Peptidomic analysis of breast cancer reveals a putative surrogate marker for estrogen receptor-negative carcinomas.

Estrogen-receptor status provides a major biomarker in breast cancer classification and has an important impact on prognosis and treatment options. The aim of this study was to investigate peptide profiles of invasive breast cancer with positive (n=39) and negative receptor status (n=41). Peptide profiles were generated by 'Differential Peptide Display', which is an offline-coupled combination of reversed-phase-HPLC and MALDI mass spectrometry. Mass spectrometric data were correlated with the immunohistochemically determined receptor state. Identification of peptides of interest was carried out by additional mass spectrometric methods (eg MALDI-TOF-TOF-MS-MS). Approximately 3000-7000 signals were detected per sample and thymosin alpha-1, an asparaginyl endopeptidase generated cleavage product of the ubiquitous acidic protein prothymosin-alpha, was found to differentiate the tumor samples according to their receptor status with the highest specificity. The concentration of Thymosin alpha-1 was found to be upregulated (n=37) in estrogen-negative cancer samples and downregulated (n=32) in estrogen-positive breast cancer samples. The expression of the precursor protein (Prothymosin-alpha) has been discussed previously as a prognostic factor in breast cancer. It is involved in the ER signal transduction pathway as an anti-coactivator-inhibitor. From our findings we conclude that Thymosin alpha-1 could serve as a surrogate marker in breast cancers and may indicate ER functionality.

Impaired CD14-dependent and independent response of polymorphonuclear leukocytes in preterm infants.

UNLABELLED: Preterm newborn infants are especially susceptible to Gram-negative sepsis that is associated with a lethality of up to 40%. AIMS: We tested whether polymorphonuclear leukocytes (PMN) from preterm infants exhibit an impaired antibacterial response upon stimulation with lipopolysaccharide (LPS) from Escherichia coli when compared to full term newborns or adults. METHODS: We studied the effect of LPS on the expression of the surface proteins CD11b and CD14 and the secretion of elastase by PMN from preterm infants, term infants and adults ex vivo. RESULTS: We found a significantly reduced antibacterial activity of PMN from preterm infants upon stimulation with LPS as indicated by low surface expression of the adhesion molecule CD11b and the reduced secretion of PMN elastase. LPS-induced CD11b expression was dependent on binding of LPS to the surface protein CD14 as CD14 antibodies inhibited LPS dependent CD11b upregulation. Furthermore CD14 expression was lower on PMN from preterm infants than from adults. In addition, CD14 independent upregulation of CD11b in response to tumor necrosis factor (TNF-alpha), N-formyl peptides (FMLP) and phorbol ester (PMA) was impaired. CONCLUSION: PMN from preterm infants are distinctly hyporesponsive to LPS, which may explain the predisposition of these children to invasive disease due to gramnegative bacteria.

Inhibition of hepatic transcriptional induction of lipopolysaccharide-binding protein by transforming-growth-factor beta 1.

LPS-binding protein (LBP) is an acute-phase protein with the ability to bind and transfer LPS of Gram-negative bacteria, as well as cell wall compounds of other pathogenic bacteria. This soluble pattern-recognition molecule is present in high concentrations in serum and represents an important defense mechanism of the host. Regulation of the hepatic acute-phase response and its termination are important mechanisms for limiting systemic inflammatory activity of the host organism. We show here that TGF-beta 1, in a dose-dependent fashion, is able to inhibit LBP transcript accumulation and LBP protein synthesis induced by IL-6, IL-1 beta and dexamethasone in hepatoma cell lines. These data were confirmed employing primary human hepatocytes, where TGF-beta 1 also inhibited LBP protein synthesis. We identified and analyzed several Smad-binding sites (Smads are major regulatory elements of TGF-beta 1) within the LBP promoter, and found that one of them was active. We furthermore identified an AP-1-binding site clearly conferring inhibitory effects of TGF-beta 1 towards LBP promoter activity, shown by gel shift and promoter mutagenesis experiments. Further elucidating the mechanism of transcriptional regulation of proteins involved in innate immune responses may potentially help to develop novel intervention strategies for the acute-phase response, sepsis, and septic shock.

Expression profiling of breast cancer cells by differential peptide display.

Expression profiling of RNAs or proteins has become a promising means to investigate the heterogeneity of histopathologically defined classes of cancer. Peptides, representing degradation as well as processing products of proteins offer an even closer insight into cell physiology. Peptides are related to the turnover of cellular proteins and are capable to reflect disease-related changes in homoeostasis of the human body. Furthermore, peptides derived from tumor cells are potentially useful markers in the early detection of cancer. In this study, we introduced a method called differential peptide display (DPD) for separating, detecting, and identifying native peptides derived from whole cell extracts. This method is a highly standardized procedure, combining the power of reversed-phase chromatography with mass spectrometry. This technology is suitable to analyze cell lines, various tissue types and human body fluids. Peptide-based profiling of normal human mammary epithelial cells (HMEC) and the breast cancer cell line MCF-7 revealed complex peptide patterns comprising of up to 2300 peptides. Most of these peptides were common to both cell lines whereas about 8% differed in their abundance. Several of the differentially expressed peptides were identified as fragments of known proteins such as intermediate filament proteins, thymosins or Cathepsin D. Comparing cell lines with native tumors, overlapping peptide patterns were found between HMEC and a phylloides tumor (CP) on the one hand and MCF-7 cells and tissue from a invasive ductal carcinoma (DC) on the other hand.