Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan.
Biochem Biophys Res Commun. 2020 Aug 27;529(3):582-589. doi: 10.1016/j.bbrc.2020.05.168. Epub 2020 Jul 17.
Mitochondria-eating protein (Mieap) plays a critical role in mitochondrial quality control (MQC) and functions as a p53-inducible tumor suppressor. This study aimed to examine its role in gastric cancer (GC) and esophageal cancer (EC). GC cells were infected with Mieap-overexpressing adenovirus (Ad-Mieap) and subjected to fluorescence-activated cell sorting (FACS), western blotting, and caspase assays. Thereafter, we evaluated the potential disruption of the p53/Mieap-regulated MQC pathway in vivo. Methylation-specific PCR (MSP) for Mieap, NIX, and BNIP3 promoters was performed and p53 mutations were detected using cryopreserved surgical specimens. Exogenous Mieap in GC cells induced the formation of vacuole-like structures (called MIVs, Mieap-induced vacuoles) and caspase-dependent cell death, with the activation of both caspase-3 and caspase-9. Of the 47 GC patients, promoter methylation in Mieap, BNIP3, and NIX was identified in two (4.3%), 29 (61.7%), and zero (0%) specimens, respectively. In total, 33 GC patients (70.2%) inactivated this MQC pathway. Amazingly, BNIP3 promoter in the normal epithelium was highly methylated in 18 of the 47 GC patients (38.3%). In EC patients, this MQC pathway was also inactivated in ten of 12 patients (83.3%). These results indicate that p53/Mieap-regulated MQC plays an important role in upper gastrointestinal (GI) tumor suppression, possibly, in part, through the mitochondrial apoptotic pathway.
线粒体自噬蛋白（Mieap）在维持线粒体质量控制（MQC）中起着关键作用，并作为 p53 诱导的肿瘤抑制因子发挥作用。本研究旨在探讨其在胃癌（GC）和食管癌（EC）中的作用。GC 细胞感染 Mieap 过表达腺病毒（Ad-Mieap），并进行荧光激活细胞分选（FACS）、western blot 和半胱天冬酶测定。随后，我们评估了体内 p53/Mieap 调节的 MQC 通路的潜在破坏。采用甲基化特异性 PCR（MSP）检测 Mieap、NIX 和 BNIP3 启动子的甲基化，并用冷冻保存的手术标本检测 p53 突变。GC 细胞中的外源性 Mieap 诱导形成空泡样结构（称为 MIVs，Mieap 诱导的空泡）和依赖半胱天冬酶的细胞死亡，同时激活 caspase-3 和 caspase-9。在 47 例 GC 患者中，有 2 例（4.3%）、29 例（61.7%）和 0 例（0%）患者的 Mieap、BNIP3 和 NIX 启动子发生甲基化。总的来说，33 例（70.2%）GC 患者失活了这条 MQC 通路。令人惊讶的是，47 例 GC 患者中有 18 例（38.3%）正常上皮的 BNIP3 启动子高度甲基化。在 EC 患者中，这条 MQC 通路在 12 例患者中的 10 例（83.3%）中也失活了。这些结果表明，p53/Mieap 调节的 MQC 在抑制上消化道（GI）肿瘤中起着重要作用，可能部分通过线粒体凋亡途径。
