Co-deleting Pten with Rb in retinal progenitor cells in mice results in fully penetrant bilateral retinoblastomas.
Co-deleting Pten with Rb in retinal progenitor cells in mice results in fully penetrant bilateral retinoblastomas.
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DOI：
10.1186/s12943-015-0360-y
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发表时间：
2015-04-24
期刊：
影响因子：
37.3
通讯作者：
Hallstrom TC
中科院分区：
文献类型：
--
作者：
Xie C;Lu H;Nomura A;Hanse EA;Forster CL;Parker JB;Linden MA;Karasch C;Hallstrom TC
Rb1是儿童癌性视网膜母细胞瘤中最常发生突变的基因，其缺失导致E2F转录因子诱导增殖相关基因。然而，pRB丢失后的高E2F水平也会诱导促凋亡基因作为抑制新发肿瘤的保护机制。虽然p53积累和诱导凋亡被认为是消除E2F活性过剩细胞的主要机制，但p53缺失并不抑制RB/E2F诱导的视网膜细胞凋亡。这促使我们在体内测试PTEN/PI3K/AKT信号通路对RB/E2F细胞凋亡的抑制作用，以确定PI3K通路是否可能为视网膜母细胞瘤治疗提供潜在途径。我们建立了一个小鼠模型，使用Chx10-Cre有条件地从视网膜祖细胞中删除Rb1和Pten，而Rbl1 （p107）则是组成性地删除。通过在体内电穿孔进入新生视网膜，分别测试了途径成分对细胞凋亡和肿瘤起始的影响。采用免疫组化（IHC）方法分析小鼠视网膜组织的增殖、凋亡和通路激活情况。体外研究shrna对细胞凋亡和基因表达的影响。在小鼠视网膜祖细胞（RPCs）中，Pten与Rb1和Rbl1共删除可在30天内引起完全渗透的双侧视网膜母细胞瘤，并强烈抑制Rb/ e2f诱导的细胞凋亡。在体内将组成活性(ca)-Pik3ca、ca- akt或显性阴性(dn)-Foxo1电穿孔至具有Rb/p107缺失的易发生细胞凋亡的新生小鼠视网膜，可消除Rb/E2F诱导的细胞凋亡并诱导视网膜母细胞瘤的出现。视网膜Pten缺失激活早期视网膜母细胞瘤中p-AKT和p-FOXO1信号通路。针对Akt磷酸化靶点的无偏shRNA筛选发现，FOXOs是Rb/E2F诱导细胞凋亡以及Bim和p73促凋亡基因表达的关键介质。这些数据表明，我们确定了一个关键的分子触发器，涉及E2F/FOXO功能，以控制视网膜祖细胞稳态和视网膜母细胞瘤肿瘤的发生。考虑到RB/E2F和PTEN/PI3K/AKT通路在各种正常和恶性环境中的高频率共改变信号，我们预计我们的研究结果可以为其他祖细胞的增殖提供背景理解。本文的在线版本（doi:10.1186/s12943-015-0360-y）包含补充材料，仅供授权用户使用。
Rb1 is the most frequently mutated gene in the pediatric cancer retinoblastoma, and its loss causes E2F transcription factors to induce proliferation related genes. However, high E2F levels following pRB loss also induce apoptosis-promoting genes as a safeguard mechanism to suppress emergent tumors. Although p53 accumulation and apoptosis induction is believed to be a primary mechanism to eliminate cells with excess E2F activity, p53 deletion doesn’t suppress RB/E2F induced apoptosis in vivo in the retina. This prompted us to test the PTEN/PI3K/AKT signaling pathway on RB/E2F apoptosis suppression in vivo, to ascertain if the PI3K pathway may provide a potential avenue for retinoblastoma therapy. We developed a mouse model in which Rb1 and Pten were conditionally deleted from retinal progenitor cells using Chx10-Cre, whereas Rbl1 (p107) was constitutively deleted. Pathway components were also tested individually by in vivo electroporation into newborn retinas for an effect on apoptosis and tumor initiation. Mouse retinal tissues were analyzed by immunohistochemistry (IHC) for proliferation, apoptosis, and pathway activation. ShRNAs were used in vitro to assess effects on apoptosis and gene expression. Co-deleting Pten with Rb1 and Rbl1 in mouse retinal progenitor cells (RPCs) causes fully penetrant bilateral retinoblastomas by 30 days and strongly suppresses Rb/E2F-induced apoptosis. In vivo electroporation of constitutively active (ca)-Pik3ca, ca-Akt, or dominant-negative (dn)-Foxo1 into apoptosis prone newborn murine retina with deleted Rb/p107 eliminate Rb/E2F induced apoptosis and induce retinoblastoma emergence. Retinal deletion of Pten activates p-AKT and p-FOXO1 signaling in incipient retinoblastoma. An unbiased shRNA screen focusing on Akt phosphorylation targets identified FOXOs as critical mediators of Rb/E2F induced apoptosis and expression of Bim and p73 pro-apoptotic genes. These data indicate that we defined a key molecular trigger involving E2F/FOXO functioning to control retinal progenitor cell homeostasis and retinoblastoma tumor initiation. We anticipate that our findings could provide contextual understanding of the proliferation of other progenitor cells, considering the high frequency of co-altered signaling from RB/E2F and PTEN/PI3K/AKT pathways in a wide variety of normal and malignant settings. The online version of this article (doi:10.1186/s12943-015-0360-y) contains supplementary material, which is available to authorized users.
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影响因子：
64.5
作者：
Brunet, A;Bonni, A;Greenberg, ME
通讯作者：
Greenberg, ME
影响因子：
50.3
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