In a study conducted in Mumbai, researchers found that DNA and associated proteins from dying cancer cells could enter healthy cells and induce DNA damage and inflammation. Tumour cells die after treatment and their chromatin (DNA + proteins) are released and circulated in blood. This cell-free chromatin enters nearby and even distant healthy cells and triggers DNA damage. This study was carried out by scientists from ACTREC, Tata Memorial Centre and Homi Bhabha National Institute at Mumbai and the results were recently published in Cell Death Discovery.
Healthy cells were grown alongside dying cancer cells in the lab. After six hours, the researchers were able to see chromatin from the dying cells inside the nuclei of the healthy nearby cells. There was also an increase in the levels of expressions of inflammatory proteins. The cells were then administered three chromatin-degrading or neutralising agents, which significantly reduced DNA damage. This suggests that the cell-free chromatin is the key agent that affects cells close to the tumour and neutralising agents could prevent this.
The test mice were studied after being injected with dying cancer cells. The chromatin was able to induce DNA damage and inflammation in the brain, lung and liver cells of the mice. As in the case of in vitro studies, animals treated with chromatin-degrading or neutralising agents prevented DNA damage and inflammatory reactions.
In vivo studies
“This study is the culmination of over 15 years of research which opens up an entirely new form of biology — DNA outside the cell, a new paradigm in biomedical research. Our paper suggests a re-thinking of the way we treat cancer which is to ‘kill’ cancer cells at any cost. The result may be that the more we kill, the more we may be spreading cancer,” Dr. Indraneel Mittra from Tata Memorial Centre, Advanced Centre for Treatment, Research & Education in Cancer, Mumbai and the first author of the paper says in an e-mail to The Hindu.
Current cancer treatments like radiotherapy and chemotherapy could all mobilise chromatin into the circulation thereby possibly promoting spread of cancer. This study suggests possibilities of using chromatin degrading/neutralizing agents in preventing local and systemic spread of cancer.
