In vivo CRISPR screens in Head and Neck Cancer reveal that Uchl5 modulates extracellular matrix deposition to promote immune evasion [in vitro]

Recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with a high unmet need for enhancing immunotherapy given current modest responses. Here, we performed an in vivo CRISPR screen in a HNSCC mouse model to identify immune evasion genes. We identified several epigenetic regulators of immune checkpoint blockade (ICB) response, including the ubiquitin C-terminal hydrolase 5 (UCHL5). Loss of Uchl5 in tumors increased CD8+ T cell infiltration and improved ICB responses. Uchl5 deficiency reduced extracellular matrix (ECM) production and epithelial-mesenchymal-transition (EMT) transcriptional signatures, which contribute to stromal desmoplasia, a histologic finding associated with reduced anti-PD1 response in human HNSCCs. We identified a functional role for COL17A1, a collagen highly and specifically expressed in HNSCC, in Uchl5-mediated immune evasion. Our findings suggest an unappreciated role for UCHL5 in promoting EMT in HNSCC and highlight ECM modulation as a strategy to improve immunotherapy responses. The preclinical murine oral carcinoma MOC1-esc1 cell line (sgCtrl and sgUchl5) were treated for 24h with either DMSO or 10ng/ml IFNγ. Cells were collected for RNA-seq after 24h treatment.

复发/转移性头颈部鳞状细胞癌（Recurrent/metastatic head and neck squamous cell carcinoma, HNSCC）是一类侵袭性恶性肿瘤，鉴于当前免疫治疗应答有限，该疾病的免疫治疗优化存在极高的未被满足的临床需求。本研究在头颈部鳞状细胞癌小鼠模型中开展体内CRISPR筛选，以鉴定免疫逃逸相关基因。我们鉴定出多个调控免疫检查点阻断（immune checkpoint blockade, ICB）应答的表观遗传调控因子，其中包括泛素C末端水解酶5（ubiquitin C-terminal hydrolase 5, UCHL5）。肿瘤中Uchl5基因缺失可增加CD8+ T细胞浸润，并改善免疫检查点阻断治疗应答。Uchl5基因缺失会减少细胞外基质（extracellular matrix, ECM）生成与上皮间质转化（epithelial-mesenchymal-transition, EMT）相关转录特征，而这些特征可促成间质结缔组织增生；该组织学表型与人类头颈部鳞状细胞癌对抗PD-1治疗的应答降低密切相关。我们还明确了胶原蛋白17A1（COL17A1）在Uchl5介导的免疫逃逸中的功能作用，该胶原蛋白在头颈部鳞状细胞癌中呈高特异性表达。本研究结果表明，UCHL5在头颈部鳞状细胞癌的上皮间质转化过程中存在此前未被认知的调控作用，并揭示了通过调控细胞外基质改善免疫治疗应答的潜在策略。本研究对临床前小鼠口腔癌MOC1-esc1细胞系（分为sgCtrl组与sgUchl5组）分别施以二甲基亚砜（DMSO）或10ng/ml干扰素γ（IFNγ）处理，处理时长为24小时；处理结束后收集细胞用于RNA测序（RNA-seq）。