Orthotopic model for the analysis of melanoma circulating tumor cells.

Metastatic melanoma, a highly lethal form of skin cancer, presents significant clinical challenges due to limited therapeutic options and high metastatic capacity. Recent studies have demonstrated that cancer dissemination can occur earlier, before the diagnosis of the primary tumor. The progress in understanding the kinetics of cancer dissemination is limited by the lack of animal models that accurately mimic disease progression. We have established a xenograft model of human melanoma that spontaneously metastasizes to lymph nodes and lungs. This model allows precise monitoring of melanoma progression and is suitable for the quantitative and qualitative analysis of circulating tumor cells (CTCs). We have validated a flow cytometry-based protocol for CTCs enumeration and isolation. We could demonstrate that (i) CTCs were detectable in the bloodstream from the fourth week after tumor initiation, coinciding with the lymph node metastases appearance, (ii) excision of the primary tumor accelerated the formation of metastases in lymph nodes and lungs as early as one-week post-surgery, accompanied by the increased numbers of CTCs, and (iii) CTCs change their surface protein signature. In summary, we present a model of human melanoma that can be effectively utilized for future drug efficacy studies.

Aryl hydrocarbon receptor as a drug target in advanced prostate cancer therapy - obstacles and perspectives.

Aryl hydrocarbon receptor (AhR) is a transcription factor that is primarily known as an intracellular sensor of environmental pollution. After five decades, the list of synthetic and toxic chemicals that activate AhR signaling has been extended to include a number of endogenous compounds produced by various types of cells via their metabolic activity. AhR signaling is active from the very beginning of embryonal development throughout the life cycle and participates in numerous biological processes such as control of cell proliferation and differentiation, metabolism of aromatic compounds of endogenous and exogenous origin, tissue regeneration and stratification, immune system development and polarization, control of stemness potential, and homeostasis maintenance. AhR signaling can be affected by various pharmaceuticals that may help modulate abnormal AhR signaling and drive pathological states. Given their role in immune system development and regulation, AhR antagonistic ligands are attractive candidates for immunotherapy of disease states such as advanced prostate cancer, where an aberrant immune microenvironment contributes to cancer progression and needs to be reeducated. Advanced stages of prostate cancer are therapeutically challenging and characterized by decreased overall survival (OS) due to the metastatic burden. Therefore, this review addresses the role of AhR signaling in the development and progression of prostate cancer and discusses the potential of AhR as a drug target for the treatment of advanced prostate cancer upon entering the phase of drug resistance and failure of first-line androgen deprivation therapy.Abbreviation: ADC: antibody-drug conjugate; ADT: androgen deprivation therapy; AhR: aryl hydrocarbon receptor; AR: androgen receptor; ARE: androgen response element; ARPI: androgen receptor pathway inhibitor; mCRPC: metastatic castration-resistant prostate cancer; DHT: 5a-dihydrotestosterone; FICZ: 6-formylindolo[3,2-b]carbazole; 3-MC: 3-methylcholanthrene; 6-MCDF: 6-methyl-1,3,8-trichlorodibenzofuran; MDSCs: myeloid-derived suppressor cells; PAHs: polycyclic aromatic hydrocarbons; PCa: prostate cancer; TAMs: tumor-associated macrophages; TF: transcription factor; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin; TME: tumor microenvironment; TRAMP: transgenic adenocarcinoma of the mouse prostate; TROP2: tumor associated calcium signal transducer 2.

Transcriptional and phenotypical alterations associated with a gradual benzo[a]pyrene-induced transition of human bronchial epithelial cells into mesenchymal-like cells.

