P53 GENE AND CHEMOSENSITIVITY

我们提出了五个具体的目标，将阐明基因的作用 影响儿童横纹肌肉瘤敏感性的改变 对于抗癌药，以及如何诱导细胞毒的阈值 可以对响应进行调制。我们的长期目标是建立新的 这些肿瘤的治疗方法。该提案将重点放在 P53抑癌基因在一系列独特的儿科肿瘤中的作用 泡状横纹肌肉瘤(ARM)和胚胎型横纹肌肉瘤(ERMS) 在SJCRH建立的细胞系和异种移植 以前治疗过的患者在确定对以下药物的敏感性方面 破坏DNA。我们的假设是药物敏感性将取决于 功能性细胞凋亡途径P53的功能状态确定 通过P53调控的Bcl2家族生存因子，以及 表达了特异的癌基因。 首先，利用带有可诱导的wtp53的武器模型系统 表达，我们将阐明致敏光谱的六个方面 不同类别的DNA损伤剂，因为我们已经展示了 P53依赖的细胞毒性，例如放线菌素-D和阿霉素和 拓扑异构酶I和拓扑异构酶II抑制剂的P53非依赖性 拓扑替康和VP-16。其次，我们将确定是否 类似的增强作用也扩展到其他ARM和ERMS细胞系 对转导wtp53腺病毒的细胞进行药物治疗。 我们的假设是药物致敏的光谱和程度 将在c-Myc、N-Myc或致癌K-RAS的存在中增强 在MDM2扩增存在的情况下，过表达或下调。这 将在第三个特定目标中进行测试，稳定地转导等基因 致癌基因发生特殊改变的上臂和ERM细胞系。 在wtP53存在的情况下对N-Myc的药物增敏将分配一个 之前未知的N-Myce对细胞凋亡的作用。第四，我们将 确定体外衍生的原理是否可以应用于 体内异种移植的细胞系。最后，两者之间的关系 P53功能状态与RMS对化疗的临床反应 将会被确定。最终，可能会选择 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.