Background:Eribulin mesilate (eribulin), a non-taxane microtubule dynamics inhibitor, has shown trends towards greater overall survival (OS) compared with progression-free survival in late-stage metastatic breast cancer patients in the clinic. This finding suggests that eribulin may have additional, previously unrecognised antitumour mechanisms beyond its established antimitotic activity. To investigate this possibility, eribulin's effects on the balance between epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition (MET) in human breast cancer cells were investigated.Methods:Triple negative breast cancer (TNBC) cells, which are oestrogen receptor (ER−)/progesterone receptor (PR−)/human epithelial growth receptor 2 (HER2−) and have a mesenchymal phenotype, were treated with eribulin for 7 days, followed by measurement of EMT-related gene and protein expression changes in the surviving cells by quantitative real-time PCR (qPCR) and immunoblot, respectively. In addition, proliferation, migration, and invasion assays were also conducted in eribulin-treated cells. To investigate the effects of eribulin on TGF-β/Smad signalling, the phosphorylation status of Smad proteins was analysed. In vivo, the EMT/MET status of TNBC xenografts in mice treated with eribulin was examined by qPCR, immunoblot, and immunohistochemical analysis. Finally, an experimental lung metastasis model was utilised to gauge the metastatic activity of eribulin-treated TNBC in the in vivo setting.Results:Treatment of TNBC cells with eribulin in vitro led to morphological changes consistent with transition from a mesenchymal to an epithelial phenotype. Expression analyses of EMT markers showed that eribulin treatment led to decreased expression of several mesenchymal marker genes, together with increased expression of several epithelial markers. In the TGF-β induced EMT model, eribulin treatment reversed EMT, coincident with inhibition of Smad2 and Smad3 phosphorylation. Consistent with these changes, TNBC cells treated with eribulin for 7 days showed decreased capacity for in vitro migration and invasiveness. In in vivo xenograft models, eribulin treatment reversed EMT and induced MET as assessed by qPCR, immunoblot, and immunohistochemical analyses of epithelial and mesenchymal marker proteins. Finally, surviving TNBC cells pretreated in vitro with eribulin for 7 days led to decreased numbers of lung metastasis when assessed in an in vivo experimental metastasis model.Conclusions:Eribulin exerted significant effects on EMT/MET-related pathway components in human breast cancer cells in vitro and in vivo, consistent with a phenotypic switch from mesenchymal to epithelial states, and corresponding to observed decreases in migration and invasiveness in vitro as well as experimental metastasis in vivo. These preclinical findings may provide a plausible scientific basis for clinical observations of prolonged OS by suppression of further spread of metastasis in breast cancer patients treated with eribulin.

Disrupted in schizophrenia 1 (DISC1), a genetic risk factor for multiple serious psychiatric diseases including schizophrenia, bipolar disorder and autism, is a key regulator of multiple neuronal functions linked to both normal development and disease processes. As these diseases are thought to share a common deficit in synaptic function and architecture, we have analyzed the role of DISC1 using an approach that focuses on understanding the protein– protein interactions of DISC1 specifically at synapses. We identify the Traf2 and Nck-interacting kinase (TNIK), an emerging risk factor itself for disease, as a key synaptic partner for DISC1, and provide evidence that the DISC1–TNIK interaction regulates synaptic composition and activity by stabilizing the levels of key postsynaptic density proteins. Understanding the novel DISC1–TNIK interaction is likely to provide insights into the etiology and underlying synaptic deficits found in major psychiatric diseases.

The high prevalence of mental disorders such as depression and dementia in institutionalized elderly patients warrants screening for psychiatric diagnosis in patients newly admitted to long-term care facilities. The diagnostic accuracy of the Mini-Mental State Examination (MMSE) and the Geriatric Depression Scale (GDS) was evaluated against a standardized psychiatric interview. The MMSE was found to be 81% sensitive and 83% specific in screening for dementia using a previously established cutpoint of less than 24/30 points. Adjusting MMSE scores for physical disabilities precluding completion of specific tasks on the MMSE did not significantly change the diagnostic accuracy of the test. The GDS was 47% sensitive and 75% specific in screening for depression using the suggested cutpoint of greater than 13/30 points. The MMSE was significantly correlated with functional status (r = 0.48, P = .0001), but not with the scores on the GDS or the clinical diagnosis of depression. The GDS did not correlate with functional status. In summary, the MMSE is a good screening test for dementia in institutionalized elderly, but the GDS is not sensitive for depression in this population.

