Scientists Crack the Code to Tamoxifen Resistance

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Article Summary
Scientists Crack the Code to Tamoxifen Resistance

PharmaLive News Archive - 12-Nov-2008
Tamoxifen is given to most women for five years after they are first diagnosed with breast cancer to help prevent the disease from coming back but some women develop resistance to the treatment after time, meaning their cancer is more likely to return. The production of oestrogen can cause breast cancer cells to grow and divide but tamoxifen prevents oestrogen from causing breast cancer cells to grow, helping to lower the risk of the disease returning.


Summary
• LONDON, Nov. 13, 2008--Cancer Research UK scientists have discovered the molecular basis for tamoxifen response in breast cancer cells - and the reason why some women can develop resistance to the treatment, according to a study published in Nature* today (Wednesday).
• Tamoxifen is given to most women for five years after they are first diagnosed with breast cancer to help prevent the disease from coming back but some women develop resistance to the treatment after time, meaning their cancer is more likely to return.
• Researchers at the Cancer Research UK Cambridge Research Institute have discovered for the first time the mechanism by which the breast cancer therapy tamoxifen operates.
• It switches off a breast cancer gene ErbB2 via a protein called Pax2.
• Pax2 acts as a ‘switch’ to keep ErbB2 switched off.
• Tamoxifen resistance occurs when ErbB2 remains switched on.
• Previously it was known that tamoxifen worked by blocking oestrogen from causing unchecked cell growth in breast cancer by switching certain genes on but the mechanism by which this occurred was unknown.
• Lead author, Dr Jason Carroll, said: “We knew that women developed resistance to tamoxifen but previously our understanding of why this occurred could be compared with trying to fix a broken car without knowing how the engine worked.