Feng Ranran, Guo Yilin, Chen Meilin, Tian Ziying, Liu Yijun, Jiang Su, Zhou Jieyu, Liu Qingluan, Li Xiayu, Xiong Wei, Shi Lei, Fan Songqing, Li Guiyuan, Zhang Wenling
Department of Laboratory Medicine, The Third Xiangya Hospital, Central South University, Changsha, China.
Department of Laboratory Medicine, Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China.
J Pathol Transl Med. 2025 Jan;59(1):68-83. doi: 10.4132/jptm.2024.11.27. Epub 2025 Jan 15.
Nasopharyngeal carcinoma (NPC) is characterized by high programmed death-ligand 1 (PD-L1) expression and abundant infiltration of non-malignant lymphocytes, which renders patients potentially suitable candidates for immune checkpoint blockade therapies. Palate, lung, and nasal epithelium clone (PLUNC) inhibit the growth of NPC cells and enhance cellular apoptosis and differentiation. Currently, the relationship between PLUNC (as a tumor-suppressor) and PD-L1 in NPC is unclear.
We collected clinical samples of NPC to verify the relationship between PLUNC and PD-L1. PLUNC plasmid was transfected into NPC cells, and the variation of PD-L1 was verified by western blot and immunofluorescence. In NPC cells, we verified the relationship of PD-L1, activating transcription factor 3 (ATF3), and β-catenin by western blot and immunofluorescence. Later, we further verified that PLUNC regulates PD-L1 through β-catenin. Finally, the effect of PLUNC on β-catenin was verified by co-immunoprecipitation (Co-IP).
We found that PLUNC expression was lower in NPC tissues than in paracancer tissues. PD-L1 expression was opposite to that of PLUNC. Western blot and immunofluorescence showed that β-catenin could upregulate ATF3 and PD-L1, while PLUNC could downregulate ATF3/PD-L1 by inhibiting the expression of β-catenin. PLUNC inhibits the entry of β-catenin into the nucleus. Co-IP experiments demonstrated that PLUNC inhibited the interaction of DEAD-box helicase 17 (DDX17) and β-catenin.
PLUNC downregulates the expression of PD-L1 by inhibiting the interaction of DDX17/β-catenin in NPC.
鼻咽癌（NPC）的特征是程序性死亡配体1（PD-L1）高表达以及非恶性淋巴细胞大量浸润，这使得患者有可能成为免疫检查点阻断疗法的合适候选者。腭、肺和鼻上皮克隆蛋白（PLUNC）可抑制NPC细胞生长并增强细胞凋亡和分化。目前，在NPC中作为肿瘤抑制因子的PLUNC与PD-L1之间的关系尚不清楚。
我们收集了NPC的临床样本以验证PLUNC与PD-L1之间的关系。将PLUNC质粒转染到NPC细胞中，并通过蛋白质免疫印迹法和免疫荧光法验证PD-L1的变化。在NPC细胞中，我们通过蛋白质免疫印迹法和免疫荧光法验证了PD-L1、激活转录因子3（ATF3）和β-连环蛋白之间的关系。随后，我们进一步验证了PLUNC通过β-连环蛋白调节PD-L1。最后，通过免疫共沉淀（Co-IP）验证了PLUNC对β-连环蛋白的作用。
我们发现NPC组织中PLUNC的表达低于癌旁组织。PD-L1的表达与PLUNC相反。蛋白质免疫印迹法和免疫荧光法显示，β-连环蛋白可上调ATF3和PD-L1，而PLUNC可通过抑制β-连环蛋白的表达下调ATF3/PD-L1。PLUNC抑制β-连环蛋白进入细胞核。Co-IP实验表明，PLUNC抑制了DEAD盒解旋酶17（DDX17）与β-连环蛋白的相互作用。
在NPC中，PLUNC通过抑制DDX17/β-连环蛋白的相互作用下调PD-L1的表达。
