Objective: To observe the platinum drugs resistance effect of N-acetyltransferase 10 (NAT10) overexpression in breast cancer cell line and elucidate the underlining mechanisms. Methods: The experiment was divided into wild-type (MCF-7 wild-type cells without any treatment) group, NAT10 overexpression group (H-NAT10 plasmid transfected into MCF-7 cells) and NAT10 knockdown group (SH-NAT10 plasmid transfected into MCF-7 cells). The invasion was detected by Transwell array, the interaction between NAT10 and PARP1 was detected by co-immunoprecipitation. The impact of NAT10 overexpression or knockdown on the acetylation level of PARP1 and its half-life was also determined. Immunostaining and IP array were used to detect the recruitment of DNA damage repair protein by acetylated PARP1. Flow cytometry was used to detect the cell apoptosis. Results: Transwell invasion assay showed that the number of cell invasion was 483.00±46.90 in the NAT10 overexpression group, 469.00±40.50 in the NAT10 knockdown group, and 445.00±35.50 in the MCF-7 wild-type cells, and the differences were not statistically significant (P>0.05). In the presence of 10 μmol/L oxaliplatin, the number of cell invasion was 502.00±45.60 in the NAT10 overexpression group and 105.00±20.50 in the NAT10 knockdown group, both statistically significant (P<0.05) compared with 219.00±31.50 in wild-type cells. In the presence of 10 μmol/L oxaliplatin, NAT10 overexpression enhanced the binding of PARP1 to NAT10 compared with wild-type cells, whereas the use of the NAT10 inhibitor Remodelin inhibited the mutual binding of the two. Overexpression of NAT10 induced PARP1 acetylation followed by increased PARP1 binding to XRCC1, and knockdown of NAT10 expression reduced PARP1 binding to XRCC1. Overexpression of NAT10 enhanced PARP1 binding to LIG3, while knockdown of NAT10 expression decreased PARP1 binding to LIG3. In 10 μmol/L oxaliplatin-treated cells, the γH2AX expression level was 0.38±0.02 in NAT10 overexpressing cells and 1.36±0.15 in NAT10 knockdown cells, both statistically significant (P<0.05) compared with 1.00±0.00 in wild-type cells. In 10 μmol/L oxaliplatin treated cells, the apoptosis rate was (6.54±0.68)% in the NAT10 overexpression group and (12.98±2.54)% in the NAT10 knockdown group, both of which were statistically significant (P<0.05) compared with (9.67±0.37)% in wild-type cells. Conclusion: NAT10 overexpression enhances the binding of NAT10 to PARP1 and promotes the acetylation of PARP1, which in turn prolongs the half-life of PARP1, thus enhancing PARP1 recruitment of DNA damage repair related proteins to the damage sites, promoting DNA damage repair and ultimately the survival of breast cancer cells.
目的： 探讨在乳腺癌细胞中高表达的N-乙酰转移酶10(NAT10)引起对铂类抗肿瘤药的耐药效应，并揭示其潜在机制。 方法： 实验分为野生型组(MCF-7野生型细胞未经任何处理)、NAT10过表达组(h-NAT10质粒转染至MCF-7细胞)和NAT10敲低组(sh-NAT10质粒转染至MCF-7细胞)。采用Transwell实验检测各组细胞的侵袭能力，采用免疫共沉淀实验检测NAT10与多聚ADP核糖转移酶1(PARP1)的相互作用，并检测过表达或敲低NAT10的表达对PARP1乙酰化水平和半衰期的影响，通过免疫组化染色和免疫沉淀实验检测乙酰化的PARP1招募相关DNA损伤修复相关蛋白的情况，采用流式细胞术检测细胞凋亡情况。 结果： Transwell实验显示，NAT10过表达组细胞侵袭数为(483.00±46.90)个，NAT10敲低组细胞侵袭数为(469.00±40.50)个，与MCF-7野生型细胞[(445.00±35.50)个]比较，差异均无统计学意义(均P>0.05)。在10 μmol/L奥沙利铂作用下，NAT10过表达组细胞侵袭数为(502.00±45.60)个，NAT10敲低组细胞侵袭数为(105.00±20.50)个，与野生型细胞[(219.00±31.50)个]比较，差异均有统计学意义(均P<0.05)。在10 μmol/L奥沙利铂作用下，与野生型细胞比较，NAT10过表达可以增强PARP1与NAT10的结合，而使用NAT10抑制剂Remodelin则抑制了二者的相互结合。高表达NAT10诱导PARP1乙酰化后，PARP1与X射线修复交叉互补蛋白1(XRCC1)的结合增加，敲低NAT10的表达后，降低了PARP1和XRCC1的结合。高表达NAT10增强了PARP1与DNA连接酶3(LIG3)的结合，而敲低NAT10的表达则会降低PARP1与LIG3的结合。在10 μmol/L奥沙利铂处理后的细胞中，NAT10过表达细胞中γH2AX表达水平为0.38±0.02, NAT10敲低细胞中γH2AX表达水平为1.36±0.15，与野生型细胞(1.00±0.00)比较，差异均有统计学意义(均P<0.05)。在10 μmol/L奥沙利铂处理后的细胞中，NAT10过表达组细胞凋亡率为(6.54±0.68)%，NAT10敲低组细胞凋亡率为(12.98±2.54)%，与野生型细胞[(9.67±0.37)%]比较，差异均有统计学意义(均P<0.05)。 结论： NAT10高表达增强了NAT10与PARP1的结合，并促进PARP1的乙酰化，进而延长了PARP1的半衰期，从而增强PARP1招募DNA损伤修复相关蛋白到损伤位点，促进DNA损伤修复，最终使乳腺癌细胞存活。.
Keywords: Breast neoplasms; N-acetyltransferase 10; PARP1.