Investigating the mechanisms of peritoneal metastasis in gastric adenocarcinoma using a novel ex vivo peritoneal explant model.

Gastric adenocarcinoma, commonly known as stomach cancer, has a predilection for metastasis to the peritoneum, which portends limited survival. The peritoneal metastatic cascade remains poorly understood, and existing models fail to recapitulate key elements of the interaction between cancer cells and the peritoneal layer. To explore the underlying cellular and molecular mechanisms of peritoneal metastasis, we developed an ex vivo human peritoneal explant model. Fresh peritoneal tissue samples were suspended, mesothelial layer down but without direct contact, above a monolayer of red-fluorescent dye stained AGS human gastric adenocarcinoma cells for 24 h, then washed thoroughly. Implantation of AGS cells within the explanted peritoneum and invasion beyond the mesothelial layer were examined serially using real-time confocal fluorescence microscopy. Histoarchitecture of the explanted peritoneum was preserved over 5 days ex vivo. Both implantation and invasion were suppressed by restoration of functional E-cadherin through stable transfection of AGS cells, demonstrating sensitivity of the model to molecular manipulation. Thus, our ex vivo human peritoneal explant model permits meaningful investigation of the pathways and mechanism that contribute to peritoneal metastasis. The model will facilitate screening of new therapies that target peritoneal dissemination of gastric, ovarian and colorectal cancer.

Impact of the coronavirus disease 2019 pandemic on delivery of and models for supportive and palliative care for oncology patients.

PURPOSE OF REVIEW: Supportive and palliative care services have been an important component of the overall COVID-19 pandemic response. However, significant changes in the provision and models of care were needed in order to optimize the care delivered to vulnerable cancer patients. This review discusses the evolution of palliative and supportive care service in response to the pandemic, and highlights remaining challenges. RECENT FINDINGS: Direct competition for resources, as well as widespread implementation of safety measures resulted in major shifts in the mode of assessment and communication with cancer patients by supportive care teams. Telemedicine/virtual consultation and follow-up visits became an integral strategy, with high uptake and satisfaction amongst patients, families and providers. However, inequities in access to the required technologies were sometimes exposed. Hospice/palliative care unit (PCU) bed occupancy declined markedly because of restrictive visitation policies. Collection of patient-reported outcome (PRO) data was suspended in many cancer centers, with resulting under-recognition of anxiety and depression in ambulatory patients. As in many other areas, disparities in delivery of supportive and palliative care were magnified by the pandemic. SUMMARY: Virtual care platforms have been widely adopted and will continue to be used to include a wider circle of family/friends and care providers in the provision of palliative and supportive care. To facilitate equitable delivery of supportive care within a pandemic, further research and resources are needed to train and support generalists and palliative care providers. Strategies to successfully collect PROs from all patients in a virtual manner must be developed and implemented.

Challenges in virtual collection of patient-reported data: a prospective cohort study conducted in COVID-19 era.

Prior to the COVID-19 pandemic, patients attending ambulatory clinics at cancer centers in Ontario completed the Edmonton Symptom Assessment Scale (ESAS) at each visit. At our center, completion was via touchpad, with assistance from clinic volunteers. As of March 2020, clinic appointments were conducted virtually when possible and touch pads removed. We anticipated a negative impact on the collection of patient-reported outcomes (PROs) and the recognition of severe symptoms. METHODS: We performed a prospective cross-sectional cohort study to investigate remote ESAS completion by patients with appointments at a weekly surgical oncology clinic. Patients in the initial study cohort were asked to complete and return the ESAS virtually (V). Given low completion rates, the ensuing cohort was asked to complete a hard-copy (HC) ESAS. For the final cohort, we provided remote, personal mentorship by a member of the care team to support virtual electronic ESAS completion (virtual-mentored (VM) cohort). RESULTS: Between May and July 2020, a total of 174 patient encounters were included in the study. For the V cohort, 20/46 patients (44%) successfully completed and returned the electronic ESAS, compared to 49/50 (98%) for the HC cohort. For the VM cohort, the overall completion rate was 74% (58/78); however, 12 of these 58 patients did not independently complete a virtual ESAS. Virtual questionnaire completion was not predicted by age, sex, or tumor site, although patients who completed the ESAS were more likely to be in active management rather than surveillance (p = 0.04). Of all completed forms, 42% revealed a depression score of ≥2, and 27% an anxiety score of ≥4. CONCLUSIONS: We identified significant barriers to the virtual completion of ESAS forms, with a lack of predictive variables. The severe degree of psychological distress reported by ~50% of respondents demonstrates the need for ongoing regular collection/review of these data. Innovative solutions are required to overcome barriers to the virtual collection of PROs.

Toward Better Understanding and Management of Solitary Fibrous Tumor.

Solitary fibrous tumor (SFT) comprises a histologic spectrum of soft tissue neoplasms that are characterized by the unique NAB2-STAT6 gene fusion. Changes in diagnostic terminology and site-specific classification over the past few decades have resulted in a disjointed literature. Complete surgical excision with preservation of function remains the mainstay of treatment. New risk stratification systems including risk factors such as mitotic rate, age, tumor size, and presence of necrosis, among others, can be used to predict risk of recurrence or metastasis. Long-term follow-up after surgical resection is recommended. The clinical manifestations, diagnosis, management, and prognosis of SFT are reviewed here.

