Understanding Epigenetics Can Help Battle Breast Cancer

For many women, the possibility of developing breast cancer is one of the most frightening health risks that they can face, and millions upon millions of healthcare dollars are poured into researching, treating and preventing this disease. Many scientists increasingly believe that improving understanding about epigenetics and breast cancer could open up significant pathways when it comes to prevention, diagnosis and treatment. But what is epigenetics?

According to Imperial College London senior research fellow Luca Magnani, “epigenetics has many definitions, but the one we like is mechanisms that regulate transmissible phenotypes that are not directly driven by changes in the sequences of protein-coding genes.” Key epigenetic features including histone modifications, DNA methylation, non-coding RNAs and chromatin structure—but while scientists now know that epigenetic dysfunction is a prime feature of many cancers including breast cancer, there is still a lot to be learned about its effects.

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Researchers believe that epigenetics plays a role in many fundamental processes within cells, including influencing gene expression. Scientists first observed that tumor cell DNA is hypomethylated compared to normal cells over three decades ago—but the fundamental question of causality still remains unanswered. As Magnani explains, “although there’s a pretty good correlation between some epigenetic marks and the gene activity state, it’s hard to conclusively say that these modifications are driving the change in transcription.”

Current theories propose that epigenetic modifications cause perturbed gene expression patterns, altering key genes involved in cancer. Key support for this hypothesis came recently when researchers pinpointed a 5’ UTR variant associated with epigenetic silencing of the BRCA1 tumor suppressor gene due to promoter hypermethylation in two families that had been affected by early-onset breast cancer. As University of Edinburgh cancer research UK career development fellow Duncan Sproul notes, “this is the closest we’ve come to a true ‘epigenetic cause’ of breast cancer, so it was quite an exciting report.”

Understanding epigenetic changes opens doors to new ways of diagnosing breast cancer, such as enabling liquid biopsies that eliminate the need for an invasive tissue biopsy. Treatment options that target aberrant epigenetic pathways also offer a lot of promise. While no such treatments have been approved for breast cancer yet, several are showing exciting potential in preclinical trials—as are those that target epigenetic modifications to overcome drug resistance in breast cancer, which can affect up to a third of breast cancer patients.

What’s more, understanding epigenetics and breast cancer better could help explain phenomena such as the association between age and breast cancer risk, helping expand breast cancer prevention options. As Magnani notes, “epigenetics is something very dynamic and so the idea of reversibility through convincing people to implement better habits could have a dramatic impact on cancer incidence.”