Zebrafish Patient-Derived Xenograft Model as a Preclinical Platform for Uveal Melanoma Drug Discovery

The effects of perfluorooctanoic acid on breast cancer metastasis depend on the phenotypes of the cancer cells: An in vivo study with zebrafish xenograft model

Per- and polyfluorinated substances (PFAS) have been associated with numerous human diseases. Recent in vitro studies have implicated the association of PFAS with an increased risk of breast cancer in humans. This study aimed to assess the toxic effects of PFAS during the development of human breast cancer using a zebrafish xenograft model. Perfluorooctanoic acid (PFOA) was used as a PFAS chemical of interest for this study. Two common breast cancer cell lines, MCF-7 and MDA-MB-231, were used to represent the diversity of breast cancer phenotypes. Human preadipocytes were co-implanted with the breast cancer cells into the zebrafish embryos to optimize the microenvironment for tumor cells in vivo. With this modified model, we evaluated the potential effects of the PFOA on the metastatic potential of the two types of breast cancer cells. The presence of human preadipocytes resulted in an enhancement to the metastasis progress of the two types of cells, including the promotion of cell in vivo migration and proliferation, and the increased expression levels of metastatic biomarkers. The enhancement of MCF-7 proliferation by preadipocytes was observed after 2 days post injection (dpi) while the increase of MDA-MB-231 proliferation was seen after 6 dpi. The breast cancer metastatic biomarkers, cadherin 1 (cdh1), and small breast epithelial mucin (sbem) genes demonstrated significant down- and upregulations respectively, by the co-injection of preadipocytes. In the optimized xenograft model, the PFOA consistently promoted cell proliferation and migration and altered the metastatic biomarker expression in MCF-7, which suggested a metastatic effect of PFOA on MCF-7. However, those effects were not consistently observed in MDA-MB-231. The presence of the preadipocytes in the xenograft model may provide a necessary microenvironment for the progress of tumor cells in zebrafish embryos. The finding suggested that the impacts of PFOA exposure on different phenotypes of breast cancers may differ.

Novel Uveal Melanoma Patient-Derived Organoid Models Recapitulate Human Disease to Support Translational Research

Purpose

A lack of representative human disease models has limited the translation of new and more effective treatments in uveal melanoma (UM), the most common primary adult intraocular malignancy. To fill this critical need, we developed and characterized a multicenter biobank of UM patient-derived organoids (PDOs).

Methods

UM patients requiring enucleation from 2019 to 2024 donated tumor tissue for PDO generation. PDOs were cultured in Cultrex and compared to donor primary tumor using exome sequencing, RNA sequencing, and immunohistochemistry. The ability of PDOs to maintain the transformed phenotype was evaluated in an orthotopic xenograft model and monitored with fundus imaging. ATAC sequencing and drug response assays were done in a subset of PDOs to explore the feasibility of their use for mechanistic and translational studies.

Results

PDOs were successfully established in 40 of 44 cases (91%), retained clinically relevant mutations and molecular markers from the primary tumor, and displayed similar gene expression profiles and well-validated clinical prognostic markers of the disease. PDOs retained tumorigenic capacity in an in vivo model resembling human disease progression. Finally, we demonstrated that PDOs were a feasible platform to identify and evaluate novel therapeutic targets and investigate differential, personalized drug response.

Conclusions

PDO models offer a new platform with improved representation of human UM to aid in translational research for this dismal condition.

Uveal Melanoma Zebrafish Xenograft Models Illustrate the Mutation Status-Dependent Effect of Compound Synergism or Antagonism

Purpose

Uveal melanoma (UM) is the most common primary intraocular malignancy with a high probability of metastatic disease. Although excellent treatment options for primary UM are available, therapy for metastatic disease remain limited. Drug discovery studies using mouse models have thus far failed to provide therapeutic solutions, highlighting the need for novel models. Here, we optimize zebrafish xenografts as a potential model for drug discovery by showcasing the behavior of multiple cell lines and novel findings on mutation-dependent compound synergism/antagonism using Z-Tada; an algorithm to objectively characterize output measurements.

Methods

Prognostic relevant primary (N = 4) and metastatic UM (N = 1) cell lines or healthy melanocytes (N = 2) were inoculated at three distinct inoculation sites. Standardized quantifications independent of inoculation site were obtained using Z-Tada; an algorithm to measure tumor burden and the number, size, and distance of disseminated tumor cells. Sequentially, we utilized this model to validate combinatorial synergism or antagonism seen in vitro.

Results

Detailed analysis of 691 zebrafish xenografts demonstrated perivitelline space inoculation provided robust data with high probability of cell dissemination. Cell lines with more invasive behavior (SF3B1mut and BAP1mut) behaved most aggressive in this model. Combinatorial drug treatment illustrated synergism or antagonism is mutation-dependent, which were confirmed in vivo. Combinatorial treatment differed per xenograft-model, as it either inhibited overall tumor burden or cell dissemination.

Conclusions

Perivitelline space inoculation provides robust zebrafish xenografts with the ability for high-throughput drug screening and robust data acquisition using Z-Tada. This model demonstrates that drug discovery for uveal melanoma must take mutational subclasses into account, especially in combinatorial treatment discoveries.

