Regulation of p53 expression to overcome cisplatin rsistance

P53抑癌基因产物是细胞对DNA损伤反应的重要参与者。这种反应导致Gl细胞周期停滞或通过细胞凋亡而死亡。因此，P53的状态是可以预期的。以影响细胞对DNA损伤细胞毒剂的反应。本研究旨在探讨将野生型p53基因导入人骨肉瘤细胞是否能改变细胞生长速度，增强顺铂的细胞毒作用和咖啡因的协同抗肿瘤作用。以三株人骨肉瘤细胞株OST(野生型P53等位基因)、Saos2(P53等位基因缺失)和HOS(突变型P53等位基因)为研究对象。用脂质体转染法将野生型p53表达载体分别导入骨肉瘤细胞系。与亲本细胞相比，SAOS2/P53和HOS/P53细胞的生长速度明显降低。Wst-1法检测顺铂和SY…对细胞的杀伤作用咖啡因的抗肿瘤作用更强，表明在1C50中，Saos2/P53细胞对顺铂的敏感性是Saos2细胞的两倍。咖啡因对Saos2/P53细胞株的协同抗肿瘤作用也增强。另外两个转基因细胞与它们各自的亲本细胞没有显著差异。此外，用TUNEL法分析了单独用顺铂或用顺铂加咖啡因处理的Saos2细胞和Saos2/P53细胞的凋亡事件，结果表明，与亲本Saos2细胞系相比，Saos2/P53细胞对单独用顺铂和顺铂加咖啡因的敏感性最高。OST/P53和HOS/P53细胞对单独的顺铂或顺铂加咖啡因的敏感性没有明显增加。这些结果表明，在P53基因缺失的人骨肉瘤细胞系中导入野生型P53基因，可增强顺铂的细胞毒作用和咖啡因的协同抗肿瘤作用，提示利用P53基因对P53基因异常的人骨肉瘤进行基因治疗的可能性。较少

The p53 tumor suppressor gene product is an important participant in the cellular response to DNA damage. This response results in either Gl cell cycle arrest or cell death by apoptosis. Therefore, the status of p53 can be expected. to affect the cellular response to DNA-damaging cytotoxic agents. The present study was performed to investigate whether introduction of the wild-type p53 gene into human osteosarcoma cells could change growth rates and enhance the cytocidal effect of cisplatin and the synergistic antitumor effect of caffeine. Three human osteosarcoma cell lines, OST (wild p53 alleles) , Saos2 (both p53 alleles deleted) , and HOS, (both mutant p53 alleles) were used. Wild-type p53 expression plasmid was transfected into each of the osteosarcoma cell lines by using the lipofection method. The transfected cells, Saos2/p53 and HOS/p53, showed a reduction in growth rate compared with the parent cells. WST-1 assay, performed to assess the cytocidal effect of cisplatin and the sy … More nergistic antitumor effect of caffeine, showed that Saos2/p53 cells were twice as sensitive to cisplatin alone in 1C50 than were Saos2 cells. The synergistic antitumor effect of caffeine also enhanced in the Saos2/p53 cell line. The other two transfected cells revealed no significant differences from their respective parent cells. Furthermore, TUNEL assay used to analyze apoptotic events in Saos2 cells and Saos2/p53 cells that were treated either with cisplatin alone or with cisplatin and caffeine revealed that compared with the parent Saos2 cell line, Saos2/p53 become most sensitive to cisplatin alone and to cisplatin with caffeine. OST/p53 and HOS/p53 cell lines did not show any significant increase in sensitivity to either cisplatin alone or to cisplatin with caffeine. These results demonstrate that the cytocidal effect of cisplatin and the synergistic antitumor effects of caffeine are enhanced by introduction of the wild-type p53 gene in a human osteosarcoma cell line with deleted p53 alleles, indicating the possibility of gene therapy using the p53 gene for human osteosarcomas with abnormal p53 status. Less