1. ¹UCD School of Biomolecular and Biomedical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield Dublin 4, Ireland
2. ²Max Delbrück Center (MDC) for Molecular Medicine, Robert-Rössle-Strae 10, Berlin D-13092, Germany
3. ³UCD School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield Dublin 4, Ireland
4. ⁴UCD School of Chemistry and Chemical Biology, Centre for Synthesis and Chemical Biology (CSCB), Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield Dublin 4, Ireland

Correspondence: Dr MM Mc Gee, E-mail: margaret.mcgee@ucd.ie

Revised 6 September 2007; Accepted 10 September 2007; Published online 9 October 2007.

Abstract

Titanocene compounds are a novel series of agents that exhibit cytotoxic effects in a variety of human cancer cells in vitro and in vivo. In this study, the antiproliferative activity of two titanocenes (Titanocenes X and Y) was evaluated in human epidermoid cancer cells in vitro. Titanocenes X and Y induce apoptotic cell death in epidermoid cancer cells, with IC50 values that are comparable to cisplatin. Characterisation of the cell death pathway induced by titanocene compounds in A431 cells revealed that apoptosis is preceded by cell cycle arrest and the inhibition of cell proliferation. The induction of apoptosis is dependent on the activation of caspase-3 and -7 but not caspase-8. Furthermore, the antitumour activity of Titanocene Y was tested in an A431 xenograft model of epidermoid cancer. Results indicate that Titanocene Y significantly reduced the growth of A431 xenografts with an antitumour effect similar to cisplatin. These results suggest that titanocenes represent a novel series of promising antitumour agents.