Image-Guided Deployment and Monitoring of a Novel Tungsten Nanoparticle-Infused Radiopaque Absorbable Inferior Vena Cava Filter in a Swine Model

PURPOSE

To improve radiopacity of radiolucent absorbable poly-p-dioxanone (PPDO) inferior vena cava filters (IVCFs) and demostrate their effectiveness in clot-trapping ability.

MATERIALS AND METHODS

Tungsten nanoparticles (WNPs) were incorporated along with polyhydroxybutyrate (PHB), polycaprolactone (PCL), and polyvinylpyrrolidone (PVP) polymers to increase the surface adsorption of WNPs. The physicochemical and in vitro and in vivo imaging properties of PPDO IVCFs with WNPs with single-polymer PHB (W-P) were compared with those of WNPs with polymer blends consisting of PHB, PCL, and PVP (W-PB).

RESULTS

In vitro analyses using PPDO sutures showed enhanced radiopacity with either W-P or W-PB coating, without compromising the inherent physicomechanical properties of the PPDO sutures. W-P- and W-PB-coated IVCFs were deployed successfully into the inferior vena cava of pig models with monitoring by fluoroscopy. At the time of deployment, W-PB-coated IVCFs showed a 2-fold increase in radiopacity compared to W-P-coated IVCFs. Longitudinal monitoring of in vivo IVCFs over a 12-week period showed a drastic decrease in radiopacity at Week 3 for both filters.

CONCLUSIONS

The results highlight the utility of nanoparticles (NPs) and polymers for enhancing radiopacity of medical devices. Different methods of incorporating NPs and polymers can still be explored to improve the effectiveness, safety, and quality of absorbable IVCFs.

Subacute Cutaneous Toxicity with Single-Fraction Electron FLASH RT in Yorkshire Swine

PURPOSE/OBJECTIVE(S)

Information regarding acute/subacute skin toxicity of electron FLASH radiation therapy (RT) is limited. We evaluated short-term safety of electron FLASH for human trials by investigating subacute toxicity compared to conventional dose-rate RT (CONV) in the Yorkshire pig, an animal model known to closely approximate human skin and routinely used for toxicity studies.

MATERIALS/METHODS

Two healthy 50 kg pigs underwent CT imaging for RT treatment planning with field visualization via BBs and tattoos on each dorsolateral flank. Each target received a single fraction of 20, 25 or 30 Gy with FLASH and CONV on opposing sides delivered using a dedicated mobile linear accelerator. FLASH dose rates ranged from 164-245 Gy/sec (12 pulses delivered over 0.122 sec) while the CONV dose rate was set at 0.18 Gy/sec. Doses were verified using thermo- and optically stimulated luminescent dosimeters, and Gafchromic films. We obtained baseline and weekly images up to 98 days post-RT (D98) for blinded toxicity grading by 3 expert radiation oncologists using the modified RTOG radiation dermatitis (RD) scale. We measured erythema and pigmentation indices on those timepoints using a handheld spectrophotometer. We also obtained punch biopsies of targets and non-irradiated controls on D10 and D30 for RNA sequencing and two 6-marker multiplex immunofluorescence analyses of inflammation, immune response, and fibrosis. FLASH and CONV data were compared using repeated measures ANOVA and transcriptomic analyses using DESeq2.

RESULTS

All RT targets developed peak median grade 4 (ulceration, hemorrhage, or necrosis) RD by D84 regardless of FLASH or CONV delivery. However, FLASH targets developed peak RD later than CONV targets after 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D63 vs D42). FLASH induced qualitatively lower mean pigmentation and erythema indices than CONV for all 3 doses. Similarly, peak mean pigmentation indices occurred later with FLASH vs CONV for 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D77 vs D63). However, peak mean erythema indices occurred on the same day for FLASH and CONV (D63 for 20 Gy and D42 for 25 and 30 Gy). Transcriptomic analyses revealed significantly upregulated signals for wound healing (including TGF-beta, cell adhesion and extracellular matrix receptor interaction) and leukocyte infiltration with 20 Gy CONV mostly by D10, while FLASH upregulated those pathways only after 25 or 30 Gy, or by D30, or never at all. Preliminary immunofluorescence data showed FLASH may induce less T cell infiltrate and TGF-beta-expressing macrophages than CONV.

CONCLUSION

Single-fraction electron FLASH resulted in delayed onsets of both subacute cutaneous toxicity and wound healing with leukocytic infiltration signaling than dose-matched CONV based on both subjective and objective metrics of skin injury. Our findings suggest further investigations of optimal dose of electron FLASH for safe clinical translation is warranted, and we have a dose-finding study currently underway.

