The main purpose of the B2B device is to follow and dissect the steps of the metastatic process. Therefore, once some cancer cells have left the primary site, we aim to isolate and analyze their features. The main problem during this phase is that within the samples the metastatic cells are rare. “We are talking probably about less than a hundred cells – therefore, we need tools capable to detect and isolate such a small amount.”
The solution is to label the cancer cells before their insertion into the chamber. The labeling can be done with a fluorescent protein (GFP, RFP, etc.) or a luciferase – a protein found in fireflies that is responsible for their ability to emit light. According to Prof. Aceto “Such method allows us to isolate the tumor cells found in samples taken from the circulation of the B2B device. The situation is harder within the bone tissue due to the complexity of the environment. But even then, using microscopic imaging, we can recognize the metastatic cells among the bone ones thanks to their fluorescence or luminescence.”
In the isolated cancer cells, we plan to study the expression levels of some protein markers. In this way we can address specific questions; e.g. in order to understand if the cells are still proliferating while they go through the circulation, we can stain the samples with antibodies that detect proliferation markers. The limitation of this approach is that it relies on a group of pre-selected markers. To obtain a more general characterization of the metastatic cells we plan to perform a whole transcriptome analysis. The sequencing of the RNAs provides a snapshot about which genes are expressed by a cell in a particular moment and their level of expression. By comparing these expression profiles with the ones found in non-metastatic cells (the ones that remain in the primary tumor), we can identify molecular signals that might be responsible for the metastatic behavior. The same information can also be used to infer something about the microenvironment or stresses that have generated such behavior. This knowledge will guide us in the selection of the type of drugs to test as metastatic inhibitors (link to 3rd news – see below).