The results suggest that proton transfer from a matrix molecule to an analyte plays an important role in the ionization step. The transferring proton may be derived from pbotoionized or electronically excited matrix molecules. In contrast, some data are most consistent with a gas-phase mechanism for [ M + Nal' ions.

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors in Southeast Asia. Unfortunately, most NPC victims have had metastasis when first diagnosed due to its deep location and vague symptoms. To date, discovery of sensitive and specific biomarkers for improving detection of NPC remains a challenge. Our previous study established a strategy for cell secretome analysis using a hollow fiber culture (HFC) system combined with liquid chromatography mass spectrometry. Herein, the above platform was used to collect NPC secretome for the discovery of relevant clinical biomarkers. Among 66 identified proteins, chloride intracellular channel 1 (CLIC1) was sieved out for intended use as a potential NPC biomarker candidate. Approximately 75% of NPC tissue specimens showed positive CLIC1 staining by IHC. The plasma levels of CLIC1 in NPC patients (N = 70), as presented by sandwich ELISA, were significantly higher than those in the healthy controls (N = 74) (mean +/- SD, 16.38 +/- 26.53 vs 2.39 +/- 5.32 microg/mL; p = 0.00005). Using a cutoff point of 2.58 microg/mL, CLIC1 successfully discriminated NPC from the benign healthy control group with a sensitivity of 63% and a specificity of 77%. The area under the receiver operating characteristic curve was determined to be 0.74 (95% CI, 0.652-0.818). The statistical analysis of CLIC1 level in plasma shows that CLIC1 could be applied as a marker for early detection of NPC. This is the first report for the detection of CLIC1 as a plasma marker. Our results indicate that the analytical platform could provide a feasible strategy to profile tumor cell secretome for identifying cancer biomarkers, and CLIC1 may be a novel plasma tumor marker for NPC.

Metastasis is a major obstacle that must be overcome for the successful treatment of lung cancer. Proteins secreted by cancer cells may facilitate the progression of metastasis, particularly within the phases of migration and invasion. To discover metastasis-promoting secretory proteins within cancer cells, we used the label-free quantitative proteomics approach and compared the secretomes from the lung adenocarcinoma cell lines CL1-0 and CL1-5, which exhibit low and high metastatic properties, respectively. By employing quantitative analyses, we identified 660 proteins, 68 of which were considered to be expressed at different levels between the two cell lines. Lung cancer is the leading cause of cancer death, and ϳ90% of all lung cancer deaths are attributed to metastases (1). Approximately 95% of lung cancer patients are not diagnosed until they develop symptoms, and 85% of the newly diagnosed lung cancer patients are already in the advanced stages of the disease (2, 3). Once the tumor cells have metastasized and spread throughout the lungs, the cancer is considerably more difficult to treat. Invasiveness and metastasis are major threats to successful treatment. Cancer metastasis is an intricate, multi-step process in which the tumor cells must gain both migratory and invasive properties (4). In metastasis research, there are two common in vivo models, spontaneous and experimental metastasis (5-7). In brief, spontaneous metastasis refers to primary tumor cells that are able to dissociate from the primary tumor and metastasize to the secondary organ via the circulatory system. In contrast, experimental metastasis refers to the injection of tumor cells directly into the systemic circulation. Many researchers have attempted to determine the molecular basis of these transitions in hopes of developing target-specific drugs or biomarkers for the prevention and diagnosis of metastasis. Although there have been many discoveries regarding a particular proFrom the ‡Department

Four consecutive doses (10 mg/kg) of methamphetamine, s.c., produced a substantial striatal dopamine depletion in both sexes of BALB/c and C57BL/6J mice. Male C57BL/6J mice exhibited greater dopamine depletions in the striatum compared to female C57BL/6J mice. In contrast, male and female BALB/c mice demonstrated an equivalent magnitude of striatal dopamine depletion. Regardless of sex, C57BL/6J mice demonstrated approximately 1.4 to 2.2 times greater dopamine depletions in the striatum compared to BALB/c mice. Moreover, methamphetamine caused 4 times greater serotonin depletions in male as opposed to female BALB/c mice while sparing either sex of the C57BL/6J mice. Furthermore, female mice of both strains appeared to have the greatest basal dopamine levels during proestrus and the lowest basal dopamine levels during diestrus. Likewise, female mice of both strains exhibited the lowest dopamine depletions in the striatum when the dosing regimen of methamphetamine started at proestrus whereas the greatest dopamine depletions in the striatum occurred when the regimen started during diestrus. These results suggest that sex hormones and other modulating factors may play a role in methamphetamine-induced dopamine and serotonin neurotoxicity.

