N-acetylcysteine stimulates osteoblastic differentiation of mouse calvarial cells.

Estrogen deficiency causes osteoporosis via increased generation of reactive oxygen species (ROS), and thus, antioxidants may prove to be the effective therapeutic candidates. We examined the effects of the antioxidant N-acetylcysteine (NAC) on osteoblastic differentiation in mouse calvarial cells. NAC (10-30 mM) enhanced alkaline phosphatase activity, mRNA expression of osteoblast differentiation-associated genes and mineralized nodule formation. It also increased expression of bone morphogenetic proteins-2, -4, and -7. The osteogenic activity of NAC was partially reduced by inhibition of glutathione synthesis. Since caffeic acid phenethyl ester did not stimulate osteoblast differentiation, it is unlikely that ROS scavenging activity of NAC is sufficient for osteogenic activity. We observed that NAC suppressed small GTPase RhoA activity and activation of RhoA by Pasteurella multocida toxin suppressed the osteogenic activity of NAC. These results suggest that NAC might exert its osteogenic activity via increased glutathione synthesis and inhibition of RhoA activation.

The structure-activity relationships of 2,4(1H,3H)-pyrimidinedione derivatives as potent HIV type 1 and type 2 inhibitors.

Since the discovery of the 2,4 (1H,3H)-pyrimidinediones as potent non-nucleoside inhibitors of the HIV-1 reverse transcriptase (RT) this class of compounds has yielded a number of N-1 acyclic substituted pyrimidinediones with substantial antiviral activity, which is highly dependent upon their molecular fit into the binding pocket common to this inhibitory class. We have specifically examined the structure activity relationships of compounds with chemical modification made by substituting homocyclic rather than acyclic moieties at N-1 of the pyrimidinedione. Seventy-four compounds were synthesized and evaluated for antiviral activity against HIV-1 and HIV-2. The homocyclic modifications resulted in compounds with significant activity against both HIV-1 and HIV-2, suggesting these compounds represent a new class of non-nucleoside RT inhibitors. The structure-activity relationship (SAR) evaluations indicated that cyclopropyl, phenyl and 1- or 3-cyclopenten-1-yl substitutions at the N-1 of the pyrimidinedione, the addition of a methyl linker between the cyclic moiety and the N-1 and the addition of a benzoyl group at the C-6 of the pyrimidinedione had the greatest contribution to antiviral activity. Five pyrimidinedione analogues with therapeutic indexes (TIs) > 450,000 and a specific analogue (1-cyclopropylmethyl-5-isopropyl-6-(3,5-dimethylbenzoyl)-2,4(1H,3H)-pyrimidinedione), which exhibited a TI of > 2,000,000, were identified. None of the analogues were cytotoxic to target cells at the highest in vitro test concentration, which is the upper limit of compound solubility of the analogues in aqueous solution. Thus, we have identified a series of pyrimidinediones with substantially improved antiviral efficacy and range of action and with significantly reduced cellular cytotoxicity.

Anti-angiogenic and anti-tumor apoptotic activities of a topoisomerase II inhibiting agent SJ-8026.

A new piperazine derivative, SJ-8026, is a synthetic anti-cancer agent which exhibits topoisomerase II-inhibiting activities. In this study, we investigated the possibility that this compound inhibits angiogenesis and induces tumor-cell apoptosis using bovine aortic endothelial cells (BAECs) and human hepatocellular carcinoma cells (HepG2) as a model system. in vivo, SJ-8026 decreased the neovascularization of chick embryos and the basic fibroblast growth factor-induced angiogenesis in the chorioallantoic membrane and the mouse Matrigel implants. in vitro, SJ-8026 treatment resulted in the inhibition of proliferation, migration, invasion and tube formation in BAECs. In addition, the treatment of SJ-8026 in HepG2 cells reduced the cell viability, and caused the production of fragmented DNA and the morphological changes corresponding to apoptosis including condensed and fragmented DNA. SJ-8026 also elicited the release of cytochrome c and the activation of caspase-3. Therefore, it is possible that SJ-8026 functions as both angiogenesis inhibitor and apoptosis inducer. Taken together, these results suggest that SJ-8026 may be a candidate for strong anti-cancer agent with the ability to inhibit the angiogenesis of endothelial cells and to induce the apoptosis of tumor cells.

Anti-angiogenic and anti-tumor apoptotic activities of SJ-8002, a new piperazine derivative.

A new piperazine derivative, SJ-8002, is a synthetic anti-cancer agent which exhibits microtubule-inhibiting activities. In this study, we investigated the possibility that this compound inhibits angiogenesis and induces tumor-cell apoptosis using bovine aortic endothelial cells (BAECs) and human hepatocellular carcinoma cells (HepG2) as a model system, respectively. In vivo, SJ-8002 decreased the neovascularization of chick embryos and the basic fibroblast growth factor (bFGF)-induced angiogenesis in the chorioallantoic membrane (CAM) and the mouse Matrigel implants, respectively. In vitro, SJ-8002 treatment resulted in the inhibition of proliferation, migration, invasion and tube formation, and of matrix metalloproteinase-2 (MMP-2) expression in BAECs. In addition, the SJ-8002 treatment in HepG2 cells reduced cell viability, and caused the production of fragmented DNA and the morphological changes corresponding to apoptosis including condensed and fragmented DNA in a concentration-dependent manner. SJ-8002 also elicited the release of cytochrome c and the activation of caspase-3. Therefore, it is possible that SJ-8002 functions as both angiogenesis inhibitor and apoptosis inducer. Taken together, these results suggest that SJ-8002 may be a candidate for strong anti-cancer agent with the ability to inhibit the angiogenesis of endothelial cells and to induce the apoptosis of tumor cells.

Microtubule inhibitory effects of various SJ compounds on tissue culture cells.

SJ compounds (SJ8002 and related compounds) are a group of novel anticancer agents (Cho, Chung, Lee, Kwon, Kang, Joo, and Oh. PCT/KR02/00392). To explore the anticancer mechanism of these compounds, we examined the effect of SJ8002 on microtubules of six human cell lines. At a high concentration (2 microg/mL), SJ8002 effectively disrupted microtubules of the six cell lines within 1 h. At lower concentrations (0.05 to approximately 1.0 microg/mL), the antimicrotubule activity of SJ8002 varied defending on cell lines. The inhibition of in vitro polymerization of pure tubulin by SJ8002 suggested that SJ8002 acts on free tubulin, inhibits the polymerization of tubulin dimer into microtubules, and hence induces the depolymerization of microtubules.