Structural Decoding of the Netrin-1/UNC5 Interaction and its Therapeutical Implications in Cancers.

Netrin-1 has been shown to be up-regulated in a fraction of human cancers as a mechanism to allow these tumors to escape the pro-apoptotic activity of some of its main dependence receptors, the UNC5 homologs (UNC5H). Here we identify the V-2 domain of netrin-1 to be important for its interaction with the Ig1/Ig2 domains of UNC5H2. We generate a humanized anti-netrin-1 antibody that disrupts the interaction between netrin-1 and UNC5H2 and triggers death of netrin-1-expressing tumor cells in vitro. We also present evidence that combining the anti-netrin-1 antibody with epidrugs such as decitabine could be effective in treating tumors showing no or modest netrin-1 expression. These results support that this antibody is a promising drug candidate.

Acepromazine pharmacokinetics: a forensic perspective.

Acepromazine (ACP) is a useful therapeutic drug, but is a prohibited substance in competition horses. The illicit use of ACP is difficult to detect due to its rapid metabolism, so this study investigated the ACP metabolite 2-(1-hydroxyethyl)promazine sulphoxide (HEPS) as a potential forensic marker. Acepromazine maleate, equivalent to 30mg of ACP, was given IV to 12 racing-bred geldings. Blood and urine were collected for 7days post-administration and analysed for ACP and HEPS by liquid chromatography-mass spectrometry (LC-MS). Acepromazine was quantifiable in plasma for up to 3h with little reaching the urine unmodified. Similar to previous studies, there was wide variation in the distribution and metabolism of ACP. The metabolite HEPS was quantifiable for up to 24h in plasma and 144h in urine. The metabolism of ACP to HEPS was fast and erratic, so the early phase of the HEPS emergence could not be modelled directly, but was assumed to be similar to the rate of disappearance of ACP. However, the relationship between peak plasma HEPS and the y-intercept of the kinetic model was strong (P=0.001, r(2)=0.72), allowing accurate determination of the formation pharmacokinetics of HEPS. Due to its rapid metabolism, testing of forensic samples for the parent drug is redundant with IV administration. The relatively long half-life of HEPS and its stable behaviour beyond the initial phase make it a valuable indicator of ACP use, and by determining the urine-to-plasma concentration ratios for HEPS, the approximate dose of ACP administration may be estimated.

Gene expression alterations in formalin-fixed, paraffin-embedded Barrett esophagus and esophageal adenocarcinoma tissues.

BACKGROUND AND AIM: Widespread applicability of tissue-based mRNA expression screening for Barrett esophagus (BE) is likely to require (1) accurate methods for assaying archival formalin-fixed, paraffin-embedded (FFPE) histopathology specimens taken at endoscopy, and (2) validation studies of promising biomarkers in different patient cohorts. RESULTS: 30 genes were significantly differentially expressed by histopathology tissue type. The direction and magnitude of the differences were very similar to those found in previous studies using fresh frozen tissues. Novel upregulated genes were TSPAN8 (also known as CO-029), TSPAN24 (CD151), EGR1 and TCIRG1. Novel downregulated genes were DPYD, TSPAN29 (CD9) and Ets1. Strong associations between histopathology type and gene expression were observed with the overexpressed genes: cyclo-oxygenase-2 (COX-2), for which histopathology type explained 77.7% of the variation in expression, TSPAN1 (73.5%), TSPAN8 (62.9%), SPARC (62.1%), MMP7 (50.8%); and the under-expressed genes ADH7 (53.7%), APC (58.2%), RAR-gamma (51.3%). METHODS: mRNA was isolated from 54 FFPE small endoscopic biopsies from patients with Barrett intestinal metaplasia (BE), esophageal adenocarcinoma (EAC), or control patients with a normal squamous-lined esophagus. Multiplexed tandem PCR (MT-PCR) was used to quantitate 50 selected candidate genes for BE and control genes in duplicate. Principal component analysis (PCA) was conducted to explore the presence of global differences in gene expression profiles. One-way analysis of variance (ANOVA) of the transformed data was used to identify genes that were differentially expressed between different histological subtypes. Differentially expressed genes with a fold change of ≥2 (upregulated) or ≤-2 (downregulated) are reported with the p value for each comparison (EAC vs. normal, EAC vs. BE and BE vs. normal). The Benjamini-Hochberg method was used to control the false discovery rate at 0.01 for all comparisons. CONCLUSIONS: Alterations in expression of select genes are strongly associated with BE or EAC or both. This study's findings for many highly differentially expressed genes are very similar to those previously reported, suggesting that these genes should be tested further in longitudinal studies for their potential role as biomarkers of progression to more advanced Barrett disease.

