D'Assoro Antonino B, Busby Robert, Suino Kelly, Delva Emmanuella, Almodovar-Mercado Gustavo J, Johnson Heidi, Folk Christopher, Farrugia Daniel J, Vasile Vlad, Stivala Franca, Salisbury Jeffrey L
Tumor Biology Program, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
Oncogene. 2004 May 20;23(23):4068-75. doi: 10.1038/sj.onc.1207568.
Centrosome amplification plays a key role in the origin of chromosomal instability during cancer development and progression. In this study, breast cancer cell lines with different p53 backgrounds were used to investigate the relationship between genotoxic stress, G(1)/S cell cycle checkpoint integrity, and the development of centrosome amplification. Introduction of DNA damage in the MCF-7 cell line by treatment with hydroxyurea (HU) or daunorubicin (DR) resulted in the arrest of both G(1)/S cell cycle progression and centriole duplication. In these cells, which carry functional p53, HU treatment also led to nuclear accumulation of p53 and p21(WAF1), retinoblastoma hypophosphorylation, and downregulation of cyclin A. MCF-7 cells carrying a recombinant dominant-negative p53 mutant (vMCF-7(DNp53)) exhibited a shortened G(1) phase of the cell cycle and retained a normal centrosome phenotype. However, these cells developed amplified centrosomes following HU treatment. The MDA-MB 231 cell line, which carries mutant p53 at both alleles, showed amplified centrosomes at the outset, and developed a hyperamplified centrosome phenotype following HU treatment. In cells carrying defective p53, the development of centrosome amplification also occurred following treatment with another DNA damaging agent, DR. Taken together, these findings demonstrate that loss of p53 function alone is not sufficient to drive centrosome amplification, but plays a critical role in this process following DNA damage through abrogation of the G(1)/S cell cycle checkpoint. Furthermore, these studies have important clinical implications because they suggest that breast cancers with compromised p53 function may develop centrosome amplification and consequent chromosomal instability following treatment with genotoxic anticancer drugs.
中心体扩增在癌症发生发展过程中染色体不稳定性的起源中起着关键作用。在本研究中，使用具有不同p53背景的乳腺癌细胞系来研究基因毒性应激、G(1)/S细胞周期检查点完整性与中心体扩增发展之间的关系。用羟基脲（HU）或柔红霉素（DR）处理MCF-7细胞系导致DNA损伤，从而使G(1)/S细胞周期进程和中心粒复制均停滞。在这些携带功能性p53的细胞中，HU处理还导致p53和p21(WAF1)的核积累、视网膜母细胞瘤蛋白低磷酸化以及细胞周期蛋白A的下调。携带重组显性负性p53突变体（vMCF-7(DNp53)）的MCF-7细胞表现出细胞周期G(1)期缩短，并保持正常的中心体表型。然而，这些细胞在HU处理后出现了中心体扩增。MDA-MB 231细胞系两个等位基因均携带突变型p53，一开始就表现出中心体扩增，在HU处理后出现超扩增的中心体表型。在携带缺陷型p53的细胞中，用另一种DNA损伤剂DR处理后也出现了中心体扩增。综上所述，这些发现表明，单独的p53功能丧失不足以驱动中心体扩增，但在DNA损伤后通过废除G(1)/S细胞周期检查点在这一过程中起关键作用。此外，这些研究具有重要的临床意义，因为它们表明p53功能受损的乳腺癌在用基因毒性抗癌药物治疗后可能会出现中心体扩增及随之而来的染色体不稳定性。