SummaryBoth viral effect and immune-mediated mechanism are involved in the pathogenesis of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection. In this study, we showed that in SARS patient sera there were autoantibodies (autoAbs) that reacted with A549 cells, the type-2 pneumocytes, and that these autoAbs were mainly IgG. The autoAbs were detectable 20 days after fever onset. Tests of non-SARS-pneumonia patients did not show the same autoAb production as in SARS patients.

Rab small GTPases are master regulators of membrane trafficking and guide vesicle targeting. Recent publications show that Rab-controlled trafficking pathways are altered during tumorigenesis. However, whether any of the Rabs plays a metastasis suppressor role is least explored. Here we address the metastasis suppressive function of human Rab37 (hRAB37) using secretomics, cell, animal and clinical analyses. We show that tissue inhibitor of metalloproteinase 1 (TIMP1), a secreted glycoprotein that inhibits extracellular matrix turnover, is a novel cargo of hRAB37. hRAB37 regulates the exocytosis of TIMP1 in a nucleotide-dependent manner to inactivate matrix metalloproteinase 9 (MMP9) migration axis in vitro and in vivo. Dysfunction of hRAB37 or TIMP1 abrogates metastasis suppression. Lung cancer patients with metastasis and poor survival show low hRAB37 protein expression coinciding with low TIMP1 in tumours. Our findings identify hRAB37 as a novel metastasis suppressor Rab that functions through the TIMP1-MMP9 pathway and has significant prognostic power.

Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer, which is one of the most prominent causes of cancer-related mortality worldwide. Discovery of serum tumor markers could facilitate early NSCLC detection and metastatic prognosis. Here, we simultaneously analyzed the NSCLC cell secretome and proteomic profiles of pleural effusion from lung adenocarcinoma patients for NSCLC biomarker discovery. Retinoblastoma-associated binding protein 46 (RbAp46), one of the proteins detected both in NSCLC cell secretome and pleural effusion proteome, was chosen for further evaluation. Both of RbAp46 mRNA and protein levels were upregulated significantly in NSCLC cancer tissues. Serum levels of RbAp46 were markedly higher in NSCLC patients than in healthy controls, and a combination of RbAp46 and CEA could outperform CEA alone in discriminating NSCLC patients from healthy persons. Importantly, elevated serum RbAp46 level was highly correlated with NSCLC distant metastasis. Moreover, knockdown of RbAp46 inhibited the migration ability of lung cancer cells. Our data collectively suggest that RbAp46 serves as a novel biomarker and prognosticator for NSCLC, and is involved in lung cancer cell migration.

Secreted proteins, referred to as the secretome, are known to regulate a variety of biological functions and are involved in a multitude of pathological processes. However, some secreted proteins from cell cultures are difficult to detect because of their intrinsic low abundance. They are frequently masked by proteins shed from lysed cells and the substantial amounts of serum proteins used in culture medium. We have proposed an analytical platform for sensitive detection of secreted proteins by utilizing a hollow fiber culture (HFC) system coupled with proteomic approaches. The HFC system enables culture of high-density cells in a small volume where secreted proteins can be accumulated. In addition, cell lysis rates can be greatly reduced, which alleviates the contamination from lysed cells. In this study, nasopharyngeal carcinoma (NPC) cells were utilized to evaluate the efficiency of this system in the collection and analysis of the cell secretome. Cells were adapted to serum-free medium and inoculated into the HFC system. The cell lysis rate in the culture system was estimated to be 0.001-0.022%, as determined by probing four intracellular proteins in the conditioned medium (CM), while a cell lysis rate of 0.32-1.84% was observed in dish cultures. Proteins in the CM were analyzed using SDS-PAGE and liquid chromatography tandem mass spectrometry (LC-MS/MS). A total of 134 proteins were identified in 62 gel bands, of which 61% possess a signal peptide and/or a transmembrane domain. In addition, 37% of the identified secretome were classified as extracellular or membrane proteins, whereas 98% of the lysate proteins were identified as intracellular proteins. We suggest that the HFC system may be used to collect secreted proteins efficiently and facilitate comprehensive characterization of cell secretome.