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Open Access Research

Secretoglobin expression in ovarian carcinoma: lipophilin B gene upregulation as an independent marker of better prognosis

Eliana Bignotti1*, Renata A Tassi1, Stefano Calza23, Antonella Ravaggi1, Elisa Rossi4, Carla Donzelli5, Paola Todeschini1, Chiara Romani1, Elisabetta Bandiera1, Laura Zanotti1, Mario Carnazza1, Francesco Quadraro1, Germana Tognon1, Enrico Sartori1, Sergio Pecorelli1, Dana M Roque6 and Alessandro D Santin6

Author Affiliations

1 Angelo Nocivelli Institute of Molecular Medicine, Division of Gynecologic Oncology, University of Brescia, Viale Europa 11, 25123 Brescia, Italy

2 Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy

3 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden

4 Centro de Investigaciones Biologicas, Consejo Superior de Investigaciones Cientificas (CSIC) and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain

5 Department of Pathology, University of Brescia, Brescia, Italy

6 Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, New Haven, CT 06520-8063, USA

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Journal of Translational Medicine 2013, 11:162  doi:10.1186/1479-5876-11-162

Published: 2 July 2013

Abstract

Background

The aim of the present study was to investigate within ovarian carcinoma and normal ovarian biopsies the gene expression of multiple secretoglobin family members relative to mammaglobin B, which we previously reported as a promising novel ovarian carcinoma prognostic marker.

Methods

Using quantitative real-time Reverse Transcription PCR we tested 53 ovarian carcinoma and 30 normal ovaries for the expression of 8 genes belonging to the secretoglobin family: mammaglobin A, lipophilin A, lipophilin B, uteroglobin, HIN-1, UGRP-1, RYD5 and IIS. Next, we decided to expand the LipB gene expression analysis to a further 48 ovarian carcinoma samples, for a total of 101 tumor tissues of various histologies and to study its protein expression by immunohistochemistry in formalin-fixed paraffin-embedded tumors and normal ovaries. Finally, we correlated lipophilin B gene and protein expression to conventional patient clinico-pathological features and outcome.

Results

We found significant mammaglobin A, lipophilin A, lipophilin B and RYD5 gene overexpression in ovarian carcinomas compared to normal ovaries. Lipophilin B mRNA showed a higher presence in tumors (75.4%) compared to normal ovaries (16.6%) and the most significant correlation with mammaglobin B mRNA (rs =0.77, p < 0.001). By immunohistochemical analysis, we showed higher lipophilin B expression in the cytoplasm of tumor cells compared to normal ovaries (p < 0.001). Moreover, lipophilin B gene overexpression was significantly associated with serous histology (serous vs clear cell p = 0.027; serous vs undifferentiated p = 0.007) and lower tumor grade (p = 0.02). Lower LipB mRNA levels (low versus high tertiles) were associated to a shorter progression-free (p = 0.03, HR = 2.2) and disease-free survival (p = 0.02, HR = 2.5) by univariate survival analysis and, importantly, they remain an independent prognostic marker for decreased disease-free (p = 0.001, HR = 3.9) and progression-free survival (p = 0.004, HR = 2.8) in multivariate Cox regression analysis.

Conclusions

The present study represents the first quantitative evaluation of secretoglobin gene expression in normal and neoplastic ovarian tissues. Our results demonstrate lipophilin B gene and protein upregulation in ovarian carcinoma compared to normal ovary. Moreover, lipophilin B gene overexpression correlates with a less aggressive tumor phenotype and represents a novel ovarian carcinoma prognostic factor.

Keywords:
Ovarian carcinoma; Secretoglobins; Lipophilin B; Gene expression; Prognosis; Biomarker