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

描述（由申请人提供）：在过去的40年中，已经开发了几类在治疗危及生命或使人衰弱的疾病（例如由HIV-1、疱疹病毒和肝炎病毒引起的疾病）中具有治疗价值的抗病毒药物，并且一些最有效的抗病毒药物包括核苷类似物，其也具有损伤DNA和施加长期癌症风险的潜力。例如，包括核苷类似物在内的联合抗病毒疗法已将HIV-1感染从致命疾病转变为慢性疾病，并大大减少了妊娠期间病毒的垂直传播。然而，基于核苷类似物齐多夫定（AZT）的方案的巨大益处伴随着宿主细胞AZT-DNA掺入、细胞遗传学效应和报告基因（如HIV感染母亲及其新生儿的Glyophorin A和HPRT）的诱变反应。这项初步研究的主要目的是确定使用AZT进行子宫内HIV-1预防是否会导致P53肿瘤抑制基因突变的发生率增加，这些突变可能在未来与暴露儿童的癌症相关健康结局有关。我们还将评估在没有抗病毒治疗的情况下，母体HIV感染作为胎儿生命期间突变的潜在来源的可能性。将使用PCR变性梯度凝胶电泳（使用PCR夹持引物）确定子宫内暴露于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，并与健康未感染母亲或未接受抗病毒治疗的HIV感染母亲所生婴儿进行比较。我们还将开发灵敏的基于定量PCR的等位基因特异性竞争性阻断剂检测方法，用于检测频繁发生的P53突变，通过DNA测序检测突变，并确定标本中突变型与野生型DNA的比例。预期AZT为基础的预防，而不是胎儿“暴露”于母体HIV-1，将诱导P53基因突变。这一假设的肯定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核苷类似物的相对安全性被认为是毒性较小，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：艾滋病毒感染的孕妇需要治疗，以防止病毒感染婴儿;然而，目前使用核苷类似物如齐多夫定（AZT）的治疗可能会损害DNA，并在以后的生活中增加患癌症的风险。这项工作的主要目标是确定在怀孕期间暴露于AZT导致P53肿瘤抑制基因突变，这可能与癌症的进展有关。

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.