MEMBRANE SIGNAL TRANSDUCTION IN TUMOR PROMOTION

这项研究的总体目标是鉴定和表征基因 在肿瘤过程中推动限速步骤的调节事件 促进和肿瘤进展。AP-L转录因子是一种 Jun和Fos家族蛋白的异源二聚体与特定的 某些基因和驱动的转录启动子的序列 他们的抄本。我们1989年的观察(伯恩斯坦和科尔本， 科学，1989)对促销敏感(P+)，但不促销 耐药(P-)小鼠JB6细胞对肿瘤促进剂的反应 激活AP-L依赖的转录，提示AP-1激活 可能是从癌前病变进展到肿瘤所必需的 (肿瘤)表型。对这一假说的初步检验表明， 药物抑制剂、糖皮质激素和维甲酸及其“基因” 治疗“抑制剂显性阴性Jun(TAM67)阻断AP-1 激活和转化反应。这一点已经扩展到显示 转录因子特异性维甲酸转录抑制AP-L 不反式激活维甲酸反应元件的活性(罕见) 依赖基因转录，也能防止肿瘤转化 (Li等人，癌症资源，1996)。显性负Jun突变体(TAM67) 由角蛋白14(KL4)启动子驱动的转基因在 小鼠角质形成细胞系308对AP-L和NFkappaB的抑制作用 转录因子活性以及诱导侵袭 Matrigel(董等人，Molec.癌症，在印刷中)暗示 第二转录因子NFkappaB在两者中的可能重要性 进展的原因和预防。AP-1和NFkappaB 人类的活动和DNA结合呈进行性升高 角质形成细胞进展模型。当转基因KL4-TAM67 在进展较快的人类细胞系中表达 肿瘤形成或锚定无关，肿瘤细胞表型为 被压制(Li等人，正在准备中)。在体内的扩展是 正在进行中。TAM67在小鼠JB6P+细胞中的表达 当细胞在移植物床上生长时，细胞回复到P表型 (Strickland等人，正在准备中)。表达K-蛋白的转基因小鼠 已产生14-TAM67转基因。两位创始人的后代将 以可能的保护作用为特征，防止皮肤促进 致癌，即预防癌前乳头状瘤的形成。 因此，靶向转录因子AP-1和NFkappaB出现了 有望预防和治疗癌症。

The overall aim of this research is to identify and characterize gene regulation events that propel rate limiting steps during tumor promotion and tumor progression. The AP-l transcription factor is a heterodimer of Jun and Fos family proteins that binds to a specific sequence on the transcriptional promoter of certain genes and drives their transcription. Our 1989 observation (Bernstein and Colburn, Science, 1989) that promotion sensitive (P+) but not promotion resistant (P-) mouse JB6 cells responded to tumor promoters by activating AP-l dependent transcription, suggested that AP-1 activation might be required for progression from preneoplastic to neoplastic (tumor) phenotype. Initial testing of this hypothesis revealed that the pharmacologic inhibitors, glucocorticoids and retinoids and the "gene therapy" inhibitor dominant negative jun (TAM67) blocked both AP-1 activation and transformation response. This has been extended to show that transcription factor specific retinoids that transrepress AP-l activity without transactivating retinoic acid response element (RARE) dependent gene transcription, also prevent neoplastic transformation (Li et al., Cancer Res, 1996). The dominant negative jun mutant (TAM67) transgene driven by a keratin 14 (Kl4) promoter, when expressed in a mouse keratinocyte line 308 suppressed both AP-l and NFkappaB transcription factor activities as well as induced invasion into matrigel (Dong et al., Molec. Carcinog., in press) suggesting the possible importance of a second transcription factor NFkappaB in both the cause and prevention of progression. Both AP-1 and NFkappaB activities and DNA binding show progressive elevation in a human keratinocyte progression model. When the transgene Kl4-TAM67 is expressed in the more progressed-stage human cell lines that are tumorigenic or anchorage independent, tumor cell phenotype is suppressed (Li et al., in preparation). In vivo extensions are underway. Expression of TAM67 in mouse JB6 P+ cells produced phenotypic reversion to P- phenotype when cells were grown on a graft bed (Strickland et al., in preparation). Transgenic mice expressing the K- 14-TAM67 transgene have been generated. Progeny of two founders will be characterized for possible protection against promotion of skin carcinogenesis, i.e., prevention of premalignant papilloma formation. Thus, targeting transcription factors AP-1 and NFkappaB appears promising for prevention and treatment of cancer.