Journal of International Oncology ›› 2023, Vol. 50 ›› Issue (7): 407-412.doi: 10.3760/cma.j.cn371439-20230404-00079

• Original Articles • Previous Articles     Next Articles

RNF43 inhibits PD-L1 expression via β-catenin in melanoma cells and promotes CD8+ T cell-mediated anti-tumor immune reaction

Wu Minhang1, Sun Wenzheng2, Yu Qingzhuo2, Guo Rong2, Ye Hui3, Du Ying3, Qiu Jin2, An Huazhang2(), Cao Lili1,2,3()   

  1. 1Oncology Center,Qianfoshan Hospital,The Second Clinical College of Shandong University of Traditional Chinese Medicine,Jinan 250014,China
    2Oncology Center,The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital,Shandong Provincial University Laboratory of Clinical Immunology and Translational Medicine,Shandong Provincial Key Laboratory for Rheumatic Disease and Translational Medicine,Shandong Lung Cancer Institute, Jinan 250014, China
    3Oncology Center,Shandong Provincial Qianfoshan Hospital,School of Medicine,Shandong University,Jinan 250014,China
  • Received:2023-04-04 Revised:2023-06-03 Online:2023-07-08 Published:2023-08-03
  • Contact: Cao Lili,Email: cll@sdu.edu.cn;An Huazhang,Email: anhz@immunol.org

Abstract:

Objective To investigate the regulatory effects of ring finger protein 43 (RNF43) on CD8+ T cell-mediated anti-tumor immune reaction in melanoma. Methods RNF43 gene was over-expressed and knockdown in mouse melanoma cells line B16-OVA by lentivirus infection; In vivo proliferation of mouse melanoma cells line B16-OVA in the Lv-Ctrl-OE,Lv-RNF43-OE,Lv-Ctrl-KD and Lv-RNF43-KD groups was detected by subcutaneous tumorigenesis assay in mice,and the expression levels of CD8+ T cells perforin and interferon γ (IFN-γ) in tumor immune microenvironment of melanoma were detected by flow cytometry; The expression levels of β-catenin and programmed death-ligand 1 (PD-L1) mRNA in cells were detected by quantitative real-time PCR assay; The effect of RNF43 on the transcriptional regulation of PD-L1 was detected by dual-luciferase reporter gene assay. Results Stable RNF43 over-expressing and RNF43 knockdown mouse melanoma cells lines Lv-RNF43-OE and Lv-RNF43-KD were successfully constructed. The results of subcutaneous tumorigenesis experiment in mice showed that the tumor mass of the Lv-RNF43-OE group was (0.08±0.06) g,which was significantly smaller than that of the Lv-Ctrl-OE group [(1.04±0.52) g],with a statistically significant difference (t=3.71,P=0.032); The tumor mass of Lv-RNF43-KD group was (1.94±0.29) g,with no statistically significant difference (t=-1.70,P=0.164) compared with that of the Lv-Ctrl-KD group (1.15±0.74) g. The flow cytometry results showed that the fluorescence intensity of CD8+ T cell perforin in the Lv-RNF43-OE group was 9 034 ± 2 628,which was significantly higher than that in the Lv-Ctrl-OE group (3 847 ±1 637),with a statistically significant difference (t=-3.35,P=0.015); The fluorescence intensity of CD8+ T cell perforin in the Lv-RNF43-KD group was 966±247,which was significantly lower than that in the Lv-Ctrl-KD group (2 226±646),with a statistically significant difference (t=3.16,P=0.034); The fluorescence intensity of IFN-γ of CD8+ T cell in the Lv-RNF43-OE group was 2 422±429,which was significantly higher than that of 1 688±324 in the Lv-Ctrl-OE group,with a statistically significant difference (t=-2.73,P=0.034); The fluorescence intensity of IFN-γ of CD8+ T cell in the Lv-RNF43-KD group was 614 (454,863),with a statistically significant difference (Z=-1.96,P=0.050) compared with 1 159 (1 152,2 068) in the Lv-Ctrl-KD group. The results of quantitative real-time PCR showed that the relative expression level of β-catenin mRNA in the Lv-RNF43-OE group was 0.67±0.16,which was significantly lower than that of 1.00±0.11 in the Lv-Ctrl-OE group,with a statistically significant difference (t=2.98,P=0.041); The relative expression level of PD-L1 mRNA in the Lv-RNF43-OE group was 0.32±0.09,which was significantly lower than that of 1.00±0.09 in the Lv-Ctrl-OE group,with a statistically significant difference (t=9.13,P=0.001). The results of the dual-luciferase reporter gene assay showed that the PD-L1 promoter luciferase activity in the pCMV6-NC,RNF43,RNF43+β-catenin and β-catenin groups were 1.00±0.00,0.84±0.00,1.49±0.00 and 1.57±0.03 (F=2 218.33,P<0.001). Further pairwise comparison showed that compared with the pCMV6-NC group,PD-L1 promoter luciferase activity was significantly lower in the RNF43 group (P<0.001) and significantly higher in the RNF43+β-catenin and β-catenin groups (P<0.001; P=0.003); compared with the RNF43 group,PD-L1 promoter luciferase activity was significantly higher in the RNF43+β-catenin group (P<0.001). Conclusion RNF43 may reduce the expression of PD-L1 mRNA in melanoma by inhibiting the expression of β-catenin and promote CD8+ T cell-mediated anti-tumor immune reaction.

Key words: Melanoma, Beta catenin, Ring finger protein 43