Risk for in vivo mutagenesis of the P53 gene by nucleoside analog antiviral drug

描述(申请人提供)：在过去的40年里，几类具有治疗价值的抗病毒药物已经开发出来，用于治疗由HIV-1、疱疹病毒和肝炎病毒引起的危及生命或虚弱的疾病，一些最有效的抗病毒药物包括核苷类似物，它们也可能损害DNA并带来长期的癌症风险。例如，包括核苷类似物在内的联合抗病毒疗法将艾滋病毒-1感染从致命疾病转变为慢性病，并极大地减少了病毒在怀孕期间的垂直传播。然而，基于核苷类似物齐多夫定(AZT)的治疗方案的巨大好处伴随着宿主细胞AZT-DNA的掺入、细胞遗传学效应以及报告基因如HIV感染母亲及其新生儿的Glyophorin A和HPRT的突变反应。这项先导性研究的主要目标是确定在子宫内使用AZT预防HIV-1是否会导致p53肿瘤抑制基因突变的增加，这些突变可能与未来暴露在风险中的儿童的癌症相关健康结果有关。我们还将评估在没有抗病毒治疗的情况下，母亲感染艾滋病毒的可能性，作为胎儿生命期间突变的潜在来源。基于聚合酶链式反应的变性梯度凝胶电泳法，使用补骨脂素夹持的引物，将用于确定宫内暴露于AZT的婴儿脐带血淋巴细胞P53外显子5-9突变的频率和性质，并与健康的未感染母亲或未接受抗病毒治疗的HIV感染母亲所生的婴儿进行比较。我们还将建立灵敏的基于PCR的等位基因特异性竞争阻滞剂分析方法，用于检测频繁发生的p53突变，通过DNA测序来检测突变，并确定标本中突变与野生型DNA的比例。人们的预期是，基于AZT的预防措施，而不是胎儿“暴露”于母体HIV-1，将导致p53基因突变。这一假设的确认将为未来的研究奠定基础，以确定癌症风险的大小，评估核苷类似物保留策略或被认为毒性较低的核苷类似物的相对安全性，并确定药物诱导的p53基因突变在HIV-1感染患者中的作用。 公共卫生相关性：需要对感染艾滋病毒的孕妇进行项目叙事治疗，以防止病毒感染婴儿；然而，目前使用齐多夫定(AZT)等核苷类似物的治疗方法可能会破坏DNA，并在以后的生命中增加患癌症的风险。这项工作的主要目标是确定怀孕期间暴露于AZT会导致P53肿瘤抑制基因突变，这可能参与癌症的进展。

DESCRIPTION (provided by applicant): The last 40 years have seen the development of several classes of antiviral drugs with therapeutic value in treating life-threatening or debilitating diseases such as those caused by HIV-1, herpesviruses, and hepatitis viruses, and some of the most effecacious antiviral agents include nucleoside analogs that also carry the potential to damage DNA and impose long-term cancer risks. For example, combination antiviral therapies including nucleoside analogs have transformed HIV-1 infection from a fatal disease to a chronic illness, and dramatically reduced vertical transmission of the virus during pregnancy. However, the great benefits of regimens based upon the nucleoside analog, zidovudine (AZT) are accompanied by host cell AZT-DNA incorporation, cytogenetic effects, and mutagenic responses in reporter genes like glyophorin A and HPRT of HIV-infected mothers and their newborns. The main goal of this pilot study is to determine if in utero HIV-1 prophylaxis using AZT causes increased occurrence of P53 tumor suppressor gene mutations that may be linked in the future to cancer-related health outcomes in exposed children. We will also assess the potential of maternal HIV-infection in the absence of antiviral treatment as a potential source of mutations during fetal life. PCR-based denaturing gradient gel electrophoresis, using psoralen-clamped primers, will be used to define the frequency and nature of mutations in p53 Exons 5-9 of cord blood lymphocytes from infants exposed in utero to AZT compared with those born to healthy uninfected mothers or HIV-infected mothers receiving no antiviral treatment. We will also develop sensitive quantitative PCR-based allele-specific competitive blocker assays for frequently occurring P53 mutations to detect the mutation with DNA sequencing and to determine the proportion of mutant to wild-type DNA in specimens. The expectation is that AZT-based prophylaxis, but not fetal "exposure" to maternal HIV-1, will induce P53 gene mutations. Affirmation of this hypothesis will lay the groundwork for future research to define the magnitude of cancer risk, to assess the relative safety of nucleoside-analog sparing strategies or nucleoside analogs thought to be less toxic, and to determine the role of drug-induced P53 gene mutations in HIV-1-infected patients. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE Treatment of HIV-infected pregnant women is needed to prevent the virus from infecting the baby; however, the current treatments that use nucleoside analogs like zidovudine (AZT) may damage DNA and impose a risk for cancer later in life. The main goal of this work is to determine exposure to AZT during pregnancy causes mutations in the P53 tumor suppressor that can be involved in the progression of cancer.