The role of benzo[a]pyrene (BaP), a prominent genotoxic carcinogen and aryl hydrocarbon receptor (AhR) ligand, in tumor progression remains poorly characterized. We investigated the impact of BaP on the process of epithelial-mesenchymal transition (EMT) in normal human bronchial epithelial HBEC-12KT cells. Early morphological changes after 2-week exposure were accompanied with induction of SERPINB2, IL1, CDKN1A/p21 (linked with cell cycle delay) and chemokine CXCL5. After 8-week exposure, induction of cell migration and EMT-related pattern of markers/regulators led to induction of further pro-inflammatory cytokines or non-canonical Wnt pathway ligand WNT5A. This trend of up-regulation of pro-inflammatory genes and non-canonical Wnt pathway constituents was observed also in the BaP-transformed HBEC-12KT-B1 cells. In general, transcriptional effects of BaP differed from those of TGFß1, a prototypical EMT inducer, or a model non-genotoxic AhR ligand, TCDD. Carcinogenic polycyclic aromatic hydrocarbons could thus induce a unique set of molecular changes linked with EMT and cancer progression.

Expansions of tumor-reactive Vdelta1 gamma-delta T cells in newly diagnosed patients with chronic myeloid leukemia.

Recent studies have underscored the importance of gamma-delta (γδ) T cells in mediating potent MHC-unrestricted cytotoxicity in numerous malignancies. Here, we analyzed Vδ1 and Vδ2 γδ T cell subsets in newly diagnosed chronic myeloid leukemia (CML) patients (n = 40) who had initiated tyrosine kinase inhibitor (TKI) therapy including imatinib (n = 22), nilotinib (n = 14) and dasatinib (n = 4). Patient peripheral blood samples were analyzed at diagnosis and monitored prospectively at 3, 6, 12 and 18 months post-TKI. γδ T cells isolated from healthy donors and CML patients were used against K562, LAMA-84 and KYO-1 cell lines and against primary CML cells in cytotoxicity assays. We found large expansions of Vδ1 and Vδ2 T cells in patients at diagnosis compared to age-matched healthy donors (n = 40) (p < 0.0001). The γδ T cell reconstitution in patients on imatinib and also on nilotinib showed significant reductions of Vδ1 T cell and Vδ2 T cell absolute counts at 3 months compared to diagnosis. Importantly, Vδ1 and Vδ2 T absolute cell counts remained at normal levels from 3 months throughout the follow-up. Next, we observed susceptibility to specific lysis of primary CML tumor cells by Vδ1 T cells from healthy donors. Furthermore, we determined inherent cytotoxic reactivity by autologous patients' Vδ1 T lymphocytes against primary CML tumor cells. Finally, the TCR clonality profiles showed in CML patients mostly polyclonal repertoires regardless of the TKI. Our results provide further evidence into γδ T cell antileukemia immunity in CML that might be beneficial for long-term disease control and treatment outcome.

Inhibition of Aryl Hydrocarbon Receptor (AhR) Expression Disrupts Cell Proliferation and Alters Energy Metabolism and Fatty Acid Synthesis in Colon Cancer Cells.

The aryl hydrocarbon receptor (AhR) plays a wide range of physiological roles in cellular processes such as proliferation, migration or control of immune responses. Several studies have also indicated that AhR might contribute to the regulation of energy balance or cellular metabolism. We observed that the AhR is upregulated in tumor epithelial cells derived from colon cancer patients. Using wild-type and the corresponding AhR knockout (AhR KO) variants of human colon cancer cell lines HCT116 and HT-29, we analyzed possible role(s) of the AhR in cell proliferation and metabolism, with a focus on regulation of the synthesis of fatty acids (FAs). We observed a decreased proliferation rate in the AhR KO cells, which was accompanied with altered cell cycle progression, as well as a decreased ATP production. We also found reduced mRNA levels of key enzymes of the FA biosynthetic pathway in AhR KO colon cancer cells, in particular of stearoyl-CoA desaturase 1 (SCD1). The loss of AhR was also associated with reduced expression and/or activity of components of the PI3K/Akt pathway, which controls lipid metabolism, and other lipogenic transcriptional regulators, such as sterol regulatory element binding transcription factor 1 (SREBP1). Together, our data indicate that disruption of AhR activity in colon tumor cells may, likely in a cell-specific manner, limit their proliferation, which could be linked with a suppressive effect on their endogenous FA metabolism. More attention should be paid to potential mechanistic links between overexpressed AhR and colon tumor cell metabolism.

