Persistent Human KIT Receptor Signaling Disposes Murine Placenta to Premature Differentiation Resulting in Severely Disrupted Placental Structure and Functionality.

Activating mutations in the human KIT receptor is known to drive severe hematopoietic disorders and tumor formation spanning various entities. The most common mutation is the substitution of aspartic acid at position 816 to valine (D816V), rendering the receptor constitutively active independent of ligand binding. As the role of the KIT receptor in placental signaling cascades is poorly understood, we analyzed the impact of KITD816V expression on placental development using a humanized mouse model. Placentas from KITD816V animals present with a grossly changed morphology, displaying a reduction in labyrinth and spongiotrophoblast layer and an increase in the Parietal Trophoblast Giant Cell (P-TGC) layer. Elevated differentiation to P-TGCs was accompanied with reduced differentiation to other Trophoblast Giant Cell (TGC) subtypes and by severe decrease in proliferation. The embryos display growth retardation and die in utero. KITD816V-trophoblast stem cells (TSC) differentiate much faster compared to wild type (WT) controls. In undifferentiated KITD816V-TSCs, levels of Phosphorylated Extracellular-signal Regulated Kinase (P-ERK) and Phosphorylated Protein Kinase B (P-AKT) are comparable to wildtype cultures differentiating for 3-6 days. Accordingly, P-TGC markers Placental Lactogen 1 (PL1) and Proliferin (PLF) are upregulated as well. The results reveal that KIT signaling orchestrates the fine-tuned differentiation of the placenta, with special emphasis on P-TGC differentiation. Appropriate control of KIT receptor action is therefore essential for placental development and nourishment of the embryo.

Mass Spectrometry-Based Profiling of Histone Post-Translational Modifications in Uveal Melanoma Tissues, Human Melanocytes, and Uveal Melanoma Cell Lines - A Pilot Study.

Purpose: Epigenetic alterations in uveal melanoma (UM) are still neither well characterized, nor understood. In this pilot study, we sought to provide a deeper insight into the possible role of epigenetic alterations in the pathogenesis of UM and their potential prognostic relevance. To this aim, we comprehensively profiled histone post-translational modifications (PTMs), which represent epigenetic features regulating chromatin accessibility and gene transcription, in UM formalin-fixed paraffin-embedded (FFPE) tissues, control tissues, UM cell lines, and healthy melanocytes. Methods: FFPE tissues of UM (n = 24), normal choroid (n = 4), human UM cell lines (n = 7), skin melanocytes (n = 6), and uveal melanocytes (n = 2) were analyzed through a quantitative liquid chromatography-mass spectrometry (LC-MS) approach. Results: Hierarchical clustering showed a clear separation with several histone PTMs that changed significantly in a tumor compared to normal samples, in both tissues and cell lines. In addition, several acetylations and H4K20me1 showed lower levels in BAP1 mutant tumors. Some of these changes were also observed when we compared GNA11 mutant tumors with GNAQ tumors. The epigenetic profiling of cell lines revealed that the UM cell lines MP65 and UPMM1 have a histone PTM pattern closer to the primary tissues than the other cell lines analyzed. Conclusions: Our results suggest the existence of different histone PTM patterns that may be important for diagnosis and prognosis in UM. However, further analyses are needed to confirm these findings in a larger cohort. The epigenetic characterization of a panel of UM cell lines suggested which cellular models are more suitable for epigenetic investigations.

Inflammatory fibroid polyp of the renal pelvis: first report at an extra-gastrointestinal site with molecular confirmation.

Inflammatory fibroid polyps (IFP) are rare and benign mesenchymal tumours of the gastrointestinal tract. They are submucosal spindle cell lesions with an eosinophilic-rich inflammatory infiltrate and mutations in the platelet-derived growth factor receptor alpha (PDGFRA) gene. In this report, we present the case of a 74-year-old female with a solid tumour of the kidney, which presented as a bland proliferation of spindle cells with thin-walled blood vessels and an inflammatory infiltrate with eosinophilic granulocytes. Immunohistochemistry revealed a positivity for vimentin and a weak staining for CD99 and CD34 in the spindle cells. Because of the morphological similarity to IFPs of the gastrointestinal tract, a molecular pathology analysis was performed. This identified an oncogenic mutation in exon 18 of the PDGFRA gene, which is characteristic for inflammatory fibroid polyps of the gastrointestinal tract. To the best of our knowledge, this is the first case of an IFP in the urogenital tract.

TargetPlex FFPE-Direct DNA Library Preparation Kit for SiRe NGS panel: an international performance evaluation study.

