Development and optimization of orthotopic liver metastasis xenograft mouse models in uveal melanoma

A rat-based preclinical platform facilitating transcatheter hepatic arterial infusion in immunodeficient rats with liver xenografts of patient-derived pancreatic ductal adenocarcinoma

Liver metastases from pancreatic ductal adenocarcinoma (PDAC) are highly fatal. A rat-based patient-derived tumor xenograft (PDX) model is available for transcatheter therapy. This study aimed to create an immunodeficient rat model with liver xenografts of patient-derived primary PDAC and evaluate efficacy of hepatic arterial infusion chemotherapy with cisplatin in this model. Three patient-derived PDACs were transplanted into the livers of 21 rats each (totally, 63 rats), randomly assigned into hepatic arterial infusion, systemic venous infusion, and control groups (n = 7 each) four weeks post-implantation. Computed tomography evaluated tumor volumes before and four weeks after treatment. Post-euthanasia, resected tumor specimens underwent histopathological examination. A liver-implanted PDAC PDX rat model was established in all 63 rats, with first CT identifying all tumors. Four weeks post-treatment, arterial infusion groups exhibited significantly smaller tumor volumes than controls for all three tumors on second CT. Xenograft tumors histologically maintained adenocarcinoma features compared to original patient tumors. Ki67 expression was significantly lower in arterial infusion groups than in the other two for the three tumors, indicating reduced tumor growth in PDX rats. A liver-implanted PDAC PDX rat model was established as a rat-based preclinical platform. Arterial cisplatin infusion chemotherapy represents a potential therapy for PDAC liver metastasis.

Lineage commitment pathways epigenetically oppose oncogenic Gαq/11-YAP signaling in dormant disseminated uveal melanoma

The mechanisms driving late relapse in uveal melanoma (UM) patients remains a medical mystery and major challenge. Clinically it is inferred that UM disseminated cancer cells (DCCs) persist asymptomatic for years-to-decades mainly in the liver before they manifest as symptomatic metastasis. Here we reveal using Gαq/11 mut /BAP wt human uveal melanoma models and human UM metastatic samples, that the neural crest lineage commitment nuclear receptor NR2F1 is a key regulator of spontaneous UM DCC dormancy in the liver. Using a quiescence reporter, RNA-seq and multiplex imaging we revealed that rare dormant UM DCCs upregulate NR2F1 expression and genes related to neural crest programs while repressing gene related to cell cycle progression. Gain and loss of function assays showed that NR2F1 silences YAP1/TEAD1 transcription downstream of Gαq/11 signaling and that NR2F1 expression can also be repressed by YAP1. YAP1 expression is repressed by NR2F1 binding to its promoter and changing the histone H3 tail activation marks to repress YAP1 transcription. In vivo CRISPR KO of NR2F1 led dormant UM DCCs to awaken and initiate relentless liver metastatic growth. Cut&Run and bulk RNA sequencing further confirmed that NR2F1 epigenetically stimulates neuron axon guidance and neural lineage programs, and it globally represses gene expression linked to G-protein signaling to drive dormancy. Pharmacological inhibition of Gαq/11 mut signaling resulted in NR2F1 upregulation and robust UM growth arrest, which was also achieved using a novel NR2F1 agonist. Our work sheds light on the molecular underpinnings of UM dormancy revealing that transcriptional programs driven by NR2F1 epigenetically short-circuit Gαq/11 signaling to its downstream target YAP1.

Highlights

Quiescent solitary uveal melanoma (UM) DCCs in the liver up- and down-regulate neural crest and cell cycle progression programs, respectively.NR2F1 drives solitary UM DCC dormancy by antagonizing the Gαq/11-YAP1 pathway; small molecule Gαq/11 inhibition restores NR2F1 expression and quiescence. NR2F1 short-circuits oncogenic YAP1 and G-protein signaling via a chromatin remodeling program. Loss of function of NR2F1 in dormant UM DCCs leads to aggressive liver metastasis.

Graphical abstract

INPP5A phosphatase is a synthetic lethal target in GNAQ and GNA11-mutant melanomas

Activating mutations in GNAQ/GNA11 occur in over 90% of uveal melanomas (UMs), the most lethal melanoma subtype; however, targeting these oncogenes has proven challenging and inhibiting their downstream effectors show limited clinical efficacy. Here, we performed genome-scale CRISPR screens along with computational analyses of cancer dependency and gene expression datasets to identify the inositol-metabolizing phosphatase INPP5A as a selective dependency in GNAQ/11-mutant UM cells in vitro and in vivo. Mutant cells intrinsically produce high levels of the second messenger inositol 1,4,5 trisphosphate (IP3) that accumulate upon suppression of INPP5A, resulting in hyperactivation of IP3-receptor signaling, increased cytosolic calcium and p53-dependent apoptosis. Finally, we show that GNAQ/11-mutant UM cells and patients' tumors exhibit elevated levels of IP4, a biomarker of enhanced IP3 production; these high levels are abolished by GNAQ/11 inhibition and correlate with sensitivity to INPP5A depletion. Our findings uncover INPP5A as a synthetic lethal vulnerability and a potential therapeutic target for GNAQ/11-mutant-driven cancers.

