Magnolol regulates miR-200c-3p to inhibit epithelial-mesenchymal transition and retinoblastoma progression by modulating the ZEB1/E-cadherin axis in vitro and in vivo.

BACKGROUND: Retinoblastoma, the most common pediatric intraocular malignancy, can develop during embryogenesis, with most children being diagnosed at 3-4 years of age. Multimodal therapies are typically associated with high levels of cytotoxicity and side effects. Therefore, the development of novel treatments with minimal side effects is crucial. Magnolol has a significant anti-tumor effect on various cancers. However, its antitumor effect on retinoblastoma remains unclear. PURPOSE: The study aimed to determine the effects of magnolol on the regulation of EMT, migration, invasion, and cancer progression in retinoblastoma and the modulation of miR-200c-3p expression and the Wnt/ zinc finger E-box binding homeobox 1 (ZEB1)/E-cadherin axis in vivo and in vitro. METHODS: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay was used to evaluate magnolol-induced cell toxicity in the Y79 retinoblastoma cell line. Flow cytometry and immunostaining assays were performed to investigate the magnolol-regulated mitochondrial membrane potential and the intracellular and mitochondrial reactive oxygen species levels in Y79 retinoblastoma cells. Orthotopic and subcutaneous xenograft experiments were performed in eight-week-old male null mice to study retinoblastoma progression and metastasis. In situ hybridization and quantitative reverse transcription polymerase chain reaction (RT-qPCR) assays were performed to evaluate the level of the anti-cancer miRNA miR-200c-3p. The mRNA and protein levels of E-cadherin, ß-catenin, α-smooth muscle actin (α-SMA), fibronectin-1, and ZEB1 were analyzed using RT-qPCR, immunoblot, immunocytochemistry, and immunohistochemistry assays in vitro and in vivo. RESULTS: Magnolol increased E-cadherin levels and reduced the activation of the EMT signaling pathway, EMT, tumor growth, metastasis, and cancer progression in the Y79 retinoblastoma cell line as well as in the orthotopic and subcutaneous xenograft animal models. Furthermore, magnolol increased the expression of miR-200c-3p. Our results demonstrate that miRNA-200c-3p inhibits EMT progression through the Wnt16/ß-catenin/ZEB1/E-cadherin axis, and the ZEB1 silencing response shows that miR-200c-3p regulates ZEB1-mediated EMT in retinoblastoma. CONCLUSION: Magnolol has an antitumor effect by increasing E-cadherin and miRNA-200c-3p expression to regulate ZEB1-mediated EMT and cancer progression in retinoblastoma. The anti-tumor effect of magnolol by increasing E-cadherin and miRNA-200c-3p expression to regulate ZEB1-mediated EMT and cancer progression in retinoblastoma has been elucidated for the first time.

Bace1-dependent amyloid processing regulates hypothalamic leptin sensitivity in obese mice.

Obesity places an enormous medical and economic burden on society. The principal driver appears to be central leptin resistance with hyperleptinemia. Accordingly, a compound that reverses or prevents leptin resistance should promote weight normalisation and improve glucose homeostasis. The protease Bace1 drives beta amyloid (Aß) production with obesity elevating hypothalamic Bace1 activity and Aß1-42 production. Pharmacological inhibition of Bace1 reduces body weight, improves glucose homeostasis and lowers plasma leptin in diet-induced obese (DIO) mice. These actions are not apparent in ob/ob or db/db mice, indicating the requirement for functional leptin signalling. Decreasing Bace1 activity normalises hypothalamic inflammation, lowers PTP1B and SOCS3 and restores hypothalamic leptin sensitivity and pSTAT3 response in obese mice, but does not affect leptin sensitivity in lean mice. Raising central Aß1-42 levels in the early stage of DIO increases hypothalamic basal pSTAT3 and reduces the amplitude of the leptin pSTAT3 signal without increased inflammation. Thus, elevated Aß1-42 promotes hypothalamic leptin resistance, which is associated with diminished whole-body sensitivity to exogenous leptin and exacerbated body weight gain in high fat fed mice. These results indicate that Bace1 inhibitors, currently in clinical trials for Alzheimer's disease, may be useful agents for the treatment of obesity and associated diabetes.