Medizinische Universität Graz - Research portal
Selected Publication:
Kroell, M.
Modeling NF1 loss-of-function mutation in hormone receptor-positive breast cancer cells
Humanmedizin; [ Diplomarbeit ] Medizinische Universität Graz; 2024. pp.
- Authors Med Uni Graz:
- Advisor:
- Balic Marija
- Dengler Michael
- Altmetrics:
- Abstract:
- Metastatic breast cancer remains an incurable disease and accounts for the majority of cancer-related deaths in women worldwide. The most common subtype are hormone- receptor-positive tumors, characterized by a dependence on the female sex hormones estrogen and progesterone. Implicitly, endocrine therapy is the standard of care complemented by CDK4/6 inhibitors that induce a cell cycle arrest and impede tumor cells from growing. However, therapy resistance and consecutive tumor progression remain significant clinical problems and therefore, the currently most promising research projects are translational approaches to understand therapy resistance mechanisms better and find novel targets to improve therapy options steadily. To demonstrate the current practice of translational research, a liquid biopsy-based detection of an NF1 mutation in a stage four breast cancer patient with progressive disease treated at our university hospital led to the start of an in vitro project. Therefore, we introduced an NF1 mutation with CRISPR/Cas 9 genome editing in hormone-receptor-positive MCF-7 breast cancer cells and evaluated the response of the mutated cells to standard first-line CDK4/6 inhibitors (abemaciclib, palbociclib, and ribociclib) as well as the endocrine therapy agent fulvestrant. The main focus of our experiments was directed at cell cycle alterations. In order to put our findings into perspective, we also generated a retinoblastoma protein 1 (RB1)- deficient MCF-7 cell line since RB1-loss-of function is linked to primary CDK4/6 inhibitor resistance and, therefore, the ideal positive control in our therapy resistance study. Our NF1-deficient cells grew significantly faster and showed a decreased sensitivity to CDK 4/6 inhibitors in our drug treatment experiments seen in cell-cycle alterations and a decreased extent of the CDK4/6 induced senescent-like phenotype. Interestingly, we also observed that our NF1 mutated cells preserved their highest sensitivity to the CDK4/6 inhibitor ribociclib. Expectedly, RB1 loss-of-function resulted in a cross-resistance to all three CDK4/6 inhibitors, rapid growth, and an epithelial to mesenchymal transition of their cellular state. The model developed in this thesis allows us to study the role of genetic alterations detected by dynamic liquid biopsy findings in vitro to better understand and eventually overcome therapy resistance mechanisms in the future.