Oligomycin A enhances apoptotic effect of TRAIL through CHOP-mediated death receptor 5 expression.

Development of resistance to TNF-related apoptosis-inducing ligand (TRAIL) in tumor cells is one of the important problems in cancer treatment. Despite the previous report demonstrating that oligomycin suppressed TNF-induced apoptosis, in our screening of small molecules enhancing cancer cell death to TRAIL, oligomycin A (OMA) was found to enhance TRAIL-induced apoptosis in HeLa cells. CCAAT/enhancer-binding protein homologous protein (CHOP) was found to directly bind to death receptor 5 (DR5) promoter through endoplasmic reticulum stress (ER-stress) signaling and sensitize the cells to TRAIL. Among ER-stress associated proteins, OMA triggered the inositol-requiring enzyme 1 (IRE1) signaling pathway, leading to X-binding protein 1 (XBP1) splicing, CHOP expression and DR5 upregulation. In contrast, small-interfering RNA (siRNA) of CHOP reduced the number of apoptotic cells in response to the co-treatment of TRAIL and OMA. Collectively, our data suggest that OMA enhances apoptotic death of cervical cancer cells to TRAIL through upregulation of CHOP-mediated DR5 expression following ER-stress.

Ginsenoside Rh2 inhibits osteoclastogenesis through down-regulation of NF-κB, NFATc1 and c-Fos.

Ginsenoside Rh2 is one of the most active components of red ginseng, controlling cancer and other metabolic diseases including osteoclast differentiation. However, the molecular mechanism underlying the inhibition of osteoclast differentiation by ginsenoside Rh2 remains poorly understood. In the present study, it was found that ginsenoside Rh2 suppressed osteoclast differentiation from bone marrow macrophages (BMMs) treated with receptor activator of nuclear factor κB ligand (RANKL) without any cytotoxicity. Ginsenoside Rh2 significantly reduced RANKL-induced expression of transcription factors, c-Fos and nuclear factor of activated T-cells (NFATc1), as well as osteoclast markers, TRAP and OSCAR. In defining the signaling pathways, ginsenoside Rh2 was shown to moderately inhibit NF-κB activation and ERK phosphorylation in response to RANKL stimulation in BMM cells without any effect on p38 and c-Jun N-terminal kinase (JNK). Finally, ginsenoside Rh2 blocked osteoporosis in vivo as confirmed by restored bone mineral density (BMD) and other markers associated osteoclast differentiation. Hence, it is suggested that ginsenoside Rh2 could suppress RANKL-induced osteoclast differentiation in vitro and in vivo through the regulation of c-Fos and NFATc1 expressions, not excluding the involvement of NF-κB and ERK. Ginsenoside Rh2 is also suggested to be developed as a therapeutic drug for prevention and treatment of osteoporosis.

Asperlin induces G2/M arrest through ROS generation and ATM pathway in human cervical carcinoma cells.

We exploited the biological activity of an antibiotic agent asperlin isolated from Aspergillus nidulans against human cervical carcinoma cells. We found that asperlin dramatically increased reactive oxygen species (ROS) generation accompanied by a significant reduction in cell proliferation. Cleavage of caspase-3 and PARP and reduction of Bcl-2 could also be detected after asperlin treatment to the cells. An anti-oxidant N-acetyl-L-cysteine (NAC), however, blocked all the apoptotic effects of asperlin. The involvement of oxidative stress in asperlin induced apoptosis could be supported by the findings that ROS- and DNA damage-associated G2/M phase arrest and ATM phosphorylation were increased by asperlin. In addition, expression and phosphorylation of cell cycle proteins as well as G2/M phase arrest in response to asperlin were significantly blocked by NAC or an ATM inhibitor KU-55933 pretreatment. Collectively, our study proved for the first time that asperlin could be developed as a potential anti-cancer therapeutics through ROS generation in HeLa cells.

Construction of adiponectin-encoding plasmid DNA and gene therapy of non-obese type 2 diabetes mellitus.

Adiponectin (ADN), an insulin-sensitizing adipokine, stimulates glucose uptake, inhibits gluconeogenesis, and plays an important role in improving insulin sensitivity. Since blood levels of ADN are low in type 2 diabetes mellitus (DM), this study was designed to investigate the therapeutic effectiveness of increasing the ADN level through injection of plasmid DNA encoding ADN in type 2 DM. A non-obese type 2 DM mouse model was established via combined administration of streptozotocin with nicotinamide and exhibited significantly higher plasma glucose concentration and insulin resistance compared with normal controls according to oral glucose tolerance and insulin challenge tests. Plasmid DNA encoding mouse ADN from differentiated NIH3T3 adipocytes was constructed in pVAX1 (pVAX/ADN). Transfection of pVAX/ADN into various cell lines including HeLa, HT22, HEK293, HepG2, and SK-Hep1 cells, increased ADN mRNA expression levels in a dose-dependent manner. The administration of pVAX/ADN into non-obese type 2 DM mice via tail vein significantly increased the blood level of ADN and decreased the plasma glucose concentration. Moreover, the parameters related to insulin resistance (HOMA-IR) and insulin sensitivity (QUICKI) were significantly improved. These results suggest that ADN gene therapy could be a clinically effective tool for the treatment of type 2 DM.

Synergistic decrease in blood pressure by captopril combined with losartan in spontaneous hypertensive rats.

This study was designed to examine the anti-hypertensive effect of the combination therapy of captopril with losartan by oral administration using both independent and cross-over experimental protocols. In independent experimental protocols, four different groups of spontaneous hypertensive rats (SHR) were treated for 1 or 2 weeks: control, captopril (20 mg/kg/day), losartan (20 mg/kg/day), and combination captopril (10 mg/kg/day) with losartan (10 mg/kg/day). In cross-over protocols, each SHR received all four treatments for 1 or 3 days with an interval of several days between each injection for washing-out and return to high blood pressure (BP) levels. BP and heart rate (HR) were measured in conscious telemetered SHR. According to the results from the independent protocol, regardless of a 1- or 2-week administration period, combination therapy with low doses of captopril and losartan had a greater anti-hypertensive effect than individual high-dose monotherapy. Similarly, results from the cross-over protocol showed that regardless of 1-day or 3-day administration, the decrease in BP in the 11(th) and 12(th) hour after administration was greatest with the combination of low-dose captopril and losartan. Therefore, combination therapy with low doses of captopril with losartan lowered BP to a greater extent than a high dose of either individual monotherapy.