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MicroRNAs (miRNAs) are crucial post-transcriptional regulators of gene expression, and their deregulation contributes to many aspects of cancer development and progression. Thus, miRNAs provide insight into oncogenic mechanisms and represent promising targets for new therapeutic approaches. A type of cancer that is still in urgent need of improved treatment options is triple negative breast cancer (TNBC). Therefore, we aimed to characterize a novel miRNA with a potential role in TNBC. Based on a previous study, we selected miR-4646-5p, a miRNA with a still unknown function in breast cancer. We discovered that higher expression of miR-4646-5p in TNBC patients is associated with better survival. In vitro assays showed that miR-4646-5p overexpression reduces growth, proliferation, and migration of TNBC cell lines, whereas inhibition had the opposite effect. Furthermore, we found that miR-4646-5p inhibits the tube formation ability of endothelial cells, which may indicate anti-angiogenic properties. By whole transcriptome analysis, we not only observed that miR-4646-5p downregulates many oncogenic factors, like tumor-promoting cytokines and migration- and invasion-related genes, but were also able to identify a direct target, the GRAM domain-containing protein 1B (GRAMD1B). GRAMD1B is involved in cellular cholesterol transport and its knockdown phenocopied the growth-reducing effects of miR-4646-5p. We thus conclude that GRAMD1B may partly contribute to the diverse tumor-suppressive effects of miR-4646-5p in TNBC.

Background: Triple negative breast cancer (TNBC) is a particularly aggressive and difficult-to-treat subtype of breast cancer that requires the development of novel therapeutic strategies. To pave the way for such developments it is essential to characterize new molecular players in TNBC. MicroRNAs (miRNAs) constitute interesting candidates in this regard as they are frequently deregulated in cancer and contribute to numerous aspects of carcinogenesis., Methods and Results: Here, we discovered that miR-4649-5p, a miRNA yet uncharacterized in breast cancer, is associated with better overall survival of TNBC patients. Ectopic upregulation of the otherwise very low endogenous expression levels of miR-4646-5p significantly decreased the growth, proliferation, and migration of TNBC cells. By performing whole transcriptome analysis and physical interaction assays, we were able to identify the phosphatidylinositol phosphate kinase PIP5K1C as a direct target of miR-4649-5p. Downregulation or pharmacologic inhibition of PIP5K1C phenocopied the growth-reducing effects of miR-4649-5p. PIP5K1C is known to play an important role in migration and cell adhesion, and we could furthermore confirm its impact on downstream PI3K/AKT signaling. Combinations of miR-4649-5p upregulation and PIP5K1C or AKT inhibition, using the pharmacologic inhibitors UNC3230 and capivasertib, respectively, showed additive growth-reducing effects in TNBC cells., Conclusion: In summary, miR-4649-5p exerts broad tumor-suppressive effects in TNBC and shows potential for combined therapeutic approaches targeting the PIP5K1C/PI3K/AKT signaling axis., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Background: The presence of autoantibodies in the serum of cancer patients has been associated with immune-checkpoint inhibitor (ICI) therapy response and immune-related adverse events (irAEs). A prospective evaluation of different autoantibodies in different cancer entities is missing., Materials and Methods: In this prospective cohort study, we included a pan-cancer cohort of patients undergoing ICI treatment and measured a comprehensive panel of autoantibodies at treatment start and at the time point of first response evaluation. The presence and induction of autoantibodies (ANA, ENA, myositis, hepatopathy, rheumatoid arthritis) in different cancer entities were assessed and the association between autoantibodies and disease control rate (DCR), objective response rate (ORR), and progression-free survival (PFS), as well as the development of grade 3 or higher irAEs were evaluated by logistic regression models, cox proportional hazard models, and Kaplan-Meier estimators., Results: Of 44 patients with various cancer entities, neither the presence of any positive autoantibody measurement nor the presence of positive antinuclear antibodies (ANA) [≥1:80] at baseline was associated with the examined clinical endpoints (DCR, ORR, PFS) in univariable and multivariable analyses. After 8-12 weeks of ICI treatment, DCR, ORR, and PFS did not significantly differ between patients with and without any positive autoantibody measurement or positive ANA titers. The frequency of irAEs did not differ depending on autoantibody status of the patients., Conclusion: Autoantibodies at treatment initiation or induction after 8-12 weeks of ICI treatment are not associated with treatment efficacy as indicated by DCR, ORR, and PFS or higher grade irAEs., (© 2022 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

The RNA-binding protein ALYREF (THOC4) is involved in transcriptional regulation and nuclear mRNA export, though its role and molecular mode of action in breast carcinogenesis are completely unknown. Here, we identified high ALYREF expression as a factor for poor survival in breast cancer patients. ALYREF significantly influenced cellular growth, apoptosis and mitochondrial energy metabolism in breast cancer cells as well as breast tumorigenesis in orthotopic mouse models. Transcriptional profiling, phenocopy and rescue experiments identified the short isoform of the lncRNA NEAT1 as a molecular trigger for ALYREF effects in breast cancer. Mechanistically, we found that ALYREF binds to the NEAT1 promoter region to enhance the global NEAT1 transcriptional activity. Importantly, by stabilizing CPSF6, a protein that selectively activates the post-transcriptional generation of the short isoform of NEAT1, as well as by direct binding and stabilization of the short isoform of NEAT1, ALYREF selectively fine-tunes the expression of the short NEAT1 isoform. Overall, our study describes ALYREF as a novel factor contributing to breast carcinogenesis and identifies novel molecular mechanisms of regulation the two isoforms of NEAT1., (© 2022. The Author(s).)

