The combination effects of HER2-targeted antibody therapy and radiotherapy : the elucidation of the most suitable timing that focused its attention on cell cycles.

本研究的目的是评价抗HER-2抗体曲妥珠单抗对乳腺癌细胞系KPL-4的增殖、细胞周期分布和放射敏感性的影响。然后在分析前将细胞暴露于曲妥珠单抗（0-200 μ g/ml）24、48或72小时。使用具有Cell Quest和ModFit LT程序的FACScan细胞分选仪分析细胞核的DNA-PI荧光。分析DNA分布以确定细胞周期的G 0/G1、S和G2/M期的细胞群体。用钴-60 γ射线照射器分别照射2、4和8戈伊的细胞，在有无曲妥珠单抗的情况下，细胞周期分布和照射效率均无明显差异。将KPL-4细胞在1% DCC-FBS培养基中培养48小时。然后将细胞暴露于曲妥珠单抗（0-200 μ g/ml）和含有10%FBS的培养基中24、48或72小时，然后进行分析。曲妥珠单抗诱导细胞周期G 0/G1期细胞分数的浓度依赖性增加。这种G 0/G1期阻滞与S期细胞的浓度依赖性减少有关。KPL-4细胞在1% DCC-FBS培养液中培养48 h后，加入200 μ g/ml曲妥珠单抗，对KPL-4细胞的辐射敏感性有相加作用，而在10% FBS培养液中培养48 h后，加入曲妥珠单抗与不加入曲妥珠单抗对KPL-4细胞的辐射敏感性无明显差异。KPL-4细胞在含1%DCC处理的胎牛血清的培养液中孵育后，曲妥珠单抗可使细胞周期阻滞于G 0/G1期，并对放射敏感性有相加作用。如果曲妥珠单抗能够影响细胞周期，曲妥珠单抗联合放疗可能对HER 2过表达的乳腺癌有治疗作用。

The purpose of this study was to evaluate the effect of an anti-HER-2 antibody trastuzumab on the proliferation, cell cycle distribution, and radiosensitivity of breast cancer cell line.The human breast cancer cell line, KPL-4, which naturally overexpresses HER-2 and is sensitive to anti-HER-2 antibody (trastuzumab). The cells were then exposed to trastuzumab (0-200 g/ml) for 24, 48, or 72 h before analysis. The nuclei were analyzed for DNA-PI fluorescence using a FACScan cell sorter with the Cell Quest and ModFit LT programs. The DNA distribution was analyzed to determine the population of cells in G0/G1, S, and G2/M phases of the cell cycle. The cells received gamma ray irradiation at a dose of 2, 4 or 8 Gy using a cobalt-60 gamma ray irradiator.There were no detectable differences in the distribution of cell cycle and the efficiency of irradiation between with and without trastuzumab. KPL-4 cells were cultured for 48 h in 1% DCC-FBS medium. The cells were then exposed to trastuzumab (0-200 g/ml) with medium containing 10% FBS for 24, 48, or 72 h before analysis. Trastuzumab induced concentration-dependent increase in the fraction of cells in G0/G1 phase of the cell cycle. This G0/G1 arrest was associated with concentration-dependent decrease of cells in S phase. Treatment with 200 g/ml trastuzumab had additive effect on the radiosensitivity of KPL-4 cells were cultured for 48 h in 1% DCC-FBS medium before trastuzumab treatment.There were no detectable differences in the efficiency of irradiation between with and without trastuzumab, when KPL-4 cells were cultured in 10% FBS medium. After KPL-4 cells incubated in medium with 1% DCC-stripped FBS, trastuzumab induced of cell cycle arrest in G0/G1 phase in the cells and had additive effect on the radiosensitivity. If trastuzumab be able to have an influence on cell cycle, trastuzumab plus irradiation may be effective for the treatment of breast cancer with HER2 overexpression.