Is there a human homologue to the murine proteolysis-inducing factor?

PURPOSE: A tumor-derived proteolysis-inducing factor (PIF) is suggested to be a potent catabolic factor in skeletal muscle of mice and humans. We aimed to establish the clinical significance of PIF in cancer patients and to elucidate its structural features. EXPERIMENTAL DESIGN: PIF was detected in human urine using a monoclonal antibody (mAb) and related to clinical outcomes. PIF immunoaffinity-purified using the mAb was purified/separated using reverse-phase high-performance liquid chromatography and two-dimensional electrophoresis. Ten human cancer cell lines were tested for expression of mRNA encoding PIF core peptide. RESULTS: PIF immunoreactivity was present in 160 of 262 patients with advanced cancers of the lung, esophagus/stomach, and other organs. In a Kaplan-Meier survival analysis of 181 lung cancer patients, PIF was unrelated to survival; PIF status was also unrelated to skeletal muscle loss confirmed by computed tomography imaging. PIF was seen in 16 of 24 patients with chronic heart failure and thus is not exclusive to malignant disease. In-gel digestion and mass spectrometric analysis of immunoaffinity purified PIF from cancer patients consistently identified human albumin and immunoglobulins. We showed nonspecific binding of purified albumin and immunoglobulins to the anti-PIF mAb, which is thus not a useful tool for PIF detection or purification in humans. Finally, the human PIF core peptide was detected in human cancer cell lines using reverse transcription-PCR and nucleotide sequencing; however, none of the amplified products had a site for the glycosylation critical to the proteolysis-inducing activity of murine PIF. CONCLUSIONS: A putative human homologue of murine PIF and its role in human cancer cachexia cannot be verified.

Derivation and Validation of a Serum Biomarker Panel to Identify Infants With Acute Intracranial Hemorrhage.

Importance: Abusive head trauma is the leading cause of death from physical abuse. Missing the diagnosis of abusive head trauma, particularly in its mild form, is common and contributes to increased morbidity and mortality. Serum biomarkers may have potential as quantitative point-of-care screening tools to alert physicians to the possibility of intracranial hemorrhage. Objective: To identify and validate a set of biomarkers that could be the basis of a multivariable model to identify intracranial hemorrhage in well-appearing infants using the Ziplex System. Design, Setting, and Participants: Binary logistic regression was used to develop a multivariable model incorporating 3 serum biomarkers (matrix metallopeptidase-9, neuron-specific enolase, and vascular cellular adhesion molecule-1) and 1 clinical variable (total hemoglobin). The model was then prospectively validated. Multiplex biomarker measurements were performed using Flow-Thru microarray technology on the Ziplex System, which has potential as a point-of-care system. The model was tested at 3 pediatric emergency departments in level I pediatric trauma centers (Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; Primary Children's Hospital, Salt Lake City, Utah; and Lurie Children's Hospital, Chicago, Illinois) among well-appearing infants who presented for care owing to symptoms that placed them at increased risk of abusive head trauma. The study took place from November 2006 to April 2014 at Children's Hospital of Pittsburgh, June 2010 to August 2013 at Primary Children's Hospital, and January 2011 to August 2013 at Lurie Children's Hospital. Main Outcomes and Measures: A mathematical model that can predict acute intracranial hemorrhage in infants at increased risk of abusive head trauma. Results: The multivariable model, Biomarkers for Infant Brain Injury Score, was applied prospectively to 599 patients. The mean (SD) age was 4.7 (3.1) months. Fifty-two percent were boys, 78% were white, and 8% were Hispanic. At a cutoff of 0.182, the model was 89.3% sensitive (95% CI, 87.7-90.4) and 48.0% specific (95% CI, 47.3-48.9) for acute intracranial hemorrhage. Positive and negative predictive values were 21.3% and 95.6%, respectively. The model was neither sensitive nor specific for atraumatic brain abnormalities, isolated skull fractures, or chronic intracranial hemorrhage. Conclusion and Relevance: The Biomarkers for Infant Brain Injury Score, a multivariable model using 3 serum biomarker concentrations and serum hemoglobin, can identify infants with acute intracranial hemorrhage. Accurate and timely identification of intracranial hemorrhage in infants without a history of trauma in whom trauma may not be part of the differential diagnosis has the potential to decrease morbidity and mortality from abusive head trauma.

Radiation resistance of human melanoma analysed by retroviral insertional mutagenesis reveals a possible role for dopachrome tautomerase.

