Epigenetic Modification Implicated in Some Adult Cancers

Scientists at the Research Institute of the McGill University Health Centre (RI-MUHC) have identified an epigenetic modification which could contribute to 15 percent of all adult cases of throat cancer. The study could help researchers develop more effective treatments for patients with head and neck cancer linked to alcohol and tobacco use.

“This discovery was absolutely unexpected,” said Dr. Nada Jabado, senior author on the publication, “since it seemed highly improbable that the kind of alterations of the epigenome that we had previously found in other types of tumors in children and young adults could also target an epithelial tumor like throat cancer that occurs only in adults.”

Currently, head and neck cancers are treated using a mix of surgery, radiotherapy and chemotherapy. However, these treatments all carry unpleasant side effects, and patients often relapse.

The discovery of the epigenetic modification could represent a new drug target for head and neck cancers. The research was published in the journal, Nature Genetics.

“Now that we’ve identified this cohort of patients, we can move quite quickly since in the case of adults, as opposed to children, there are more patients and lots of clinical trials,” said Jabado. “The medicines could then be tested on children afterward.”

Jabado and her team have a special research focus on pediatric cancer, and the epigenetic modifications associated with such malignancies. In particular, they focus on modifications affecting histone H3 – a protein that affects the organization and expression of DNA.

When it comes to research involving the epigenetics of cancer, access to large subsets of patient data is imperative. For the current study, the researchers used the same data on head and neck cancer that was published by the Tumor Cancer Genome Atlas Consortium (TCGA).

“We made use of the same data but took a completely different approach,” said Dr. Jacek Majewski, a researcher at McGill University and an author of the study. “Instead of concentrating on genetic mutations, we looked at the effect of these mutations on histone H3 proteins. That’s when we discovered that the histone H3 protein was abnormal or incorrectly modified in about 15% of patients with head and neck cancer. The data were there, but this fact had gone unnoticed.”

“It’s crucial to have access to public data, because it allows us to advance faster and go further in our analyses,” said Jabado. “In our case, this discovery revealed a sub-group of patients who might benefit from a therapy that targets the epigenome. This could improve the treatment of more than one in five patients suffering from devastating oropharyngeal cancer. We are currently collaborating with two big groups specializing in head and neck cancer with the goal of finding treatments.”