Highly aggressive breast cancers show stem-cell like properties

Triple negative breast cancer (TNBC) is characterized by the absence of three main proteins that are amplified in other types of breast cancer: the estrogen receptor, the progesterone receptor and the human epidermal growth factor 2 receptor (HER2). As a result, hormonal therapies and receptor-targeted therapies cannot be used to treat this cancer subtype. Chemotherapy and other standard cancer treatment regimens are employed for treatment.

TNBC has poor prognosis due to high rates of relapse, where a tumour that was once thought to have been treated, begins to grow again. Relapse is not seen in all TNBCs, however at present, there are no reliable methods of determining which tumours have been effectively exterminated and which have not.

Breast cancer

Mammogram of breast cancer. Source: Wikimedia Commons

Adult stem cells are cells that have not yet specialized into specific cell types and can continue dividing and replace damaged cells in any other part of the body. Researchers from The Institute of Cancer Research in London, King’s College London and Cardiff University hypothesized that tumours that relapsed could have stem cell-like properties that would enable them to self-renew in patients. “Cancer cells can behave very much like stem cells – but stem cells gone bad. They find a way to activate genes which are usually only turned up in normal stem cells, giving them characteristics – such as self-renewal and immortality – that make them more difficult to treat.”, said Professor Clare Isacke, study co-author from The Institute of Cancer Research.

The study, published in Breast Cancer Research, identified 323 genes that were highly expressed in normal mouse mammary stem cells and compared this with the genetic profiles of tumours from 579 women affected with TNBC.

Based on this comparison, the scientists divided the tumours into two categories – TNBCs that had high levels of stem cell genes and those that had lower levels. Tumours of the former category were more likely to be aggressive and women with this type of tumour, showed a 10% chance of avoiding relapse after 10 years as compared to those from the latter group, where women had a 60% chance of avoiding relapse.

The authors of the study will now be working on identifying which of those 323 genes are most essential for tumour growth and proliferation and developing robust techniques to detect relapse potential in TNBCs.

The original publication can be accessed here.

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