Citations

PURPOSE External beam radiation therapy (EBRT) has gained delayed acceptance as a recommended first-line treatment modality for patients with hepatocellular carcinoma (HCC), given limited evidence that it improves overall survival (OS). We analyzed individual patient data (IPD) from an international cohort to assess OS among patients with HCC treated with EBRT. METHODS We performed a systematic review of publications that assessed EBRT, met prespecified technical standards for HCC, and reported OS (search date December 15, 2022). Corresponding authors were invited to submit IPD for the study. We performed Kaplan-Meier survival analyses to determine OS and restricted mean survival time (RMST) stratified by Barcelona Clinic Liver Cancer (BCLC) stage and treatment status (ie, treatment-naïve and experienced). We performed random effects Cox proportional hazards modeling to assess clinical characteristics associated with OS. RESULTS Data were provided on 4,913 patients treated with EBRT with a median follow-up time of 5.0 years. The median OS was 6.8 years (95% CI, 5.7 to 8.7) for BCLC-0 and 4.6 years (95% CI, 4.1 to 5.1) for BCLC-A. Among treatment-naïve patients, the median OS was not reached (95% CI, 8.6 to not reached) for BCLC-0 and was 5.4 years (95% CI, 4.5 to 6.7) for BCLC-A. In multivariable models, more advanced BCLC stage, higher tumor burden, worse performance status, and Child-Pugh class B or C were associated with a higher risk of mortality. Ablative radiation dose and more recent year of treatment were associated with a reduced risk of death. CONCLUSION To our knowledge, this study represents the largest multinational cohort of patients with HCC treated with EBRT. OS outcomes with EBRT for very early- and early-stage HCC appear to be comparable with resection, thermal ablation, and other ablative locoregional therapies. These data support the inclusion of EBRT in the BCLC HCC clinical decision-making process.

53BP1 nuclear bodies are dynamic structures with properties resembling biomolecular condensates, but the molecular determinants that govern 53BP1 higher-order assembly at DNA double-strand breaks (DSBs) remain to be established. Here, we show that 53BP1 condensation is stimulated by phosphatidylinositol 3-phosphate (PI(3)P) in vitro through a highly specific interaction with its C-terminal tandem BRCT domain (tBRCT). Consequently, mutational inactivation of the 53BP1 tBRCT domain compromised PI(3)P binding and suppressed 53BP1 optodroplet formation in vivo. We further show that rapid 53BP1 clustering following DNA damage precedes its stable assembly on DSB-flanking chromatin, requires its tBRCT, and is suppressed by sequestration of nuclear PI(3)P. Taken together, our findings identify PI(3)P binding as a mechanism that promotes the formation and maturation of 53BP1 condensate-like assemblies on damaged chromatin.

The zebrafish has emerged as an excellent model for cardiovascular research thanks to its ex-utero and rapid embryonic development, its embryonic transparent nature, and its capacity to survive in the absence of a functional cardiovascular system during the first week of development, which enables functional characterization of mutations that would otherwise induce lethality in traditional murine models. The aim of this project is to identify and characterize novel genes involved in zebrafish cardiovascular development using mutagenic gene trapping, a technique that generates random insertional mutations across the genome. We use the well-defined RP2 gene-breaking transposon system, which not only mutates, but also fluorescently tags the trapped gene product(s) (Clark, Nat Methods, 2011). RP2 also introduces loxP sites into the mutant locus, which can be used for Cre-mediated phenotype rescue by microinjection of Cre recombinase, or by crossing to tissue-specific Cre lines. From over 3000 RP2-injected embryos, 141 fish showed germline transmission. Among them, 51 expressed strong fluorescence in different tissues, including the heart, vessels, notochord, central nervous system (CNS), and eyes. Three cardiovascular lines were selected for phenotypic characterization and functional studies. RP2#C2 strain expressed fluorescence in the heart valves, CNS, eyes and pectoral fin buds. Inverse PCR in RP2#C2 demonstrated a trapped gene at meis4.1a, which encodes a homeobox transcription factor that has not been previously studied in zebrafish. RP2#121 strain expressed strong fluorescence in cardiac and skeletal muscles. RP2#91 strain showed expression in the vasculature and demonstrated a trapped gene at pdgfra. Homozygous RP2#91 mutants showed severe defects in the heart, blood flow, and other body parts including the head and musculature. We are currently creating a panel of tissue-specific Cre lines targeting tissues such as cardiomyocytes, endothelial cells and smooth muscle cells for spatiotemporal rescuing of the mutant phenotype. The generated zebrafish protein-trap lines are invaluable tools to annotate gene function, dissect the molecular mechanisms of cardiovascular development, and potentially serve as disease models.