AIM: Next generation sequencing (NGS) represents a key diagnostic tool to identify clinically relevant gene alterations for treatment-decision making in cancer care. However, the complex manual workflow required for NGS has limited its implementation in routine clinical practice. In this worldwide study, we validated the clinical performance of the TargetPlex FFPE-Direct DNA Library Preparation Kit for NGS analysis. Impressively, this new assay obviates the need for separate, labour intensive and time-consuming pre-analytical steps of DNA extraction, purification and isolation from formalin-fixed paraffin embedded (FFPE) specimens in the NGS workflow. METHODS: The TargetPlex FFPE-Direct DNA Library Preparation Kit, which enables NGS analysis directly from FFPE, was specifically developed for this study by TargetPlex Genomics Pleasanton, California. Eleven institutions agreed to take part in the study coordinated by the Molecular Cytopathology Meeting Group (University of Naples Federico II, Naples, Italy). All participating institutions received a specific Library Preparation Kit to test eight FFPE samples previously assessed with standard protocols. The analytical parameters and mutations detected in each sample were then compared with those previously obtained with standard protocols. RESULTS: Overall, 92.8% of the samples were successfully analysed with the TargetPlex FFPE-Direct DNA Library Preparation Kit on Thermo Fisher Scientific and Illumina platforms. Altogether, in comparison with the standard workflow, the TargetPlex FFPE-Direct DNA Library Preparation Kit was able to detect 90.5% of the variants. CONCLUSION: The TargetPlex FFPE-Direct DNA Library Preparation Kit combined with the SiRe panel constitutes a convenient, practical and robust cost-saving solution for FFPE NGS analysis in routine practice.

Cultivation of Clear Cell Renal Cell Carcinoma Patient-Derived Organoids in an Air-Liquid Interface System as a Tool for Studying Individualized Therapy.

Clear cell renal cell carcinoma (ccRCC) is the most common renal cancer accounting for 80% of all renal cancers as well as the majority of renal cancer-associated deaths. During the last decade, the treatment paradigm for ccRCC has radically changed. In particular, the recent development of immune checkpoint inhibitors (ICI) has led to an increased overall survival in the metastatic setting. Moreover, novel immune therapies targeting the tumor microenvironment have been developed. In this rapidly evolving treatment landscape, precise tools for personalized cancer therapy are needed. Here, we collected fresh tissue from 42 patients who underwent surgical resection for renal cell carcinoma. Part of the tissue was used to obtain formalin-fixed, paraffin-embedded samples or RNA. The remaining tissue was minced and cultured in a collagen-based three-dimensional, air-liquid interface (ALI) culture system. The generated patient-derived tumor organoids (ALI PDOs) were characterized by immunohistochemistry staining and RNA sequencing to validate their close similarity to the matched tumor. Immune cells and stromal cells within the microenvironment could be identified. Finally, we treated 10 ALI PDOs with the commonly used targeted cancer drug cabozantinib or the ICI nivolumab. Interestingly, we observed varying responses of ALI PDOs to these treatments and future studies are needed to investigate whether the ALI PDO approach could inform about treatment responses in patients. In conclusion, this three-dimensional ccRCC culture model represents a promising, facile tool for monitoring tumor responses to different types of therapies in a controlled manner, yet, still preserves the key features of the tumor of origin.

The spleen microenvironment influences disease transformation in a mouse model of KITD816V-dependent myeloproliferative neoplasm.

Activating mutations leading to ligand-independent signaling of the stem cell factor receptor KIT are associated with several hematopoietic malignancies. One of the most common alterations is the D816V mutation. In this study, we characterized mice, which conditionally express the humanized KITD816V receptor in the adult hematopoietic system to determine the pathological consequences of unrestrained KIT signaling during blood cell development. We found that KITD816V mutant animals acquired a myeloproliferative neoplasm similar to polycythemia vera, marked by a massive increase in red blood cells and severe splenomegaly caused by excessive extramedullary erythropoiesis. Moreover, we found mobilization of stem cells from bone marrow to the spleen. Splenectomy prior to KITD816V induction prevented expansion of red blood cells, but rapidly lead to a state of aplastic anemia and bone marrow fibrosis, reminiscent of post polycythemic myeloid metaplasia, the spent phase of polycythemia vera. Our results show that the extramedullary hematopoietic niche microenvironment significantly influences disease outcome in KITD816V mutant mice, turning this model a valuable tool for studying the interplay between functionally abnormal hematopoietic cells and their microenvironment during development of polycythemia vera-like disease and myelofibrosis.