4Cancer Cell Senescence Promotes Tumor Immunosuppression in Cholangiocarcinoma via GDF-15
Binbin Li, Meina Cai, Jingchun Yang, Jessica Willhite, Sumera I IlyasAbstract
Background & Objectives
Patients with cholangiocarcinoma (CCA) commonly progress within months on first-line gemcitabine/cisplatin–based therapy with immune checkpoint inhibition (ICI), consistent with the emergence of treatment-induced adaptive resistance. Cellular senescence and its secretory program (senescence-associated secretory phenotype, SASP) can remodel the tumor immune microenvironment. We hypothesized that gemcitabine/cisplatin induces tumor-cell senescence that promotes immunosuppression and progression and prioritized SASP mediators that are mechanistically linked to this phenotype.
Method
We quantified senescence and lineage markers in chemotherapy-naïve (n = 18) and gemcitabine/cisplatin treated (n = 23) human cholangiocarcinoma specimens and analyzed single-nucleus RNA sequencing in 9 human CCA tumors. In murine orthotopic CCA models, senescent tumor cells were ablated using p16 or p21 promoter restricted inducible apoptosis (ATTAC), followed by immune profiling by flow cytometry in endpoint cohorts, or tested alone and in combination with gemcitabine/cisplatin-based therapy and immune checkpoint inhibition (ICI) for survival cohorts. Conditioned media from proliferating versus senescent tumor cells were applied to bone marrow-derived macrophages (BMDMs) to assess polarization and suppression on CD8+ T-cell proliferation. SASP candidates were screened by cytokine arrays and Growth/Differentiation Factor 15 (GDF-15) was validated by expression and genetic perturbation.
Results
Senescent cells were enriched in the tumor compartment in human cholangiocarcinoma and increased after chemotherapy, as assessed by p16, p21and telomere-associated DNA foci (TAF). In mice, ablation of p16+ or p21+ senescent tumor cells reduced tumor burden, prolonged survival, and improved response to gemcitabine/cisplatin-based regimens. Chemotherapy-induced senescence increased immunosuppressive tumor-associated macrophages (TAMs), an effect reversed by senescent tumor cell ablation. Mechanically, GDF-15 was the top enriched secreted factor from senescent human CCA cells, tracked with senescence associated transcriptional programs, and decreased after senescent tumor cell ablation. GDF-15 promoted immunosuppressive macrophage phenotype switching and macrophage-mediated suppression on CD8+ T cell proliferation. In comparison, senescence-restricted GDF-15 knockdown reduced tumor growth and macrophage-mediated immunosuppression.
Conclusion
Chemotherapy-induced tumor cell senescence promotes an immunosuppressive microenvironment through GDF-15 linked macrophage remodeling. Targeting senescent tumor cells or intercepting senescence associated GDF-15 signaling may improve response to first-line therapy in CCA.