Proteotranscriptomic Profiling of 231-BR Breast Cancer Cells: Identification of Potential Biomarkers and Therapeutic Targets for Brain Metastasis

Abstract

Brain metastases are a devastating consequence of cancer and currently there are no specific biomarkers or therapeutic targets for risk prediction, diagnosis, and treatment. Here the proteome of the brain metastatic breast cancer cell line 231-BR has been compared with that of the parental cell line MDA-MB-231, which is also metastatic but has no organ selectivity. Using SILAC and nanoLC-MS/MS, 1957 proteins were identified in reciprocal labeling experiments and 1584 were quantified in the two cell lines. A total of 152 proteins were confidently determined to be up-or down-regulated by more than twofold in 231-BR. Of note, 112/152 proteins were decreased as compared with only 40/152 that were increased, suggesting that down-regulation of specific proteins is an important part of the mechanism underlying the ability of breast cancer cells to metastasize to the brain. When matched against transcriptomic data, 43% of individual protein changes were associated with corresponding changes in mRNA, indicating that the transcript level is a limited predictor of protein level. In addition, differential miRNA analyses showed that most miRNA changes in 231-BR were up-(36/45) as compared with down-regulations (9/45). Pathway analysis revealed that proteome changes were mostly related to cell signaling and cell cycle, metabolism and extracellular matrix remodeling. The major protein changes in 231-BR were confirmed by parallel reaction monitoring mass spectrometry and consisted in increases (by more than fivefold) in the matrix metalloproteinase-1, ephrin-B1, stomatin, myc target-1, and decreases (by more than 10-fold) in transglutaminase-2, the S100 calcium-binding protein A4, and L-plastin. The clinicopathological significance of these major proteomic changes to predict the occurrence of brain metastases, and their potential value as therapeutic targets, warrants further investigation. Brain metastases affect 10 -20% of cancer patients with disseminated disease (1). Even small lesions can cause neurological disability, and the median survival time of patients with brain metastases is short, with about 80% mortality within one year of diagnosis. The molecular basis of cancer metastases to the brain remains unknown and with advances in the control of systemic disease, the incidence of brain metastases is increasing (1, 2). In the case of breast cancer, brain relapse typically occurs years after primary tumor excision, suggesting that disseminated breast cancer cells must first acquire specialized functions to invade and grow in this organ (3). Retrospective studies of breast cancer patients with brain metastases found that a young age at diagnosis, primary tumors that are estrogen receptor negative or overexpressing the human epidermal growth factor receptor 2 (HER2) 1 and/or epidermal growth factor receptor, and the From the ‡School

Effects of ErbB2 Overexpression on the Proteome and ErbB Ligand-specific Phosphosignaling in Mammary Luminal Epithelial Cells

“…The identified protein changes confirm data from our previous proteomic and transcriptional profiling of this cell model (12, 15, 17, 33), and comparison of gene and protein expression datasets allowed the identification of proteins that are either transcriptionally or post-transcriptionally regulated in response to ErbB2 overexpression. The correlation between altered protein and mRNA levels was similar to a previous study investigating a cell model of brain metastatic breast cancer, suggesting that there may generally be a correlation factor close to 0.6 between protein and mRNA in breast epithelial cells (34). Notably, some of the same proteins were altered, possibly implicating their involvement in the molecular mechanisms by which ErbB2-overexpressing breast tumors metastasize to the brain.…”

The influence of matrix stiffness on the behavior of brain metastatic breast cancer cells in a biomimetic hyaluronic acid hydrogel platform

“…S3 and S4). However, as the available breast cancer cell lines, including metastatic breast cancer cells, differ in their biological and genetic makeup, a detailed investigation of the cell‐type specific behavior would be needed while adapting this platform to study the underlying mechanobiology . In addition to adhesion, spreading, and proliferation, we showed that the MDA‐MB‐231Br single cell migration is regulated by matrix stiffness (Fig.…”

Finding Needles in Haystacks: The Use of Quantitative Proteomics for the Early Detection of Colorectal Cancer

“…Finding Needles in Haystacks: The Use of Quantitative Proteomics for the Early Detection… DOI: http://dx.doi.org /10.5772/intechopen.80942 Acronyms and abbreviations cancer/carbohydrate antigen 19…”

“…Over the last 2 decades, unprecedented technological advancement in proteinbased mass spectrometry (proteomics) has radically changed the landscape of biomarker research [13] (Table 1). This has facilitated the characterization of complex cellular proteomes [14][15][16][17][18][19], research that has identified hundreds of over and under expressed proteins in carcinoma patients using tumor tissue, histological sections, plasma or fecal samples when compared to matched normal tissues [20][21][22][23][24]. Despite this, with the exception of Carcinoembryonic antigen (CEA) and Cancer antigen [25], no new protein biomarkers have made it into routine clinical practice [21,26,27].…”