Leiden Academic Center for Drug Research, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands.
Int J Mol Sci. 2023 Jan 28;24(3):2512. doi: 10.3390/ijms24032512.
The transcription factor Grainyhead-like 2 (GRHL2) is a critical transcription factor for epithelial tissues that has been reported to promote cancer growth in some and suppress aspects of cancer progression in other studies. We investigated its role in different breast cancer subtypes. In breast cancer patients, GRHL2 expression was increased in all subtypes and inversely correlated with overall survival in basal-like breast cancer patients. In a large cell line panel, GRHL2 was expressed in luminal and basal A cells, but low or absent in basal B cells. The intersection of ChIP-Seq analysis in 3 luminal and 3 basal A cell lines identified conserved GRHL2 binding sites for both subtypes. A pathway analysis of ChIP-seq data revealed cell-cell junction regulation and epithelial migration as well as epithelial proliferation, as candidate GRHL2-regulated processes and further analysis of hub genes in these pathways showed similar regulatory networks in both subtypes. However, GRHL2 deletion in a luminal cell line caused cell cycle arrest while this was less prominent in a basal A cell line. Conversely, GRHL2 loss triggered enhanced migration in the basal A cells but failed to do so in the luminal cell line. ChIP-Seq and ChIP-qPCR demonstrated GRHL2 binding to CLDN4 and OVOL2 in both subtypes but not to other GRHL2 targets controlling cell-cell adhesion that were previously identified in other cell types, including CDH1 and ZEB1. Nevertheless, E-cadherin protein expression was decreased upon GRHL2 deletion especially in the luminal line and, in agreement with its selectively enhanced migration, only the basal A cell line showed concomitant induction of vimentin and N-cadherin. To address how the balance between growth reduction and aspects of EMT upon loss of GRHL2 affected in vivo behavior, we used a mouse basal A orthotopic transplantation model in which the GRHL2 gene was silenced. This resulted in reduced primary tumor growth and a reduction in number and size of lung colonies, indicating that growth suppression was the predominant consequence of GRHL2 loss. Altogether, these findings point to largely common but also distinct roles for GRHL2 in luminal and basal breast cancers with respect to growth and motility and indicate that, in agreement with its negative association with patient survival, growth suppression is the dominant response to GRHL2 loss.
转录因子 Grainyhead-like 2（GRHL2）是上皮组织中一种关键的转录因子，有研究报道称其在某些情况下促进癌症生长，而在其他研究中则抑制癌症进展的某些方面。我们研究了其在不同乳腺癌亚型中的作用。在乳腺癌患者中，所有亚型的 GRHL2 表达均增加，基底样乳腺癌患者的总生存与 GRHL2 表达呈负相关。在一个大型细胞系面板中，GRHL2 在 luminal 和 basal A 细胞中表达，但在 basal B 细胞中低表达或缺失。在 3 个 luminal 和 3 个 basal A 细胞系中的 ChIP-Seq 分析的交集确定了两种亚型都有保守的 GRHL2 结合位点。ChIP-seq 数据的通路分析显示细胞-细胞连接调节和上皮迁移以及上皮增殖，作为候选的 GRHL2 调控过程，对这些通路中的枢纽基因的进一步分析表明，两种亚型都有类似的调控网络。然而，在 luminal 细胞系中删除 GRHL2 会导致细胞周期停滞，而在 basal A 细胞系中则不明显。相反，GRHL2 缺失会触发 basal A 细胞的迁移增强，但在 luminal 细胞系中则不会。ChIP-Seq 和 ChIP-qPCR 证明了 GRHL2 在两种亚型中与 CLDN4 和 OVOL2 结合，但与以前在其他细胞类型中发现的控制细胞-细胞黏附的其他 GRHL2 靶标（包括 CDH1 和 ZEB1）不同。然而，GRHL2 缺失后 E-钙黏蛋白蛋白表达减少，尤其是在 luminal 细胞系中，并且与选择增强的迁移一致，只有 basal A 细胞系显示伴随波形蛋白和 N-钙黏蛋白的诱导。为了解决 GRHL2 缺失后生长减少和 EMT 方面的某些方面之间的平衡如何影响体内行为，我们使用了一种 GRHL2 基因沉默的小鼠 basal A 原位移植模型。这导致原发性肿瘤生长减少，肺集落的数量和大小减少，表明生长抑制是 GRHL2 缺失的主要后果。总之，这些发现表明，在生长和运动方面，GRHL2 在 luminal 和 basal 乳腺癌中具有很大的共同作用，但也有明显的区别，并且与患者生存的负相关一致，生长抑制是对 GRHL2 缺失的主要反应。
