目的：许多神经母细胞瘤细胞系及肿瘤组织标本中caspase-8表达缺失, caspase-8基因沉寂的主要原因是其启动子区域高度甲基化。该文探讨去甲基化药物5-氮杂胞苷对caspase-8表达及对化疗药阿霉素抗人神经母细胞瘤细胞作用的影响及其影响机制。方法：应用RT-PCR方法检测5-氮杂胞苷作用前后SH-SY5Y细胞中caspase-8 mRNＡ水平变化。MTT分析研究5-氮杂胞苷与化疗药阿霉素联合应用前后人神经母细胞瘤细胞SH-SY5Y的存活率，以及加入caspase-8活性抑制剂后存活率的变化。结果：RT-PCR方法发现SH-SY5Y细胞株不表达caspase-8 mRNA, 5-氮杂胞苷作用3 d后可检测到 caspase-8 mRNA表达，5 d后表达较第3天增加; 5-氮杂胞苷与不同浓度阿霉素(0.05， 0.1， 0.25， 0.5 μg/mL)联合应用后SH-SY5Y细胞存活率为(77.61±7.30)%，（57.35±6.64）%，（46.25±4.46）%，（35.59±5.12）%，同一浓度单独应用阿霉素组细胞存活率为（94.89±4.15）%，（80.60±8.50）%，（64.48±4.92）%，（52.32±6.71）%，5-氮杂胞苷与阿霉素联用组细胞存活率明显低于单用阿霉素组，差异均有显著性。Caspase-8抑制剂组与同一浓度的5-氮杂胞苷+阿霉素组比较，细胞存活率明显增加，依次为（92.95±3.48）%，（78.39±4.28）%，（62.31±6.50）%，（49.92±5.77）%，差异均有显著性。结论：阿霉素对神经母细胞瘤细胞SH-SY5Y具有增殖抑制作用，5-氮杂胞苷可以增强阿霉素的抗瘤活性。其发生机制可能是通过上调caspase-8 mRNA的表达而实现的。［中国当代儿科杂志，2007，9（6）：577-579］

OBJECTIVE: The loss of casepase-8 expression correlates with unfavorable survival outcomes in neuroblastoma (NB). Casepase-8 gene inactivation is caused by methylation. This study aimed to explore the effect of the demethylation agent 5-azacytidine on casepase-8 expression and whether 5-azacytidine can increase the sensitivity of chemotherapy drug doxorubicin to NB cells. METHODS: Caspase-8 mRNA expression in NB cell lines (SH-SY5Y cells) was examined by RT-PCR before and after 5-azacytidine treatment. Survival rates of SH-SY5Y cells were detected using MTT analysis and compared among the doxorubicin alone treatment, 5-azacytidine along with doxorubicin treatment, and caspase-8 inhibitor+5-azacytidine+doxorubicin treatment groups. RESULTS: Caspase-8 mRNA was not expressed in untreated SH-SY5Y cell lines. Caspase-8 mRNA expression in SH-SY5Y cells was detectable 3 days after 5-azacytidine treatment, and increased significantly 5 days after 5-azacytidine treatment (P<0.05). Survival rates of SH-SY5Y cells treated with 5-azacytidine along with different concentrations of doxorubicin (0.05, 0.1,0.25, 0.5 μg/mL) were (77.61±7.30)%, (57.35±6.64)%, (46.25±4.46)% and (35.59±5.12)%, respectively, which were significantly lower than those treated with doxorubicin alone (94.89±4.15%, 80.60±8.50%, 64.48±4.92% and 52.32±6.71%) (P<0.01). Caspase-8 inhibitor pretreatment resulted in an increased survival rate of SH-SY5Y cells (92.95±3.48%, 78.39±4.28 %, 62.31±6.50% and 49.92±5.77%)compared with the 5-azacytidine+doxorubicin treatment group. CONCLUSIONS: 5-azacytidine may enhance anti-tumor efficacy of doxorubicin to NB cell lines, possibly through an up-regulation of caspase-8 mRNA expression.［Chin J Contemp Pediatr, 2007, 9 (6):577-579］