Circulating nucleic acids damage DNA of healthy cells by integrating into their genomes.
Whether nucleic acids that circulate in blood have any patho-physiological functions in the host have not been explored.We report here that far from being inert molecules, circulating nucleic acids have significant biological activities of their own that are deleterious to healthy cells of the body. Fragmented DNA and chromatin (DNAfs and Cfs) isolated from blood of cancer patients and healthy volunteers are readily taken up by a variety of cells in culture to be localized in their nuclei within a few minutes. The intra-nuclear DNAfs and Cfs associate themselves with host cell chromosomes to evoke a cellular DNA-damage-repair-response (DDR) followed by their incorporation into the host cell genomes. Whole genome sequencing detected the presence of tens of thousands of human sequence reads in the recipient mouse cells. Genomic incorporation of DNAfs and Cfs leads to dsDNA breaks and activation of apoptotic pathways in the treated cells. When injected intravenously into Balb/C mice, DNAfs and Cfs undergo genomic integration into cells of their vital organs resulting in activation of DDR and apoptotic proteins in the recipient cells. Cfs have significantly greater activity than DNAfs with respect to all parameters examined, while both DNAfs and Cfs isolated from cancer patients are more active than those from normal volunteers. All the above pathological actions of DNAfs and Cfs described above can be abrogated by concurrent treatment with DNase I and/or anti-histone antibody complexed nanoparticles both in vitro and in vivo. Taken together, our results suggest that circulating DNAfs and Cfs are physiological, continuously arising, endogenous DNA damaging agents with implications to ageing and a multitude of human pathologies including initiation of cancer.
Translational Research Laboratory, Advanced Centre for Treatment, Research and Education in Cancer, Tata Memorial Centre, Kharghar, Navi Mumbai 410210, India, indraneel.mittra@gmail.com.
Indraneel
I
Mittra
Naveen Kumar
NK
Khare
Gorantla Venkata
GV
Raghuram
Rohan
R
Chaubal
Fatema
F
Khambatti
Deepika
D
Gupta
Ashwini
A
Gaikwad
Preeti
P
Prasannan
Akshita
A
Singh
Aishwarya
A
Iyer
Ankita
A
Singh
Pawan
P
Upadhyay
Naveen Kumar
NK
Nair
Pradyumna Kumar
PK
Mishra
Amit
A
Dutt
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002843:Chromatin / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D003850:Deoxyribonuclease I / Q000494:pharmacology; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000097:blood / Q000235:genetics; D009696:Nucleic Acids / Q000097:blood* / Q000235:genetics; D017422:Sequence Analysis, DNA
D002843:Chromatin; D006657:Histones; D009696:Nucleic Acids; C475961:gamma-H2AX protein, mouse; D004247:DNA; D003850:Deoxyribonuclease I; D053148:Caspase 3