Toll-Like Receptor 3 Overexpression Induces Invasion of Prostate Cancer Cells, whereas Its Activation Triggers Apoptosis.

Toll-like receptor 3 (TLR3) is an endosomal receptor expressed in several immune and epithelial cells. Recent studies have highlighted its expression also in solid tumors, including prostate cancer (PCa), and have described its role primarily in the proinflammatory response and induction of apoptosis. It is up-regulated in some castration-resistant prostate cancers. However, the role of TLR3 in prostate cancer progression remains largely unknown. The current study experimentally demonstrated that exogenous TLR3 activation in PCa cell lines leads to a significant induction of secretion of the cytokines IL-6, IL-8, and interferon-ß, depending on the model and chemoresistance status. Transcriptomic analysis of TLR3-overexpressing cells revealed a functional program that is enriched for genes involved in the regulation of cell motility, migration, and tumor invasiveness. Increased motility, migration, and invasion in TLR3-overexpressing cell line were confirmed by several in vitro assays and using an orthotopic prostate xenograft model in vivo. Furthermore, TLR3-ligand induced apoptosis via cleavage of caspase-3/7 and poly (ADP-ribose) polymerase, predominantly in TLR3-overexpressing cells. These results indicate that TLR3 may be involved in prostate cancer progression and metastasis; however, it might also represent an Achilles heel of PCa, which can be exploited for targeted therapy.

Regulation of Neuroendocrine-like Differentiation in Prostate Cancer by Non-Coding RNAs.

Neuroendocrine prostate cancer (NEPC) represents a variant of prostate cancer that occurs in response to treatment resistance or, to a much lesser extent, de novo. Unravelling the molecular mechanisms behind transdifferentiation of cancer cells to neuroendocrine-like cancer cells is essential for development of new treatment opportunities. This review focuses on summarizing the role of small molecules, predominantly microRNAs, in this phenomenon. A published literature search was performed to identify microRNAs, which are reported and experimentally validated to modulate neuroendocrine markers and/or regulators and to affect the complex neuroendocrine phenotype. Next, available patients' expression datasets were surveyed to identify deregulated microRNAs, and their effect on NEPC and prostate cancer progression is summarized. Finally, possibilities of miRNA detection and quantification in body fluids of prostate cancer patients and their possible use as liquid biopsy in prostate cancer monitoring are discussed. All the addressed clinical and experimental contexts point to an association of NEPC with upregulation of miR-375 and downregulation of miR-34a and miR-19b-3p. Together, this review provides an overview of different roles of non-coding RNAs in the emergence of neuroendocrine prostate cancer.

Polychlorinated environmental toxicants affect sphingolipid metabolism during neurogenesis in vitro.

Sphingolipids (SLs) are important signaling molecules and functional components of cellular membranes. Although SLs are known as crucial regulators of neural cell physiology and differentiation, modulations of SLs by environmental neurotoxicants in neural cells and their neuronal progeny have not yet been explored. In this study, we used in vitro models of differentiated neuron-like cells, which were repeatedly exposed during differentiation to model environmental toxicants, and we analyzed changes in sphingolipidome, cellular morphology and gene expression related to SL metabolism or neuronal differentiation. We compared these data with the results obtained in undifferentiated neural cells with progenitor-like features. As model polychlorinated organic pollutants, we used 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3,3'-dichlorobiphenyl (PCB11) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153). PCB153 revealed itself as the most prominent deregulator of SL metabolism and as potent toxicant during early phases of in vitro neurogenesis. TCDD exerted only minor changes in the levels of analysed lipid species, however, it significantly changed the rate of pro-neuronal differentiation and deregulated expression of neuronal markers during neurogenesis. PCB11 acted as a potent disruptor of in vitro neurogenesis, which induced significant alterations in SL metabolism and cellular morphology in both differentiated neuron-like models (differentiated NE4C and NG108-15 cells). We identified ceramide-1-phosphate, lactosylceramides and several glycosphingolipids to be the most sensitive SL species to exposure to polychlorinated pollutants. Additionally, we identified deregulation of several genes related to SL metabolism, which may be explored in future as potential markers of developmental neurotoxicity.

