探讨免疫球蛋白超级家族成员9促进肺腺癌细胞增殖的作用及机制

肺癌是全球发病率与死亡率均位于第一位的恶性肿瘤。肺腺癌(lung adenocarcinoma,LUAD)大约占整个肺癌的40%。但是,目前对肺腺癌发生发展的机制尚未阐明。TCGA在线数据库GEPIA证实,免疫球蛋白超级家族成员9(immunoglobulin superfamily member 9,IGSF9)在肺腺癌中的平均表达量是6.56,其在正常癌旁组织中的平均表达量是0.55,提示IGSF9在肺腺癌中的表达量是正常癌旁组织的11.93倍。人类蛋白组学数据库也提示,IGSF9在肺腺癌中高表达。通过qRT-PCR检测IGSF9在肺腺癌细胞中的表达量,发现其在A549和H1299细胞中的表达量分别是其在BEAS-2B细胞中的4.17倍和6.6倍。细胞功能实验发现,过表达IGSF9,其LUAD细胞的增殖能力显著增加。平板克隆形成实验发现,在A549细胞中,对照组平板克隆大约有240个,过表达IGSF9后,该组细胞的平板克隆数大约是385个,实验组的克隆数目是对照组的1.60倍(P<0.01)。敲低IGSF9,则LUAD细胞增殖能力明显降低。平板克隆形成实验发现,在H1299细胞中,对照组平板克隆大约有320个,敲低IGSF9后,该组细胞的平板克隆数大约是164个,实验组的克隆数目仅为对照组的51.25%(P<0.01)。生物信息学预测结合后期研究证实,IGSF9可显著抑制叉头蛋白K2(forkhead box protein K2,FOXK2)的表达。MTS实验发现,过表达FOXK2可显著逆转IGSF9对LUAD细胞增殖的促进作用,而敲低FOXK2则可明显补偿敲低IGSF9对LUAD细胞的增殖抑制作用。这些结果提示,IGSF9通过下调FOXK2从而促进LUAD细胞的增殖。

Mechanistic Studies of How IGSF9 Promotes Proliferation of Lung Adenocarcinoma Cells

Lung cancer is a malignant tumor of the highest morbidity and mortality in the world.Lung adenocarcinoma(LUAD),whose development mechanism is unclear,accounts for about 40%lung cancer.Briefly,we found immunoglobulin superfamily member 9(IGSF9)was enhanced in LUAD through GEPIA and The Human Protein Atlas.qRT-PCR assays demonstrated that the expression of IGSF9 were 4.17-fold and 6.6-fold in A549 and H1299 cells,compared with that in BEAS-2B cell.MTS assays suggested that restored IGSF9 could remarkably enhance the proliferation of LUAD cells,while knocking down IGSF9 did the opposite.Compared with the control group,IGSF9 accelerated the colonyforming ability of A549 to 1.60 fold.While knocking down IGSF9,the colony-forming ability of H1299 cells were significantly decreased as 51.25%compared to the control group.Bioinformatics analysis combined with experiments showed that IGSF9 evidently downregulated forkhead box protein K2(FOXK2).From MTS assays,we found that overexpressing FOXK2 markedly inhibited IGSF9 and LUAD cells proliferation,while decreasing FOXK2 could reverse the effect of knocking down IGSF9 on LUAD cells.Collectively,these results showed that IGSF9 accelerated LUAD cells proliferation via downregulating FOXK2.