Université Côte d'Azur, INSERM, CNRS, IPMC, team labeled "Laboratory of Excellence (LABEX) Distalz", 660 route des Lucioles, 06560, Sophia-Antipolis, Valbonne, France.
Department of Biology, The University of North Carolina Greensboro, Greensboro, North Carolina, United States of America.
Theranostics. 2021 Nov 1;11(20):10047-10063. doi: 10.7150/thno.57549. eCollection 2021.
Parkin (PK) is an E3-ligase harboring tumor suppressor properties that has been associated to various cancer types including glioblastoma (GBM). However, PK is also a transcription factor (TF), the contribution of which to GBM etiology remains to be established. The impact of PK on GBM cells proliferation was analyzed by real-time impedance measurement and flow cytometry. Cyclins A and B proteins, promoter activities and mRNA levels were measured by western blot, luciferase assay and quantitative real-time PCR. Protein-protein and protein-promoter interactions were performed by co-immunoprecipitation and by ChIP approaches. The contribution of endogenous PK to tumor progression was performed by allografts of GL261 GBM cells in wild-type and PK knockout mice. We show that overexpressed and endogenous PK control GBM cells proliferation by modulating the S and G2/M phases of the cell cycle via the trans-repression of A and genes. We establish that cyclin B is regulated by both E3-ligase and TF PK functions while cyclin A is exclusively regulated by PK TF function. PK invalidation leads to enhanced tumor progression in immunocompetent mice suggesting an impact of PK-dependent tumor environment to tumor development. We show that PK is secreted by neuronal cells and recaptured by tumor cells. Recaptured PK lowered cyclins levels and decreased GBM cells proliferation. Further, PK expression is decreased in human GBM biopsies and its expression is inversely correlated to both cyclins A and B expressions. Our work demonstrates that PK tumor suppressor function contributes to the control of tumor by its cellular environment. It also shows a key role of PK TF function in GBM development via the control of cyclins and . It suggests that therapeutic strategies aimed at controlling PK shuttling to the nucleus may prove useful to treat GBM.
Parkin（PK）是一种具有肿瘤抑制特性的 E3 连接酶，与包括神经胶质瘤（GBM）在内的多种癌症类型有关。然而，PK 也是一种转录因子（TF），其对 GBM 病因的贡献尚待确定。通过实时阻抗测量和流式细胞术分析 PK 对 GBM 细胞增殖的影响。通过 Western blot、荧光素酶测定和定量实时 PCR 测量细胞周期蛋白 A 和 B 蛋白、启动子活性和 mRNA 水平。通过共免疫沉淀和 ChIP 方法研究蛋白质-蛋白质和蛋白质-启动子相互作用。通过将 GL261 GBM 细胞同种异体移植到野生型和 PK 敲除小鼠中来研究内源性 PK 对肿瘤进展的贡献。我们表明，过表达和内源性 PK 通过反式抑制 A 和 B 基因来调节细胞周期的 S 和 G2/M 期来控制 GBM 细胞的增殖。我们确定 cyclin B 受 E3 连接酶和 TF PK 功能的调节，而 cyclin A 仅受 PK TF 功能的调节。PK 失活导致免疫功能正常的小鼠中的肿瘤进展增强，这表明 PK 依赖性肿瘤微环境对肿瘤发展有影响。我们表明，PK 由神经元细胞分泌并被肿瘤细胞重新捕获。重新捕获的 PK 降低了 cyclin 水平并降低了 GBM 细胞的增殖。此外，PK 在人类 GBM 活检中的表达降低，其表达与 cyclin A 和 B 的表达呈负相关。我们的工作表明，PK 的肿瘤抑制功能通过其细胞环境有助于控制肿瘤。它还通过控制 cyclins 和 显示 PK TF 功能在 GBM 发育中的关键作用。它表明，旨在控制 PK 穿梭到细胞核的治疗策略可能有助于治疗 GBM。
