Aggressive breast cancers dubbed 'triple negative' could one day be treated by inhibiting a protein that helps to control the initiation of mitosis — the segregation of copies of DNA strands that precedes cell division.

The growth of these tumours depends on the protein WEE1, which prevents cells from entering mitosis too early. Nicholas Turner at the Institute of Cancer Research in London and his team treated cultured breast cancer cells with an experimental drug that inhibits WEE1, and an approved therapy, gemcitabine, that prevents new DNA from being made. The combined treatment sent cells into mitosis before they had finished copying their DNA, eventually triggering programmed cell death.

The treatment also induced early mitosis in human colon cancer cells that had been implanted into mice, and caused the tumours to grow more slowly than did treatment with either drug alone.

Cancer Discov. http://dx.doi.org/10.1158/2159-8290.CD-11-0320 (2012)