High grade serous ovarian cancer (OvCa) frequently becomes drug resistant and often recurs. Consequently, new drug targets and therapies are needed. Bioinformatics-based studies uncovered a relationship between high Protein Tyrosine Phosphatase of Regenerating Liver-3 (PRL3 also known as PTP4A3) expression and poor patient survival in both early and late stage OvCa. PTP4A3 mRNA levels were 5–20 fold higher in drug resistant or high grade serous OvCa cell lines compared to nonmalignant cells. JMS-053 is a potent allosteric small molecule PTP4A3 inhibitor and to explore further the role of PTP4A3 in OvCa, we synthesized and interrogated a series of JMS-053-based analogs in OvCa cell line-based phenotypic assays. While the JMS-053 analogs inhibit in vitro PTP4A3 enzyme activity, none were superior to JMS-053 in reducing high grade serous OvCa cell survival. Because PTP4A3 controls cell migration, we interrogated the effect of JMS-053 on this cancer-relevant process. Both JMS-053 and CRISPR/Cas9 PTP4A3 depletion blocked cell migration. The inhibition caused by JMS-053 required the presence of PTP4A3. JMS-053 caused additive or synergistic in vitro cytotoxicity when combined with paclitaxel and reduced in vivo OvCa dissemination. These results indicate the importance of PTP4A3 in OvCa and support further investigations of the lead inhibitor, JMS-053.

Neurogenesis is a complex process encompassing neuronal progenitor cell expansion/proliferation and differentiation, followed by neuron maturation. In vivo models are most commonly used to study neurogenesis; however, human induced pluripotent stem cell-derived (iPSC) neurons are increasingly used to establish cellular models of human neurological processes. Unfortunately, the differentiation and maturation of iPSC-derived neurons varies in methodology, is asynchronous, and has restricted experimental utility because of extended differentiation/maturation times. To accelerate and standardize iPS neuronal maturation, we differentiated and matured feeder layer-free iPSC-derived neuronal cultures under physiological oxygen levels (5%), and modified the underlying extracellular matrix and medium composition. Our results demonstrate that calretinin gene expression occurred earlier under our optimized iPS conditions and the corresponding neurogenesis burst associated with proliferative expansion occurred more synchronously, reliably emerging two and three weeks after differentiation. As expected, the expression of mature neuronal markers (i.e., NeuN+/Calbindin+) started at 4-weeks post-differentiation. qPCR microarray, western blot and single cell analyses using high content imaging indicated that 4-week iPS neuronal cultures were non-cycling with decreased expression of cyclin D1 and Ki67. Our data demonstrate that extracellular cues influence the kinetics of neurogenesis models and that feeder layer-free iPSC-derived neurogenesis can be reproducibly miniaturized.

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Successful medicinal chemistry campaigns to discover and optimize sphingosine kinase inhibitors require a robust assay for screening chemical libraries and for determining rank order potencies. Existing assays for these enzymes are laborious, expensive and/or low throughput. The toxicity of excessive levels of phosphorylated sphingoid bases for the budding yeast, Saccharomyces cerevisiae, affords an assay wherein inhibitors added to the culture media rescue growth in a dose-dependent fashion. Herein, we describe our adaptation of a simple, inexpensive, and high throughput assay for assessing inhibitors of sphingosine kinase types 1 and 2 as well as ceramide kinase and for testing enzymatic activity of sphingosine kinase type 2 mutants. The assay was validated using recombinant enzymes and generally agrees with the rank order of potencies of existing inhibitors.

Human induced pluripotent stem cell‐derived (iPSC) neurons are increasingly being used as a platform for neurological disease modeling, high throughput/content screening and drug discovery. However, the differentiation and maturation of iPSC‐derived neurons is not standardized and varies in methodology (i.e., timing) limiting their usefulness in automated drug screening platforms. To generate mature iPS‐derived neurons for high content screening, we derived neuronal progenitor cells (NPCs) from the normal iPSC control lines, 7545‐5b and 7753, using monolayer derivation methods. We differentiated these NPCs under environmental oxygen (21%) conditions and discerned that mature neuronal markers were predominantly expressed by 12 weeks post‐differentiation. When we differentiated and matured 7753‐ and 7545‐derived neuronal cultures under physiological (5%) oxygen levels, however, iPS neuronal maturation was markedly accelerated with increased gene and protein expression of mature neuronal markers (i.e., calretinin, calbindin, NeuN) being seen at 6 weeks post differentiation. Further modifications of the underlying extracellular matrix (i.e., poly‐D‐ornithine, laminin), and medium composition and transition shifted the expression of mature neuronal markers to 4 weeks post‐differentiation. This coincided with the cessation of the neurogenesis burst which occurred between weeks 2 and 3 post‐differentiation. qPCR microarray and western blot data as well as single cell analyses showed that 4 week iPS neuronal cultures were non‐cycling with decreased expression of cyclin D1 and Ki67. Further optimization of cell seeding density and incubations ameliorated edge effects associated with prolonged cell culturing. Taken together, we have developed conditions for the derivation of a mature iPSC‐derived neurons in 4 weeks, which are amenable to high throughput and high content screening applications.