Analysis of the mechanism of ultraviolet irradiation-mediated induction skin malignant melanoma

紫外线照射介导诱发皮肤恶性黑色素瘤的机制分析

基本信息

批准号：
12670816
负责人：
NAKASHIMA Izumi
金额：
$ 2.5万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

We previously established three lines of RET oncogene-transgenic mice. In all of these three lines of transgenic mice skin melanosis developed soon after birth. Melanocytic tumors developed in lines 304 and 192 but not in line 242 during ageing. Malignant skin melanoma also developed in line 304 which had been crossed repeatedly with C57BL (line 304/B6), but not in line 192. Using these transgenic mouse lines, we analyzed the mechanism of ultraviolet irradiation-mediated induction of skin malignant melanoma. When line 192 of transgenic mice were irradiated repeatedly with ultraviolet light for 7 months skin, malignant melanoma developed. Ultraviolet irradiation of line 242 of transgenic mice, however, did not induce the development of melanocytic tumors. These results suggested that ultraviolet irradiation affects the step of tumor promotion from benign to malignant but not the step of the initial development of tumor. We then showed that ultraviolet irradiation of either RET-transgenic mice or NIH3T3 cells that carried RET oncogene induced activation of RET kinase. The mechanism of activation of RET kinase by ultraviolet irradiation was then examined. Mutant RETs in which each of the conserved cysteine residues in the kinase domain was replaced with alanine were prepared, and the levels of catalytic activity and reactivity to ultraviolet irradiation required for augmention of the activity of these mutant RETs were measured. We found in this study that structural modification through oxidation of a conserved cysteine residue (Cys-987 of c-RET) causes dimerization or polymerization of RET antigens, which accompanies an increase in catalytic activity of RET. It was speculated from these results that ultraviolet irradiation, which is long known to injure DNA and membrane lipid, also affects proteins for modification of structure and function and this mechanism plays a role in the promotion of benign melanocytictumors to malignant melanoma.

我们以前建立了三条RET癌基因 - 转基因小鼠。在这三种三线的转基因小鼠中，皮肤黑色素病在出生后不久就出现了。黑素细胞肿瘤在第304和192行开发，但在衰老期间不在242行中。恶性皮肤黑色素瘤也在第304号线中发育而成，该第304号线与C57BL反复交叉（第304/B6行），但在第192行中不反复交叉。使用这些转基因小鼠系，我们分析了紫外线辐照介导的诱导皮肤恶性肿瘤的机制。当第192行的转基因小鼠用紫外线反复辐照7个月的皮肤时，恶性黑色素瘤就会发展出来。但是，转基因小鼠第242行的紫外线辐射并未诱导黑素细胞肿瘤的发展。这些结果表明，紫外线辐射会影响肿瘤从良性到恶性的促进的步骤，但不影响肿瘤初始发展的步骤。然后，我们证明了携带RET癌基因诱导的RET激酶激活的RET-转基因小鼠或NIH3T3细胞的紫外线照射。然后检查了通过紫外线辐射激活RET激酶的机制。突变体RET在激酶结构域中的每个保守的半胱氨酸残基被制备代替丙氨酸，并测量了增强这些突变体RET活性所需的催化活性和对紫外线辐照的反应水平。我们在这项研究中发现，通过氧化保守的半胱氨酸残基（C-987）的结构修饰会导致RET抗原的二聚化或聚合，从而伴随RET的催化活性增加。从这些结果中可以推测，紫外线辐射（长期以来已知会损害DNA和膜脂质）也会影响蛋白质的结构和功能修饰，并且这种机制在促进良性黑素细胞肿瘤对恶性黑色素瘤的促进中起作用。