CADM4 质粒或 siCADM4 的 NSCLC 细胞，以研究 Akt 信号通路的参与情况。将稳定转染的细胞（1×10 个细胞/只）皮下注射入雄性裸鼠以观察肿瘤生长。将稳定转染的细胞通过尾静脉注射入裸鼠（1×10 个细胞/只）以观察肿瘤转移。结果显示，CADM4 基因和蛋白在 NSCLC 组织中的水平明显低于相应的相邻组织。CADM4 过表达显著抑制细胞增殖、迁移和侵袭。我们还发现基质金属蛋白酶 9（MMP-9）和 MMP-2 的活性降低。此外，CADM4 过表达使细胞周期在 G1 期停滞，细胞周期调节剂的表达发生变化。CADM4 过表达抑制 Akt 信号通路。相反，CADM4 敲低则表现出相反的效果。此外，SC79 和 LY294002 分别逆转了 CADM4 过表达和 CADM4 敲低在体外的作用。在异种移植模型中，CADM4 过表达抑制，而 CADM4 敲低促进肿瘤生长，伴随 Ki67 表达的变化。在体内转移实验中，CADM4 过表达减少，而 CADM4 敲低增加肺和肝中的转移结节数量。这些证据表明，CADM4 可能通过 Akt 信号通路调节 NSCLC 的进展。CADM4 可能是 NSCLC 的潜在治疗靶点。
