1. ¹Department of Obstetrics and Gynaecology, Qilu Hospital of Shandong University, 107 Wenhuaxi Road, Jinan 250012, PR China
2. ²Gynaecological Cancer Research Centre, The Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria 3053, Australia
3. ³Department of Obstetrics and Gynaecology, The University of Melbourne, Victoria, Australia

Correspondence: Dr N Ahmed, Gynaecological Cancer Research Centre, The Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria 3053, Australia. E-mail: nuzhata@unimelb.edu.au

Received 20 June 2004; Revised 20 September 2004; Accepted 28 September 2004; Published online 7 December 2004.

Abstract

The peroxisome proliferator-activated receptors (PPARs) belong to a subclass of nuclear hormone receptor that executes important cellular transcriptional functions. Previous studies have demonstrated the expression of PPAR in several tumours including colon, breast, bladder, prostate, lung and stomach. This study demonstrates the relative expression of PPAR in normal ovaries and different pathological grades of ovarian tumours of serous, mucinous, endometrioid, clear cell and mixed subtypes. A total of 56 ovarian specimens including 10 normal, eight benign, 10 borderline, seven grade 1, nine grade 2 and 12 grade 3 were analysed using immunohistochemistry. Immunoreactive PPAR was not expressed in normal ovaries. Out of eight benign and 10 borderline tumours, only one tumour in each group showed weak cytoplasmic PPAR expression. In contrast, 26 out of 28 carcinomas studied were positive for PPAR expression with staining confined to cytoplasmic and nuclear regions. An altered staining pattern of PPAR was observed in high-grade ovarian tumours with PPAR being mostly localized in the nuclei with little cytoplasmic immunoreactivity. On the other hand, predominant cytoplasmic staining was observed in lower-grade tumours. Significantly increased PPAR immunoreactivity was observed in malignant ovarian tumours (grade 1, 2 and 3) compared to benign and borderline tumours (²=48.80, P<0.001). Western blot analyses showed significant elevation in the expression of immunoreactive PPAR in grade 3 ovarian tumours compared with that of normal ovaries and benign ovarian tumours (P<0.01). These findings suggest an involvement of PPAR in the onset and development of ovarian carcinoma and provide an insight into the regulation of this molecule in the progression of the disease.