Ning Lou,1,* Xiangui Meng,2,* Tiexi Yu,2,* Weiquan Li,2,* Xin Lv,3,* Weiwei Han,1 Wen Xiao,2 Ying Shi2 

1Department of Urology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 2Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, People’s Republic of China; 3Department of Urology, Central Hospital of Hefeng County, Enshi, 445800, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Wen Xiao; Ying Shi, Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province, 430022, People’s Republic of China, Tel +86-17088353610, Fax +85776343, Email xiaowenx11@163.com; yingshi_whxh@hust.edu.cn

Background: Studies have found that RNA-binding proteins (RBPs) are participated in the occurrence or development of tumours. However, the role of processing of precursor family (POP family) in clear cell renal cell carcinoma (ccRCC) has not been studied yet. Here, we analyzed the expression and prognostic value of POP family in ccRCC analyzed and subsequently revealed the relationship between POP7 and immune infiltration in ccRCC patients.
Methods: POP family expression in cancer and normal tissues was analyzed in Cancer Genome Atlas pan-cancer (TCGA-pan-cancer). Kaplan–Meier (KM) survival analysis, univariable and multivariable analysis demonstrated the survival of ccRCC with POP family in Kidney Clear Cell Carcinoma (TCGA-KIRC). POP7 mRNA and protein expression were verified by Gene Expression Omnibus (GEO) data, the quantitative real-time polymerase chain reaction (qRT-PCR), and Office of Cancer Clinical Proteomics Research (CPTAC). The diagnostic ability of POP7 mRNA and protein expression was achieved with ROC curves. Gene Set Enrichment Analysis (GSEA) and TiMER2 evaluated pathogenesis role and immune infiltration of POP7in ccRCC.
Results: There is a significant difference in expression of POP family in TCGA-pan-cancer, especially in ccRCC. KM survival analysis, univariable and multivariable analysis demonstrated low expression of POP7 and was associated with poor OS and poor DFS. GEO data, the qRT-PCR, and CPTAC verified the high expression of POP7 mRNA and protein in ccRCC. ROC curves verified a valuable diagnostic ability of POP7 in mRNA and protein expression. GSEA demonstrated POP7 was associated with CD8+cells, CD4+cells, natural killer (NK) cells, and helper T (TH1) cells. TiMER2 results indicated POP7 had a positive correlation with T cell regulatory (Tregs) and myeloid-derived suppressor cells (MDSC) in ccRCC and was an immunosuppressor for ccRCC.
Conclusion: POP7 was a reliable immunosuppressor, predictor and biomarker for ccRCC.

Keywords: POP7, ccRCC, immunotherapy, prognostic indicator