Zarkovic Gabriella, Ziegler Phillip, Lee Jennifer Hye-Rim, Dresden Brooke, Kumar Amit, Shuda Masahiro, Bäckerholm Alan, Shair Kathy Ho Yen
University of Pittsburgh Medical Center (UPMC) Cancer Virology Program, Pittsburgh, Pennsylvania, USA.
Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
J Med Virol. 2025 May;97(5):e70407. doi: 10.1002/jmv.70407.
Nasopharyngeal carcinoma (NPC) occurs with high incidence in Southeast Asia where almost all tumors are associated with Epstein-Barr virus (EBV) infection. Cisplatin is used in combination chemotherapy. In this study, we determined that the EBV oncoprotein, latent membrane protein 1 (LMP1), perturbs DNA damage response (DDR) signaling, activation of cell cycle checkpoints, and sensitivity to cisplatin in NPC cells (HK1). Hypersensitivity was validated by LMP1 knockdown and CRISPR/Cas9 targeting in HK1-EBV cells with latent EBV infection. The conserved PxQxT motif (in CTAR1) and Y384 residue (in CTAR2) were required for the hypersensitivity. Inhibition of ATR (VE821 or AZD6738), but not ATM (KU55933 or AZD0156), phenocopied the G1 arrest and hypersensitivity. Attenuation of DDR signaling and hypersensitivity by LMP1 or ATR inhibition was also observed in the C17 NPC cell line with restored stable LMP1 expression. LMP1 expression in NPC tumors is highly variable. Publicly available RNA-sequencing data from microdissected NPC tumors showed that LMP1 expression in the primary tumors was the lowest in cisplatin-treated patients that experienced recurrence. These findings could have clinical significance in stratifying NPC patients such that tumors with limited or variable LMP1 expression might benefit from ATR inhibitor therapy.
鼻咽癌（NPC）在东南亚地区高发，几乎所有肿瘤都与EB病毒（EBV）感染有关。顺铂用于联合化疗。在本研究中，我们确定EBV癌蛋白潜伏膜蛋白1（LMP1）会扰乱DNA损伤反应（DDR）信号传导、细胞周期检查点的激活以及NPC细胞（HK1）对顺铂的敏感性。在潜伏感染EBV的HK1-EBV细胞中，通过LMP1基因敲低和CRISPR/Cas9靶向验证了超敏反应。超敏反应需要保守的PxQxT基序（在CTAR1中）和Y384残基（在CTAR2中）。抑制ATR（VE821或AZD6738）而非ATM（KU55933或AZD0156）可模拟G1期阻滞和超敏反应。在稳定恢复LMP1表达的C17 NPC细胞系中也观察到LMP1或ATR抑制导致的DDR信号减弱和超敏反应。NPC肿瘤中LMP1的表达高度可变。来自显微切割的NPC肿瘤的公开RNA测序数据显示，在经历复发的顺铂治疗患者中，原发肿瘤中LMP1的表达最低。这些发现对于NPC患者的分层可能具有临床意义，即LMP1表达有限或可变的肿瘤可能受益于ATR抑制剂治疗。