Background: Immune checkpoint inhibitors (ICIs) have revolutionized systemic anti-tumor treatments across different types of cancer. Nevertheless, predictive biomarkers regarding treatment response are not routinely established yet. Apart from T-lymphocytes, the humoral immunity of B-lymphocytes is studied to a substantially lesser extent in the respective setting. Thus, the aim of this study was to evaluate peripheral blood B-cell subtypes as potential predictors of ICI treatment response., Methods: Thirty-nine cancer patients receiving ICI therapy were included into this prospective single-center cohort study. All had a first blood draw at the date before treatment initiation and a second at the time of first response evaluation (after 8-12 weeks). Seven different B-cell subtypes were quantified by fluorescence-activated cell sorting (FACS). Disease control- (DCR) and objective response rate (ORR) were co-primary study endpoints., Results: Overall, DCR was 48.7% and ORR was 25.6%, respectively. At baseline, there was no significant association of any B-cell subtype with neither DCR nor ORR. At the first response evaluation, an increase in the frequency of CD21 - B-cells was a statistically significant negative predictor of response, both regarding DCR (OR=0.05, 95%CI=0.00-0.67, p =0.024) and ORR (OR=0.09, 95%CI=0.01-0.96, p =0.046). An increase of the frequency of switched memory B-cells was significantly associated with reduced odds for DCR (OR=0.06, 95%CI=0.01-0.70, p =0.025). Patients with an increased frequency of naïve B-cells were more likely to benefit from ICI therapy as indicated by an improved DCR (OR=12.31, 95%CI=1.13-134.22, p =0.039)., Conclusion: In this study, certain B-cell subpopulations were associated with ICI treatment response in various human cancer types., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Barth, Stanzer, Spiegelberg, Bauernhofer, Absenger, Szkandera, Gerger, Smolle, Hutterer, Ahyai, Madl, Posch, Riedl, Klec, Jost, Kargl, Stradner and Pichler.)

The microRNA-200 family has wide-ranging regulatory functions in cancer development and progression. Above all, it is strongly associated with the epithelial-to-mesenchymal transition (EMT), a process during which cells change their epithelial to a mesenchymal phenotype and acquire invasive characteristics. More recently, miR-200 family members have also been reported to impact the immune evasion of cancer cells by regulating the expression of immunoinhibitory immune checkpoints (ICs) like PD-L1. Therefore, we aimed to comprehensively characterize this miR-200 family as a regulatory interface between EMT and immune evasion mechanisms in biliary tract cancer. Initial correlation analyses and transient overexpression experiments using miRNA mimics suggested miR-200c-3p as a putative regulator of ICs including PD-L1, LGALS9, and IDO1. However, these effects could not be confirmed in stable miR-200c-3p overexpression cell lines, nor in cells transiently transfected with miR-200c-3p mimic from an independent manufacturer. By shifting our efforts towards dissecting the mechanisms leading to these disparate effects, we observed that the initially used miR-200c-3p mimic triggered a double-stranded (ds)RNA-dependent antiviral response. Besides upregulating the ICs, this had substantial cellular consequences including an induction of interferon type I and type III expression, increased levels of intracellular dsRNA sensors, and a significantly altered cellular growth and apoptotic activity.Our study highlights the capability of miRNA mimics to non-specifically induce a dsRNA-mediated antiviral interferon response. Consequently, phenotypic alterations crucially distort physiological miRNA functions and might result in a major misinterpretation of previous and future miRNA studies, especially in the context of IC regulation.

Biliary tract cancer is a major global health issue in cancer-related mortality. Therapeutic options are limited, and cisplatin-based treatment schedules represent the mainstay of first-line therapeutic strategies. Although the gain of survival by the addition of cisplatin to gemcitabine is moderate, acquired cisplatin resistance frequently leads to treatment failures with mechanisms that are still poorly understood. Epithelial-mesenchymal transition (EMT) is a dynamic process that changes the shape, function, and gene expression pattern of biliary tract cancer cells. In this study, we explored the influence of the EMT-regulating miR-200c-3p on cisplatin sensitivity in biliary tract cancer cells. Using gain of function experiments, we demonstrated that miR-200c-3p regulates epithelial cell markers through the downregulation of the transcription factor ZEB1. MiR-200c-3p upregulation led to a decreased sensitivity against cisplatin, as observed in transient overexpression models as well as in cell lines stably overexpressing miR-200c-3p. The underlying mechanism seems to be independent of miR-200c-3p's influence on ZEB1 expression, as ZEB1 knockdown resulted in the opposite effect on cisplatin resistance, which was abolished when ZEB1 knockdown and miR-200c-3p overexpression occurred in parallel. Using a gene panel of 40 genes that were previously associated with cisplatin resistance, two (Dual Specificity Phosphatase 16 ( DUSP16 ) and Stratifin ( SFN )) were identified as significantly (>2 fold, p -value < 0.05) up-regulated in miR-200c-3p overexpressing cells. In conclusion, miR-200c-3p might be an important contributor to cisplatin resistance in biliary tract cancer, independently of its interaction with ZEB1.

Distant metastases are the main cause of cancer-related deaths in patients with advanced tumors. A standard diagnostic workup usually contains the identification of the tissue-of-origin of metastatic tumors, although under certain circumstances, it remains elusive. This disease setting is defined as cancer of unknown primary (CUP). Accounting for approximately 3-5% of all cancer diagnoses, CUPs are characterized by an aggressive clinical behavior and represent a real therapeutic challenge. The lack of determination of a tissue of origin precludes CUP patients from specific evidence-based therapeutic options or access to clinical trial, which significantly impacts their life expectancy. In the era of precision medicine, it is essential to characterize CUP molecular features, including the expression profile of non-coding RNAs, to improve our understanding of CUP biology and identify novel therapeutic strategies. This review article sheds light on this enigmatic disease by summarizing the current knowledge on CUPs focusing on recent discoveries and emerging diagnostic strategies.