Image-guided deployment and monitoring of a novel tungsten nanoparticleâ€"infused radiopaque absorbable inferior vena cava filter in pigs

The use of absorbable inferior vena cava filters (IVCFs) constructed with poly-p-dioxanone (PPDO) eliminates risks and complications associated with the use of retrievable metallic filters. Radiopacity of radiolucent PPDO IVCFs can be improved with the incorporation of nanoparticles (NPs) made of high-atomic number materials such as gold and bismuth. In this study, we focused on incorporating tungsten NPs (WNPs), along with polyhydroxybutyrate (PHB), polycaprolactone (PCL), and polyvinylpyrrolidone (PVP) polymers to increase the surface adsorption of the WNPs. We compared the imaging properties of WNPs with single-polymer PHB (W-P) and WNPs with polymer blends consisting of PHB, PCL, and PVP (W-PB). Our in vitro analyses using PPDO sutures showed enhanced radiopacity with either W-P or W-PB coating, without compromising the inherent physico-mechanical properties of the PPDO sutures. We observed a more sustained release of WNPs from W-PB-coated sutures than W-P-coated sutures. We successfully deployed W-P- and W-PB-coated IVCFs into the inferior vena cava of pig models, with monitoring by fluoroscopy. At the time of deployment, W-PB-coated IVCFs showed a 2-fold increase in radiopacity compared to W-P-coated IVCFs. Longitudinal monitoring of in vivo IVCFs over a 12-week period showed a drastic decrease in radiopacity at week 3 for both filters. Results of this study highlight the utility of NPs and polymers for enhancing radiopacity of medical devices; however, different methods of incorporating NPs and polymers can still be explored to improve the efficacy, safety, and quality of absorbable IVCFs.

Stem Cell Theory of Cancer: Origin of Metastasis and Sub-clonality

Metastasis may be the secret weapon cancer uses to dominate and subjugate, to persist and prevail. However, it is no longer a secret when we realize that a stem cell has the same ways and means to fulfill its own omnipotence and accomplish its own omnipresence… and when we realize that a cancer cell has its own version of stem-ness origin and stem-like nature. In this perspective, we discuss whether stem-ness enables metastasis or mutations drive metastasis. We ponder about low-grade versus high-grade tumors and about primary versus metastatic tumors. We wonder about stochasticity and hierarchy in the genesis and evolution of cancer and of metastasis. We postulate that metastasis may hold the elusive code that makes or breaks a stem-cell versus a genetic theory of cancer. We speculate that the vaunted model of multistep carcinogenesis may be in error and needs some belated remodeling and a major overhaul. We propose that subsequent malignant neoplasms from germ cell tumors and donor-derived malignancies in organ transplants are quintessential experiments of nature and by man that may eventually empower us to elucidate a stem-cell origin of cancer and metastasis. Unfortunately, even the best experiments of cancer and of metastasis will be left unfinished, overlooked, or forgotten, when we do not formulate a proper cancer theory derived from pertinent and illuminating clinical observations. Ultimately, there should be no consternations when we realize that metastasis has a stem-cell rather than a genetic origin, and no reservations when we recognize that metastasis has been providing us some of the most enduring tests and endearing proofs to demonstrate that cancer is indeed a stem-cell rather than a genetic disease after all.

Abstract B06: A novel patient-derived orthotopic xenograft model of esophageal adenocarcinoma provides a platform for translational discoveries

Background and Aims: Mouse models of GEJ cancer strive to recapitulate the intratumoral heterogeneity and cellular crosstalk within patient tumors to improve clinical translation. GEJ cancers remain a therapeutic challenge due to a lack of reliable mouse model for preclinical drug testing.

Methods: A novel PDOX was established from GEJ cancer via transabdominal surgical implantation. Patient tumor was compared to subcutaneously implanted patient-derived tumor xenograft (PDX) and PDOX by H&E, immunohistochemistry, and next-generation sequencing. Treatment efficacy studies of radiotherapy were performed.

Results: Mechanical abrasion of mouse GEJ prior to surgical implantation of patient-derived tumor in situ promotes tumor engraftment (100%, n=6). Complete PDOX engraftment was observed with rapid intra- and extraluminal tumor growth as evidenced by magnetic resonance imaging. PDOXs contain fibroblasts, tumor-associated macrophages (TAMs), immune and inflammatory cells, and vascular and lymphatic vessels. Stromal hallmarks of aggressive GEJs are recapitulated in GEJ-PDOX mouse model. PDOXs demonstrates tumor invasion into vasculature and perineural space. Next-generation sequencing revealed loss of heterozygosity (LOH) with very high allelic frequency in NOTCH3, TGFB1, EZH2, and KMT2C in the patient tumor, the subcutaneous PDX, and the PDOX. Immunohistochemical analysis of Her2/neu, p53, and p16 in PDX and PDOX demonstrated maintenance of protein expression found in patient tumors while membranous EGFR overexpression in patient tumor cells was absent in both xenografts. Targeted radiotherapy in this model suggested a decreased in size by 61% according to RECIST, indicating a partial response to radiation therapy.

Conclusions: A GEJ-PDOX model exhibits remarkable fidelity to human disease and captures the precise tissue microenvironment present within the local GEJ architecture, facilitating it as a novel tool in translating findings from such studies. This model can be applied to study metastatic progression and to develop novel therapeutic approaches for the treatment of GEJ cancer.

Note: This abstract was not presented at the conference.

Citation Format: Omkara Veeranki, Zhimin Tong, Alicia Mejia, Anuj Verma, Riham Katkhuda, Roland Bassett, Tae Kim, Jing Wang, Wenhua Lang, Barbara Mino, Luisa Solis, Charles Kingsley, William Norton, Ramesh Tailor, Ji Wu, Sunil Krishnan, Steven Lin, Mariela Blum, Wayne Hofstetter, Jaffer Ajani, Scott Kopetz, Dipen Maru. A novel patient-derived orthotopic xenograft model of esophageal adenocarcinoma provides a platform for translational discoveries [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr B06.