While melanomas are resistant to the cytotoxic effects of radiotherapy, little is known about the molecular mechanisms underlying this intrinsic resistance. Here, we describe the utilization of retroviral insertional mutagenesis to facilitate the analysis of genetic changes that are associated with radioresistance in human melanoma. A radial growth phase human melanoma cell line, WM35, was infected with a replication-defective amphotropic murine retrovirus and subsequently selected for X-ray radiation-resistant variants. Several radiation-resistant clones were independently isolated and characterized. Interestingly, these clones also displayed resistance to ultraviolet radiation and to the chemotherapeutic drug cis-diamminedichloroplatinum(II) (CDDP). By Northern and Western analyses, we showed that the expression of DOPAchrome tautomerase (DCT), also known as tyrosinase-related protein 2 (TYRP2), an enzyme that functions in eumelanin synthesis, was significantly elevated in the radiation-resistant clones relative to the parental WM35 cells. Moreover, the levels of DCT in a variety of human melanoma cell lines correlated with their relative levels of radioresistance and the enforced expression of DCT conferred increased resistance to UV(B) treatment. An analysis of stress signaling induced by radiation as well other cytotoxic stressors showed that resistance associated with DCT overexpression applied specifically to treatments that activate the ERK/MAPK pathway. Indeed, DCT overexpression in a melanoma cell line resulted in increased ERK activity. Moreover, ectopic expression of dominant-active MEK in this melanoma cell line conferred UV(B) resistance suggesting that the ERK/MAPK pathway downstream of DCT may play a critical role in radiation and drug resistance. Overall, given that each gamma- and UV(B)-resistant cell line also exhibited resistance to CDDP and that CDDP-resistant clones showed increased resistance to UV(B) irradiation, these results suggest a common mechanism underlying radio- and chemoresistance, which is mediated by DCT expression.

A novel mass spectrometry-based assay for GSK-3beta activity.

BACKGROUND: As a component of the progression from genomic to proteomic analysis, there is a need for accurate assessment of protein post-translational modifications such as phosphorylation. Traditional kinase assays rely heavily on the incorporation of gamma-P32 radiolabeled isotopes, monoclonal anti-phospho-protein antibodies, or gel shift analysis of substrate proteins. In addition to the expensive and time consuming nature of these methods, the use of radio-ligands imposes restrictions based on the half-life of the radionucleotides and pose potential health risks to researchers. With the shortcomings of traditional assays in mind, the aim of this study was to develop a high throughput, non-radioactive kinase assay for screening Glycogen Synthase Kinase-3beta (GSK-3beta) activity. RESULTS: Synthetic peptide substrates designed with a GSK-3beta phosphorylation site were assayed with both recombinant enzyme and GSK-3beta immunoprecipitated from NIH 3T3 fibroblasts. A molecular weight shift equal to that of a single phosphate group (80 Da.) was detected by surface enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) in a GSK-3beta target peptide (2B-Sp). Not only was there a dose-dependent response in molecular weight shift to the amount of recombinant GSK-3beta used in this assay, this shift was also inhibited by lithium chloride (LiCl), in a dose-dependent manner. CONCLUSION: We present here a novel method to sensitively measure peptide phosphorylation by GSK-3beta that, due to the incorporation of substrate controls, is applicable to either purified enzyme or cell extracts. Future studies using this method have the potential to elucidate the activity of GSK-3beta in vivo, and to screen enzyme activity in relation to a variety of GSK-3beta related disorders.

Development of a rapid serological assay for the diagnosis of strongyloidiasis using a novel diffraction-based biosensor technology.

BACKGROUND: Strongyloidiasis is a persistent human parasitic infection caused by the intestinal nematode, Strongyloides stercoralis. The parasite has a world-wide distribution, particularly in tropical and subtropical regions with poor sanitary conditions. Since individuals with strongyloidiasis are typically asymptomatic, the infection can persist for decades without detection. Problems arise when individuals with unrecognized S. stercoralis infection are immunosuppressed, which can lead to hyper-infection syndrome and disseminated disease with an associated high mortality if untreated. Therefore a rapid, sensitive and easy to use method of diagnosing Strongyloides infection may improve the clinical management of this disease. METHODOLOGY/PRINCIPAL FINDINGS: An immunological assay for diagnosing strongyloidiasis was developed on a novel diffraction-based optical bionsensor technology. The test employs a 31-kDa recombinant antigen called NIE derived from Strongyloides stercoralis L3-stage larvae. Assay performance was tested using retrospectively collected sera from patients with parasitologically confirmed strongyloidiasis and control sera from healthy individuals or those with other parasitoses including schistosomiasis, trichinosis, echinococcosis or amebiasis who were seronegative using the NIE ELISA assay. If we consider the control group as the true negative group, the assay readily differentiated S. stercoralis-infected patients from controls detecting 96.3% of the positive cases, and with no cross reactivity observed in the control group These results were in excellent agreement (κ = 0.98) with results obtained by an NIE-based enzyme-linked immunosorbent assay (ELISA). A further 44 sera from patients with suspected S. stercoralis infection were analyzed and showed 91% agreement with the NIE ELISA. CONCLUSIONS/SIGNIFICANCE: In summary, this test provides high sensitivity detection of serum IgG against the NIE Strongyloides antigen. The assay is easy to perform and provides results in less than 30 minutes, making this platform amenable to rapid near-patient screening with minimal technical expertise.