The emergence of SARS-CoV-2 in 2019 has caused a major health and economic crisis around the globe. Gaining knowledge about its attributes and interactions with human host cells is crucial. Non-coding RNAs (ncRNAs) are involved in the host cells' innate antiviral immune response. In RNA interference, microRNAs (miRNAs) may bind to complementary sequences of the viral RNA strand, forming an miRNA-induced silencing complex, which destroys the viral RNA, thereby inhibiting viral protein expression. There are several targets for human miRNAs on SARS-CoV-2's RNA, most of which are in the 5' and 3' untranslated regions. Mutations of the viral genome causing the creation or loss of miRNA binding sites may have crucial effects on SARS-CoV-2 pathogenicity. In addition to mediating immunity, the ncRNA landscape of host cells further influences their susceptibility to virus infection, as certain miRNAs are essential in the regulation of cellular receptors that are necessary for virus invasion. Conversely, virus infection also changes the host ncRNA expression patterns, possibly augmenting conditions for viral replication and dissemination. Hence, ncRNAs typically upregulated in SARS-CoV-2 infection could be useful biomarkers for disease progression and severity. Understanding these mechanisms could provide further insight into the pathogenesis and possible treatment options against COVID-19.

Objective: To investigate the function of a novel primate-specific long non-coding RNA (lncRNA), named FLANC, based on its genomic location (co-localised with a pyknon motif), and to characterise its potential as a biomarker and therapeutic target., Design: FLANC expression was analysed in 349 tumours from four cohorts and correlated to clinical data. In a series of multiple in vitro and in vivo models and molecular analyses, we characterised the fundamental biological roles of this lncRNA. We further explored the therapeutic potential of targeting FLANC in a mouse model of colorectal cancer (CRC) metastases., Results: FLANC, a primate-specific lncRNA feebly expressed in normal colon cells, was significantly upregulated in cancer cells compared with normal colon samples in two independent cohorts. High levels of FLANC were associated with poor survival in two additional independent CRC patient cohorts. Both in vitro and in vivo experiments demonstrated that the modulation of FLANC expression influenced cellular growth, apoptosis, migration, angiogenesis and metastases formation ability of CRC cells. In vivo pharmacological targeting of FLANC by administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with a specific small interfering RNA, induced significant decrease in metastases, without evident tissue toxicity or pro-inflammatory effects. Mechanistically, FLANC upregulated and prolonged the half-life of phosphorylated STAT3, inducing the overexpression of VEGFA, a key regulator of angiogenesis., Conclusions: Based on our findings, we discovered, FLANC as a novel primate-specific lncRNA that is highly upregulated in CRC cells and regulates metastases formation. Targeting primate-specific transcripts such as FLANC may represent a novel and low toxic therapeutic strategy for the treatment of patients., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Long non-coding RNAs (lncRNAs) are defined as non-protein coding transcripts with a minimal length of 200 nucleotides. They are involved in various biological processes such as cell differentiation, apoptosis, as well as in pathophysiological processes. Numerous studies considered that frequently deregulated lncRNAs contribute to all hallmarks of cancer including metastasis, drug resistance, and angiogenesis. Angiogenesis, the formation of new blood vessels, is crucial for a tumor to receive sufficient amounts of nutrients and oxygen and therefore, to grow and exceed in its size over the diameter of 2 mm. In this review, the regulatory mechanisms of lncRNAs are described, which influence tumor angiogenesis by directly or indirectly regulating oncogenic pathways, interacting with other transcripts such as microRNAs (miRNAs) or modulating the tumor microenvironment. Further, angiogenic lncRNAs occurring in several cancer types such as liver, gastrointestinal cancer, or brain tumors are summarized. Growing evidence on the influence of lncRNAs on tumor angiogenesis verified these transcripts as potential predictive or diagnostic biomarkers or therapeutic targets of anti-angiogenesis treatment. However, there are many unsolved questions left which are pointed out in this review, hence driving comprehensive research in this area is necessary to enable an effective use of lncRNAs as either therapeutic molecules or diagnostic targets in cancer.

Hypoxia is dangerous for oxygen-dependent cells, therefore, physiological adaption to cellular hypoxic conditions is essential. The transcription factor hypoxia-inducible factor (HIF) is the main regulator of hypoxic metabolic adaption reducing oxygen consumption and is regulated by gradual von Hippel-Lindau (VHL)-dependent proteasomal degradation. Beyond physiology, hypoxia is frequently encountered within solid tumors and first drugs are in clinical trials to tackle this pathway in cancer. Besides hypoxia, cancer cells may promote HIF expression under normoxic conditions by altering various upstream regulators, cumulating in HIF upregulation and enhanced glycolysis and angiogenesis, altogether promoting tumor proliferation and progression. Therefore, understanding the underlying molecular mechanisms is crucial to discover potential future therapeutic targets to evolve cancer therapy. Long non-coding RNAs (lncRNA) are a class of non-protein coding RNA molecules with a length of over 200 nucleotides. They participate in cancer development and progression and might act as either oncogenic or tumor suppressive factors. Additionally, a growing body of evidence supports the role of lncRNAs in the hypoxic and normoxic regulation of HIF and its subunits HIF-1α and HIF-2α in cancer. This review provides a comprehensive update and overview of lncRNAs as regulators of HIFs expression and activation and discusses and highlights potential involved pathways.

