LGR5 enhances the osteoblastic differentiation of MC3T3-E1 cells through the Wnt/ß-catenin pathway.

Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) is a Wnt-associated gene that contributes to cell proliferation and self-renewal in various organs. LGR5 is expressed in Ewing sarcoma, and LGR5-overexpressing mesenchymal stem cells promote fracture healing. However, the effects of LGR5 on osteoblastic differentiation remain unclear. The aim of the present study was to explore the function of LGR5 in osteoblastic differentiation. LGR5 was overexpressed or knocked down in the MC3T3-E1 pre-osteoblastic cell line via lentiviral transfection and its function in osteoblastic differentiation was investigated. The mRNA expression levels of the osteoblast differentiation markers alkaline phosphatase (ALP), osteocalcin and collagen type I a1 were determined, and ALP and Alizarin red staining were performed. In addition, the effects of LGR5 modulation on ß-catenin and the expression of target genes in the Wnt pathway were investigated. The results revealed that the overexpression of LGR5 promoted osteoblastic differentiation. This was associated with enhancement of the stability of ß-catenin and its levels in the cell nucleus, which enabled it to activate Wnt signaling. By contrast, the inhibition of LGR5 decreased the osteogenic capacity of MC3T3-E1 cells. These results indicate that LGR5 is a positive regulator of osteoblastic differentiation, whose effects are mediated through the Wnt/ß-catenin signaling pathway. This suggests suggesting that the regulation of LGR5/Wnt/ß-catenin signaling has potential as a therapy for osteoporosis.

Epigallocatechin Gallate Preferentially Inhibits O6-Methylguanine DNA-Methyltransferase Expression in Glioblastoma Cells Rather than in Nontumor Glial Cells.

OBJECTIVE: O6-methylguanine (O6-meG) DNA-methyltransferase (MGMT) is a main regulator of temozolomide (TMZ) resistance in glioblastomas. Some MGMT inhibitors have been studied in clinical trials but with very little success, because their inhibiting effects were not tumor-selective, and often cause severe toxicity in normal tissues in the presence of TMZ. The goal of this study is to explore whether Epigallocatechin gallate (EGCG), a natural small molecule, could preferentially modulate MGMT in glioblastoma cells. METHODS: Two MGMT-positive glioblastoma cell lines (GBM-XD and T98G) and one nontumor glial cell culture (GliaX) were included in this study. The MGMT promoter methylation status, mRNA abundance, and protein levels were determined before and after EGCG treatment. The mechanisms were characterized. RESULTS: EGCG substantially suppressed mRNA and protein expression of MGMT, and reversed TMZ resistance in MGMT-positive GBM-XD and T98G cells via the WNT/ß-catenin pathway. EGCG prevented ß-catenin translocation into the nucleus and might directly inhibit the transcription factors TCF1 and LEF1. Meanwhile, EGCG enhanced the MGMT expression in the nontumor glial cells, through inhibition of the DNMT1 and demethylation of MGMT promoter. CONCLUSIONS: EGCG preferentially inhibits MGMT and enhances TMZ cytotoxicity in glioblastoma cells rather than in nontumor glial cells.

FM19G11 inhibits O6 -methylguanine DNA-methyltransferase expression under both hypoxic and normoxic conditions.

FM19G11 is a small molecular agent that inhibits hypoxia-inducible factor-1-alpha (HIF-1α) and other signaling pathways. In this study, we characterized the modulating effects of FM19G11 on O6 -methylguanine DNA-methyltransferase (MGMT), the main regulator of temozolomide (TMZ) resistance in glioblastomas. This study included 2 MGMT-positive cell lines (GBM-XD and T98G). MGMT promoter methylation status, mRNA abundance, and protein levels were determined before and after FM19G11 treatment, and the roles of various signaling pathways were characterized. Under hypoxic conditions, MGMT mRNA and protein levels were significantly downregulated by FM19G11 via the HIF-1α pathway in both GBM-XD and T98G cells. In normoxic culture, T98G cells were strongly positive for MGMT, and MGMT expression was substantially downregulated by FM19G11 via the NF-κB pathway. In addition, TMZ resistance was reversed by treatment with FM19G11. Meanwhile, FM19G11 has no cytotoxicity at its effective dose. FM19G11 could potentially be used to counteract TMZ resistance in MGMT-positive glioblastomas.

[Adsorption Characteristics of Norfloxacin by Biochars Derived from Reed Straw and Municipal Sludge].

Two types of biochars were prepared by pyrolyzing reed straw and municipal sludge at the temperature of 500 degrees C. The structure and properties of biochars were characterized by BET, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and fourier transform infrared spectroscopy ( FTIR ). The effects of pH value, adsorption time, temperature and initial concentration of norfloxacin (NOR) on the adsorption behaviors were determined by single factor experiments, which were used to preliminarily discuss adsorption mechanism. The results showed that the adsorption of NOR onto biochars derived from reed straw and municipal sludge could reach 70% and 60% of the total adsorption within 12 h, respectively; the maximum adsorption capacities of the two biochars were 2.13 mg x g(-1) (biochar derived from reed straw) and 2.09 mg x g(-1) (biochar derived from municipal sludge). The quantities of both absorptions increased with the decreasing solution pH. The two adsorption kinetics of NOR onto biochars followed the pseudo second order kinetic equations, and adsorption isotherms fitted well with the Langmuir equations. Adsorption thermodynamics parameters such as Gibbs free energy (AG), enthalpy (AH) and entropy (AS) indicated that the two adsorptions were endothermic reactions. Infrared spectroscopy analysis indicated that oxygen-containing functional groups on biochars provided NOR molecules with adsorptive sites, which facilitated the formation of hydrogen bonds between NOR and the biochars.