Molecular mechanism of endometrial cancer and its application to gene diagnosis

1.子宫内膜癌抑制基因定位：位于染色体1q上的该基因具有诱导子宫内膜癌细胞衰老的作用。通过将引起约63 cM间质缺失的del 1q染色体或源自1q染色体的亚染色体可转移片段导入子宫内膜癌细胞，我们确定了靶基因在1q31-ter内的定位。此外，我们还对60例子宫内膜癌标本进行了1q上的杂合性缺失分析，并用1q42.2缩小了定位范围。内质网对RAS介导的转化的贡献。突变的K-ras蛋白具有诱导转录因子ER蛋白表达的能力(3倍)。ER活性增强的重组细胞是致瘤细胞，而ER活性较低的重组细胞是非致瘤细胞。抑制ER活性导致突变k-ras转化细胞的致瘤性丧失。子宫内膜癌中DPC4和DOC基因18q杂合性缺失的研究：18qLOH在子宫内膜癌中常见。通过绘制18q上的详细缺失图谱，我们发现缺失针对DPC4和DOC基因。其余等位基因中DPC4启动子区域的突变导致DPC4基因活性的抑制。反过来，DOC基因的转导抑制了子宫内膜癌细胞的致瘤性或诱导了细胞的凋亡。DOC基因通过诱导子宫内膜细胞的凋亡而发挥抑癌基因的作用。P53依赖的细胞周期蛋白G的作用：DOX诱导P53积聚、p21和细胞周期蛋白G转录，导致细胞G2/M期停滞。反过来，NAB诱导p53积聚和p21转录，但不诱导细胞周期蛋白G转录，从而导致细胞G1期停滞。细胞周期蛋白G的表达抑制相当于细胞从G2/M期中释放出来，细胞周期蛋白G的过度表达逆转了细胞对凋亡的敏感性。

1. Identification of an endometrial cancer suppressor gene locus : The gene located chromosome 1q has an ability to induce senescence in endometrial cancer cells. By introducing a del 1q chromosome that has incurred an interstitial deletion of approximately 63 cM or subchromosomal transferable fragments derived from the 1q into the endometrial cancer cells, we identified the localization of a target gene within 1q31-ter. In addition, we analyzed LOH on 1q using 60 sample of endometrial cancers and narrowed down the localization with 1q42.2. Contribution of ER to Ras mediated transformation. Mutant K-ras protein had an ability to induce expression of ER protein (3-fold) that functioned as a transcription factor. Reconstituted cells that had enhanced ER activities were tumorigenic but the cells with lower ER activities were nontumorigenic. Suppression of ER activities resulted in the loss of tumorigenicity in the cells transformed by mutant k-ras.3. Both DPC4 and DOC genes targeted by 18q LOH in endometrial cancers. : 18qLOH is frequent in endometrial cancers. By making a detailed deletions map on 18q, we found that deletions targeted both DPC4 and DOC genes. Mutations of the DPC4 promoter regions in the remaining allele resulted in the suppression of DPC4 gene activities. In turn, transfection of DOC cDNA resulted in the suppression of tumorigenicity or the induction of apoptosis in endometrial cancer cells. A DOC gene functions as a tumor suppressor gene by inducing apoptosis of endometrial cells.4. Function of p53-dependent cyclin G : Dox treatment induced p53 accumulation, p21 and cyclin G transcription, that resulted in G2/M arrest of cells. In turn, NaB induced p53 accumulation and p21 transcription but not cyclin G transcription, that resulted in G1 arrest of cells. Suppression of cyclin G expression corresponded to the release of cells from G2/M. Overexpression of cyclin G reverted the cell susceptible to apoptosis.