POU3F3 adjacent non-coding transcript 1 (PANTR1) is an oncogenic long non-coding RNA with significant influence on numerous cellular features in different types of cancer. No characterization of its role in renal cell carcinoma (RCC) is yet available. In this study, PANTR1 expression was confined to human brain and kidney tissue and was found significantly up-regulated in clear-cell renal cell carcinoma tissue (ccRCC) compared to non-cancerous kidney tissue in two independent cohorts ( p < 0.001 for both cohorts). In uni- and multivariate Cox regression analysis, ccRCC patients with higher levels of PANTR1 showed significantly poorer disease-free survival in our own respective cohort ( n = 175, hazard ratio: 4.3, 95% confidence interval: 1.45-12.75, p = 0.008) in accordance with significantly poorer overall survival in a large The Cancer Genome Atlas database (TCGA) cohort ( n = 530, hazard ratio: 2.19, 95% confidence interval: 1.59-3.03, p ≤ 0.001). To study the underlying cellular mechanisms mediated by varying levels of PANTR1 in kidney cancer cells, we applied siRNA-mediated knock-down experiments in three independent ccRCC cell lines (RCC-FG, RCC-MF, 769-P). A decrease in PANTR1 levels led to significantly reduced cellular growth through activation of apoptosis in all tested cell lines. Moreover, as angiogenesis is a critical driver in ccRCC pathogenesis, we identified that PANTR1 expression is critical for in vitro tube formation and endothelial cell migration ( p < 0.05). On the molecular level, knock-down of PANTR1 led to a decrease in Vascular Endothelial growth factor A (VEGF-A) and cell adhesion molecule laminin subunit gamma-2 (LAMC2) expression, corroborated by a positive correlation in RCC tissue (for VEGF-A R = 0.19, p < 0.0001, for LAMC2 R = 0.13, p = 0.0028). In conclusion, this study provides first evidence that PANTR1 has a relevant role in human RCC by influencing apoptosis and angiogenesis.

Pancreatic beta (β) cell dysfunction results in compromised insulin release and, thus, failed regulation of blood glucose levels. This forms the backbone of the development of diabetes mellitus (DM), a disease that affects a significant portion of the global adult population. Physiological calcium (Ca 2+ ) signaling has been found to be vital for the proper insulin-releasing function of β-cells. Calcium dysregulation events can have a dramatic effect on the proper functioning of the pancreatic β-cells. The current review discusses the role of calcium signaling in health and disease in pancreatic β-cells and provides an in-depth look into the potential role of alterations in β-cell Ca 2+ homeostasis and signaling in the development of diabetes and highlights recent work that introduced the current theories on the connection between calcium and the onset of diabetes.

Renal cell carcinoma (RCC) is a relatively rare malignancy of the urinary tract system. RCC is a heterogenous disease in terms of underlying histology and its associated underlying pathobiology, prognosis and treatment schedule. The most prevalent histological RCC subtype is clear-cell renal cell carcinoma (ccRCC), accounting for about 70-80% of all RCCs. Though the pathobiology and treatment schedule for ccRCC are well-established, non-ccRCC subtypes account for 20%-30% of RCC altogether, and their underlying molecular biology and treatment options are poorly defined. The class of non-coding RNAs-molecules that are generally not translated into proteins-are new cancer drivers and suppressors in all types of cancer. Of these, small non-coding microRNAs (miRNAs) contribute to carcinogenesis by regulating posttranscriptional gene silencing. Additionally, a growing body of evidence supports the role of long non-coding RNAs (lncRNAs) in cancer development and progression. Most studies on non-coding RNAs in RCC focus on clear-cell histology, and there is a relatively limited number of studies on non-ccRCC subtypes. The aim of this review is to give an overview of the current knowledge regarding the role of non-coding RNAs (including short and long non-coding RNAs) in non-ccRCC and to highlight possible implications as diagnostic, prognostic and predictive biomarkers.

Mitochondrial Ca 2+ uptake into the mitochondrial matrix is a well-established mechanism. However, the sub-organellar Ca 2+ kinetics remain elusive. In the present work we identified novel site-specific targeting sequences for the intermembrane space (IMS) and the cristae lumen (CL). We used these novel targeting peptides to develop green- and red- Ca 2+ biosensors targeted to the IMS and to the CL. Based on their distinctive spectral properties, and comparable sensitivities these novel constructs were suitable to visualize Ca 2+ -levels in various (sub) compartments in a multi-chromatic manner. Functional studies that applied these new biosensors revealed that knockdown of MCU and EMRE yielded elevated Ca 2+ levels inside the CL but not the IMS in response to IP 3 -generating agonists. Knockdown of VDAC1, however, strongly impeded the transfer of Ca 2+ through the OMM while the cytosolic Ca 2+ signal remained unchanged. The novel sub-mitochondrially targeted Ca 2+ biosensors proved to be suitable for Ca 2+ imaging with high spatial and temporal resolution in a multi-chromatic manner allowing simultaneous measurements. These informative biosensors will facilitate efforts to dissect the complex sub-mitochondrial Ca 2+ signaling under (patho)physiological conditions., (Copyright © 2019 Waldeck-Weiermair, Gottschalk, Madreiter-Sokolowski, Ramadani-Muja, Ziomek, Klec, Burgstaller, Bischof, Depaoli, Eroglu, Malli and Graier.)

Recently identified core proteins (MICU1, MCU, EMRE) forming the mitochondrial Ca 2+ uniporter complex propelled investigations into its physiological workings. Here, we apply structured illumination microscopy to visualize and localize these proteins in living cells. Our data show that MICU1 localizes at the inner boundary membrane (IBM) due to electrostatic interaction of its polybasic domain. Moreover, this exclusive localization of MICU1 is important for the stability of cristae junctions (CJ), cytochrome c release and mitochondrial membrane potential. In contrast to MICU1, MCU and EMRE are homogeneously distributed at the inner mitochondrial membrane under resting conditions. However, upon Ca 2+ elevation MCU and EMRE dynamically accumulate at the IBM in a MICU1-dependent manner. Eventually, our findings unveil an essential function of MICU1 in CJ stabilization and provide mechanistic insights of how sophistically MICU1 controls the MCU-Complex while maintaining the structural mitochondrial membrane framework.

Introduction: HULC (highly upregulated in liver cancer) is a long non-coding RNA (lncRNA) which is, as its name suggests, highly upregulated in hepatocellular carcinoma and in several other cancers. Increased HULC expression levels are strongly associated with clinicopathologic features such as tumor stages and overall survival and is a driver of tumor proliferation, migration, and invasion. Areas covered: This review addresses the discovery of HULC and discusses the consequences of HULC deregulation in cancer, the underlying molecular mechanisms and the potential of HULC as a biomarker and therapeutic target. Expert opinion: HULC is a promising candidate as a therapeutic target in cancer; however, more studies are necessary to further elucidate the underlying molecular mechanism(s), especially in cancer types other than hepatocellular carcinomas. Future studies that focus on an optimized HULC-targeting approach are necessary to clarify the best strategy to target this lncRNA in vivo and in patients.

