Yang Mei, Gu Yu-Yu, Peng Hua, Zhao Mei, Wang Jia, Huang Sheng-Kai, Yuan Xing-Hua, Li Jia, Sang Jian-Li, Luo Qing, Huang Changzhi
Department of Etiology and Carcinogenesis and State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 17 Panjiayuan Nanli, Chaoyang District, Beijing, 100021, People's Republic of China.
J Cancer Res Clin Oncol. 2015 Jun;141(6):1037-47. doi: 10.1007/s00432-014-1865-2. Epub 2014 Nov 29.
Nuclear apoptosis-inducing factor 1 (NAIF1) could induce apoptosis in gastric cancer cells. Previously, we have reported that the expression of NAIF1 protein is down-regulated in gastric cancer tissues compared with the adjacent normal tissues. However, the role of NAIF1 in gastric cancer cells is not fully understood.
The effects of NAIF1 on cell viability were evaluated by MTT and colony formation assays. The ability of cellular migration and invasion were analyzed by transwell assays. The expression levels of targeted proteins were determined by western blot. The relative RNA expression levels were analyzed using quantitative polymerase chain reaction assays. Xenograft experiment was employed to determine the anti-tumor ability of NAIF1 in vivo.
The study demonstrates that transient transfection of NAIF1 in gastric cancer cells BGC823 and MKN45 could inhibit the cell proliferation, migration, and invasion of the two gastric cancer cell lines. The tumor size is smaller in NAIF1-overexpressed MKN45 cell xenograft mice than in unexpressed group. Further in-depth analysis reveals that NAIF1 reduces the expression of MMP2 as well as MMP9, and inhibits the activation of FAK, all of which are key molecules involved in regulating cell migration and invasion. In addition, NAIF1 inhibits the expression of c-Jun N-terminal kinase (JNK) by accelerating its degradation through ubiquitin-proteasome pathway. Meanwhile, NAIF1 reduces the mRNA and protein expression of ERK1/2.
Our study revealed that NAIF1 plays a role in regulating cellular migration and invasion through the MAPK pathways. It could be a therapeutic target for gastric cancer.
核凋亡诱导因子1（NAIF1）可诱导胃癌细胞凋亡。此前，我们报道过与相邻正常组织相比，NAIF1蛋白在胃癌组织中的表达下调。然而，NAIF1在胃癌细胞中的作用尚未完全明确。
通过MTT和集落形成实验评估NAIF1对细胞活力的影响。采用Transwell实验分析细胞迁移和侵袭能力。通过蛋白质印迹法测定靶向蛋白的表达水平。使用定量聚合酶链反应实验分析相对RNA表达水平。采用异种移植实验确定NAIF1在体内的抗肿瘤能力。
该研究表明，在胃癌细胞BGC823和MKN45中瞬时转染NAIF1可抑制这两种胃癌细胞系的增殖、迁移和侵袭。NAIF1过表达的MKN45细胞异种移植小鼠的肿瘤大小比未表达组小。进一步深入分析发现，NAIF1降低MMP2和MMP9的表达，并抑制FAK的激活，所有这些都是参与调节细胞迁移和侵袭的关键分子。此外，NAIF1通过泛素-蛋白酶体途径加速c-Jun氨基末端激酶（JNK）的降解，从而抑制其表达。同时，NAIF1降低ERK1/2的mRNA和蛋白表达。
我们的研究表明，NAIF1通过丝裂原活化蛋白激酶（MAPK）途径在调节细胞迁移和侵袭中发挥作用。它可能是胃癌的一个治疗靶点。