One key bottleneck in understanding the human genome is the relative under-characterization of 90% of protein coding regions. We report a collection of 1200 transgenic zebrafish strains made with the gene-break transposon (GBT) protein trap to simultaneously report and reversibly knockdown the tagged genes. Protein trap-associated mRFP expression shows previously undocumented expression of 35% and 90% of cloned genes at 2 and 4 days post-fertilization, respectively. Further, investigated alleles regularly show 99% gene-specific mRNA knockdown. Homozygous GBT animals in ryr1b , fras1 , tnnt2a , edar and hmcn1 phenocopied established mutants. 204 cloned lines trapped diverse proteins, including 64 orthologs of human disease-associated genes with 40 as potential new disease models. Severely reduced skeletal muscle Ca 2+ transients in GBT ryr1b homozygous animals validated the ability to explore molecular mechanisms of genetic diseases. This GBT system facilitates novel functional genome annotation towards understanding cellular and molecular underpinnings of vertebrate biology and human disease.

Abstract GX15-070 is a small-molecule antagonist of the BH3-binding groove of the Bcl-2 family of proteins and can thus induce apoptosis by inhibiting the interaction between pro- and anti-apoptotic proteins. In addition, GX15-070 activates a cellular pathway, which leads to the activation of the pro-apoptotic BH3-only protein Bim, a natural cellular inhibitor of anti-apoptotic members. Together, the direct inhibition of anti-apoptotic Bcl-2 family proteins and the activation of pro-apoptotic Bim by GX15-070 can sensitize tumor cells to apoptosis. Bcl-2 family members, particularly Bcl-XL and Mcl-1 have been implicated in the survival of myeloma cells and may be responsible, in part, for drug resistance. Consequently, GX15-070 was tested against the MMRC 12 validation cell line panel, a panel of 12 standardized and annotated human myeloma cell lines (HMCLs). Western blots preformed on 8 HMCLs confirmed expression of Bcl-2, Mcl-1 and/or Bcl-XL. Basal levels of Bcl-2 and MCl-1 were relatively similar across all HMCLs studied whereas levels of Bcl-XL were variable GX15-070 inhibited the viability of all 12 myeloma cell lines as determined by MTT assay. The mean IC50 was 215 nM; range (6.4-678nM) and sensitivity did not correlate with level of Bcl-2, MCL-1 or Bcl-XL expression. On the other hand cytotoxicity to normal human blood lymphocytes, stroma and bone marrow CFUs was not observed at concentrations which were effectively cytotoxic to HMCL. Time course experiments demonstrate that apoptosis and cleavage of caspase 3 began by 12 hours and continued to increase over a 96 hour period. Co-culture with human bone marrow stroma cells (BMSCs) failed to protect HMCL from GX15-070 induced cytotoxicity. Similarly, potent MM growth factors, Interleukin 6 (IL-6) and Insulin like growth factor (IGF)-1 did not confer resistance to GX15-070. Of interest, overexpression of Bcl-2 has been shown to attenuate PS-341-induced cell death (Mitisades); however, the combination of PS-341 and GX15-070 did not reveal synergistic interaction in preliminary results. Studies looking at other drug combinations are planned. Finally, GX15-070 produced cytotoxic responses in the first primary myeloma sample tested with further testing ongoing. Mouse xenograft studies are also ongoing and will be presented. These studies indicate extensive pre-clinical activity of GX15-070 in multiple myeloma and set the stage for planned Phase II clinical trials.

