| Glioma is a most common intracranial primary neoplasm, accounting for 40-50% of them. Glioblastoma is the most malignant form and has the worst prognosis. Up to now, glioblastoma remains incurable despite intensive multi-modality treatment including surgical resection, irradiation and chemotherapy. Arsenic trioxide (As2O3) is a kind of effective agent that can induce apoptosis in carcinoma cells, which has been applied for the treatment of leukemia successfully in clinical cases. On the other hand, a lot of experiment studies had proved that Dexamethasone (DEX) could promote apoptosis of many tumor cells alone or in combination with other agents.Objective: The purpose of this study was to evaluate the proliferation-inhibiting and apoptosis-inducing effects of arsenic trioxide or in combination with DEX on human glioblastoma cell line BT-325 in vitro, and to explore the feasibility of arsenic trioxide being applied for the treatment for glioblastoma.Methods: BT-325 cells cultured in vitro were divided into four groups: the control group (group A), the DEX group (group B), the As2O3 group (group C ) including five sub-groups(C1.0, C2.5, C5.0, C7.5 , C10.0, coincident with the concentration of 1-10umol/L As2O3 ), and As2O3 with DEX group (group D) including five sub-groups (D1.0, D2.5, D5.0, D7.5, D10.0). The BT-325 cells in every group were examined by the following methods at different time course:1.Morphology observation of cell: Morphology of BT-325 cells were observed by invert microscope. The cells planted on pieces of covering glass were dyed with acroidine orange (AO) after 24h, 48h or 72h of exposure to agents respectively, then observed in fluorescent light microscope.2.Trypan blue dyeing and cell number counting: BT-325 cells excluding from trypan blue dyeing after 24, 48 or 72h of treatment for cells, were counted in the cell counter to draw the growth curve of cells after 72h.3.MTT method: The cells in four groups were dyed with MTT after 24, 48 or 72h of exposure to agents then detected inhaling light degree with 490nm by enzyme labelled detector to evaluate the cell proliferation inhibiting rate.4.Flow cytometric: The cells were harvested after 48h of exposure to agents and dyed with EB to analyse the cell cycle and apoptosis ratio by flow cytometry.5.Cell DNA fragmentation analysis: Cells were collected and lysed after 48h of treatment with agents, then centrifugalized to separate the fragmented DNA from the intact DNA; the inhaling light degree of them was detected by UV spectrophotometer to evaluate DNA fragmentation rate.Result: 1. As2O3 could inhibit BT-325 cells proliferation ability and make the cell shape change from long shuttle to round or oval in a dose-time dependent manner. In fluorescent light microscope we found that BT-325 cells nucleus condensed that emanated yellow-green light in high concentration groups, which was evident in As2O3 with DEX group, in which yellow-green fragments were observed in the same time.2. BT-325 cells excluding from trypan blue dyeing were above 90% of the total cell number in every groups. As2O3 at 1.0-10.0 umol/L for 24h made BT-325 cells number decrease from 3.02×104/ml to 1.19×104/ml. This tendency was more significant after BT-325 cell were treated for 48 or 72h.3. As2O3 inhibited cell proliferation in a dose-time dependent manner. The significant synergistic effect of As2O3 with DEX on BT-325 was indicated by that cell proliferation inhibitory rate in group D was higher than that in group C (P<0.05).4.Flow cytometry analysis showed that administration of As2O3 resulted in BT-325 cells arrested in G2/M phase and apoptosis. The cell apoptosis rate in group C10.0 (8.29%)was higher than that in group A (P<0.05). There were significant differences in apoptosis ratio between group C and goup D when As2O3 concentration was above 2.5umol/L indicated that As2O3 with DEX could promote BT-325 cells apoptosis.5. As the concentration of As2O3 increasing from 1.0umol/L to 10.0umol/L, DNA fragmentation rate rose from 5.38% (gr...
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