title: Characterization of the cell-free DNA released by cultured cancer cells.
abstract: The most prominent factor that delays the translation of cell-free DNA (cfDNA) analyses to clinical practice is the lack of knowledge regarding its origin and composition. The elucidation of the former is complicated by the seemingly random fluctuation of quantitative and qualitative characteristics of cfDNA in the blood of healthy and diseased individuals. Besides methodological discrepancies, this could be ascribed to a web of cellular responses to various environmental cues and stressors. Since all cells release cfDNA, it follows that the cfDNA in the blood of cancer patients is not only representative of tumor derived DNA, but also of DNA released by healthy cells under different conditions. Additionally, cfDNA released by malignant cells is not necessarily just aberrant, but likely includes non-mutated chromosomal DNA fragments. This may cause false positive/negative results. Although many have acknowledged that this is a major problem, few have addressed it. We propose that many of the current stumbling blocks encountered in in vivo cfDNA studies can be partially circumvented by in vitro models. Accordingly, the purpose of this work was to evaluate the release of cfDNA from cultured cells and to gauge its potential use for elucidating the nature of cfDNA. Results suggest that the occurrence of cfDNA is not a consequence of apoptosis or necrosis, but primarily a result of actively secreted DNA, perhaps in association with a protein complex. This study demonstrates the potential of in vitro cell culture models to obtain useful information about the phenomenon of cfDNA.
authors.affiliation: Centre for Human Metabolomics, Biochemistry Division, North-West University, Potchefstroom 2520, South Africa. Electronic address: abel.bronkhorst29@gmail.com.
authors.forename: Abel Jacobus
authors.initials: AJ
authors.lastname: Bronkhorst
authors.affiliation: Centre of Excellence for Pharmaceutical Sciences (PHARMACEN), North-West University, Potchefstroom 2520, South Africa.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Wentzel
authors.affiliation: Centre for Human Metabolomics, Biochemistry Division, North-West University, Potchefstroom 2520, South Africa.
authors.forename: Janine
authors.initials: J
authors.lastname: Aucamp
authors.affiliation: Centre for Human Metabolomics, Biochemistry Division, North-West University, Potchefstroom 2520, South Africa.
authors.forename: Etresia
authors.initials: E
authors.lastname: van Dyk
authors.affiliation: Centre of Excellence for Pharmaceutical Sciences (PHARMACEN), North-West University, Potchefstroom 2520, South Africa.
authors.forename: Lissinda
authors.initials: L
authors.lastname: du Plessis
authors.affiliation: Centre for Human Metabolomics, Biochemistry Division, North-West University, Potchefstroom 2520, South Africa.
authors.forename: Piet J
authors.initials: PJ
authors.lastname: Pretorius
mesh_terms: D045744:Cell Line, Tumor; D004273:DNA, Neoplasm / Q000378:metabolism*; D006801:Humans; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D004273:DNA, Neoplasm
keywords: Apoptosis; Cell-free DNA (cfDNA); Flow cytometry; Necrosis; Osteosarcoma