Illiano Michela, Conte Mariarosaria, Sapio Luigi, Nebbioso Angela, Spina Annamaria, Altucci Lucia, Naviglio Silvio
Department of Precision Medicine, School of Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy.
IRCCS SDN, Napoli Via E. Gianturco, Naples, Italy.
Front Pharmacol. 2018 Jul 20;9:792. doi: 10.3389/fphar.2018.00792. eCollection 2018.
Acute myeloid leukemia (AML) is an aggressive hematological malignancy occurring very often in older adults, with poor prognosis depending on both rapid disease progression and drug resistance occurrence. Therefore, new therapeutic approaches are demanded. Epigenetic marks play a relevant role in AML. GSKJ4 is a novel inhibitor of the histone demethylases JMJD3 and UTX. To note GSKJ4 has been recently shown to act as a potent small molecule inhibitor of the proliferation in many cancer cell types. On the other hand, forskolin, a natural cAMP raising compound, used for a long time in traditional medicine and considered safe also in recent studies, is emerging as a very interesting molecule for possible use in cancer therapy. Here, we investigate the effects of forskolin on the sensitivity of human leukemia U937 cells to GSKJ4 through flow cytometry-based assays (cell-cycle progression and cell death), cell number counting, and immunoblotting experiments. We provide evidence that forskolin markedly potentiates GSKJ4-induced antiproliferative effects by apoptotic cell death induction, accompanied by a dramatic BCL2 protein down-regulation as well as caspase 3 activation and PARP protein cleavage. Comparable effects are observed with the phosphodiesterase inhibitor IBMX and 8-Br-cAMP analogous, but not by using 8-pCPT-2'-O-Me-cAMP Epac activator. Moreover, the forskolin-induced enhancement of sensitivity to GSKJ4 is counteracted by pre-treatment with Protein Kinase A (PKA) inhibitors. Altogether, our data strongly suggest that forskolin sensitizes U937 cells to GSKJ4 inhibitor via a cAMP/PKA-mediated mechanism. Our findings provide initial evidence of anticancer activity induced by forskolin/GSKJ4 combination in leukemia cells and underline the potential for use of forskolin and GSKJ4 in the development of innovative and effective therapeutic approaches for AML treatment.
急性髓系白血病（AML）是一种侵袭性血液系统恶性肿瘤，在老年人中很常见，由于疾病进展迅速和出现耐药性，其预后较差。因此，需要新的治疗方法。表观遗传标记在AML中发挥着重要作用。GSKJ4是组蛋白去甲基化酶JMJD3和UTX的新型抑制剂。值得注意的是，最近研究表明GSKJ4在许多癌细胞类型中作为一种有效的小分子增殖抑制剂发挥作用。另一方面，福司可林是一种天然的环磷酸腺苷（cAMP）升高化合物，长期用于传统医学，并且在最近的研究中也被认为是安全的，它正成为一种非常有前景的分子，可能用于癌症治疗。在这里，我们通过基于流式细胞术的检测（细胞周期进程和细胞死亡）、细胞计数和免疫印迹实验，研究了福司可林对人白血病U937细胞对GSKJ4敏感性的影响。我们提供的证据表明，福司可林通过诱导凋亡性细胞死亡显著增强了GSKJ4诱导的抗增殖作用，同时伴随着BCL2蛋白的显著下调以及半胱天冬酶3的激活和PARP蛋白的裂解。磷酸二酯酶抑制剂IBMX和8-溴-cAMP类似物也观察到了类似的效果，但使用8-pCPT-2'-O-Me-cAMP Epac激活剂则没有。此外，用蛋白激酶A（PKA）抑制剂预处理可抵消福司可林诱导的对GSKJ4敏感性的增强。总之，我们的数据强烈表明，福司可林通过cAMP/PKA介导的机制使U937细胞对GSKJ4抑制剂敏感。我们的研究结果为福司可林/GSKJ4联合用药在白血病细胞中诱导的抗癌活性提供了初步证据，并强调了福司可林和GSKJ4在开发创新有效的AML治疗方法中的潜在用途。
