Analysis of the Novel Tumor Suppressor Gene SNF5/INI1

描述（由申请人提供）： 恶性横纹肌样瘤（MRT）是一种 侵袭性的、高致命性的癌症，侵袭幼儿。 肿瘤发生在 包括肾、脑和软组织的各种位置。 尽管 强化治疗，80%的受影响儿童死亡，通常在1年内， 诊断. 绝大多数MRT具有持续的双等位基因失活， hSNF 5/INI 1基因的突变，表明SNF 5可能作为肿瘤 抑制器。 支持这一观点的事实是，15%的儿童 MRT在SNF 5的一个等位基因中存在体细胞突变， 在肿瘤中的等位基因。 SNF 5是SWI/SNF染色质的核心成员 重塑复合物，这是所需的调节表达的一个子集， 基因. 在人类中，SNF 5与HIV整合酶结合，并刺激HIV整合。 HIV进入人体DNA 研究还表明，SNF 5与EBNA、MLL/ALL结合。 1，trithorax和c-MYC，并通过这些因子刺激转录。 SWI/SNF复合物的另一个成员Brg 1直接与pRb相互作用， 是Rb介导的细胞周期阻滞所必需的。 Brg 1单倍不足 使小鼠易于形成肿瘤，Brg 1在几种乳腺癌中缺乏， 癌细胞系。 总之，这些数据表明SWI/SNF的广泛作用 肿瘤抑制 虽然很明显SNF 5和SWI/SNF参与肿瘤抑制， 染色质重塑和转录激活，它们的作用机制 这些过程之间的关系并不清楚。 我们用基因 靶向小鼠的SNF 5。 SNF 5的缺失导致胚胎 而单倍不足导致15%的小鼠发展为 肿瘤在组织学上与人MRT难以区分。 的具体目标 所提出的项目是产生SNF 5缺陷细胞，以确定 SNF 5在生长调节和致癌转化中的功能。 第二、 通过产生条件性靶向小鼠来改进MRT模型， 在人类肿瘤发生的地方发展高转移率的MRT。 第三，通过使用条件限制性内切酶来鉴定SNF 5下游基因， DNA微阵列分析中的靶细胞。 最后，为了调查 SNF 5在转录调控中的功能--通过SNF 5缺陷的分析 使用体外转录测定的细胞。 因为SNF 5是一个不变量， 亚基存在于所有SWI/SNF复合物中，阐明其功能将 提供了一个新认识的肿瘤抑制机制的见解， 可以确定新的治疗干预目标， 儿科癌症 该提案直接涉及科学优先事项 由NCI的BT-PRG部门鉴定。

DESCRIPTION (provided by applicant): Malignant rhabdoid tumor (MRT) is an aggressive, highly lethal cancer that strikes young children. Tumors occur in various locations including kidney, brain, and soft tissues. Despite intensive therapy, 80 percent of affected children die, often within 1 year of diagnosis. The vast majority of MRTs have sustained bi-allelic inactivating mutations of the hSNF5/INI1 gene, suggesting that SNF5 may act as a tumor suppressor. Supporting this idea is the fact that 15 percent of children with MRT have somatic mutations in one allele of SNF5 and loss of the remaining allele in their tumors. SNF5 is a core member of the SWI/SNF chromatin remodeling complex, which is required for regulated expression of a subset of genes. In humans, SNF5 binds to HIV integrase and stimulates integration of HIV into human DNA. Studies have also shown that SNF5 binds to EBNA, MLL/ALL- 1, trithorax, and c-MYC and stimulates transcription by these factors. Another member of the SWI/SNF complex, Brg1, directly interacts with pRb and is required for Rb mediated cell cycle arrest. Haploinsufficiency of Brg1 predisposes mice to tumor formation and Brg1 is deficient in several breast cancer cell lines. Together, these data suggest a widespread role for SWI/SNF in tumor suppression. While it is clear that SNF5 and SWI/SNF are involved in tumor suppression, chromatin remodeling and transcriptional activation, their mechanism of action and the relationship between these processes is not clear. We have used gene targeting to inactivate SNF5 in mice. Absence of SNF5 results in embryonic lethality while haploinsufficiency results in 15 percent of mice developing tumors histologically indistinguishable from human MRT. The specific aims of the proposed project are to generate SNF5 deficient cells to determine the function of SNF5 in growth regulation and oncogenic transformation. Second, to improve the MRT model by generating conditionally targeted mice that develop MRT with high penetrance in locations where human tumors occur. Third, to identify genes downstream of SNF5 through use of conditionally targeted cells in DNA micro-array analysis. Lastly, to investigate the function of SNF5 in transcriptional regulation by analysis of SNF5 deficient cells using in vitro transcriptional assays. Since SNF5 is an invariant subunit present in all SWI/SNF complexes, elucidation of its function will provide insight into a newly appreciated mechanism of tumor suppression and may identify new targets for therapeutic intervention against a lethal pediatric cancer. This proposal directly addresses scientific priorities identified by the BT-PRG arm of the NCI.