Changes in Sphingolipid Profile of Benzo[a]pyrene-Transformed Human Bronchial Epithelial Cells Are Reflected in the Altered Composition of Sphingolipids in Their Exosomes.

Sphingolipids (SLs), glycosphingolipids (GSLs), and eicosanoids are bioactive lipids, which play important roles in the etiology of various diseases, including cancer. However, their content and roles in cancer cells, and in particular in the exosomes derived from tumor cells, remain insufficiently characterized. In this study, we evaluated alterations of SL and GSL levels in transformed cells and their exosomes, using comparative HPLC-MS/MS analysis of parental human bronchial epithelial cells HBEC-12KT and their derivative, benzo[a]pyrene-transformed HBEC-12KT-B1 cells with the acquired mesenchymal phenotype. We examined in parallel SL/GSL contents in the exosomes released from both cell lines. We found significant alterations of the SL/GSL profile in the transformed cell line, which corresponded well with alterations of the SL/GSL profile in exosomes derived from these cells. This suggested that a majority of SLs and GSLs were transported by exosomes in the same relative pattern as in the cells of origin. The only exceptions included decreased contents of sphingosin, sphingosin-1-phosphate, and lactosylceramide in exosomes derived from the transformed cells, as compared with the exosomes derived from the parental cell line. Importantly, we found increased levels of ceramide phosphate, globoside Gb3, and ganglioside GD3 in the exosomes derived from the transformed cells. These positive modulators of epithelial-mesenchymal transition and other pro-carcinogenic processes might thus also contribute to cancer progression in recipient cells. In addition, the transformed HBEC-12KT-B1 cells also produced increased amounts of eicosanoids, in particular prostaglandin E2. Taken together, the exosomes derived from the transformed cells with specifically upregulated SL and GSL species, and increased levels of eicosanoids, might contribute to changes within the cancer microenvironment and in recipient cells, which could in turn participate in cancer development. Future studies should address specific roles of individual SL and GSL species identified in the present study.

Complex Alterations of Fatty Acid Metabolism and Phospholipidome Uncovered in Isolated Colon Cancer Epithelial Cells.

The development of colon cancer, one of the most common malignancies, is accompanied with numerous lipid alterations. However, analyses of whole tumor samples may not always provide an accurate description of specific changes occurring directly in tumor epithelial cells. Here, we analyzed in detail the phospholipid (PL), lysophospholipid (lysoPL), and fatty acid (FA) profiles of purified EpCAM+ cells, isolated from tumor and adjacent non-tumor tissues of colon cancer patients. We found that a number of FAs increased significantly in isolated tumor cells, which also included a number of long polyunsaturated FAs. Higher levels of FAs were associated with increased expression of FA synthesis genes, as well as with altered expression of enzymes involved in FA elongation and desaturation, including particularly fatty acid synthase, stearoyl-CoA desaturase, fatty acid desaturase 2 and ELOVL5 fatty acid elongase 5 We identified significant changes in ratios of specific lysoPLs and corresponding PLs. A number of lysophosphatidylcholine and lysophosphatidylethanolamine species, containing long-chain and very-long chain FAs, often with high numbers of double bonds, were significantly upregulated in tumor cells. Increased de novo synthesis of very long-chain FAs, or, altered uptake or incorporation of these FAs into specific lysoPLs in tumor cells, may thus contribute to reprogramming of cellular phospholipidome and membrane alterations observed in colon cancer.

Dasatinib treatment long-term results among imatinib-resistant/intolerant patients with chronic phase chronic myeloid leukemia are favorable in daily clinical practice.

