Researchers from the Kimmel Cancer Center at Johns Hopkins have discovered evidence that genetic changes occurring outside nuclear DNA may cause more than half of all cancers. Hypermethylation - the build up of chemical bonds on certain cancer-promoting genes - has been proven to turn healthy cells cancerous by disrupting the stop growth signals built into the genes.

Now Joseph Califano, M.D., professor of otolaryngology–head and neck surgery and oncology at Johns Hopkins, and his group say the reverse process, called demethylation, may also trigger cancers at a very high rate. Particularly startling news since many treatment plans include the use of demethylating drugs to treat some cancers - a process that may be causing new tumors to form as a side effect.

“It’s much too early to say for certain, but some patients could be at risk for additional primary tumors, and we may find that they need a molecular profile of their cancer before starting demethylating therapy,” said Dr. Califano.

The findings, based on studies of normal and cancer cells from human mouth, nose and throat tissue, provide more evidence that important regulators of gene activity occur outside as well as inside DNA in a cell’s nucleus.

“While cancer-causing and other mutations alter vital protein-making pathways by rewriting the gene’s DNA code, epigenetic changes affect genes without changing the code itself. The new studies tell us that such changes occur not only when methyl groups bond to a gene’s on-off switch, but also when they come unglued,” says Califano.

The results of the findings are presented in this weeks PLoS One online journal:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0004961

Source:
http://www.hopkinskimmelcancercenter.org/index.cfm/cID/1684/mpage/item.c...