Extrachromosomal circular DNAs: an extra piece of evidence to depict tumor heterogeneity

• Published in: Future science OA Vol. 5; no. 6; p. FSO390
• Main Authors: Tandon, Ishita, Pal, Roshni, Pal, Jayanta K, Sharma, Nilesh K
• Format: Journal Article
• Language: English
• Published: England Future Science Ltd 31.05.2019; Taylor & Francis Group
• Subjects: biomarker; DNA repair; eccDNAs; epigenome; neoplasms; Review; tumor heterogeneity; tumor microenvironment; epigenome; eccDNAs; tumor microenvironment; biomarker; neoplasms; DNA repair; tumor heterogeneity
• ISSN: 2056-5623; 2056-5623
• DOI: 10.2144/fsoa-2019-0024

The tumor microenvironment (TME) comprises a heterogeneous number and type of cellular and noncellular components that vary in the context of molecular, genomic and epigenomic levels. The genotypic diversity and plasticity within cancer cells are known to be affected by genomic instability and genome alterations. Besides genomic instability within the chromosomal linear DNA, an extra factor appears in the form of extrachromosomal circular DNAs (eccDNAs; 2–20 kbp) and microDNAs (200–400 bp). This extra heterogeneity within cancer cells in the form of an abundance of eccDNAs adds another dimension to the expression of procancer players, such as oncoproteins, acting as a driver for cancer cell survival and proliferation. This article reviews research into eccDNAs centering around cancer plasticity and hallmarks, and discusses these facts in light of therapeutics and biomarker development. Currently, cancer patients are faced with difficulties with early detection, high doses of drugs, insufficient monitoring of drug efficacy, drug resistance and relapse. Tumor heterogeneity including genetic and extrachromosomal factors is known to be linked with various cancer-related problems. The presence and abundance of extrachromosomal circular DNAs in cancer patients could be harnessed to aid early detection of cancer, as well as for development of new classes of drugs/inhibitors.