Analysis for machanisms invokved in ultraviolct B-light-induced apoptosis in cpidcrmal cells

本研究旨在分析中波紫外线(UV)诱导表皮细胞凋亡的机制。理论背景是：1)紫外线被认为是包括鳞状细胞癌(SCC)、基底细胞癌(BCC)在内的非黑色素性皮肤癌的有效致癌物，2)紫外线能有效地诱导角质形成细胞和黑素细胞等表皮细胞的凋亡。基于这些迄今可用的关于表皮细胞凋亡的知识，我们认为如果我们可以利用关于细胞凋亡的知识来操纵治疗，例如那些抗癌的治疗。因此，为了解决这一问题，我们首先关注了人工诱导黑色素瘤细胞凋亡的研究。我们以前可以发现，晚期黑色素瘤细胞强烈表达CD95配体(CD95L/APO-1L/FasL)。由于包括免疫活性细胞在内的几乎所有类型的细胞都表达CD95(前田等人，BR J Dermatol 1998；139：198-206)，黑色素瘤可能会反击免疫…通过CD95/CD95L交联物诱导E细胞凋亡。为了利用这一知识，我们首先感兴趣的是，当我们在黑色素瘤细胞上引入CD95的表达时，我们是否可以诱导表达CD95L的黑色素瘤细胞凋亡。答案是肯定的，正如我们发表的那样，CD95在表达CD95L的黑色素瘤上的异位表达导致了这些细胞的强烈凋亡。尽管上述研究清楚地表明了CD95导入CD95L+黑色素瘤细胞的可能效果，但我们应该知道黑色素瘤CD95L何时被激活。因此，我们接下来分析了患者样本中CD95L的表达，结果发现，当黑色素瘤细胞从外部(对应的大约是中层真皮)深入3.5 mm时，就能够表达CD95L(Maeda等人，J Dermatol 2001；28：499-504)。我们共同确定了通过CD95的异位表达来治疗黑色素瘤患者的未来可行策略。除了黑色素瘤，基底细胞癌(BCC)是世界上最常见的皮肤肿瘤之一。由于BCC的发病机制尚不完全清楚，我们接下来将重点放在这个问题上。因此，我们聚焦于β-连环蛋白，它是WNT-信号通路中的一个信号元件，据报道参与了结肠癌的发病机制。为了解决这个问题，我们对基底细胞癌标本进行了免疫染色，发现大约70%的基底细胞癌中观察到了β-连环蛋白的核转位，而其他皮肤病，如特应性皮炎、牛皮癣、鳞状细胞癌等非特应性皮肤病的细胞核中出现阳性信号。由于该蛋白的核转位是参与癌变的必要条件，因此我们认为b-连环蛋白参与了基底细胞癌的发病过程。需要进一步的分析来确定哪些元件是导致β-连环蛋白核转位的原因。较少

This research project was primarily designed to analyze mechanisms involved in ultraviolet B light (UV)-induced apoptosis of epidermal cells. The theoretical background was 1)UV is regarded as a potent carcinogen of non- melanomatous skin cancers, including squamous ell carcinoma (SCC), basal cell carcinoma (BCC), 2)UV is well known to effectively induce apoptosis of epidermal cells, such as keratinocytes and melanocytesl. Based on these so far available knowledge about apidermal cell apoptosis, we thought if we can use the knowlede regarding apoptosis to manipulate therapics, such as those against cancers. Therefore, to address this concern, we first focused on artificial induction of apoptosis of melanoma cells. We previously could chow that melanoma cells, in advanced stage, vigorously express CD95 ligand (CD95L/APO-1L/FasL). Since almost all types of cells including immunocompetent cells express CD95 (Maeda et al, Br J Dermatol 1998 ; 139 : 198-206), melanoma may counterattackimmun … More e cells by inducing their apoptosis via CD95/CD95L crosslinking. To employ this knowledge, we first were interested whether we could induce apoptosis of CD95L-expressing melanoma cells when we introduce expression of CD95 on melanoma cells. The answer was 'yes', as published by us that ectopic expression of CD95 on CD95L-expressing melanoma led to vigorous apoptosis of those cells. This implies future therapeutic uefulness of this strategy in melanoma thereapy.Although the above study clearly indicates the possible effectiveness of CD95 introduction of CD95L+melanoma cells, we should know when melanoma CD95L is turned on. Therefore, we next analysed using patients' specimens for expression of CD95L consequently, it was found that a melanoma cell, when reaches deeper than 3.5-mm from the outside (corresponding approximately middle dermis), becomes able to express CD95L (Maeda et al, J Dermatol 2001 ; 28 : 499-504). Together, we were able to identify the future feasible strategy to treat melanoma patients by ectopic expression of CD95.Besides melanoma, basal cell carcinoma (BCC) is one of the most frequently encountered dermatological neoplasms worldwide. Since pathegenesis of BCC is not completely clear yet, we next focused about this issue. Therefore, we focused β-catenin, a signaling element of Wnt-signaling pathway and reported to be involved in pathogenesis of colon cancers. To address this issue, we immunostained BCC specimens, revealing that nuclear translocation of β-catenin was observed in approximately 70% of BCC tested, while non of other dermatoses, such as atopic dermatitis, psoriasis, squamous cell carcinoma, gave rise to positive signal in muclei. Because nuclear translocation of this protein is a requisite condition to be involved in carcinogenesis, we concluded that b-catenin is involved in pathogenesis of BCC. Further analysis is required to identify which elements are causal to nuclear translocation of β-catenin. Less