射频消融治疗对肝癌组织PD-L1表达的影响与调控机制

Radiofrequency ablation (RFA) is an important treatment for patients with small hepatocellular carcinoma (HCC) with similar long term prognosis to surgical resection. However some patients trend to recurrence/metastasis after treatment and the underlying reasons and mechanisms remain unclear. Our previous studies revealed that: high PD-L1 expression is significantly related to poor clinical outcomes for patients with HCC after resection; PD-L1 promotes tumor progression by inducing immune tolerance and T cell differentiation; and PD-L1 expression is significantly increased after RFA treatment in clinical samples and mouse tumor models. So we hypothesize that the local microenvironment changes caused by RFA treatment would up-regulate PD-L1 expression; and high PD-L1expression would induce tumor immune escape and promote tumor recurrence/metastasis. In this study, by using RFA mouse tumor model, in vitro cell experiments and clinical samples, we are going to do: 1) to demonstrate the local microenvironment changes after RFA and its relationships with PD-L1 expressions in different immune cell subsets; 2 ) to reveal the underlying mechanisms and regulation networks for up-regulation of PD-L1 after RFA; 3) to explore the impact of PD-L1 expression on prognosis after RFA treatment, and the feasibility of combined anti-PD-L1 treatment and RFA to prevent/reduce recurrence/metastasis. The results will help us to make clear the effect of RFA on tumor local immunologic microenvironment and the feasibility of targeting PD-L1 treatment as an adjuvant therapy to prevent/reduce tumor recurrence/metastasis after RFA.

射频消融（RFA）是肝癌重要治疗手段之一，但部分患者术后易于复发/转移，其机制尚不清楚。我们前期研究发现：PD-L1表达与肝癌患者临床预后呈显著负相关；PD-L1可通过诱导免疫耐受和T细胞亚群分化来促进肿瘤进展；临床样本和小鼠模型中均显示RFA后的肝癌组织中PD-L1表达增高。我们推测：RFA导致的肿瘤局部微环境改变可上调PD-L1的表达，从而诱导免疫逃逸，导致肿瘤复发/转移。以此为基础，本研究拟利用小鼠肝癌RFA模型，体外实验和临床样本系统研究：1）RFA对肝癌免疫微环境组成的改变及其与不同细胞亚群PD-L1表达的关系；2）阐明RFA引起PD-L1表达改变的机制和潜在调控网络；3）探讨PD-L1表达对RFA疗效的影响以及RFA联合抗PD-L1治疗的临床可行性。研究结果将帮助我们更好的了解RFA对肿瘤免疫微环境的影响，为靶向PD-L1作为降低/预防RFA后复发/转移的新防治方案提供理论基础

射频消融（RFA）是肝癌重要治疗手段之一，但部分患者术后易于复发/转移，其机制尚不清楚。基于前期研究发现，我们推测：RFA导致的肿瘤局部微环境改变可上调PD-L1的表达，从而诱导免疫逃逸，导致肿瘤复发/转移。我们首先检测了肝癌免疫微环境PD-L1的表达情况，发现肿瘤细胞和巨噬细胞是主要表达PD-L1的细胞。生存分析发现肝癌患者肿瘤细胞表达PD-L1提示不良预后，而Mϕ表达PD-L1则指示更好的临床预后。表达谱芯片分析发现肝癌组织巨噬细胞表达PD-L1与“热”肿瘤微环境相关，具有更高的免疫浸润以及更高水平的免疫活化相关基因的表达。此外，我们还建立了小鼠肝癌RFA治疗模型，检测分析发现RFA治疗后肿瘤细胞PD-L1表达水平呈上升趋势，而其他间质免疫细胞PD-L1表达水平未见明显变化。进一步分析发现，RFA治疗能够显著的激活T细胞抗肿瘤免疫应答反应，且RFA治疗联合抗PD-L1治疗能够进一步提高疗效。以上所得结果揭示了肝癌免疫微环境中PD-L1的表达模式及其临床意义，并且探究了RFA治疗对PD-L1的影响，将有助于为临床筛选适合anti-PD1/PD-L1治疗的肝癌患者，并有望为RFA联合anti-PD1/PD-L1治疗方案提供理论基础。