| Summary: | 碩士 === 國立陽明大學 === 放射醫學科學研究所 === 94 === AIM:
To investigate the combined effect of tetrandrine and radiation on C26 colorectal adenocarcinoma cells in vitro and evaluate the efficacy of chemo-radiotherapy on C26 colorectal adenocarcinoma bearing mice which were transfected with dual tk (herpes simplex virus tupe 1 thymidine kinase, HSV1-tk) and luc (luciferase) genes through plasmid vectors.
METHODS:
We examined the anti-proliferative and apoptosis-inducing activities of tetrandrine with colony formation, flow cytometry, DNA fragmentation, Western blotting and caspase-3 activity assays. In this study, we also evaluated the combined effect of tetrandrine and ionizing radiation on C26/tk-luc tumor-bearing animal model. BALB/c mice were subcutaneously implanted with C26/tk-luc cells and divided into several groups: control, various concentrations of tetrandrine (intra-peritoneal injection), radiation treatment (RT) alone, and combination of tetrandrine with radiation. The therapeutic efficiency was evaluated with multimodalities of caliper, bioluminescent imaging (BLI) and gamma scintigraphy.
RESULTS:
Cytotoxic effect of tetrandrine on C26 cells treated for 3 hours in vitro was found (IC50~10uM). Alteration of cell morphology, caspase-3 activation, DNA fragmentation and dose-dependent induction of apoptosis were observed both in drug alone and combination groups. The tumor growth was delayed in a dose independent manner after various concentrations of tetrandrine treatment. However, the tumor growth rate was significantly inhibited by RT and combination groups, and the latter even showed the synergistic effect. Body weights of all groups showed no significant change. Both skin and hair are also normal for all groups. These results suggest that tetrandrine is not only potentially useful as a chemotherapeutic agent, but a radiosensitizer for colorectal adenocarcinoma treatment.
CONCLUSIONS:
1.Tetrandrine is cytotoxic to C26 murine colorectal
adenocarcinoma cells in vitro due to the induction of
apoptosis mainly through the caspase-3 activation.
2.Tetrandrine sensitizes C26/tk-luc colorectal tumor to
radiation with a synergistic effect. Combination therapy
of TET+RT may have potential as a treatment alternative
in clinic for cancer chemo-radiotherapy.
3.Non-invasive bioluminescent imaging is a useful tool for
the evaluation of the therapeutic efficacy evaluation,
because the same cohort of animals can be screened over
times throughout the treatment without sacrifice.
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