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

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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.