Psoralen: a narrative review of current and future therapeutic uses

Psoralen is a family of naturally occurring photoactive compounds found in plants that acquire potential cytotoxicity when activated by specific frequencies of electromagnetic waves. Psoralens penetrate the phospholipid cellular membranes and insert themselves between the pyrimidines of deoxyribonucleic acid (DNA). Psoralens are initially biologically inert and acquire photoreactivity when exposed to certain classes of electromagnetic radiation, such as ultraviolet light. Once activated, psoralens form mono- and di-adducts with DNA, leading to marked cell apoptosis. This apoptotic effect is more pronounced in tumor cells due to their high rate of cell division. Moreover, photoactivated psoralen can inhibit tyrosine kinase signaling and influence the immunogenic properties of cells. Thus, the cytotoxicity of photoactivated psoralen holds promising clinical applications from its immunogenic properties to potential anti-cancer treatments. This narrative review aims to provide an overview of the current understanding and research on psoralen and to explore its potential future pharmacotherapeutic benefits in specific diseases.

Giant cell tumor of bone in the pediatric population: a retrospective study highlighting cases of metaphyseal only location and increased local recurrence rates in skeletally immature patients

OBJECTIVE

To describe the presentation of giant cell tumors (GCT) of the bone in the pediatric population to (1) improve the differential diagnosis of pediatric bone tumors and (2) identify the origin of GCT. Understanding the origin of bone tumors assists in establishing appropriate diagnoses and recommending treatment options. This is particularly important in children, where evaluating the need for invasive procedures is balanced with the desire to avoid overtreatment. GCT have historically been considered epiphyseal lesions with potential metaphyseal extension. Therefore, GCT may be inappropriately excluded from the differential diagnosis of metaphyseal lesions in the skeletally immature.

MATERIALS AND METHODS

We identified 14 patients from 1981 to 2021 at a single institution who had histologic confirmation of GCT and were less than 18 years old at diagnosis. Patient characteristics, tumor location, surgical treatment, and local recurrence rates were collected.

RESULTS AND CONCLUSIONS

Ten (71%) patients were female. Eleven (78.6%) were epiphysiometaphyseal (1 epiphyseal, 4 metaphyseal, 6 epiphysiometaphyseal). Five patients had an open adjacent physis, of which three (60%) had tumors confined solely to the metaphysis. Of the five patients with open physis, four (80%) developed local recurrence while only one patient (11%) with a closed physis had local recurrence (p value = 0.0023). Our results illustrate that for the skeletally immature, GCT can (and in our results more commonly did) occur in the metaphyseal location. These findings suggest that GCT should be included in the differential diagnosis of primary metaphyseal-only lesions in the skeletally immature.

Self-Healing of Hyaluronic Acid to Improve In Vivo Retention and Function

Convergent advances in the field of soft matter, macromolecular chemistry, and engineering have led to the development of biomaterials that possess autonomous, adaptive, and self-healing characteristics similar to living systems. These rationally designed biomaterials can surpass the capabilities of their parent material. Herein, the modification of hyaluronic acid (HA) to exhibit self-healing properties is described, and its physical and biological function both in vitro and in vivo is studied. The in vitro findings showed that self-healing HA designed to undergo self-repair improves lubrication, enhances free radical scavenging, and attenuates enzymatic degradation compared to unmodified HA. Longitudinal imaging following intraarticular injection of self-healing HA shows improved in vivo retention despite its low molecular weight. Concomitant with these functions, intraarticular injection of self-healing HA mitigates anterior cruciate ligament injury-mediated cartilage degeneration in rodents. This proof-of-concept study shows how incorporation of functional properties such as self-healing can be used to surpass the existing capabilities of biolubricants.

Effects of unilaterally restricted carpal range of motion on kinematic gait analysis of the dog

Decreased carpal range of motion is a common sequel to both disease and injury of the canine carpus; it is also encountered following therapeutic endeavours such as taping, bandaging, and arthrodesis. It was the aim of this study to define alterations of movement in dogs with artificially restricted carpal range of motion (ROM) by use of non-invasive, two-dimensional, computer-assisted kinematic gait analysis. Carpal taping was performed using strips of five centimetre adhesive porous bandage tape placed in circumferential, overlapping strips from mid-radius to just proximal to the metacarpal pad. Significant differences (p < 0.05) in angular displacement were observed, not only in the motion-restricted carpus, but also in the ipsilateral shoulder and contralateral stifle, demonstrating the need for monitoring of other joints when carpal ROM is restricted unilaterally either due to pathology, coaptation or arthrodesis.

