Two-dimensional electrophoretic analysis of human erythrocyte cylindrin

Cancer cell-intrinsic STING is associated with CD8 + T-cell infiltration and might serve as a potential immunotherapeutic target in hepatocellular carcinoma

PURPOSE

The activation of stimulator of interferon genes (STING) pathway triggers the antitumor immunity by CD8 + T cells. However, the differentiated antitumor effects of STING activation in different cell types is still unclear. We aimed to investigate the expression and potential prognostic value of cancer cell-intrinsic STING in hepatocellular carcinoma (HCC), and whether STING could be a potential immunotherapeutic target of HCC was then evaluated.

METHODS

We separately assessed the expression of STING in cancer cells and infiltrating immune cells in HCC tissues. The independent clinicopathological factors associated with survival outcomes were evaluated by the multivariable analysis. The HCC orthotopic mice model were used to confirm the immunotherapeutic effects of STING agonists, and CD8 + T-cell infiltration level was analyzed through immunofluorescence and flow cytometry.

RESULTS

The expression of cancer cell-intrinsic STING was significantly reduced in HCC compared with adjacent tissues. Patients with low levels of cancer cell-intrinsic STING expression was associated with increased tumor volume (P = 0.009), higher serum AFP levels (P = 0.028), and decreased CD8 + T-cell infiltration (P = 0.002). Low levels of cancer cell-intrinsic STING expression indicated a poor overall survival (OS) and disease-free survival (DFS). Multivariate analysis demonstrated that low levels of cancer cell-intrinsic STING expression was an independent prognostic factor. Additionally, cancer cell-intrinsic STING expression was positively related with CD8 + T-cell infiltration levels in HCC patients (r = 0.308; P = 0.001). When mice with orthotopic HCC tumors treated with STING agonists, tumor growth was significantly reduced with enhanced levels of CD8 + T-cell infiltration.

CONCLUSION

Cancer cell-intrinsic STING might affect HCC tumor progression through enhancing CD8 + T-cell infiltration and can be an immunotherapeutic target for HCC.

Isolation and partial characterization of the human erythrocyte band 7 integral membrane protein

Monoclonal antibodies to the Mr 31,000 major integral membrane protein of the human erythrocyte band 7 region were used to identify the corresponding polypeptide chain and epitope-carrying fragments on immunoblots. Analysis of the erythrocyte membrane, membrane fractions, and cytosol revealed that the Mr 31,000 band 7 integral membrane protein is unique and not related to any of the other water-soluble or membrane-bound band 7 components. Cross-reacting proteins were identified in the membranes of other mammalian erythrocytes and in cell lines of epithelial and lymphoid origin. Proteolytic digestion of intact human erythrocytes or erythrocyte membranes demonstrated that the band 7 integral membrane protein has an intracellular domain larger than Mr 12,000; it does not have an extracellular one. One of the monoclonal antibodies was employed for the isolation of band 7 integral membrane protein by immunoaffinity chromatography; subsequent Edman degradation revealed a blocked N-terminus.