The DNA damage response (DDR) induces the expression of type I interferons (IFNs), but the underlying mechanisms are poorly understood. Here, we show the presence of cytosolic DNA in different mouse and human tumor cells. Treatment of cells with genotoxic agents increased the levels of cytosolic DNA in a DDR-dependent manner. Cloning of cytosolic DNA molecules from mouse lymphoma cells suggests that cytosolic DNA is derived from unique genomic loci and has the potential to form non-B DNA structures, including R-loops. Overexpression of Rnaseh1, which resolves R-loops, reduced the levels of cytosolic DNA, type I Ifn transcripts, and type I IFN-dependent rejection of lymphoma cells. Live-cell imaging showed a dynamic contact of cytosolic DNA with mitochondria, an important organelle for innate immune recognition of cytosolic nucleotides. In summary, we found that cytosolic DNA is present in many tumor cells and contributes to the immunogenicity of tumor cells.

Lumacaftor, a drug already in clinical use, can rescue the pathological phenotype of LQT2 iPSC-CMs, particularly those derived from Class 2 mutated patients. Our results suggest that the use of LUM in LQT2 patients not protected by β-blockers is feasible and may represent a novel therapeutic option.

Mechanisms determining intrinsic differentiation bias inherent to human pluripotent stem cells (hPSCs) toward cardiogenic fate remain elusive. We evaluated the interplay between ErbB4 and Epidemal growth factor receptor (EGFR or ErbB1) in determining cardiac differentiation in vitro as these receptor tyrosine kinases are key to heart and brain development in vivo. Our results demonstrate that during cardiac differentiation, cell fate biases exist in hPSCs due to cardiac/ neuroectoderm divergence post cardiac mesoderm stage. Stage-specific up-regulation of EGFR in concert with persistent Wnt3a signaling post cardiac mesoderm favors commitment toward neural progenitor cells (NPCs). Inhibition of EGFR abrogates these effects with enhanced (>twofold) cardiac differentiation efficiencies by increasing proliferation of Nkx2-5 expressing cardiac progenitors while reducing proliferation of Sox2 expressing NPCs. SIGNIFICANCE STATEMENTThe mechanism determining intrinsic cardiac differentiation bias in human pluripotent stem cells (hPSCs) remains elusive. In this study, by evaluating the interplay between ErbB receptor tyrosine kinases (RTKs) an antagonistic role between EGFR and ErbB4 was established which linked to canonical and noncanonical Wnt signaling. This convergence between ErbB and Wnt signaling determined cardiac or neuroectoderm specification in hPSCs. This study extends our understanding on signaling pathway convergence and dissects a molecular mechanism which could alter fate of differentiating hPSCs. These findings not only broaden our understanding of hPSC differentiation, but also advance our knowledge on the signaling cross-talk which tightly regulates cardiac fate determination.

Activation of signal transducer and activator of transcription 3 (STAT3) is imperative for mammalian development, specifically cardiogenesis. STAT3 phosphorylation and acetylation are key post-translational modifications that regulate its transcriptional activity. Significance of such modifications during human cardiogenesis remains elusive. Using human pluripotent stem cells to recapitulate cardiogenesis, two independently modified STAT3α (92 kDa) isoforms (phosphorylated and acetylated), which perform divergent functions were identified during cardiomyocyte (CM) formation. Phosphorylated STAT3α functioned as the canonical transcriptional activator, while acetylated STAT3α underwent caspase-3-mediated cleavage to generate a novel STAT3ζ fragment (∼45 kDa), which acted as a molecular adaptor integral to the ErbB4-p38γ signaling cascade in driving CM formation. While STAT3α knockdown perturbed cardiogenesis by eliminating both post-translationally modified STAT3α isoforms, caspase-3 knockdown specifically abrogates the function of acetylated STAT3α, resulting in limited STAT3ζ formation thereby preventing nuclear translocation of key cardiac transcription factor Nkx2-5 that disrupted CM formation. Our findings show the coexistence of two post-translationally modified STAT3α isoforms with distinct functions and define a new role for STAT3 as a molecular adaptor that functions independently of its canonical transcriptional activity during human cardiogenesis. Stem Cells 2017;35:2129-2137.

Background: To enable genomic care for all City of Hope (COH) patients, we implemented an enterprise-wide Precision Medicine program including 7 of our clinical network sites. Consented patients with and without cancer are eligible to opt into germline testing (155 gene cancer predisposition panel and ACMG 59 Actionable Disorders panel) and paired tumor-normal whole exome/RNA transcriptome sequencing. All assays are CAP-CLIA approved. Results are added to the electronic medical record (EMR). We describe the process of implementation through return of results (RoR). Methods: Potentially eligible patients are identified by their provider or through the EMR. Clinical Research Assistants (n=8, main campus) and Advance Practice Providers (APPs) (n=14 Genetic Counselors or n=1 Genetics Nurse Practitioner) and Licensed Vocational Nurses (n=5, clinical network) consent patients in-person and remotely. Clinical Research Nurses (n=5) or APPs order testing through the EMR, with treating providers copied on somatic results and GCs copied on germline results. All results are systematically reviewed by GCs and/or the weekly COH Precision Oncology Tumor Board (POTB). Results: From July 9, 2020 through August 26, 2022 12,105 patients have been offered participation, with 10,376 (85.7%) enrolling (7,892 original consents/ 2,484 reconsents), 735 (6.1%) declining, 984 (8.1%) deferring, and 10 (.1% ) with other consent statuses. 98.9% (10,259/10,376) opted for cancer predisposition germline testing and 98.5% (10,225/10,376) opted for ACMG Actionable Disorders testing 91.5% (9,497/10,376) patients agreed to future contact about additional research studies. 6,512 somatic tests have been reviewed (representing 6,295 patients) and presented through POTB. Somatic genomic results are uploaded to the EMR via PDF and returned by the treating physician. Germline results are returned through the EPIC genomics module. To scale RoR, patients with negative results, variants of unknown significance, and carriers for recessive conditions are sent letters. Patients with a cancer predisposition P/LP variant are disclosed via phone by a GC and referred to COH Cancer Genomics for counseling whereas patients with P/LP non-cancer ACMG variants are referred for outside genetic counseling through the testing laboratory. To improve efficiency, we do not notify patients of non-actionable variant reclassifications. Conclusion: We outline a new care model for the delivery of germline and somatic genetic testing at scale. High consent and opt-in rates for germline testing demonstrate patient interest and feasibility. Future work is planned to assess the impact of testing on clinical care and outcomes. Citation Format: Ilana Solomon, Heather Hampel, Kevin McDonnell, Kathleen Blazer, Alex Capasso, Anuja Chitre, Sandra Dreike, Hunaydah Elfarawi, Lauren Gima, Christine Hong, Gregory Idos, Elisabeth King, Rachelle Manookian, Bita Nehoray, Wai Park, Michael Restrepo, Susan Shehayeb, Elise Sobotka, Duveen Sturgeon, Elyssa Zukin, Stacy W. Gray, Stephen B. Gruber. The INSPIRE Study (Implementing Next-generation Sequencing for Precision Intervention and Risk Evaluation): scaling return of genomic results. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P051.