Identifying Metastatic Breast Cells from Peripheral Blood
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: The early and accurate detection of metastatic breast disease would constitute a significant advance in the treatment of breast cancer. Currently, the presence of cancer in the regional lymph nodes remains the most valuable prognostic indicator for metastasis; however, as many as 30% of patients considered to be node negative eventually develop recurrent disease. Because breast cancers have been shown to shed tumor cells into the circulation soon after they become invasive, it has been proposed that detection of circulating tumor cells (CTCs) in the blood provides an index of the risk for developing distant metastases.
 
 
 
 
 
 
 
 The hypothesis of this project is that metastatic breast tumor cells circulating in the peripheral blood of breast cancer patients can be positively identified by statistical analysis of “molecule-specific images” of individual cells. We are using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to measure changes in cells that are characteristic of metastases. Metastatic progression results from altered genes, which produce altered protein products that can be measured as changes to the mass spectrum of the cell components. To provide the groundwork for later translational studies in humans, we are exploring the feasibility, sensitivity, and refinement of our approach using animal (rat) models of breast cancer.
 
 
 
 
 
 
 
 In the first CBCRP grant, we showed that differences in MTLn3 (highly metastatic) and MTC (non-metastatic) cells could be detected using principal component analysis (PCA) of ToF-SIMS spectra from single cells. These breast cancer cells were originally obtained from the same tumor, so they have a similar genetic background, but they differ in their ability to form metastases. These data demonstrate that it is possible to differentiate cells by their subtle chemical differences in disease potential. A series of objectives will be pursued in this project:
 
 1. Refine methods for the isolation of rat mammary MTLn3 and MTC cells from blood. Further develop robust molecular mass signatures for these cell types using principal component analysis.
 
 2. Prepare metastatic tumors using MTLn3 and MTC in the Fisher 344 rat; recover and quantify circulating cells from blood at several time-points.
 
 3. Use the methods developed to analyze blood samples from up to 20 women with metastatic breast cancer obtained through the UC Davis Cancer Center Specimen Repository. 
 
 
 
 
 
 
 
 We will further develop a centrifugal separation method for CTCs based on cell density and compare it to a commercial method that isolates cells using immunomagnetic beads with antibodies to epithelial cell proteins. Quantifying the recovery of cells spiked into blood will prepare us for experiments in rats implanted with xenografts to produce mammary tumors, which will shed cells into the circulation. Blood from groups of rats will be harvested at several time points, quantifying the threshold of detection of CTCs and correlating presence of cells with metastases. A major milestone will be detecting CTCs in blood samples from up to 20 women known to have metastatic breast cancer. We will begin to establish “mass spectral” criteria characteristic of metastases, and apply multivariate statistical analysis to the many cells recovered from the blood to identify metastatic cells. These experimental steps will allow us to develop a robust and reliable method for identifying metastatic breast cells circulating in peripheral blood.
 
 
 
 
 
 
 
 To this point our data demonstrates that it is possible to differentiate cells by their subtle chemical differences in disease potential. Our method will have the power of proteomic analysis with the advantage of single cell detection and could be used as the basis for a blood test for breast cancer metastasis.