Rhabdomyosarcoma fusion oncoprotein initially pioneers a neural signature in vivo.

Fusion-positive rhabdomyosarcoma is an aggressive pediatric cancer molecularly characterized by arrested myogenesis. The defining genetic driver, PAX3::FOXO1, functions as a chimeric gain-of-function transcription factor. An incomplete understanding of PAX3::FOXO1's in vivo epigenetic mechanisms has hindered therapeutic development. Here, we establish a PAX3::FOXO1 zebrafish injection model and semi-automated ChIP-seq normalization strategy to evaluate how PAX3::FOXO1 initially interfaces with chromatin in a developmental context. We investigated PAX3::FOXO1's recognition of chromatin and subsequent transcriptional consequences. We find that PAX3::FOXO1 interacts with inaccessible chromatin through partial/homeobox motif recognition consistent with pioneering activity. However, PAX3::FOXO1-genome binding through a composite paired-box/homeobox motif alters chromatin accessibility and redistributes H3K27ac to activate neural transcriptional programs. We uncover neural signatures that are highly representative of clinical rhabdomyosarcoma gene expression programs that are enriched following chemotherapy. Overall, we identify partial/homeobox motif recognition as a new mode for PAX3::FOXO1 pioneer function and identify neural signatures as a potentially critical PAX3::FOXO1 tumor initiation event.

Interprofessional Post-Graduate Training Model for Nurse Practitioners and Physician Trainees.

CONTEXT: People living with serious illness and their care partners rely on team-based specialty hospice and palliative care (HPC) in order to achieve high quality end of life outcomes. In HPC, physician and nurse practitioner (NP) scope of practice has significant overlap so training together may offer benefits to clinicians and patients. OBJECTIVES: Assessment of clinical competencies in a post-graduate training program consisting of NPs and physicians training and learning side-by-side. METHODS: A crosswalk assured NP and physician HPC clinical competencies were captured in evaluation questions used by interprofessional program faculty to observe and assess trainees. Six clinical competencies were calculated based on aggregated evaluations for each physician and NP HPC post-graduate trainee at 3, 6, 9, and 12 months annually for 3 years. For NPs and physicians, the mean slopes of the best fit lines, the final numeric score, and the mean net change between 12 and three month competencies were compared. Learner experience was captured qualitatively. RESULTS: There was no statistical difference in the change of competency scores, the final competency scores, or the trajectory of improvement in the six competencies between physician to NP trainees. Adding NP trainees was considered by post-graduate trainees as a strength of the program, and did not detract from physician competence achievement. CONCLUSION: Assessing an IPE post-graduate training program in HPC was possible using a shared clinical competency framework, and revealed similar clinical gains for NPs and physicians enrolled in the program.

A Robust Closed-Tube Method for Resolving tp53M214K Genotypes.

The tp53M214K zebrafish mutant is a versatile platform with which to model a diverse spectrum of human diseases. However, currently available genotyping methods for this mutant require lengthy hands-on processes such as restriction digests and outsourced Sanger sequencing. To address this deficiency, we leveraged high-resolution melting analysis technology in conjunction with a parallel, in-tandem wild-type spike-in approach to develop a robust genotyping protocol capable of discriminating tp53M214K zygosity. In this study, we describe our method in detail. We anticipate that our genotyping protocol will benefit researchers utilizing the tp53M214K zebrafish mutant by offering reliable results with a shorter turnaround time, lower personnel involvement, and higher throughput than traditional methods, thereby decreasing the burden of genotyping and maximizing research efficiency.

A robust closed-tube method for resolving tp53 M214K genotypes.

The tp53 M214K zebrafish mutant developed by Berghmans et al 2005 1 is a versatile platform with which to model a diverse spectrum of human diseases. However, currently available genotyping methods for this mutant require lengthy processes such as restriction digests and outsourced Sanger sequencing. To address this deficiency, we leveraged high-resolution melting analysis (HRMA) technology in conjunction with a parallel, in-tandem wildtype spike-in approach to develop a robust genotyping protocol capable of discriminating tp53 M214K zygosity. Here, we describe our method in detail. We anticipate that our genotyping protocol will benefit researchers utilizing the tp53 M214K zebrafish mutant by offering reliable results with a faster turnaround time than conventional approaches.

VGLL2-NCOA2 leverages developmental programs for pediatric sarcomagenesis.

Clinical sequencing efforts are rapidly identifying sarcoma gene fusions that lack functional validation. An example is the fusion of transcriptional coactivators, VGLL2-NCOA2, found in infantile rhabdomyosarcoma. To delineate VGLL2-NCOA2 tumorigenic mechanisms and identify therapeutic vulnerabilities, we implement a cross-species comparative oncology approach with zebrafish, mouse allograft, and patient samples. We find that VGLL2-NCOA2 is sufficient to generate mesenchymal tumors that display features of immature skeletal muscle and recapitulate the human disease. A subset of VGLL2-NCOA2 zebrafish tumors transcriptionally cluster with embryonic somitogenesis and identify VGLL2-NCOA2 developmental programs, including a RAS family GTPase, ARF6. In VGLL2-NCOA2 zebrafish, mouse, and patient tumors, ARF6 is highly expressed. ARF6 knockout suppresses VGLL2-NCOA2 oncogenic activity in cell culture, and, more broadly, ARF6 is overexpressed in adult and pediatric sarcomas. Our data indicate that VGLL2-NCOA2 is an oncogene that leverages developmental programs for tumorigenesis and that reactivation or persistence of ARF6 could represent a therapeutic opportunity.

Zebrafish her3 knockout impacts developmental and cancer-related gene signatures.

HES3 is a basic helix-loop-helix transcription factor that regulates neural stem cell renewal during development. HES3 overexpression is predictive of reduced overall survival in patients with fusion-positive rhabdomyosarcoma, a pediatric cancer that resembles immature and undifferentiated skeletal muscle. However, the mechanisms of HES3 cooperation in fusion-positive rhabdomyosarcoma are unclear and are likely related to her3/HES3's role in neurogenesis. To investigate HES3's function during development, we generated a zebrafish CRISPR/Cas9 null mutation of her3, the zebrafish ortholog of HES3. Loss of her3 is not embryonic lethal and adults exhibit expected Mendelian ratios. Embryonic her3 zebrafish mutants exhibit dysregulated neurog1 expression, a her3 target gene, and the mutant her3 fails to bind the neurog1 promoter sequence. Further, her3 mutants are significantly smaller than wildtype and a subset present with lens defects as adults. Transcriptomic analysis of her3 mutant embryos indicates that genes involved in organ development, such as pctp and grinab, are significantly downregulated. Further, differentially expressed genes in her3 null mutant embryos are enriched for Hox and Sox10 motifs. Several cancer-related gene pathways are impacted, including the inhibition of matrix metalloproteinases. Altogether, this new model is a powerful system to study her3/HES3-mediated neural development and its misappropriation in cancer contexts.