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

细胞凋亡是肿瘤对放射或化疗敏感性的重要因素，目的研究两种不同放射敏感性的大鼠卵黄囊瘤细胞系对紫杉醇敏感性的差异以及紫杉醇与放射联合应用的增敏作用。NMT-1是亲本放射敏感细胞系，NMT-1 R是变体放射抗性细胞系。NMT-1和NMT-1 R细胞对紫杉醇的敏感性相近，DO分别为5.15 nM和5.02 nM。20 nM紫杉醇作用24小时后DNA断裂的发生率为12.4（± SD）。[）NMT-1为3.3%，[]SY. ±-为13.0。紫杉醇与放射联合作用于两种细胞株均表现出超累加效应，且仅在G2 M期细胞聚集达到高峰时才表现出超累加效应，紫杉醇对两种放射敏感性不同的细胞株均表现出相同程度的细胞毒效应，其原因是紫杉醇诱导细胞凋亡。在两种细胞系中观察到12 h预处理对辐射的超累加效应。紫杉醇与照射联合使用可能对具有不同放射敏感性成分的肿瘤有效。

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.