Abstract PR09: Modeling the tumor microenvironment in sarcoma: The impact on MPNST biology and chemotherapeutic response

NF1 haploinsufficiency is a hallmark of neurofibromatosis Type 1 and is critical for neurofibroma development. The role of the supporting stroma (endothelial cells, immune cells, fibroblasts, etc.) in the development of patient neurofibromas is well established. However, the impact of NF1 haploinsufficiency on MPNST biology is less clear. Sporadic MPNSTs arise in patients with NF1 wild-type stroma (NF1 +/+), while NF1-associated MPNSTs arise in neurofibromatosis patients with NF1 haploinsufficient stroma (NF1 -/+). Patients with NF1-associated MPNSTs have worse outcome than patients with sporadic MPNSTs, but the cause of this difference is under debate. To define the impact of stromal genetics on tumor biology, we have developed unique mouse models that reflect the genetics of patient-associated MPNSTs.

Using paired littermate mice, we model the genetic status of NF1 in the tumor microenvironment of different MPNST patient populations. We use Adenovirus-Cre injections to generate MPNSTs in NF1 Flox/Flox; CDKN2A Flox/Flox and NF1 Null/Flox; CDKN2A Flox/Flox paired littermate mice to model tumors from NF1 wild-type and NF1-assoicated patients, respectively. We find that NF1 haploinsufficiency (NF1 +/- stroma) accelerates tumor onset, which is accompanied by an increase in immune cells comprising CD11B+ cells, monocytes, and mast cells. Furthermore, mast cells are also enriched in human NF1-associated MPNSTs. We used these mouse models in a preclinical trial to examine how the tumor microenvironment influences response to multiagent chemotherapy and found that the stromal NF1 status does not impact the response of MPNSTs to chemotherapy. Taken together, these studies help clarify the role of the NF1 haploinsufficient tumor microenvironment in MPNSTs.

This abstract is also being presented as Poster B15.

Citation Format: Rebecca Dodd, Chang-Lung Lee, Mary Overton, Wesley Huang, William Eward, Davis Ingram, Diana Cordona, Alexander Lazar, David Kirsch. Modeling the tumor microenvironment in sarcoma: The impact on MPNST biology and chemotherapeutic response [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr PR09.

Abstract 2810: Using CRISPR/Cas9 to generate primary soft tissue sarcoma in genetically engineered and wild-type mice

Genetically engineered mouse models (GEMMs) that employ site-specific recombinase (SSR) technology are important tools for pre-clinical studies, but this approach is costly and time-consuming. Here, we show that the CRISPR/Cas9 system can be used to efficiently complement existing GEMMs of sarcoma and generate primary sarcomas in wild type mice. Mice with the genotype KrasLSL-G12D/+; Rosa26LSL-Cas9-EGFP/+ received intramuscular delivery of an adenovirus expressing Cre recombinase and a single guide RNA (sgRNA) targeting Trp53. Cre-mediated expression of oncogenic Kras and Cas9, in combination with CRISPR/Cas9-mediated knockout of Trp53, was sufficient to generate primary soft tissue sarcomas. These tumors arose with kinetics similar to those generated using the Cre-loxP system to activate oncogenic Kras and delete Trp53 alleles. Additionally, we injected an adenovirus containing Cas9 and sgRNAs targeting Nf1 and Trp53 into the sciatic nerve of wild type mice. These mice formed malignant peripheral nerve sheath tumors (MPNSTs) in the same timeframe as MPNSTs generated using the Cre-loxP system to delete Nf1 and Ink4a/Arf alleles in GEMMs. These data demonstrate that CRISPR/Cas9 can be used to generate soft tissue sarcomas in wild type mice. Moreover, these results suggest that this technology can complement existing GEMMs for rapid assessment of tumor-modifying genes. These tools should decrease the time and expense associated with employing autochthonous mouse models of sarcoma for preclinical research.

Citation Format: Jianguo Huang, Mark Chen, Melodi J. Whitley, Hsuan-Cheng Kuo, Andrea Walens, Yvonne M. Mowery, David V. Mater, William Eward, Diana M. Cardona, Lixia Luo, Yan Ma, Christopher E. Nelson, Jacqueline N. Robinson-Hamm, Charles A. Gersbach, Rebecca D. Dodd, David G. Kirsch. Using CRISPR/Cas9 to generate primary soft tissue sarcoma in genetically engineered and wild-type mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2810. doi:10.1158/1538-7445.AM2017-2810

