Local Immunoregulation of Carcinogenesis

描述(由申请人提供)： 皮肤癌变中肿瘤易感性的调节机制反映了皮肤的基本过程，因此，研究免疫对这些活动的贡献不仅有助于深入了解皮肤癌的发病机制，而且有助于了解皮肤的基本病理生理学。在DMBA(一种致突变的多芳烃)的两阶段化学致癌作用下，然后重复应用促炎症肿瘤促进剂TPA，我们观察到朗格汉斯细胞(LC)缺陷的小鼠对肿瘤形成有明显的抵抗力，我们的发现表明LC的作用被低估了-它们有可能增强PAH诱导的致癌H-RAS突变。其他人最近的工作表明，LC对多环芳烃的处理可能对皮肤病过程具有普遍意义，不仅包括与化学诱导的癌症相关的过程，还包括紫外线(UV)诱导的p53突变。因此，我们建议利用化学和紫外线诱导的角质形成细胞转化的互补系统，以及新的动物模型，来阐明免疫对皮肤肿瘤启动和促进的影响。此外，在持续暴露于刺激物、毒素和致癌物的上皮组织中，慢性炎症和癌症之间存在着无可辩驳的联系。因此，我们对两阶段癌变研究的另一个令人惊讶的发现是鉴定出促进恶性进展的CD8+T细胞亚群(T-PRO)，这一点具有重大意义。因此，我们建议：(1)利用LC缺陷(Langerin-DTA)小鼠研究LC在肿瘤启动(突变)中的作用，并研究LC和其他DC群体的诱变能力。为此，我们设计了一种新的体外诱变试验和一种新的实时荧光定量检测H-ras突变的方法。我们还将使用可诱导的NKG2D配体小鼠来研究在皮肤环境中操作的主要刺激如何影响这些对肿瘤发展至关重要的活动。(2)确定LC在促癌过程中的致癌作用。为此，我们将使用一种新的可诱导的LC缺陷(hLangerin-DTR)小鼠来耗尽施加DMBA之后但在TPA促进之前的LC。(3)确定LC在紫外线诱导的角质形成细胞反应(细胞凋亡、p53突变克隆、克隆性扩增)中的作用。我们将使用与化学致癌相同的LC缺乏的结构性和诱导性模型。(4)在描述了CD8+T-PRO与恶性进展相关的表达模式后，我们将进一步研究它们的来源、分化和治疗操作的潜力。详细阐述LC、角质形成细胞和T细胞之间的相互作用将极大地促进我们对癌症发生和基本皮肤生物学的理解；可能提供对其他上皮细胞内免疫影响的洞察；并对设计用于调节DC和/或T细胞功能的治疗方案具有重要意义。

DESCRIPTION (provided by applicant): The mechanisms regulating tumor susceptibility in cutaneous carcinogenesis reflect essential processes of the skin, and therefore investigation of immune contributions to these activities provides insight not only into the pathogenesis of skin cancer but also into basic cutaneous pathophysiology. Under two-stage chemical carcinogenesis with DMBA, a mutagenic polyaromatic hydrocarbon (PAH), followed by repeated applications of a pro-inflammatory tumor promoter, TPA, we observed that mice deficient in Langerhans cells (LC) are markedly resistant to tumor formation, and our findings have suggested an under- emphasized role of LC - their potential to enhance PAH-induced oncogenic H-Ras mutations. Recent work by others has revealed that the handling of PAHs by LC may have general implications for skin disease processes, including not only those relevant to chemically induced cancer, but also ultraviolet (UV)-induced p53 mutations. Thus, we propose to utilize the complimentary systems of chemical and UV- induced keratinocyte transformation, and novel animal models, to elucidate immune influences on cutaneous tumor initiation and promotion. Moreover, there is an irrefutable association of chronic inflammation and cancer in epithelial tissues continually exposed to irritants, toxins, and carcinogens. Thus, it is of major relevance that a further surprising finding of our studies of two-stage carcinogenesis has been the identification of a CD8+ T cell subset (T-pro) that promotes malignant progression. Thus, we propose to: (1) Investigate the role of LC in tumor initiation (mutagenesis) using the LC-deficient (Langerin-DTA) mouse, and study LC and other DC populations for their mutagenic capacity. For this, we designed a novel in vitro mutagenesis assay, and a novel real-time PCR method for the quantification of H-ras mutations. We will also use an inducible NKG2D-ligand mouse to investigate how major stimuli operative in the cutaneous environment may influence these activities so critical to tumor development. (2) Determine the contributions of LC to carcinogenesis during tumor promotion. For this we will use a new inducible LC- deficient (hLangerin-DTR) mouse to deplete LC after DMBA application, but before TPA promotion. (3) Determine the role of LC in UV-induced keratinocyte responses (apoptosis, p53 mutant clones, clonal expansion) critical to transformation. We will use the same constitutive and inducible models of LC deficiency as for chemical carcinogenesis. (4) Having recently delineated the expression pattern of CD8+ T-pro in association with malignant progression, we will further characterize their origin, differentiation, and potential for therapeutic manipulation. The elaboration of interactions between LC, keratinocytes, and T cells will substantially advance our understanding of carcinogenesis and basic skin biology; may provide insight into immune influences within other epithelia; and has implications for therapeutic regimens designed to modulate DC and/or T cell function.