Proteomic profiling of amniotic fluid in preterm labor using two-dimensional liquid separation and mass spectrometry.

OBJECTIVE: Simultaneous analysis of the protein composition of biological fluids is now possible. Such an approach can be used to identify biological markers of disease and to understand the pathophysiology of disorders that have eluded classification, diagnosis, and treatment. The purpose of this study was to analyze the differences in protein composition of the amniotic fluid of patients in preterm labor. STUDY DESIGN: Amniotic fluid was obtained by amniocentesis from three groups of women with preterm labor and intact membranes: (1) women without intra-amniotic infection/inflammation (IAI) who delivered at term, (2) women without IAI who delivered a preterm neonate, and (3) women with IAI. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an elevated amniotic fluid interleukin (IL)-6 (> or =2.3 ng/mL). Two-dimensional (2D) chromatography was used for analysis. The first dimension separated proteins by isoelectric point, while the second, by the degree of hydrophobicity. 2D protein maps were generated using different experimental conditions (reducing agents as well as protein concentration). The maps were used to discern subsets of isoelectric point/hydrophobicity containing differentially expressed proteins. Protein identification of differentially expressed fractions was conducted with mass spectrometry. Enzyme-linked immunosorbent assays (ELISA) as well as surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS)-based on-chip antibody capture immunoassays were also used for confirmation of a specific protein that was differentially expressed. RESULTS: (1) Amniotic fluid protein composition can be analyzed using a combination of 2D liquid chromatography and mass spectrometry for the identification of proteins differentially expressed in patients in preterm labor. (2) While total insulin-like growth factor-binding protein-1 (IGFBP-1) concentration did not change, IGFBP-1 fragments at about 13.5 kDa were present in patients with IAI. (3) Proteins that were over-expressed in group 1 included von Ebner gland protein precursor, IL-7 precursor, apolipoprotein A1, tropomyosin sk1 (TPMsk1) fragment, ribosomal protein S6 kinase alpha-3, and alpha-1-microglobulin/bikunin precursor (AMBP). (4) Proteins that were over-expressed in group 3 included fibrinopeptide B, transferrin, major histocompatibility complex (MHC) class 1 chain-related A antigen fragment, transcription elongation factor A, sex-determining region Y (SRY) box 5 protein, Down syndrome critical region 2 protein (DSCR2), and human peptide 8 (HP8). (5) One protein, retinol-binding protein, was over-expressed in women who delivered preterm, regardless of the presence of IAI. CONCLUSIONS: A combination of techniques involving 2D chromatography, mass spectrometry, and immunoassays allows identification of proteins that are differentially regulated in the amniotic fluid of patients with preterm labor. Specifically, the amount of the IGFBP-1 fragments at approximately 13.5 kDa was found to be increased in patients with IAI, while the amount of the intact form of IGFBP-1 was decreased.

Painting with a molecular brush: genomic/proteomic interfacing to define the drug action profile of novel solid-tumor selective anticancer agents.

XK469 is an investigational anticancer agent that exhibits antiproliferative activity in tumor-bearing animal models. We examined the drug-action profile of this agent at the molecular level regarding alterations induced in gene expression and proteins in HCT-116 human colon adenocarcinoma cells. We used a unique cDNA microarray (GeneMap(TM) Cancerarray) comprising 1152 human tumor-related genes and 2-D gel electrophoresis, respectively, following a 24-hour exposure to a drug concentration that killed a two-log fraction of HCT-116 clonogenic cells. Functional gene cluster profile (FGCP) analysis of the 71 out of 1152 genes that displayed a >2-fold increase or decrease in expression (over untreated control) identified a drug-specific involvement of the MAPK signal transduction pathway. MAPK signaling together with the involvement of ubiquitin proteins from 2-D gel electrophoresis suggest a novel drug-action profile at the molecular level for the in vitro antiproliferative activity of XK469.