Towards the Implementation of a Portable Magnetoresistive Point-of-Care System for Cell-Free DNA Detection in Cancer Diagnosis

摘要

The genetic profile of solid tumours is currently obtained from surgical or biopsy specimens; however, this procedure cannot always be performed routinely owing to its invasive nature. Nonetheless, tumour cells and surrounding tissues release circulating free DNA (cfDNA) into the blood that might provide insightful information about the genetic landscape of all cancerous lesions, acting therefore as a liquid biopsy. The cfDNA is originated mainly when cell death occurs, under apoptosis or necrosis. Under normal physiological conditions, infiltrating phagocytes clear apoptotic and necrotic debris and, therefore, levels of cfDNA in healthy individuals are usually low. Additionally, in this case, apoptosis is favoured over necrosis, meaning that the released cfDNA is truncated into fragments of 180-200 bp due to programmed apoptotic enzymatic activity. Conversely, in certain conditions, such as in the presence of a tumoral mass, clearance does not happen efficiently and necrosis is increased within the surrounding tissues leading to an accumulation of cellular debris, including DNA, that is then released into the blood in a less fragmented state, characteristic of a necrotic DNA fragmentation. As a consequence, the presence of a higher amount of DNA and of longer fragment sizes is hypothesized to be verified in the blood circulation of cancer patients.