Survivin downregulation by siRNA sensitizes human hepatoma cells to TRAIL-induced apoptosis

Survivin, an anti-apoptotic protein, is abundantly expressed in a variety of cancer cells, including hepatoma cells, resulting in the resistance of these cells to various apoptotic stimuli. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known to induce cancer cell-specific apoptosis, but hepatoma cells are resistant to TRAIL-induced apoptosis. In the present study, we have examined whether the downregulation of survivin by short interfering RNA (siRNA) promotes spontaneous or TRAIL-induced apoptosis in Huh-7 human hepatoma cells. Survivin siRNA transfection downregulated the expression of survivin in Huh-7 cells and reduced cell viability by 20% through inducing spontaneous apoptosis. TRAIL (1 to 2 ng/ml) only slightly induced apoptosis in Huh-7 cells; however, survivin siRNA transfection apparently enhanced TRAIL-induced apoptosis. These results suggest that the level of survivin is linked to the susceptibility of Huh-7 cells to TRAIL. It is possible that survivin downregulation by siRNA combined with TRAIL administration may provide a new therapeutic strategy against hepatoma.     

Different mechanisms for anti-tumor effects of low- and high-dose cyclophosphamide

It is known that, besides its direct cytotoxic effect as an alkylating chemotherapeutic agent, cyclophosphamide also has immuno-modulatory effects, such as depletion of CD4+CD25+ regulatory T cells. However, its optimal concentration has not yet been fully elucidated. Therefore, we first compared the effects of different doses of cyclophosphamide on T cell subsets including CD4+CD25+ T cells in mice. Cyclophosphamide (20 mg/kg) decreased the numbers of splenocytes, CD4+ and CD8+ T cells by approximately 50%, while a decline in CD4+CD25+ T cell number was more profound, leading to the remarkably lower ratios of CD4+CD25+ T cells to CD4+ T cells. In contrast, 200 mg/kg cyclophosphamide severely decreased the numbers of all the T cell subsets by > 90% although the decreased ratios of CD4+CD25+ T cells to CD4+ T cells were still observed. Next, low-dose cyclophosphamide significantly inhibited in vivo growth of murine hepatoma MH129 tumor in immuno-competent but not immuno-deficient mice. This anti-tumor effect was abolished by CD4+CD25+ T cell repletion. In contrast, high-dose cyclophosphamide exhibited similar anti-tumor effects in both mice. In addition, contrary to antibody-mediated CD4+CD25+ T cell depletion, administration of low-dose cyclophosphamide after tumor inoculation was more efficacious than the prior administration. Our data show that low-dose cyclophosphamide selectively depletes CD4+CD25+ T cells, leading to enhanced anti-tumor effects against pre-existing tumors, while the anti-tumor effect of high-dose cyclophosphamide is solely attributed to its direct cytotoxicity. These findings appear to be highly crucial in a clinical setting of combined chemotherapy and immunotherapy for cancer treatment.     

Anti-inflammatory effect of spironolactone on human peripheral blood mononuclear cells

We evaluated the effect of alacepril, CV-11974, and spironolactone on the production of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) in cultured human peripheral blood mononuclear cells stimulated with angiotensin (Ang) II. Alacepril, CV-11974, and spironolactone significantly reduced the enhanced production of MCP-1 and TNF-alpha induced by exogenous Ang II. Specifically, 10 muM of spironolactone significantly reduced cytokine production, compared to the same dose of alacepril or CV-11974. These findings indicate that spironolactone may contribute to ameliorate the prognosis of patients with cardiovascular diseases by reducing Ang II-induced inflammation, although further exploration including determining the mechanisms would be required.     

Inhibition of colon cancer (HT-29) cell proliferation by a triterpenoid isolated from Azadirachta indica is accompanied by cell cycle arrest and up-regulation of p21

Nimbolide, a natural triterpenoid present in the edible parts of the neem tree ( Azadirachta indica), was found to be growth-inhibitory in human colon carcinoma HT-29 cells. Nimbolide treatment of cells at 2.5 - 10 microM resulted in moderate to very strong growth inhibition. Flow cytometric analysis of HT-29 cells showed that nimbolide treatment (2.5 microM, 12 h) caused a 6.5-fold increase in the number of cells (55.6 %) in the G2/M phase compared with the control cells (8.8 %). At 48 h, the cell population in the G2/M phase decreased to 18 %, while that in the G0/G1 phase increased to 52.3 %. Western blot analysis revealed that nimbolide-mediated G2/M arrest was accompanied by the up-regulation of p21, cyclin D2, Chk2; and down-regulation of cyclin A, cyclin E, Cdk2, Rad17. At G0/G1 cell cycle arrest, modulation in the expression of the cell cycle regulatory molecules was also observed. We found that nimbolide-induced growth inhibition and cell cycle arrest were not associated with cellular differentiation. Quantification of cells with respect to the expression of phosphatidylserine in the outer cell membrane showed an increase in apoptotic cells by about 13 % after 48 h of nimbolide treatment.     

