Medical Research Center, Genomic Medicine Institute, Seoul National University College of Medicine, Seoul, 03080, Korea.
Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea.
Mol Cancer. 2024 Aug 2;23(1):155. doi: 10.1186/s12943-024-02068-x.
Immune checkpoint therapy (ICT) provides durable responses in select cancer patients, yet resistance remains a significant challenge, prompting the exploration of underlying molecular mechanisms. Tyrosylprotein sulfotransferase-2 (TPST2), known for its role in protein tyrosine O-sulfation, has been suggested to modulate the extracellular protein-protein interactions, but its specific role in cancer immunity remains largely unexplored.
To explore tumor cell-intrinsic factors influencing anti-PD1 responsiveness, we conducted a pooled loss-of-function genetic screen in humanized mice engrafted with human immune cells. The responsiveness of cancer cells to interferon-γ (IFNγ) was estimated by evaluating IFNγ-mediated induction of target genes, STAT1 phosphorylation, HLA expression, and cell growth suppression. The sulfotyrosine-modified target gene of TPST2 was identified by co-immunoprecipitation and mass spectrometry. The in vivo effects of TPST2 inhibition were evaluated using mouse syngeneic tumor models and corroborated by bulk and single-cell RNA sequencing analyses.
Through in vivo genome-wide CRISPR screening, TPST2 loss-of-function emerged as a potential enhancer of anti-PD1 treatment efficacy. TPST2 suppressed IFNγ signaling by sulfating IFNγ receptor 1 at Y397 residue, while its downregulation boosted IFNγ-mediated signaling and antigen presentation. Depletion of TPST2 in cancer cells augmented anti-PD1 antibody efficacy in syngeneic mouse tumor models by enhancing tumor-infiltrating lymphocytes. RNA sequencing data revealed TPST2's inverse correlation with antigen presentation, and increased TPST2 expression is associated with poor prognosis and altered cancer immunity across cancer types.
We propose TPST2's novel role as a suppressor of cancer immunity and advocate for its consideration as a therapeutic target in ICT-based treatments.
免疫检查点疗法（ICT）在某些癌症患者中提供了持久的反应，但耐药性仍然是一个重大挑战，促使人们探索潜在的分子机制。已知酪氨酸蛋白硫酸转移酶-2（TPST2）在蛋白质酪氨酸 O-硫酸化中起作用，它被认为可以调节细胞外蛋白质-蛋白质相互作用，但它在癌症免疫中的具体作用在很大程度上仍未被探索。
为了探索影响抗 PD1 反应性的肿瘤细胞内在因素，我们在用人源免疫细胞移植的人源化小鼠中进行了汇集的功能丧失遗传筛选。通过评估 IFNγ 介导的靶基因诱导、STAT1 磷酸化、HLA 表达和细胞生长抑制来估计癌细胞对干扰素-γ（IFNγ）的反应性。通过共免疫沉淀和质谱鉴定 TPST2 的硫酸酪氨酸修饰靶基因。通过使用小鼠同基因肿瘤模型评估 TPST2 抑制的体内效应，并通过批量和单细胞 RNA 测序分析进行验证。
通过体内全基因组 CRISPR 筛选，TPST2 功能丧失被认为是增强抗 PD1 治疗效果的潜在增强剂。TPST2 通过在 Y397 残基上硫酸化 IFNγ 受体 1 来抑制 IFNγ 信号，而其下调则增强了 IFNγ 介导的信号和抗原呈递。在同基因小鼠肿瘤模型中，肿瘤细胞中 TPST2 的耗竭通过增强肿瘤浸润淋巴细胞增强了抗 PD1 抗体的疗效。RNA 测序数据显示 TPST2 与抗原呈递呈负相关，并且在癌症类型中，TPST2 表达增加与预后不良和改变的癌症免疫有关。
我们提出了 TPST2 作为癌症免疫抑制因子的新作用，并主张将其视为 ICT 为基础的治疗中的治疗靶点。
