All types of cancer is caused by mutations in DNA, which cause the rapid uncontrolled cell division, thus leading to non-functional cells that can invade any part of the body, causing metastasis. Although we have known that there are certain substances of carcinogens responsible for many types of cancer, like lung cancer due to smoking or skin cancer due of exposure to sun, scientists have now discovered that there are many normal biological processes that lead to mutated genome of cancer.

Researchers have found the mutational processes that drive tumour development. These mutational processes describe most mutations found in 30 of the most common cancers. Scientists have revealed more than 20 signatures of the biological processes that mutate DNA and lead to cancer. “We have identified the majority of the mutational signatures that explain the genetic development and history of cancers in patients”,says Ludmil Alexander,first author from the Wellcome Trust Sanger Institute”, we’re now beginning to understand the complicated biological process that occur over time and leave residual mutational signatures on cancer genomes”.

Cancer cells
Cancer Cells | Credit: Dr. Cecil Fox (Photographer) [Public domain], via Wikimedia Commons
A variety of processes work together for the development of cancer, thus cancer arises from two or more of the signatures. However, different cancers have different number of mutational process e.g. 2 of the signature that arise during normal biological process are responsible for ovarian cancer and 6 for liver cancer. Some of the signatures are found in multiple cancers, while others are responsible for only one type of cancer. Out of 30,25 signatures are thought to arise from age related mutational processes.

The signature leading to breast, ovarian and pancreatic cancer caused by defects in repairing DNA due to mutations in genes BRCA1 and 2.

The researchers have also found a family of enzymes APOBECs, known to edit DNA is linked to more than half of the cancer types. These enzymes are activated in response to viral infections. The resulting signature might damage the DNA caused by enzyme’s action to protect from viruses.

If we could do something to DNA that makes such mutation impossible, cancer could be a history.