Cancer cells proliferate by sending the cell cycle into overdrive, but early attempts to target the cell cycle with drugs were marred by problems with toxicity. Now two groups show that shutting down cell-cycle proteins called D-type cyclins seems to stop tumour growth without affecting normal tissue.
Piotr Sicinski and his colleagues at the Dana-Farber Cancer Institute in Boston, Massachusetts, engineered mice in which the production of cyclin D1 can be switched on and off. Loss of the protein had no apparent effect on healthy adult mice, but halted the growth of mammary tumours in mice that were also genetically predisposed to developing breast cancer.
Sicinski's team, and Iannis Aifantis at the New York University School of Medicine and his colleagues, showed independently that loss of cyclin D3 either triggered the death of tumour cells, or prevented their growth, in mouse models and human cell lines of an aggressive form of leukaemia. Inhibiting downstream proteins called cyclin-D associated kinases also killed tumour cells.