COL10A1 expression distinguishes a subset of cancer-associated fibroblasts present in the stroma of high-risk basal cell carcinoma.

BACKGROUND: Basal cell carcinoma (BCC) is the most frequently diagnosed skin cancer and the most common malignancy in humans. Different morphological subtypes of BCC are associated with low- or high-risk of recurrence and aggressiveness, but the underlying biology of how the individual subtypes arise remains largely unknown. Because the majority of BCCs appear to arise from mutations in the same pathway, we hypothesized that BCC development, growth and invasive potential is also influenced by the tumor microenvironment and in particular by cancer-associated fibroblasts (CAFs) and their secreted factors. OBJECTIVE: We aimed to characterize the stroma of the different BCC subtypes with a focus on CAF populations. METHODS: To investigate the stromal features of the different BCC subtypes, we applied laser-capture microdissection (LCM) followed by RNA sequencing. A cohort of 15 BCC samples from 5 different "pure" subtypes (superficial, nodular, micronodular, sclerosing and basosquamous; n=3 each) were selected and included in the analysis. Healthy skin was used as a control (n=6). We confirmed the results by immunohistochemistry. We validated our findings in two independent, public single-cell RNA sequencing (scRNAseq) datasets and by RNAscope. RESULTS: The stroma of the different BCC subtypes have distinct gene expression signatures. Nodular and micronodular seem to have the most similar signatures, while superficial and sclerosing the most different. By comparing low- and high-risk BCC subtypes, we observed that Collagen 10A1 (COL10A1) is overexpressed in the stroma of sclerosing/infiltrative and basosquamous but not micronodular high-risk subtypes. Those findings were confirmed by immunohistochemistry in a cohort of 89 different BCC and 13 healthy skin samples. Moreover, scRNAseq analysis of BCCs of two independent datasets showed that the COL10A1-expressing population of cells is associated with the stroma adjacent to invasive BCC and shows extracellular matrix remodeling features. CONCLUSION: We identified COL10A1 as a marker of high-risk BCC, in particular of the sclerosing/infiltrative and basosquamous subtypes. We demonstrated at the single cell level that COL10A1 is expressed by a specific CAF population associated with the stroma of invasive BCC. This opens up new tailored treatment options as well as a new prognostic biomarker for BCC progression.

Size-exclusion chromatography combined with DIA-MS enables deep proteome profiling of extracellular vesicles from melanoma plasma and serum.

Extracellular vesicles (EVs) are important players in melanoma progression, but their use as clinical biomarkers has been limited by the difficulty of profiling blood-derived EV proteins with high depth of coverage, the requirement for large input amounts, and complex protocols. Here, we provide a streamlined and reproducible experimental workflow to identify plasma- and serum- derived EV proteins of healthy donors and melanoma patients using minimal amounts of sample input. SEC-DIA-MS couples size-exclusion chromatography to EV concentration and deep-proteomic profiling using data-independent acquisition. From as little as 200 µL of plasma per patient in a cohort of three healthy donors and six melanoma patients, we identified and quantified 2896 EV-associated proteins, achieving a 3.5-fold increase in depth compared to previously published melanoma studies. To compare the EV-proteome to unenriched blood, we employed an automated workflow to deplete the 14 most abundant proteins from plasma and serum and thereby approximately doubled protein group identifications versus native blood. The EV proteome diverged from corresponding unenriched plasma and serum, and unlike the latter, separated healthy donor and melanoma patient samples. Furthermore, known melanoma markers, such as MCAM, TNC, and TGFBI, were upregulated in melanoma EVs but not in depleted melanoma plasma, highlighting the specific information contained in EVs. Overall, EVs were significantly enriched in intact membrane proteins and proteins related to SNARE protein interactions and T-cell biology. Taken together, we demonstrated the increased sensitivity of an EV-based proteomic workflow that can be easily applied to larger melanoma cohorts and other indications.

Isolation and detection of extracellular vesicles from melanoma cells and liquid biopsies using size-exclusion chromatography and nano-flow cytometry.

Characterization of extracellular vesicles (EVs) holds great promise for biomarker discovery and understanding of diseases, including melanoma, the deadliest skin cancer type. Here, we describe a size-exclusion chromatography method to isolate and concentrate EVs from patient material including (1) patient-derived melanoma cell line supernatants and (2) plasma and serum biopsies. Additionally, we provide a protocol to analyze EVs by nano-flow cytometry. EV suspensions obtained with the presented protocol can be used for several downstream analyses including RNA sequencing and proteomics.

