Proteome–Metabolome Profiling of Ovarian Cancer Ascites Reveals Novel Components Involved in Intercellular Communication

Victoria O Shender,Marat S Pavlyukov,Rustam H Ziganshin,Georgij P Arapidi,Sergey I Kovalchuk,Nikolay A Anikanov,Ilya A Altukhov,Dmitry G Alexeev,Ivan O Butenko,Alexey L Shavarda,Elena B Khomyakova,Evgeniy Evtushenko,Lev A Ashrafyan,Irina B Antonova,Igor N Kuznetcov,Alexey Yu Gorbachev,Mikhail I Shakhparonov,Vadim M Govorun

doi:10.1074/mcp.m114.041194

Abstract

Ovarian cancer ascites is a native medium for cancer cells that allows investigation of their secretome in a natural environment. This medium is of interest as a promising source of potential biomarkers, and also as a medium for cell-cell communication. The aim of this study was to elucidate specific features of the malignant ascites metabolome and proteome. In order to omit components of the systemic response to ascites formation, we compared malignant ascites with cirrhosis ascites. Metabolome analysis revealed 41 components that differed significantly between malignant and cirrhosis ascites. Most of the identified cancer-specific metabolites are known to be important signaling molecules. Proteomic analysis identified 2096 and 1855 proteins in the ovarian cancer and cirrhosis ascites, respectively; 424 proteins were specific for the malignant ascites. Functional analysis of the proteome demonstrated that the major differences between cirrhosis and malignant ascites were observed for the cluster of spliceosomal proteins. Additionally, we demonstrate that several splicing RNAs were exclusively detected in malignant ascites, where they probably existed within protein complexes. This result was confirmed in vitro using an ovarian cancer cell line. Identification of spliceosomal proteins and RNAs in an extracellular medium is of particular interest; the finding suggests that they might play a role in the communication between cancer cells. In addition, malignant ascites contains a high number of exosomes that are known to play an important role in signal transduction. Thus our study reveals the specific features of malignant ascites that are associated with its function as a medium of intercellular communication.

Highlights

Ovarian cancer is the sixth most frequently occurring cancer among the gynecological cancers and accounts for about 5% of all new female cancer cases according to the 2012 data (World Health Organization International Agency for Research on Cancer www.globocan.iarc.fr)
Samples—Ten ovarian cancer ascites and five portal alcoholic cirrhosis ascites samples were used in this study
Metabolic Profiles of Ascitic Fluids—Our GC-MS-based metabolomic analysis of ascites derived from patients with ovarian cancer and portal alcoholic cirrhosis resulted in the detection of 129 compounds, and 89 of these compounds were identified as known metabolites

Summary

Introduction

Ovarian cancer is the sixth most frequently occurring cancer among the gynecological cancers and accounts for about 5% of all new female cancer cases according to the 2012 data (World Health Organization International Agency for Research on Cancer www.globocan.iarc.fr). The rate of mortality from ovarian cancer holds first place among the other gynecological cancers, largely because of the asymptomatic progression of the disease, especially at its early stages, and a lack of adequate screening tests, which leads to late detection, typically only after the cancer has spread to adjacent structures. In such a case, the five-year survival rate is only 25% to 40%, whereas it can be as high as 90% if the cancer is diagnosed early. We extended our knowledge of the protein composition and filled in gaps regarding the metabolome, and elucidated specific features of malignant ascites composition

Objectives

Results

Conclusion