Genetic analysis for cancer risk estimation of low-dose radiation exposure.

通过基因表达和杂合性缺失(LOH)的分析，研究了辐射诱发小鼠肝癌的遗传学变化。我们利用体外建立的原发肝癌及其细胞系，得到了以下三个结果。1)利用差异显示技术，试图找出在原发性肝癌和正常肝脏中差异表达的基因。我们发现了5个过表达的基因，如ATPase抑制物、核糖体蛋白L35。纤溶酶原激活物抑制物载脂蛋白A-IV和3-羟基-3-甲基戊二酰辅酶A合成酶，以及三个低表达基因，如UDP glucuronosyltransferase-2.4-hydroxyphenylpyruvate双加氧酶。和磷脂扰乱酶在原发性肝癌中的表达。2)在肝癌细胞系中，我们发现在第4号染色体LCI位点附近存在频繁的杂合性缺失，其中C57BL小鼠等位基因丢失最多。3)在软琼脂培养的肝癌细胞中发现了两个过表达的基因。其中一个是反转录转座子VL30，即Oth…更多的是新分离的基因，命名为SDF-III，与SDF-II有同源性。VL3O在睾丸、卵巢和肾上腺中高表达。对VL3O基因在肝组织中表达的分析表明，在肝癌变过程中，VL3O基因在正常肝组织中的表达由VL3O亚组3的弱表达转变为VL3O亚组1的强表达。SDF-III蛋白的结构分析表明，该蛋白为伴侣蛋白，定位于内质网的管腔内，可能在蛋白质组装中发挥作用。我们在原发癌中发现RAD54功能区的错义突变和野生型RAD54表达的缺失，这是由异常剪接引起的。此外，我们克隆了人RALD54同源物，命名为RAD54B，并在原发淋巴瘤和结肠癌中发现了RAD54B高度保守的纯合子突变。这些发现表明，一些癌症是通过同源重组基因功能的改变而产生的。较少

Genetic changes of radiation-induced mouse hepatomas was studied by analyzing the expression of mRNA and loss of heterozygosity (LOH). We used primary hepatomas and it's cell lines established in-vitro, and got following three results. 1) We tried to identify genes differntially expressed in primary hepatomas compared to normal liver by using differetial display technique. we found five over-expressed genes such as ATPase inhibitor, ribosomal protein L35. plasminogen activator inhibitors apolipoprotein A-IV.and 3-hydroxy-3-metyylglutaryl coenzyme A (HMG-CoA)synthase, and three under-expressed genes such as UDP glucuronosyltransferase-2.4-hydroxyphenylpyruvate dioxygenase. and phospholipid scramblase in primary hepatomas. 2) In hepatoma cell lines, we found the frequent LOH around the locus of Lci on chromosome 4, where C57BL mouse allele was preferentiafly lost. 3) We identified over-expressed two genes in hepatoma cells grown in soft agar culture. one was retrotransposon VL3O, the oth … More er was newly isolated gene, designated SDF-III which had homology to SDF-II.VL3O was highly expressed in testis, ovary, and adrenal gland. Analysis of the expression of VL3O mRNA in liver revealed that the expression of VL3O mRNA had changed from the weak expression of VL3O subgroup 3 in normal livers to the strong expression of VL3O subgroup 1 in hepatomas during hepato-carcinogenesis. The structure of SDF- III protein indicated that this protein was chaperon protein which located in luminal of endplasmic reticulum, and might play a role for protein assembly.The involvement of mutations in homologus recombination genes, members of the RAD52 epistasis group, was studied in human cancer. We found missense mutations at functional regions of RAD54 and the absence of the wild-type RAD54 expression resulting from aberrant, splicing in primary cancers. Furthermore, we cloned human RALD54 homologue, designated RAD54B, and found homozygous mutations at highly conserved position of RAD54B in primary lymphoma and colon cancer. These findings suggest that some cancers arise through alterations of the homologus recombination gene function. Less