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Isolation of tumor-initiating cells currently relies on markers that do not reflect essential biologic functions of these cells. We proposed to overcome this limitation by isolating tumor-initiating cells based on enhanced migration, a function tightly linked to tumor-initiating potential through epithelial-to-mesenchymal transition (EMT). We developed a high-throughput microfluidic migration platform with automated cell tracking software and facile recovery of cells for downstream functional and genetic analyses. Using this device, we isolated a small subpopulation of migratory cells with significantly greater tumor formation and metastasis in mouse models. Whole transcriptome sequencing of migratory versus non-migratory cells from two metastatic breast cancer cell lines revealed a unique set of genes as key regulators of tumor-initiating cells. We focused on phosphatidylserine decarboxylase (PISD), a gene downregulated by 8-fold in migratory cells. Breast cancer cells overexpressing PISD exhibited reduced tumor-initiating potential in a high-throughput microfluidic mammosphere device and mouse xenograft model. PISD regulated multiple aspects of mitochondria, highlighting mitochondrial functions as therapeutic targets against cancer stem cells. This research establishes not only a novel microfluidic technology for functional isolation of tumor-initiating cells regardless of cancer type, but also a new approach to identify essential regulators of these cells as targets for drug development.

Activation of microglial cells is presumed to play a key role in the pathogenesis of Parkinson's disease (PD). The activity of microglia is regulated by the histamine-4 receptor (H4R), thus providing a novel target to prevent the progression of PD. However, this putative mechanism has so far not been validated. In our previous post-mortem study, we found that mRNA expression of H4R was upregulated in the basal ganglia of PD patients. In the present study, we found indeed an upregulation of microglia associated inflammation markers from microarray data of the substantia nigra pars compacta (SNpc) of PD patients. We validated the mechanism underlying our human PD results using the rotenone-induced PD rat model, in which the expression of H4R and microglial markers mRNA were significantly increased in the SNpc. Inhibition of H4R in rotenone-induced rats by infusion of the specific H4R antagonist JNJ7777120 into the left lateral ventricle blocked microglial activation, reduced apomorphine-induced rotational behaviour, and prevented dopaminergic neuron degeneration and associated decreases in striatal dopamine levels. These changes were accompanied by a reduction of Lewy body-like neuropathology. Our results provide first proof of the efficacy of an H4R antagonist in a commonly used 3 PD rat model, and provides a lead for a promising therapeutic strategy aimed at modifying H4R activation to clinically tackle microglial activation and thereby the progression of PD.