The Role of Extracellular Vesicles in Melanoma Progression.

Cutaneous melanoma arises from a malignant transformation of the melanocytes in the skin. It is the deadliest form of skin cancer owing to its potential to metastasize. While recent advances in immuno-oncology have been successful in melanoma treatment, not all the patients respond to the treatment equally, thus individual pre-screening and personalized combination therapies are essential to stratify and monitor patients. Extracellular vesicles (EVs) have emerged as promising biomarker candidates to tackle these challenges. EVs are ~50-1000-nm-sized, lipid bilayer-enclosed spheres, which are secreted by almost all cell types, including cancer cells. Their cargo, such as nucleic acids, proteins, lipids, amino acids, and metabolites, can be transferred to target cells. Thanks to these properties, EVs can both provide a multiplexed molecular fingerprint of the cell of origin and thus serve as potential biomarkers, or reveal pathways important for cancer progression that can be targeted pharmaceutically. In this review we give a general overview of EVs and focus on their impact on melanoma progression. In particular, we shed light on the role of EVs in shaping the tumor-stroma interactions that facilitate metastasis and summarize the latest findings on molecular profiling of EV-derived miRNAs and proteins that can serve as potential biomarkers for melanoma progression.

Active Uptake and Trafficking of Nucleoside Triphosphates In Vivo.

Modified nucleoside triphosphates (NTPs) are powerful probes and medicines, but their anionic character impedes membrane permeability. As such, invasive delivery techniques, transport carriers, or prodrug strategies are required for their in vivo use. Here, we present a fluorescent 2'-deoxyribonucleoside triphosphate "TAMRA-dATP" that exhibits surprisingly high bioavailability in vivo. TAMRA-dATP spontaneously forms nanoparticles in Mg+2-containing buffers that are taken into the vesicles of living cells and animals by energy-dependent processes. In cell cultures, photochemical activation with yellow laser light (561 nm) facilitated endosomal escape of TAMRA-dATP, resulting in its metabolic incorporation into DNA in vitro. In contrast, in vivo studies revealed that TAMRA-dATP is extensively trafficked by active pathways into cellular DNA of zebrafish (Danio rerio) and Caenorhabditis elegans where DNA labeling was observed in live animals, even without photochemical release. Metabolic labeling of DNA in whole, living animals can therefore be achieved by simply soaking animals in a buffer containing TAMRA-dATP or a structurally related compound, Cy3-dATP.

A DNA replication-independent function of pre-replication complex genes during cell invasion in C. elegans.

Cell invasion is an initiating event during tumor cell metastasis and an essential process during development. A screen of C. elegans orthologs of genes overexpressed in invasive human melanoma cells has identified several components of the conserved DNA pre-replication complex (pre-RC) as positive regulators of anchor cell (AC) invasion. The pre-RC genes function cell-autonomously in the G1-arrested AC to promote invasion, independently of their role in licensing DNA replication origins in proliferating cells. While the helicase activity of the pre-RC is necessary for AC invasion, the downstream acting DNA replication initiation factors are not required. The pre-RC promotes the invasive fate by regulating the expression of extracellular matrix genes and components of the PI3K signaling pathway. Increasing PI3K pathway activity partially suppressed the AC invasion defects caused by pre-RC depletion, suggesting that the PI3K pathway is one critical pre-RC target. We propose that the pre-RC, or a part of it, acts in the postmitotic AC as a transcriptional regulator that facilitates the switch to an invasive phenotype.

Fluorescent dATP for DNA Synthesis In Vivo.

Fluorescent nucleoside triphosphates are powerful probes of DNA synthesis, but their potential use in living animals has been previously underexplored. Here, we report the synthesis and characterization of 7-deaza-(1,2,3-triazole)-2'-deoxyadenosine-5'-triphosphate (dATP) derivatives of tetramethyl rhodamine ("TAMRA-dATP"), cyanine ("Cy3-dATP"), and boron-dipyrromethene ("BODIPY-dATP"). Upon microinjection into live zebrafish embryos, all three compounds were incorporated into the DNA of dividing cells; however, their impact on embryonic toxicity was highly variable, depending on the exact structure of the dye. TAMRA-EdATP exhibited superior characteristics in terms of its high brightness, low toxicity, and rapid incorporation and depletion kinetics in both a vertebrate (zebrafish) and a nematode (Caenorhabditis elegans). TAMRA-EdATP allows for unprecedented, real-time visualization of DNA replication and chromosome segregation in vivo.

