Apoptosis of circulating tumor cells in prostate cancer patients

Abstract

Background The prescence of circulating tumor cells (CTCs) in the peripheral blood of cancer patients and their frequency has been correlated with disease status. Methods In this study, CTCs were characterized by flow cytometry and fluorescence microscopy after immunomagnetic enrichment from 7.5‐ml blood samples collected from patients with prostate cancer in evacuated blood‐draw tubes that contained an anticoagulant and a preservative. Events were classified as tumor cell candidates if they expressed cytokeratin, lacked CD45, and stained with the nucleic acid dye 4,6‐diamidino‐2‐phenylindole. Results In the blood of prostate cancer patients, only few of these events were intact cells. Other CTC events appeared as damaged cells or cell fragments by microscopy. By flow cytometry, these events stained variably with 4,6‐diamidino‐2‐phenylindole and frequently expressed the apoptosis‐induced, caspase‐cleaved cytokeratin 18. Similar patterns of cell disintegration were observed when cells of the prostate line LNCaP were exposed to paclitaxel before spiking the cells into normal blood samples. Conclusions The different observed stages of tumor cell degradation or apoptosis varied greatly between patients and were not found in blood of normal donors. Enumeration of CTCs and identification of CTCs undergoing apoptosis may provide relevant information to evaluate the response to therapy in cancer patients. © 2004 Wiley‐Liss, Inc.

Circulating Melanoma Cells

“…1) and many other reported studies [33][34][35][36]54 , it is clear that positivity per se is not necessarily a prognostic indicator i.e. it is possible that not all circulating cells establish successful tissue metastases.…”

“…By contrast, active migration occurs in cells which have separated from their neighbours and actively migrate. In addition, many circulating cells are apoptotic or necrotic and are unlikely to survive immune cell destruction [33][34][35][36][37] . The question remains then, is there a phenotypic and/or genotypic difference between cells that are able to survive in the circulation and metastasise from those that cannot?…”

“…Model systems that quantify circulating cells leaving the tumour, show, in fact, that 3-4×10 6 malignant cells/day are shed per gram of tumour suggesting that millions of cells may be shed from a tumour every day 24,52,53 . Characterisation of these circulating tumour cells in patients with metastatic prostate and breast cancer indicates that they are predominantly apoptotic 37 or necrotic and unlikely to survive 34,35,36 . Furthermore, circulating cells are often sheared and destroyed as they leave the tumour and enter the circulation.…”

Monitoring and Characterization of CTC in Cancer Patients

“…Evaluation of the various errors contributing to the CTC identifi cation pointed to the ability of the operator to assign an event as a CTC as the main contributor of the error 26 . Th e presence of apoptotic CTC and CTC debris that are more frequent in patients with metastatic disease as compared to the frequency of intact CTC increases the complexity of CTC assignment 27 . In most cases these tumor related events can not be used to assess the presence or absence of treatment targets.…”

Customizing CellSearch platform

“…Moreover in these papers (4,6,7,10,11), the feasibility of the test was further assessed both in cell line spiked-samples and in ex vivo samples, by evaluating the quality of images on signal-to-background basis.…”