Background: Non-coding RNAs and especially microRNAs have been discovered to act as master regulators of cancer initiation and progression. The aim of our study was to discover and characterize the function of yet functionally uncharacterized microRNAs in human breast carcinogenesis., Methods: In an unbiased approach, we utilized an established model system for breast cancer (BC) stem cell formation ("mammosphere assay") to identify whole miRNome alterations in breast carcinogenesis. Clinical samples of BC patients were used to evaluate the human relevance of the newly identified miRNA candidates. One promising candidate, miR-1287-5p, was further explored on its impact on several hallmarks of cancer. The molecular mode of action was characterized by whole transcriptome analysis, in silico prediction tools, miRNA-interaction assays, pheno-copy assays, and drug sensitivity assays., Results: Among several other microRNAs, miR-1287-5p was significantly downregulated in mammospheres and human BC tissue compared to normal breast tissue (p < 0.0001). Low expression levels were significantly associated with poor prognosis in BC patients. MiR-1287-5p significantly decreased cellular growth, cells in S phase of cell cycle, anchorage-independent growth, and tumor formation in vivo. In addition, we identified PIK3CB as a direct molecular interactor of miR-1287-5p and a novel prognostic factor in BC. Finally, PI3Kinase pathway chemical inhibitors combined with miR-1287-5p mimic increased the pharmacological growth inhibitory potential in triple negative BC cells., Conclusion: Our data identified for the first time the involvement of miR-1287-5p in human BC and suggest a potential for therapeutic interventions in difficult to treat triple negative BC.

Long non-coding RNAs (lncRNAs) are involved in a variety of biological and cellular processes as well as in physiologic and pathophysiologic events. This review summarizes recent literature about the role of the lncRNA nuclear enriched abundant transcript 1 ( NEAT1 ) in non-cancerous diseases with a special focus on viral infections and neurodegenerative diseases. In contrast to its role as competing endogenous RNA (ceRNA) in carcinogenesis, NEAT1 's function in non-cancerous diseases predominantly focuses on paraspeckle-mediated effects on gene expression. This involves processes such as nuclear retention of mRNAs or sequestration of paraspeckle proteins from specific promoters, resulting in transcriptional induction or repression of genes involved in regulating the immune system or neurodegenerative processes. NEAT1 expression is aberrantly-mostly upregulated-in non-cancerous pathological conditions, indicating that it could serve as potential prognostic biomarker. Additional studies are needed to elucidate NEAT1 's capability to be a therapeutic target for non-cancerous diseases.

Lipid-gated TRPC channels are highly expressed in cardiovascular and neuronal tissues. Exerting precise pharmacological control over their activity in native cells is expected to serve as a basis for the development of novel therapies. Here we report on a new photopharmacological tool that enables manipulation of TRPC3 channels by light, in a manner independent of lipid metabolism and with higher temporal precision than lipid photopharmacology. Using the azobenzene photoswitch moiety, we modified GSK1702934A to generate light-controlled TRPC agonists. We obtained one light-sensitive molecule (OptoBI-1) that allows us to exert efficient, light-mediated control over TRPC3 activity and the associated cellular Ca 2+ signaling. OptoBI-1 enabled high-precision, temporal control of TRPC3-linked cell functions such as neuronal firing and endothelial Ca 2+ transients. With these findings, we introduce a novel photopharmacological strategy to control native TRPC conductances.

Background/aims: In our recent work, the importance of GSK3β-mediated phosphorylation of presenilin-1 as crucial process to establish a Ca 2+ leak in the endoplasmic reticulum and, subsequently, the pre-activation of resting mitochondrial activity in β-cells was demonstrated. The present work is a follow-up and reveals the importance of GSK3β-phosphorylated presenilin-1 for responsiveness of pancreatic islets and β-cells to elevated glucose in terms of cytosolic Ca 2+ spiking and insulin secretion., Methods: Freshly isolated pancreatic islets and the two pancreatic β-cell lines INS-1 and MIN-6 were used. Cytosolic Ca 2+ was fluorometrically monitored using Fura-2/AM and cellular insulin content and secretion were measured by ELISA., Results: Our data strengthened our previous findings of the existence of a presenilin-1-mediated ER-Ca 2+ leak in β-cells, since a reduction of presenilin-1 expression strongly counteracted the ER Ca 2+ leak. Furthermore, our data revealed that cytosolic Ca 2+ spiking upon administration of high D-glucose was delayed in onset time and strongly reduced in amplitude and frequency upon siRNA-mediated knock-down of presenilin-1 or the inhibition of GSK3β in the pancreatic β-cells. Moreover, glucose-triggered initial insulin secretion disappeared by depletion from presenilin-1 and inhibition of GSK3β in the pancreatic β-cells and isolated pancreatic islets, respectively., Conclusion: These data complement our previous work and demonstrate that the sensitivity of pancreatic islets and β-cells to glucose illustrated as glucose-triggered cytosolic Ca 2+ spiking and initial but not long-lasting insulin secretion crucially depends on a strong ER Ca 2+ leak that is due to the phosphorylation of presenilin-1 by GSK3β, a phenomenon that might be involved in the development of type 2 diabetes., Competing Interests: The authors declare no competing financial interests., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)

Altered expression levels of the long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) have been reported in different types of cancer. More than half of the NEAT1 studies in cancer have been published within the last 2 years. In this review, we discuss very recent developments and insights into NEAT1 contribution to carcinogenesis. Summarizing the literature, it becomes obvious that NEAT1 is a lncRNA highly de-/upregulated in a variety of cancer entities, in which it primarily acts as a competing endogenous RNA (ceRNA) which sponges tumor-suppressive microRNA (miRNA). The sponged miRNA lose their ability to degrade, silence, or hamper translation of their downstream-mostly oncogenic-target transcripts, ultimately promoting carcinogenesis. This role of NEAT1 function in tumorigenesis suggests it may be a prognostic biomarker as well as potential therapeutic target, pending the completion of further studies into the underlying mechanisms., (© 2018 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

