Decoding telomerase dependency of neuroblastoma cells

• Applicants: Sandra Ackermann, Ph.D.; Professor Dr. Matthias Fischer
• Subject Area: Molecular and Cellular Neurology and Neuropathology ; Hematology, Oncology ; Pediatric and Adolescent Medicine
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429199278

Neuroblastoma is a malignant solid tumor of childhood with a broad range of clinical courses: Spontaneous regression of the tumor and its metastases or growth arrest along with terminal differentiation occurs frequently in low-risk patients, resulting in excellent long-term outcome. By contrast, patient outcome is poor in high-risk neuroblastoma, despite intensive multimodal treatment. We recently demonstrated that high-risk neuroblastoma is defined by the presence of telomere maintenance, whereas such mechanisms are absent in spontaneously regressing cases (Peifer et al., Nature 2015; Ackermann et al., Science 2018). In the majority of high-risk tumors, telomere maintenance is conferred by activation of telomerase, while alternative lengthening of telomeres is found in the remaining cases. We also observed that patients whose tumors bore activated telomerase had the poorest outcome.Based on these findings, we hypothesize that induction of telomere maintenance, and specifically induction of telomerase, is a key event in driving full malignant transformation in neuroblastoma, and that telomerase may thus represent a valuable target for personalized treatment in this malignancy. Here, we are aiming at evaluating our hypotheses by modulating telomerase activity in neuroblastoma cell lines and primary neuroblastoma cell cultures. For this purpose, we will use two complementary approaches: First, we will generate and characterize conditional TERT knock-out neuroblastoma cell lines using the CRISPR/Cas technology. This approach will allow to address the question whether malignant growth of neuroblastoma bearing TERT or MYCN alterations essentially depends on TERT expression and/or telomerase activity. Second, we will determine the effects of ectopic TERT expression in primary neuroblastoma cell cultures derived from clinical low-risk patients using lentiviral transduction. This experiment will address the question whether activation of telomerase causes full malignant transformation of low-risk neuroblastoma. We will characterize both model systems in terms of effects on proliferation, viability, clonogenic growth, telomere lengths, DNA damage, apoptosis, cell cycle, morphology, and growth in nude mice. We will also generate gene expression profiles to gain insights into the transcriptional circuits affected by TERT in cancer. In addition, we will utilize the aforementioned model systems to evaluate the on-target specificity and efficacy of telomerase inhibitors. These experiments will address the question whether the cytotoxic effect of currently available telomerase inhibitors essentially depends on TERT expression and/or the catalytic activity of telomerase. Together, we expect that our studies will provide profound insights into the functional role of telomerase in high-risk neuroblastoma development, and establish sound experimental evidence for the potential value of telomerase-targeted therapies in neuroblastoma treatment.

• DFG Programme: Research Grants