NOTCH pathway activation in infantile hemangiomas

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.

Knockdown of lncRNA MEG8 inhibits cell proliferation and invasion, but promotes cell apoptosis in hemangioma, via miR‑203‑induced mediation of the Notch signaling pathway

As a member of the long non‑coding (lnc)RNA family, lncRNA maternally expressed 8, small nucleolar RNA host gene (MEG8), has been reported to serve an oncogenic role in several types of malignancies, including hepatocellular carcinoma, non‑small cell lung cancer and pancreatic cancer. The current study aimed to investigate the effect of the knockdown of MEG8 on human hemangioma endothelial cell (HemEC) proliferation, apoptosis and invasion, in addition to determining the underlying molecular mechanism. The knockdown of lncRNA MEG8 was achieved by transfecting lncRNA MEG8 small interfering (si)RNA into HemECs, while the combined knockdown of lncRNA MEG8 knockdown and microRNA (miR)‑203 was established by co‑transfecting lncRNA MEG8 siRNA and a miR‑203 inhibitor into HemECs. The cell proliferation, apoptosis and invasion and the expression levels of miR‑34a, miR‑200b, miR‑200b and Notch signaling pathway‑related factors were detected via CCK‑8 Kit, flow cytometry, Transwell, reverse transcription‑quantitative PCR and western blot assay, respectively. The knockdown of lncRNA MEG8 significantly inhibited proliferation (P<0.05) and invasion (P<0.05), but promoted apoptosis (P<0.01) in HemECs. Furthermore, lncRNA MEG8 knockdown upregulated miR‑203 (P<0.01) expression, but did not alter miR‑34a or miR‑200b expression (both P>0.05). Subsequent experiments revealed that miR‑203 silencing exerted no significant effect on the expression levels of lncRNA MEG8 (P>0.05) in HemECs. In addition, miR‑203 silencing increased cell proliferation (P<0.05) and invasion (P<0.01), but suppressed apoptosis (P<0.05). miR‑203 silencing also reversed the effect of lncRNA MEG8 knockdown on the proliferation (P<0.05), apoptosis (P<0.001) and invasion (P<0.01) of HemECs. Moreover, lncRNA MEG8 knockdown downregulated jagged canonical notch ligand 1 (JAG1; P<0.05) and Notch1 (P<0.05) expression levels, while miR‑203 silencing upregulated JAG1 (P<0.01) and Notch1 (P<0.01) expression levels and reversed the effects of lncRNA MEG8 knockdown on JAG1 (P<0.01) and Notch1 (P<0.01) expression in HemECs. In conclusion, the findings of the present study suggested that lncRNA MEG8 knockdown may inhibit cell proliferation and invasion, but promote cell apoptosis in hemangioma via miR‑203‑induced mediation of the Notch signaling pathway.

Propranolol Inhibits the Proliferation of Human Glioblastoma Cell Lines through Notch1 and Hes1 Signaling System

Objective

The anti-tumor effect of the beta-adrenergic receptor antagonist propranolol in breast cancer is well known; however, its activity in glioblastoma is not well-evaluated. The Notch-Hes pathway is known to regulate cell differentiation, proliferation, and apoptosis. We investigated the effect of propranolol to human glioblastoma cell lines, and the role of Notch and Hes signaling in this process.

Methods

We performed immunohistochemical staining on 31 surgically resected primary human glioblastoma tissues. We also used glioblastoma cell lines of U87-MG, LN229, and neuroblastoma cell line of SH-SY5Y in this study. The effect of propranolol and isoproterenol on cell proliferation was evaluated using the MTT assay (absorbance 570 nm). The impact of propranolol on gene expression (Notch and Hes) was evaluated using real-time polymerase chain reaction (RT-PCR, whereas protein levels of Notch1 and Hes1 were measured using Western blotting (WB), simultaneously. Small interfering RNA (siRNA) was used to suppress the Notch gene to investigate its role in the proliferation of glioblastoma.

Results

Propranolol and isoproterenol caused a dose-dependent decrease in cell proliferation (MTT assay). RT-PCR showed an increase in Notch1 and Hes1 expression by propranolol, whereas WB demonstrated increase in Notch1 protein, but a decrease in Hes1 by propranolol. The proliferation of U87-MG and LN229 was not significantly suppressed after transfection with Notch siRNA.

Conclusion

These results demonstrated that propranolol suppressed the proliferation of glioblastoma cell lines and neuroblastoma cell line, and Hes1 was more closely involved than Notch1 was in glioblastoma proliferation.

Silencing long non-coding RNA MEG8 inhibits the proliferation and induces the ferroptosis of hemangioma endothelial cells by regulating miR-497-5p/NOTCH2 axis

Even though long non-coding RNA (lncRNA) MEG8 plays vital roles in carcinogenesis of malignances, its roles and mechanisms in hemangioma remain unknown. Therefore, we evaluate the oncogenic roles of MEG8 in hemangioma. Small interfering RNA (siRNA)-mediated depletion of MEG8 inhibited the proliferation and increased MDA level in human hemangioma endothelial cells (HemECs). The inhibitors of ferroptosis (ferrostatin-1 and liproxstatin-1) abolished the MEG8 silence induced cell viability loss. Knockdown of MEG8 increased the miR-497-5p expression and reduced the mRNA and protein levels of NOTCH2. Using a dual-luciferase assay, we confirmed the binding between MEG8 and miR-497-5p, and between the miR-497-5p and 3'UTR of NOTCH2. We further found that silencing MEG8 significantly decreased the expressions of SLC7A11 and GPX4 both in mRNA and protein level and had no effect on the level of AIFM2. Importantly, blocking miR-497-5p abrogated the effects of MEG8 loss on cell viability, MDA level and expression levels of NOTCH2, SLC7A11 and GPX4 in HemECs. Taken together, our results suggested that knockdown of long non-coding RNA MEG8 inhibited the proliferation and induced the ferroptosis of hemangioma endothelial cells by regulating miR-497-5p/NOTCH2 axis.