TBK1 Inhibitor Exerts Antiproliferative Effect on Glioblastoma Multiforme Cells

Glioma are common malignant brain tumors, among which glioblastoma multiforme (GBM) has the worst prognosis. Different studies of GBM revealed that targeting nuclear factor B (NF-B) induced an attenuation tumor proliferation and prolonged cell survival. TBK1 {TANK [TRAF (TNF (tumor-necrosis-factor) receptor-associated factor)-associated NF-B activator]-binding kinase 1} is a serine/threonine protein kinase, and it is a member of the IB kinase (IKK) family involved in NF-B pathway activation. The aim of this study was to investigate the potential effect of BX795, an inhibitor of TBK1, in an in vitro and ex vivo model of GBM. GBM cell lines (U87 and U138) and primary GBM cells were treated with different concentrations of BX795 at different time points (24, 48, and 72h) to evaluate cell viability, autophagy, inflammation, and apoptosis. Our results demonstrated that BX795 10 M was able to reduce cell viability, showing antiproliferative effect in U87, U138, and primary GBM cells. Moreover, treatment with BX795 10 M increased the proapoptotic proteins Bax, p53, caspase 3, and caspase 9, whereas the antiapoptotic Bcl-2 expression was reduced. Additionally, our results showed a marked decrease in autophagy following BX795 treatment, reducing Atg 7, Atg 5/12, and AKT expression. The anti-inflammatory effect of BX795 was demonstrated by a significantly reduction in NIK, IKK, and TNF- expression, accompanied by a downregulation of angiogenesis. Furthermore, in primary GBM cell, BX795 10 M was able to reduce TBK1 pathway activation and SOX3 expression. In conclusion, these findings showed that TBK1 is involved in GBM proliferation, demonstrating that the inhibitor BX795, thanks to its abilities, could improve therapeutic strategies for GBM treatment.

Lack of Vitamin D Receptor Leads to Hyperfunction of Claudin-2 in Intestinal Inflammatory Responses

BACKGROUND

Vitamin D3 and vitamin D receptor (VDR) are involved in the pathogenesis of inflammatory bowel disease (IBD) and bacterial infection. Claudin-2 is a junction protein that mediates paracellular water transport in epithelia. Elevation of Claudin-2 is associated with active IBD. However, VDR involved in epithelial junctions under inflammation and infection remains largely unknown. We investigated the mechanisms on how VDR and Claudin-2 are related in inflamed states.

METHODS

Using cultured VDR-/- enteroids, human intestinal epithelial cells, VDR-/- mice with Salmonella- or DSS-colitis, and human IBD samples, we investigated the mechanisms how VDR and Claudin-2 are related in inflamed states.

RESULTS

After Salmonella infection had taken place, we observed significantly enhanced Claudin-2 and an increased bacterial invasion and translocation. A lack of VDR regulation led to a robust increase of Claudin-2 at the mRNA and protein levels post-infection. In DSS-treated VDR-/- mice, Claudin-2 was significantly increased. Location and quantification of Claudin-2 protein in the mouse colons treated with DSS also confirmed these results. Inflammatory cytokines were significantly higher in the serum and mRNA levels in intestine, which are known to increase Claudin-2. Furthermore, in inflamed intestine of ulcerative colitis patients, VDR expression was low and Claudin-2 was enhanced. Mechanistically, we identified the enhanced Claudin-2 promoter activity through the binding sites of NF-κB and STAT in inflamed VDR-/- cells.

CONCLUSIONS

Our studies have identified a new role for intestinal epithelial VDR in regulating barrier functions in the context of infection and inflammation.