Imipridones inhibit tumor growth and improve survival in an orthotopic liver metastasis mouse model of human uveal melanoma

Purpose

Uveal melanoma (UM) is a highly aggressive disease with very few treatment options. We previously demonstrated that mUM is characterized by high oxidative phosphorylation (OXPHOS). Here we tested the anti-tumor, signaling and metabolic effects of imipridones, CLPP activators which reduce OXPHOS indirectly and have demonstrated safety in patients.

Experimental Design

We assessed CLPP expression in UM patient samples. We tested the effects of imipridones (ONC201, ONC212) on the growth, survival, signaling and metabolism of UM cell lines in vitro, and for therapeutic effects in vivo in UM liver metastasis models.

Results

CLPP expression was confirmed in primary and mUM patient samples. ONC201/212 treatment of UM cell lines in vitro decreased OXPHOS effectors, inhibited cell growth and migration, and induced apoptosis. ONC212 increased metabolic stress and apoptotic pathways, inhibited amino acid metabolism, and induced cell death-related lipids. ONC212 also decreased tumor burden and increased survival in vivo in two UM liver metastasis models.

Conclusion

Imipridones are a promising strategy for further testing and development in mUM.

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.

Deep learning classification of uveal melanoma based on histopathological images and identification of a novel indicator for prognosis of patients

BACKGROUND

Deep learning has been extensively used in digital histopathology. The purpose of this study was to test deep learning (DL) algorithms for predicting the vital status of whole-slide image (WSI) of uveal melanoma (UM).

METHODS

We developed a deep learning model (Google-net) to predict the vital status of UM patients from histopathological images in TCGA-UVM cohort and validated it in an internal cohort. The histopathological DL features extracted from the model and then were applied to classify UM patients into two subtypes. The differences between two subtypes in clinical outcomes, tumor mutation, and microenvironment, and probability of drug therapeutic response were investigated further.

RESULTS

We observed that the developed DL model can achieve a high accuracy of >  = 90% for patches and WSIs prediction. Using 14 histopathological DL features, we successfully classified UM patients into Cluster1 and Cluster2 subtypes. Compared to Cluster2, patients in the Cluster1 subtype have a poor survival outcome, increased expression levels of immune-checkpoint genes, higher immune-infiltration of CD8 + T cell and CD4 + T cells, and more sensitivity to anti-PD-1 therapy. Besides, we established and verified prognostic histopathological DL-signature and gene-signature which outperformed the traditional clinical features. Finally, a well-performed nomogram combining the DL-signature and gene-signature was constructed to predict the mortality of UM patients.

CONCLUSIONS

Our findings suggest that DL model can accurately predict vital status in UM patents just using histopathological images. We found out two subgroups based on histopathological DL features, which may in favor of immunotherapy and chemotherapy. Finally, a well-performing nomogram that combines DL-signature and gene-signature was constructed to give a more straightforward and reliable prognosis for UM patients in treatment and management.

scRNA-Seq and imaging mass cytometry analyses unveil iNKT cells-mediated anti-tumor immunity in pancreatic cancer liver metastasis

Invariant natural killer T (iNKT) cells are innate-like T cells that are abundant in liver sinusoids and play a critical role in tumor immunity. However, the role of iNKT cells in pancreatic cancer liver metastasis (PCLM) has not been fully explored. In this study, we employed a hemi-spleen pancreatic tumor cell injection mouse model of PCLM, a model that closely mimics clinical conditions in humans, to explore the role of iNKT cells in PCLM. Activation of iNKT cells with α-galactosylceramide (αGC) markedly increased immune cell infiltration and suppressed PCLM progression. Via single cell RNA sequencing (scRNA-seq) we profiled over 30,000 immune cells from normal liver and PCLM with or without αGC treatment and were able to characterize the global changes of the immune cells in the tumor microenvironment upon αGC treatment, identifying a total of 12 subpopulations. Upon treatment with αGC, scRNA-Seq and flow cytometry analyses revealed increased cytotoxic activity of iNKT/NK cells and skewing CD4 T cells towards a cytotoxic Th1 profile and CD8 T cells towards a cytotoxic profile, characterized by higher proliferation and reduced exhaustion marker PD1 expression. Moreover, αGC treatment excluded tumor associated macrophages. Lastly, imaging mass cytometry analysis uncovered the reduced epithelial to mesenchymal transition related markers and increased active CD4 and CD8 T cells in PCLM with αGC treatment. Overall, our findings uncover the protective function of activated iNKT cells in pancreatic cancer liver metastasis through increased NK and T cell immunity and decreased tumor associated macrophages.

