Gamma-Secretase Inhibitor, DAPT, Prevents the Development of Retinopathy of Prematurity in a Rat Model by Regulating the Delta-Like Ligand 4/Notch Homolog-1 (DLL4/Notch-1) Pathway

Notch pathway inhibitor DAPT accelerates in vitro proliferation and adipogenesis in infantile hemangioma stem cells

The Notch signaling pathway is crucial in both adipogenesis and tumor development. It serves a vital role in the development and stability of blood vessels and may be involved in the proliferative phase of infantile hemangiomas, which express various related receptors. Therefore, it was hypothesized that the Notch signaling pathway inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor, might help accelerate the regression of infantile hemangiomas. The present in vitro study evaluated whether inhibition of the Notch signaling pathway using DAPT could alter adipogenesis in hemangioma stem cells (HemSCs) derived from infantile hemangioma (IH) specimens. A total of 20 infants (age, ≤6 months) with hemangiomas who had not yet received any treatment were selected, and their discarded hemangioma tissues were obtained. HemSCs were isolated from the fresh, sterile IH specimens and treated with DAPT. Reverse transcription-quantitative PCR and western blotting were used to demonstrate the inhibition of the Notch signaling pathway by DAPT. A proliferation assay (Cell Counting Kit-8), oil red O staining, flow cytometry and a transwell assay were used to detect proliferation, adipogenesis, apoptosis and migration of HemSCs. Treatment with DAPT upregulated the expression levels of CCAAT/enhancer-binding protein (C/EBP) α, C/EBPβ, peroxisome proliferator-activated receptor-γ, adiponectin and insulin-like growth factor 1, and promoted the proliferation, apoptosis, migration and lipid accumulation in HemSCs in vitro. Targeting the Notch signaling pathway using DAPT may potentially accelerate the regression of infantile hemangiomas.

Long non-coding RNA UCA1 promotes malignant phenotypes of renal cancer cells by modulating the miR-182-5p/DLL4 axis as a ceRNA

Background

Accumulating literatures have indicated that long non-coding RNAs (lncRNAs) are potential biomarkers that play key roles in tumor development and progression. Urothelial cancer associated 1 (UCA1) is a novel lncRNA that acts as a potential biomarker and is involved in the development of cancers. However, the molecular mechanism of UCA1 in renal cancer is still needed to further explore.

Methods

The relative expression level of UCA1 was determined by Real-Time qPCR in a total of 88 patients with urothelial renal cancer and in different renal cancer cell lines. Loss-of-function experiments were performed to investigate the biological roles of UCA1 and miR-182-5p on renal cancer cell proliferation, migration, apoptosis and tumorigenicity. Comprehensive transcriptional analysis, dual-luciferase reporter assay and western blot etc. were performed to explore the molecular mechanisms underlying the functions of UCA1.

Results

In this study, we found that UCA1 was significantly up-regulated in renal cancer. Moreover, increased UCA1 expression was positively correlated with differentiation and advanced TNM stage. Further experiments demonstrated that knockdown of UCA1 inhibited malignant phenotypes and Notch signal path of renal cancer cells, and miR-182-5p was reverse function as UCA1. UCA1 functioned as a miRNA sponge to positively regulate the expression of Delta-like ligand 4(DLL4) through sponging miR-182-5p and subsequently promoted malignant phenotypes of renal cancer cells, thus UCA1 playing an oncogenic role and miR-182-5p as an antioncogenic one in renal cancer pathogenesis.

Conclusion

UCA1-miR-182-5p-DLL4 axis is involved in proliferation and progression of renal cancer. Thus, this study demonstrated that UCA1 plays a critical regulatory role in renal cancer cell and UCA1 may serve as a potential diagnostic biomarker and therapeutic target of renal cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-020-1132-x.

DAPT reverses the Th17/Treg imbalance in experimental autoimmune uveitis in vitro via inhibiting Notch signaling pathway

Uveitis is the most common cause in inflammatory eye diseases that can lead to visual impairment even blindness worldwide. T helper (Th) 17 and regulatory T (Treg) cells are critical mediators for immune response. Notch signaling can regulate the cell differentiation, playing a role in the pathogenesis of the diseases. In this study, we measured the expression levels of Notch1, DLL4, IL-10, IL-17, RORγt and Foxp3 in T cells from lymph node, spleen and eye tissues in experimental autoimmune uveitis (EAU) rats in vitro, determined the ratios of CD4⁺/CD8⁺ and Th17/Treg. Moreover, we also investigated the effect of Notch signaling inhibitor N-(N-(3,5-Difluorophenacetyl-L-alanyl))-S-phenylglycine t-Butyl Ester (DAPT) on Notch1, DLL4 expression and on Th17, Treg cell differentiation. The results indicated that the pathogenesis of uveitis accompanied by the elevated expression of Notch1, DLL4, IL-10, IL-17, RORγt, and Foxp3 as well as the imbalanced CD4⁺/CD8⁺ and Th17/Treg ratios. By contrast, inhibition of Notch signaling by DAPT can efficiently decrease Th17 cell response, downregulate the expression of Notch1, DLL4, IL-17 and the transcription of RORγt, reduce Th17 levels and restore the CD4⁺/CD8⁺, Th17/Treg balance. Moreover, DAPT can also inhibit Th17 cell differentiation in healthy rats, though the inhibitory capacity of Th17, Treg differentiation is less than that in EAU rats. Overall, Notch signaling activation can lead to the disturbed Th17/Treg balance in uveitis, whereas inhibition of Notch signaling can ameliorate the inflammatory response and may be a potential immunoregulatory strategy in patients with uveitis.