Radio- or chemo-sensitivity and analysis of gene transduction for induction of apoptosis for human tumor cell

据报道，凋亡性死亡是影响肿瘤放射或化疗敏感性的重要因素。目的探讨两种不同放射敏感性的大鼠卵黄囊肿瘤细胞系通过不同凋亡诱导方式对紫杉醇的敏感性及紫杉醇联合照射致敏作用的差异。NMT-1为亲本辐射敏感细胞系，NMT-1R为变异型辐射抗性细胞系。克隆实验显示，NMT-1和NMT-1R对紫杉醇的敏感性几乎相同，分别为5.15 nM和5.02 nM。暴露于紫杉醇24 h后，两种细胞系均出现大量凋亡细胞和DNA阶梯形成。暴露于20 nM紫杉醇24 h后DNA断裂率为12.4 （[SY.+-]）。[) NMT-1为3.3%，SY.+-为13.0。[) NMT-1R为1.9%。在紫杉醇处理后12 h，两种细胞系仅在G2M期细胞积累达到峰值时，紫杉醇联合辐射均表现出超加性效应。紫杉醇对两种放射敏感性不同的细胞系具有相同程度的细胞毒作用，其机制是诱导细胞凋亡。预处理12 h后，两种细胞系均表现出超加性效应。紫杉醇联合照射对具有不同放射敏感性成分的肿瘤可能有效。

Apoptotic death is reported to be important factor for radio- or chemo-sensitivity to tumor.Purpose is to investigate the differences between two rat yolk sac tumour cell lines with different radiosensitivities by different induction of apoptotic cells in paclitaxl sensitivity and in the sensitizing effects of paclitaxl in combination with irradiation. NMT-1 is a parent radiosensitive cell line and NMT-1R is a variant radioresistant cell line. Clonogenic assay demonstrated almost the same paclitaxl sensitivity with Do of 5.15 nM in NMT-1 and 5.02 nM in NMT-1R.Many apoptotic cells and DNA ladder formations were observed at 24 h after exposure to paclitaxl in both cell lines. The incidences of DNA fragmentation after 24 h exposure to 20 nM paclitaxl were 12.4 (]SY.+-。[) 3.3 % for NMT-1, and 13.0(]SY.+-。[) 1.9 % for NMT-1R.Paclitaxl showed a supra-additive effect in combination with radiation in both cell lines at 12 h after paclitaxl treatment only when the accumulation of cells in the G2M phase reached its peak.Paclitaxl had the same degree of cytotoxic effect in two cell lines with different radiosensitivity due to the induction of apoptosis. A supra-additive effect to radiation was observed with 12 h pretreatment in both cell lines. Paclitaxl may be effective for tumors with a component of different radiosensitivity in combination with irradiation.