To evaluate long-term real-life results of dasatinib therapy among chronic phase chronic myeloid leukemia patients resistant or intolerant to imatinib, we retrospectively analyzed data of 118 patients treated in centers participating in the database INFINITY. With median follow-up of 37 months, estimated 5-year cumulative incidences of complete cytogenetic and major molecular responses were 78% and 68%, respectively. The estimated 5-year probability of overall survival (OS) and event-free survival (EFS) were 86% and 83%, respectively. Both OS and EFS were significantly improved among patients with BCR-ABL1 transcript level ≤10% at 3 months. Dasatinib toxicity was tolerable however persistent in almost half our patients, even after years of therapy. Pleural effusion occurred in 29% of patients and was responsible for 30% of dasatinib discontinuations. Our results confirmed very good efficacy and acceptable toxicity of dasatinib in second line setting and support the evidence and importance of high-quality real-life CML patient management.

A prolonged exposure of human lung carcinoma epithelial cells to benzo[a]pyrene induces p21-dependent epithelial-to-mesenchymal transition (EMT)-like phenotype.

Deciphering the role of the aryl hydrocarbon receptor (AhR) in lung cancer cells may help us to better understand the role of toxic AhR ligands in lung carcinogenesis, including cancer progression. We employed human lung carcinoma A549 cells to investigate their fate after continuous two-week exposure to model AhR agonists, genotoxic benzo[a]pyrene (BaP; 1 µM) and non-genotoxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 nM). While TCDD increased proliferative rate of A549 cells, exposure to BaP decreased cell proliferation and induced epithelial-to-mesenchymal transition (EMT)-like phenotype, which was associated with enhanced cell migration, invasion, and altered cell morphology. Although TCDD also suppressed expression of E-cadherin and activated some genes linked to EMT, it did not induce the EMT-like phenotype. The results of transcriptomic analysis, and the opposite effects of BaP and TCDD on cell proliferation, indicated that a delay in cell cycle progression, together with a slight increase of senescence (when coupled with AhR activation), favors the induction of EMT-like phenotype. The shift towards EMT-like phenotype observed after simultaneous treatment with TCDD and mitomycin C (an inhibitor of cell proliferation) confirmed the hypothesis. Since BaP decreased cell proliferative rate via induction of p21 expression, we generated the A549 cell model with reduced p21 expression and exposed it to BaP for two weeks. The p21 knockdown suppressed the BaP-mediated EMT-like phenotype in A549 cells, thus confirming that a delayed cell cycle progression, together with p21-dependent induction of senescence-related chemokine CCL2, may contribute to induction of EMT-like cell phenotype in lung cells exposed to genotoxic AhR ligands.

Hypoxia/Hif1α prevents premature neuronal differentiation of neural stem cells through the activation of Hes1.

Embryonic neural stem cells (NSCs), comprising neuroepithelial and radial glial cells, are indispensable precursors of neurons and glia in the mammalian developing brain. Since the process of neurogenesis occurs in a hypoxic environment, the question arises of how NSCs deal with low oxygen tension and whether it affects their stemness. Genes from the hypoxia-inducible factors (HIF) family are well known factors governing cellular response to hypoxic conditions. In this study, we have discovered that the endogenous stabilization of hypoxia-inducible factor 1α (Hif1α) during neural induction is critical for the normal development of the NSCs pool by preventing its premature depletion and differentiation. The knock-out of the Hif1α gene in mESC-derived neurospheres led to a decrease in self-renewal of NSCs, paralleled by an increase in neuronal differentiation. Similarly, neuroepithelial cells differentiated in hypoxia exhibited accelerated neurogenesis soon after Hif1α knock-down. In both models, the loss of Hif1α was accompanied by an immediate drop in neural repressor Hes1 levels while changes in Notch signaling were not observed. We found that active Hif1α/Arnt1 transcription complex bound to the evolutionarily conserved site in Hes1 gene promoter in both neuroepithelial cells and neural tissue of E8.5 - 9.5 embryos. Taken together, these results emphasize the novel role of Hif1α in the regulation of early NSCs population through the activation of neural repressor Hes1, independently of Notch signaling.

