Illiano Michela, Conte Mariarosaria, Salzillo Alessia, Ragone Angela, Spina Annamaria, Nebbioso Angela, Altucci Lucia, Sapio Luigi, Naviglio Silvio
Department of Precision Medicine, University of Campania Luigi Vanvitelli, Naples, Italy.
Front Oncol. 2020 Jun 5;10:799. doi: 10.3389/fonc.2020.00799. eCollection 2020.
Acute myeloid leukemia (AML) is a progressive hematopoietic-derived cancer arising from stepwise genetic mutations of the myeloid lineage. cAMP response element-binding protein (CREB) is a nuclear transcription factor, which plays a key role in the multistep process of leukemogenesis, thus emerging as an attractive potential drug target for AML treatment. Since epigenetic dysregulations, such as DNA methylation, histone modifications, as well as chromatin remodeling, are a frequent occurrence in AML, an increasing and selective number of epi-drugs are emerging as encouraging therapeutic agents. Here, we demonstrate that the histone lysine demethylases (KDMs) JMJD3/UTX inhibitor GSKJ4 results in both proliferation decrease and CREB protein downregulation in AML cells. We found that GSKJ4 clearly decreases CREB protein, but not CREB mRNA levels. By cycloheximide assay, we provide evidence that GSKJ4 reduces CREB protein stability; moreover, proteasome inhibition largely counteracts the GSKJ4-induced CREB downregulation. Very interestingly, a rapid CREB phosphorylation at the Ser133 residue precedes CREB protein decrease in response to GSKJ4 treatment. In addition, protein kinase A (PKA) inhibition, but not extracellular signal-regulated kinase (ERK)1/2 inhibition, almost completely prevents both GSKJ4-induced p-Ser133-CREB phosphorylation and CREB protein downregulation. Overall, our study enforces the evidence regarding CREB as a potential druggable target, identifies the small epigenetic molecule GSKJ4 as an "inhibitor" of CREB, and encourages the design of future GSKJ4-based studies for the development of innovative approaches for AML therapy.
急性髓系白血病（AML）是一种源自髓系谱系逐步基因突变的进行性造血系统癌症。环磷酸腺苷反应元件结合蛋白（CREB）是一种核转录因子，在白血病发生的多步骤过程中起关键作用，因此成为AML治疗中一个有吸引力的潜在药物靶点。由于表观遗传失调，如DNA甲基化、组蛋白修饰以及染色质重塑，在AML中经常出现，越来越多的选择性表观遗传药物正成为令人鼓舞的治疗药物。在此，我们证明组蛋白赖氨酸去甲基化酶（KDMs）JMJD3/UTX抑制剂GSKJ4可导致AML细胞增殖减少和CREB蛋白下调。我们发现GSKJ4明显降低CREB蛋白水平，但不影响CREB mRNA水平。通过放线菌酮实验，我们提供证据表明GSKJ4降低了CREB蛋白的稳定性；此外，蛋白酶体抑制在很大程度上抵消了GSKJ4诱导的CREB下调。非常有趣的是，在对GSKJ4治疗的反应中，CREB蛋白减少之前，Ser133残基处会迅速发生CREB磷酸化。此外，蛋白激酶A（PKA）抑制而非细胞外信号调节激酶（ERK）1/2抑制几乎完全阻止了GSKJ4诱导的p-Ser133-CREB磷酸化和CREB蛋白下调。总体而言，我们的研究强化了关于CREB作为潜在可药物作用靶点的证据，确定了小表观遗传分子GSKJ4为CREB的“抑制剂”，并鼓励开展未来基于GSKJ4的研究，以开发AML治疗的创新方法。
