ABSTRACT
Glutamate excitotoxicity may contribute to retinal ganglion cell (RGC) degeneration in glaucoma and other optic neuropathies, leading to irreversible blindness. Growing evidence has linked impaired mitochondrial quality control with RGCs degeneration, while parkin, an E3 ubiquitin ligase, has proved to be protective and promotes mitophagy in RGCs against excitotoxicity. The purpose of this study was to explore whether a small molecule S3 could modulate parkin-mediated mitophagy and has therapeutic potential for RGCs. The results showed that as an inhibitor of deubiquitinase USP30, S3 protected cultured RGCs and improved mitochondrial health against NMDA-induced excitotoxicity. Administration of S3 promoted the parkin expression and its downstream mitophagy-related proteins in RGCs. An upregulated ubiquitination level of Mfn2 and protein level of OPA1 were also observed in S3-treated RGCs, while parkin knockdown resulted in a major loss of the protective effect of S3 on RGCs under excitotoxicity. These findings demonstrated that S3 promoted RGC survival mainly through enhancing parkin-mediated mitophagy against excitotoxicity. The neuroprotective value of S3 in glaucoma and other optic neuropathies deserves further investigation.
Subject(s)
Mitophagy , Neuroprotective Agents , Retinal Ganglion Cells , Ubiquitin-Protein Ligases , Glaucoma/drug therapy , Glaucoma/metabolism , Glutamic Acid/metabolism , Humans , Mitochondrial Proteins/antagonists & inhibitors , Mitochondrial Proteins/metabolism , Mitophagy/drug effects , Mitophagy/physiology , Neuroprotective Agents/pharmacology , Neuroprotective Agents/therapeutic use , Neurotoxins/metabolism , Optic Nerve Diseases/drug therapy , Optic Nerve Diseases/metabolism , Retinal Ganglion Cells/drug effects , Retinal Ganglion Cells/metabolism , Thiolester Hydrolases/antagonists & inhibitors , Thiolester Hydrolases/metabolism , Ubiquitin-Protein Ligases/metabolismABSTRACT
Objective Renal cell carcinoma ( RCC) is a common renal malignancy, which is resistant to nearly all chemo-therapeutics and radiotherapy.Wnt signaling plays an important role in the tumorigenesis and cell proliferation and apoptosis of RCC. This study was to explore the inhibiting effect of 15-oxospiramilactone NC043, a new Wnt molecule inhibiter, on the xenograft growth of human renal carcinoma (ACHN) cells in nude mice. Methods ACHN cells (1 ×107) were suspended in 100μL PBS and injec-ted subcutaneously into the right side of the posterior flank of female BALB/c athymic nude mice to establish a xenograft model.The nude mice bearing ACHN cells were randomly divided into three groups, negative control, low-dose medication, and high-dose medica-tion, treated by daily intraperitoneal injection of 3%DMSO, NC043 at 45μg/kg, and NC043 at 90μg/kg, respectively, for 15 days. At 16 days, all the mice were killed, the body weight and tumor volume obtained, and the expressions of ki67, TCF4 and β-catenin determined by immunohistochemistry. Results NC043 significantly inhibited the growth of the xenograft tumor, with an inhibition rate of 36.4%in the 45 ug/kg group and 56.4% in 90 μg/kg group.The expressions of ki67, TCF4, andβ-catenin were markedly down-regu-lated in a dose-dependent manner ( P <0.01 ) . Conclusion NC043 can effectively suppress the growth of ACHN cells in the xeno-graft tumor and reduce the expression of Wnt-related proteins, andtherefore is a potential compound for the treatment of renal cell carcinoma.
ABSTRACT
Objective Wnt signaling plays an important role in the development and progression of renal cell carcinoma (RCC).This study aimed to evaluate the effects of the Wnt signaling inhibitor 15-oxospiramilactone on the proliferation , migration, cell apoptosis, and cycles of the human RCC cell line 786-0, and to investigate the possible mechanisms of this small molecule acting on RCC in ivtro. Methods We treated 786-0 cells with DMSO ( blank control group ) and 15-oxospiramilactone at the concentrations of1.25μmol/L (low 15 -OSL), 2.5μmol/L (medium 15-OSL), and 5μmol/L (high 15-OSL), respectively, for 72 hours.Then we observed the changes in the proliferation and migration of the 786-0 cells by MTT and scratch-wound assay and determined their apopto-sis and cycles by Annexin V-FITC/PI assay and flow cytometry . Results 15-oxospiramilactone significantly inhibited the growth of the 7860-cells, with the IC 50of 1.088 μmol/L at 72 hours, and decreased their migration distance (P<0.05).After 36 hours of treatment, the apoptosis rates of the 786-0 cells in the low, medium, and high 15-OSL groups were (12.17 ±0.56), (18.54 ± 1.07), and (50.74 ±1.28) %, respectively, significantly increased as compared with (7.85 ±0.42) %in the blank control group (P<0.05), and in an obviously concentration-dependent manner.15-oxospiramilactone remarkably reduced the number of cells in the G0/G1 phase and increased that in the G 2/M phase (P<0.05). Conclusion 15-oxospiramilactone can significantly inhibit the pro -liferation and migration and induce the apoptosis of 786-0cells in vitro.It may be a potential anti-RCC agent.
ABSTRACT
We have previously shown that the natural diterpenoid derivative S3 induced Bim upregulation and apoptosis in a Bax/Bak-independent manner. However, the exact molecular target(s) of S3 and the mechanism controlling Bim upregulation are still not clear. Here, we identify that S3 targets the selenoproteins TrxR1 and TrxR2 at the selenocysteine residue of the reactive center of the enzymes and inhibits their antioxidant activities. Consequently, cellular ROS is elevated, leading to the activation of FOXO3a, which contributes to Bim upregulation in Bax/Bak-deficient cells. Moreover, S3 retards tumor growth in subcutaneous xenograft tumors by inhibiting TrxR activity in vivo. Our studies delineate the signaling pathway controlling Bim upregulation, which results in Bax/Bak-independent apoptosis and provide evidence that the compounds can act as anticancer agents based on mammalian TrxRs inhibition.
