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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.

我们以前建立了三个行RET癌基因转基因小鼠。在所有这三种转基因小鼠中，皮肤黑变病在出生后不久就发生了。在衰老过程中，304和192系发生了黑素细胞肿瘤，但242系没有发生。与C57 BL反复杂交的品系304（品系304/B6）也发生了恶性皮肤黑素瘤，但品系192未发生。利用这些转基因小鼠系，我们分析了紫外线照射介导的皮肤恶性黑色素瘤的诱导机制。用紫外线反复照射192系转基因小鼠皮肤7个月，出现恶性黑色素瘤。然而，紫外线照射242系转基因小鼠，没有诱导黑素细胞肿瘤的发展。结果提示，紫外线照射影响肿瘤由良性向恶性转化的步骤，而不影响肿瘤的初始发展步骤。然后，我们表明，紫外线照射RET转基因小鼠或携带RET癌基因的NIH 3 T3细胞诱导RET激酶的激活。然后研究了紫外线照射激活RET激酶的机制。制备其中激酶结构域中的每个保守半胱氨酸残基被丙氨酸取代的突变RET，并测量增强这些突变RET活性所需的催化活性和对紫外线照射的反应性水平。我们在这项研究中发现，通过氧化保守的半胱氨酸残基（c-RET的Cys-987）的结构修饰导致RET抗原的二聚化或聚合，这伴随着RET催化活性的增加。从这些结果推测，紫外线照射，这是长期以来已知的损伤DNA和膜脂质，也影响蛋白质的结构和功能的修改，这一机制在良性黑色素细胞肿瘤恶性黑色素瘤的促进作用。