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Multicellular spheroids as an in vitro tumor model
1Ludwig Boltzmann Institute of Clinical Oncology, KH Lainz, Vienna, Austria. hamilton@netway.at
Abstract:
Multicellular spheroids (MCS) have been used as an in vitro model system of micrometastases and avascular tumor regions for studying cell adhesion-dependent resistance to cytotoxic drugs and possible reversal by chemosensitizers and adhesion-reversing agents. Multicellular drug resistance has been linked to limited accessibility of cell subpopulations, active drug efflux, quiescence of cells in deeper layers due to cell contact inhibition and adverse microenvironmental conditions like acidic extracellular pH, hypoxia and nutritional depletion. The shortcomings of MCS as a tumor model include limited knowledge of the mechanisms leading to necrosis/apoptosis of core cells, the production of an extracellular matrix (ECM) by tumor cells instead of intratumoral normal cell populations and the complex relationship of MCS parameters like size, growth regulation, synthesis of ECM components and others on the origin and pretreatment of the tumor cells and specific culture conditions.
Insights
Multicellular spheroids (MCS) model tumor drug resistance by mimicking micrometastases. Understanding MCS limitations is crucial for improving in vitro cancer research and drug development.
Area of Science:
- Oncology
- Pharmacology
- Cell Biology
Background:
- Multicellular spheroids (MCS) serve as in vitro models for tumor microenvironments, including micrometastases and avascular regions.
- MCS are utilized to study drug resistance mechanisms, particularly those dependent on cell adhesion.
- Known factors contributing to multicellular drug resistance include limited drug penetration, active drug efflux, cell quiescence, and adverse microenvironmental conditions (e.g., low pH, hypoxia).
Purpose of the Study:
- To investigate the mechanisms of cell adhesion-dependent drug resistance in multicellular spheroids.
- To explore the potential of chemosensitizers and adhesion-reversing agents in overcoming this resistance.
- To identify and address the limitations of multicellular spheroids as accurate tumor models.
Main Methods:
- Utilizing multicellular spheroids as a model system to simulate tumor micrometastases and avascular zones.
- Investigating drug resistance in relation to cell adhesion properties.
- Assessing the efficacy of chemosensitizers and adhesion-reversing agents in overcoming multicellular drug resistance.
Main Results:
- Multicellular drug resistance is associated with factors like poor drug accessibility, active drug efflux, and cell quiescence in deeper spheroid layers.
- Adverse microenvironmental conditions within spheroids, such as acidic pH and hypoxia, contribute to drug resistance.
- The study highlights limitations in current MCS models, including incomplete understanding of core cell death mechanisms and the role of extracellular matrix (ECM) production.
Conclusions:
- Multicellular spheroids offer a valuable, albeit imperfect, model for studying drug resistance in avascular tumor regions.
- Further research is needed to elucidate core cell death pathways and the influence of ECM in MCS.
- Addressing the limitations of MCS models is essential for advancing in vitro cancer drug development and chemosensitizer research.