Equipe 11 labellisée par la Ligue contre le Cancer, Université de Paris Cité, Sorbonne Université, Centre de Recherche des Cordeliers, INSERM UMR1138, Paris, France.
Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France.
J Immunother Cancer. 2022 Jun;10(6). doi: 10.1136/jitc-2021-004280.
High activity of poly(ADP-ribose) polymerase-1 (PARP1) in non-small cell lung cancer (NSCLC) cells leads to an increase in immunohistochemically detectable PAR, correlating with poor prognosis in patients with NSCLC, as well as reduced tumor infiltration by cytotoxic T lymphocytes (CTLs). Intrigued by this observation, we decided to determine whether PARP1 activity in NSCLC cells may cause an alteration of anticancer immunosurveillance.
Continuous culture of mouse NSCLC cells in the presence of cisplatin led to the generation of cisplatin-resistant PAR clones. As compared with their parental controls, such PAR cells formed tumors that were less infiltrated by CTLs when they were injected into immunocompetent mice, suggesting a causative link between high PARP1 activity and compromised immunosurveillance. To confirm this cause-and-effect relationship, we used CRISPR/Cas9 technology to knock out PARP1 in two PAR NSCLC mouse cell lines (Lewis lung cancer [LLC] and tissue culture number one [TC1]), showing that the removal of PARP1 indeed restored cisplatin-induced cell death responses.
PARP1 knockout (PARP1) cells became largely resistant to the PARP inhibitor niraparib, meaning that they exhibited less cell death induction, reduced DNA damage response, attenuated metabolic shifts and no induction of PD-L1 and MHC class-I molecules that may affect their immunogenicity. PAR tumors implanted in mice responded to niraparib irrespective of the presence or absence of T lymphocytes, suggesting that cancer cell-autonomous effects of niraparib dominate over its possible immunomodulatory action. While PAR NSCLC mouse cell lines proliferated similarly in immunocompetent and T cell-deficient mice, PARP1 cells were strongly affected by the presence of T cells. PARP1 LLC tumors grew more quickly in immunodeficient than in immunocompetent mice, and PARP1 TC1 cells could only form tumors in T cell-deficient mice, not in immunocompetent controls. Importantly, as compared with PAR controls, the PARP1 LLC tumors exhibited signs of T cell activation in the immune infiltrate such as higher inducible costimulator (ICOS) expression and lower PD-1 expression on CTLs.
These results prove at the genetic level that PARP1 activity within malignant cells modulates the tumor microenvironment.
非小细胞肺癌 (NSCLC) 细胞中聚（ADP-核糖）聚合酶-1 (PARP1) 的高活性导致免疫组织化学可检测的 PAR 增加，与 NSCLC 患者的预后不良以及细胞毒性 T 淋巴细胞 (CTL) 对肿瘤的浸润减少相关。受此观察结果的启发，我们决定确定 NSCLC 细胞中的 PARP1 活性是否会导致抗癌免疫监视的改变。
在顺铂存在的情况下连续培养小鼠 NSCLC 细胞，导致产生顺铂耐药的 PAR 克隆。与它们的亲本对照相比，当将这些 PAR 细胞注射到免疫功能正常的小鼠中时，它们形成的肿瘤 CTL 浸润较少，表明高 PARP1 活性与免疫监视受损之间存在因果关系。为了证实这种因果关系，我们使用 CRISPR/Cas9 技术敲除了两种 PAR NSCLC 小鼠细胞系（Lewis 肺癌 [LLC] 和组织培养 1 号 [TC1]）中的 PARP1，结果表明 PARP1 的缺失确实恢复了顺铂诱导的细胞死亡反应。
PARP1 敲除 (PARP1) 细胞对 PARP 抑制剂尼拉帕利（niraparib）的耐药性大大提高，这意味着它们的细胞死亡诱导减少，DNA 损伤反应减弱，代谢转换减弱，PD-L1 和 MHC Ⅰ类分子的诱导减少，这些可能会影响它们的免疫原性。植入小鼠的 PAR 肿瘤对尼拉帕利有反应，无论是否存在 T 淋巴细胞，这表明尼拉帕利的癌细胞自主作用超过了其可能的免疫调节作用。虽然 PAR NSCLC 小鼠细胞系在免疫功能正常和 T 细胞缺陷小鼠中增殖相似，但 PARP1 细胞受 T 细胞的存在强烈影响。PARP1 LLC 肿瘤在免疫缺陷小鼠中比在免疫功能正常的小鼠中生长得更快，而 PARP1 TC1 细胞只能在 T 细胞缺陷小鼠中形成肿瘤，而不能在免疫功能正常的对照小鼠中形成肿瘤。重要的是，与 PAR 对照相比，PARP1 LLC 肿瘤在免疫浸润中表现出 T 细胞激活的迹象，例如诱导共刺激因子 (ICOS) 的表达更高，CTL 上的 PD-1 表达更低。
这些结果从遗传水平证明了恶性细胞内的 PARP1 活性调节了肿瘤微环境。