Background: Senescence is characterized by a gradual decline in cellular functions, including changes in energy homeostasis and decreased proliferation activity. As cellular power plants, contributors to signal transduction, sources of reactive oxygen species (ROS) and executors of programmed cell death, mitochondria are in a unique position to affect aging-associated processes of cellular decline. Notably, metabolic activation of mitochondria is tightly linked to Ca 2+ due to the Ca 2+ -dependency of several enzymes in the Krebs cycle, however, overload of mitochondria with Ca 2+ triggers cell death pathways. Consequently, a machinery of proteins tightly controls mitochondrial Ca 2+ homeostasis as well as the exchange of Ca 2+ between the different cellular compartments, including Ca 2+ flux between mitochondria and the endoplasmic reticulum (ER)., Methods: In this study, we investigated age-related changes in mitochondrial Ca 2+ homeostasis, mitochondrial-ER linkage and the activity of the main ROS production site, the mitochondrial respiration chain, in an in vitro aging model based on porcine aortic endothelial cells (PAECs), using high-resolution live cell imaging, proteomics and various molecular biological methods., Results: We describe that in aged endothelial cells, increased ER-mitochondrial Ca 2+ crosstalk occurs due to enhanced ER-mitochondrial tethering. The close functional inter-organelle linkage increases mitochondrial Ca 2+ uptake and thereby the activity of the mitochondrial respiration, but also makes senescent cells more vulnerable to mitochondrial Ca 2+ -overload-induced cell death. Moreover, we identified the senolytic properties of the polyphenol resveratrol, triggering cell death via mitochondrial Ca 2+ overload exclusively in senescent cells., Conclusion: By unveiling aging-related changes in the inter-organelle tethering and Ca 2+ communications we have advanced the understanding of endothelial aging and highlighted a potential basis to develop drugs specifically targeting senescent cells., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Background/aims: In pancreatic β-cells, the intracellular Ca²⁺ homeostasis is an essential regulator of the cells major functions. The endoplasmic reticulum (ER) as interactive intracellular Ca²⁺ store balances cellular Ca²⁺. In this study basal ER Ca²⁺ homeostasis was evaluated in order to reveal potential β-cell-specificity of ER Ca²⁺ handling and its consequences for mitochondrial Ca²⁺, ATP and respiration., Methods: The two pancreatic cell lines INS-1 and MIN-6, freshly isolated pancreatic islets, and the two non-pancreatic cell lines HeLA and EA.hy926 were used. Cytosolic, ER and mitochondrial Ca²⁺ and ATP measurements were performed using single cell fluorescence microscopy and respective (genetically-encoded) sensors/dyes. Mitochondrial respiration was monitored by respirometry. GSK3β activity was measured with ELISA., Results: An atypical ER Ca²⁺ leak was observed exclusively in pancreatic islets and β-cells. This continuous ER Ca²⁺ efflux is directed to mitochondria and increases basal respiration and organellar ATP levels, is established by GSK3β-mediated phosphorylation of presenilin-1, and is prevented by either knockdown of presenilin-1 or an inhibition/knockdown of GSK3β. Expression of a presenlin-1 mutant that mimics GSK3β-mediated phosphorylation established a β-cell-like ER Ca²⁺ leak in HeLa and EA.hy926 cells. The ER Ca²⁺ loss in β-cells was compensated at steady state by Ca²⁺ entry that is linked to the activity of TRPC3., Conclusion: Pancreatic β-cells establish a cell-specific ER Ca²⁺ leak that is under the control of GSK3β and directed to mitochondria, thus, reflecting a cell-specific intracellular Ca²⁺ handling for basal mitochondrial activity., Competing Interests: The authors declare no competing financial interests., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)

Metastatic testicular germ cell tumors (TGCTs) are a potentially curable disease by administration of risk-adapted cytotoxic chemotherapy. Nevertheless, a disease-relapse after curative chemotherapy needs more intensive salvage chemotherapy and significantly worsens the prognosis of TGCT patients. Circulating tumor markers (β-subunit of human chorionic gonadotropin (β-HCG), alpha-Fetoprotein (AFP), and Lactate Dehydrogenase (LDH)) are frequently used for monitoring disease recurrence in TGCT patients, though they lack diagnostic sensitivity and specificity. Increasing evidence suggests that serum levels of stem cell-associated microRNAs (miR-371a-3p and miR-302/367 cluster) are outperforming the traditional tumor markers in terms of sensitivity to detect newly diagnosed TGCT patients. The aim of this study was to investigate whether these miRNAs are also informative in detection of disease recurrence in TGCT patients after curative first line therapy. For this purpose, we measured the serum levels of miR-371a-3p and miR-367 in 52 samples of ten TGCT patients at different time points during disease relapse and during salvage chemotherapy. In our study, miR-371a-3p levels in serum samples with proven disease recurrence were 13.65 fold higher than levels from the same patients without evidence of disease ( p = 0.014). In contrast, miR-367 levels were not different in these patient groups ( p = 0.985). In conclusion, miR-371a-3p is a sensitive and potentially novel biomarker for detecting disease relapse in TGCT patients. This promising biomarker should be investigated in further large prospective trials.

