Caja Laia, Dadras Mahsa Shahidi, Mezheyeuski Artur, Rodrigues-Junior Dorival Mendes, Liu Sijia, Webb Anna Taylor, Gomez-Puerto Maria Catalina, Ten Dijke Peter, Heldin Carl-Henrik, Moustakas Aristidis
Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden.
Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
J Cell Physiol. 2022 Jan;237(1):743-762. doi: 10.1002/jcp.30542. Epub 2021 Aug 5.
The role of liver kinase B1 (LKB1) in glioblastoma (GBM) development remains poorly understood. LKB1 may regulate GBM cell metabolism and has been suggested to promote glioma invasiveness. After analyzing LKB1 expression in GBM patient mRNA databases and in tumor tissue via multiparametric immunohistochemistry, we observed that LKB1 was localized and enriched in GBM tumor cells that co-expressed SOX2 and NESTIN stemness markers. Thus, LKB1-specific immunohistochemistry can potentially reveal subpopulations of stem-like cells, advancing GBM patient molecular pathology. We further analyzed the functions of LKB1 in patient-derived GBM cultures under defined serum-free conditions. Silencing of endogenous LKB1 impaired 3D-gliomasphere frequency and promoted GBM cell invasion in vitro and in the zebrafish collagenous tail after extravasation of circulating GBM cells. Moreover, loss of LKB1 function revealed mitochondrial dysfunction resulting in decreased ATP levels. Treatment with the clinically used drug metformin impaired 3D-gliomasphere formation and enhanced cytotoxicity induced by temozolomide, the primary chemotherapeutic drug against GBM. The IC of temozolomide in the GBM cultures was significantly decreased in the presence of metformin. This combinatorial effect was further enhanced after LKB1 silencing, which at least partially, was due to increased apoptosis. The expression of genes involved in the maintenance of tumor stemness, such as growth factors and their receptors, including members of the platelet-derived growth factor (PDGF) family, was suppressed after LKB1 silencing. The defect in gliomasphere growth caused by LKB1 silencing was bypassed after supplementing the cells with exogenous PFDGF-BB. Our data support the parallel roles of LKB1 in maintaining mitochondrial homeostasis, 3D-gliomasphere survival, and hindering migration in GBM. Thus, the natural loss of, or pharmacological interference with LKB1 function, may be associated with benefits in patient survival but could result in tumor spread.
肝脏激酶B1（LKB1）在胶质母细胞瘤（GBM）发展中的作用仍知之甚少。LKB1可能调节GBM细胞代谢，并被认为可促进胶质瘤侵袭性。通过多参数免疫组织化学分析GBM患者mRNA数据库和肿瘤组织中的LKB1表达后，我们观察到LKB1定位于并富集在共表达SOX2和巢蛋白干性标志物的GBM肿瘤细胞中。因此，LKB1特异性免疫组织化学可能揭示干细胞样细胞亚群，推动GBM患者分子病理学发展。我们进一步在明确的无血清条件下分析了LKB1在患者来源的GBM培养物中的功能。内源性LKB1的沉默损害了3D胶质瘤球形成频率，并促进了GBM细胞在体外和循环GBM细胞外渗后在斑马鱼胶原尾中的侵袭。此外，LKB1功能丧失揭示了线粒体功能障碍，导致ATP水平降低。临床使用的药物二甲双胍治疗损害了3D胶质瘤球形成，并增强了替莫唑胺（治疗GBM的主要化疗药物）诱导的细胞毒性。在存在二甲双胍的情况下，替莫唑胺在GBM培养物中的IC显著降低。LKB1沉默后，这种联合效应进一步增强，这至少部分是由于细胞凋亡增加。LKB1沉默后，参与维持肿瘤干性的基因表达受到抑制，如生长因子及其受体，包括血小板衍生生长因子（PDGF）家族成员。用外源性PFDGF-BB补充细胞后，LKB1沉默导致的胶质瘤球生长缺陷被绕过。我们的数据支持LKB1在维持线粒体稳态、3D胶质瘤球存活以及阻碍GBM迁移中的平行作用。因此，LKB1功能的自然丧失或药理学干扰可能与患者生存获益相关，但可能导致肿瘤扩散。
