RING finger protein 135 (RNF135) is identified as a regulator in certain cancer types. However, its role and molecular mechanisms in lung adenocarcinoma (LUAD) are still unclear. Herein, we investigated the level of RNF135 in tumor tissues of LUAD patients using the UALCAN database and confirmed the data by real‐time PCR and western blot analysis. The effects of RNF135 on stemness maintenance and migration/invasion capability of LUAD cells were investigated by sphere formation, flow cytometry, wound healing, and transwell assay. Limiting dilution xenograft assay and intracardiac injection of LUAD cells were applied to assess the implications of RNF135 in tumorigenesis and brain metastasis. Our results revealed that RNF135 was upregulated in tumor tissues of LUAD patients and was positively correlated with poor prognosis. Knockdown of RNF135 suppressed cancer stem cells (CSCs)‐like properties, and migration/invasion capability of A549 and NCI‐H1975 cells. Conversely, overexpression of RNF135 augmented CSCs‐like traits and migration/invasion ability of LUAD cells. Limiting dilution xenograft assay demonstrated that RNF135 was required for the self‐renewal of CSCs to initiate LUAD development. Overexpression of RNF135 in A549 cells increased their ability to metastasize to the brain in vivo. Mechanistically, the transcriptional activation of RNF135 by LSD1 involved H3K9me2 demethylation at the promoter region of RNF135. Reexpression of RNF135 in LSD1‐silenced A549 cells was able to reverse LSD1‐mediated stemness maintenance and migration/invasion capability. Overall, our results implied that targeting of LSD1/RNF135 axis might be a feasible method to suppress tumorigenesis and brain metastasis of LUAD patients.

中文翻译：

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LSD1 对 RNF135 的表观遗传调控促进肺腺癌干性维持和脑转移


RING finger 蛋白 135 （RNF135） 被确定为某些癌症类型的调节因子。然而，它在肺腺癌 （LUAD） 中的作用和分子机制仍不清楚。在此，我们使用 UALCAN 数据库研究了 LUAD 患者肿瘤组织中 RNF135 的水平，并通过实时 PCR 和 western blot 分析证实了数据。通过球形成、流式细胞术、伤口愈合和 transwell 测定研究 RNF135 对 LUAD 细胞干性维持和迁移/侵袭能力的影响。应用有限稀释异种移植试验和心内注射 LUAD 细胞来评估 RNF135 在肿瘤发生和脑转移中的影响。我们的结果显示，RNF135 在 LUAD 患者的肿瘤组织中上调，并且与不良预后呈正相关。敲低 RNF135 抑制了癌症干细胞 （CSC） 样特性，以及 A549 和 NCI-H1975 细胞的迁移/侵袭能力。相反，RNF135 的过表达增强了 LUAD 细胞的 CSCs 样性状和迁移/侵袭能力。有限稀释异种移植试验表明，RNF135 是 CSCs 自我更新启动 LUAD 发育所必需的。在 A549 细胞中过表达 RNF135 增加了它们在体内转移到大脑的能力。从机制上讲，LSD1 对 RNF135 的转录激活涉及 RNF135 启动子区的 H3K9me2 去甲基化。在 LSD1 沉默的 A549 细胞中重表达 RNF135 能够逆转 LSD1 介导的干性维持和迁移/侵袭能力。总体而言，我们的结果表明，靶向 LSD1/RNF135 轴可能是抑制 LUAD 患者肿瘤发生和脑转移的可行方法。