| Objective:Antheraea Pernyi cecropin was administered in vivo and in vitro to observe its antitumor activity in human nasopharyngeal carcinoma cell line CNE2. The experiment was also try to clarify the antitumor mechanisms.Methods:1. Cytotoxicity of Antheraea Pernyi cecropin in human nasopharyngealcarcinoma cell line CNE2. As the most useful and efficient anti-NPC chemotherapy medicine, 5-Fluorouracil was contrasted as the positive chamical treatment. MTT colorimetric assay was applied to detect cytotoxicity of cecropin in human nasopharyngeal carcinoma cell line CNE2. Apoptosis rate of cells double marked with Annexin V/PI was examined by flow cytometry. Anti-tubulin monoclonal antibody was used to detect the cytoskeleton change. Ultrastructure change of CNE2 cell was observed under transmission electron microscope.2. Antitumor effect of cecropin on CNE2-bearing nude mice. Nude mice with nasopharyngeal carcinoma were established to conduct interference treatment. The mice were randomly divided into four groups, the group of control, 5-FU, cecropin of intraperitoneal injection and cecropin of intra-tumoral injection. All groups were treated once a day for three days continued and sacrificed on 10th day. Numeration of leucocyte in peripheralblood were recorded. Tumors were weighed precisely and tumor inhibitory rates of each groups were compared. The tumor, heart, liver, kidney were conducted by pathological examination to analysis the therapeutic efficacy and toxic effect of cecropin.Results1. Cytotoxicity in vitroCecropin appeared an obvious dosage and effect relatio on human nasopharyngeal carcinoma cell line CNE2. When the concentration and culture time increased, Cecropin increased the ability of killing and suppressing the cell (P<0.01). On the action time of 72h, 300 μ mol/L cecropin got an average tumor suppressing rate of 84.78% and the ICso of cecropin was 222μ mol/L. The tumor suppressing rates of cercropin were obviously lower than that of 5-FU (P<0.01). 300μ mol/L cecropin had similar tumor suppressing rates to 75 μ mol/L 5-FU on the action time of 24h and 48h (P>0.05), and was better than 75μ mol/L 5-FU on 72h (P<0.01). Apoptotic rate was also increased when the concentration increased and reached the high peak in about 48 hours. When the culture time was longer than 72 hours, the apoptotic rate decreased. After treated with cecropin, the immunohistochemistry staining showed maldistributions of the cellular skeleton. Being observed under the light microscopy, the cytoskeleton had anomalous forms, and bacame confused and shrunken. The cell ultrastructure was demaged seriously under the transmission electron microscope after the treatment of cecropin. The cell membranes were fragmentized and some components in the cytoplasm dispersed outside. The mitochondria appeared to be electron density reduction, swollen and broken in cristae. Apoptotic cells could be seen. Heterochromatin assembled on the edge of the nucleus and euchromatin rarefied in the middle of the nucleus. Organells were normal and regular in the main.2. Therapeutic efficacy in vivoCecropin showed clear inhibitory activity against mice bearing humannasopharyngeal carcinoma cell line CNE2. Each treatmental groups has significant difference to the control group (P<0.01). Comparison between the 5-FU group and the intra-tumoral injection of cecropin group didn't show any significant difference (P>0.05). Two groups of cecropin had a significant difference (P<0.01). Tumor inhibitory rate of 5-FU, cecropin intra-tumoral injection and cecropin intraperitoneal injection reached to 82.72%, 81.48% and 59.26% separately. Routine pathological section observation of tumor tissues revealed a large area of necrosis and hemorrhage associated with light leukocyte infiltration after the treatment of 5-FU. There were snips of hemorrhage and necrosis associated with light leukocyte infiltration when the mice were treated by cecropin intraperitoneally. Large areas of necrosis and hemorrhage could als...
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