Department of Pathology, Osaka University Graduate School of Medicine, Osaka, Japan.
Single Cell Genomics, Human Immunology, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan.
Cancer Med. 2021 Dec;10(23):8630-8640. doi: 10.1002/cam4.4359. Epub 2021 Oct 16.
Grade 1 (G1) endometrioid carcinoma (EC) is relatively a good prognosis. However, in a minority of cases, G1 shows an aggressive histological pattern known as the microcystic, elongated, and fragmented (MELF) pattern. We previously reported that EC with high expression levels of S100A4 and serum deprivation-response protein (SDPR) was related to MELF pattern invasion. However, the molecular features of the invasive front area of the MELF pattern have not been investigated. In this study, we searched for genes preferentially expressed in the invasive front area of EC with the MELF pattern using laser microdissection and RNA sequencing, and showed that nicotinamide N-methyltransferase (NNMT) is related to MELF pattern invasiveness. Immunohistochemical analyses confirmed high NNMT expression in the invasive front area of the MELF pattern. Moreover, NNMT promoted migration, invasion, colony formation, epithelial-mesenchymal transition (EMT), and chemoresistance using EC cell lines. We speculate that depletion of NNMT promotes histone methylation and leads to tumor suppression because NNMT consumes S-adenosyl methionine (SAM), which is an essential methylation cofactor. NNMT knockout cells showed enhanced expression of H3K9me2. RNA sequencing using NNMT knockout cell lines suggested that methylation of H3K9 leads to repression of the transcription of various oncogenic genes. Our findings demonstrate the possibility that NNMT inhibitors, which are expected to be used for the treatment of metabolic disorders, would be effective for the treatment of aggressive EC. This is the first report of gene analyses focusing on the morphological changes associated with MELF pattern invasion of EC.
一级（G1）子宫内膜样癌（EC）预后相对较好。然而，在少数情况下，G1 表现出一种称为微囊状、拉长和碎片化（MELF）模式的侵袭性组织学模式。我们之前报道过，高表达 S100A4 和血清剥夺反应蛋白（SDPR）的 EC 与 MELF 模式浸润有关。然而，MELF 模式侵袭前沿区域的分子特征尚未得到研究。在这项研究中，我们使用激光微切割和 RNA 测序，在具有 MELF 模式的 EC 中寻找优先在侵袭前沿区域表达的基因，并表明烟酰胺 N-甲基转移酶（NNMT）与 MELF 模式的侵袭性有关。免疫组织化学分析证实了 MELF 模式侵袭前沿区域 NNMT 的高表达。此外，NNMT 通过 EC 细胞系促进迁移、侵袭、集落形成、上皮-间充质转化（EMT）和化疗耐药性。我们推测，NNMT 的消耗会促进组蛋白甲基化，从而导致肿瘤抑制，因为 NNMT 消耗 S-腺苷甲硫氨酸（SAM），SAM 是一种必需的甲基化辅助因子。NNMT 敲除细胞显示出 H3K9me2 的表达增强。使用 NNMT 敲除细胞系进行的 RNA 测序表明，H3K9 的甲基化导致各种致癌基因转录的抑制。我们的研究结果表明，NNMT 抑制剂有望用于治疗代谢紊乱，也可能对侵袭性 EC 有效。这是首次针对与 MELF 模式 EC 浸润相关的形态学变化进行基因分析的报告。
