Study Design.
In vitro studies of the role of 17β-estradiol (E2) and its possible targets in intervertebral disc degeneration (IDD).
Objective.
To define the regulatory role of E2 in IDD and the potential mechanisms.
Summary of Background Data.
IDD has intricate etiology that is influenced by multiple risk factors. However, the underlying molecular mechanisms of occurrence and progression of IDD are not well elucidated. The degradation of extracellular matrix (ECM) has been extensively observed in IDD. E2 was found to inhibit ECM degradation in human nuleus pulposus cells (HNPCs), but the molecular mechanism remained to be determined.
Methods.
Western blot and qPCR was performed to quantify the expression of target proteins in HNPCs. Luciferase reporter gene assay was applied to detect the effects of E2 and forkhead box O-3 (FOXO3) on matrix metalloproteinases (MMP)-3 promoter activity. Chromatin immunoprecipitation assay analyzed the binding of FOXO3 to MMP-3 and the effect of E2 on this process.
Results.
We identified the upregulation of collagen II and aggrecan by E2 independent of time and concentration. And E2 downregulated MMP-3 expression in human nucleus pulposus cells. The phosphorylation of FOXO3 led to the reduction of MMP-3 promoter activity. Furthermore, 17β-estradiol-induced the activation of PI3K/Akt pathway is required for FOXO3 phosphorylated.
Conclusion.
E2 prevents the degradation of ECM by upregulating collagen II and aggrecan expression via reducing MMP-3 expression in HNPCs, and PI3K/Akt/FOXO3 pathway is dispensable for MMP-3 downregulated. Therefore, E2 protects against IDD by preventing ECM degradation.
Level of Evidence: 3
Inonotus obliquus (Fr.) Pilat (Hymenochaetaceae) has been widely used as a folk medicine to treat various cancers in Russia, Poland and most of Baltic countries for literally more than four centuries. However, in spite of its therapeutic significance for cancers, this fungus has not been studied systematically for the mechanisms of antitumor activity. In this study, we report the effects of aqueous extracts of I. obliquus (AEI) on inducing apoptosis of Sarcoma 180. AEI prepared from the sclerotium of I. obliquus was either administered to Sarcoma 180-bearing mice or supplemented into the culture of Sarcoma 180 cells. Oral administration of AEI significantly inhibited Sarcoma 180-induced reduction of splenic lymphocytes and proliferation potentials and elicited over-expression of bax gene in Sarcoma 180 cells, leading to the regression of Sarcoma 180 in mice. Supplementation of AEI into the culture of Sarcoma 180 cells resulted in a significant increase in the number of cells in G0-G1 phase and triggered remarkable increment in programmed death (apoptosis) of Sarcoma 180 cells. In addition, AEI showed stimulatory effect on TNF-α release by mice peritoneal macrophages. These results indicated that the antitumor activity of AEI was mediated by protecting splenic lymphocytes from tumor-induced apoptosis and by triggering apoptosis of tumor cells.
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