Jeen-Woo Park

Oxidative stress has a key role in the pathogenesis of age-related macular degeneration (AMD). Cigarette smoking is known to the one of the main risk factors of AMD through oxidative stress-mediated endoplasmic reticulum (ER) stress and lipid accumulation in human retinal pigment epithelium (RPE) cells. A number of studies have investigated the benefits of antioxidants in the AMD. However, previous studies have not shown that efficacy of antioxidant in the treatment of AMD. Recent studies demonstrated that morin hydrate (MH) has antioxidant properties, anti-inflammatory, and antiapoptosis effects, however, the protective effects of MH against cigarette smoke extract (CSE)-induced AMD have not been studied in detail. We tested the potential effect of MH against the CSE-induced lipid accumulation in RPE cells and mice RPE layer. Herein, we observed that expose of RPE cells to CSE reduced cell viability, increased the lipid accumulation, ER stress and oxidative stress. Concomitantly, CSE treatment to mice induced AMD associated histopathological changes, lipid accumulation, ER stress and oxidative stress in RPE layer. MH significantly attenuated cytotoxicity, lipid accumulation, ER stress and oxidative stress via activated AMPK-Nrf2 signaling pathway in RPE cells and mice RPE layer. In addition, AMPK inhibition reversed MH-induced RPE cell protection against CSE. Thus, we conclude that MH protects RPE cells from CSE through reduced oxidative stress, ER stress, and lipid accumulation via activated AMPK-Nrf2-HO-1 signaling pathway. These findings suggest that MH treatment may be exploited in effective strategy against CSE-induced AMD.

Melanoma is the most aggressive skin cancer due to a high propensity for metastasis, with a 10-year survival rate of less than 10%. The devastating clinical outcome and lack of effective preventative therapeutics for metastatic melanoma necessitate the development of new therapeutic strategies targeted to inhibit the regulatory circuits underlying the progression and metastasis of melanoma. Melanoma metastasis requires migration and invasion of the malignant tumor cells driven by proteolytic remodeling of the extracellular matrix (ECM) executed by matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9. Inhibiting components of these circuits defines new therapeutic opportunities for melanoma with metastatic malignancy. Oxalomalate (OMA) is a competitive inhibitor of NADP⁺-dependent isocitrate dehydrogenase (IDH), which plays an important role in cellular signaling pathways regulated by reactive oxygen species (ROS). In this study, we investigated the therapeutic role of OMA in metastatic melanoma and the associated underlying mechanism of action. We report that OMA-mediated inhibition of IDH enzymes suppresses metastatic melanoma through inhibition of invasive cell migration based on MMP-9-mediated proteolytic remodeling of the ECM. In particular, our study provides the mechanistic foundation that OMA reduces the expression and secretion of MMP-9 through LKB1-mediated PEA3 degradation via the ROS-dependent ATM-Chk2-p53 signaling axis, resulting from inhibition of IDH enzymes. These results provide evidence that OMA targeting of the stress response to ROS by IDH inhibition is a promising therapy for the treatment of metastatic melanoma.

Lysine-specific histone demethylase 5C (KDM5C) belongs to the jumonji family of demethylases and is specific for the di- and tri-demethylation of lysine 4 residues on histone 3 (H3K4 me2/3). KDM5C is expressed in the brain and skeletal muscles of humans and is associated with various biologically significant processes. KDM5C is known to be associated with X-linked mental retardation and is also involved in the development of cancer. However, the developmental significance of KDM5C has not been explored yet. In the present study, we investigated the physiological roles of KDM5C during Xenopus laevis embryonic development. Loss-of-function analysis using kdm5c antisense morpholino oligonucleotides indicated that kdm5c knockdown led to small-sized heads, reduced cartilage size, and malformed eyes (i.e., small-sized and deformed eyes). Molecular analyses of KDM5C functional roles using whole-mount in situ hybridization, β-galactosidase staining, and reverse transcription-polymerase chain reaction revealed that loss of kdm5c resulted in reduced expression levels of neural crest specifiers and genes involved in eye development. Furthermore, transcriptome analysis indicated the significance of KDM5C in morphogenesis and organogenesis. Our findings indicated that KDM5C is associated with embryonic development and provided additional information regarding the complex and dynamic gene network that regulates neural crest formation and eye development. This study emphasizes the functional significance of KDM5C in Xenopus embryogenesis; however, further analysis is needed to explore the interactions of KDM5C with specific developmental genes.