Reexpression of hSNF5 in malignant rhabdoid tumor cell lines causes cell cycle arrest through a p21(CIP1/WAF1)-dependent mechanism.
Reexpression of hSNF5 in malignant rhabdoid tumor cell lines causes cell cycle arrest through a p21(CIP1/WAF1)-dependent mechanism.
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DOI：
10.1158/0008-5472.can-09-1922
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发表时间：
2010-03-01
期刊：
影响因子：
11.2
通讯作者：
Weissman BE
中科院分区：
文献类型：
--
作者：
Kuwahara Y;Charboneau A;Knudsen ES;Weissman BE
hSNF5功能缺失通常在恶性横纹肌样瘤（MRT）中观察到，这是一种高度侵袭性的儿科肿瘤。先前的研究表明，hSNF5在MRT细胞系中的重表达导致G1细胞周期阻滞，其中p16INK4A、p21CIP1/WAF1和cyclin D1在MRT细胞生长控制中起关键作用。然而，我们已经证明，在缺乏p16INK4A表达的情况下，hSNF5的重新表达诱导细胞周期阻滞。这些结果表明，hsnf5诱导的细胞周期阻滞机制与环境有关。在这里，我们利用几种MRT细胞系研究了p21CIP1/WAF1和hSNF5在调节生长中的关系。我们发现G1细胞周期阻滞伴随着p21CIP1/WAF1 mRNA和蛋白水平的增加，以及p16INK4A mRNA和蛋白的上调。染色质免疫沉淀数据证实，hSNF5在重表达后出现在p21CIP1/WAF1和p16INK4A启动子上。我们进一步发现p21CIP1/WAF1诱导显示了p53依赖和独立的机制。我们还证明，通过RNAi降低p21CIP1/WAF1的表达可显著抑制hsnf5诱导的G1阻滞。我们的研究结果表明p21CIP1/WAF1和p16INK4A都是hSNF5的靶点，并且在hSNF5诱导的G1停滞期间，p21CIP1/WAF1的上调早于p16INK4A的上调。这些发现表明，SNF5介导了一个暂时受控的CDK抑制程序，以限制MRT细胞的异常增殖。
Loss of hSNF5 function is usually observed in malignant rhabdoid tumor (MRT), a highly aggressive pediatric neoplasm. Previous studies have shown that reexpression of hSNF5 in MRT cell lines causes G1 cell cycle arrest with p16INK4A, p21CIP1/WAF1 and cyclin D1 playing key roles in MRT cell growth control. However, we have shown that reexpression of hSNF5 induced cell cycle arrest in the absence of p16INK4A expression. These results indicate that the mechanism of hSNF5-induced cell cycle arrest is context dependent. Here, we investigated the relationship between p21CIP1/WAF1 and hSNF5 in the regulation of growth using several MRT cell lines. We found that G1 cell cycle arrest occurred concomitant with an increase in p21CIP1/WAF1 mRNA and protein levels and preceeded p16INK4A mRNA and protein up-regulation. Chromatin immunoprecipitation data confirmed that hSNF5 appeared at both p21CIP1/WAF1 and p16INK4A promoters after reexpression. We further showed that p21CIP1/WAF1 induction showed both p53 dependent and independent mechanisms. We also demonstrated that reduction of p21CIP1/WAF1 expression by RNAi significantly inhibited hSNF5-induced G1 arrest. Our results demonstrate that both p21CIP1/WAF1 and p16INK4A are targets for hSNF5, and that p21CIP1/WAF1 up-regulation during hSNF5-induced G1 arrest precedes p16INK4A up-regulation. These findings indicate that SNF5 mediates a temporally controlled program of CDK inhibition to restrict aberrant proliferation in MRT cells.