May 14th, 2013 marked an important day for breast cancer awareness. This was the day Angelina Jolie revealed that she had undergone a preventive double mastectomy. Her decision was motivated by her positive screen for BRCA1, the “breast cancer gene,” and a family experience with cancer. She was quoted saying “I can tell my children that they don’t need to fear they will lose me to breast cancer.”
After the initial reporting frenzy died down, I came to realize that most of what I had read completely overlooked the role of BRCA1 in breast cancer. Instead, we had been bombarded with stories of Angelina’s bravery for having such an invasive procedure, and how she is an inspiration for women in the same position. In these articles, the only thing I found beyond the descriptor “breast cancer gene” is “tumour suppressor,” which doesn’t say much to those without a cancer biology background.
While I have nothing against these stories (in fact, I commend Angelina for her choice – it’s one I certainly would have trouble making), I feel like we missed a huge opportunity to draw attention to the mechanics of the disease, and how the BRCA1 gene has become integrated into current screening programs. What better time to educate when you have the world’s attention and celebrity endorsement?
With that said, here is my attempt to fill in some of the blanks about breast cancer and BRCA1.
BRCA1 is short for BReast CAncer 1, early onset (also referred to as breast and ovarian cancer susceptibility gene 1), and is associated with heritable breast and (rarely) ovarian cancers. A quick note about gene nomenclature: genes are often named based on the clinical or biological role first identified or most commonly associated with that gene. So while BRCA1 is primarily associated with breast cancer, that doesn’t mean it doesn’t have other roles in cancer or normal biology.
In fact, the BRCA1 gene encodes for a protein whose normal function is a tumour suppressor – a class of protein that regulates cell division. Another note about nomenclature: as each protein is made based on the ‘blueprint’ of its corresponding gene (via processes of transcription and translation) genes and proteins often share the same name/symbol; therefore, to refer to the gene, we use italics, and the protein is written in regular text. Different tumour suppressor proteins will act through different mechanisms to accomplish their regulatory tasks. .
BRCA1 regulates cell division through its involvement in DNA repair. When cells have damaged DNA, BRCA1 participates in repairing double-strand breaks (both strands of the DNA helix are damaged) with a complex of other proteins, while also preventing the cell in question from progressing through the cell cycle. For a detailed scientific review of BRCA1 and DNA repair and cell cycle regulation, go here; for more information on double-strand break repair, look here.
The cancer-causing part of BRCA1 is not from the protein itself (in fact, as described above, you want it around), but rather, when there is a mutation in the gene’s DNA. Depending on where in the gene the mutation occurs, the BRCA1 protein may not be made, or the produced protein is dysfunctional – either way, it can no longer do its job. The problem now becomes that cells that would normally be prevented from dividing because of BRCA1, are allowed to divide, propagating their mutation(s). Over time, these mutated cells can accumulate, and may develop into a tumour mass.
I was surprised to see just how much I didn’t know about the role of BRCA1 in cancer. There’s a wealth of information out there, if you’re willing to look beyond the compelling stories about the struggles (and successes) of women diagnosed with or at risk of hereditary breast cancer. While much of what I have written may be too complicated for the tabloids that covered Angelina’s story, I think it could be an important tool for women in similar positions; to make difficult choices we need to feel in control, and knowledge is empowering.
Author’s note: stay tuned for a follow-up post on BRCA1 screening, and associated social implications. (Updated March 4, 2014 to include link.)