Disulfiram treatment suppresses antibody-producing reactions by inhibiting macrophage activation and B cell pyrimidine metabolism.

Antibody responses, involving B cells, CD4 + T cells, and macrophages, are implicated in autoimmune diseases and organ transplant rejection. We have previously shown that inhibiting FROUNT with disulfiram (DSF) suppresses macrophage activation and migration, effectively treating inflammatory diseases. In this study, we investigated the effectiveness of DSF in antibody-producing reactions. Using a heart transplantation mouse model with antibody-mediated rejection, we administered anti-CD8 antibody to exclude cellular rejection. DSF directly inhibited B cell responses in vitro and significantly reduced plasma donor-specific antibodies and graft antibody deposition in vivo, resulting in prolonged survival of the heart graft. DSF also mediated various effects, including decreased macrophage infiltration and increased Foxp3+ regulatory T-cells in the grafts. Additionally, DSF inhibited pyrimidine metabolism-related gene expression induced by B-cell stimulation. These findings demonstrate that DSF modulates antibody production in the immune response complexity by regulating B-cell and macrophage responses.

Inhibition of the chemokine signal regulator FROUNT by disulfiram ameliorates crescentic glomerulonephritis.

Activated monocytes/macrophages promote glomerular injury, including crescent formation, in anti-glomerular basement membrane (GBM) glomerulonephritis. Disulfiram, an alcohol-aversion drug, inhibits monocyte/macrophage migration by inhibiting FROUNT, a cytosolic protein that enhances chemokine receptor signaling. Our study found that disulfiram at a human equivalent dose successfully blocked albuminuria and crescent formation with podocyte loss, and later stage kidney fibrotic lesions, in a rat model of anti-GBM glomerulonephritis. A disulfiram derivative, DSF-41, with more potent FROUNT inhibition activity, inhibited glomerulonephritis at a lower dose than disulfiram. Disulfiram markedly reduced the number of monocytes or macrophages at the early stage of glomerulonephritis and that of CD3+ and CD8+ lymphocytes at the established stage. Impaired pseudopodia formation was observed in the glomerular monocytes/macrophages of the disulfiram group; consistent with the in vitro observation that disulfiram blocked chemokine-dependent pseudopodia formation and chemotaxis of bone marrow-derived monocytes/macrophages. Furthermore, disulfiram suppressed macrophage activation as revealed by reduced expression of inflammatory cytokines and chemokines (TNF-α, CCL2, and CXCL9) and reduced CD86 and MHC class II expressions in monocytes/macrophages during glomerulonephritis. The dramatic reduction in monocyte/macrophage number might have resulted from disulfiram suppression of both the chemotactic response of monocytes/macrophages and their subsequent activation to produce cytokines and chemokines, which further recruit monocytes. Additionally, FROUNT was expressed in CD68+ monocytes/macrophages infiltrating the crescentic glomeruli in human anti-GBM glomerulonephritis. Thus, disulfiram can be a highly effective and safe drug for the treatment of glomerulonephritis by blocking the chemotactic responses of monocytes/macrophages and their activation status in the glomerulus.

The miR-1908/SRM regulatory axis contributes to extracellular vesicle secretion in prostate cancer.

Targeting extracellular vesicle (EV) secretion can have potential clinical implications for cancer therapy, however the precise regulatory mechanisms of EV secretion are not fully understood. Recently, we have shown a novel pathway of EV biogenesis in PCa cell lines, PC3 and PC3M. However, as the characteristics of EVs are divergent even among PCa cell lines, we hypothesized that other pathways or common regulatory pathways of EV biogenesis still exist. Here, we performed quantitative high-throughput screening to determine the key regulatory genes involved in EV biogenesis in 22Rv1 cells, which secrete a different type of EVs. In total, 1728 miRNAs were screened and miR-1908 was selected as the potential miRNA regulating EV biogenesis in 22Rv1 cells. Subsequently, we investigated target genes of miR-1908 using siRNA screening and identified that spermidine synthase (SRM) was the key regulator of EV secretion in 22Rv1 cells. Attenuation of SRM expression significantly inhibited secretion of EVs in 22Rv1 cells, and overexpression of SRM was confirmed in PCa tissues. Furthermore, we found that the number of endosome compartments was increased in cellular cytoplasm after knockdown of the SRM gene. In conclusion, our results showed that miR-1908-mediated regulation of SRM can control secretion of EVs in PCa. In addition, these data suggested that the EV secretion pathway was dependent on cellular characteristics.

miR-26a regulates extracellular vesicle secretion from prostate cancer cells via targeting SHC4, PFDN4, and CHORDC1.

Extracellular vesicles (EVs) are involved in intercellular communication during cancer progression; thus, elucidating the mechanism of EV secretion in cancer cells will contribute to the development of an EV-targeted cancer treatment. However, the biogenesis of EVs in cancer cells is not fully understood. MicroRNAs (miRNAs) regulate a variety of biological phenomena; thus, miRNAs could regulate EV secretion. Here, we performed high-throughput miRNA-based screening to identify the regulators of EV secretion using an ExoScreen assay. By using this method, we identified miR-26a involved in EV secretion from prostate cancer (PCa) cells. In addition, we found that SHC4, PFDN4, and CHORDC1 genes regulate EV secretion in PCa cells. Furthermore, the progression of the PCa cells suppressing these genes was inhibited in an in vivo study. Together, our findings suggest that miR-26a regulates EV secretion via targeting SHC4, PFDN4, and CHORDC1 in PCa cells, resulting in the suppression of PCa progression.

Radiation Exposure Enhances Hepatocyte Proliferation in Neonatal Mice but not in Adult Mice.

There is a natural tendency to expect that irradiation of an infant organ prior to development-related expansion will result in a higher risk of developing cancer than that of fully-developed adult tissue, and this has generally been observed. However, if tissues also vary in their initial responses to radiation depending on age, the interplay between tissue- and age-dependent risk would potentially be quite complex. We have previously shown opposing age-dependent induction of apoptosis for the intestinal epithelium and hematopoietic cells in mice, but such data are not yet available for the liver. Here, we have examined markers of DNA damage, initiation of DNA damage responses, cell cycle arrest, apoptosis and proliferation, as well as gene expression, in the B6C3F1 mouse liver over the hours and days after irradiation of mice at 1 or 7 weeks of age. We found that induction and resolution of radiation-induced DNA damage is not accompanied by significant changes in these cellular end points in the adult liver, while in infant hepatocytes modest induction of p53 accumulation and p21-mediated cell cycle arrest in a small fraction of damaged cells was overshadowed by a further stimulation of proliferation over the relatively high levels already found in the neonatal liver. We observed distinct expression of genes that regulate cell division between the ages, which may contribute to the differential responses. These data suggest that the growth factor signaling environment of the infant liver may mediate radiation-induced proliferation and increased liver cancer risk after irradiation during early life.