1. ¹Lung Cancer Biology Group, Division of Medicine, Imperial College Faculty of Medicine, Hammersmith Hospital, London, UK
2. ²CRUK London Research Institute, London, UK
3. ³Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, Switzerland

Correspondence: Dr A Arcaro, Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland. E-mail: Alexandre.Arcaro@kispi.unizh.ch

⁴Current address: MRC Centre for Developmental Neurobiology, New Hunt's House, Guy's Campus, London SE1 1UL, UK.

Received 20 April 2005; Revised 29 July 2005; Accepted 5 August 2005; Published online 19 September 2005.

Abstract

The impact of the 3-hydroxy-3methylglutaryl CoA reductase inhibitor simvastatin on human small-cell lung cancer (SCLC) cell growth and survival was investigated. Simvastatin profoundly impaired basal and growth factor-stimulated SCLC cell growth in vitro and induced apoptosis. SCLC cells treated with simvastatin were sensitized to the effects of the chemotherapeutic agent etoposide. Moreover, SCLC tumour growth in vivo was inhibited by simvastatin. These responses correlated with the inhibition of stem cell factor (SCF)-stimulated activation of extracellular signal-regulated kinase (Erk), protein kinase B (PKB) and ribosomal S6 kinase by simvastatin. Constitutive activation of the Erk pathway was sufficient to rescue SCLC cell from the effects of simvastatin. The drug did not directly affect activation of c-Kit or its localization to lipid rafts, but in addition to its ability to block Ras membrane localization, it selectively downregulated H-Ras protein levels at the post-translational level. Downregulation of either H- or K-Ras by RNA interference (RNAi) did not impair Erk activation by growth factors, whereas an RNAi specific for N-Ras inhibited activation of Erk, PKB and SCLC cell growth. Together our data demonstrate that inhibiting Ras signalling with simvastatin potently disrupts growth and survival in human SCLC cells.