HOXB13 contributes to G1/S and G2/M checkpoint controls in prostate
HOXB13 contributes to G1/S and G2/M checkpoint controls in prostate
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DOI：
10.1016/j.mce.2013.12.003
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发表时间：
2014-03-05
影响因子：
4.1
通讯作者：
Korkmaz, Kemal Sami
中科院分区：
文献类型：
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作者：
Hamid, Syed Muhammad;Cicek, Seher;Korkmaz, Kemal Sami
HOXB13是一种同源盒蛋白，在正常成人前列腺和结肠组织中表达；然而，其表达失调在多种恶性肿瘤中均有体现。为了明确HOXB13在细胞周期进程中的假定作用，我们在PC - 3和LNCaP细胞中进行了过表达及小干扰RNA（siRNA）介导的基因敲低研究。还使用来自20例根治性前列腺切除术标本的包含正常、前列腺上皮内瘤变（H - PIN）和前列腺癌（PCa）切片的福尔马林固定、石蜡包埋组织进行了免疫组织化学（IHC）分析。此外，当评估HOXB13在细胞周期进程中的作用、与细胞周期蛋白的关联、细胞生长以及使用实时细胞增殖技术分析集落形成时，我们观察到HOXB13的异位表达通过促进细胞周期蛋白D1的泛素化和降解从而降低其水平，使细胞聚集在G1期。这种减少减缓了所检测的两种细胞系进入S期的进程，同时伴有pRb（S780和S795）磷酸化水平的降低。相反，siRNA介导的HOXB13表达缺失显著增加了细胞周期蛋白水平，稳定了E2F1和CDC25C，随后pRb磷酸化水平升高。细胞周期蛋白B1和CDC25C的这种增加共同通过使CDK1（T14Y15）去磷酸化促进了细胞周期蛋白B复合物的激活，并在诺考达唑同步化后恢复了G2/M期转换。尽管通过对前列腺组织的免疫组织化学评估观察到在H - PIN和PCa样本中HOXB13的总表达水平增加且在细胞质中滞留，但HOXB13的缺失却促进了PC - 3和LNCaP细胞的增殖。因此，我们认为HOXB13的表达对于细胞周期调控是必需的，并且由于其在癌症中的功能缺失，通过一种未知机制而增加。（C）2013爱思唯尔爱尔兰有限公司。保留所有权利。
HOXB13 is a homeobox protein that is expressed in normal adult prostate and colon tissues; however, its deregulated expression was evidenced in various malignancies. To characterize the putative role of HOXB13 in cell cycle progression, we performed overexpression and siRNA-mediated knockdown studies in PC-3 and LNCaP cells. Immunohistochemistry (IHC) analyses were also performed using formalin-fixed, paraffin-embedded tissues containing normal, H-PIN and PCa sections from 20 radical prostatectomy specimens. Furthermore, when the role of HOXB13 during cell cycle progression, association with cyclins, cell growth and colony formation using real-time cell proliferation were assessed, we observed that ectopic expression of HOXB13 accumulated cells at G1 through decreasing the cyclin D1 level by promoting its ubiquitination and degradation. This loss slowed S phase entry in both cell lines examined, with an associated decrease in pRb((S780) and ()S(795)) phosphorylations. Contrary, siRNA-mediated depletion of HOXB13 expression noticeably increased cyclin levels, stabilized E2F1 and CDC25C, subsequent to increased pRb phosphorylations. This increase in Cyclin B1 and CDC25C both together facilitated activation of cyclin B complex via dephosphorylating CDK1((T14Y15)), and resumed the G2/M transition after nocodazole synchronization. Despite an increase in the total expression level and cytoplasmic retention of HOXB13 in H-PIN and PCa samples that were observed via IHC evaluation of prostate tissues, HOXB13 depletion facilitated to an increase in PC-3 and LNCaP cell proliferation. Thus, we suggest that HOXB13 expression is required for cell cycle regulation, and increases by an unknown mechanism consequent to its functional loss in cancer. (C) 2013 Elsevier Ireland Ltd. All rights reserved.