Intracellular MUC20 variant 2 maintains mitochondrial calcium homeostasis and enhances drug resistance in gastric cancer
Intracellular MUC20 variant 2 maintains mitochondrial calcium homeostasis and enhances drug resistance in gastric cancer
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DOI：
10.1007/s10120-022-01283-z
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发表时间：
2022-02-15
期刊：
影响因子：
7.4
通讯作者：
Ishimoto, Takatsugu
中科院分区：
文献类型：
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作者：
Fu, Lingfeng;Yonemura, Atsuko;Ishimoto, Takatsugu
印戒细胞癌（SRCC）是胃癌的一种特殊的组织学类型.然而，与SRCC的侵蚀特性相关的关键因素尚未确定。方法收集熊本大学队列研究中360例胃癌患者的手术切除组织，通过Kaplan-Meier方法绘制生存曲线。在体外，我们通过直接测序鉴定了SRCC细胞中MUC 20的特异性转录变体，并使用MUC 20沉默和强制表达的GC细胞研究了MUC 20在GC进展中的作用。在体内，我们使用MUC 20变体2（MUC 20 v2）过表达的非SRCC细胞来构建异种移植小鼠模型来检查化学抗性。结果我们分析了一个完整的胃癌细胞系数据库，以确定在胃SRCC中特异表达的基因。我们专注于MUC 20并研究其在GC进展中的作用。生存分析显示MUC 20高表达的胃癌患者预后差，MUC 20表达与SRCC组织学类型显著相关。此外，我们发现胃SRCC细胞特异性表达MUC 20 v2，其主要表达于胞浆中。沉默MUC 20 v2引起胃SRCC细胞的细胞死亡和特征性形态学变化。为了进一步确定细胞死亡的类型，我们分别通过检测裂解的PARP、gasdermin E-N-末端（GSDME-N）和脂质活性氧（ROS）水平来检查细胞凋亡、焦亡和铁亡。我们发现MUC 20沉默的胃SRCC细胞发生凋亡和焦亡。此外，MUC 20 v2-过表达的GC细胞表现出对顺铂（CDDP）和紫杉醇（PTX）的化学抗性。RNA测序显示，参与细胞内钙调节的途径在MUC 20 v2过表达的GC细胞中显著上调。值得注意的是，MUC 20 v2在GC细胞的细胞质中的强制表达导致线粒体钙稳态和线粒体膜电位（MMP）的维持，这通过抑制凋亡和焦亡来促进细胞存活和化学抗性。最后，我们研究了MUC 20 v2在用CDDP处理的异种移植模型中的意义，并表明MUC 20 v2过表达通过抑制细胞死亡而引起化学抗性。结论MUC 20 v2可能是胃癌细胞生存和耐药的重要基因。MUC 20 v2通过维持线粒体钙离子水平和线粒体膜电位来保护GC细胞免于凋亡和焦亡，并随后诱导耐药。
Background Signet ring cell carcinoma (SRCC) is a particular histologic variant of gastric cancer (GC). However, the critical factor related to the aggressive characteristics of SRCC has not been determined. Methods We collected surgically resected tissues from 360 GC patients in the Kumamoto University cohort and generated survival curves via the Kaplan-Meier method. In vitro, we identified the specific transcript variant of MUC20 in SRCC cells by direct sequencing and investigated the role of MUC20 in GC progression using GC cells with MUC20 silencing and forced expression. In vivo, we examined chemoresistance using MUC20 variant 2 (MUC20v2)-overexpressing non-SRCC cells to construct a xenograft mouse model. Results We analyzed a comprehensive GC cell line database to identify the specifically expressed genes in gastric SRCC. We focused on MUC20 and investigated its role in GC progression. Survival analysis revealed that GC patients with high MUC20 expression exhibited a poor prognosis and that MUC20 expression was significantly correlated with SRCC histological type. Moreover, we found that gastric SRCC cells specifically expressed MUC20v2, which was dominantly expressed in the cytoplasm. Silencing MUC20v2 caused cell death with characteristic morphological changes in gastric SRCC cells. To further determine the types of cell death, we examined apoptosis, pyroptosis and ferroptosis by detecting cleaved PARP, gasdermin E-N-terminal (GSDME-N), and lipid reactive oxygen species (ROS) levels, respectively. We found that apoptosis and pyroptosis occurred in MUC20-silenced gastric SRCC cells. In addition, MUC20v2-overexpressing GC cells exhibited chemoresistance to cisplatin (CDDP) and paclitaxel (PTX). RNA sequencing revealed that the pathways involved in intracellular calcium regulation were significantly upregulated in MUC20v2-overexpressing GC cells. Notably, forced expression of MUC20v2 in the cytoplasm of GC cells led to the maintenance of mitochondrial calcium homeostasis and mitochondrial membrane potential (MMP), which promoted cell survival and chemoresistance by suppressing apoptosis and pyroptosis. Finally, we investigated the significance of MUC20v2 in a xenograft model treated with CDDP and showed that MUC20v2 overexpression caused chemoresistance by inhibiting cell death. Conclusion These findings highlight the novel functions of MUC20v2, which may confer cell survival and drug resistance in GC cells. Significance MUC20v2 protects GC cells from apoptosis and pyroptosis by maintaining mitochondrial calcium levels and mitochondrial membrane potential and subsequently induces drug resistance.