Selective targeting of cancer stem cells (CSCs) offers promise for a new generation of therapeutics. However, assays for both human CSCs and normal stem cells that are amenable to robust biological screens are limited. Using a discovery platform that reveals differences between neoplastic and normal human pluripotent stem cells (hPSC), we identify small molecules from libraries of known compounds that induce differentiation to overcome neoplastic self-renewal. Surprisingly, thioridazine, an antipsychotic drug, selectively targets the neoplastic cells, and impairs human somatic CSCs capable of in vivo leukemic disease initiation while having no effect on normal blood SCs. The drug antagonizes dopamine receptors that are expressed on CSCs and on breast cancer cells as well. These results suggest that dopamine receptors may serve as a biomarker for diverse malignancies, demonstrate the utility of using neoplastic hPSCs for identifying CSC-targeting drugs, and provide support for the use of differentiation as a therapeutic strategy.

Although N-and P-type Ca 2؉ channels predominant in fast-secreting systems, Lc-type Ca 2؉ channels (C-class) can play a similar role in certain secretory cells and synapses. For example, in retinal bipolar cells, Ca 2؉ entry through the Lc channels triggers ultrafast exocytosis, and in pancreatic ␤-cells, evoked secretion is highly sensitive to Ca 2؉ . These findings suggest that a rapidly release pool of vesicles colocalizes with the Ca 2؉ channels to allow high Ca 2؉ concentration and a tight coupling of the Lc channels at the release site. In binding studies, we show that the Lc channel is physically associated with synaptotagmin (p65) and the soluble N-ethylmaleimide-sensitive attachment proteins receptors: syntaxin and synaptosomal-associated protein of 25 kDa. Soluble N-ethylmaleimide-sensitive attachent proteins receptors coexpressed in Xenopus oocytes along with the Lc channel modify the kinetic properties of the channel. The modulatory action of syntaxin can be overcome by coexpressing p65, where at a certain ratio of p65͞syntaxin, the channel regains its unaltered kinetic parameters. The cytosolic region of the channel, Lc 753-893 , separating repeats II-III of its ␣1C subunit, interacts with p65 and ''pulls'' down native p65 from rat brain membranes. Lc 753-893 injected into single insulinsecreting ␤-cell, inhibits secretion in response to channel opening, but not in response to photolysis of caged Ca 2؉ , nor does it affect Ca 2؉ current. These results suggest that Lc 753-893 competes with the endogenous channel for the synaptic proteins and disrupts the spatial coupling with the secretory apparatus. The molecular organization of the Lc channel and the secretory machinery into a multiprotein complex (named excitosome) appears to be essential for an effective depolarization evoked exocytosis.Regulated secretion in synapses occurs at a fast speed from vesicles preassembled with N-and P-type voltage sensitive Ca 2ϩ channels (1). In contrast, in many neuroendocrine cells exocytosis triggered by Ca 2ϩ entry through Lc channel, is slower and persists for tens of milliseconds after Ca 2ϩ influx has stopped, implying that the vesicles are localized at a distance from the source of Ca 2ϩ entry (2-4). Although exocytosis is slow in various endocrine cells in which secretion is mediated by Lc channel (C-class), there are reports suggesting a close association of Lc channels with the exocytotic machinery (5-8). For example a combined study of amperometry and laser imaging in chromaffin cells have shown that the sites of Ca 2ϩ entry and catecholamine release are close (5, 6). Similarly, in mouse pancreatic ␤-cells, Lc channels have been shown to colocalize with insulin-containing secretory granules (7). Previously, we showed that the expression of syntaxin, synaptosomal-associated protein of 25 kDa (SNAP-25), and p65 along with the L-and N-type channel modify the kinetic properties of the channels (8-10). The N-type Ca 2ϩ channel binds syntaxin and SNAP-25 (11-14) at a site in the cytoplasmic domain of ␣1...

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Targeting of human cancer stem cells (CSCs) requires the identification of vulnerabilities unique to CSCs versus healthy resident stem cells (SCs). Unfortunately, dysregulated pathways that support transformed CSCs, such as Wnt/β-catenin signaling, are also critical regulators of healthy SCs. Using the ICG-001 and CWP family of small molecules, we reveal Sam68 as a previously unappreciated modulator of Wnt/β-catenin signaling within CSCs. Disruption of CBP-β-catenin interaction via ICG-001/CWP induces the formation of a Sam68-CBP complex in CSCs that alters Wnt signaling toward apoptosis and differentiation induction. Our study identifies Sam68 as a regulator of human CSC vulnerability.

Abstract

A sequential pattern of interactions of trans-acting factors in rat liver with the phosphoenolpyruvate carboxykinase promoter during late development was observed. A liver-enriched factor, possibly AF1, interacted with the promoter in fetal liver, whereas a factor with the characteristics of C/EBP bound the promoter after birth with the onset of the gene expression.

Pathogen inactivation of platelet concentrates reduces the risk for blood-borne infections. However, its effect on platelet function and hemostatic efficacy of transfusion is unclear. We conducted a randomized noninferiority trial comparing the efficacy of pathogen-inactivated platelets using riboflavin and UV B illumination technology (intervention) compared with standard plasma-stored platelets (control) for the prevention of bleeding in patients with hematologic malignancies and thrombocytopenia. The primary outcome parameter was the proportion of transfusion-treatment periods in which the patient had grade 2 or higher bleeding, as defined by World Health Organization criteria. Between November 2010 and April 2016, 469 unique patients were randomized to 567 transfusion-treatment periods (283 in the control arm, 284 in the intervention arm). There was a 3% absolute difference in grade 2 or higher bleeding in the intention-to-treat analysis: 51% of the transfusion-treatment periods in the control arm and 54% in the intervention arm (95% confidence interval [CI], -6 to 11; = .012 for noninferiority). However, in the per-protocol analysis, the difference in grade 2 or higher bleeding was 8%: 44% in the control arm and 52% in the intervention arm (95% CI -2 to 18; = .19 for noninferiority). Transfusion increment parameters were ∼50% lower in the intervention arm. There was no difference in the proportion of patients developing HLA class I alloantibodies. In conclusion, the noninferiority criterion for pathogen-inactivated platelets was met in the intention-to-treat analysis. This finding was not demonstrated in the per-protocol analysis. This trial was registered at The Netherlands National Trial Registry as #NTR2106 and at www.clinicaltrials.gov as #NCT02783313.