Gadolinium labelled nanoliposomes as the platform for MRI theranostics: in vitro safety study in liver cells and macrophages.

Gadolinium (Gd)-based contrast agents are extensively used for magnetic resonance imaging (MRI). Liposomes are potential nanocarrier-based biocompatible platforms for development of new generations of MRI diagnostics. Liposomes with Gd-complexes (Gd-lip) co-encapsulated with thrombolytic agents can serve both for imaging and treatment of various pathological states including stroke. In this study, we evaluated nanosafety of Gd-lip containing PE-DTPA chelating Gd+3 prepared by lipid film hydration method. We detected no cytotoxicity of Gd-lip in human liver cells including cancer HepG2, progenitor (non-differentiated) HepaRG, and differentiated HepaRG cells. Furthermore, no potential side effects of Gd-lip were found using a complex system including general biomarkers of toxicity, such as induction of early response genes, oxidative, heat shock and endoplasmic reticulum stress, DNA damage responses, induction of xenobiotic metabolizing enzymes, and changes in sphingolipid metabolism in differentiated HepaRG. Moreover, Gd-lip did not show pro-inflammatory effects, as assessed in an assay based on activation of inflammasome NLRP3 in a model of human macrophages, and release of eicosanoids from HepaRG cells. In conclusion, this in vitro study indicates potential in vivo safety of Gd-lip with respect to hepatotoxicity and immunopathology caused by inflammation.

Colon Cancer and Perturbations of the Sphingolipid Metabolism.

The development and progression of colorectal cancer (CRC), a major cause of cancer-related death in the western world, is accompanied with alterations of sphingolipid (SL) composition in colon tumors. A number of enzymes involved in the SL metabolism have been found to be deregulated in human colon tumors, in experimental rodent studies, and in human colon cancer cells in vitro. Therefore, the enzymatic pathways that modulate SL levels have received a significant attention, due to their possible contribution to CRC development, or as potential therapeutic targets. Many of these enzymes are associated with an increased sphingosine-1-phosphate/ceramide ratio, which is in turn linked with increased colon cancer cell survival, proliferation and cancer progression. Nevertheless, more attention should also be paid to the more complex SLs, including specific glycosphingolipids, such as lactosylceramides, which can be also deregulated during CRC development. In this review, we focus on the potential roles of individual SLs/SL metabolism enzymes in colon cancer, as well as on the pros and cons of employing the current in vitro models of colon cancer cells for lipidomic studies investigating the SL metabolism in CRC.

Screening of Cellular Stress Responses Induced by Ambient Aerosol Ultrafine Particle Fraction PM0.5 in A549 Cells.

Effects of airborne particles on the expression status of markers of cellular toxic stress and on the release of eicosanoids, linked with inflammation and oxidative damage, remain poorly characterized. Therefore, we proposed a set of various methodological approaches in order to address complexity of PM0.5-induced toxicity. For this purpose, we used a well-characterized model of A549 pulmonary epithelial cells exposed to a non-cytotoxic concentration of ambient aerosol particle fraction PM0.5 for 24 h. Electron microscopy confirmed accumulation of PM0.5 within A549 cells, yet, autophagy was not induced. Expression profiles of various cellular stress response genes that have been previously shown to be involved in early stress responses, namely unfolded protein response, DNA damage response, and in aryl hydrocarbon receptor (AhR) and p53 signaling, were analyzed. This analysis revealed induction of GREM1, EGR1, CYP1A1, CDK1A, PUMA, NOXA and GDF15 and suppression of SOX9 in response to PM0.5 exposure. Analysis of eicosanoids showed no oxidative damage and only a weak anti-inflammatory response. In conclusion, this study helps to identify novel gene markers, GREM1, EGR1, GDF15 and SOX9, that may represent a valuable tool for routine testing of PM0.5-induced in vitro toxicity in lung epithelial cells.