Genomic and functional characterizations of phosphodiesterase subtype 4D in human cancers
Genomic and functional characterizations of phosphodiesterase subtype 4D in human cancers
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DOI：
10.1073/pnas.1218206110
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发表时间：
2013-04-09
影响因子：
11.1
通讯作者：
Koeffler, H. Philip
中科院分区：
文献类型：
--
作者：
Lin, De-Chen;Xu, Liang;Koeffler, H. Philip
通过询问基因组剂量来发现癌症基因是癌症研究的主要途径之一。在本研究中，我们报告了5,569例原发实体瘤中的198例(3.56%)PDE4D基因纯合性缺失，其中大部分为内部微缺失。出乎意料的是，这些微缺失并没有导致他们的基因产物丢失。免疫组织化学染色检测11例不同类型原发肿瘤组织(n=165)中PDE4D的表达，发现其蛋白表达水平较相应的未转化组织上调。重要的是，去除内源性PDE4D和三个独立的shRNA导致多种类型的癌细胞凋亡和生长抑制，包括乳腺、肺、卵巢、子宫内膜、胃和黑色素瘤，这可以通过重新表达PDE4D来挽救。我们进一步表明，由PDE4D抑制触发的抗肿瘤事件与细胞死亡(BIM)诱导的Bcl-2相互作用介质和小眼球相关转录因子(MITF)下调具有谱系依赖性。此外，PDE4D短亚型PDE4D2的异位表达在体外和体内都促进了癌细胞的增殖。此外，用一种独特的特异性PDE4D抑制剂268治疗癌细胞时，会引发大量细胞死亡和生长迟缓。值得注意的是，这些由shRNA或小分子诱导的抗肿瘤作用优先发生在癌细胞中，而不是在非恶性上皮细胞中。这些结果表明，尽管以基因组纯合子微缺失为靶点，PDE4D仍具有肿瘤促进因子的功能，并代表了一种独特的肿瘤细胞靶向性酶。
Discovery of cancer genes through interrogation of genomic dosage is one of the major approaches in cancer research. In this study, we report that phosphodiesterase subtype 4D (PDE4D) gene was homozygously deleted in 198 cases of 5,569 primary solid tumors (3.56%), with most being internal microdeletions. Unexpectedly, the microdeletions did not result in loss of their gene products. Screening PDE4D expression in 11 different types of primary tumor samples (n = 165) with immunohistochemistry staining revealed that its protein levels were up-regulated compared with corresponding non-transformed tissues. Importantly, depletion of endogenous PDE4D with three independent shRNAs caused apoptosis and growth inhibition in multiple types of cancer cells, including breast, lung, ovary, endometrium, gastric, and melanoma, which could be rescued by reexpression of PDE4D. We further showed that antitumor events triggered by PDE4D suppression were lineage-dependently associated with Bcl-2 interacting mediator of cell death (BIM) induction and microphthalmia-associated transcription factor (MITF) down-regulation. Furthermore, ectopic expression of the PDE4D short isoform, PDE4D2, enhanced the proliferation of cancer cells both in vitro and in vivo. Moreover, treatment of cancer cells with a unique specific PDE4D inhibitor, 268, triggered massive cell death and growth retardation. Notably, these antineoplastic effects induced by either shRNAs or small molecule occurred preferentially in cancer cells but not in nonmalignant epithelial cells. These results suggest that although targeted by genomic homozygous microdeletions, PDE4D functions as a tumor-promoting factor and represents a unique targetable enzyme of cancer cells.