Using Synthetic Lethality to Select Cancer Drug Targets

描述(申请人提供)：功能丧失肿瘤抑制基因(TSG)突变在癌症中很常见。如果两个基因中的任何一个单独失活与生存能力相容，那么这两个基因就是“合成致命的”，但两个基因的失活都会导致死亡。从理论上讲，对突变的TSG具有合成致命性的基因的产物将成为一个有吸引力的药物靶点，因为它的抑制作用应该会杀死TSG(-/-)癌细胞，但不会杀死正常的[TSG(+/+)]细胞。我们选择了VHL肿瘤抑制基因，它在大多数透明细胞肾癌中发生突变，以进一步探索这一范式。重要的是，VHL基因产物pVHL的失活并不会严重影响细胞在体外的生长，否则可能会扰乱我们的研究。此外，我们有多个匹配的(等基因)肾癌细胞(RCC)株，它们含有或不含有野生型pVHL以及VHL(+/+)和VHL(-/-)线虫。缺乏pVHL的细胞过度产生一种称为HIF(缺氧诱导因子)的转录因子。因此，VHL(-/-)RCC的转录类似于低氧细胞，低氧细胞在实体瘤中很常见，已知具有相对的化疗耐药性。在具体目标1中，我们将使用化学生物学方法寻找选择性杀死VHL(-/-)RCC的化合物。然后，这些化合物可能会被用作探针，以确定它们的蛋白质靶标。在具体目标2中，我们将使用全基因组RNAi方法来识别选择性杀死VHL(-/-)线虫的基因。这些基因随后将在人类RCC中被重复。二级筛查将解决HIF调节失调是否导致VHL(-/-)和VHL(+/+)细胞对特定目标1和2的不同敏感性。这些实验可能识别肾癌的新药物靶点，特别是一般的乏氧肿瘤细胞。此外，他们可能建立一种基于TSG失活突变的抗癌药物靶点选择的新范式。

DESCRIPTION (provided by applicant): Loss of function tumor suppressor gene (TSG) mutations are common in cancer. Two genes are 'synthetically lethal' if inactivation of either gene alone is compatible with viability but inactivation of both genes leads to death. In theory, the product of a gene that was synthetically lethal to a mutated TSG would be an attractive drug target because its inhibition should kill TSG(-/-) cancer cells but not normal [TSG( +/+)] cells. We have chosen the VHL tumor suppressor gene, which is mutated in the majority of clear cell renal carcinomas, to explore this paradigm further. Importantly, inactivation of the VHL gene product, pVHL, does not grossly affect cell growth in vitro, which might otherwise confound our studies. Moreover, we have multiple matched (isogenic) renal carcinoma cell (RCC) lines that do or do not contain wild-type pVHL as well as VHL(+/+) and VHL (-/-) C. elegans. Cells lacking pVHL overproduce a transcription factor called HIF (hypoxia-inducible factor). Consequently, the transcriptomes of VHL (-/-) RCCs resemble that of hypoxic cells, which are common in solid tumors and known to be relatively chemoresistant. In specific aim 1 we will use chemical biological approaches to look for compounds that selectively kill VHL(-/-) RCCs. Such compounds might then be used as probes to identify their protein targets. In specific aim 2, we will use a genome-wide RNAi approach to identify genes that selectively kill VHL (-/-) C. elegans. These genes would then be interogated in human RCCs Secondary screens will address whether dysregulation of HIF is responsible for differential sensitivity of VHL (-/-) and VHL (+/+) cells in specific aims 1 and 2. These experiments may identify new drug targets for renal carcinoma, in particular, and hypoxia tumor cells, in general. Moreover, they may establish a new paradigm for the selection of anticancer drug targets based on inactivating mutations of TSG.