Washington: A new study has identified a genetic ‘switch’ in breast cancer cells that facilitates the production of internal scaffolding, a type of protein called Keratin-80, which makes cancer cells more rigid and may make the cells travel in bloodstream to other parts of the body.
The study published in ‘Nature Communications’ has found that the same switch is involved in breast cancer cells becoming resistant to the medication.
Targeting this switch with a different drug could help reverse this resistance, and make cancer less likely to spread, explained Dr Luca Magnani, lead author of the study.
“Till now we didn’t know the reasons behind this, but our early-stage study suggests a type of genetic switch — called a transcription factor — can turn on genes that cause the cancer cells to not only become resistant to the treatment but move into healthy tissue around the body,” said Dr Magnani.
According to the study, the switch that turns on genes that increase cholesterol production also activates genes that make the cells more rigid and prone to invade nearby tissues.
The team also found that in women whose cancers had spread around the body, the cells contained higher amounts of Keratin-80.
“Aromatase inhibitors are effective at killing cancer cells, but within a decade post-surgery around 30 per cent of patients will relapse and see their cancer return, usually because the cancer cells have adapted to the drug. Even worse, when cancer comes back it has usually spread around the body, which is difficult to treat,” added Dr Magnani.
Breast cancers are usually treated with surgery to remove the tumour, followed by a course of targeted hormone therapy, usually either aromatase inhibitors or the drug tamoxifen, which blocks oestrogen receptors.
Aromatase inhibitors are usually given to post-menopausal women, and prevent oestrogen from being produced in other tissues.
Although the women’s ovaries have stopped producing oestrogen, some of the hormones are still made in several other tissues by an enzyme called aromatase. The medication prevents this enzyme from making oestrogen.
However, around 30 per cent of breast cancer patients taking aromatase inhibitors see their cancer eventually return. This returning cancer is usually metastatic, meaning it has spread around the body, and the tumours are often now resistant to aromatase inhibitors.
“Our study shows how drug resistance and the invasiveness of cancer cells are interconnected in breast cancer through changes in cell shape. If we understand how to block resistance, we might also be able to prevent cancer spreading throughout the body – which would be an important step in treating breast cancer more effectively,” said Dr Fernando Calvo, the study’s team leader.