Study of the Effect of SNPs in p53 and p53 Response Elements on the Inflammatory Response to DNA Damage

Cancer Clinical Trial

Official title: Effect of SNPs in p53 and p53 Response Elements on the Inflammatory Response to DNA Damage

Status Completed

Clinical Trial Summary

Background:

• Research has shown that certain proteins in cells may be linked to higher risks of developing inflammations, tumors, and other medical problems. By examining how the blood cells of healthy volunteers respond to environmental exposures, researchers hope to better understand the relationship of genes, environmental factors, and human diseases.

Objectives:

• To examine how specific genes and proteins in blood cells respond to environmental exposures.

Eligibility:

• Healthy volunteers between 18 and 45 years of age.

Design:

• The study will involve one visit of 45 to 60 minutes.

• Participants will be screened with a brief physical examination and finger stick to determine if they are eligible to donate blood for the study, and will complete a questionnaire about any medications or other drugs (e.g., cigarettes) they may be taking.

• Participants will provide a blood sample for research purposes.

Clinical Trial Description

This research study will investigate the role of SNPs in p53 and p53 response elements on the inflammatory response to DNA damage. A total of 200 participants aged 18 years and older carrying one of the five SNPs of interest and wild-type controls will be identified and recruited from the Environmental Polymorphism Registry (EPR). In addition, participants will be recruited based on their health outcomes and SNP associations from the EPR registry to study genotype-phenotype effects on lymphocytes. The EPR is a long-term project to collect and store up to 15,000 DNA samples for use in research studies from individuals in the greater North Carolina Triangle Region.

This observational gene association study will recruit participants on the basis of genotype or phenotype and then observe the lymphocyte response to chemotherapeutic agents and relevant environmental pathogens. The SNPs of interest are p53, as well as four of its downstream target genes including FLT1, MDM2, TLR8 and RRM1. A maximum of 320 mLs of blood will be obtained from each participant during one visit lasting approximately one hour. Cells from the donated blood samples will be examined for their response to exposed environmental stress ex vivo.

The primary objective is to determine the association between five SNPs and p53 target gene expression after exposure to Nutlin or doxorubicin (chemotherapeutic agents) with outcome measured by RT-PCR. The five SNPs are p53 rs1042522, MDM2 rs2279744, FLT1 C-677T, TLR8 rs3761624 and RMM1 rs1465952. The secondary objectives are to: (1) to determine the p53 promoter occupancy measured by ChIP analysis for the following SNPs: FLT1 C-677T, TLR8 rs3761624 and RMM1 rs1465952; (2) to measure apoptosis by Annexin V-PI assay for p53 rs1042522 SNPs; (3) to examine the cell cycle profile analysis (FACS) by cytofluorometry for p53 rs1042522SNPs; and (4) to determine DNA repair using Pulse Field Electrophoresis Gel (TAFE gels) for the following p53 rs1042522SNPs. Furthermore, the association between the SNPs of interest and phenotypic characteristics will be explored using the EPR health and exposure survey to identify significant genotype-phenotype associations in the EPR population. The effect of the associations will be tested on lymphocyte function after exposure to Nutlin or doxorubicin.

We have established that p53 can greatly alter expression of many immune genes including most of the toll-like receptor (TLR) innate immunity genes which are considered important components of antiviral immunity against HIV infection. Given the unique roles of TLR signaling during acute HIV-1 infection and their potential role in chronic inflammation, it is important to elucidate whether TLR polymorphisms contribute to HIV-1 pathogenesis and variability in disease progression.

Recently, we confirmed that p53 can target the TLR8 ssRNA responsive receptor in a single nucleotide polymorphism (SNP)-dependent manner (rs3761624). We have shown in a human study that a SNP within a p53 response element of the TLR8 promoter can strongly influence respiratory syncytial virus (RSV)-associated disease in infants. In addition, there are SNPs in the coding region of p53 that alter the amplitude of signaling attributed to this protein. Projecting these findings to HIV and AIDS, we hypothesize that p53 is a downstream effector that initiates anti-proliferative innate immune responses to viruses and other pathogens, establishing a new role for p53. These novel investigations will provide critical understanding of the role of innate restriction factors in resistance to HIV-1 and disease progression.

Overall, we hope the results of this study lead to discovery of important information regarding the role of SNPs located in p53 and p53 response elements in human disease, potentially identifying new targets for future studies. ;

Related Conditions & MeSH terms

• Cancer
• Cardiomyopathies
• Cardiomyopathy
• HIV-1 Seropositive
• Inflammation

• NCT number: NCT01143519
• Study type: Observational
• Source: National Institutes of Health Clinical Center (CC)
• Status: Completed
• Start date: May 21, 2012