Mechanisms of STING in malignant progression and therapy of CLL.

项目总结/摘要 慢性淋巴细胞白血病（CLL）占成人白血病的30%，仍然无法治愈。根据 根据美国国家癌症研究所的数据，预计2020年将有大约21，250例CLL新发病例和4，320例CLL死亡病例。 美国在2021年。虽然布鲁顿氏酪氨酸激酶抑制剂（BTKi）是一种有效的靶向 在CLL的治疗中，大约50%的BTKi治疗的CLL患者由于以下原因而退出治疗： 慢性副作用此外，用BTKi或其他治疗的CLL患者的数量显著增加， 激酶抑制剂已导致医学上更具挑战性的弥漫性大B细胞淋巴瘤。新疗法 可以直接靶向CLL或与BTKi合理组合的药物是非常需要的。干扰素刺激剂 STING基因（STING）是一种内质网（ER）驻留蛋白，对于感测细胞质DNA至关重要， 促进I型干扰素的产生，从而增强免疫反应。STING激动剂，如 ADU-S100已在临床试验中用作Pembrolizumab的联合免疫疗法，以治疗 STING激动剂的这些治疗性应用是基于 STING在引发抗肿瘤免疫中的主要已知功能。我们是第一个证明STING 激动剂在B细胞衍生的恶性肿瘤包括CLL中直接诱导有效的ARPA介导的细胞凋亡， 虽然这些激动剂在黑素瘤、肝癌和肺癌细胞中诱导干扰素的产生， 抑制他们的成长。CLL、B细胞淋巴瘤和多发性骨髓瘤的细胞凋亡需要STING，因为 STING的基因缺失导致所有这些细胞对STING激动剂介导的细胞凋亡产生抗性。 这些细胞的凋亡不是由于炎性细胞因子的产生，而是可能涉及细胞周期的延长。 存在激动剂结合的STING。加上我们新的初步结果表明，突变介导的 STING的激活导致B细胞受体（BCR）的快速降解和BCR的显著降低 STING上的新丝氨酸残基被磷酸化，从而导致CLL的存活。 激动剂刺激的恶性B细胞，我们建议识别和表征差异磷酸化， 激活STING的相互作用伙伴，以进一步了解激活STING的机制， 导致CLL中BCR降解和细胞凋亡。由于我们的初步数据显示，STING缺陷可以 导致小鼠CLL中BCR和BCR信号传导水平增加，并且小鼠和人恶性肿瘤细胞中BCR和BCR信号传导水平增加。 CLL细胞显著下调其STING的表达水平，我们将测试STING- 下调或STING缺陷型CLL细胞对BTKi的敏感性较低。我们还将研究如何改变 STING的表达和磷酸化可以调节CLL的生存、进展和化疗耐药性。 基于我们的假设，STING的激活可以导致BCR的降解并使CLL细胞 对于BTKi更敏感，我们提出将联合收割机STING激动剂与BTKi组合以治疗CLL。

Project Summary/Abstract Chronic lymphocytic leukemia (CLL) represents 30% of adult leukemia and is still incurable. According to the National Cancer Institute, approximately 21,250 new cases of CLL and 4,320 deaths from CLL are projected in the United States alone in 2021. Although the Bruton's tyrosine kinase inhibitor (BTKi) is an effective targeted therapy for CLL, approximately 50% of BTKi-treated CLL patients have dropped out of the therapy due to chronic adverse effects. Additionally, significantly increased numbers of CLL patients treated with BTKi or other kinase inhibitors have developed the more medically challenging diffuse large B cell lymphoma. Novel therapy that can directly target CLL or be rationally combined with BTKi is highly desirable. The stimulator of interferon genes (STING) is an endoplasmic reticulum (ER)-resident protein critical for sensing cytoplasmic DNA and promoting production of type I interferons, thereby boosting immune responses. STING agonists, such as ADU-S100, have been used as combination immunotherapy with Pembrolizumab in clinical trials to treat advanced solid tumors and lymphomas, and these therapeutic applications of STING agonists are based on the main known function of STING in eliciting anti-tumor immunity. We were the first to show that STING agonists directly induce potent mitochondria-mediated apoptosis in B cell-derived malignancies including CLL, while these agonists induce production of interferons in melanoma, hepatoma and lung cancer cells without suppressing their growth. Apoptosis of CLL, B cell lymphoma and multiple myeloma requires STING, because genetic deletion of STING results in resistance of all these cells to STING agonist-mediated apoptosis. Apoptosis of these cells is not due to the production of inflammatory cytokines but may involve the prolonged presence of agonist-bound STING. Together with our new preliminary results showing that mutation-mediated activation of STING causes rapid degradation of the B cell receptor (BCR) and significantly reduced BCR signaling (disadvantageous for CLL survival), and that novel serine residues on STING are phosphorylated in agonist-stimulated malignant B cells, we propose to identify and characterize differential phosphorylation and interacting partners of activated STING to further understand the mechanisms by which activated STING causes BCR degradation and apoptosis in CLL. Since our preliminary data show that STING deficiency can lead to increased levels of the BCR and BCR signaling in mouse CLL, and that mouse and human malignant CLL cells significantly downregulate their expression levels of STING, we will test whether STING- downregulated or STING-deficient CLL cells are less sensitive to BTKi. We will also examine how such altered STING expression and phosphorylation can regulate the survival, progression and chemoresistance of CLL. Based on our hypothesis that activation of STING can lead to the degradation of the BCR and render CLL cells more sensitive to BTKi, we propose to combine STING agonists with BTKi to treat CLL.