人支气管源性癌中细胞周期蛋白依赖性激酶抑制剂p21waf1/cip1转录调控的变异

Variation in transcriptional regulation of cyclin dependent kinase inhibitor p21waf1/cip1 among human bronchogenic carcinomas.

作者信息

Harr Michael W, Graves Timothy G, Crawford Erin L, Warner Kristy A, Reed Cheryl A M, Willey James C

机构信息

Department of Medicine, Medical University of Ohio, 219 Health Education Building, 3055 Arlington Avenue, Toledo, OH 43614-5806, USA.

出版信息

Mol Cancer. 2005 Jul 13;4:23. doi: 10.1186/1476-4598-4-23.

DOI:10.1186/1476-4598-4-23

PMID:16014176

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1185562/

Abstract

BACKGROUND

Cell proliferation control depends in part on the carefully ordered regulation of transcription factors. The p53 homolog p73, contributes to this control by directly upregulating the cyclin dependent kinase inhibitor, p21waf1/cip1. E2F1, an inducer of cell proliferation, directly upregulates p73 and in some systems upregulates p21 directly. Because of its central role in controlling cell proliferation, upregulation of p21 has been explored as a modality for treating bronchogenic carcinoma (BC). Improved understanding of p21 transcriptional regulation will facilitate identification of BC tissues that are responsive to p21-directed therapies. Toward this goal, we investigated the role that E2F1 and p73 each play in the transcriptional regulation of p21.

RESULTS

Among BC samples (N = 21) p21 transcript abundance (TA) levels varied over two orders of magnitude with values ranging from 400 to 120,000 (in units of molecules/106 molecules beta-actin). The p21 values in many BC were high compared to those observed in normal bronchial epithelial cells (BEC) (N = 18). Among all BC samples, there was no correlation between E2F1 and p21 TA but there was positive correlation between E2F1 and p73alpha (p < 0.001) TA. Among BC cell lines with inactivated p53 and wild type p73 (N = 7) there was positive correlation between p73alpha and p21 TA (p < 0.05). Additionally, in a BC cell line in which both p53 and p73 were inactivated (H1155), E2F1 TA level was high (50,000), but p21 TA level was low (470). Transiently expressed exogenous p73alpha in the BC cell line Calu-1, was associated with a significant (p < 0.05) 90% increase in p21 TA and a 20% reduction in E2F1 TA. siRNA mediated reduction of p73 TA in the N417 BC cell line was associated with a significant reduction in p21 TA level (p < 0.01).

CONCLUSION

p21 TA levels vary considerably among BC patients which may be attributable to 1) genetic alterations in Rb and p53 and 2) variation in TA levels of upstream transcription factors E2F1 and p73. Here we provide evidence that p73 upregulates p21 TA in BC tissues and upregulated p21 TA may result from E2F1 upregulation of p73 but not from E2F1 directly.

摘要

背景

细胞增殖控制部分依赖于转录因子的精确有序调控。p53 同源物 p73 通过直接上调细胞周期蛋白依赖性激酶抑制剂 p21waf1/cip1 来参与这一调控。E2F1 是一种细胞增殖诱导剂，它直接上调 p73，并且在某些系统中还直接上调 p21。由于 p21 在控制细胞增殖中起着核心作用，因此上调 p21 已被探索作为治疗支气管源性癌（BC）的一种方式。对 p21 转录调控的深入理解将有助于识别对 p21 导向疗法有反应的 BC 组织。为了实现这一目标，我们研究了 E2F1 和 p73 在 p21 转录调控中各自所起的作用。

结果

在 BC 样本（N = 21）中，p21 转录本丰度（TA）水平变化超过两个数量级，值范围为 400 至 120,000（以分子/106 分子β-肌动蛋白为单位）。与正常支气管上皮细胞（BEC）（N = 18）中观察到的值相比，许多 BC 中的 p21 值较高。在所有 BC 样本中，E2F1 和 p21 TA 之间无相关性，但 E2F1 和 p73α（p < 0.001）TA 之间存在正相关。在 p53 失活且 p73 为野生型的 BC 细胞系（N = 7）中，p73α和 p21 TA 之间存在正相关（p < 0.05）。此外，在一个 p53 和 p73 均失活的 BC 细胞系（H1155）中，E2F1 TA 水平较高（50,000），但 p21 TA 水平较低（470）。在 BC 细胞系 Calu-1 中瞬时表达外源性 p73α，与 p21 TA 显著增加（p < 0.05）90%以及 E2F1 TA 降低 20%相关。在 N417 BC 细胞系中，siRNA 介导的 p73 TA 降低与 p21 TA 水平显著降低相关（p < 0.01）。

结论

BC 患者中 p21 TA 水平差异很大，这可能归因于 1）Rb 和 p53 的基因改变以及 2）上游转录因子 E2F1 和 p73 的 TA 水平变化。我们在此提供证据表明，p73 在 BC 组织中上调 p21 TA，并且上调的 p21 TA 可能是由于 E2F1 上调 p73 而非 E2F1 直接作用所致。