Scramblase Xk-related protein 8 (Xkr8) regulates the externalization of phosphatidylserine (PS) during apoptosis and holds a pivotal role in fostering tumor immunosuppression. Targeting Xkr8 in conjunction with chemotherapy demonstrated a novel avenue for amplifying antitumor immune response and overcoming chemo-immune resistance. Here we further evaluated this strategy by using a clinically relevant orthotopic model and elucidated the mechanism through in-depth single-cell RNA sequencing (scRNA-seq). We found that Xkr8 knockdown exhibited the potential to lead to immunogenic cell death (ICD) by impeding the normal clearance of apoptotic cells. Co-delivery of Xkr8 small interference RNA (siRNA) and a prodrug conjugate of 5-fluorouracil (5-Fu) and oxoplatin (FuOXP) showed remarkable therapeutic efficacy in an orthotopic pancreatic tumor model with increased infiltration of proliferative NK cells and activated macrophages in the tumor microenvironment (TME). Single-cell trajectory analysis further unveiled that tumor infiltrating CD8 T cells are differentiated favorably to cytotoxic over exhausted phenotype after combination treatment. Our study sheds new light on the impact of Xkr8 knockdown on TME and solidifies the rationale of combining Xkr8 knockdown with chemotherapy to treat various types of cancers.

中文翻译：

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敲低 Xkr8 通过调节肿瘤免疫微环境增强化疗疗效

Scramblase Xk 相关蛋白 8 (Xkr8) 在细胞凋亡过程中调节磷脂酰丝氨酸 (PS) 的外化，并在促进肿瘤免疫抑制中发挥关键作用。靶向 Xkr8 与化疗相结合，证明了增强抗肿瘤免疫反应和克服化疗免疫耐药性的新途径。在这里，我们使用临床相关的原位模型进一步评估了这一策略，并通过深入的单细胞 RNA 测序 (scRNA-seq) 阐明了其机制。我们发现 Xkr8 敲低有可能通过阻碍凋亡细胞的正常清除而导致免疫原性细胞死亡 (ICD)。 Xkr8 小干扰 RNA (siRNA) 与 5-氟尿嘧啶 (5-Fu) 和奥索铂 (FuOXP) 的前药缀合物的共同递送在原位胰腺肿瘤模型中显示出显着的治疗效果，其中增殖性 NK 细胞和活化巨噬细胞的浸润增加。肿瘤微环境（TME）。单细胞轨迹分析进一步揭示，联合治疗后，肿瘤浸润性 CD8 T 细胞比耗尽表型更有利于分化为细胞毒性细胞。我们的研究为 Xkr8 敲低对 TME 的影响提供了新的线索，并巩固了将 Xkr8 敲低与化疗相结合来治疗各种类型癌症的基本原理。