Human malignant glioma cells are characterized by local invasion. In the present study, we investigated the role of osteopontin (OPN) in the invasiveness of human glioma cells isolated from grade IV tumors. We found that the expression levels of OPN in these cell lines paralleled matrix metalloproteinase-2 (MMP-2) expression and cell invasiveness potential. When U87MG glioma cells (with a high-OPN expression level) were stably transformed with specific small hairpin RNA to knock down OPN expression, MMP-2 secretion, cell invasiveness, and tumor growth in implanted brains were dramatically reduced. Conversely, forced expression of OPN in GBM-SKH glioma cells (which expressed OPN at a low level) increased MMP-2 secretion, enhanced cell invasiveness, and increased tumor growth in a rodent xenograft model. Expression of OPN was associated with increased expression of vimentin and decreased expression of glial fibrillary acidic protein. Treatment of glioma cells with 5-aza-2′-deoxycytidine (5-aza-dC) suppressed OPN expression in a concentration-dependent manner. Suppression of OPN expression by 5-aza-dC was associated with reductions in MMP-2 secretion, vimentin expression, cell invasion, intravasation, and tumor growth. These data suggest that OPN may play important roles in regulating cell invasion in glioma cells and that 5-aza-dC may serve as a therapeutic agent for human gliomas.

Taken together, these results suggest that Nodal affects energy metabolism through HIF-1α.

Meisoindigo, a derivative of Indigo naturalis, has been used in China for chronic myeloid leukemia. In vitro cell line studies have shown that this agent might induce apoptosis and myeloid differentiation of acute myeloid leukemia (AML). In this study, we explored its mechanisms and potential in AML. NB4, HL-60, and U937 cells and primary AML cells were used to examine its effects and the NOD/SCID animal model was used to evaluate its in vivo activity. Meisoindigo inhibited the growth of leukemic cells by inducing marked apoptosis and moderate cell-cycle arrest at the G(0)/G(1) phase. It down-regulated anti-apoptotic Bcl-2, and up-regulated pro-apoptotic Bak and Bax and cell-cycle related proteins, p21and p27. Furthermore, it induced myeloid differentiation, as demonstrated by morphologic changes, up-regulation of CD11b, and increased nitroblue tetrazolium reduction activity in all cell lines tested. In addition, meisoindigo down-regulated the expression of human telomerase reverse transcriptase and enhanced the cytotoxicity of conventional chemotherapeutic agents, cytarabine and idarubicin. As with the results from cell lines, meisoindigo also induced apoptosis, up-regulated p21 and p27, and down-regulated Bcl-2 in primary AML cells. The in vivo anti-leukemic activity of meisoindigo was also demonstrated by decreased spleen size in a dose-dependent manner. Taking these results together, meisoindigo is a potential agent for AML.

Areca quid (AQ) chewing is a popular oral habit, especially in Southeast Asia cultures, in which children may be engaged in the addictive habit early in their lives. Extracts of areca nuts, the main component of AQ, have been shown to affect the functionality of T-cells. However, the potential influence of ANE on the development of T-cells is unknown. This study, therefore, investigated the impact of areca nut extracts (ANE) on thymocytes and the potential mechanisms of action. Mice administered intraperitoneally with ANE at 1, 5, or 25 mg/kg daily for 5 days showed significant dose-dependent reductions in thymocyte viability. A marked decrease in the total number of thymocytes and the proportion of thymic CD4 þ CD8þ cells was observed in the 25 mg ANE/kg-treated mice, whereas the proportion of CD4 and CD8 single positive and CD4À CD8 À cells was significantly increased. Further examination on the functionality of thymocytes showed that ANE suppress IL-2 production both ex vivo and in vitro. These results suggest that ANE may attenuate the development and functionality of thymic T-cells. ANE also directly induced apoptosis in thymic T-cells through activation of casapase-3 and apoptosis inducing factor (AIF). Collectively, the data suggested that the thymus is a sensitive target to ANE. Early exposure to ANE may interfere with the development and functionality of thymic T-cells.