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%的复发儿童的长期治愈率很低，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，我们之前发现阿片受体mu 1（OPRM1）作为aLL化疗药物L-天冬酰胺酶的新aLL细胞耐药生物标志物，即OPRM1丢失会触发L-天冬酰胺酶耐药。事实上，aLL细胞OPRM1水平与L-天冬酰胺酶IC50成反比：OPRM1水平越低，L-天冬酰胺酶IC50越高，表明表达降低的OPRM1水平的aLL细胞表现出对L-天冬酰胺酶的抗性。在当前的研究中，我们利用表达和敲低 OPRM1 的 aLL 细胞以及复发患者的 aLL 细胞来确定 L-天冬酰胺酶耐药性 aLL 的候选靶向治疗。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，包括 OPRM1 介导的 [cAMP]i 下降、PKA 介导的 BAD S118 磷酸化下调（可通过 8-CPT-cAMP 逆转）、细胞色素 C 释放来自线粒体，以及随后的 caspase 激活和 PARP1 裂解。在这种细胞凋亡过程中，由于 [cAMP]i 减少而导致的 PKA 抑制的关键作用在 PKA 抑制剂 H89 和 14-22 酰胺杀死 OPRM1 敲低和低 OPRM1 表达的复发患者 aLL 细胞时表现得很明显。这些发现首次证明，PKA 可以靶向杀死因 OPRM1 丢失而对 L-天冬酰胺酶耐药的 aLL 细胞，并且 H89 和 14-22 酰胺可用于破坏 L-天冬酰胺酶耐药的患者 aLL 细胞。© 2024 . 作者。

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]i, downregulation of PKA-mediated BAD S118 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]i 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.© 2024. The Author(s).