Endobronchial ultrasound-guided injection of NBTXR3 radio-enhancing nanoparticles into mediastinal and hilar lymph nodes: a swine model to evaluate feasibility, injection technique, safety, nanoparticle retention and dispersion

Background

Loco-regionally advanced lung cancer is typically treated with a combination of chemotherapy and radiation therapy, but overall survival and local control remain poor. Radio-enhancing nanoparticles such as NBTXR3 activated by radiotherapy results in increased cell death and potentially an anti-tumor immune response. The goal of this study was to assess the feasibility and safety of endobronchial ultrasound (EBUS)-guided injection of NBTXR3 into mediastinal and hilar lymph nodes (LN), as well as assess nanoparticle retention in the LN post-injection.

Methods

Animals underwent bronchoscopy under general anesthesia with EBUS-guided injection of NBTXR3 into hilar and mediastinal LN. LN and injection volumes were calculated based on pre-injection computed tomography (CT) scans. CT scans were repeated at 5 min, 30 min, and 8 days post-injection. Blood-draws were also obtained at baseline and post-injection. Animals were then housed, monitored, and sacrificed 8 days post-injection. Necropsy was then performed with gross and histologic analysis of LN.

Results

A total of 20 LN were injected in 5 pigs (4 LN per animal). Nanoparticles were retained in 100% of LN at 30 min, and 90% of LN at 8 days. Extravasation of nanoparticles was seen in 4 out of the 20 LN. There were no cases of nanoparticle embolization visible by CT in distant organs. Small air-bubbles were introduced in the targets and surrounding tissue in 3 out of 20 LN. Of note, at 8 days, none of these air-bubbles were present on CT scan. There were no intra-procedural or post-procedural complications in either CT scans or necropsy findings. Pigs remained clinically stable and neither laboratory values nor necropsy showed evidence of inflammation.

Conclusions

EBUS-guided injection of NBTXR3 radio-enhancing nanoparticles can be safely performed achieving a high rate of nanoparticle retention, low extravasation, and no visible nanoparticle embolization.

Current practice of anticoagulant in the treatment of splanchnic vein thrombosis secondary to acute pancreatitis

BACKGROUND

Severe acute pancreatitis is a common diagnosis in emergency general surgery and can be a cause of significant morbidity and mortality. A consequence of severe acute pancreatitis is thrombus in the splanchnic veins. These thrombi can potentially lead to bowel ischemia or hepatic failure. However, another complication of severe acute pancreatitis is retroperitoneal bleeding. At this time, it is unclear if treating patients for splanchnic vein thrombosis in the context of severe acute pancreatitis is associated with any outcome benefit. A systematic review might clarify this question.

DATA SOURCES

A two-fold search strategy (one broad and one precise) looked at all published literature. The review was registered on PROSPERO (ID: CRD42018102705). MEDLINE, EMBASE, PubMed, Cochrane and Web of Science databases were searched and potentially relevant papers were reviewed independently by two researchers. Any disagreement was reviewed by a third independent researcher. Primary outcome was reestablishment of flow in the thrombosed vein versus bleeding complications.

RESULTS

Of 1462 papers assessed, a total of 16 papers were eligible for inclusion. There were no randomized controlled trials, 2 were case series, 5 retrospective single-center studies and 9 case reports. There were a total of 198 patients in these studies of whom 92 (46.5%) received anticoagulation therapy. The rates of recanalization of veins in the treated and non-treated groups was 14% and 11% and bleeding complications were 16% and 5%, respectively. However, the included studies were too heterogeneous to undertake a meta-analysis.

CONCLUSIONS

The systematic review highlights the lack evidence addressing this clinical question. Therefore a randomized controlled trial would be appropriate to undertake.

A novel patient-derived orthotopic xenograft model of esophageal adenocarcinoma provides a platform for translational discoveries

Mouse models of gastroesophageal junction (GEJ) cancer strive to recapitulate the intratumoral heterogeneity and cellular crosstalk within patient tumors to improve clinical translation. GEJ cancers remain a therapeutic challenge due to the lack of a reliable mouse model for preclinical drug testing. In this study, a novel patient-derived orthotopic xenograft (PDOX) was established from GEJ cancer via transabdominal surgical implantation. Patient tumor was compared to subcutaneously implanted patient-derived tumor xenograft (PDX) and PDOX by Hematoxylin and Eosin staining, immunohistochemistry and next-generation sequencing. Treatment efficacy studies of radiotherapy were performed. We observed that mechanical abrasion of mouse GEJ prior to surgical implantation of a patient-derived tumor in situ promotes tumor engraftment (100%, n=6). Complete PDOX engraftment was observed with rapid intra- and extraluminal tumor growth, as evidenced by magnetic resonance imaging. PDOXs contain fibroblasts, tumor-associated macrophages, immune and inflammatory cells, vascular and lymphatic vessels. Stromal hallmarks of aggressive GEJ cancers are recapitulated in a GEJ PDOX mouse model. PDOXs demonstrate tumor invasion into vasculature and perineural space. Next-generation sequencing revealed loss of heterozygosity with very high allelic frequency in NOTCH3, TGFB1, EZH2 and KMT2C in the patient tumor, the subcutaneous PDX and the PDOX. Immunohistochemical analysis of Her2/neu (also known as ERBB2), p53 (also known as TP53) and p16 (also known as CDKN2A) in PDX and PDOX revealed maintenance of expression of proteins found in patient tumors, but membranous EGFR overexpression in patient tumor cells was absent in both xenografts. Targeted radiotherapy in this model suggested a decrease in size by 61% according to Response Evaluation Criteria in Solid Tumors (RECIST), indicating a partial response to radiation therapy. Our GEJ PDOX model exhibits remarkable fidelity to human disease and captures the precise tissue microenvironment present within the local GEJ architecture, providing a novel tool for translating findings from studies on human GEJ cancer. This model can be applied to study metastatic progression and to develop novel therapeutic approaches for the treatment of GEJ cancer.

