Purpose

Urinary bladder urothelial carcinoma (UBUC) is a common malignant disease, and its high recurrence rates impose a heavy clinical burden. The objective of this study was to identify signaling pathways downstream of epithelial membrane protein 2 (EMP2), which induces cytostasis and apoptosis in UBUC.

Methods

A series of in vitro and in vivo assays using different UBUC-derived cell lines and mouse xenograft models were performed, respectively. In addition, primary UBUC specimens were evaluated by immunohistochemistry.

Results

Exogenous expression of EMP2 in J82 UBUC cells significantly decreased DNA replication and altered the expression levels of several TGFβ signaling-related proteins. EMP2 knockdown in BFTC905 UBUC cells resulted in opposite effects. EMP2-dysregulated cell cycle progression was found to be mediated by the TGFβ/TGFBR1/SP1 family member SMAD. EMP2 or purinergic receptor P2X7 (P2RX7) gene expression upregulation induced apoptosis via both intrinsic and extrinsic pathways. In 242 UBUC patient samples, P2RX7 protein levels were found to be significantly and positively correlated with EMP2 protein levels. Low P2RX7 levels conferred poor disease-specific and metastasis-free survival rates, and significantly decreased apoptotic cell rates. EMP2 was found to physically interact with P2RX7. In the presence of a P2RX7 agonist, BzATP, overexpression of both EMP2 and P2RX7 significantly increased apoptotic cell rates compared to overexpression of EMP2 or P2RX7 alone.

Conclusions

EMP2 induces cytostasis via the TGFβ/SMAD/SP1 axis and recruits P2RX7 to enhance apoptosis in UBUC. Our data provide new insights that may be employed for the design of UBUC targeting therapies.

中文翻译：

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EMP2通过TGFβ/SMAD/SP1轴诱导膀胱尿路上皮癌中的细胞抑制和细胞凋亡以及P2RX7的募集

目的

膀胱尿路上皮癌（UBUC）是一种常见的恶性疾病，其高复发率给临床带来了沉重的负担。本研究的目的是确定上皮膜蛋白 2 (EMP2) 下游的信号通路，它在 UBUC 中诱导细胞抑制和细胞凋亡。

方法

分别使用不同的 UBUC 衍生细胞系和小鼠异种移植模型进行了一系列体外和体内测定。此外，通过免疫组织化学评估原发性 UBUC 标本。

结果

J82 UBUC 细胞中EMP2的外源表达显着降低了 DNA 复制并改变了几种 TGFβ 信号相关蛋白的表达水平。BFTC905 UBUC 细胞中的EMP2敲低导致相反的效果。发现 EMP2 失调的细胞周期进程是由 TGFβ/TGFBR1/SP1 家族成员 SMAD 介导的。EMP2或嘌呤能受体 P2X7 ( P2RX7) 基因表达上调通过内在和外在途径诱导细胞凋亡。在 242 例 UBUC 患者样本中，发现 P2RX7 蛋白水平与 EMP2 蛋白水平显着正相关。低 P2RX7 水平导致疾病特异性和无转移存活率低，并显着降低凋亡细胞率。EMP2 被发现与 P2RX7 物理交互。在存在 P2RX7 激动剂 BzATP 的情况下，与单独过表达EMP2或P2RX7相比， EMP2和P2RX7的过表达显着增加了凋亡细胞率。

结论

EMP2 通过 TGFβ/SMAD/SP1 轴诱导细胞抑制并募集 P2RX7 以增强 UBUC 中的细胞凋亡。我们的数据提供了新的见解，可用于设计 UBUC 靶向疗法。