Centre de Recherche des Cordeliers, Cell Death and Drug Resistance in Hematological Disorders Team, INSERM UMRS_1138, Sorbonne Université, Université Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Paris, France.
Sorbonne Université, Ecole Normale Supérieure, Paris Sciences & Lettres University Paris, Centre National de la Recherche Scientifique, Laboratoire des Biomolécules, Paris, France.
Blood Adv. 2019 Oct 22;3(20):2920-2933. doi: 10.1182/bloodadvances.2019000350.
Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia in Western countries, is a very heterogeneous disease characterized by a peripheral accumulation of abnormal CD5+ B lymphocytes in the immune system. Despite new therapeutic developments, there remains an unmet medical need for CLL. Here, we demonstrate that the use of N-methylated thrombospondin-1 (TSP-1)-derived peptides is an efficient way to kill the malignant CLL cells, including those from high-risk individuals with poor clinical prognosis, del11q, del17p, 2p gain, or complex karyotype. PKT16, our hit N-methylated peptide, triggers the elimination of the leukemic cells, sparing the nontumor cells, including the hematopoietic precursors, and reduces the in vivo tumor burden of a CLL-xenograft mice model. A complementary analysis underscores the improved cytotoxic efficiency of PKT16 compared with the previously described TSP-1-derived probes, such as PKHB1. PKT16 elicits an original caspase-independent programmed necrotic mode of cell death, different from necroptosis or ferroptosis, implicating an intracellular Ca2+ deregulation that provokes mitochondrial damage, cell cycle arrest, and the specific death of the malignant CLL cells. The activation of the Gαi proteins and the subsequent drop of cyclic adenosine monophosphate levels and protein kinase A activity regulate this cytotoxic cascade. Remarkably, PKT16 induces the molecular hallmarks of immunogenic cell death, as defined by the calreticulin plasma membrane exposure and the release of adenosine triphosphate and high-mobility group box 1 protein from the dying CLL cells. Thus, PKT16 appears to be able to stimulate an anticancer in vivo immune response. Collectively, our results pave the way toward the development of an efficient strategy against CLL.
慢性淋巴细胞白血病（CLL）是西方国家最常见的成人白血病，是一种非常异质性的疾病，其特征是免疫系统中异常的 CD5+ B 淋巴细胞在外周堆积。尽管有新的治疗方法发展，但 CLL 仍然存在未满足的医疗需求。在这里，我们证明使用 N-甲基化血小板反应蛋白-1（TSP-1）衍生肽是杀死恶性 CLL 细胞的有效方法，包括那些来自预后不良的高风险个体，del11q，del17p，2p 增益或复杂核型。我们的命中 N-甲基化肽 PKT16 触发白血病细胞的消除，同时保留非肿瘤细胞，包括造血前体，并减少 CLL-xenograft 小鼠模型中的体内肿瘤负担。补充分析强调了 PKT16 与先前描述的 TSP-1 衍生探针（如 PKHB1）相比，提高了细胞毒性效率。PKT16 引发了一种原始的 caspase 非依赖性程序性坏死细胞死亡模式，与坏死或铁死亡不同，涉及细胞内 Ca2+ 失调，引发线粒体损伤、细胞周期停滞和恶性 CLL 细胞的特异性死亡。Gαi 蛋白的激活和随后的环腺苷酸水平和蛋白激酶 A 活性下降调节了这种细胞毒性级联反应。值得注意的是，PKT16 诱导了免疫原性细胞死亡的分子特征，如质膜暴露钙网蛋白和从垂死的 CLL 细胞中释放三磷酸腺苷和高迁移率族框 1 蛋白。因此，PKT16 似乎能够刺激体内抗癌免疫反应。总之，我们的结果为开发针对 CLL 的有效策略铺平了道路。