This article has an associated First Person interview with the first author of the paper.

Editor's choice: The patient-derived orthotopic xenograft model of gastroesophageal adenocarcinoma maintains the morphological and molecular characteristics despite being highly heterogeneous, emphasizing its use as a powerful investigational platform to evaluate new therapies.

Novel therapeutic interventions for p53-altered tumors through manipulation of its family members, p63 and p73

TP53 is highly mutated in human cancers, thus targeting this tumor suppressor pathway is highly desirable and will impact many cancer patients. (1,2) Therapeutic strategies to reactivate the p53-pathway have been challenging, (3,4) and no effective treatment exists. (5) We utilized the p53-family members, p63 and p73, which are not frequently mutated in cancer, to treat p53-defective cancers. The N-terminal splice variants of p63 and p73 are denoted as the TA and ΔN isoforms. We recently demonstrated that deletion of either ΔNp63 or ΔNp73 in p53-deficient mouse tumors results in tumor regression mediated by metabolic programming. Using this strategy, we identified pramlintide, a synthetic analog of amylin, as an effective treatment for p53 deficient and mutant tumors. Here, we show the utility of using pramlintide, as a potential cancer preventive option for p53-deficient tumors in mouse models. Additionally, we found that in vivo inhibition of both ΔNp63 and ΔNp73 in combination accelerates tumor regression and increases survival of p53-deficient mice. We report that inhibition of both ΔNp63 and ΔNp73 in combination results in upregulation of 3 key metabolic regulators, IAPP, GLS2, and TIGAR resulting in an increase in apoptosis and tumor regression in ΔNp63/ΔNp73/p53 deficient thymic lymphomas. These data highlight the value of generating inhibitors that will simultaneously target ΔNp63 and ΔNp73 to treat cancer patients with alterations in p53.

ΔNp63/DGCR8-Dependent MicroRNAs Mediate Therapeutic Efficacy of HDAC Inhibitors in Cancer

ΔNp63 is an oncogenic member of the p53 family and acts to inhibit the tumor-suppressive activities of the p53 family. By performing a chemical library screen, we identified histone deacetylase inhibitors (HDACi) as agents reducing ΔNp63 protein stability through the E3 ubiquitin ligase, Fbw7. ΔNp63 inhibition decreases the levels of its transcriptional target, DGCR8, and the maturation of let-7d and miR-128, which we found to be critical for HDACi function in vitro and in vivo. Our work identified Fbw7 as a predictive marker for HDACi response in squamous cell carcinomas and lymphomas, and unveiled let-7d and miR-128 as specific targets to bypass tumor resistance to HDACi treatment.

Abstract 3975: Pharmacologic inhibition of the ΔNp63/DGCR8 axis as a novel therapeutic strategy for p53-deficient and mutant tumors

The p63 gene is a member of the p53 family, whose transcription is driven by two alternative promoters, allowing the expression of two distinct isoforms: TAp63 and ΔNp63. In order to determine their roles in tumorigenesis, our group has generated isoform-specific knockout mouse models. TAp63 was found to be a pivotal tumor and metastasis suppressor, whose function is achieved by the regulation of the miRNA biogenesis pathway in a Dicer dependent way. ΔNp63 was shown to be a master regulator of the differentiation of epithelial tissues, such as the epidermis. Np63 is indeed able to directly induce the expression of DGCR8, a co-factor essential in modulating miRNA biogenesis, sustaining in this manner a proper epidermal differentiation. Accordingly, ΔNp63 knockout mice die shortly after birth because of developmental defects. In addition to characterize its role in skin development, our group has recently demonstrated that ΔNp63 may act as an oncogene by counteracting TAp63 tumor suppressive activities in vivo: specific deletion of ΔNp63 in p53−/− thymic lymphomas caused TAp63 reactivation and consequent tumor shrinkage.

