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Aim: The effect of coumarin derivatives on melanogenesis was investigated in B16 murine melanoma cells. Methods: Melanin content and tyrosinase activity were analyzed spectrophotometrically. The expression of tyrosinase, tyrosinaserelated protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2) were measured either by reverse transcription-polymerase chain reaction (RT-PCR) or Western blot. Results: Among the coumarin derivatives studied, scoparone (6,7-dimethoxycoumarin) was the most potent; the 6-or 7-methoxy group was found to be essential for the stimulation of melanogenesis. The melanin content was greatly increased by scoparone in a dose-dependent manner; there was no cytotoxicity at the effective concentrations. Scoparone increased enzyme activity as well as protein and mRNA expression of tyrosinase. In addition, mRNA of TRP-1 and TRP-2 were also increased after treatment with scoparone. H-89, an inhibitor of protein kinase A (PKA), completely inhibited the scoparone-induced increase of melanogenesis and the tyrosinase protein. Conclusion: These results suggest that scoparone-induced stimulation of melanogenesis is likely to occur at the transcriptional level of melanogenesis-related enzymes through PKA signaling.

The ageing of an inevitable life function is an unavoidable regressive physical process. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor family. PPARgamma plays an important role in regulating several metabolic pathways. Recently, PPARgamma has been implicated in inflammatory responses and age-related diseases. The aim of this study was to determine the anti-inflammatory reaction of PPARgamma in an induced ageing progress. The late passage of human diploid fibroblasts (HDF), an in vitro ageing model, reveals the biological index materials of ageing. Aged cells showed decreased PPARgamma expression and elevated levels of intracellular adhesion molecule-1 (ICAM-1), an inflammatory molecule. To induce the aged cell phenotype, the middle stage of HDF cells (PD31) were induced stress induced premature senescence (SIPS) with 200 microM H(2)O(2) for 2 h. SIPS-HDF cells showed high levels of ICAM-1, extracellular signal regulated kinase (ERK1/2) activity and matrix metallomatrix protease (MMP-2, -9) activity, and low levels of PPARgamma expression. A reconstitution of SIPS HDF cells with Ad/PPARgamma resulted in the downregulation of ICAM-1, ERK1/2, MMP-2 and -9, and normalized growth of SIPS-HDF cells. Moreover, PPARgamma in aged HDF cells reduced pro-inflammatory molecules and eliminated the formation of reactive oxygen species (ROS) through the ERK1/2 pathway. These results strongly suggest that PPARgamma plays a key role in age-related inflammation and may have clinical applications as a molecular target in the treatment of age-related inflammation.

Diallyl disulfide (DADS) induced apoptosis through the caspase-3 dependent pathway in leukemia cells was earlier reported from this laboratory. In this study, we investigated the involvement of Ca 2+ in DADS-induced apoptotic cell death of HCT-15, human colon cancer cell line.

Titanium is biocompatible with bodily tissues. However, the formation of ROS on the titanium surfaces might have negative response of the activity of the surroundings cells. Terrein was isolated from Penicullium sp. 20135 and found to reduce the effects of LPS-induced inflammation. This study examined the role of Terrein on the biocompatibility of titanium to determine if it can help improve osseointegration. MC-3T3 E1 cells were grown on titanium surfaces. The biocompatibility of Terrein was examined by adding it directly to the culture media at the indicated concentration. The cells on the titanium surface produced excessive ROS and decreased the activity of Cu/Zn SOD and Mn SOD. Moreover, the cells had higher activity towards oxidative stress molecules, such as MAPK, FAK and iNOS expression. In addition, MC-3T3 E1 osteoblast-like cells promoted osteoclast differentiation but reduced osteoblast differentiation and mineralization on the titanium surface. Interestingly, the cells given the Terrein treatment showed higher resistance towards oxidative stress through the up-regulation of ERK1/2 and FAK activity but the down-regulation of SAPK/JNK and iNOS activity. Moreover, Terrein promoted osteoblast differentiation and bone mineralization to elevate the activity of ALP, SPARC and down-regulate RANKL expression after blocking NF-κB translocation from the cytosol to the nucleus. In conclusion, the presence of Terrein on titanium surfaces increases osteoblast cell growth without inflammation. Moreover, Terrein, as a putative antioxidant agent, may enhance osseointegration by decreasing the level of ROS and having a potentially synergistic effect on osteoblast differentiation.