Mechanism of Resveratrol Improving Ischemia-Reperfusion Injury by Regulating Microglial Function Through microRNA-450b-5p/KEAP1/Nrf2 Pathway

Upregulation and functional roles of miR-450b in canine oral melanoma

Canine oral melanoma (COM) is a common and highly aggressive disease with the potential to model human melanomas. Dysregulated microRNAs represent an interesting line of research for COM because they are implicated in tumor progression. One example is miR-450b, which has been investigated for its molecular mechanisms and biological functions in multiple human cancers, but not human or canine melanoma. Here, we aimed to investigate miR-450b as a potential diagnostic biomarker of COM and its functional roles in metastatic and non-metastatic forms of the disease. We investigated the expression of miR-450b and its target mRNA genes in clinical (tumor tissue and plasma) samples and metastatic and primary-tumor cell lines. Knockdown and overexpression experiments were performed to determine the influence of miR-450b on cell proliferation, migration, colony formation, and apoptosis. miR-450b was significantly upregulated in COM and differentiated between metastatic and non-metastatic tumors, and its potential as a biomarker of metastatic and non-metastatic COM was further confirmed in ROC analysis. miR-450b knockdown promoted cell proliferation, migration, and clonogenicity and inhibited apoptosis, whereas its overexpression yielded the reverse pattern. miR-450b directly binds 3' UTR of PAX9 mRNA and modulates its function leading to BMP4 downregulation and MMP9 upregulation at the transcript level. Furthermore, we surmised that miR-450b activates the Wnt signaling pathway based on gene ontology and enrichment analyses. We concluded that miR-450b has the potential as a diagnostic biomarker and could be a target candidate for COM treatment.

Resveratrol protects against diabetic retinal ganglion cell damage by activating the Nrf2 signaling pathway

Objective

Oxidative stress-induced retinal neurodegenerative changes are among the pathological alterations observed in diabetic retinopathy. Resveratrol (RSV), a polyphenolic compound with diverse pharmacological effects, has shown preventive qualities in several neurodegenerative illnesses, including anti-inflammatory, anti-aging, and antioxidant benefits. However, its therapeutic efficacy in diabetic retinal neurodegeneration has not yet been thoroughly elucidated. Our study aimed to explore the protective mechanisms and therapeutic benefits of RSV on diabetic retinal neurodegeneration alterations.

Materials and methods

Using streptozotocin, we created a diabetic mouse model and conducted visual electrophysiological examinations on mice from the normal group, diabetic group, and diabetic group treated with RSV. Retinas were harvested for histological staining. Additionally, primary retinal ganglion cells cultured in high glucose conditions were used to assess malondialdehyde (MDA) levels and superoxide dismutase (SOD) levels upon siRNA-mediated nuclear factor erythroid 2-related factor 2 (Nrf2) interference. Protein levels of Nrf-2, heme oxygenase-1 (HO-1), and transcriptional levels of them were also measured.

Results

We demonstrated that RSV significantly improved the retinal morphology and function in the diabetic retinopathy model mice. The treated mice exhibited notable improvements in visual electrophysiology, with a significant reduction in retinal ganglion cell apoptosis. Following RSV treatment, the high glucose-cultured ganglion cells demonstrated a considerable rise in SOD levels and a substantial drop in MOD. Moreover, the protein expression of solute carrier family 7 member 11 (SLC7A11) and Nrf2 significantly increased. RT-PCR and Western blot results indicated a significant attenuation of RSV's therapeutic effects upon Nrf2 inhibition.

Conclusion

Our findings suggest that RSV may reduce oxidative stress levels in the retina and inhibit retinal ganglion cell apoptosis via reducing the Nrf2/HO-1 pathway, which lessens the harm that excessive glucose causes to the retina.

Nrf2 Regulates the Expression of CYP2D6 by Inhibiting the Activity of Krüppel-Like Factor 9 (KLF9)

AIMS

The aim of the present study is to gain insight into the biology of Parkinson's disease (PD) and cancer to drive translational advances enabling more effective prevention and/or potential treatments.

BACKGROUND

The expression of Cytochrome P450 2D6 (CYP2D6) is correlated with various diseases such as PD and cancer; therefore, exploring its regulatory mechanism at transcriptional levels is of interest. NF-E2-related factor 2 (Nrf2) has been known to be responsible for regulating phase II and phase III drug-metabolizing genes.

OBJECTIVES

The objectives of this study are to investigate the transcriptional regulation of CYP2D6 by Nrf2 and to analyze its role in PD and cancer.

METHODS

Nrf2 was transiently expressed in human hepatoma Hep3B cells, and the expression of CYP2D6 was examined by RT-qPCR. The promoter activity of CYP2D6 and the DNA binding of Nrf2 were examined by luciferase and ChIP assay, respectively. We then investigated the expression and correlation of Nrf2 and CYP2D6 in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets.

RESULTS

In the present study, we demonstrated that Nrf2 down-regulated CYP2D6 mRNA expression in hepatoma Hep3B cells. Mechanistically, Nrf2 binds to the antioxidant responsive element (ARE) in the proximity of krüppel- like factor 9 (KLF9)-binding site within the -550/+51 of CYP2D6 promoter. The inhibition and activation of Nrf2 enhanced and suppressed KLF9 effects on CYP2D6 expression, respectively. The expression levels of Nrf2 and CYP2D6 were upregulated and downregulated in the PD patient GEO datasets compared to the healthy control tissues, and Nrf2 was negatively correlated with CYP2D6. In liver cancer patients, decreased CYP2D6 levels were apparent and associated with a lower probability of survival.

CONCLUSION

Our work revealed the inhibitory role of Nrf2 in regulating CYP2D6 expression. Moreover, Nrf2- dependent regulation of CYP2D6 can be used as a prognostic factor and therapeutic strategy in PD and liver cancer.