Based on all these findings, we hypothesized that ΔNp63 might support tumor formation not only by inhibiting TAp63, but also by affecting miRNA maturation in a DGCR8 dependent manner. In line with this hypothesis, we deem that the inhibition of the ΔNp63/DGCR8 axis might be crucial to curb ΔNp63 tumor promoting activities. To this end, we screened a drug library of more than 850 FDA approved compounds looking for inhibitors of the ΔNp63/DGCR8 axis. We found several small molecules that were able to reduce ΔNp63 protein stability and, as a result, to decrease the expression levels of its target gene DGCR8 and that of a specific set of miRNAs, whose biosynthesis is DGCR8-dependent. On the contrary, the levels of DGCR8-independent miRNAs were not affected by the drug treatments. In agreement with our hypothesis, curbing the ΔNp63/DGCR8 axis by either these drugs or inhibitors against the identified miRNAs, reduced cell viability of different cancer cell types of both murine and human origin, without affecting that of normal cells. In vivo analyses of these compounds as well as of these miRNA inhibitors have showed their efficacy in counteracting tumor formation and progression in mice. In summary, we believe that the in vitro and in vivo characterization of the ΔNp63/DGCR8 axis will provide a novel and effective strategy to target tumors relying on ΔNp63 for their expansion, especially the most therapeutically challenging ones devoid of a functional tumor suppressor p53.

Citation Format: Marco Napoli, Avinashnarayan Venkatanarayan, Payal Raulji, Hussein A. Abbas, William Norton, Anil K. Sood, Gabriel Lopez-Berestein, Kenneth Y. Tsai, Cristian Coarfa, Preethi H. Gunaratne, Elsa R. Flores. Pharmacologic inhibition of the ΔNp63/DGCR8 axis as a novel therapeutic strategy for p53-deficient and mutant tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3975. doi:10.1158/1538-7445.AM2015-3975

Chondrocytes transdifferentiate into osteoblasts in endochondral bone during development, postnatal growth and fracture healing in mice

One of the crucial steps in endochondral bone formation is the replacement of a cartilage matrix produced by chondrocytes with bone trabeculae made by osteoblasts. However, the precise sources of osteoblasts responsible for trabecular bone formation have not been fully defined. To investigate whether cells derived from hypertrophic chondrocytes contribute to the osteoblast pool in trabecular bones, we genetically labeled either hypertrophic chondrocytes by Col10a1-Cre or chondrocytes by tamoxifen-induced Agc1-CreERT2 using EGFP, LacZ or Tomato expression. Both Cre drivers were specifically active in chondrocytic cells and not in perichondrium, in periosteum or in any of the osteoblast lineage cells. These in vivo experiments allowed us to follow the fate of cells labeled in Col10a1-Cre or Agc1-CreERT2 -expressing chondrocytes. After the labeling of chondrocytes, both during prenatal development and after birth, abundant labeled non-chondrocytic cells were present in the primary spongiosa. These cells were distributed throughout trabeculae surfaces and later were present in the endosteum, and embedded within the bone matrix. Co-expression studies using osteoblast markers indicated that a proportion of the non-chondrocytic cells derived from chondrocytes labeled by Col10a1-Cre or by Agc1-CreERT2 were functional osteoblasts. Hence, our results show that both chondrocytes prior to initial ossification and growth plate chondrocytes before or after birth have the capacity to undergo transdifferentiation to become osteoblasts. The osteoblasts derived from Col10a1-expressing hypertrophic chondrocytes represent about sixty percent of all mature osteoblasts in endochondral bones of one month old mice. A similar process of chondrocyte to osteoblast transdifferentiation was involved during bone fracture healing in adult mice. Thus, in addition to cells in the periosteum chondrocytes represent a major source of osteoblasts contributing to endochondral bone formation in vivo.

IAPP-driven metabolic reprogramming induces regression of p53-deficient tumours in vivo

TP53 is commonly altered in human cancer, and Tp53 reactivation suppresses tumours in vivo in mice (TP53 and Tp53 are also known as p53). This strategy has proven difficult to implement therapeutically, and here we examine an alternative strategy by manipulating the p53 family members, Tp63 and Tp73 (also known as p63 and p73, respectively). The acidic transactivation-domain-bearing (TA) isoforms of p63 and p73 structurally and functionally resemble p53, whereas the ΔN isoforms (lacking the acidic transactivation domain) of p63 and p73 are frequently overexpressed in cancer and act primarily in a dominant-negative fashion against p53, TAp63 and TAp73 to inhibit their tumour-suppressive functions. The p53 family interacts extensively in cellular processes that promote tumour suppression, such as apoptosis and autophagy, thus a clear understanding of this interplay in cancer is needed to treat tumours with alterations in the p53 pathway. Here we show that deletion of the ΔN isoforms of p63 or p73 leads to metabolic reprogramming and regression of p53-deficient tumours through upregulation of IAPP, the gene that encodes amylin, a 37-amino-acid peptide co-secreted with insulin by the β cells of the pancreas. We found that IAPP is causally involved in this tumour regression and that amylin functions through the calcitonin receptor (CalcR) and receptor activity modifying protein 3 (RAMP3) to inhibit glycolysis and induce reactive oxygen species and apoptosis. Pramlintide, a synthetic analogue of amylin that is currently used to treat type 1 and type 2 diabetes, caused rapid tumour regression in p53-deficient thymic lymphomas, representing a novel strategy to target p53-deficient cancers.

