1. ¹Faculty of Medicine, Institute of Pathology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
2. ²Hartwell Center for Bioinformatics and Biotechnology, St Jude Children's Research Hospital, Memphis, TN, USA
3. ³Clinic of General and Transplantation Surgery, University Ulm, Ulm, Germany
4. ⁴Department of Radiotherapy, Martin-Luther-University Halle-Wittenberg, Halle, Germany
5. ⁵Probiodrug AG, Halle, Germany
6. ⁶Institute of Medical Biometry and Informatics, University Halle-Wittenberg, Halle, Germany
7. ⁷Molecular Pharmacology, St Jude Children's Research Hospital, Memphis, TN, USA
8. ⁸Department of Urology, Technical University Dresden, Dresden, Germany
9. ⁹Junior Research Group, Institute of Pathology, Martin-Luther-University Halle-Wittenberg, Halle, Germany

Correspondence: Dr H Taubert, Faculty of Medicine, Institute of Pathology, Martin-Luther-University Halle-Wittenberg, Magdeburger Strasse 14, D-06097 Halle/Saale, Germany. E-mail: helge.taubert@medizin.uni-halle.de

¹⁰These authors contributed equally to this work.

Received 11 April 2006; Revised 15 June 2006; Accepted 6 July 2006; Published online 4 September 2006.

Abstract

Self-renewal is considered as a common property of stem cells. Dysregulation of stem cell self-renewal is likely a requirement for the development of cancer. Hiwi, the human Piwi gene, encodes a protein responsible for stem cell self-renewal. In this study, we investigated the expression of Hiwi at the RNA level by real-time quantitative PCR in 65 primary soft-tissue sarcomas (STS) and ascertained its impact on prognosis for STS patients. In a multivariate Cox's proportional hazards regression model, we found that an increased expression of Hiwi mRNA is a significant negative prognostic factor for patients with STS (P=0.017; relative risk 4.6, 95% confidence interval (CI) 1.3–16.1) compared to medium expression of Hiwi transcript. However, a low expression of Hiwi transcript is correlated with a 2.4-fold (CI 0.7–8.0) increased risk, but this effect was not significant (P=0.17). Altogether, high-level expression of Hiwi mRNA identifies STS patients at high risk of tumour-related death. This is the first report showing a correlation between expression of a gene involved in stem cell self-renewal and prognosis of cancer patients.