Zebrafish live imaging: a strong weapon in anticancer drug discovery and development

Developing anticancer drugs is a complex and time-consuming process. The inability of current laboratory models to reflect important aspects of the tumor in vivo limits anticancer medication research. Zebrafish is a rapid, semi-automated in vivo screening platform that enables the use of non-invasive imaging methods to monitor morphology, survival, developmental status, response to drugs, locomotion, or other behaviors. Zebrafish models are widely used in drug discovery and development for anticancer drugs, especially in conjunction with live imaging techniques. Herein, we concentrated on the use of zebrafish live imaging in anticancer therapeutic research, including drug screening, efficacy assessment, toxicity assessment, and mechanism studies. Zebrafish live imaging techniques have been used in numerous studies, but this is the first time that these techniques have been comprehensively summarized and compared side by side. Finally, we discuss the hypothesis of Zebrafish Composite Model, which may provide future directions for zebrafish imaging in the field of cancer research.

A Simple, Rapid, and Effective Method for Tumor Xenotransplantation Analysis in Transparent Zebrafish Embryos

In vivo studies of tumor behavior are a staple of cancer research; however, the use of mice presents significant challenges in cost and time. Here, we present larval zebrafish as a transplant model that has numerous advantages over murine models, including ease of handling, low expense, and short experimental duration. Moreover, the absence of an adaptive immune system during larval stages obviates the need to generate and use immunodeficient strains. While established protocols for xenotransplantation in zebrafish embryos exist, we present here an improved method involving embryo staging for faster transfer, survival analysis, and the use of flow cytometry to assess disease burden. Embryos are staged to facilitate rapid cell injection into the yolk of the larvae and cell marking to monitor the consistency of the injected cell bolus. After injection, embryo survival analysis is assessed up to 7 days post injection (dpi). Finally, disease burden is also assessed by marking transferred cells with a fluorescent protein and analysis by flow cytometry. Flow cytometry is enabled by a standardized method of preparing cell suspensions from zebrafish embryos, which could also be used in establishing the primary culture of zebrafish cells. In summary, the procedure described here allows a more rapid assessment of the behavior of tumor cells in vivo with larger numbers of animals per study arm and in a more cost-effective manner.

Recent Advances in Molecular and Genetic Research on Uveal Melanoma

Uveal melanoma (UM), a distinct subtype of melanoma, presents unique challenges in its clinical management due to its complex molecular landscape and tendency for liver metastasis. This review highlights recent advancements in understanding the molecular pathogenesis, genetic alterations, and immune microenvironment of UM, with a focus on pivotal genes, such as GNAQ/11, BAP1, and CYSLTR2, and delves into the distinctive genetic and chromosomal classifications of UM, emphasizing the role of mutations and chromosomal rearrangements in disease progression and metastatic risk. Novel diagnostic biomarkers, including circulating tumor cells, DNA and extracellular vesicles, are discussed, offering potential non-invasive approaches for early detection and monitoring. It also explores emerging prognostic markers and their implications for patient stratification and personalized treatment strategies. Therapeutic approaches, including histone deacetylase inhibitors, MAPK pathway inhibitors, and emerging trends and concepts like CAR T-cell therapy, are evaluated for their efficacy in UM treatment. This review identifies challenges in UM research, such as the limited treatment options for metastatic UM and the need for improved prognostic tools, and suggests future directions, including the discovery of novel therapeutic targets, immunotherapeutic strategies, and advanced drug delivery systems. The review concludes by emphasizing the importance of continued research and innovation in addressing the unique challenges of UM to improve patient outcomes and develop more effective treatment strategies.

Uveal melanoma modeling in mice and zebrafish

Despite extensive research and refined therapeutic options, the survival for metastasized uveal melanoma (UM) patients has not improved significantly. UM, a malignant tumor originating from melanocytes in the uveal tract, can be asymptomatic and small tumors may be detected only during routine ophthalmic exams; making early detection and treatment difficult. UM is the result of a number of characteristic somatic alterations which are associated with prognosis. Although UM morphology and biology have been extensively studied, there are significant gaps in our understanding of the early stages of UM tumor evolution and effective treatment to prevent metastatic disease remain elusive. A better understanding of the mechanisms that enable UM cells to thrive and successfully metastasize is crucial to improve treatment efficacy and survival rates. For more than forty years, animal models have been used to investigate the biology of UM. This has led to a number of essential mechanisms and pathways involved in UM aetiology. These models have also been used to evaluate the effectiveness of various drugs and treatment protocols. Here, we provide an overview of the molecular mechanisms and pharmacological studies using mouse and zebrafish UM models. Finally, we highlight promising therapeutics and discuss future considerations using UM models such as optimal inoculation sites, use of BAP1mut-cell lines and the rise of zebrafish models.

Resistance to immune checkpoint therapies by tumour-induced T-cell desertification and exclusion: key mechanisms, prognostication and new therapeutic opportunities

Immune checkpoint therapies (ICT) can reinvigorate the effector functions of anti-tumour T cells, improving cancer patient outcomes. Anti-tumour T cells are initially formed during their first contact (priming) with tumour antigens by antigen-presenting cells (APCs). Unfortunately, many patients are refractory to ICT because their tumours are considered to be 'cold' tumours-i.e., they do not allow the generation of T cells (so-called 'desert' tumours) or the infiltration of existing anti-tumour T cells (T-cell-excluded tumours). Desert tumours disturb antigen processing and priming of T cells by targeting APCs with suppressive tumour factors derived from their genetic instabilities. In contrast, T-cell-excluded tumours are characterised by blocking effective anti-tumour T lymphocytes infiltrating cancer masses by obstacles, such as fibrosis and tumour-cell-induced immunosuppression. This review delves into critical mechanisms by which cancer cells induce T-cell 'desertification' and 'exclusion' in ICT refractory tumours. Filling the gaps in our knowledge regarding these pro-tumoral mechanisms will aid researchers in developing novel class immunotherapies that aim at restoring T-cell generation with more efficient priming by APCs and leukocyte tumour trafficking. Such developments are expected to unleash the clinical benefit of ICT in refractory patients.