This paper shows that deleting one 'TET' gene (https://en.wikipedia.org/wiki/TET_enzymes) leads to an increase in certain types of cancer. The protein encoded by that gene removes methyl (-CH3) groups from DNA, in a process called demethylation.
The 'opposite' process of methylation, in this case, is performed by the enzyme DNMT1 - and if you delete both TET and DNMT1 genes, there are less of these non-helical DNA structures and less cancer.
So the conclusion is that an imbalance between metylation and demethylation of the DNA can lead to cancer.
DNA can form structures other than just the classical 'helix' shape. For example a https://en.wikipedia.org/wiki/G-quadruplex which form at the end of the helix.
This paper shows that deleting one 'TET' gene (https://en.wikipedia.org/wiki/TET_enzymes) leads to an increase in certain types of cancer. The protein encoded by that gene removes methyl (-CH3) groups from DNA, in a process called demethylation.
The 'opposite' process of methylation, in this case, is performed by the enzyme DNMT1 - and if you delete both TET and DNMT1 genes, there are less of these non-helical DNA structures and less cancer.
So the conclusion is that an imbalance between metylation and demethylation of the DNA can lead to cancer.