P53 GENE AND CHEMOSENSITIVITY

我们提出了五个具体的目标，将阐明遗传的作用， 儿童横纹肌肉瘤影响敏感性的变化 抗癌剂，以及如何诱导细胞毒性的阈值， 可以调制响应。 我们的长期目标是建立新的 这些肿瘤的治疗方法。 该提案将侧重于 p53肿瘤抑制基因在一系列独特的儿科疾病中的作用 腺泡型横纹肌肉瘤和胚胎型横纹肌肉瘤 在SJCRH建立的未处理和 既往接受过治疗的患者， 破坏DNA。 我们的假设是药物敏感性将取决于 p53的功能状态，一种功能性凋亡途径， Bcl-2家族的p53可调节的存活因子， 特异性癌基因表达。 首先，利用具有诱导型wtp 53的ARMS模型系统， 表达，我们将阐明光谱致敏六 不同类型的DNA损伤剂，因为我们已经表明， p53依赖性细胞毒性，例如放线菌素-D和阿霉素， 拓扑异构酶I和拓扑异构酶II抑制剂的p53独立性 拓扑替康和VP-16。 其次，我们将确定 类似的增强作用扩展到其它ARMS和ERMS细胞系 在用WTP 53腺病毒转导的细胞进行药物处理后。 我们的假设是药物致敏的范围和程度 在c-Myc、N-Myc或致癌K-Ras的存在下， 在MDM 2扩增的存在下过表达或减少。 这 将在稳定转染的同基因组中进行第三次特异性靶向检测 ARMS和ERMS的细胞系，具有癌基因的特异性改变。 在存在wtp 53的情况下，N-Myc的药物致敏性将分配给一个 以前未鉴定的N-Myce凋亡作用。 第四，我们将 确定体外衍生的原则是否可以应用于 细胞系作为体内异种移植物。 最后， p53功能状态与横纹肌肉瘤化疗疗效的关系 将被确定。 最终，我们有可能选择 根据肿瘤的遗传特征进行适当的治疗。

We propose five specific aims that will elucidate the role of genetic alterations in pediatric rhabdomyosarcomas in influencing sensitivity to anticancer agents, and how the threshold for inducing a cytotoxic response may be modulated. Our long range goal is to establish new approaches to therapy of these tumors. The proposal will focus on the role of the p53 tumor suppressor gene in a unique series of pediatric alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS) cell lines and xenografts established at SJCRH from both untreated and previously treated patients in determining sensitivity to agents that damage DNA. Our hypothesis is that drug sensitivity iwll depend upon the functional status pf p53, a functional apoptotic pathway determined by p53-regulatable survival factors of the Bcl-2 family, and the specific oncogene expressed. Firstly, utilizing an ARMS model system with inducible wtp53 expression, we will elucidate the spectrum of sensitization to six different classes of DNA damaging agents, since we have shown p53-dependent cytotoxicity for e.g. actinomycin-D and doxorubicin and p53-independence for the topoisomerase I and topisomerse II inhibitors topotecan and VP-16, respectively. Secondly, we will determine whether similar potentiation is extended to other ARMS and ERMS cell lines following drug treatment of cells transduced with wtp53 adenovirus. Our hypothesis is that the spectrum and degree of drug sensitization will be enhanced in the present of c-Myc, N-Myc or oncogenic K-Ras overexpression or reduced in the presence of MDM2 amplification. This will be tested in the third Specific Aim in stably transfected isogenic cell lines of ARMS and ERMS with specific alterations in the oncogene. Drug sensitization for N-Myc in the presence of wtp53 would assign a previously unidentified apoptotic role to N-Myce. Fourthly, we will determine whether principles derived in vitro can be applied to the cell lines as xenografts in vivo. Finally, the relationship between p53 functional status and the clinical response of RMS to chemotherapy will be determined. Ultimately it may be possible to select appropriate therapy based upon the genetic profile of the tumor.