Yamada Daisuke, Takahashi Kensuke, Kawahara Kohichi, Maeda Takehiko
Department of Pharmacology, Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Akiha-ku, Niigata-city, Niigata 956-8603, Japan.
Department of Pharmacology, Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Akiha-ku, Niigata-city, Niigata 956-8603, Japan.
Biochem Biophys Res Commun. 2016 Nov 18;480(3):375-379. doi: 10.1016/j.bbrc.2016.10.057. Epub 2016 Oct 19.
Cancer stem-like cells (CSCs) exist in tumor tissues composed of heterogeneous cell population and are characterized by their self-renewal capacity and tumorigenicity. Many studies demonstrate that eradication of CSCs prevents development and recurrences of tumor; yet, molecules critical for the maintenance of CSCs have not been completely understood. We previously reported that Semaphorin3A (Sema3a) knockdown suppressed the tumorigenicity and proliferative capacity of Lewis lung carcinoma (LLC) cells. Therefore, we identified Sema3a as an essential factor for the establishment or maintenance of CSCs derived from LLC (LLC-stem cell). shRNA against Sema3a was introduced into LLC cells to establish a LLC-stem cell line and its effects on tumorigenesis, sphere formation, and mTORC1 activity were tested. Sema3a knockdown completely abolished tumorigenicity and the sphere-formation and self-renewal ability of LLC-stem cells. The Sema3a knockdown was also associated with decreased expression of mRNA for stem cell markers. The self-renewal ability abolished by Sema3a knockdown could not be recovered by exogenous addition of recombinant SEMA3A. In addition, the activity of mammalian target of rapamycin complex 1 (mTORC1) and the expression of its substrate p70S6K1 were also decreased. These results demonstrate that Sema3a is a potential therapeutic target in eradication of CSCs.
癌症干细胞（CSCs）存在于由异质性细胞群体组成的肿瘤组织中，其特征在于自我更新能力和致瘤性。许多研究表明，清除CSCs可预防肿瘤的发展和复发；然而，维持CSCs的关键分子尚未完全明确。我们之前报道，Semaphorin3A（Sema3a）敲低可抑制Lewis肺癌（LLC）细胞的致瘤性和增殖能力。因此，我们确定Sema3a是源自LLC的CSCs（LLC干细胞）建立或维持的关键因素。将针对Sema3a的短发夹RNA（shRNA）导入LLC细胞以建立LLC干细胞系，并测试其对肿瘤发生、球体形成和mTORC1活性的影响。Sema3a敲低完全消除了LLC干细胞的致瘤性、球体形成和自我更新能力。Sema3a敲低还与干细胞标志物的mRNA表达降低有关。通过外源性添加重组SEMA3A无法恢复因Sema3a敲低而丧失的自我更新能力。此外，雷帕霉素复合物1（mTORC1）的哺乳动物靶点活性及其底物p70S6K1的表达也降低。这些结果表明，Sema3a是清除CSCs的潜在治疗靶点。