Elevated elafin/trappin-2 in the female genital tract is associated with protection against HIV acquisition.

OBJECTIVES: Globally, heterosexual intercourse is the primary route of HIV-1 (HIV) transmission. It follows that mechanisms that protect against HIV infection are likely operative at the genital mucosa. In HIV-resistant Kenyan sex workers who are highly exposed to HIV infection yet remain uninfected, protection correlates with HIV-specific immune responses and genetic factors. However, these factors do not entirely explain this model of natural immunity to HIV. We hypothesized that protection may be mediated by innate immune proteins in the genital tract of HIV-resistant sex workers. DESIGN AND METHODS: The genital proteome of mucosal secretions from HIV-resistant women was examined using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Cervical lavage samples were collected from 315 HIV-resistant, HIV-uninfected and HIV-infected commercial sex workers. RESULTS: Univariate analysis identified a 6 kDa biomarker of HIV resistance in genital secretions from these women. This protein was identified by tandem mass spectrometry as elafin and was found to be overexpressed in HIV-resistant women compared with HIV-uninfected (P = 0.001) and infected (P = 0.002) women. The elevated levels of elafin/trappin-2 in HIV-resistant women were confirmed using ELISA. The prospective association of elevated cervicovaginal elafin/trappin-2 levels with protection from HIV acquisition was then confirmed in an independent cohort of high-risk female sex workers. CONCLUSION: Using a unique proteomics approach in a large scale, cross-sectional cohort study, we identified elafin/trappin-2 as a novel innate immune factor, which is highly associated with resistance. This association was confirmed within an independent, prospective cohort study. Genital tract elafin/trappin-2 levels constitute a natural correlate of HIV protection in humans.

Identification of protein biomarkers in Dupuytren's contracture using surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS).

BACKGROUND: To study the protein expression profiles associated with Dupuytren's contracture (DC) to identify potential disease protein biomarkers (PBM) using a proteomic technology--Surface Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS). METHODS: Normal and disease palmar fascia from DC patients were analyzed using Ciphergen's SELDI-TOF-MS Protein Biological System II (PBSII) ProteinChip reader. Analysis of the resulting SELDI-TOF spectra was carried out using the peak cluster analysis program (BioMarker Wizard, Ciphergen). Common peak clusters were then filtered using a bootstrap algorithm called SAM (Significant Analysis of Microarrays) for increased fidelity in our analysis. RESULTS: Several differentially expressed low molecular weight (<20 kDa) tissue proteins were identified. Spectra generated using both ZipTipC18 aided Au array and WCX2 array based SELDI-TOF-MS were reproducible, with an average peak cluster mass standard deviation for both methods of <1.74 x10(-4). Initial peak cluster analysis of the SELDI spectra identified both up-(14) and down-(3)regulated proteins associated with DC. Further analysis of the peak cluster data using the bootstrap algorithm SAM identified three disease-associated protein features (4600.8 Da, 10254.5 Da, and 11405.1 Da) that were elevated (5.45, 11.7, and 4.28 fold, respectively, with a 0% median false discovery rate). CONCLUSION: SELDI-TOF-MS identified three potential low molecular weight tissue protein markers (p4.6DC, p1ODC, p11.7DC) for DC. The ability of SELDI-TOF-MS to resolve low molecular weight proteins suggests that the method may provide a means of deciphering the biomarker-rich low molecular weight region of the human proteome. Application of such novel technology may help clinicians to focus on specific molecular abnormalities in diseases with no known molecular pathogenesis, and uncover therapeutic and/or diagnostic targets.

The splenic microenvironment is a source of proangiogenesis/inflammatory mediators accelerating the expansion of murine erythroleukemic cells.

