Genetic Marker Of Common Breast Tumors Found

The identification of MED12, found in 60 percent of fibroadenoma patients, could lead to better diagnosis of the common breast tumor.

AsianScientist (Jul 24, 2014) – A multi-disciplinary team of scientists have identified a critical gene that is disrupted in nearly 60 percent of fibroadenoma cases, MED12. These findings have been published in the journal Nature Genetics.

Fibroadenomas are the most common benign breast tumours in women of reproductive age, affecting thousands of women in Singapore each year. Worldwide, it is estimated that millions of women are diagnosed with fibroadenoma annually. Frequently discovered in clinical workups for breast cancer diagnosis and during routine breast cancer screening, clinicians often face of challenge of distinguishing fibroadenomas from breast cancer.

To facilitate this diagnostic question, the team embarked on a study to identify if there are any genetic abnormalities in fibroadenomas that may be used to differentiate them. By analysing all the protein-coding genes in a panel of fibroadenomas from Singapore patients, the team identified frequent mutations in a gene called MED12.

Professor Tan Puay Hoon from the Singapore General Hospital said, “It is amazing that these common breast tumours can be caused by such a precise disruption in a single gene. Our findings show that even common diseases can have a very exact genetic basis. Importantly, now that we know the cause of fibroadenoma, this research can have many potential applications.”

“For example, measuring the MED12 gene in breast lumps may help clinicians to distinguish fibroadenomas from other types of breast cancer. Drugs targeting the MED12 pathway may also be useful in patients with multiple and recurrent fibroadenomas as this could help patients avoid surgery and relieve anxiety,” she added.

The team’s findings have also deepened the conceptual understanding of how tumours can develop. Like most breast tumours including breast cancers, fibroadenomas consist of a mixed population of different cell types, called epithelial cells and stromal cells. However, unlike breast cancers where the genetic abnormalities arise from the epithelial cells, the scientists showed that the pivotal MED12 mutations are found in the stromal cells, using a technique called laser capture microdissection (LCM).

Associate Professor Steve Rozen from Duke-NUS Graduate Medical School said, “Stromal cells function to provide a supportive tissue around organs, and in breast cancers, are typically thought of as uninvolved or at least secondary bystanders in tumour formation. Our study shows that far from that, fibroadenomas and possibly other tumours may actually arise from genetic lesions in stromal cells. Targeting such stromal cells may be an important avenue for therapy in the future.”

The study also sheds light on the cause of uterine fibroids, another common benign tumour in women where similar MED12 mutations have been observed.

The scientists are already planning further studies to explore this possibility by investigating the role of MED12 in other categories of breast tumours.

The article can be found at: Lim et al. (2014) Exome Sequencing Identifies Highly Recurrent MED12 Somatic Mutations in Breast Fibroadenoma.

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Source: SingHealth.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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