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Simple Summary: The efficacy of killing human cancer cells with a modified herpes simplex virus thymidine kinase TK.007/ganciclovir (GCV) system was investigated in malignant cells of different histogenetic origin. The aim was to determine whether different histogenetic origins of cancer cells in themselves influence their reaction towards an approach of synthetic lethality, which theoretically should be toxic in a similar range independently of the cell type. Fifteen malignant human cell lines were transduced with a lentiviral vector to stably express the TK.007 gene and cell proliferation assays under GCV. Among TK.007-expressing cell lines, lymphoma and leukemia cells were more susceptible to killing than solid cancer cells, while osteosarcoma and melanoma cells exhibited an intermediate susceptibility. This study highlights that the histogenetic origin of malignant cells strongly influences their susceptibility towards cytotoxic agents, with leukemias and lymphomas being more sensitive than solid cancer cells. Background: Remarkable differences exist in the outcome of systemic cancer therapies. Lymphomas and leukemias generally respond well to systemic chemotherapies, while solid cancers often fail. We engineered different human cancer cells lines to uniformly express a modified herpes simplex virus thymidine kinase TK.007 as a suicide gene when ganciclovir (GCV) is applied, thus in theory achieving a similar response in all cell lines. Methods: Fifteen different cell lines were engineered to express the TK.007 gene. XTT-cell proliferation assays were performed and the IC50-values were calculated. Functional kinome profiling, mRNA sequencing, and bottom-up proteomics analysis with Ingenuity pathway analysis were performed. Results: GCV potency varied among cell lines, with lymphoma and leukemia cells showing higher susceptibility than solid cancer cells. Functional kinome profiling implies a contribution of the SRC family kinases and decreased overall kinase activity. mRNA sequencing highlighted alterations in the MAPK pathways and bottom-up proteomics showed differences in apoptotic and epithelial junction signaling proteins. Conclusions: The histogenetic origin of cells influenced the susceptibility of human malignant cells towards cytotoxic agents with leukemias and lymphomas being more sensitive than solid cancer cells. [ABSTRACT FROM AUTHOR]

Immunotherapeutic strategies are increasingly important in neuro-oncology, and the elucidation of escape mechanisms that lead to treatment resistance is crucial. We investigated the impact of immune pressure on the clonal dynamics and immune escape signature by comparing glioma growth in immunocompetent versus immunodeficient mice. Glioma-bearing WT and [Pd-1.sup.-/-] mice survived significantly longer than immunodeficient [Pfp.sup.-/-] [Rag2.sup.-/-] mice. While tumors in [Pfp.sup.-/-] [Rag2.sup.-/-] mice were highly polyclonal, immunoedited tumors in WT and [Pd-1.sup.-/-] mice displayed reduced clonality with emergence of immune escape clones. Tumor cells in WT mice were distinguished by an IFN-[gamma]-mediated response signature with upregulation of genes involved in immunosuppression. Tumor-infiltrating stromal cells, which include macrophages/microglia, contributed even more strongly to the immunosuppressive signature than the actual tumor cells. The identified murine immune escape signature was reflected in human patients and correlated with poor survival. In conclusion, immune pressure profoundly shapes the clonal composition and gene regulation in malignant gliomas., Introduction Glioblastoma represents the most frequent aggressive intrinsic brain tumor, and patient outcome remains uniformly fatal despite improved treatment options (1). The current era of glioblastoma therapy is being redefined [...]

Hepatocellular carcinoma (HCC) results in high mortality due to ineffective systemic therapy. Human immortalized cell lines are commonly used to study anti-tumor effects in the context of new anti-tumor therapies and tumor biology. As immortalized cell lines have limited biological relevance and heterogeneity compared to primary cells, patient-derived tumor tissues, and corresponding immune cells are the gold standards for studying the complexity of individual tumor entities. However, culturing primary HCC cells has a low success rate. Here, we aimed to establish a reproducible approach to preserve the patient-derived liver cancer cells for in vitro and in vivo studies. The underlying study aimed to establish an in vitro pre-screening platform to test treatment options' effectivity and dosage, e.g., for new substances, autologous modified immune cells, or combined therapies in HCC. We initially employed 15 surgical resection specimens from patients with different HCC entities for isolation and preservation. The isolated liver cancer cells from four HCC-diagnosed patients were used for orthotopic transplantation into the healthy liver of immunodeficient mice, allowing them to grow for six months before human liver cancer cells were isolated and cultured. As a result, we generated and characterized four new primary-like liver cancer cell lines. Compared to immortalized HCC cell lines, freshly generated liver cancer cells displayed individual morphologies and heterogeneous protein-level characteristics. We assessed their ability to proliferate, migrate, form spheroids, and react to common medications compared to immortalized HCC cell lines. All four liver cancer cell lines exhibit strong migration and colony-forming characteristics in vitro, comparable to extensively investigated immortalized HCC cell lines. Moreover, the four etiological different liver cancer cell lines displayed differences in the response to 5-FU, Sorafenib, Axitinib, and interferon-alpha treatment, ranking from non-responders to responders depending on the applicated medication. In sum, we generated individual patient-derived liver cancer cell lines suitable for predictive in vitro drug screenings and for xenograft transplantations to realize the in vivo investigation of drug candidates. We overcame the low cultivation success rate of liver cancer cells derived from patients and analyzed their potential to serve a pre-clinical model. [ABSTRACT FROM AUTHOR]