Identification of Extracellular and Intracellular Signaling Components of the Mammary Adipose Tissue and Its Interstitial Fluid in High Risk Breast Cancer Patients

doi:10.1074/mcp.M500030-MCP200

Identification of Extracellular and Intracellular Signaling Components of the Mammary Adipose Tissue and Its Interstitial Fluid in High Risk Breast Cancer Patients

Toward Dissecting The Molecular Circuitry of Epithelial-Adipocyte Stromal Cell Interactions*

From the ^‡Department of Proteomics in Cancer, Institute of Cancer Biology and ^§Danish Centre for Translational Breast Cancer Research, Danish Cancer Society and the ^‖Department of Breast and Endocrine Surgery and ^**Department of Pathology, The Centre of Diagnostic Investigations, Copenhagen University Hospital, DK-2100 Copenhagen, Denmark

¶To whom correspondence should be addressed. Tel.: 45-35-25-73-63; Fax: 45-35-25-77-55; E-mail: jec{at}cancer.dk

Abstract

It has become clear that growth and progression of breast tumor cells not only depend on their malignant potential but also on factors present in the tumor microenvironment. Of the cell types that constitute the mammary stroma, the adipocytes are perhaps the least well studied despite the fact that they represent one of the most prominent cell types surrounding the breast tumor cells. There is compelling evidence demonstrating a role for the mammary fat pad in mammary gland development, and some studies have revealed the ability of fat tissue to augment the growth and ability to metastasize of mammary carcinoma cells. Very little is known, however, about which factors adipocytes produce that may orchestrate these actions and how this may come about. In an effort to shed some light on these questions, we present here a detailed proteomic analysis, using two-dimensional gel-based technology, mass spectrometry, immunoblotting, and antibody arrays, of adipose cells and interstitial fluid of fresh fat tissue samples collected from sites topologically distant from the tumors of high risk breast cancer patients that underwent mastectomy and that were not treated prior to surgery. A total of 359 unique proteins were identified, including numerous signaling molecules, hormones, cytokines, and growth factors, involved in a variety of biological processes such as signal transduction and cell communication; energy metabolism; protein metabolism; cell growth and/or maintenance; immune response; transport; regulation of nucleobase, nucleoside, and nucleic acid metabolism; and apoptosis. Apart from providing a comprehensive overview of the mammary fat proteome and its interstitial fluid, the results offer some insight as to the role of adipocytes in the breast tumor microenvironment and provide a first glance of their molecular cellular circuitry. In addition, the results open new possibilities to the study of obesity, which has a strong association with type 2 diabetes, hypertension, and coronary heart disease.

Footnotes

Published, MCP Papers in Press, February 2, 2005, DOI 10.1074/mcp.M500030-MCP200
↵1 The criteria for high risk cancer applied by Danish Cooperative Breast Cancer Group are age below 35 years old, and/or tumor diameter of more than 20 mm, and/or histological malignancy grade 2 or 3, and/or negative estrogen and progesterone receptor status, and/or positive axillary status. Patients received no treatment prior to surgery.
↵2 The abbreviations used are: FIF, fat interstitial fluid; 2D, two-dimensional; A-FABP, adipocyte fatty acid-binding protein; TIF, tumor interstitial fluid; IL, interleukin; TGF, transforming growth factor; TNF, tumor necrosis factor; IGF, insulin-like growth factor; CSF, colony-stimulating factor; TIMP, tissue inhibitor of metalloproteinases; MAPK, mitogen-activated protein kinase; MDM2, mouse double minute 2; ER, estrogen receptor; ERK, extracellular signal-regulated kinase; CBP, cAMP-response element-binding protein (CREB)-binding protein; JNK, c-Jun NH₂-terminal kinase; MEK, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase.
↵3 P. Gromov, I. Gromova, and J. E. Celis, unpublished data.
↵* This work was supported by the Danish Cancer Society through the budget of the Institute of Cancer Biology and by grants from the Danish Medical Research Council, the Natural and Medical Sciences Committee of the Danish Cancer Society, The Novo Research Foundation, and the John and Birthe Meyer Foundation. Support was also received from the Marketing Department at the Danish Cancer Society.
- Received February 1, 2005.
- Revision received February 2, 2005.