Reseearch on Genetic Alterations in the Development and Progression of Human Pancreatic Cancer

分析胰腺癌中6个常丢失区域的不良预后与洛之间的关系;在3个区域（12 q、17 p和18 q）中有显著相关性。其中，18 q携带SMAD 4，这是胰腺癌发生的关键基因之一。IPMT被认为是胰腺导管细胞的癌前病变之一，并且已经观察到SMAD 4位点的18 q频繁丢失。SMAD 4蛋白表达量与对照组相比无显著性差异。SMAD 4的引入不影响细胞在体外的生长，无论SMAD 4的状态。另一方面，在SMAD 4失活和未失活的细胞中，染色体18的引入显著抑制了体外细胞生长。这些观察结果强烈表明，存在新的肿瘤抑制基因，接近但不同于SMAD 4，在胰腺肿瘤发生的早期阶段起着重要作用。在12 q上，我们发现了DUSP 6基因，其蛋白产物作为ERK特异性磷酸酶起作用。该基因的表达在胰腺癌中经常被抑制，腺病毒介导的导入引起胰腺癌细胞凋亡。BAI 1是p53上调的重要蛋白之一。它作为血管生成抑制剂，在脑中特异性表达。我们使用腺病毒载体在胰腺癌细胞中引入BAI 1，并通过抑制血管生成观察体内生长抑制;有可能利用肿瘤休眠进行基因治疗。1 p36-p35是人类多种肿瘤中洛丢失的热点之一。我们在该区域构建了一个35-Mb的基于BAC的重叠群。编码RB相互作用锌指蛋白的RIZ基因位于该区域，突变分析显示在结直肠、胃、子宫内膜和胰腺的MSI-H肿瘤中该基因编码区的微卫星处频繁发生移码突变。RIZ可能是MSI-H胰腺癌突变的候选基因之一。

Six frequently lost regions in pancreatic cancer were analyzed for association between poor prognosis and LOH ; in three regions (12q, 17p, and 18q) significant association. Among these, 18q harbors SMAD4, one of the key genes in pancreatic carcinogenesis. IPMT is recognized as one of the premalignant lesions of pancreatic ductal cells, and frequent loss of 18q at the SMAD4 locus has been observed. However, SMAD4 did not alter and its protein product expressed. Introduction of SMAD4 did not affect cell growth in vitro, irrespective of SMAD4 status. On the other hand, introduction of chromosome 18 significantly suppressed cell growth in vitro in both cells with and without inactivation of SMAD4. These observations strongly suggest the existence of novel tumor suppressor gene, near but distinct from SMAD4, that plays an important role in the early stage of pancreatic tumorigenesis. On 12q, we found the DUSP6 gene, the protein product of which works as an ERK specific phosphatase. Expression of this gene was frequently suppressed in pancreatic cancer, and adenovirus mediated introduction caused apoptosis in pancreatic cancer cells. BAI1 is one of the important protein that upregulated by p53. It works as angiogenesis inhibitor and expresses specifically in brain. We introduced BAI1 in pancreatic cancer cells using adenovirus vector and observed growth suppression in vivo by means of suppressed angiogenesis; there is a possibility of gene therapy utilizing tumor dormancy. 1p36-p35 is one of the hot spots for LOH in a variety of human cancers. We constructed a 35-Mb BAC-based contig in this region. The RIZ gene encoding the RB interacting zinc finger protein was in this region and mutation analysis revealed the frequent frameshift mutation at the microsatellite in the coding region of the gene in MSI-H tumors of the colorectum, stomach, and endometrium as well as pancreas. RIZ may be one of the candidates for mutation in MSI-H pancreatic cancers.