Effectiveness of HSV-tk suicide gene therapy driven by the Grp78 stress-inducible promoter in esophagogastric junction and gastric adenocarcinomas.

BACKGROUND: The thymidine kinase gene of the herpes simplex virus (HSV-tk) is a suicide gene when administrated with the prodrug ganciclovir (GCV). This study investigated the effectiveness of HSV-tk activation as gene therapy for gastroesophageal junction and gastric adenocarcinomas using either the stress-inducible Grp78 promoter or the murine leukemia virus long-terminal repeat (LTR) promoter. METHODS: The HSV-tk gene, controlled by either the Grp78 promoter or the LTR promoter, was transduced into the gastroesophageal junction adenocarcinoma cell line SK-GT-5 and the gastric adenocarcinoma cell line MKN-74. Cell viability after exposure to varying concentrations of GCV was compared. The same cell lines were used to develop a nude mouse model for studies of the HSV-tk/GCV effect in vivo. The effect of intraperitoneal GCV injection on growth of the subcutaneous tumors was measured. HSV-TK expression was measured by Western blot and reverse transcription polymerase chain reaction. RESULTS: Cell viability in vitro was significantly lower in the HSV-tk expressing (HSV-tk+) cells compared to control (no HSV-tk) cells after exposure to GCV. MKN-74tk+ cells were more sensitive to GCV killing than SK-GT-5tk+ cells. After culture with 1 microg/ml GCV for 10 days, MKN-74/tk cells were totally killed, whereas most SK-GT-5/tk cells survived. Cell viability was significantly lower under glucose starvation conditions when HSV-tk expression was regulated by the Grp78 promoter compared with the LTR promoter. MKN-74 tumors formed with HSV-tk+ cells in nude mice were eliminated after administration of GCV for 3 weeks, but GCV had no effect on tumors formed from HSV-tk- cells. Eradication of tumor formed with Grp78-tk cells was faster than that with LTR-tk cells. HSV-TK protein and mRNA were expressed in the transduced, but not the non-transduced tumors. CONCLUSION: HSV-tk xwith ganciclovir suicide gene therapy results in significant cell killing in gastroesophageal junction and gastric adenocarcinoma cells both in vitro and in vivo, but complete tumor elimination only occurred with the gastric adenocarcinoma cell tumors. The most effective approach in this study used the Grp78 promoter in glucose-starvation stress conditions.

Binding of netrin-4 to laminin short arms regulates basement membrane assembly.

Netrins were first identified as neural guidance molecules, acting through receptors that are members of the DCC and UNC-5 family. All netrins share structural homology to the laminin N-terminal domains and the laminin epidermal growth factor-like domains of laminin short arms. Laminins use these domains to self-assemble into complex networks. Here we demonstrate that netrin-4 is a component of basement membranes and is integrated into the laminin polymer via interactions with the laminin gamma1 andgamma3 short arms. The binding is mediated through the laminin N-terminal domain of netrin-4. In contrast to netrin-4, other members of the netrin family do not bind to these laminin short arms. Moreover, a truncated form of netrin-4 completely inhibits laminin-111 self-assembly in vitro, and full-length netrin-4 can partially disrupt laminin self-interactions. When added to explant cultures, netrin-4 retards salivary gland branching morphogenesis.