Effects of Lobeglitazone, a New Thiazolidinedione, on Osteoblastogenesis and Bone Mineral Density in Mice.

BACKGROUND: Bone strength is impaired in patients with type 2 diabetes mellitus despite an increase in bone mineral density (BMD). Thiazolidinedione (TZD), a peroxisome proliferator activated receptor γ agonist, promotes adipogenesis, and suppresses osteoblastogenesis. Therefore, its use is associated with an increased risk of fracture. The aim of this study was to examine the in vitro and in vivo effects of lobeglitazone, a new TZD, on bone. METHODS: MC3T3E1 and C3H10T1/2 cells were cultured in osteogenic medium and exposed to lobeglitazone (0.1 or 1 µM), rosiglitazone (0.4 µM), or pioglitazone (1 µM) for 10 to 14 days. Alkaline phosphatase (ALP) activity, Alizarin red staining, and osteoblast marker gene expression were analyzed. For in vivo experiments, 6-month-old C57BL/6 mice were treated with vehicle, one of two doses of lobeglitazone, rosiglitazone, or pioglitazone. BMD was assessed using a PIXImus2 instrument at the baseline and after 12 weeks of treatment. RESULTS: As expected, in vitro experiments showed that ALP activity was suppressed and the mRNA expression of osteoblast marker genes RUNX2 (runt-related transcription factor 2) and osteocalcin was significantly attenuated after rosiglitazone treatment. By contrast, lobeglitazone at either dose did not inhibit these variables. Rosiglitazone-treated mice showed significantly accelerated bone loss for the whole bone and femur, but BMD did not differ significantly between the lobeglitazone-treated and vehicle-treated mice. CONCLUSION: These findings suggest that lobeglitazone has no detrimental effects on osteoblast biology and might not induce side effects in the skeletal system.

Wnt/ß-catenin signaling is a key downstream mediator of MET signaling in glioblastoma stem cells.

BACKGROUND: Glioblastoma (GBM) is the most lethal and common type of primary brain tumor. Recent evidence suggests that a subpopulation of GBM cells (glioblastoma stem cells [GSCs]) is critical for tumor progression, invasion, and therapeutic resistance. We and others have demonstrated that MET, a receptor tyrosine kinase, positively regulates the stemness phenotype and radioresistance of GSCs. Here, we interrogated the downstream effector pathways of MET signaling in GSCs. METHODS: We have established a series of GSCs and xenograft tumors derived from freshly dissociated specimens from patients with GBM and characterized a subpopulation enriched with MET activation (MET(high/+)). Through global expression profiling and subsequent pathways analysis, we identified signaling pathways that are enriched in MET(high/+) populations, one of which is Wnt/ß-catenin signaling pathway. To determine molecular interaction and the biological consequences of MET and Wnt/ß-catenin signaling, we used pharmacological and shRNA-mediated genetic inhibition and performed various molecular and cellular analyses, including flow cytometry, immunohistochemistry, and clonogenicity assays. RESULTS: We found that Wnt/ß-catenin signaling is highly active in MET(high/+) cells, compared with bulk tumor cells. We also showed that Wnt/ß-catenin signaling activities in GBM are directly modulated by the addition of ligand-mediated MET activation or MET inhibition. Furthermore, the ectopic expression of active-ß-catenin (S37A and S45Y) rescued the phenotypic effects caused by MET inhibition. CONCLUSION: These data suggest that Wnt/ß-catenin signaling is a key downstream effector of MET signaling and contributes to the maintenance of GSC and GBM malignancy.

Effects of amniotic membrane suspension in human corneal wound healing in vitro.

PURPOSE: To investigate the biochemical mechanism of amniotic membrane (AM) suspension on corneal wound healing, particularly on epithelial proliferation and migration. METHODS: Human corneal epithelial cells (HCECs) were cultured in media with different concentrations of AM suspension (5% and 30%), Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (negative control), and serum containing Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (positive control). In an effort to evaluate the migratory potential of AM, migration assays were conducted via the manual scraping of HCECs and immunocytochemical staining of cell adhesion molecules (E-cadherin). The relative expression of matrix metallopeptidase 9 (MMP9) and adhesion molecules (E-cadherin, fibronectin) was determined via reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. The proliferative potential of AM was evaluated via a proliferation assay using 5-Bromo-2-deoxyuridine (BrdU) incorporation and western blot analysis for proliferating cell nuclear antigen (PCNA). In addition, enzyme-linked immunosorbent assay (ELISA) was used to measure the protein concentrations of mitogenic growth factors (epidermal growth factor [EGF],keratinocyte growth factor [KGF], hepatocyte growth factor [HGF], and basic fibroblast growth factor [bFGF]) in AM suspensions. RESULTS: Migration assay rates were enhanced as AM concentrations increased, with statistically significant changes seen in 30% AM-treated and positive control cells, compared to negative control cells (p<0.05). RT-PCRs revealed that the expression of the MMP9 gene was upregulated by AM, and the expressions of E-cadherin and fibronectin genes were downregulated by AM. Western blot analysis demonstrated significantly higher MMP9 expression in AM-treated groups, versus significantly lower levels of E-cadherin and fibronectin expression in AM-treated groups. Immunocytochemistry showed large quantities of E-cadherin near the wound edges after 24 h of injury in the AM-treated groups. The proliferation assay showed that the BrdU positive cell counts/total cell counts (labeling index) were augmented by AM to a statistically significant degree (p<0.05 in the 30% AM and positive control groups). Western blot analysis showed that the expression cell cycle-associated protein, PCNA, increased gradually as a result of AM treatment. ELISA showed that our AM suspension contained 4 growth factors (HGF, EGF, KGF, and FGF). The amount of HGF was especially large, followed by that of EGF. CONCLUSIONS: These results demonstrate that the suspension form of AM maintains its beneficial effect on corneal epithelial wound healing in vitro, and that AM suspension leads to significant increases in corneal epithelial migration and proliferation with increasing AM concentrations.