Department of Tissue Engineering and Regeneration, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China.
Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Shandong, China.
PLoS Genet. 2021 Feb 4;17(2):e1009283. doi: 10.1371/journal.pgen.1009283. eCollection 2021 Feb.
Activating transcription factor 3 (ATF3) is a key transcription factor involved in regulating cellular stress responses, with different expression levels and functions in different tissues. ATF3 has also been shown to play crucial roles in regulating tumor development and progression, however its potential role in oral squamous cell carcinomas has not been fully explored. In this study, we examined biopsies of tongue squamous cell carcinomas (TSCCs) and found that the nuclear expression level of ATF3 correlated negatively with the differentiation status of TSCCs, which was validated by analysis of the ATGC database. By using gain- or loss- of function analyses of ATF3 in four different TSCC cell lines, we demonstrated that ATF3 negatively regulates the growth and migration of human TSCC cells in vitro. RNA-seq analysis identified two new downstream targets of ATF3, interferon alpha inducible proteins 6 (IFI6) and 27 (IFI27), which were upregulated in ATF3-deleted cells and were downregulated in ATF3-overexpressing cells. Chromatin immunoprecipitation assays showed that ATF3 binds the promoter regions of the IFI6 and IFI27 genes. Both IFI6 and IFI27 were highly expressed in TSCC biopsies and knockdown of either IFI6 or IFI27 in TSCC cells blocked the cell growth and migration induced by the deletion of ATF3. Conversely, overexpression of either IFI6 or IFI27 counteracted the inhibition of TSCC cell growth and migration induced by the overexpression of ATF3. Finally, an in vivo study in mice confirmed those in vitro findings. Our study suggests that ATF3 plays an anti-tumor function in TSCCs through the negative regulation of its downstream targets, IFI6 and IFI27.
激活转录因子 3（ATF3）是一种关键的转录因子，参与调节细胞应激反应，在不同组织中具有不同的表达水平和功能。ATF3 还被证明在调节肿瘤的发生和发展中发挥着关键作用，但其在口腔鳞状细胞癌中的潜在作用尚未得到充分探索。在本研究中，我们检查了舌鳞状细胞癌（TSCC）的活检组织，发现 ATF3 的核表达水平与 TSCC 的分化状态呈负相关，这一结果通过对 ATGC 数据库的分析得到了验证。通过在四种不同的 TSCC 细胞系中对 ATF3 的功能增益或缺失分析，我们证明了 ATF3 负调节人 TSCC 细胞在体外的生长和迁移。RNA-seq 分析鉴定了 ATF3 的两个新的下游靶标，干扰素诱导蛋白 6（IFI6）和 27（IFI27），它们在 ATF3 缺失的细胞中上调，而在 ATF3 过表达的细胞中下调。染色质免疫沉淀试验表明 ATF3 结合 IFI6 和 IFI27 基因的启动子区域。IFI6 和 IFI27 在 TSCC 活检组织中均高表达，在 TSCC 细胞中敲低 IFI6 或 IFI27 可阻断 ATF3 缺失引起的细胞生长和迁移。相反，过表达 IFI6 或 IFI27 可逆转 ATF3 过表达引起的 TSCC 细胞生长和迁移抑制。最后，在小鼠体内研究证实了这些体外发现。我们的研究表明，ATF3 通过负向调节其下游靶标 IFI6 和 IFI27，在 TSCC 中发挥抗肿瘤功能。