Orthotopic murine xenograft model of uveal melanoma with spontaneous liver metastasis

Uveal melanoma is the most common intraocular malignancy in adults. Despite the effective primary treatment, up to 50% of patients with uveal melanoma will develop metastatic lesions mainly in the liver, which are resistant to conventional chemotherapy and lead to patient's death. To date, no orthotopic murine models of uveal melanoma which can develop spontaneous metastasis are available for preclinical studies. Here, we describe a spontaneous metastatic model of uveal melanoma based on the orthotopic injection of human uveal melanoma cells into the suprachoroidal space of immunodeficient NSG mice. All mice injected with bioluminescent OMM2.5 ( n  = 23) or MP41 ( n  = 19) cells developed a primary tumor. After eye enucleation, additional bioluminescence signals were detected in the lungs and in the liver. At necropsy, histopathological studies confirmed the presence of lung metastases in 100% of the mice. Liver metastases were assessed in 87 and in 100% of the mice that received OMM2.5 or MP41 cells, respectively. All tumors and metastatic lesions expressed melanoma markers and the signaling molecules insulin-like growth factor type I receptor and myristoylated alanine-rich C-kinase substrate, commonly activated in uveal melanoma. The novelty of this orthotopic mouse xenograft model is the development of spontaneous metastases in the liver from the primary site, reproducing the organoespecificity of metastasis observed in uveal melanoma patients. The faster growth and the high metastatic incidence may be attributed at least in part, to the severe immunodeficiency of NSG mice. This model may be useful for preclinical testing of targeted therapies with potential uveal melanoma antimetastatic activity and to study the mechanisms involved in liver metastasis.

Safety and Feasibility of Contrast-Enhanced Computed Tomography with a Nanoparticle Contrast Agent for Evaluation of Diethylnitrosamine-Induced Liver Tumors in a Rat Model

RATIONALE AND OBJECTIVES

Safety and feasibility of contrast-enhanced computed tomography (CECT) with a nanoparticulate contrast agent, ExiTron nano 12000, was evaluated in a rat liver tumor model.

MATERIALS AND METHODS

This study employed eighteen 8-week-old male F344 rats. Six rats given tap water for 8 weeks further divided into two: Control group and Normal Liver with CECT group. Six rats each were given tap water containing diethylnitrosamine (DEN) at 100 ppm for 8 or 14 weeks; Adenoma group and Hepatocellular carcinoma (HCC) group, respectively. Biochemical marker values and adverse events were evaluated after CT imaging. ExiTron nano 12000 was evaluated for the hepatic contrast enhancement, and the detection and measurement of liver nodules by CECT after 8- and 14-weeks administration of DEN. Post-mortem liver specimens were evaluated by hematoxylin-eosin (HE) staining, and the number and size of liver nodules were measured. The HCC group was evaluated for diagnostic concordance between HE-stained and CECT-detected nodules.

RESULTS

The contrast agent enhanced liver and was tolerated after CECT in 15 rats. Biochemical parameter values did not differ significantly between the Control and Normal Liver groups. The numbers of CECT-detected nodules in the Adenoma and HCC groups were 14.8 ± 5.1, and 32.4 ± 8.1, respectively. The HCC group had 3.6 ± 2.7 of pathological HCCs, which were identified by CECT. The size of CECT-detected HCCs correlated significantly with that of pathological HCCs (r = 0.966, p < 0.0001).

CONCLUSION

CECT with ExiTron nano 12000 is a safe and feasible method to measure tumors in a rat liver tumor model.

Ultrasound Guided Surgery as a Refinement Tool in Oncology Research

Refinement is one of the ethical pillars of the use of animals in research. Ultrasonography is currently used in human medicine as a surgical tool for guided biopsies and this idea can be applied to preclinical research thanks to the development of specific instruments. This will eliminate the necessity of a surgical opening for implanting cells in specific organs or taking samples from tissues. The approach for the injection will depend on the target but most of the case is going to be lateral, with the probe in a ventral position and the needle going into from the lateral. This is the situation for the thyroid gland, heart, liver, spleen, kidney, pancreas, uterus, and testicles. Other approaches, such as the dorsal, can be used in the spleen or kidney. The maximum injected volume will depend on the size of the structure. For biopsies, the technical protocol is similar to the injection knowing that in big organs such as the liver, spleen, or kidney we can take several samples moving slightly the needle inside the structure. In all cases, animals must be anesthetized and minimum pain management is required after the intervention.