The role of cyclin D1 and Ki-67 in the development and prognostication of thin melanoma.

AIMS: Despite their low individual metastatic potential, thin melanomas (≤1 mm Breslow thickness) contribute significantly to melanoma mortality overall. Therefore, identification of prognostic biomarkers is particularly important in this subgroup of melanoma. Prompted by preclinical results, we investigated cyclin D1 protein and Ki-67 expression in in-situ, metastatic and non-metastatic thin melanomas. METHODS AND RESULTS: Immunohistochemistry was performed on 112 melanoma specimens, comprising 22 in situ, 48 non-metastatic and 42 metastatic thin melanomas. Overall, epidermal and dermal cyclin D1 and Ki-67 expression were semiquantitatively evaluated by three independent investigators and compared between groups. Epidermal Ki-67 expression did not differ statistically in in-situ and invasive melanoma (P = 0.7). Epidermal cyclin D1 expression was significantly higher in thin invasive than in in-situ melanoma (P = 0.003). No difference was found in cyclin D1 expression between metastatic and non-metastatic invasive tumours. Metastatic and non-metastatic thin melanomas did not show significant differences in epidermal expression of Ki-67 and cyclin D1 (P = 0.148 and P = 0.611, respectively). In contrast, strong dermal expression of Ki-67 was more frequent in metastatic than non-metastatic samples (28.6 versus 8.3%, respectively, P = 0.001). The prognostic value of dermal Ki-67 expression was confirmed by multivariate analysis (P = 0.047). CONCLUSION: We found an increased expression of cyclin D1 in invasive thin melanomas compared to in-situ melanomas, which supports a potential role of this protein in early invasion in melanoma, as suggested by preclinical findings. Moreover, our results confirm that high dermal Ki-67 expression is associated with an increased risk of development of metastasis in thin melanoma and could possibly serve as a prognostic biomarker in clinical practice, especially if combined with additional methods.

The Caenorhabditis elegans homolog of the Evi1 proto-oncogene, egl-43, coordinates G1 cell cycle arrest with pro-invasive gene expression during anchor cell invasion.

Cell invasion allows cells to migrate across compartment boundaries formed by basement membranes. Aberrant cell invasion is a first step during the formation of metastases by malignant cancer cells. Anchor cell (AC) invasion in C. elegans is an excellent in vivo model to study the regulation of cell invasion during development. Here, we have examined the function of egl-43, the homolog of the human Evi1 proto-oncogene (also called MECOM), in the invading AC. egl-43 plays a dual role in this process, firstly by imposing a G1 cell cycle arrest to prevent AC proliferation, and secondly, by activating pro-invasive gene expression. We have identified the AP-1 transcription factor fos-1 and the Notch homolog lin-12 as critical egl-43 targets. A positive feedback loop between fos-1 and egl-43 induces pro-invasive gene expression in the AC, while repression of lin-12 Notch expression by egl-43 ensures the G1 cell cycle arrest necessary for invasion. Reducing lin-12 levels in egl-43 depleted animals restored the G1 arrest, while hyperactivation of lin-12 signaling in the differentiated AC was sufficient to induce proliferation. Taken together, our data have identified egl-43 Evi1 as an important factor coordinating cell invasion with cell cycle arrest.

To Divide or Invade: A Look Behind the Scenes of the Proliferation-Invasion Interplay in the Caenorhabditis elegans Anchor Cell.

