Alteration of the exDNA profile in blood serum of LLC-bearing mice under the decrease of tumour invasion potential by bovine pancreatic DNase I treatment

Abstract

Taking into account recently obtained data indicating the participation of circulating extracellular DNA (exDNA) in tumorigenesis, enzymes with deoxyribonucleic activity have again been considered as potential antitumour and antimetastatic drugs. Previously, using murine Lewis lung carcinoma and hepatocellular carcinoma A1 tumour models, we have shown the antimetastatic activity of bovine DNase I, which correlates with an increase of DNase activity and a decrease of exDNA concentration in the blood serum of tumour-bearing mice. In this work, using next-generation sequencing on the ABS SOLiD™ 5.500 platform, we performed a search for molecular targets of DNase I by comparing the exDNA profiles of healthy animals, untreated animals with Lewis lung carcinoma (LLC) and those with LLC treated with DNase I. We found that upon DNase I treatment of LLC-bearing mice, together with inhibition of metastasis, a number of strong alterations in the patterns of exDNA were observed. The major differences in exDNA profiles between groups were: i) the level of GC-poor sequences increased during tumour development was reduced to that of healthy mice; ii) levels of sequences corresponding to tumour-associated genes Hmga2, Myc and Jun were reduced in the DNase I-treated group in comparison with non-treated mice; iii) 224 types of tandem repeat over-presented in untreated LLC-bearing mice were significantly reduced after DNase I treatment. The most important result obtained in the work is that DNase I decreased the level of B-subfamily repeats having homology to human ALU repeats, known as markers of carcinogenesis, to the level of healthy animals. Thus, the obtained data lead us to suppose that circulating exDNA plays a role in tumour dissemination, and alteration of multiple molecular targets in the bloodstream by DNase I reduces the invasive potential of tumours.

The emerging role of cell-free DNA as a molecular marker for cancer management

“…Studies have estimated the half-life of cfDNA in circulation between 16 min and 2.5 h [ [69] , [70] , [71] ], but this requires further confirmation in various settings (e.g., healthy vs diseased; before surgery vs after surgery; at rest vs after exercise). Although the mechanisms by which cfDNA is cleared from blood remains poorly understood, it may be achieved by DNase I activity [ 72 , 73 ], renal excretion into the urine [ [74] , [75] , [76] ], and uptake by the liver and spleen followed by macrophagic degradation [ 77 , 78 ]. Clearance by these mechanisms may be further influenced by the association of cfDNA with protein complexes, extracellular vesicles, and the binding of individual cfDNA fragments to several serum proteins (e.g., Albumin, transferrin, fibrin, fibrinogen, prothrombin, globulins, C-reactive protein, HDL, Ago2, and SAA) (reviewed in [ 67 ]).…”

Extracellular DNA in natural environments: features, relevance and applications

“…Some studies also highlight the possibility to use DNase I to treat tumour cells as it targets the exDNA that facilitates the aggregation of the cells (Alekseeva et al 2017; Hawes et al 2015). During pregnancy, the entire foetal genome circulates in the maternal blood, enabling the non-invasive detection of foetal genetic disorders (Fan et al 2012).…”

“…In medical sciences, exDNA provides a useful tool for diagnostics as well as therapy monitoring, as its concentrations correlate with a variety of pathologies including cancer (Laktionov et al 2004 ) and autoimmune disorders (Raptis and Menard 1980 ; reviewed by O’Driscoll 2007 ). Some studies also highlight the possibility to use DNase I to treat tumour cells as it targets the exDNA that facilitates the aggregation of the cells (Alekseeva et al 2017 ; Hawes et al 2015 ). During pregnancy, the entire foetal genome circulates in the maternal blood, enabling the non-invasive detection of foetal genetic disorders (Fan et al 2012 ).…”

Donor-Derived Cell-Free DNA in Kidney Transplantation as a Potential Rejection Biomarker: A Systematic Literature Review

“…Unfortunately, this also requires further confirmation and must be checked under various environmental conditions and in patients in different states of health. It is known that cfDNA can enter the liver or spleen and be degraded by macrophages located inside them [ 39 ] as a result of the enzyme activity of DNase I [ 40 ], or can be removed from the body through filtration in the kidneys and excreted via urine [ 41 ]. As already mentioned, cfDNA can bind to proteins on the surface of cells and be transported to others for possible degradation or transport to the cell nucleus.…”