Towards a comprehensive catalog of zebrafish behavior 1.0 and beyond

Zebrafish (Danio rerio) are rapidly gaining popularity in translational neuroscience and behavioral research. Physiological similarity to mammals, ease of genetic manipulations, sensitivity to pharmacological and genetic factors, robust behavior, low cost, and potential for high-throughput screening contribute to the growing utility of zebrafish models in this field. Understanding zebrafish behavioral phenotypes provides important insights into neural pathways, physiological biomarkers, and genetic underpinnings of normal and pathological brain function. Novel zebrafish paradigms continue to appear with an encouraging pace, thus necessitating a consistent terminology and improved understanding of the behavioral repertoire. What can zebrafish 'do', and how does their altered brain function translate into behavioral actions? To help address these questions, we have developed a detailed catalog of zebrafish behaviors (Zebrafish Behavior Catalog, ZBC) that covers both larval and adult models. Representing a beginning of creating a more comprehensive ethogram of zebrafish behavior, this effort will improve interpretation of published findings, foster cross-species behavioral modeling, and encourage new groups to apply zebrafish neurobehavioral paradigms in their research. In addition, this glossary creates a framework for developing a zebrafish neurobehavioral ontology, ultimately to become part of a unified animal neurobehavioral ontology, which collectively will contribute to better integration of biological data within and across species.

Abstract 2331: Deletion of ΔNp63 and ΔNp73 in p53 deficient mice results in TAp63 and TAp73 compensation of p53 tumor suppression in vivo

p53 tumor suppressor undergoes mutational loss in majority of cancers contributing to tumor formation. Therapeutic strategies are aimed towards p53 overexpression in tumors or to identify targets that compensate for p53-functional loss. p63 & p73, share structural similarities to p53, making them excellent candidates for therapeutic compensation of p53. Unlike p53, p63 and p73 do not undergo mutational loss and their role in tumorigenesis is being delineated. p63 and p73 have two major isoforms, the transactivation (TA), with activities similar to p53 and the delta (Δ)N- isoform with oncogenic functions. Inhibition of TAp63 and TAp73 is observed in cancers as a consequence of overexpression of ΔN isoforms of p63 and p73. In disparity, recent studies report, tumor suppressive properties of ΔNp63 and ΔNp73 in activating genes involved in DNA repair and apoptosis.

To define the functional roles of ΔNp63 and ΔNp73 in cancer, mouse models targeting the ΔN isoforms were generated. We observed that, ΔNp63+/- and ΔNp73−/− mice on a p53−/− background had lower thymic lymphoma incidence compared to the p53−/− mice. I found TAp63 and TAp73 up regulated in the double mutant mice that correspond with an increase in p53-downstream apoptotic (PUMA, Noxa, BAX) and cell cycle targets (p21, p16, PML). This suggests that ablation of ΔN isoforms mediate TAp63 and TAp73 up regulation inducing apoptosis or cell cycle arrest by activation of p53-downstream targets. To further demonstrate this, I ablated ΔNp63 and ΔNp73 in vivo in p53−/- mice thymic lymphoma by administering adenoviral-CRE specifically to the thymus. The CRE-treated mice had a significant thymic lymphoma regression within 3 weeks as imaged by MRI in comparison to the mock-treated mouse cohorts. Additionally, RNA-Seq analysis from CRE-treated versus untreated mice, has identified novel metabolic genes with apoptotic or cell-cycle functions. We further report, ΔNp63 and ΔNp73 to bind to promoter site of TAp63 and TAp73 by chromatin immunoprecipitation (ChIP). This supports the notion that ablation of ΔN isoforms of p63 and p73 restores the function of TAp63 and TAp73 thus compensating for p53-tumor suppressive function in vivo. To test, if ablation of ΔN isoforms reduces tumorigenesis in human cancers, ΔNp63 and ΔNp73 were knocked down in human cancer cell lines were p53 expression was ablated or mutated. TAp63 and TAp73 were upregulated in ΔNp63/ΔNp73 knock down human cancer cell lines. However, induction of apoptosis or cell-cycle arrest was observed in p53-deleted cancer cell lines in comparison to the p53-mutated cell lines. This highlights the co-repressive effect of mutant p53, preventing activation of TAp63/TAp73 downstream targets. Current work is aimed towards overcoming mutant p53 effect in these cancer cell lines. Thus, targeting the ΔNp63/ΔNp73 compensates for p53-functional loss mediating tumor suppression.

Citation Format: Avinashnarayan Venkatanarayan, Deepavali Chakravarti, Xiaohua Su, Santosh Sandur, Lingzhi Liu, Eliot Fletcher Sananikone, Payal Raulji, Cristian Coarfa, William Norton, Preethi Gunaratne, Elsa Renee Flores. Deletion of ΔNp63 and ΔNp73 in p53 deficient mice results in TAp63 and TAp73 compensation of p53 tumor suppression in vivo. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2331. doi:10.1158/1538-7445.AM2013-2331

Report of the Second European Zebrafish Principal Investigator Meeting in Karlsruhe, Germany, March 21-24, 2012

The second European Zebrafish Principal Investigator (PI) Meeting was held in March, 2012, in Karlsruhe, Germany. It brought together PIs from all over Europe who work with fish models such as zebrafish and medaka to discuss their latest results, as well as to resolve strategic issues faced by this research community. Scientific discussion ranged from the development of new technologies for working with fish models to progress in various fields of research such as injury and repair, disease models, and cell polarity and dynamics. This meeting also marked the establishment of the European Zebrafish Resource Centre (EZRC) at Karlsruhe that in the future will serve as an important focus and community resource for zebrafish- and medaka-based research.

