53BP1 Repair Kinetics for Prediction of In Vivo Radiation Susceptibility in 15 Mouse Strains

International audienceWe present a novel mathematical formalism to predict the kinetics of DNA damage repair after exposure to both low- and high-LET radiation (X rays; 350 MeV/n 40Ar; 600 MeV/n 56Fe). Our method is based on monitoring DNA damage repair protein 53BP1 that forms radiation-induced foci (RIF) at locations of DNA double-strand breaks (DSB) in the nucleus and comparing its expression in primary skin fibroblasts isolated from 15 mice strains. We previously reported strong evidence for clustering of nearby DSB into single repair units as opposed to the classic “contact-first” model where DSB are considered immobile. Here we apply this clustering model to evaluate the number of remaining RIF over time. We also show that the newly introduced kinetic metrics can be used as surrogate biomarkers for in vivo radiation toxicity, with potential applications in radiotherapy and human space exploration. In particular, we observed an association between the characteristic time constant of RIF repair measured in vitro and survival levels of immune cells collected from irradiated mice. Moreover, the speed of DNA damage repair correlated not only with radiation-induced cellular survival in vivo, but also with spontaneous cancer incidence data collected from the Mouse Tumor Biology database, suggesting a relationship between the efficiency of DSB repair after irradiation and cancer risk

Training promotores to lead virtual hereditary breast cancer education sessions for Spanish-speaking individuals of Latin American heritage in California.

BackgroundAwareness about hereditary breast cancer and the preventative steps to minimize disease risk is lower in Hispanic/Latina individuals than non-Hispanic White women in the United States. For this reason, we developed a promotor-based hereditary breast cancer education and risk identification program for self-identified Hispanic/Latina women, which included training promotores in basic genetics and hereditary breast cancer. This study explored promotores' experiences receiving training and participating in virtual practice sessions as well as changes in knowledge about hereditary breast cancer.MethodsA total of ten promotores underwent a two-week basic training led by the promotores organization and an eight-hour in person hereditary breast cancer training workshop. Demographic information along with pre- and post-training surveys were completed by ten promotores who participated in the training workshop. Surveys were given to determine changes in knowledge of hereditary breast cancer and genetics. Of the ten promotores, two were selected to lead community education sessions and participated in 6 semi-structured interviews. All interviews and practice sessions were conducted using a virtual platform.ResultsThe data revealed that after the 8-h workshop and practice sessions, promotores felt confident about their ability to conduct virtual education sessions with the community. Interviews identified key facilitators to success such as a supportive environment, practice presentations, and personal motivation. Learning the online platform was considered the biggest challenge by the promotores, as opposed to learning complex genetics topics.ConclusionsThese results provide further evidence supporting promotores' willingness and ability to provide health education on relatively complex topics. It also offers insight into the challenges of presenting information to vulnerable populations using an online platform and the additional support that is required to ensure a positive outcome

Community research collaboration to develop a promotores-based hereditary breast cancer education program for Spanish-speaking Latinas.

Breast cancer (BC) is the most common cancer in Latinas and the leading cause of cancer death. Latinas tend to be diagnosed at later stages, receive poorer quality care and have a higher risk of mortality than non-Latina White (NLW) women. Among women with a genetic predisposition to hereditary BC, genetic counseling can be beneficial. Latinas participate in genetic counseling at lower rates than NLW women. The goal of this study was to develop comprehensive, culturally appropriate materials for community health educators (promotores)-led hereditary BC education program for Spanish-speaking Latinas. We developed the curriculum through feedback from 7 focus groups, with a total of 68 participants (35 promotores and 33 community members). We used a mixed-methods approach that relied on quantitative analysis of survey questions and qualitative content analysis of the focus groups transcripts. Pre and post promotores' training survey responses suggested improvement in the promotores' cancer-related knowledge. Themes that emerged from the qualitative analyses were (i) barriers to health education and/or care; (ii) importance of educating the Latino community about BC and genetics and (iii) role of the promotores. Future research will further evaluate the impact of the program in promotores' knowledge and community members' screening behaviors

53BP1 Repair Kinetics for Prediction of In Vivo Radiation Susceptibility in 15 Mouse Strains.

We present a novel mathematical formalism to predict the kinetics of DNA damage repair after exposure to both low- and high-LET radiation (X rays; 350 MeV/n 40Ar; 600 MeV/n 56Fe). Our method is based on monitoring DNA damage repair protein 53BP1 that forms radiation-induced foci (RIF) at locations of DNA double-strand breaks (DSB) in the nucleus and comparing its expression in primary skin fibroblasts isolated from 15 mice strains. We previously reported strong evidence for clustering of nearby DSB into single repair units as opposed to the classic "contact-first" model where DSB are considered immobile. Here we apply this clustering model to evaluate the number of remaining RIF over time. We also show that the newly introduced kinetic metrics can be used as surrogate biomarkers for in vivo radiation toxicity, with potential applications in radiotherapy and human space exploration. In particular, we observed an association between the characteristic time constant of RIF repair measured in vitro and survival levels of immune cells collected from irradiated mice. Moreover, the speed of DNA damage repair correlated not only with radiation-induced cellular survival in vivo, but also with spontaneous cancer incidence data collected from the Mouse Tumor Biology database, suggesting a relationship between the efficiency of DSB repair after irradiation and cancer risk

Mouse genomic associations with in vitro sensitivity to simulated space radiation

Exposure to ionizing radiation is considered by NASA to be a major health hazard for deep space exploration missions. Ionizing radiation sensitivity is modulated by both genomic and environmental factors. Understanding their contributions is crucial for designing experiments in model organisms, evaluating the risk of deep space (i.e. high-linear energy transfer, or LET, particle) radiation exposure in astronauts, and also selecting therapeutic irradiation regimes for cancer patients. We identified single nucleotide polymorphisms in 15 strains of mice, including 10 collaborative cross model strains and 5 founder strains, associated with spontaneous and ionizing radiation-induced in vitro DNA damage quantified based on immunofluorescent tumor protein p53 binding protein (53BP1) positive nuclear foci. Statistical analysis suggested an association with pathways primarily related to cellular signaling, metabolism, tumorigenesis and nervous system damage. We observed different genomic associations in early (4 and 8 h) responses to different LET radiation, while later (24 hour) DNA damage responses showed a stronger overlap across all LETs. Furthermore, a subset of pathways was associated with spontaneous DNA damage, suggesting 53BP1 positive foci as a potential biomarker for DNA integrity in mouse models. Our results suggest several mouse strains as new models to further study the impact of ionizing radiation and validate the identified genetic loci. We also highlight the importance of future human in vitro studies to refine the association of genes and pathways with the DNA damage response to ionizing radiation and identify targets for space travel countermeasures.SCOPUS: ar.jinfo:eu-repo/semantics/publishe