Purpose: Although numerous proteome studies have been performed recently to identify cancer-related changes in protein expression, only a limited display of relatively abundant proteins has been identified. The aim of this study is to identify novel proteins as potential tumor markers in primary colorectal cancer tissues using a high-resolution two-dimensional gel electrophoresis (2-DE).Experimental Design: 2-DE using an agarose gel for isoelectric focusing was used to compare protein profiling of 10 colorectal cancer tissues and adjacent normal mucosa. Altered expression and post-translational modification of several proteins were examined using Western blot analysis and immunohistochemistry.Results: Ninety-seven proteins of 107 spots (90.7%) that were differentially expressed between matched normal and tumor tissues were identified by mass spectrometry. Among them, 42 unique proteins (49 spots) significantly increased or decreased in the tumors. They include eukaryotic translation initiation factor 4H, inorganic pyrophosphatase, anterior gradient 2 homologue, aldolase A, and chloride intracellular channel 1, whose elevated expression in tumor tissues was confirmed by Western blot analysis and immunohistochemistry. Interestingly, only isoform 1 of two transcript variants of eukaryotic translation initiation factor 4H was greatly up-regulated in most of the tumor tissues.Moreover, post-translational modifications of the prolyl-4-hydroxylase ␤ subunit and annexin A2 also were identified.Conclusions: We identified several novel proteins with altered expression in primary colorectal cancer using agarose 2-DE. This method is a powerful technique with which to search for not only quantitative but also qualitative changes in a biological process of interest and may contribute to the deeper understanding of underlying mechanisms of human cancer.

No abstract

Sticholysin II (StnII) is a pore-forming toxin from the sea anemone Stichodactyla heliantus which belongs to the large actinoporin family. The toxin binds to sphingomyelin (SM) containing membranes, and shows high binding specificity for this lipid. In this study, we have examined the role of the hydrogen bonding groups of the SM long-chain base (i.e., the 2NH and the 3OH) for StnII recognition. We prepared methylated SM-analogs which had reduced hydrogen bonding capability from 2NH and 3OH. Both surface plasmon resonance experiments, and isothermal titration calorimetry measurements indicated that StnII failed to bind to bilayers containing methylated SM-analogs, whereas clear binding was seen to SM-containing bilayers. StnII also failed to induce calcein release (i.e., pore formation) from vesicles made to contain methylated SM-analogs, but readily induced calcein release from SM-containing vesicles. Molecular modeling of SM docked to the phosphocholine binding site of StnII indicated that the 2NH and 3OH groups were likely to form a hydrogen bond with Tyr135. In addition, it appeared that Tyr111 and Tyr136 could donate hydrogen bonds to phosphate oxygen, thus stabilizing SM binding to the toxin. We conclude that the interfacial hydrogen bonding properties of SM, in addition to the phosphocholine head group, are crucial for high-affinity SM/StnII-interaction.

Sphingomyelins (SMs) and sterols are important constituents of the plasma membrane and have also been identified as major lipid components in membrane rafts. Using SM analogs with decreasing headgroup methylation, we systemically analyzed the effect of headgroup size on membrane properties and interactions with cholesterol. An increase in headgroup size resulted in a decrease in the main phase transition. Atom-scale molecular-dynamics simulations were in agreement with the fluorescence anisotropy experiments, showing that molecular areas increased and acyl chain order decreased with increasing headgroup size. Furthermore, the transition temperatures were constantly higher for SM headgroup analogs compared to corresponding phosphatidylcholine headgroup analogs. The sterol affinity for phospholipid bilayers was assessed using a sterol-partitioning assay and an increased headgroup size increased sterol affinity for the bilayer, with a higher sterol affinity for SM analogs as compared to phosphatidylcholine analogs. Moreover, the size of the headgroup affected the formation and composition of cholesterol-containing ordered domains. Palmitoyl-SM (the largest headgroup) seemed to attract more cholesterol into ordered domains than the other SM analogs with smaller headgroups. The ordering and condensing effect of cholesterol on membrane lipids was also largest for palmitoyl-SM as compared to the smaller SM analogs. The results show that the size of the SM headgroup is crucially important for SM-SM and SM-sterol interactions. Our results further emphasize that interfacial electrostatic interactions are important for stabilizing cholesterol interactions with SMs.

BackgroundIt is important to screen for alcohol consumption and drinking customs in a standardized manner. The aim of this study was 1) to investigate whether the AUDIT score is useful for predicting hazardous drinking using optimal cutoff scores and 2) to use multivariate analysis to evaluate whether the AUDIT score was more useful than pre-existing laboratory tests for predicting hazardous drinking.MethodsA cross-sectional study using the Alcohol Use Disorders Identification Test (AUDIT) was conducted in 334 outpatients who consulted our internal medicine department. The patients completed self-reported questionnaires and underwent a diagnostic interview, physical examination, and laboratory testing.ResultsForty (23 %) male patients reported daily alcohol consumption ≥ 40 g, and 16 (10 %) female patients reported consumption ≥ 20 g. The optimal cutoff values of hazardous drinking were calculated using a 10-fold cross validation, resulting in an optimal AUDIT score cutoff of 8.2, with a sensitivity of 95.5 %, specificity of 87.0 %, false positive rate of 13.0 %, false negative rate of 4.5 %, and area under the receiver operating characteristic curve of 0.97. Multivariate analysis revealed that the most popular short version of the AUDIT consisting solely of its three consumption items (AUDIT-C) and patient sex were significantly associated with hazardous drinking. The aspartate transaminase (AST)/alanine transaminase (ALT) ratio and mean corpuscular volume (MCV) were weakly significant.ConclusionsThis study showed that the AUDIT score and particularly the AUDIT-C score were more useful than the AST/ALT ratio and MCV for predicting hazardous drinking.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3053-6) contains supplementary material, which is available to authorized users.