Abstract HACS1 is a SH3 (Src homology 3) and SAM (sterile alpha motif) domain containing adaptor protein that is expressed in activated B and dendritic cells, is up-regulated by Interleukin 4 in the process of B cell activation and likely serves to dampen the immune response. To elucidate the function of HACS1, we generated HACS1 gene knockout mice by deletion of the SH3 and SAM domains. HACS1−/− mice were viable and fertile and had normal bone marrow B cell development and normal splenic T and B cell populations. However, adult HACS1−/− mice had increased numbers of peritoneal B1 cells (IgM+CD5+). Upon LPS plus BCR or TCR stimulations, splenic cells from HACS1−/− mice demonstrated an upregulation of activation markers with increased intensity of CD23 expression or increased population of CD69 positive cells. Purified B220+ splenic B cells from HACS1−/− mice showed increased cell proliferation upon BCR stimulation. Both T helper type 1 (Th1) and T helper type 2 (Th2) humoral responses were enhanced in HACS1−/− mice upon immunization with T cell-dependent antigen NP-KLH, which resulted in increased production of interferon-gamma (IFN-γ), anti-NP IgG2a and IL-4, as well as anti-NP IgG1 and IgE. Upon immunization with T cell-independent antigens such as TNP-LPS and TNP-Ficoll, HACS1−/− mice had increased production of anti-TNP IgM and IgG3 as compared to normal controls. The in vitro maturation of bone marrow-derived dentritic cells from HACS1−/− mice was similar to wild-type mice but HACS1−/− dentritic cells showed increased IL-12 production upon stimulation with anti-CD40 or LPS. There was no significant difference in antigen uptake by cultured dentritic cells from non-immunized wild-type or knockout mice. However, in immunized mice, an increase in antigen uptake in HACS1−/− dentritic cells was observed. We further demonstrate that the HACS1−/− B cells had increased tyrosine phosphorylation in the resting state. As deletion of the SH3 & SAM domains of HACS1 appears to generate a hypersensitive immune response, our results collectively support that HACS1 negatively regulates adaptive immunity.

Cardiac development in vertebrates is a finely tuned process regulated by a set of conserved signaling pathways. Perturbations of these processes are often associated with congenital cardiac malformations. Platelet-derived growth factor receptor α (PDGFRα) is a highly conserved tyrosine kinase receptor, which is essential for development and organogenesis. Disruption of Pdgfrα function in murine models are embryonic lethal due to severe cardiovascular defects, suggesting a role in cardiac development, thus necessitating the use of alternative models to explore its precise function. In this study, we generated a zebrafish pdgfra mutant line by gene trapping, in which the Pdgfra protein is truncated and fused with mRFP (Pdgfra-mRFP). Our results demonstrate that pdgfra mutants have defects in cardiac morphology as a result of abnormal fusion of myocardial precursors. Expression analysis of the developing heart at later stages suggested that Pdgfra-mRFP is expressed in the endocardium. Further examination of the endocardium in pdgfra mutants revealed defective endocardial migration to the midline, where cardiac fusion eventually occurs. Together, our data suggests that pdgfra is required for proper medial migration of both endocardial and myocardial precursors, an essential step required for cardiac assembly and development.

Abstract Human chromosome 13q14 is one of the hotspots of chromosomal deletion in prostate cancer, multiple myeloma, and chronic lymphocytic leukemia. Chromosome Condensation 1-like (CHC1L) is an uncharacterized gene in this region. CHC1L is found within the smallest common region of loss of heterozygosity in prostate cancer, and its decreased expression is linked to pathogenesis and progression of both prostate cancer and multiple myeloma. In the present study, we describe the generation and characterization of Chc1L gene knockout mice. Knockout mice develop normally and display an exaggerated proliferative response to LPS stimulation of cultured bone marrow and spleen cells at ten weeks of age. At approximately two years of age, both homozygous and heterozygous mice have markedly increased incidence of tumorigenesis, 80% and 56% respectively, compared to wild-type mice, 26%. The tumors are distributed most commonly to the spleen, mesenteric lymph nodes, liver and small intestine. The morphologic and immunophenotypic features of the tumor cells are consistent with those of tissue histiocytes, and most Chc1L knockout and heterozygote mice succumb to either Histiocytic Sarcoma or Histiocyte-Associated Lymphoma. These data provide the first direct evidence that Chc1L is a tumor suppressor gene involved in suppression of histiocyte-rich neoplasms. Citation Format: David Spillane, Ding Yan Wang, Changxin Shi, Youdong Wang, Anthony Gramolini, Keith Stewart, Susan Newbigging, Mingyao Liu, Xiao-Yan Wen. Chc1L is a tumor suppressor involved in development of histiocyte-rich neoplasms. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr C41.