Tea Flavonoids Induced Differentiation of Peripheral Blood-derived Mononuclear Cells into Peripheral Blood-derived Endothelial Progenitor Cells and Suppressed Intracellular Reactive Oxygen Species Level of Peripheral Blood-derived Endothelial Progenitor C

Endothelial dysfunction in atherosclerosis is associated with increasing oxidative stress that could be reversed by antioxidant. Therefore epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and catechin (C) of tea flavonoids were investigated for their roles in regenerating endothelial cell. Peripheral blood mononuclear cells (PB-MNCs) were isolated, plated and cultured in medium with/without treatment of EGCG, ECG, EGC and C. Results showed that among all EGCG, ECG, EGC and C concentrations tested, 12.5 µmol/L was not cytotoxic for peripheral blood-derived endothelial progenitor cells (PB-EPCs). Treatment of EGCG, ECG, EGC or C increased the percentages of CD34, CD133, VEGFR-2 expressions and suppressed hydrogen peroxide-induced percentages of reactive oxygen species (ROS) level in PB-EPCs. Taken together, our current results showed that EGCG, ECG, EGC or C of tea flavonoids could induce differentiation of PB-MNCs into PB-EPCs as well as protect PB-EPCs from oxidative damage by suppresing the intracellular ROS levels.

An Anti-apoptotic Role of NF-κB in TNFα-induced Apoptosis in an Ameloblastoma Cell Line / Oral Science International

Nuclear factor-κB (NF-κB) is involved in the promotion of cell survival in a variety of cell types. The present study focused on the role of NF-κB in TNFα-induced apoptosis in an ameloblastoma. Immunohistochemical staining revealed p65 NF-κB protein to be expressed in ameloblastoma tissues. Furthermore, immunoblotting and immunocytochemistry analyses showed that the stimulation of TNFα in an ameloblastoma cell line (AM-1) induced p65 NF-κB translocation from the cytoplasm to the nucleus, indicating NF-κB activation. These findings were confirmed by an NF-κB luciferase reporter assay, which detected enhanced NF-κB transcription activity of AM-1 cells by TNFα stimulation. Moreover, pretreatment with SN50, a nuclear translocation inhibitor, prior to TNFα stimulation, effectively inhibited TNFα-induced NF-κB activation in AM-1 cells. In order to reveal the role of NF-κB activation during TNFα-induced apoptosis in AM-1 cells, an apoptosis assay was performed, and showed that the potential of TNFα in inducing apoptosis in AM-1 cells was significantly elevated by inhibiting the NF-κB activation. These results suggest that NF-κB plays an anti-apoptotic role in TNFα-induced apoptosis in AM-1 cells.

Inositol hexakisphosphate blocks tumor cell growth by activating apoptotic machinery as well as by inhibiting the Akt/NFkappaB-mediated cell survival pathway.

It has been reported that inositol hexakisphosphate (InsP(6), phytic acid), a natural product, has an anticancer role. However, there is inadequate information regarding the mechanism by which InsP(6) exerts anticancer actions, and the effect requires relatively high concentration of the agent, both of which hinders the usage of InsP(6) as an anticancer drug. In the present study, we investigated the mechanism by which InsP(6) acts as an anticancer agent, and tried to reduce the concentration of effective InsP(6). Treatment of HeLa cells with InsP(6) at 1 mM induced apoptosis, as assessed by counting the cell number, and by Hoechst and TUNEL staining. This is probably mediated by intracellular InsP(6) itself and/or the dephosphorylated forms of metabolized InsP(6), because incubation of HeLa cells with [(3)H]InsP(6) produces dephosphorylated forms such as InsP(4) and InsP(5). Induction of apoptosis by InsP(6) was examined in two ways: inhibition of cell survival signaling and direct induction of apoptosis. Treatment of HeLa cells with tumor necrosis factor (TNF) or insulin stimulated the Akt-nuclear factor kappaB (NFkappaB) pathway, a cell survival signal, which involves the phosphorylation of Akt and IkappaB, nuclear translocation of NFkappaB and NFkappaB-luciferase transcription activity. InsP(6) blocked all these cellular events, but phosphatidylinositol 3-kinase activity was not affected. As well as inhibiting the Akt-NFkappaB pathway, InsP(6) itself caused mitochondrial permeabilization, followed by cytochrome c release, which later caused activation of the apoptotic machinery, caspase 9, caspase 3 and poly (ADP-ribose) polymerase. When InsP(6) was applied together with histone, the effective concentration to induce apoptosis was approximately 10-fold lower. These results revealed that extracellularly applied InsP(6) directly activates the apoptotic machinery as well as inhibits the cell survival signaling, probably by the intracellular delivery followed by a dephosphorylation.