NCI CLINICAL INVESTIGATOR AWARD PROGRAM

目前的证据表明，恶性肿瘤的发病机制是 一个多阶段的现象，癌症不是由一个单一的 突变，而是一系列的突变。 体内最好的之一 研究上皮恶性肿瘤进展的模型是 小鼠两态致癌系统。 在该系统中 化学致癌物引发的TPA促进的小鼠皮肤肿瘤 可以从良性癌前乳头状瘤到 坦率的，侵袭性癌。 最近的证据表明 化学诱导的良性小鼠皮肤乳头状瘤 c-Ha-ras癌基因的突变表明， 这个基因代表了这些基因发育的第一步， 皮肤肿瘤 然而，随后的遗传事件， 这些肿瘤的发展，这可能涉及突变， 其他（癌）基因仍有待鉴定。 我们会处理这个问题 通过研究化学诱导的小鼠皮肤癌问题 携带双微小染色体（DM）的细胞系。 这些 异常结构通常与基因 扩增，我们计划利用分馏技术， 从这些细胞中分子克隆扩增编码序列 线 我们将比较这些克隆扩增的 与其他已知基因杂交， 序列分析 使用Southern、北方和狭缝印迹法 分析，我们将研究这些结构和表达 正常上皮细胞和小鼠皮肤中的序列 肿瘤恶性进展的不同阶段。 如果这样 序列似乎参与了这些皮肤的发育 肿瘤，那么我们将尝试分离同源的人类 序列，并确定这样的人类序列是否可能是 参与人类上皮恶性肿瘤的发展。

Current evidence suggests that the pathogenesis of malignancy is a multistage phenomenon, that cancer results not from a single mutation but from a series of mutations. One of the best in vivo models for studying the progression of epithelial malignancies is the mouse two-state carcinogenesis system. In this system chemical carcinogen-initiated, TPA-promoted mouse skin tumors can be serially followed from benign premalignant papillomas to frank, invasive carcinomas. Recent evidence suggests that chemically-induced benign mouse skin papillomas harbor a point mutation in the c-Ha-ras oncogene suggesting that activation of this gene represents the initial step in the development of these skin tumors. However, subsequent genetic events in the development of these tumors, which might involve mutations of other (onco)genes, remain to be identified. We will approach this question by studying chemically-induced mouse skin carcinoma cell line that harbor double minute chromosome (DMs). These aberrant structures are frequently associated with gene amplification, and we plan to utilize fractionation techniques to molecularly clone amplified coding sequences from these cell lines. We will compare the structure of these cloned amplified sequences with other known genes by hybridization and DNA sequence analysis. Using Southern, Northern and slot-blot analysis, we will study the structure and expression of these sequences in normal epithelial cells as well as in the mouse skin tumors at different stages of malignant progression. If such sequences appear to be involved in the development of these skin tumors, then we will attempt to isolate homologous human sequences and determine if such human sequences might be involved in the development of human epithelial malignancies.