Induction of Mesenchymal-Epithelial Transitions in Sarcoma Cells

Phenotypic plasticity refers to a phenomenon in which cells transiently gain traits of another lineage. During carcinoma progression, phenotypic plasticity drives invasion, dissemination and metastasis. Indeed, while most of the studies of phenotypic plasticity have been in the context of epithelial-derived carcinomas, it turns out sarcomas, which are mesenchymal in origin, also exhibit phenotypic plasticity, with a subset of sarcomas undergoing a phenomenon that resembles a mesenchymal-epithelial transition (MET). Here, we developed a method comprising the miR-200 family and grainyhead-like 2 (GRHL2) to mimic this MET-like phenomenon observed in sarcoma patient samples.We sequentially express GRHL2 and the miR-200 family using cell transduction and transfection, respectively, to better understand the molecular underpinnings of these phenotypic transitions in sarcoma cells. Sarcoma cells expressing miR-200s and GRHL2 demonstrated enhanced epithelial characteristics in cell morphology and alteration of epithelial and mesenchymal biomarkers. Future studies using these methods can be used to better understand the phenotypic consequences of MET-like processes on sarcoma cells, such as migration, invasion, metastatic propensity, and therapy resistance.

Custom facial reconstruction for osteosarcoma of the jaw

Osteosarcoma accounts for most primary bone cancers in children and young adults. High-grade lesions are typically managed with a combination of chemotherapy and wide-margin surgical excision. Although this malignancy typically affects the metaphyseal region of long bones, it also can be seen in the axial skeleton. Of axial locations, tumors in the head and neck can be particularly troubling to treat. Segmental bone loss after resection of malignant mandibular tumors continues to present important challenges to the reconstructive surgeon. Recent advancements in 3-dimensional modeling have facilitated custom templates for patient-specific reconstructions. This report describes the case of a young woman with osteosarcoma of the mandible undergoing customized template composite facial reconstruction using a vascularized osteoseptocutaneous fibula flap.

Attitudes toward physician-assisted suicide among physicians in Vermont

BACKGROUND

Legislation on physician-assisted suicide (PAS) is being considered in a number of states since the passage of the Oregon Death With Dignity Act in 1994. Opinion assessment surveys have historically assessed particular subsets of physicians.

OBJECTIVE

To determine variables predictive of physicians' opinions on PAS in a rural state, Vermont, USA.

DESIGN

Cross-sectional mailing survey.

PARTICIPANTS

1052 (48% response rate) physicians licensed by the state of Vermont.

RESULTS

Of the respondents, 38.2% believed PAS should be legalised, 16.0% believed it should be prohibited and 26.0% believed it should not be legislated. 15.7% were undecided. Males were more likely than females to favour legalisation (42% vs 34%). Physicians who did not care for patients through the end of life were significantly more likely to favour legalisation of PAS than physicians who do care for patients with terminal illness (48% vs 33%). 30% of the respondents had experienced a request for assistance with suicide.

CONCLUSIONS

Vermont physicians' opinions on the legalisation of PAS is sharply polarised. Patient autonomy was a factor strongly associated with opinions in favour of legalisation, whereas the sanctity of the doctor-patient relationship was strongly associated with opinions in favour of not legislating PAS. Those in favour of making PAS illegal overwhelmingly cited moral and ethical beliefs as factors in their opinion. Although opinions on legalisation appear to be based on firmly held beliefs, approximately half of Vermont physicians who responded to the survey agree that there is a need for more education in palliative care and pain management.

Shuttle mission effects on glutamate receptor expression in the developing rodent spinal cord

BACKGROUND

Within the mammalian central nervous system (CNS), glutamate receptors play a fundamental role in excitatory neurotransmission and synaptic plasticity. Studies of the neonatal cerebral cortex suggests that rearing environment can influence the dynamic patterns of glutamate receptor subunit expression during development. We examined this issue in the developing spinal cord, a well studied region of the CNS in which activity-dependent synaptic plasticity is known to occur.

METHODS

We compared the abundance (by immunoblot analysis) and tissue distribution (by immunohistology) of glutamate receptor subunits in neonatal animals who participated in the Neurolab Space Shuttle mission. Flight animals were either postnatal day 8 or 13 at launch and spent the next 16 d in microgravity; tissues were recovered within 12 h of landing. Littermate control animals were reared on Earth at 1 G.

RESULT

Using semi-quantitative immunoblot assays, no statistically significant differences were found in the overall abundance of any glutamate receptor subunit in the spinal cords of the two groups of animals. Similarly, immunohistological examination of spinal cords revealed no evidence for differences in the distribution of glutamate receptor subunits between the two groups of animals.

CONCLUSIONS

These results indicate that the developmental regulation of glutamate receptor subunit expression in the spinal cord is not appreciably affected by the conditions associated with this space shuttle mission and prolonged rearing period in microgravity.