1. ¹Department of General, Visceral and Transplantation Surgery, The University of Ulm, Steinhövelstrasse 9, Ulm 89075, Germany
2. ²Institute of Pathology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 14, Halle 06097, Germany
3. ³Institute of Pathology, The University of Ulm, Albert-Einstein-Allee 11, Ulm 89081, Germany

Correspondence: Dr LF Grochola, Ludwig Institute for Cancer Research, University of Oxford; Old Road Campus, Off Roosevelt Drive; Oxford OX3 7DQ, UK. E-mail: lukasz.grochola@ludwig.ox.ac.uk

Received 8 July 2008; Revised 14 August 2008; Accepted 14 August 2008; Published online 9 September 2008.

Abstract

Piwi proteins and their interaction with piRNAs have rapidly emerged as important contributors to gene regulation, indicating their crucial function in germline and stem cell development. However, data on the Hiwi 1 (Hiwi) gene, one of the four human Piwi homologues, are still scarce. Therefore, we investigated the Hiwi mRNA expression in microdissected PDAC tissues from patients with ductal adenocarcinoma of the pancreas (PDAC) by quantitative real-time PCR and the protein expression by immunohistochemistry. Elevated levels of Hiwi mRNA transcripts were measured in 40 out of 56 tissues and a positive immunostaining of Hiwi was detected in tumours of 21 out of 78 patients. There was no general impact of elevated Hiwi mRNA transcript levels or protein expression on survival, as tested by multivariate Cox regression and Kaplan–Meier analysis. However, men showed a significantly increased risk for tumour-related death in case of down- or upregulated expression of Hiwi mRNA (relative risk (RR)=2.78; P=0.034). In summary, we report the first analysis of Hiwi expression in PDAC and its impact on prognosis. We suggest that alterations in mRNA expression of Hiwi can increase the risk of tumour-related death in male PDAC patients.