Reprogramming of metabolic pathways determines cell functions and fate. In our work, we have used organelle-targeted ATP biosensors to evaluate cellular metabolic settings with high resolution in real time. Our data indicate that mitochondria dynamically supply ATP for glucose phosphorylation in a variety of cancer cell types. This hexokinase-dependent process seems to be reversed upon the removal of glucose or other hexose sugars. Our data further verify that mitochondria in cancer cells have increased ATP consumption. Similar subcellular ATP fluxes occurred in young mouse embryonic fibroblasts (MEFs). However, pancreatic beta cells, senescent MEFs, and MEFs lacking mitofusin 2 displayed completely different mitochondrial ATP dynamics, indicative of increased oxidative phosphorylation. Our findings add perspective to the variability of the cellular bioenergetics and demonstrate that live cell imaging of mitochondrial ATP dynamics is a powerful tool to evaluate metabolic flexibility and heterogeneity at a single-cell level., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

Mitochondria are multifunctional organelles that essentially contribute to cell signaling by sophisticated mechanisms of communications. Live cell imaging studies showed that mitochondria are dynamic and complex structures that form ramified networks by directed movements, fission, and fusion events. There is emerging evidence that the morphology of mitochondria determines cellular functions and vice versa. Several intracellular signaling pathways and messengers including Ca 2+ dynamically influence the architecture of mitochondria. Because electron microscopy cannot be utilized for an assessment of dynamics of mitochondrial morphology in intact cells, most studies were performed using wide-field or laser confocal fluorescence microscopies that, due to limitations of their spatial resolution, do not allow investigating sub-mitochondrial structures. Accordingly, our understanding of the dynamics of substructures of mitochondria is quite limited. Here, we present a robust super-resolution method to quantify the dynamics of mitochondrial cristae, the main substructures of the inner mitochondrial membrane, exploiting structured illumination microscopy (SIM). We observed that knockdown of the dynamin-like 120-kDa protein, which is encoded by the OPA1 gene, specifically reduces the dynamics of the mitochondrial cristae membranes (CM), while the inner boundary membrane (IBM) remained flexible. We further used dual color SIM to quantify the dynamics of CM in the junction between mitochondria and the endoplasmic reticulum (ER; mitochondrial associated membranes, MAMs). Intracellular Ca 2+ release spatially reduced CM-dynamics in MAMs. Moreover, CM-dynamics was independent from matrix Ca 2+ signal. Our data suggest that local Ca 2+ signals specifically control CM-dynamics and structure to facilitate a well-balanced functional (Ca 2+ ) interplay between mitochondria and the ER.

Cancer cells have developed unique strategies to meet their high energy demand. Therefore, they have established a setting of Ca 2+ -triggered high mitochondrial activity. But mitochondrial Ca 2+ uptake has to be strictly controlled to avoid mitochondrial Ca 2+ overload that would cause apoptotic cell death. Methylation by protein arginine methyl transferase 1 (PRMT1) desensitizes the mitochondrial Ca 2+ uptake machinery and reduces mitochondrial Ca 2+ accumulation in cancer cells. In case of PRMT1-driven methylation, proper mitochondrial Ca 2+ uptake is reestablished by increased activity of uncoupling protein 2 (UCP2), pointing to an importance of these proteins for cancer cell survival and activity. Accordingly, in this study we investigated the impact of UCP2 and PRMT1 on the fate of human lung cancer cells (A549, Calu-3 and H1299) as well as on patients suffering from lung carcinoma. We show that combined overexpression of UCP2 and PRMT1 significantly enhances viability, proliferation as well as mitochondrial respiration. In line with these findings, the overall survival probability of lung carcinoma patients with high mRNA expression levels of UCP2 and PRMT1 is strongly reduced. Furthermore, analysis via The Cancer Genome Atlas (TCGA) reveals upregulation of both proteins, UCP2 and PRMT1, as common feature of various cancer types. These findings suggest that proper mitochondrial Ca 2+ uptake is essential for devastating tumor growth, and highlight the importance of a tightly controlled mitochondrial Ca 2+ uptake to ensure proper ATP biosynthesis while avoiding dangerous mitochondrial Ca 2+ overload. By that, the study unveils proteins of the mitochondrial Ca 2+ uptake as potential targets for cancer treatment., Competing Interests: CONFLICTS OF INTEREST The authors have no conflicts of interest to declare.

Nitric Oxide (NO•) is a small radical, which mediates multiple important cellular functions in mammals, bacteria and plants. Despite the existence of a large number of methods for detecting NO• in vivo and in vitro, the real-time monitoring of NO• at the single-cell level is very challenging. The physiological or pathological effects of NO• are determined by the actual concentration and dwell time of this radical. Accordingly, methods that allow the single-cell detection of NO• are highly desirable. Recently, we expanded the pallet of NO• indicators by introducing single fluorescent protein-based genetically encoded nitric oxide (NO•) probes (geNOps) that directly respond to cellular NO• fluctuations and, hence, addresses this need. Here we demonstrate the usage of geNOps to assess intracellular NO• signals in response to two different chemical NO•-liberating molecules. Our results also confirm that freshly prepared 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC-7) has a much higher potential to evoke change in intracellular NO• levels as compared with the inorganic NO• donor sodium nitroprusside (SNP). Furthermore, dual-color live-cell imaging using the green geNOps (G-geNOp) and the chemical Ca 2+ indicator fura-2 was performed to visualize the tight regulation of Ca 2+ -dependent NO• formation in single endothelial cells. These representative experiments demonstrate that geNOps are suitable tools to investigate the real-time generation and degradation of single-cell NO• signals in diverse experimental setups.

Recent studies revealed that mitochondrial Ca(2+) channels, which control energy flow, cell signalling and death, are macromolecular complexes that basically consist of the pore-forming mitochondrial Ca(2+) uniporter (MCU) protein, the essential MCU regulator (EMRE), and the mitochondrial Ca(2+) uptake 1 (MICU1). MICU1 is a regulatory subunit that shields mitochondria from Ca(2+) overload. Before the identification of these core elements, the novel uncoupling proteins 2 and 3 (UCP2/3) have been shown to be fundamental for mitochondrial Ca(2+) uptake. Here we clarify the molecular mechanism that determines the UCP2/3 dependency of mitochondrial Ca(2+) uptake. Our data demonstrate that mitochondrial Ca(2+) uptake is controlled by protein arginine methyl transferase 1 (PRMT1) that asymmetrically methylates MICU1, resulting in decreased Ca(2+) sensitivity. UCP2/3 normalize Ca(2+) sensitivity of methylated MICU1 and, thus, re-establish mitochondrial Ca(2+) uptake activity. These data provide novel insights in the complex regulation of the mitochondrial Ca(2+) uniporter by PRMT1 and UCP2/3.

