The Telomerase Inhibitor 6-Thio-2’-Deoxyguanosine Induced Immunogenic Death of Tumor Cells

This study focused on whether telomerase inhibitor 6-Thio-dG (6-Thio-2’-deoxyguanosine) induces ICD (immunogenic cell death) in tumor cells. The immune response characteristics of the generated ICD were revealed, which provided a basis for immunotherapy using 6-Thio-dG to induce ICD in tumor cells. Firstly, mouse melanoma B16-F10, colon cancer CT26, cervical cancer related tumor TC-1 and breast cancer 4T1 cells were treated with different concentrations of 6-Thio-dG, and the cell death and morphological characteristics were observed by microscope at different time points. The cell death was quantitatively analyzed by LDH (lactate dehydrogenase) kits. Assay kit and ELISA (enzyme-linked immunosorbent assay) were used to analyze the release of immune mediators during cell death. The migration and localization of CALR (calreticulin) to the cell membrane were investigated by immunofluorescence staining. Further, the tumor model of subcutaneously transplanted TC-1 mice was established. When the tumor grew to 4-5 mm, 6-Thio-dG was injected into the tumorbearing mice for therapeutic intervention. ELISPOT (enzyme-linked immunospot assay) and flow cytometry were used to analyze the immune response of mice cells. The release of HMGB1 (high mobility group box protein B1) in tumor tissues was detected by immunohistochemistry. The results showed that 6-Thio-dG induced the death of four kinds of tumor cells, and the death characteristics were related to cell type, drug dose and treatment time. Tumor cells induced by 6-Thio-dG promote the release of the immune-stimulating “find me” signaling molecules ATP (adenosine triphosphate) and HMGB1, as well as the inflammatory cytokine IL-1β (interleukin-1β), and the aggregation of the “eat me” signaling molecule CALR in the cell membrane. In the tumor model, 6-Thio-dG significantly inhibited tumor growth, increased the level of HMGB1 in tumor tissues, and enhanced tumor antigen-specific spleen cell response expressing IFN-γ (interferon-γ). The levels of MDSC (myeloid derived suppressor cell) in spleen cells were decreased. This study revealed that 6-Thio-dG can induce ICD of tumor cells, and enhance the anti-tumor immune response ability of T cells while killing tumor cells, providing a new idea for tumor. immunotherapy

CSTR: 32200.14.cjcb.2024.02.0003