A HAMP promoter bioassay system for identifying chemical compounds that modulate hepcidin expression

Hepcidin Promoted Ferroptosis through Iron Metabolism which Is Associated with DMT1 Signaling Activation in Early Brain Injury following Subarachnoid Hemorrhage

Iron metabolism disturbances play an important role in early brain injury (EBI) after subarachnoid hemorrhage (SAH), and hepcidin largely influences iron metabolism. Importantly, iron metabolism may be associated with ferroptosis, recently a nonapoptotic iron-dependent form of cell death that may have a great impact on brain injury after SAH. We investigated hepcidin on iron metabolism and ferroptosis involving divalent metal transporter 1 (DMT1), and ferroportin-1 (FPN1) in a rat model of SAH. Male Sprague-Dawley rats were subjected to the endovascular perforation to induce SAH, and treated with heparin (inhibitor of hepcidin), or oncostatin M (OSM, inducer of hepcidin), or ebselen (inhibitor of DMT1) by intracerebroventricular injections. Hepcidin, DMT1, FPN1 and glutathione peroxidase 4 (GPX4), were detected by western blot and immunofluorescence. Iron metabolism was detected through Perl's iron staining and iron content assay. Ferroptosis, the ROS production, lipid peroxidation (LPO) was evaluated by monitoring methane dicarboxylic aldehyde (MDA), glutathione (GSH), glutathione peroxidase 4 (GPX4) activity, and transmission electron microscopy. Neurological deficit scores, Evans blue staining and brain water content were also determined to detect EBI 72 h after SAH. Our results showed that inhibition of DMT1 by ebselen could suppress iron accumulation and lipid peroxidation, and thereby alleviate ferroptosis and EBI in SAH rats. Heparin downregulated the expression of hepcidin and DMT1, increased FPN1, and exerted protective effects that were equivalent to those of ebselen on ferroptosis and EBI. In addition, OSM increased the expression of hepcidin and DMT1, decreased FPN1, and aggravated ferroptosis and EBI, while the effect on ferroptosis was reversed by ebselen. Therefore, the study revealed that hepcidin could regulate iron metabolism and contribute to ferroptosis via DMT1 signaling activation in rats with EBI after SAH.

A high-throughput screening to identify small molecules that suppress huntingtin promoter activity or activate huntingtin-antisense promoter activity

Huntington’s disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in exon 1 of huntingtin (HTT). While there are currently no disease-modifying treatments for HD, recent efforts have focused on the development of nucleotide-based therapeutics to lower HTT expression. As an alternative to siRNA or oligonucleotide methods, we hypothesized that suppression of HTT expression might be accomplished by small molecules that either (1) directly decrease HTT expression by suppressing HTT promoter activity or (2) indirectly decrease HTT expression by increasing the promoter activity of HTT-AS, the gene antisense to HTT that appears to inhibit expression of HTT. We developed and employed a high-throughput screen for modifiers of HTT and HTT-AS promoter activity using luminescent reporter HEK293 cells; of the 52,041 compounds tested, we identified 898 replicable hits. We used a rigorous stepwise approach to assess compound toxicity and the capacity of the compounds to specifically lower huntingtin protein in 5 different cell lines, including HEK293 cells, HD lymphoblastoid cells, mouse primary neurons, HD iPSCs differentiated into cortical-like neurons, and HD hESCs. We found no compounds which were able to lower huntingtin without lowering cell viability in all assays, though the potential efficacy of a few compounds at non-toxic doses could not be excluded. Our results suggest that more specific targets may facilitate a small molecule approach to HTT suppression.

Increased expression of hepcidin and associated upregulation of JAK/STAT3 signaling in human gastric cancer

Gastric cancer is one of the most common malignancies with high cancer-associated mortality rate globally. Hepcidin is the peptide hormone, which is critically important in the regulation of systemic iron homeostasis. Cumulating evidence has reported that the disturbed local expression of hepcidin may serve as a predictive biomarker in assessing the clinical outcomes in a range of cancer types. However, the expression profile of hepcidin in human gastric cancer is remains to be investigated. In the present retrospective study, using archived paraffin-embedded tissue blocks, the local production of hepcidin by immunohistochemical analysis was detected, and then its correlation with clinicopathological characteristics in human gastric cancer was evaluated. In parallel, using western blotting, quantitative reverse transcription polymerase chain reaction and chromatin immunoprecipitation assay, the local status of Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling in response to inflammatory stimuli mediated by interleukin (IL)-6, which in turn regulates transcriptional activity of hepcidin gene (HAMP) was also assessed. The results indicated that, the local production of hepcidin was significantly elevated in tumor tissues compared with adjacent non-tumor tissues, and was tightly correlated with increasing tumor stages according to the tumor node metastasis (TNM) classification. In addition, JAK/STAT3 signaling and the STAT3 binding affinity to the HAMP gene promoter were significantly enhanced, in parallel with an increased expression of hepcidin, in tumor tissues compared with adjacent non-tumor tissues. Collectively, the present study indicated that local expression of hepcidin in gastric cancer tumor tissues was positively correlated with increasing tumor stages, which may be closely associated with the upregulation of IL-6-mediated JAK/STAT3 signaling in human gastric cancer.