Targeting a Novel Signaling Nexus pACK/pCSK/pLCK in Immune Checkpoint Blockade (ICB)-Resistant Prostate Cancer

项目摘要 前列腺癌（PC）患者虽然最初对雄激素剥夺治疗有反应，但大多数患者发展为 该抗性发展到称为去势抵抗性前列腺癌（CRPC）的阶段。前列 癌症是未观察到免疫浸润的非炎症或“免疫沙漠”肿瘤，这表明 失败发生在T细胞启动过程中的某个地方，或T细胞运输回肿瘤。不 令人惊讶的是，前列腺癌对免疫检查点阻断（ICB）疗法是高度难治的， 在临床试验中，作为单一药物或与其他药物组合的边际疗效。是如何 前列腺癌强制逃避抗肿瘤免疫应答的机制还不完全清楚。 以前，我们发现一种非受体酪氨酸激酶，ACK 1沉积了新的pY 88-H4表观遗传标记， 在AR基因增强子中，调节AR/AR-V7的表达。基于这一发现，我们开发了一种新的ACK 1 小分子抑制剂（R）-9b，其抑制恩杂鲁胺抗性肿瘤生长。检查ACk 1 进一步地，我们产生了一个可行的条件性ACK 1敲除（KO）小鼠，并注意到显着增加， 在KO小鼠中活化的CD 4+和CD 8 + T细胞中，导致同基因前列腺肿瘤生长丧失。 随后的研究揭示了ACK 1激酶在T细胞抗原启动中的关键作用 受体（TCR）信号传导通过CSK在以前未知的位点Tyr 18磷酸化。磷酸化CSK Tyr 505处的LCK促进自身抑制，抑制适应性免疫应答。因此，ACK 1 KO小鼠或 注射（R）-9b的小鼠表现出增加的CD 4+和CD 8 + T细胞活化和肿瘤生长抑制。在 此外，CRPC患者的（R）-9b功能性复苏的外周血单核细胞（PBMC）， 对CRPC类器官产生强大的免疫应答。总之，这些数据表明（R）-9b满足了预期目标。 独特的生态位，其中它不仅抑制肿瘤细胞内的AR/AR-V7，而且还激活宿主免疫 建立一个强有力的“双重”抗肿瘤反应的系统。该项目的具体目标是： 目的1：检测ACK 1介导的CSK Tyr 18磷酸化在T细胞静止中的作用 目的2：探讨pACK 1/pY 18-CSK/pY 505-LCK信号通路在抗肿瘤免疫沉默中的作用 响应 目的3：评估（R）-9b在前列腺癌模型中的治疗功效

Project Abstract Prostate cancer (PC) patient although initially respond to androgen deprivation therapy, most patients develop the resistance developing a stage referred to as the Castration Resistant Prostate Cancer (CRPC). Prostate cancer is a non-inflamed or “Immune desert” tumor where no immune infiltrate is observed, suggesting that failure has occurred somewhere in the process of T-cell priming, or T-cell trafficking back to the tumor. Not surprisingly, prostate cancer is highly refractory to immune checkpoint blockade (ICB) therapies exhibiting marginal efficacy in clinical trials, both as a single agent or in combination with other agents. Precisely how prostate cancer enforce evasion of anti-tumor immune response is not fully understood. Previously, we uncovered that a non-receptor tyrosine kinase, ACK1 deposited novel pY88-H4 epigenetic marks in AR gene enhancer, regulating AR/AR-V7 expression. Building on this discovery, we developed a new ACK1 small molecule inhibitor, (R)-9b, which suppressed enzalutamide-resistant tumor growth. To examine ACk1 signaling further, we generated a viable conditional ACK1 knockout (KO) mice, and noticed a significant increase in activated CD4+ and CD8+ T cells in KO mice, causing loss of syngeneic prostate tumor growth. The subsequent studies have revealed a crucial role for ACK1 kinase in the initiation of T cell antigen receptor (TCR) signaling by phosphorylation of CSK at a previously unknown site, Tyr18. CSK phosphorylated LCK at Tyr505 promoting auto-inhibition, inhibiting an adaptive immune response. Thus, ACK1 KO mice, or the (R)-9b injected mice exhibited increased CD4+ and CD8+ T cells activation and inhibition of tumor growth. In addition, (R)-9b functionally reinvigorated peripheral blood mononuclear cells (PBMCs) of the CRPC patients to mount robust immune response against CRPC organoids. Together, these data indicate that (R)-9b fulfills a unique niche, wherein it not only suppresses AR/AR-V7 within the tumor cells, but also activates host immune system to mount a robust `dual’ anti-tumor response. The specific aims of this project are: Aim 1: Examine roles of ACK1-mediated CSK Tyr18-phosphorylation in T cell quiescence Aim 2: Interrogate role of renewed pACK1/pY18-CSK/pY505-LCK signaling in silencing of anti-tumor immune response Aim 3: Evaluate therapeutic efficacy of (R)-9b in models of prostate cancer