Cell invasion is defined by the capability of cells to migrate across compartment boundaries established by basement membranes (BMs). The development of complex organs involves regulated cell growth and regrouping of different cell types, which are enabled by controlled cell proliferation and cell invasion. Moreover, when a malignant tumor takes control over the body, cancer cells evolve to become invasive, allowing them to spread to distant sites and form metastases. At the core of the switch between proliferation and invasion are changes in cellular morphology driven by remodeling of the cytoskeleton. Proliferative cells utilize their actomyosin network to assemble a contractile ring during cytokinesis, while invasive cells form actin-rich protrusions, called invadopodia that allow them to breach the BMs. Studies of developmental cell invasion as well as of malignant tumors revealed that cell invasion and proliferation are two mutually exclusive states. In particular, anchor cell (AC) invasion during Caenorhabditis elegans larval development is an excellent model to study the transition from cell proliferation to cell invasion under physiological conditions. This mini-review discusses recent insights from the C. elegans AC invasion model into how G1 cell-cycle arrest is coordinated with the activation of the signaling networks required for BM breaching. Many regulators of the proliferation-invasion network are conserved between C. elegans and mammals. Therefore, the worm may provide important clues to better understand cell invasion and metastasis formation in humans.

Correction: Long-term C. elegans immobilization enables high resolution developmental studies in vivo.

Correction for 'Long-term C. elegans immobilization enables high resolution developmental studies in vivo' by Simon Berger et al., Lab Chip, 2018, 18, 1359-1368.

Long-term C. elegans immobilization enables high resolution developmental studies in vivo.

Live-imaging of C. elegans is essential for the study of conserved cellular pathways (e.g. EGFR/Wnt signaling) and morphogenesis in vivo. However, the usefulness of live imaging as a research tool has been severely limited by the need to immobilize worms prior to and during imaging. Conventionally, immobilization is achieved by employing both physical and chemical interventions. These are known to significantly affect many physiological processes, and thus limit our understanding of dynamic developmental processes. Herein we present a novel, easy-to-use microfluidic platform for the long-term immobilization of viable, normally developing C. elegans, compatible with image acquisition at high resolution, thereby overcoming the limitations associated with conventional worm immobilization. The capabilities of the platform are demonstrated through the continuous assessment of anchor cell (AC) invasion and distal tip cell (DTC) migration in larval C. elegans and germ cell apoptosis in adult C. elegans in vivo for the first time.

Cytokinesis: Closure resets your SIN.

A new study of fission yeast cell division has revealed a coupling between cytoplasmic partitioning and the turning-off of cytokinesis signalling that may be mediated by asymmetric protein distribution.

Restoration of lymphoid organ integrity through the interaction of lymphoid tissue-inducer cells with stroma of the T cell zone.

The generation of lymphoid microenvironments in early life depends on the interaction of lymphoid tissue-inducer cells with stromal lymphoid tissue-organizer cells. Whether this cellular interface stays operational in adult secondary lymphoid organs has remained elusive. We show here that during acute infection with lymphocytic choriomeningitis virus, antiviral cytotoxic T cells destroyed infected T cell zone stromal cells, which led to profound disruption of secondary lymphoid organ integrity. Furthermore, the ability of the host to respond to secondary antigens was lost. Restoration of the lymphoid microanatomy was dependent on the proliferative accumulation of lymphoid tissue-inducer cells in secondary lymphoid organs during the acute phase of infection and lymphotoxin alpha(1)beta(2) signaling. Thus, crosstalk between lymphoid tissue-inducer cells and stromal cells is reactivated in adults to maintain secondary lymphoid organ integrity and thereby contributes to the preservation of immunocompetence.

Dendritic cell-independent B cell activation during acute virus infection: a role for early CCR7-driven B-T helper cell collaboration.

This study provides a detailed spatiotemporal interaction analysis between B cells, Th cells, and dendritic cells (DC) during the generation of protective antiviral B cell immunity. Following vesicular stomatitis virus (VSV) infection, conditional ablation of CD11c-positive DC at the time-point of infection did not impair extrafollicular plasma cell generation and Ig class switching. In contrast, the generation of Th and B cell responses following immunization with recombinant VSV-glycoprotein was DC-dependent. Furthermore, we show that the CCR7-dependent interplay of the three cell-types is crucial for virus-neutralizing B cell responses in the presence of limiting amounts of Ag. An immediate event following VSV infection was the CCR7-mediated interaction of VSV-specific B and Th cells at the T cell-B cell zone border that facilitated plasma cell differentiation and Th cell activation. Taken together, these experiments provide evidence for a direct, CCR7-orchestrated and largely DC-independent mutual activation of Th cells and Ag-specific B cells that is most likely a critical step during early immune responses against cytopathic viruses.