Lee Jung Kwon, Wang Xidi, Wang Jinghua, Rosales Jesusa L, Lee Ki-Young
Department of Cell Biology & Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, University of Calgary, Calgary, AB, Canada.
Department of Pathogen Biology and Immunology, Health Science Center, Ningbo University, Ningbo, China.
Cell Death Discov. 2024 May 27;10(1):257. doi: 10.1038/s41420-024-02028-w.
Despite the success in treating newly diagnosed pediatric acute lymphoblastic leukemia (aLL), the long-term cure rate for the 20% of children who relapse is poor, making relapsed aLL the primary cause of cancer death in children. By unbiased genome-wide retroviral RNAi screening and knockdown studies, we previously discovered opioid receptor mu 1 (OPRM1) as a new aLL cell resistance biomarker for the aLL chemotherapeutic drug, L-asparaginase, i.e., OPRM1 loss triggers L-asparaginase resistance. Indeed, aLL cell OPRM1 level is inversely proportional to L-asparaginase IC50: the lower the OPRM1 level, the higher the L-asparaginase IC50, indicating that aLL cells expressing reduced OPRM1 levels show resistance to L-asparaginase. In the current study, we utilized OPRM1-expressing and -knockdown aLL cells as well as relapsed patient aLL cells to identify candidate targeted therapy for L-asparaginase-resistant aLL. In OPRM1-expressing cells, L-asparaginase induces apoptosis via a cascade of events that include OPRM1-mediated decline in [cAMP], downregulation of PKA-mediated BAD S phosphorylation that can be reversed by 8-CPT-cAMP, cyt C release from the mitochondria, and subsequent caspase activation and PARP1 cleavage. The critical role of PKA inhibition due to a decrease in [cAMP] in this apoptotic process is evident in the killing of OPRM1-knockdown and low OPRM1-expressing relapsed patient aLL cells by the PKA inhibitors, H89 and 14-22 amide. These findings demonstrate for the first time that PKA can be targeted to kill aLL cells resistant to L-asparaginase due to OPRM1 loss, and that H89 and 14-22 amide may be utilized to destroy L-asparaginase-resistant patient aLL cells.
尽管在治疗新诊断的儿童急性淋巴细胞白血病（ALL）方面取得了成功，但20%复发儿童的长期治愈率很低，这使得复发ALL成为儿童癌症死亡的主要原因。通过无偏倚的全基因组逆转录病毒RNAi筛选和敲低研究，我们先前发现阿片受体μ1（OPRM1）是ALL化疗药物L-天冬酰胺酶的一种新的ALL细胞耐药生物标志物，即OPRM1缺失会引发L-天冬酰胺酶耐药。事实上，ALL细胞的OPRM1水平与L-天冬酰胺酶的IC50成反比：OPRM1水平越低，L-天冬酰胺酶的IC50越高，这表明表达降低的OPRM1水平的ALL细胞对L-天冬酰胺酶具有抗性。在当前的研究中，我们利用表达OPRM1和敲低OPRM1的ALL细胞以及复发患者的ALL细胞来确定针对L-天冬酰胺酶耐药ALL的候选靶向治疗方法。在表达OPRM1的细胞中，L-天冬酰胺酶通过一系列事件诱导细胞凋亡，这些事件包括OPRM1介导的[cAMP]下降、PKA介导的BAD S磷酸化的下调，8-CPT-cAMP可逆转这种下调、细胞色素C从线粒体释放以及随后的半胱天冬酶激活和PARP1裂解。在PKA抑制剂H89和14-22酰胺对OPRM1敲低和低OPRM1表达的复发患者ALL细胞的杀伤作用中，[cAMP]降低导致的PKA抑制在这一凋亡过程中的关键作用是显而易见的。这些发现首次证明，由于OPRM1缺失而对L-天冬酰胺酶耐药的ALL细胞可以通过靶向PKA来杀死，并且H89和14-22酰胺可用于破坏对L-天冬酰胺酶耐药的患者ALL细胞。
