Use p105(sr) to study p50 homodimer in skin tumor/cancer

描述(申请人提供)：核因子-kappaB在肿瘤和癌症的发生中起重要作用。已经在几种类型的肿瘤和癌症中检测到具有结构性活性的核因子-kappaB。然而，与其他类型的癌症不同，核因子-kappaB异源二聚体p50/relA活性升高，化学诱导的皮肤乳头状瘤和鳞状细胞癌(SCC)表现出显著的p50同源二聚体活性升高。在皮肤肿瘤和癌症中，这种升高的原因是由p50同源二聚体调节的基因，这些基因如何在肿瘤发生和恶性肿瘤中起作用尚不清楚。SCC也因其对癌症治疗的抵抗力而闻名。将基于kappa-B-α的核因子-kappaB超抑制因子(Sr)导入癌细胞，通过DNA微阵列分析成功地分离了核因子-kappaB靶基因。通过这种方法抑制核因子-kappaB的活性也有助于肿瘤坏死因子α(TNFpha)或化疗试剂诱导癌细胞的凋亡。由于p50同源二聚体的活性不受原型kappab的调节，这种方法不能应用于皮肤肿瘤和癌症。我们在核因子-kappaB抑制剂p105的基础上开发了一种核因子-kappaB的超级抑制因子，并证明p105(Sr)广泛而有效地抑制了所有的核因子-kappaB。P105(Sr)的过表达产生p105(Sr)/p50异二聚体，从而阻止p50同源二聚体的形成。P105(Sr)/rel蛋白复合体的形成应能广泛抑制核因子-kappaB的活性。我们的长期目标是了解核因子-kappaB在肿瘤发生中的作用。我们假设致癌物TPA对皮肤的处理导致p50前体p105的周转增加，释放p50形成同源二聚体。在皮肤肿瘤中，p50同源二聚体与结构性激活的Ha-ras协同作用，在肿瘤的发生中发挥作用。将p105(Sr)导入皮肤肿瘤细胞将导致对包括p50同源二聚体调控的基因在内的核因子-kappaB调控基因的系统剖析。这种方法也将有助于促进肿瘤细胞由肿瘤坏死因子α和化疗试剂介导的凋亡。我们将研究皮肤肿瘤细胞中p50同源二聚体活性升高的机制。我们还将测试将p105(Sr)引入皮肤肿瘤细胞是否促进细胞凋亡，以及这种方法是否显著影响正常角质形成细胞的生理功能。

DESCRIPTION (provided by applicant): NF-kappaB plays a significant role in tumori- and carcinogenesis. Constitutively active NF-kappaB has been detected in several types of tumors and cancers. However, unlike other types of cancers where NF-kappaB heterodimer p50/RelA activity is elevated, chemical-induced skin papillomas and squamous cell carcinomas (SCC), exhibit significantly elevated p50 homodimer activity. The cause of this elevation in skin tumors and cancers,are the genes regulated by p50 homodimer, and how these genes contribute to tumorigenesis and malignancy are unknown. SCCs are also known for their resistance to cancer therapies. Introduction of kappa-B-alpha-based NF-kappaB super represser (sr) into cancer cells has led to successful dissection of the NF-kappaB target genes via DNA microarray analysis. Repression of NF-kappaB activities by this method also facilitates tumor necrosis factor alpha (TNFalpha)-, or chemotherapy reagents-induced apoptosis in cancer cells. Since p50 homodimer activities are not regulated by prototypic kappaBs, such approach cannot be applied to skin tumors and cancers. We have developed an NF-kappaB super represser based on NF-kappaB inhibitor p105, and demonstrated that p105(sr) broadly and effectively inhibits all NF-kappaB species. Overexpression of p105(sr) generates p105(sr)/p50 heterodimers and therefore, prevents formation of p50 homodimers. Formation of p105(sr)/Rel protein complexes should broadly inhibit NF-kappaB activities. Our long-term goal is to understand the role of NF-kappaB in tumorigenesis. We hypothesize that carcinogen TPA treatment of skin leads to enhanced turnover of p50 precursor p105, releasing p50 to form homodimers. The p50 homodimer, in synergy with constitutively activated Ha-ras in skin tumors, plays a role in tumorigenesis. Introduction of p105(sr) into skin tumor cells will lead to systematic dissection of NF-kappaB-regulated genes including those controlled by p50 homodimers. Such approach will also aid to facilitate apoptosis of the tumor cells mediated by TNFalpha, and chemotherapy reagents. We will study the mechanism of how p50 homodimer activity is elevated in skin tumor cells. We will also test whether introducing p105(sr) into skin tumor cells facilitates apoptosis, and whether this approach significantly affects physiologic functions of normal keratinocytes.