Mechanical phenotyping of cancer stemness in colorectal cancer
[eng] In this thesis work, I explored the link between cancer stemness and the mechanical properties of colorectal cancer (CRC) cells. In the last decades, the cancer stem cell (CSC) model underwent an important paradigm shift, from a static and intrinsic concept of CSCs to a more dynamic and plasti...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/223212 |
| Acceso en línea: | https://hdl.handle.net/2445/223212 http://hdl.handle.net/10803/695225 |
| Access Level: | acceso abierto |
| Palabra clave: | Càncer colorectal Cèl·lules mare Metàstasi Colorectal cancer Stem cells Metastasis |
| Sumario: | [eng] In this thesis work, I explored the link between cancer stemness and the mechanical properties of colorectal cancer (CRC) cells. In the last decades, the cancer stem cell (CSC) model underwent an important paradigm shift, from a static and intrinsic concept of CSCs to a more dynamic and plastic notion, integrating the influence of the microenvironment. Similarly, during the last five years, my experimental approach had to shift, from assuming that cancer stem cells are static and thus won’t change in response to different culture conditions, to the realization that their stemness is largely affected by the microenvironment, and thus I had to establish the experimental conditions that would maintain the desired cellular phenotypes. This effort is not reflected in the present work, but it constitutes its foundation. CRC tumors are composed of heterogeneous cell populations including a pool of cancer stem cells (CSCs) that express LGR5. The link between cancer cell differentiation states and their metastatic potential has been the focus of extensive investigation, with some studies pointing to microenvironmentally defined plasticity as a mechanism indispensable for metastasis formation. In this highly heterogeneous and plastic context, differences in mechanical phenotypes may favor or impair the ability of specific cell populations to progress through the metastatic cascade. However, whether distinct cell populations in CRC tumors display different mechanical properties, and how these properties might contribute to metastasis is unknown. In the present study I performed a broad biophysical characterization of CRC patient derived organoids (PDOs) engineered to fluorescently label cells expressing LGR5. I found that LGR5+ and LGR5- cells display distinct mechanical phenotypes. Compared to LGR5- cells, LGR5+ cells are stiffer, adhere better to the extracellular matrix (ECM), move slower both as single cells and clusters, display higher nuclear YAP, and show a higher survival rate in response to mechanical confinement. These differences are largely explained by the downregulation of the membrane to cortex attachment proteins Ezrin/Radixin/Moesin (ERMs) in the LGR5+ cells. By analyzing scRNA-seq expression patterns from a patient cohort, I show that this downregulation is a robust signature of colorectal tumors. Finally, I also show that LGR5+ cells adhere better to the endothelial surface and form transendothelial gaps with higher efficiency than LGR5- cells. Together, these results show that LGR5- cells display a mechanically dynamic phenotype that favors dissemination from the primary tumor whereas LGR5+ cells display a mechanically stable and resilient phenotype that promotes extravasation and metastatic growth. The observed coupling between mechanical states and cancer cell heterogeneity may be an indispensable adaptive mechanism for metastatic progression. |
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