The long non-coding RNA SAMMSON is essential for uveal melanoma cell survival

Long non-coding RNAs (lncRNAs) can exhibit cell-type and cancer-type specific expression profiles, making them highly attractive as therapeutic targets. Pan-cancer RNA sequencing data revealed broad expression of the SAMMSON lncRNA in uveal melanoma (UM), the most common primary intraocular malignancy in adults. Currently, there are no effective treatments for UM patients with metastatic disease, resulting in a median survival time of 6-12 months. We aimed to investigate the therapeutic potential of SAMMSON inhibition in UM. Antisense oligonucleotide (ASO)-mediated SAMMSON inhibition impaired the growth and viability of a genetically diverse panel of uveal melanoma cell lines. These effects were accompanied by an induction of apoptosis and were recapitulated in two uveal melanoma patient derived xenograft (PDX) models through subcutaneous ASO delivery. SAMMSON pulldown revealed several candidate interaction partners, including various proteins involved in mitochondrial translation. Consequently, inhibition of SAMMSON impaired global, mitochondrial and cytosolic protein translation levels and mitochondrial function in uveal melanoma cells. The present study demonstrates that SAMMSON expression is essential for uveal melanoma cell survival. ASO-mediated silencing of SAMMSON may provide an effective treatment strategy to treat primary and metastatic uveal melanoma patients.

Orthotopic Human Metastatic Uveal Melanoma Xenograft Mouse Models: Applications for Understanding the Pathophysiology and Therapeutic Management of Metastatic Uveal Melanoma

The propensity of uveal melanoma to metastasize to the liver hinders the accrual of micro-metastatic and end-stage disease tissue samples and restricts the investigation of metastatic uveal melanoma (MUM). Pre-clinical experimental animal models of MUM can help elucidate the pathophysiology of metastatic lesions and provide a tool for designing new therapeutic approaches for MUM. Here, we present an advanced model of hepatic metastases that enables quantitatively visualizing the development of individual hepatic tumor clones and estimating their growth kinetics and colonization efficiency. Similar to clinically observed liver metastases, these models enable the assessment of growth kinetics of the liver micro-metastases and the testing of therapeutic approaches for the treatment of MUM. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Experimental patient-derived xenograft mouse model of metastatic uveal melanoma Basic Protocol 2: Experimental liver micro-metastatic mouse model using splenic injection of metastatic uveal melanoma cells.

Modeling pancreatic cancer in mice for experimental therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy that is characterized by early metastasis, low resectability, high recurrence, and therapy resistance. The experimental mouse models have played a central role in understanding the pathobiology of PDAC and in the preclinical evaluation of various therapeutic modalities. Different mouse models with targetable pathological hallmarks have been developed and employed to address the unique challenges associated with PDAC progression, metastasis, and stromal heterogeneity. Over the years, mouse models have evolved from simple cell line-based heterotopic and orthotopic xenografts in immunocompromised mice to more complex and realistic genetically engineered mouse models (GEMMs) involving multi-gene manipulations. The GEMMs, mostly driven by KRAS mutation(s), have been widely accepted for therapeutic optimization due to their high penetrance and ability to recapitulate the histological, molecular, and pathological hallmarks of human PDAC, including comparable precursor lesions, extensive metastasis, desmoplasia, perineural invasion, and immunosuppressive tumor microenvironment. Advanced GEMMs modified to express fluorescent proteins have allowed cell lineage tracing to provide novel insights and a new understanding about the origin and contribution of various cell types in PDAC pathobiology. The syngeneic mouse models, GEMMs, and target-specific transgenic mice have been extensively used to evaluate immunotherapies and study therapy-induced immune modulation in PDAC yielding meaningful results to guide various clinical trials. The emerging mouse models for parabiosis, hepatic metastasis, cachexia, and image-guided implantation, are increasingly appreciated for their high translational significance. In this article, we describe the contribution of various experimental mouse models to the current understanding of PDAC pathobiology and their utility in evaluating and optimizing therapeutic modalities for this lethal malignancy.

Tumor-Associated Macrophages-Implications for Molecular Oncology and Imaging

Tumor-associated macrophages (TAMs) represent the largest group of leukocytes within the tumor microenvironment (TME) of solid tumors and orchestrate the composition of anti- as well as pro-tumorigenic factors. This makes TAMs an excellent target for novel cancer therapies. The plasticity of TAMs resulting in varying membrane receptors and expression of intracellular proteins allow the specific characterization of different subsets of TAMs. Those markers similarly allow tracking of TAMs by different means of molecular imaging. This review aims to provides an overview of the origin of tumor-associated macrophages, their polarization in different subtypes, and how characteristic markers of the subtypes can be used as targets for molecular imaging and theranostic approaches.