Background/aims: Resveratrol and its derivate piceatannol are known to induce cancer cell-specific cell death. While multiple mechanisms of actions have been described including the inhibition of ATP synthase, changes in mitochondrial membrane potential and ROS levels, the exact mechanisms of cancer specificity of these polyphenols remain unclear. This paper is designed to reveal the molecular basis of the cancer-specific initiation of cell death by resveratrol and piceatannol., Methods: The two cancer cell lines EA.hy926 and HeLa, and somatic short-term cultured HUVEC were used. Cell viability and caspase 3/7 activity were tested. Mitochondrial, cytosolic and endoplasmic reticulum Ca2+ as well as cytosolic and mitochondrial ATP levels were measured using single cell fluorescence microscopy and respective genetically-encoded sensors. Mitochondria-ER junctions were analyzed applying super-resolution SIM and ImageJ-based image analysis., Results: Resveratrol and piceatannol selectively trigger death in cancer but not somatic cells. Hence, these polyphenols strongly enhanced mitochondrial Ca2+ uptake in cancer exclusively. Resveratrol and piceatannol predominantly affect mitochondrial but not cytosolic ATP content that yields in a reduced SERCA activity. Decreased SERCA activity and the strongly enriched tethering of the ER and mitochondria in cancer cells result in an enhanced MCU/Letm1-dependent mitochondrial Ca2+ uptake upon intracellular Ca2+ release exclusively in cancer cells. Accordingly, resveratrol/piceatannol-induced cancer cell death could be prevented by siRNA-mediated knock-down of MCU and Letm1., Conclusions: Because their greatly enriched ER-mitochondria tethering, cancer cells are highly susceptible for resveratrol/piceatannol-induced reduction of SERCA activity to yield mitochondrial Ca2+ overload and subsequent cancer cell death., (© 2016 The Author(s) Published by S. Karger AG, Basel.)

Mitochondrial Ca(2+) uptake is a vital process that controls distinct cell and organelle functions. Mitochondrial calcium uptake 1 (MICU1) was identified as key regulator of the mitochondrial Ca(2+) uniporter (MCU) that together with the essential MCU regulator (EMRE) forms the mitochondrial Ca(2+) channel. However, mechanisms by which MICU1 controls MCU/EMRE activity to tune mitochondrial Ca(2+) signals remain ambiguous. Here we established a live-cell FRET approach and demonstrate that elevations of cytosolic Ca(2+) rearranges MICU1 multimers with an EC50 of 4.4 μM, resulting in activation of mitochondrial Ca(2+) uptake. MICU1 rearrangement essentially requires the EF-hand motifs and strictly correlates with the shape of cytosolic Ca(2+) rises. We further show that rearrangements of MICU1 multimers were independent of matrix Ca(2+) concentration, mitochondrial membrane potential, and expression levels of MCU and EMRE. Our experiments provide novel details about how MCU/EMRE is regulated by MICU1 and an original approach to investigate MCU/EMRE activation in intact cells.

Cameleons are sophisticated genetically encoded fluorescent probes that allow quantifying cellular Ca2+ signals. The probes are based on Förster resonance energy transfer (FRET) between terminally located fluorescent proteins (FPs), which move together upon binding of Ca2+ to the central calmodulin myosin light chain kinase M13 domain. Most of the available cameleons consist of cyan and yellow FPs (CFP and YFP) as the FRET pair. However, red-shifted versions with green and orange or red FPs (GFP, OFP, RFP) have some advantages such as less phototoxicity and minimal spectral overlay with autofluorescence of cells and fura-2, a prominent chemical Ca2+ indicator. While GFP/OFP- or GFP/RFP-based cameleons have been successfully used to study cytosolic and mitochondrial Ca2+ signals, red-shifted cameleons to visualize Ca2+ dynamics of the endoplasmic reticulum (ER) have not been developed so far. In this study, we generated and tested several ER targeted red-shifted cameleons. Our results show that GFP/OFP-based cameleons due to miss-targeting and their high Ca2+ binding affinity are inappropriate to record ER Ca2+ signals. However, ER targeted GFP/RFP-based probes were suitable to sense ER Ca2+ in a reliable manner. With this study we increased the palette of cameleons for visualizing Ca2+ dynamics within the main intracellular Ca2+ store.

Anandamide (N-arachidonyl ethanolamide, AEA) is an endogenous cannabinoid that is involved in various pathological conditions, including cardiovascular diseases and tumor-angiogenesis. Herein, we tested the involvement of classical cannabinoid receptors (CBRs) and the Ca(2+)-channel transient receptor potential vanilloid 1 (TRPV1) on cellular AEA uptake and its effect on endothelial cell proliferation and network-formation. Uptake of the fluorescence-labeled anandamide (SKM4-45-1) was monitored in human endothelial colony-forming cells (ECFCs) and a human endothelial-vein cell line (EA.hy926). Involvement of the receptors during AEA translocation was determined by selective pharmacological inhibition (AM251, SR144528, CID16020046, SB366791) and molecular interference by TRPV1-selective siRNA-mediated knock-down and TRPV1 overexpression. We show that exclusively TRPV1 contributes essentially to AEA transport into endothelial cells in a Ca(2+)-independent manner. This TRPV1 function is a prerequisite for AEA-induced endothelial cell proliferation and network-formation. Our findings point to a so far unknown moonlighting function of TRPV1 as Ca(2+)-independent contributor/regulator of AEA uptake. We propose TRPV1 as representing a promising target for development of pharmacological therapies against AEA-triggered endothelial cell functions, including their stimulatory effect on tumor-angiogenesis., (© 2014. Published by The Company of Biologists Ltd.)