Nozawa Akifumi, Ozeki Michio, Yasue Shiho, Endo Saori, Noguchi Kei, Kanayama Tomohiro, Tomita Hiroyuki, Aoki Yoko, Ohnishi Hidenori
Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan.
Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan.
Pediatr Blood Cancer. 2021 Oct;68(10):e29086. doi: 10.1002/pbc.29086. Epub 2021 Apr 29.
Kaposiform lymphangiomatosis (KLA) is a recently characterized systemic lymphatic anomaly. Activation of RAS/MAPK and PI3K/AKT/mTOR pathways may affect KLA pathogenesis, but the cellular basis of KLA is unclear. Abnormal-spindle endothelial cells that express lymphatic endothelial cell (LEC) markers are characteristic of KLA histopathology. This study evaluated patient-derived KLA cells to establish their morphological and biological characteristics.
We established cell lines from primary KLA tissues of two patients with KLA and examined their morphological and functional characteristics, messenger RNA and protein expression profiles, gene mutations, and responses to inhibitors of the RAS/MAPK and PI3K/AKT/mTOR pathways.
Both KLA cell lines showed spindle-shaped morphology, stained positive for podoplanin (PDPN), and exhibited impaired tube-formation properties. They expressed LEC marker PDPN and mesenchymal stem cell markers (CD90, CD105) in the absence of endothelial cell markers (CD34, CD31, VWF), per real-time polymerase chain reaction. Both mTOR inhibitor rapamycin and MEK inhibitor trametinib inhibited growth of the two cell lines. A NRAS p.Q61R variant was found in one of two independent KLA tissue samples, but not in the KLA cells (per targeted next-generation sequencing); and KLA cells with this variant had elevated AKT phosphorylation levels. ERK phosphorylation levels were undetectable in both KLA cell lines.
Inhibition of the RAS/MAPK and PI3K/AKT/mTOR pathways may represent potential therapeutic targets in KLA. These patient-derived KLA cell lines will be useful research tools to elucidate KLA etiology, and could pave the way for basic, translational, and preclinical studies of this disease.
卡波西样淋巴管瘤病（KLA）是一种最近才被明确特征的系统性淋巴管异常疾病。RAS/MAPK和PI3K/AKT/mTOR信号通路的激活可能影响KLA的发病机制，但KLA的细胞基础尚不清楚。表达淋巴管内皮细胞（LEC）标志物的异常纺锤形内皮细胞是KLA组织病理学的特征。本研究评估了源自患者的KLA细胞，以确定其形态和生物学特性。
我们从两名KLA患者的原发性KLA组织中建立了细胞系，并检测了它们的形态和功能特征、信使核糖核酸和蛋白质表达谱、基因突变以及对RAS/MAPK和PI3K/AKT/mTOR信号通路抑制剂的反应。
两种KLA细胞系均呈纺锤形形态，血小板内皮细胞黏附分子（PDPN）染色呈阳性，且其成管特性受损。实时聚合酶链反应结果显示，它们表达LEC标志物PDPN和间充质干细胞标志物（CD90、CD105），而不表达内皮细胞标志物（CD34、CD31、血管性血友病因子）。mTOR抑制剂雷帕霉素和MEK抑制剂曲美替尼均抑制了这两种细胞系的生长。在两个独立的KLA组织样本中的一个中发现了NRAS p.Q61R变异，但在KLA细胞中未发现（通过靶向二代测序）；具有该变异的KLA细胞的AKT磷酸化水平升高。两种KLA细胞系中均未检测到ERK磷酸化水平。
抑制RAS/MAPK和PI3K/AKT/mTOR信号通路可能是KLA的潜在治疗靶点。这些源自患者的KLA细胞系将成为阐明KLA病因的有用研究工具，并可能为该疾病的基础研究、转化研究和临床前研究铺平道路。