Strain differences in the responsiveness between Sprague-Dawley and Fischer rats to nephropathy induced by FYX-051, a xanthine oxidoreductase inhibitor

To determine a rat strain appropriate for carcinogenicity testing of FYX-051, a xanthine oxidoreductase inhibitor, we performed a 4-week oral toxicity study by administering 0.3, 1 and 3 mg/kg, and 1, 3 and 10 mg/kg of FYX-051 to male Sprague-Dawley (SD) and Fischer (F344) rats, respectively. Histopathology revealed that the degree of FYX-051-induced nephropathy was 3-fold stronger in SD rats than in F344 rats. Our previous study demonstrated that the key factor of species differences in FYX-051-induced nephropathy is purine metabolism. This observation led us to examine the involvement of purine metabolism in differences among two strains of rats. However, purine metabolism was proven not to be implicated as an important factor. Subsequently, other factors responsible for the strain differences were examined. FYX-051-induced increases in plasma xanthine concentrations were higher in SD rats than in F344 rats, suggesting more remarkable effects on pharmacodynamics in the former than the latter. Urinary volume was greater in F344 rats administered 10 mg/kg of FYX-051 (6.8 ml/h/kg) than in SD rats administered 3 mg/kg of FYX-051 (5.0 ml/h/kg), implying easier xanthine excretion in the former. Urinary xanthine solubility was 55 mg/dl in F344 rats aged 6 weeks, in contrast to 38 mg/dl in SD rats of the same age. Also, there were no significant differences in exposure levels at the same dose between SD and F344 rats. The outcomes of exposure levels and renal histopathology in both rats suggest the possibility that F344 rats could be exposed to a 3-fold higher amount of drug than SD rats in a carcinogenicity bioassay. The present study, therefore, suggested that strain differences of nephrotoxicity were caused by the combined effects of pharmacodynamics, xanthine excretion capacity, and urinary xanthine solubility. Furthermore, these results indicate that F344 rats would be a suitable strain for the carcinogenicity study of FYX-051.     

Ultrastructure of the anterior neurohypophysis and the pars distalis of the lamprey,Lampetra tridentata

The pars distalis of lampreys is divisible into rostral and caudal regions. Both regions contain secretory cells of several types and a small number of nonsecretory cells. Nerve fibers could not be identified in the pars distalis. No vascular connections between pars distalis and brain were observed.The neurohypophysis is differentiated into anterior and posterior regions. The posterior neurohypophysis is associated with pars intermedia and may be considered equivalent to the pars nervosa of higher vertebrates. The anterior neurohypophysis is a thin sheet of tissue that forms the ventral border of the third ventricle; it is separated from pars distalis by a thin layer of connective tissue. The anterior neurohypophysis consists of a juxtaventricular ependymal layer, an intermediate nerve fiber layer, and a peripheral nerve terminal layer. The nerve fibers and terminals contain neurosecretory granules of several types. The ultrastructure of anterior neurohypophysis is similar to that of the median eminence of higher vertebrates and might represent a median eminence without portal vessels. However, the absence of nervous and vascular connections between anterior neurohypophysis and pars distalis would seem to affect the functional value of this “median eminence” and might represent a “primitive” neuroglandular relationship from which other vertebrates have evolved.     

Olivary Hypertrophy in a Case with Palatal Myoclonus:Light- and Electron-microscopic Study

Abstract: This is a report on the ultrastructural finding of the olivary hypertrophy in a case with palatal myoclonus. By light microscopy two types of neuronal changes were observed in the inferior olivary nucleus, i.e. the central chromatolysis and cytoplasmic vacuolation. Both types were also recognized by electron microscopy and the cytoplasmic vascuolation was identified as the vesiculated endoplasmic reticulum. In the reactive astrocytes, mitochondria were strikingly proliferated.     

Gene encoding human p250 T-cell activation antigen maps to human chromosome 11

Human p250 T-cell activation antigen detected by a monoclonal antibody, B1.19.2, is a single peptide antigen with a molecular weight of 250 kilodaltons and is classified serologically into cluster of differentiation, CDw26. Concordance between the presence of human chromosome 11 and the reactivity with B1.19.2 was demonstrated by chromosomal analysis of 23 clones derived from three hybrid series obtained from the fusion of human activated lymphocytes or T-cell chronic lymphocytic leukemia cells and BW5147 mouse T-cell leukemic cells. The results indicated that the presence of chromosome 11 was essential for the expression of p250 T-cell activation antigen. Moreover, the gene for this antigen was assigned to chromosome 11pterp11.2 by analysis of the hybrid clones retaining the translocated chromosome of 11.