Research Paper Volume 16, Issue 16 pp 12029—12049

Figure 8. Interaction between UBR1 and PD-L1 in Gastric Cancer. (A) The results indicated a statistically significant correlation (p < 0.05) between UBR1 and various immune checkpoint-related genes, including PD-L1, CTLA4, TNFRS, ICOS, CD80, PDCD1LG2, TIGIT, CD86, IDO2, CD40, CD244, HAVCR2, BTLA, CD28, CD40LG, CD200R1, TNFSF4, CD200, and NRP1. (B) These genes were ranked by correlation size and presented in a lollipop plot, highlighting the top five genes: CD80, PDCD1LG2, CD28, PD-L1, and HAVCR2. (C) The correlation between UBR1 and PD-L1 in stomach adenocarcinoma (STAD) was further validated using the TCGA database, showing a significant positive correlation (R = 0.314, p < 0.001). (D–G) Immune scores and responses to immunotherapy were analyzed in UBR1 low- and high-expression groups, revealing significant differences in response among different patient cohorts. (H) Immunoprecipitation assays in MGC803 cells confirmed the binding affinity between UBR1 and PD-L1 proteins. (I) Immunofluorescence assays in MGC803 cells verified the colocalization of UBR1 and PD-L1 proteins. (J) Analysis of PD-L1 protein expression in null and UBR1 knockdown cell lines (AGS and MGC803) showed decreased PD-L1 expression following UBR1 knockdown.