The stromal compartments of hematopoietic organs (eg, spleen) are known to influence the viability and growth of diseased hematopoietic progenitors. Here we have used Friend murine leukemia virus (F-MuLV)-induced erythroleukemia to investigate factors of the splenic microenvironment that may make it fertile for the expansion and survival of malignant erythroblasts. We found that splenectomized, erythroleukemic mice exhibited extended survival compared with age-matched sham controls. In vitro, the proliferation of primary erythroleukemic cells cocultured with leukemic-derived splenic adherent cells or their conditioned media was found to be significantly higher than that observed in cocultures with healthy-derived adherent splenic cells. Cytokine protein arrays revealed that F-MuLV-infected splenocytes secreted elevated levels of interleukin-6 (IL-6), vascular endothelial growth factor-A (VEGF-A), macrophage chemoattractant protein-5 (MCP-5), soluble tumor necrosis factor receptor-1 (sTNFR1), IL-12p70, tumor necrosis factor-alpha (TNF-alpha), and IL-2 over normal splenocytes. Medium supplemented with both VEGF-A and MCP-5 could sustain proliferation of primary erythroleukemic cells in vitro, and significant proliferative suppression was observed upon addition of neutralizing antibodies to either of these factors. Furthermore, in vivo administration of a neutralizing antibody to VEGF-A extended survival times of erythroleukemic mice in comparison with controls. These findings suggest that VEGF-A and MCP-5 are potentially pivotal paracrine mediators occurring within the diseased splenic microenvironment capable of promoting disease acceleration and expansion of erythroleukemic blasts.

Presenilin-1, nicastrin, amyloid precursor protein, and gamma-secretase activity are co-localized in the lysosomal membrane.

Alzheimer's disease (AD) is caused by the cerebral deposition of beta-amyloid (Abeta), a 38-43-amino acid peptide derived by proteolytic cleavage of the amyloid precursor protein (APP). Initial studies indicated that final cleavage of APP by the gamma-secretase (a complex containing presenilin and nicastrin) to produce Abeta occurred in the endosomal/lysosomal system. However, other studies showing a predominant endoplasmic reticulum localization of the gamma-secretase proteins and a neutral pH optimum of in vitro gamma-secretase assays have challenged this conclusion. We have recently identified nicastrin as a major lysosomal membrane protein. In the present work, we use Western blotting and immunogold electron microscopy to demonstrate that significant amounts of mature nicastrin, presenilin-1, and APP are co-localized with lysosomal associated membrane protein-1 (cAMP-1) in the outer membranes of lysosomes. Furthermore, we demonstrate that these membranes contain an acidic gamma-secretase activity, which is immunoprecipitable with an antibody to nicastrin. These experiments establish APP, nicastrin, and presenilin-1 as resident lysosomal membrane proteins and indicate that gamma-secretase is a lysosomal protease. These data reassert the importance of the lysosomal/endosomal system in the generation of Abeta and suggest a role for lysosomes in the pathophysiology of AD.

Expression of the translational repressor NAT1 in experimental models of cardiac hypertrophy.

The development of hypertension-induced cardiac hypertrophy is a complex process involving a number of biochemical pathways. In particular, the translation initiation pathway has been postulated to play an important role in controlling cellular growth and proliferation in the cardiovascular system. Recently, a fundamental translational repressor, NAT1 (novel APOBEC target 1), has been identified. We have previously shown that NATI is developmentally-regulated in the heart of neonatal rats and its expression correlates with periods of rapid cardiac growth. The present investigation was designed to determine whether the expression of NAT1 is modified in the left ventricle of spontaneously hypertensive rats and 2-kidney-1-clip (2K1C) hypertensive rats. Northern blot analysis revealed an increase in NAT1 mRNA expression which correlates with the onset of cardiac hypertrophy. Unlike its pattern of mRNA expression, however, NAT1 protein level did not differ significantly from their respective controls throughout the time course. Interestingly, several protein species ranging in size from approximately 40-70 kDa were detected by Western blotting, in addition to the full length 97 kDa NAT1. Since the NAT1 transcript is a known substrate for the enzyme APOBEC-1 and possibly APOBEC-2, we speculate that these proteins may represent truncated fragments of NAT1 resulting from the formation of premature translation termination codons along the NAT1 transcript by APOBEC editing. Together, these results show that the ventricular expression of NAT1 is regulated at the transcriptional level during the early stages of genetic and 2K1C-induced hypertension and may be involved in the onset of left ventricular hypertrophy.