The functional roles of Cyclin D1, a component of the core cell cycle machinery, has been revealed recently by MB researcher, Dr. Siwanon Jirawatnotai, to have an unexpected function in DNA repair. He and his team used a proteomic screening for cyclin D1 protein partners in several types of human tumours. He found that cyclin D1 directly binds RAD51, and that cyclin D1–RAD51 interaction is induced by radiation. Like RAD51, cyclin D1 is recruited to DNA damage sites in a BRCA2-dependent fashion. Reduction of cyclin D1 levels in human cancer cells impaired recruitment of RAD51 to damaged DNA, impeded the homologous recombination-mediated DNA repair, and increased sensitivity of cells to radiation in vitro and in vivo. This effect was seen in cancer cells lacking the retinoblastoma protein, which do not require D-cyclins for proliferation. These findings reveal an unexpected function of a core cell cycle protein in DNA repair and suggest that targeting cyclin D1 may be beneficial also in retinoblastoma-negative cancers which are currently thought to be unaffected by cyclin D1 inhibition.

The work is published in the June 9, 2011 issue of Nature (Vol. 474 No. 7350 pp. 230-4).

Links to full paper at www.nature.com/nature/journal/v474/n7350/full/nature10155.html