Acetyl transferase EP300 deficiency leads to chronic replication stress mediated by defective fork protection at stalled replication forks.

Mutations in the epigenetic regulator and global transcriptional activator, E1A binding protein (EP300), is being increasingly reported in aggressive hematological malignancies including adult T-cell leukemia/lymphoma (ATLL). However, the mechanistic contribution of EP300 dysregulation to cancer initiation and progression are currently unknown. Independent inhibition of EP300 in human cells results in the differential expression of genes involved in regulating the cell cycle, DNA replication and DNA damage response. Nevertheless, specific function played by EP300 in DNA replication initiation, progression and replication fork integrity has not been studied. Here, using ATLL cells as a model to study EP300 deficiency and an p300-selective PROTAC degrader, degrader as a pharmacologic tool, we reveal that EP300-mutated cells display prolonged cell cycle kinetics, due to pronounced dysregulations in DNA replication dynamics leading to persistent genomic instability. Aberrant DNA replication in EP300-mutated cells is characterized by elevated replication origin firing due to increased replisome pausing genome-wide. We demonstrate that EP300 deficiency results in nucleolytic degradation of nascently synthesized DNA at stalled forks due to a prominent defect in fork stabilization and protection. This in turn results in the accumulation of single stranded DNA gaps at collapsed replication forks, in EP300-deficient cells. Inhibition of Mre11 nuclease rescues the ssDNA accumulation indicating a dysregulation in downstream mechanisms that restrain nuclease activity at stalled forks. Importantly, we find that the absence of EP300 results in decreased expression of BRCA2 protein expression and a dependency on POLD3-mediated error-prone replication restart mechanisms. The overall S-phase abnormalities observed lead to under-replicated DNA in G2/M that instigates mitotic DNA synthesis. This in turn is associated with mitotic segregation defects characterized by elevated micronuclei formation, accumulation of cytosolic DNA and transmission of unrepaired inherited DNA lesions in the subsequent G1-phase in EP300-deficient cells. We demonstrate that the DNA replication dynamics of EP300-mutated cells ATLL cells recapitulate features of BRCA-deficient cancers. Altogether these results suggest that mutations in EP300 cause chronic DNA replication stress and defective replication fork restart results in persistent genomic instability that underlie aggressive chemo-resistant tumorigenesis in humans.

"No one size fits all" A Multi-Method Survey of Oncology Allied Health Professionals Experiences with Lesbian, Gay, Bisexual, Transgender/Queer Questioning Adolescent, and Young Adult Patients with Cancer and Reproductive and Sexual Health".

Objectives: To assess training needs for providers who care for adolescent and young adult (AYA) lesbian, gay, bisexual, transgender/queer questioning (LGBTQ) cancer patients, we conducted a mixed-method survey. During their cancer care experience, AYA cancer patients experience physical, psychosocial, and reproductive health challenges. In addition to these challenges, AYA LGBTQ individuals are a diverse and medically underserved population who experience unique challenges and disparities in medical care. Methods: Health care providers (n = 351) who participated in our reproductive health in cancer training program completed a survey with 28 quantitative items and 4 open-ended items assessing knowledge, confidence discussing reproductive health, and confidence in knowledge specific to reproductive needs and general health needs among AYA LGBTQ patients. Results: Confidence discussing and confidence in knowledge of reproductive and general health needs are lower regarding transgender and nonbinary patients. Nearly half of providers (45%) demonstrated low knowledge, while 38% and 17% demonstrated moderate and high knowledge, respectively. Open comments indicated providers desired more training around the needs of Trans and nonbinary patients, and creating welcoming environments. Conclusions: The majority of our participants demonstrate low or moderate knowledge regarding factors that can influence AYA LGBTQ patient care, suggesting that this is a key area for improvement. Furthermore, improving provider knowledge may subsequently improve confidence in general and reproductive needs of LGBTQ patients, resulting in improved patient-centered care. Improving provider knowledge and confidence may then ultimately help reduce disparities in cancer care among this patient population.

The LOvE ECHO Training: Developing a Web-Based LGBTQ Cultural Competency Training Module for Oncology Allied Health Professionals.

Purpose: This article describes the development of the LGBTQ Oncofertility Education (LOvE-ECHO). The Enriching Communication skills for Health professionals in Oncofertility (ECHO) team created this new education module in response to the needs of oncology allied health professionals to provide inclusive and affirming care to lesbian, gay, bisexual, transgender, and queer (LGBTQ) AYA patients with cancer. The new module is part of the ECHO, a web-based educational training program for oncology allied health professionals to improve communication with AYA about reproductive health. Methods: The development of LOvE-ECHO includes five phases-learner needs assessment, content development and revision, piloting, and finalizing. Results from a survey of past ECHO learners and a comprehensive literature review provided the basis of need for this module and identified the most prominent gaps in knowledge and training. Content development and revision were iterative, including input, feedback, and voices from LQBTA youth and survivors, researchers, reproductive health experts, oncology clinicians, and web developer. Results: The complete LOvE-ECHO module consists of both didactic and interactive lessons. A glossary of terms and narrated PowerPoint establishes a knowledge base and shared vocabulary. Three interactive cases and a plan for action provide learners opportunities to test their new knowledge and transfer it to their practice. Conclusion: The module has received positive feedback to date. It is currently being piloted with new learners who complete a pre-test and post-test, as well as a feedback survey. Analysis of these results will inform revisions to the module.