Lukun Yang,1,2,* Ling Li,3,* Peiping Li,1,* Jiafan Chen,1 Chaonong Cai,1 Yingbin Jia,1 Jian Li,1 Baojia Zou1 

1Department of Hepatobiliary Surgery, The Fifth Affiliated Hospital of Sun Yat-Sen University, Zhuhai, Guangdong Province, People’s Republic of China; 2Department of Anesthesiology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, Guangdong Province, People’s Republic of China; 3Department of Pharmacy, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, Guangdong, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Baojia Zou; Jian Li, Department of Hepatobiliary Surgery, The Fifth Affiliated Hospital of Sun Yat-sen University, 52 Mei Hua East Road, Zhuhai, 519000, People’s Republic of China, Tel +86-756-252-8781, Fax +86-756-252-8166, Email zoubj6@mail.sysu.edu.cn; lijian5@mail.sysu.edu.cn

Purpose: Both Ku80 and Ku70 are promising drug targets for hepatocellular carcinoma (HCC) and crucial for immune regulation. However, their correlation with HCC immune signatures has not yet been investigated. Therefore, we aimed to investigate the relationship between Ku80, Ku70, and immune signatures in HCC and validate their significance in cytotoxic lymphocyte (CTL) immunotherapy.
Patients and Methods: Analyses of Ku70, Ku80, and immune signatures in public datasets was performed using R software, an online Kaplan-Meier plotter, g:Profiler, GeneTrail, and Metascape. Uniform manifold approximation and projection, correlation chord diagrams, Pearson’s correlation tests, and Spearman correlation tests were used to describe various correlation levels. HCC mRNA sequencing data (n=373 tumor samples and n=50 para-tumor samples) were drawn from The Cancer Genome Atlas (TCGA) public database. Immunofluorescent staining was used to validate Ku70/Ku80 and CD8+CTL expression in 120 HCC patients from our center. Survival analysis was performed using the Kaplan-Meier survival analysis with the Log rank test and was adopted to analyze immunotherapy outcomes correlated with Ku70/Ku80 expression in various solid tumors. Multivariate analysis of HCC patient data from our center was performed using a Cox proportional hazards model.
Results: Increased Ku70/Ku80 expression positively correlated with more enriched immune microenvironment signatures, indicating increased immune infiltration in HCC. Upregulation of Ku70/Ku80 indicated better anti-PD1 and anti-PDL1 treatment outcomes in various solid tumors. Higher Ku70/Ku80 expression with lower CD8+CTL signatures indicated worse survival outcomes, whereas lower Ku70/Ku80 expression with higher CD8+CTL signatures indicated the best prognosis.
Conclusion: Higher Ku70/Ku80 expression indicated an immune-hot infiltration signature in HCC. Patients with increased Ku70/Ku80 expression and high CD8+CTL signatures may potentially benefit from CTL-centered immunotherapies.

Keywords: hepatocellular carcinoma, XRCC6/Ku70, XRCC5/Ku80, CTL-centered immunotherapy, tumor immune microenvironment