Yihe Yan1,2, Leting Zheng3,4, Qiang Du3, Xiao Cui3, Kun Dong3, Yarong Guo3, David A Geller5. 1. Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. yiheyan@hotmail.com. 2. Department of General Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China. yiheyan@hotmail.com. 3. Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. 4. Department of Rheumatology and Immunology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China. 5. Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. gellerda@upmc.edu.
Abstract
BACKGROUND: CHK1 is considered an oncogene with overexpression in numerous cancers. However, CHK1 signalling regulation in hepatocellular carcinoma (HCC) remains unclear. METHODS: CHEK1 mRNA, protein, pri-miR-195 and miR-195 expression in HCC tissue was determined by qPCR, WB and IF staining assay. Survival analyses in HCC with high- and low-CHEK1 mRNA expression was performed using TCGA database. Relative luciferase activity was investigated in HCC cells transfected with p-CHEK1 3'UTR. Apoptosis was detected by TUNEL assay. NK and CD8+ T cells were analysed by flow cytometry. RESULTS: CHK1 is increased in human HCC tumours compared with non-cancerous liver. High CHK1 predicts worse prognosis. IFN-γ suppresses CHK1 via IRF-1 in HCC cells. The molecular mechanism of IRF-1 suppressing CHK1 is post-transcriptional by promoting miR-195 binding to CHEK1 mRNA 3'UTR, which exerts a translational blockade. Upregulated IRF-1 inhibits CHK1, which induces apoptosis of HCC cells. Likewise, CHK1 inhibition augments cellular apoptosis in HCC tumours. This effect may be a result of increased tumour NK cell infiltration. However, IRF-1 expression or CHK1 inhibition also upregulates PD-L1 expression via increased STAT3 phosphorylation. CONCLUSIONS: IRF-1 induces miR-195 to suppress CHK1 protein expression. Both increased IRF-1 and decreased CHK1 upregulate cellular apoptosis and PD-L1 expression in HCC.
BACKGROUND: CHK1 is considered an oncogene with overexpression in numerous cancers. However, CHK1 signalling regulation in hepatocellular carcinoma (HCC) remains unclear. METHODS: CHEK1 mRNA, protein, pri-miR-195 and miR-195 expression in HCC tissue was determined by qPCR, WB and IF staining assay. Survival analyses in HCC with high- and low-CHEK1 mRNA expression was performed using TCGA database. Relative luciferase activity was investigated in HCC cells transfected with p-CHEK1 3'UTR. Apoptosis was detected by TUNEL assay. NK and CD8+ T cells were analysed by flow cytometry. RESULTS: CHK1 is increased in human HCC tumours compared with non-cancerous liver. High CHK1 predicts worse prognosis. IFN-γ suppresses CHK1 via IRF-1 in HCC cells. The molecular mechanism of IRF-1 suppressing CHK1 is post-transcriptional by promoting miR-195 binding to CHEK1 mRNA 3'UTR, which exerts a translational blockade. Upregulated IRF-1 inhibits CHK1, which induces apoptosis of HCC cells. Likewise, CHK1 inhibition augments cellular apoptosis in HCC tumours. This effect may be a result of increased tumour NK cell infiltration. However, IRF-1 expression or CHK1 inhibition also upregulates PD-L1 expression via increased STAT3 phosphorylation. CONCLUSIONS: IRF-1 induces miR-195 to suppress CHK1 protein expression. Both increased IRF-1 and decreased CHK1 upregulate cellular apoptosis and PD-L1 expression in HCC.
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