FAM46C/TENT5C functions as a tumor suppressor through inhibition of Plk4 activity.

Polo like kinase 4 (Plk4) is a tightly regulated serine threonine kinase that governs centriole duplication. Increased Plk4 expression, which is a feature of many common human cancers, causes centriole overduplication, mitotic irregularities, and chromosomal instability. Plk4 can also promote cancer invasion and metastasis through regulation of the actin cytoskeleton. Herein we demonstrate physical interaction of Plk4 with FAM46C/TENT5C, a conserved protein of unknown function until recently. FAM46C localizes to centrioles, inhibits Plk4 kinase activity, and suppresses Plk4-induced centriole duplication. Interference with Plk4 function by FAM46C was independent of the latter's nucleotidyl transferase activity. In addition, FAM46C restrained cancer cell invasion and suppressed MDA MB-435 cancer growth in a xenograft model, opposing the effect of Plk4. We demonstrate loss of FAM46C in patient-derived colorectal cancer tumor tissue that becomes more profound with advanced clinical stage. These results implicate FAM46C as a tumor suppressor that acts by inhibiting Plk4 activity.

Plk4 Promotes Cancer Invasion and Metastasis through Arp2/3 Complex Regulation of the Actin Cytoskeleton.

The polo family serine threonine kinase Plk4 has been proposed as a therapeutic target in advanced cancers based on increased expression in primary human cancers, facilitation of tumor growth in murine xenograft models, and centrosomal amplification induced by its overexpression. However, both the causal link between these phenomena and the feasibility of selective Plk4 inhibition remain unclear. Here we characterize Plk4-dependent cancer cell migration and invasion as well as local invasion and metastasis of cancer xenografts. Plk4 depletion suppressed cancer invasion and induced an epithelial phenotype in poorly differentiated breast cancer cells. In an unbiased BioID screen for Plk4 interactors, we identified members of the Arp2/3 complex and confirmed a physical and functional interaction between Plk4 and Arp2 in mediating Plk4-driven cancer cell movement. This interaction is mediated through the Plk4 Polo-box 1-Polo-box 2 domain and results in phosphorylation of Arp2 at the T237/T238 activation site, which is required for Plk4-driven cell movement. Our results validate Plk4 as a therapeutic target in cancer patients and reveal a new role for Plk4 in regulating Arp2/3-mediated actin cytoskeletal rearrangement. Cancer Res; 77(2); 434-47. ©2016 AACR.

Peptide surface modification of methacrylamide chitosan for neural tissue engineering applications.

Nerve fibres are guided to their targets by the combined actions of chemotactic and haptotactic stimuli; however, translating these stimuli to a scaffold that will promote nerve regeneration is nontrivial. In pursuit of this goal, we synthesized and characterized cell-adhesive, biodegradable chitosan scaffolds. Chitosan amine groups were reacted with methacrylic anhydride resulting in a water soluble methacrylamide chitosan (MC) that was then crosslinked by radical polymerization resulting in a scaffold. Biodegradability by lysozyme and penetrability of the scaffold by rat superior cervical ganglion (SCG) neurons were studied. Maleimide-terminated cell adhesive peptides, mi-GDPGYIGSR and mi-GQASSIKVAV, were coupled to a thiolated form of MC to promote cell adhesion. The MC scaffold was found to be porous, biodegradable, and to allow neurite penetration. Interestingly, all of these properties were found to depend upon the amount of initiator used in crosslinking. Covalent modification of the MC scaffold with cell adhesive peptides significantly improved neuronal adhesion and neurite outgrowth. The MC can be crosslinked to form a novel scaffold, where our results demonstrate its suitability in neural tissue engineering and its potential for other engineered tissues, such as cartilage repair, where chitosan has already demonstrated some utility.

Controlling cell adhesion and degradation of chitosan films by N-acetylation.

As part of our ongoing effort to develop a biodegradable nerve guidance channel based on chitin/chitosan, we conducted a systematic in vitro study on the biodegradation and neural cell compatibility of chitosan and N-acetylated chitosan. The in vitro degradation (pH 7.4, 37 degrees C) in the presence of 1.5 microg/ml lysozyme showed a progressive mass loss to greater than 50% within 4 weeks for films with 30-70% acetylation. In contrast, the degradation of samples with very low or high acetylation was minimal over the 4-week period. Neural cell compatibility of chitosan and N-acetylated chitosan was tested using primary chick dorsal root ganglion (DRG) neurons. All chitosan-based films showed DRG cell adhesion after 2 days of culture. However, cell viability decreased with increasing acetylation. Chitosan that was 0.5% acetylated had the greatest cell viability, which was approximately 8 times higher than that of chitosan that was 11% acetylated. Chitosan with 0.5% and 11% acetylation showed more and longer neurites than the other samples studied. Thus chitosan amine content can be tuned for optimal biodegradation and cell compatibility, which are important for tissue engineering in the nervous system.