Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Chen, S.
CIRCULATING TUMOR CELLS AS BIOMARKER FOR MINIMAL RESIDUAL DISEASE IN PROSTATE CANCER
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Graz Medical University; 2018. pp. 138
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Kroneis Thomas
- Petek Erwin
- Sedlmayr Peter
- Altmetrics:
- Abstract:
- Circulating tumor cells (CTCs) are released by primary tumor lesions or metastases into peripheral blood. Recently CTCs have received substantial attention because of their potential benefits for detecting cancer cell dissemination and influencing the decision for treatment. Among many recently developed techniques, the CellCollector DC01 (DC01), a medical wire functionalized with anti–epithelial cell adhesion molecule (EpCAM) antibodies, is a CE certified medical device already in clinical application. Unlike other methods which use limited volumes of blood as starting material ex vivo, the DC01 allows isolating CTCs directly from the peripheral blood circulation. Up to now, most of the studies of CTCs have been performed in metastatic cancers. Its usefulness to be an early prognostic marker in detection of minimal residual disease in patients with localized primary tumors is still unknown due to its even lower concentration in the blood, which requires advanced techniques with high sensitivity and specificity. In the first part of the result in the current thesis, 51 samples from high-risk prostate cancer (PCa) patients without metastatic setting were included for CTC detection and enumeration using two different methods, CellSearch system and DC01. Our preliminary data show that DC01 report almost twice as many patients to be CTC-positive (39.2%) as compared to the CellSearch (19.6%) with higher numbers of CTCs per patient detected by DC01 (range = 0-15) than by CellSearch (range 0-5) before undergoing radiotherapy. Paired analysis across all 86 samples (i.e. before and after therapy) showed DC01 to detect higher CTC counts than CellSearch (P = 0.0062). Statistical analysis did not reveal a correlation between CTC positivity and any of the pathological features of the included patients. Moreover, when it comes to personalized medicine, analyses exclusively based on CTC enumeration are rather insufficient. CTCs detected by DC01 cannot be recovered for the purpose of single cell analysis. Hence, a newly developed approach is introduced and we aim at retrieving captured CTCs for downstream single cell analysis. This novel so-called Catch and Release detector [CellCollector type Detektor CANCER03 (Catch & Release, C&R, GILUPI)] which currently awaits CE certification, was further evaluated. In the second part of results in the current thesis (Chapter 4), an in vitro study was performed by amplifying single cells recovered from the C&R using two strategies for single-cell whole genome amplification. Subsequently the amplification products were analyzed using comparative genomic hybridization (array-CGH) and next-generation sequencing. As a result, cells captured by the C&R device could be released with efficiencies ranging from 50% to 96%. Detached cells could be recovered at rates of 12% to 50% (recovering efficiency) for downstream analysis. Array-CGH profiles of the recovered single cells shared identical gains and losses compared to genomic DNA from bulk cells from cell culture. Using the Ion Torrent Personal Genome Machine system, several hot spot mutations which were reported frequently can be detected on recovered single cells. Data from both array-CGH and next-generation sequencing analyses indicate that DNA quality of the detached cells was not altered by the C&R procedure.