Molecular genetic investigation of Japanese cutaneous melanoma

日本皮肤黑色素瘤的分子遗传学研究

基本信息

批准号：
09670868
负责人：
TAKATA Minoru
金额：
$ 1.79万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09670868/
关键词：
melanoma p16 tumor suppressor gene metastasis loss of heterozygosity chromosome microsatellites 転移抑制遺伝子第9染色体 p16

项目摘要

In a systematical analysis in 46 Japnese sporadic primary cutaneous melanomas, we detected loss of heterozygosity (LOH) of chromosome region 9p21 (where the p16 resides) in 11 (24%) tumors. Direct sequencing, however, revealed no somatic mutation of the p16 gene. Further sequencing analyses in 19 additional tumours with no evidence of LOH of 9p21 identified only one heterozygous C->T mutation at codon 81. De novo methylation of the promoter 5'CpG island of the p16 gene, which would lead to transcriptional silencing, was not demonstrated in any of these 12 tumours harboring 9p21 LOH or heterozygous p16 mutation by methylation-specific PCR assay. Nonetheless, complete loss of p16 protein, most likely due to homozygous deletion of the p16 gene, was observed in 6 (15%) out of 39 evaluable cases by immunohistochemical analyses on frozen sections. The results show that inactivation of p16 is not as frequent in primary melanoma as has been reported in cell lines, and warrant further search for another tumour suppressor on 9p21 which is likely to be more important in the initiation of melanoma. Simultaneous investigation examining corresponding metastases in 14 cases showed complete loss of p16 expression during matastatic progression in 4 cases, suggesting that inactivation of p16 plays an important role in progression (rather than initiation) of sporadic melanoma. This analysis also compared LOH of chromosome arms 6q, 9p, 9q, 10q, 11q and 18q, and provided clear evidence that in 3 cases clones of cells found in the sites of metastasis did not derive from the dominant subclone within the primary tumor, indicating that a linear model of melanoma progression is too simplistic, as there is likely to be considerable genetic heterogeneity at the earliest stages of tumourigenesis and that metastases from the same tumor may harbor different genetic change.

在46个Japnese偶发的原发性皮肤黑色素瘤中的系统分析中，我们检测到染色体区域9p21（p16居住）在11（24％）肿瘤中的杂合性丧失（LOH）。然而，直接测序显示没有p16基因的体细胞突变。 Further sequencing analyses in 19 additional tumours with no evidence of LOH of 9p21 identified only one heterozygous C->T mutation at codon 81. De novo methylation of the promoter 5'CpG island of the p16 gene, which would lead to transcriptional silencing, was not demonstrated in any of these 12 tumours harboring 9p21 LOH or heterozygous p16 mutation by methylation-specific PCR分析。尽管如此，在39例可评估病例中，通过对冷冻切片的免疫组织化学分析，在39例可评估病例中观察到了P16蛋白的完全损失，这很可能是由于p16基因的纯合缺失引起的。结果表明，在原发性黑色素瘤中灭活p16的频繁不如细胞系报道，并保证在9p21上进一步寻找另一个肿瘤抑制剂，这对于开始黑色素瘤的结果可能更为重要。在14例病例中检查相应转移的同时研究表明，在4例矩阵进展过程中p16表达完全丧失，这表明p16的失活在零星黑色素瘤的进展（而不是开始）中起重要作用。该分析还比较了染色体臂6q，9p，9q，9q，10q，11q和18q的LOH，并提供了明确的证据，表明在转移部位发现的3例细胞克隆并未从原发性肿瘤中的主要亚克隆中得出，表明黑素瘤的进展很简单，可能是属性的，并且可能是属性的，并且属性是有效的。来自同一肿瘤的转移可能具有不同的遗传变化。