Zebrafish 20β-hydroxysteroid dehydrogenase type 2 is important for glucocorticoid catabolism in stress response

Stress, the physiological reaction to a stressor, is initiated in teleost fish by hormone cascades along the hypothalamus-pituitary-interrenal (HPI) axis. Cortisol is the major stress hormone and contributes to the appropriate stress response by regulating gene expression after binding to the glucocorticoid receptor. Cortisol is inactivated when 11β-hydroxysteroid dehydrogenase (HSD) type 2 catalyzes its oxidation to cortisone. In zebrafish, Danio rerio, cortisone can be further reduced to 20β-hydroxycortisone. This reaction is catalyzed by 20β-HSD type 2, recently discovered by us. Here, we substantiate the hypothesis that 20β-HSD type 2 is involved in cortisol catabolism and stress response. We found that hsd11b2 and hsd20b2 transcripts were up-regulated upon cortisol treatment. Moreover, a cortisol-independent, short-term physical stressor led to the up-regulation of hsd11b2 and hsd20b2 along with several HPI axis genes. The morpholino-induced knock down of hsd20b2 in zebrafish embryos revealed no developmental phenotype under normal culture conditions, but prominent effects were observed after a cortisol challenge. Reporter gene experiments demonstrated that 20β-hydroxycortisone was not a physiological ligand for the zebrafish glucocorticoid or mineralocorticoid receptor but was excreted into the fish holding water. Our experiments show that 20β-HSD type 2, together with 11β-HSD type 2, represents a short pathway in zebrafish to rapidly inactivate and excrete cortisol. Therefore, 20β-HSD type 2 is an important enzyme in stress response.

The ADHD-susceptibility gene lphn3.1 modulates dopaminergic neuron formation and locomotor activity during zebrafish development

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, increased impulsivity and emotion dysregulation. Linkage analysis followed by fine-mapping identified variation in the gene coding for Latrophilin 3 (LPHN3), a putative adhesion-G protein-coupled receptor, as a risk factor for ADHD. In order to validate the link between LPHN3 and ADHD, and to understand the function of LPHN3 in the etiology of the disease, we examined its ortholog lphn3.1 during zebrafish development. Loss of lphn3.1 function causes a reduction and misplacement of dopamine-positive neurons in the ventral diencephalon and a hyperactive/impulsive motor phenotype. The behavioral phenotype can be rescued by the ADHD treatment drugs methylphenidate and atomoxetine. Together, our results implicate decreased Lphn3 activity in eliciting ADHD-like behavior, and demonstrate its correlated contribution to the development of the brain dopaminergic circuitry.

Discovery of a novel enzyme mediating glucocorticoid catabolism in fish: 20beta-hydroxysteroid dehydrogenase type 2

Hydroxysteroid dehydrogenases (HSDs) are involved in metabolism and pre-receptor regulation of steroid hormones. While 17beta-HSDs and 11beta-HSDs are extensively studied in mammals, only few orthologs are characterized in fish. We discovered a novel zebrafish HSD candidate closely related to 17beta-HSD types 3 and 12, which has orthologs in other species. The enzyme catalyzes the conversion of cortisone to 20beta-hydroxycortisone identified by LC-MS/MS. We named the new enzyme 20beta-HSD type 2. All 20beta-HSD type 2 orthologs localize in the endoplasmic reticulum. Zebrafish 20beta-HSD type 2 is expressed during embryonic development showing the same expression pattern as 11beta-HSD type 2 known to oxidize cortisol to cortisone. In adult tissues 20beta-HSD type 2 shows a ubiquitous expression pattern with some minor sex-specific differences. In contrast to other enzymes metabolizing C21-steroids and being mostly involved in reproduction we propose that novel type 2 20beta-HSDs in teleost fish are important enzymes in cortisol catabolism.

Adult zebrafish as a model organism for behavioural genetics

Recent research has demonstrated the suitability of adult zebrafish to model some aspects of complex behaviour. Studies of reward behaviour, learning and memory, aggression, anxiety and sleep strongly suggest that conserved regulatory processes underlie behaviour in zebrafish and mammals. The isolation and molecular analysis of zebrafish behavioural mutants is now starting, allowing the identification of novel behavioural control genes. As a result of this, studies of adult zebrafish are now helping to uncover the genetic pathways and neural circuits that control vertebrate behaviour.

Fgf10 regulates hepatopancreatic ductal system patterning and differentiation

During organogenesis, the foregut endoderm gives rise to the many different cell types that comprise the hepatopancreatic system, including hepatic, pancreatic and gallbladder cells, as well as the epithelial cells of the hepatopancreatic ductal system that connects these organs together and with the intestine. However, the mechanisms responsible for demarcating ducts versus organs are poorly understood. Here, we show that Fgf10 signaling from the adjacent mesenchyme is responsible for refining the boundaries between the hepatopancreatic duct and organs. In zebrafish fgf10 mutants, the hepatopancreatic ductal epithelium is severely dysmorphic, and cells of the hepatopancreatic ductal system and adjacent intestine misdifferentiate toward hepatic and pancreatic fates. Furthermore, Fgf10 also functions to prevent the differentiation of the proximal pancreas and liver into hepatic and pancreatic cells, respectively. These data shed light onto how the multipotent cells of the foregut endoderm, and subsequently those of the hepatopancreatic duct, are directed toward different organ fates.

