Berberine prevents nitric oxide-induced rat chondrocyte apoptosis and cartilage degeneration in a rat osteoarthritis model via AMPK and p38 MAPK signaling.

Chondrocyte apoptosis is an important mechanism involved in osteoarthritis (OA). Berberine (BBR), a plant alkaloid derived from Chinese medicine, is characterized by multiple pharmacological effects, such as anti-inflammatory and anti-apoptotic activities. This study aimed to evaluate the chondroprotective effect and underlying mechanisms of BBR on sodium nitroprusside (SNP)-stimulated chondrocyte apoptosis and surgically-induced rat OA model. The in vitro results revealed that BBR suppressed SNP-stimulated chondrocyte apoptosis as well as cytoskeletal remodeling, down-regulated expressions of inducible nitric oxide synthase (iNOS) and caspase-3, and up-regulated Bcl-2/Bax ratio and Type II collagen (Col II) at protein levels, which were accompanied by increased adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and decreased phosphorylation of p38 mitogen-activated protein kinase (MAPK). Furthermore, the anti-apoptotic effect of BBR was blocked by AMPK inhibitor Compound C (CC) and adenosine-9-ß-D-arabino-furanoside (Ara A), and enhanced by p38 MAPK inhibitor SB203580. In vivo experiment suggested that BBR ameliorated cartilage degeneration and exhibited an anti-apoptotic effect on articular cartilage in a rat OA model, as demonstrated by histological analyses, TUNEL assay and immunohistochemical analyses of caspase-3, Bcl-2 and Bax expressions. These findings suggest that BBR suppresses SNP-stimulated chondrocyte apoptosis and ameliorates cartilage degeneration via activating AMPK signaling and suppressing p38 MAPK activity.

Construction of a plasmid for overexpression of human circadian gene period2 and its biological activity in osteosarcoma cells.

Beyond their established role in the mammalian circadian clock, recent studies have confirmed that the circadian genes have been implicated in tumor onset and progression. Currently, the biological effects of circadian genes on osteosarcoma cells' proliferation and migration are not well understood. Period2 (Per2) is one of the core circadian genes that act as master regulators of development and is frequently dysregulated in several cancers. However, the effects of human Per2 (hPer2) on the biological behavior of osteosarcoma cells are rarely reported. In the present study, to address the expression of hPer2 in osteosarcoma cells, the pEGFP-N1-hPer2 eukaryotic expression vector was constructed and transfected into cultured MG63 cells using Lipofectamine™ 2000. The overexpression of hPer2 in MG63 cells was verified by qRT-PCR and Western blotting, respectively. Finally, we investigated the effects of hPer2 protein overexpression on MG63 cells' viability, cycle, apoptosis, and invasive ability. In conclusion, the recombinant pEGFP-N1-hPer2 plasmid had been constructed successfully and expressed effectively in MG63 cells. Furthermore, results also showed that the viability, proliferation, and invasive abilities were suppressed, and the apoptosis was enhanced in MG63 cells. This preliminary study provides ground work for further research on the roles of circadian gene hPer2 in osteosarcoma cells MG63 and would offer promise for the development of novel therapeutic strategies in the treatment of osteosarcoma.

Doxorubicin Inhibits Proliferation of Osteosarcoma Cells Through Upregulation of the Notch Signaling Pathway.

Doxorubicin plays a major role in the treatment of osteosarcoma disorders. The Notch signaling pathway exerts various biological functions, including cell proliferation, differentiation, and apoptosis. In the present study, we investigated the effects of different doses of doxorubicin on proliferation and apoptosis of osteosarcoma cells with or without Notch signaling. Results found that cellular viability was downregulated while caspase 3 activity and expression were promoted in osteosarcoma cells following treatment with various doses of doxorubicin for 24, 48, and 72 h, and the effects showed a dose- and time-dependent manner. Furthermore, it was found that various doses of doxorubicin activated the Notch signaling pathway, shown by the elevated expression of Notch target genes NOTCH1, HEY1, HES1, AND HES5. It was further proved that, after small interfering RNA (siRNA)-mediated knockdown of Notch, the effects of doxorubicin on the viability and apoptosis of osteosarcoma cells were significantly reduced. It was indicated that doxorubicin treatment reduced the proliferation and promoted the apoptosis of osteosarcoma cells, and this effect was mediated by the Notch signaling pathway.