Functional improvement of collagen-based bioscaffold to enhance periodontal-defect healing via combination with dietary antioxidant and COMP-angiopoietin 1.

Scaffolds combined with bioactive agents can enhance bone regeneration at therapeutic sites. We explore whether combined supplementation with coumaric acid and recombinant human-cartilage oligomeric matrix protein-angiopoietin 1 (rhCOMP-Ang1) is an ideal approach for bone tissue engineering. We developed coumaric acid-conjugated absorbable collagen scaffold (CA-ACS) and investigated whether implanting CA-ACS in combination with rhCOMP-Ang1 facilitates ACS- or CA-ACS-mediated bone formation using a rat model of critically sized mandible defects. We examined the mechanisms by which coumaric acid and rhCOMP-Ang1 regulate behaviors of human periodontal ligament fibroblasts (hPLFs). The CA-ACS exhibits greater anti-degradation and mechanical strength properties than does ACS alone. Implanting CA-ACS loaded with rhCOMP-Ang1 greatly enhances bone regeneration at the defect via the activation of angiogenic, osteogenic, and anti-osteoclastic responses compared with other rat groups implanted with an ACS alone or CA-ACS. Treatment with both rhCOMP-Ang1 and coumaric acid increases proliferation, mineralization, and migration of cultured hPLFs via activation of the Ang1/Tie2 signaling axis at a greater rate than treatment with either of them alone. Collectively, this study demonstrates that CA-ACS impregnated with rhCOMP-Ang1 enhances bone regeneration at therapeutic sites, and this enhancement is associated with a synergistic interaction between rhCOMP-Ang1-mediated angiogenesis and coumaric acid-related antioxidant responses.

Caspase-independent death of human osteosarcoma cells by flavonoids is driven by p53-mediated mitochondrial stress and nuclear translocation of AIF and endonuclease G.

Flavonoids have antioxidant and antitumor promoting effects. Rhus verniciflua Stokes (RVS) is a flavonoid-rich herbal medicine that has long been used in Korea as both a food additive and antitumor agent. It was previous reported that a purified flavonoid fraction prepared from RVS, herein named RCMF (the RVS chloroform-methanol fraction), inhibited the proliferation and induced apoptosis in human osteosarcoma (HOS) cells. This study examined the mechanisms involved in the RCMF-mediated apoptosis in HOS cells. RCMF was shown to be capable of inducing apoptosis in HOS cells by inducing p53 in the cells resulting in the decrease in Bcl-2 level, activation of Bax, and cytoplasmic release of cytochrome c, which led to the translocation of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) into the nucleus. However, the RCMF-induced apoptosis was suppressed by transfecting the cells with antisense p53 oligonucleotides but not by treating them with a MAPK or caspase inhibitor. This suppression occurred through the regulation of Bcl-2 members as well as by preventing the nuclear translocation of the mitochondrial apoptogenic factors. Overall, it appears that p53-mediated mitochondrial stress and the nuclear translocation of AIF and EndoG are mainly required for the apoptosis induced by RCMF.

Flavonoids purified from Rhus verniciflua Stokes actively inhibit cell growth and induce apoptosis in human osteosarcoma cells.

Many studies have suggested that dietary flavonoids are anticancer agents that induce the apoptosis of cancer cells. However, the effects of flavonoids on the induction of apoptosis in osteosarcoma cells are unclear. Previously, a flavonoid fraction, consisting mainly of protocatechuic acid, fustin, fisetin, sulfuretin, and butein, herein named RCMF (the RVS chloroform-methanol fraction), was prepared from a crude acetone extract of Rhus verniciflua Stokes (RVS). This study evaluated the effects of RCMF on the proliferation and apoptosis using human osteosarcoma (HOS) cells. The mechanism of growth inhibition of the HOS cells by the flavonoid fraction, RCMF, was also assessed. The results demonstrated that RCMF exhibited sensitive growth inhibition and induced apoptosis in HOS cells. PARP cleavage was closely associated with the RCMF-induced apoptosis of the HOS cells. Furthermore, the activation of caspase 8 and Bax, the inhibition of Bcl-2 expression, and the release of cytochrome c are believed to be involved in the RCMF-mediated apoptosis. Collectively, these findings suggest that RCMF is an agent which may be capable of inducing sensitive growth inhibition and apoptosis in HOS cells.

Selective antiproliferative and apoptotic effects of flavonoids purified from Rhus verniciflua Stokes on normal versus transformed hepatic cell lines.

Considerable attention is being concentrated on dietary flavonoids in developing novel cancer-preventive approaches due to their potential ability to induce selective apoptosis of cancer cells. In this study, we prepared a flavonoid-containing fraction from a crude acetone extract of Rhus verniciflua Stokes (RVS), traditionally used as a food additive and as an herbal medicine, and named RVS chloroform-methanol fraction (RCMF). We evaluated the effects of RCMF on proliferation and apoptosis using mouse embryonic primary hepatic cells (MPHC), embryonic normal hepatic cell line (BNL CL.2), and its SV40-mediated transformed cell line (BNL SV A.8). We also investigated the effects of RCMF on the antioxidant defense system in those cells. This study demonstrated that RCMF exhibited a selective growth inhibition and apoptosis induction on transformed cells. BNL SV A.8 cells were more sensitive to RCMF-mediated cytotoxicity than were MPHC or BNL CL.2. RCMF-mediated reduction of MnSOD activity and glutathione (GSH) content in BNL SV A.8 cells is thought to be associated with RCMF-induced apoptosis. Our findings suggest that RCMF is an agent which may be capable of inducing growth inhibition and apoptosis of hepatic tumor cells.

Inhibitory effects of glycoprotein-120 (G-120) from Ulmus davidiana Nakai on cell growth and activation of matrix metalloproteinases.

Excessive breakdown of extracellular matrix by metalloproteinases (MMPs) occurs in many pathological conditions. Consequently, methods for inhibiting MMP activity have therapeutic potential. In this study, we investigated the effect of G-120, a 120 kDa glycoprotein purified from the Oriental herbal plant, Ulmus davidiana Nakai (UDN), on the activity and production of several MMPs by evaluating its growth inhibitory effect on NIH 3T3 cells. Tritium uptake assays showed that proliferation of NIH 3T3 cells was strongly suppressed, and G-120-mediated inhibition of DNA synthesis proved to involve a cytostatic, rather than a cytotoxic, effect, as shown by cytotoxicity and apoptosis assays. More importantly, G-120 strongly reduced the gelatinolytic and collagenase activities of MMP proteins, as well as expression of MMP-2 and MMP-9. Electrophoretic mobility shift assays revealed that it suppressed the DNA binding activity of NF-kappaB. Collectively, our observations show that G-120 strongly inhibits the activation of MMPs and NF-kappaB.