Urine amino and organic acids analysis in developmental delay or intellectual disability

OBJECTIVES

To determine the proportion of urine amino and organic acids screening tests (UMS) undertaken for patients referred with developmental delay or intellectual disability (DD/ID), and within the group with DD/ID, to determine the diagnostic yield, the proportion of diagnoses with a therapy and the associated recurrence risks.

METHODS

A retrospective review of request forms and results of UMS, in individuals older than 28 days, referred to the Women's and Children's Hospital, North Adelaide, between 1 January 1992 and 31 December 1998 was carried out. Urine was analysed by ion exchange chromatography (amino acids), gas chromatography/mass spectrometry (organic acids), colorimetric assay (orotic acid) and stable isotope-dilution mass spectrometry (trimethylamine).

RESULTS

A total of 3316 samples were received, 1447 being from patients with DD/ID. A diagnosis was determined for 1.8% of all referrals. For patients with DD/ID, the diagnostic yield was 1.1%, with a similar yield for isolated DD/ID and DD/ID with other features (9/828 vs 7/619; chi2 = 0.006; P = 0.93). Specific therapies were available for 69% of diagnoses associated with DD/ID and 87.5% had known Mendelian or mitochondrial inheritance.

CONCLUSION

Urine metabolic screening is an important part of the evaluation of children with DD/ID as it can enable families to make reproductive decisions and children to receive appropriate therapy early.

RS2: a sugar beet gene related to the latex allergen Hev b 5 family

A novel gene (RS2) has been isolated from a Beta vulgaris (cv. Regina) cDNA library. The expression of this gene was enhanced in the mature storage organ as compared to leaf tissue. The protein encoded by this gene was found to be alanine- and glutamic acid-rich and it resembles members of the latex allergen Hev b 5 family.

Prevalence of psychologic impairment in an advanced-age population

Interviews were conducted in the homes of 200 persons aged 80 years or older; 100 lived in Vancouver and 100 in Victoria, B. C. Between 15 and 27 per cent showed psychologic impairment, as measured by self-reporting of symptoms, including use of prescribed psychotropic drugs. A comparison of those who were psychologically impaired with those who were psychologically healthy demonstrated that accidents, eye problems, and dearth of social contacts were significantly associated with the former group. In 74 per cent of the sample, activities were restricted in varying degrees because of health problems, and there was a surprising degree of social isolation. On the Social Interaction Index, low scores were significantly more common among the psychologically impaired, and a similar relationship between poor physical health and social isolation was demonstrated with a multiple regression analysis. The findings suggest that poor social interaction, particularly, and poor health may be predictors of psychologic distress. Extended family support is weakening, and planned programs are needed to improve the lifestyles of the aged and to prevent loneliness and alienation.

Medical and social factors associated with psychological distress in a sample of community aged

Two hundred persons over 80 in two urban communities were interviewed. Of those interviewed, 21% evidenced psychological impairment as defined by the presence of at least one of the following self-report symptoms: 1) depression; 2) periods of inability to function; 3) suicidal ideation; 4) alcohol problems and 5) use of psychotropic medication. A profile of the psychologically impaired group compared to the psychologically healthy showed that accidents (mostly falls), eye problems and few social contacts were significantly associated with impairment. Approximately 75% had some restrictions on activity due to physical health problems. Social isolation was marked: 54% either had no children or saw them less than once a month; 38% visited with close friends or relatives less than once a month; 19% were rated as having very little or no social support; and 23% socialized beyond the household less than once a week. Social interaction was the strongest predictor of psychological wellbeing (Affect Balance Scale) in a multiple regression analysis that included physical health and socioeconomic variables. Questions about service needs and utilization indicated unmet needs in the areas of transportation, house maintenance, medical services, and a regular visiting service.

Intracellular iron-binding macromolecules in HeLa cells

The concentration of the iron-chelating agent, desferrioxamine (Desferal), that just inhibits iron entry into HeLa cells is also the concentration that inhibits DNA synthesis. As a first step in clarification of the mechanism whereby iron may partake in DNA synthesis, we have partially characterized several of the intracellular iron-binding sites. Most cytoplasmic iron appears to be bound to a polysaccharide containing glucose that sediments at about 32 S. Nucleolar iron is bound to a single protein, the mobility of which is independent of the concentration of sodium dodecyl sulfate in an acrylamide gel. In contrast the pattern and mobility of nuclear iron, other than nucleolar, is heterogeneous and markedly affected by the concentration of sodium dodecyl sulfate. The evidence suggests that nuclear iron is bound to protein through one or more intermediate(s).

The local response in the guinea-pig to self and non-self proteins

Foreign proteins have been compared with their corresponding isologous and autologous proteins with respect to their capacity to induce inflammatory reactions at the site of injection in the skin. In contrast to the foreign proteins, which consistently produced mild reactions which were morphologically similar to the delayed hypersensitivity reaction, autologous and isologous proteins failed to induce local accumulations of inflammatory cells. The capacity of cells at the inflammatory site to phagocytoze heterologous and isologous ferritin was investigated in the electron microscope, and no qualitative differences were noted. The results are interpreted as evidence for the existence of a local mechanism capable of differentiating between foreign and autologous protein. The possible significance and role of such a mechanism is discussed.