05 July 2013
Scientists from The Institute of Cancer Research, London, have found that a gene called GNAS may help to drive the growth of some breast tumours.
Researchers discovered that the GNAS gene is over-active in a subset of breast cancers, leading to a spike in chemical signalling that can promote cancer growth.
The finding expands scientists’ understanding of how some breast cancers develop and grow – information that is increasingly being used by researchers to help devise new targeted treatments.
The new study, published in the journal Oncogene, found the GNAS gene was over expressed in approximately 10% of luminal B breast cancer, a type of breast cancer that is difficult to treat and currently has a poor prognosis for patients. The findings show this gene may contribute to the development of this type of breast cancer and that targeting it could lead to a promising new way to treat the disease.
The research was funded by Cancer Research UK and Breakthrough Breast Cancer, with additional funding from the NIHR Biomedical Research Centre at The Royal Marsden NHS Foundation Trust.
Breast cancer is a complex disease that affects about one out of every eight women. Advancements in our understanding have helped doctors to more accurately diagnose and treat this disease, but some types of breast cancer are still harder to treat than others.
The luminal subtypes A and B can be treated with anti-hormone therapies but while luminal A breast cancers have a good prognosis, luminal B cancers are associated with early relapse following anti-hormone treatment and poorer life expectancy.
In this study, scientists from The Institute of Cancer Research (ICR) investigated 14 cell lines with three common mutations of luminal B breast cancer, using a technique called RNA interference to switch off genes to determine which genes drive cancer growth.
The researchers found that in cell lines with a common mutation, amplification or too many copies of chromosome 20q, turning off GNAS had a strong effect on breast cancer cells - halting cancer growth in half of the cell lines with this amplification but showing no effect on cell lines without it.
They found that the GNAS locus in this type of breast cancer enhances the production of cyclic AMP, a chemical messenger which promoted cell signalling events that have been linked to cancer cell growth. Using drugs to target GNAS, or the cell signalling events, could therefore prove to be a promising option for future treatments.
Dr Nicholas Turner, Clinical Researcher at the ICR and Honorary Consultant Oncologist at The Royal Marsden, said: “The findings of our study are interesting from a molecular pathology perspective as it’s the first time this gene has been identified as an important factor in 20q-amplified breast cancer. Amplification of the GNAS locus leads to greater cyclic AMP production, one of the fundamental signalling messengers in our cells, which enhances downstream signalling known to drive breast cancer growth.
“The GNAS locus probably cooperates with other cancer-causing genes to drive cancer development and proliferation. This discovery adds to our understanding of this type of breast cancer but it remains to be seen whether it could lead to new therapeutic targets.”