Abbreviations: SA-J schweinfurthin A-J; TGN trans-Golgi-network; PTEN phosphatase and tensin homolog; DLBCL diffuse large B cell lymphoma; mTOR mammalian target of rapamycin; PDK1 phosphoinositide-dependent kinase 1; PIP3 phosphatidylinositol (3,4,5)-triphosphate; WGA wheat germ agglutinin; ConA concanavalin; MAA Maackia amurensis agglutinin; PNA peanut agglutinin; ORPs oxysterol-binding protein related family proteins Natural compound schweinfurthins are of considerable interest for novel therapy development because of their selective anti-proliferative activity against human cancer cells. We previously reported the isolation of highly active schweinfurthins E-H, and in the present study, mechanisms of the potent and selective anti-proliferation were investigated. We found that schweinfurthins preferentially inhibited the proliferation of PTEN deficient cancer cells by indirect inhibition of AKT phosphorylation. Mechanistically, schweinfurthins and their analogs arrested trans-Golginetwork trafficking, an intracellular vesicular trafficking system, resulting in the induction of endoplasmic reticulum stress and the suppression of both lipid raft-mediated PI3K activation and mTOR/RheB complex formation, which collectively led to an effective inhibition of mTOR/AKT signaling. The trans-Golgi-network traffic arresting effect of schweinfurthins was associated with their in vitro binding activity to oxysterol-binding proteins that are known to regulate intracellular vesicular trafficking. Moreover, schweinfurthins were found to be highly toxic toward PTENdeficient B cell lymphoma cells, and displayed 2 orders of magnitude lower activity toward normal human peripheral blood mononuclear cells and primary fibroblasts in vitro. These results revealed a previously unrecognized role of schweinfurthins in regulating trans-Golgi-network trafficking, and linked mechanistically this cellular effect with mTOR/ AKT signaling and with cancer cell survival and growth. Our findings suggest the schweinfurthin class of compounds as a novel approach to modulate oncogenic mTOR/AKT signaling for cancer treatment.

BackgroundEribulin mesylate is a synthetic macrocyclic ketone analog of the marine sponge natural product halichondrin B. Eribulin is a tubulin-binding drug and approved in many countries worldwide for treatment of certain patients with advanced breast cancer. Here we investigated antiproliferative and antiangiogenic effects of eribulin on vascular cells, human umbilical vein endothelial cells (HUVECs) and human brain vascular pericytes (HBVPs), in vitro in comparison with another tubulin-binding drug, paclitaxel.MethodsHUVECs and HBVPs were treated with either eribulin or paclitaxel and their antiproliferative effects were evaluated. Global gene expression profiling changes caused by drug treatments were studied using Affymetrix microarray platform and custom TaqMan Low Density Cards. To examine effects of the drugs on pericyte-driven in vitro angiogenesis, we compared lengths of capillary networks in co-cultures of HUVECs with HBVPs.ResultsBoth eribulin and paclitaxel showed potent activities in in vitro proliferation of HUVECs and HBVPs, with the half-maximal inhibitory concentrations (IC50) in low- to sub-nmol/L concentrations. When gene expression changes were assessed in HUVECs, the majority of affected genes overlapped for both treatments (59%), while in HBVPs, altered gene signatures were drug-dependent and the overlap was limited to just 12%. In HBVPs, eribulin selectively affected 11 pathways (p < 0.01) such as Cell Cycle Control of Chromosomal Replication. In contrast, paclitaxel was tended to regulate 27 pathways such as PI3K/AKT. Only 5 pathways were commonly affected by both treatments. In in vitro pericyte-driven angiogenesis model, paclitaxel showed limited activity while eribulin shortened the formed capillary networks of HUVECs driven by HBVPs at low nmol/L concentrations starting at day 3 after treatments.ConclusionsOur findings suggest that pericytes, but not endothelial cells, responded differently, to two mechanistically-distinct tubulin-binding drugs, eribulin and paclitaxel. While eribulin and paclitaxel induced similar changes in gene expression in endothelial cells, in pericytes their altered gene expression was unique and drug-specific. In the functional endothelial-pericyte co-culture assay, eribulin, but not paclitaxel showed strong efficacy not only as a cytotoxic drug but also as a potent antivascular agent that affected pericyte-driven in vitro angiogenesis.