Cell-specific Manner Research Articles

Abstract A46: A bone marrow vascular niche model to study the effects of a DNA Damage Secretory Program in promoting prostate cancer treatment resistance

Abstract Introduction: Prostate cancer (PC) and other solid tumors generally demonstrate initial responses to genotoxic therapeutics, including chemotherapy and radiotherapy. However, for metastatic cancers, resistance to these modalities occurs predictably. Whereas therapeutic strategies for metastatic disease often rely on DNA-damaging agents, our recent work has demonstrated that normal cells comprising the prostate tumor microenvironment are crucial regulators of cancer cell responses to therapy. These studies indicated that the activation of a DNA-Damage Secretory Phenotype (DDSP) within prostate stroma is a critical mediator of acquired tumor resistance to therapy. However, it is not known whether the bone microenvironment also provides a chemoresistant niche to disseminated cells. Here, we aim to test the hypothesis that activation of the DDSP in the bone microenvironment influences tumor cell proliferation and resistance to genotoxic cancer therapeutics. Methods: To test this hypothesis, we established a cell culture model of the vascular niche, since recent evidence demonstrates that endothelial cells play an important role in the formation of metastatic niches, where they regulate dormancy, proliferation and survival of disseminated cells. We co-cultured endothelial cells with primary human bone marrow derived mesenchymal stem cells (hBM-MSC) to obtain stable 3-dimensional microvascular networks. This organotypic model of bone marrow-like vasculature was then subjected to escalating doses of γ-radiation (Cs-137; 0, 2 and 10Gy), further seeded with PC cell lines (PC3, 22RV1 and LNCaP C4-2B) and we measured proliferation rates of PC cells. Responses to cancer therapeutics (carboplatin at 0, 1, 10 and 100μM or mitoxantrone at 0, 1, 10 and 100nM) were also established using the same model. Results: We determined that following γ-radiation of the stromal components, tumor cell proliferation rates differed depending on the composition of the constructed niche. Although variation in responses was observed between prostate cancer cell lines, PC3 cells showed an increase in proliferation on irradiated vascular niche (10Gy), with an average of 17±3 Ki-67 positive cells per cluster as compared to 7±3 Ki-67 positive cells per cluster when seeded on irradiated control hBM-MSC for 10 days. To evaluate the contribution of the vascular niche to tumor resistance to therapy, PC cells seeded on vascular networks were subjected to treatments with carboplatin or mitoxantrone. The relative area of tumor cells for each well was calculated from live-cell imaging and apoptosis was assayed by TUNEL reaction. Mitoxantrone-treated 22RV1 cells showed decreased apoptosis when seeded on vascular niches (% Apoptosis: 6±2 at 100nM mitoxantrone) as opposed cells seeded on control hBM-MSC (% Apoptosis: 14±3 at 100nM mitoxantrone). Conclusions: These studies suggest that effectors derived from the bone marrow vascular niche are differentially regulated following DNA-damage. Subsequently, those factors may influence tumor cell proliferation and/or resistance to therapy, but may do so in a tumor cell-specific manner. Characterization of the DDSP from the vascular niche could potentially unravel mechanisms of treatment resistance and tumor progression. Citation Format: Christine Levesque, Xin Zhao, Cyrus M. Ghajar, Peter S. Nelson. A bone marrow vascular niche model to study the effects of a DNA Damage Secretory Program in promoting prostate cancer treatment resistance. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A46.

Inhibition of mitochondrial 2-oxoglutarate dehydrogenase impairs viability of cancer cells in a cell-specific metabolism-dependent manner.

2-Oxoglutarate dehydrogenase (OGDH) of the tricarboxylic acid (TCA) cycle is often implied to be inactive in cancer, but this was not experimentally tested. We addressed the question through specific inhibition of OGDH by succinyl phosphonate (SP). SP action on different cancer cells was investigated using indicators of cellular viability and reactive oxygen species (ROS), metabolic profiling and transcriptomics. Relative sensitivity of various cancer cells to SP changed with increasing SP exposure and could differ in the ATP- and NAD(P)H-based assays. Glioblastoma responses to SP revealed metabolic sub-types increasing or decreasing cellular ATP/NAD(P)H ratio under OGDH inhibition. Cancer cell homeostasis was perturbed also when viability indicators were SP-resistant, e.g. in U87 and N2A cells. The transcriptomics database analysis showed that the SP-sensitive cells, such as A549 and T98G, exhibit the lowest expression of OGDH compared to other TCA cycle enzymes, associated with higher expression of affiliated pathways utilizing 2-oxoglutarate. Metabolic profiling confirmed the dependence of cellular SP reactivity on cell-specific expression of the pathways. Thus, oxidative decarboxylation of 2-oxoglutarate is significant for the interdependent homeostasis of NAD(P)H, ATP, ROS and key metabolites in various cancer cells. Assessment of cell-specific responses to OGDH inhibition is of diagnostic value for anticancer strategies.

Tumor Necrosis Factor Receptor Associated Factors (TRAFs) 2 and 3 Form a Transcriptional Complex with Phosho-RNA Polymerase II and p65 in CD40 Ligand Activated Neuro2a Cells

The tumor necrosis factor receptor-associated factors (TRAFs) have been classically described as adaptor proteins that function as solely cytosolic signaling intermediates for the TNF receptor superfamily, Toll-like receptors (TLRs), NOD, like receptors (NLRs), cytokine receptors, and others. In this study, we show for the first time that TRAFs are present within the cytoplasm and nucleus of Neuro2a cells and primary cortical neurons, and that TRAF2 and TRAF3 translocate into the nucleus within minutes of CD40L stimulation. Analysis of the transcriptional regulatory potential of TRAFs by luciferase assay revealed that each of the TRAFs differentially functions as a transcriptional activator or repressor in a cell-specific manner. Interestingly, ChIP-qPCR data demonstrate that TRAFs 2/3, p65, and pRNAPol II form part of a transcriptional complex on the Icam-1 gene promoter upon CD40L stimulation. We further determined that TRAF2 recruitment to the nucleus is critical for the ubiquitination of H2b, a transcription permissive epigenetic modification. Our findings demonstrate for the first time that TRAFs 2/3 participate in the formation of a CD40L-induced transcriptional complex in neuronal cells.

HIV-1 Infection Dysregulates Cell Cycle Regulatory Protein p21 in CD4+ T Cells Through miR-20a and miR-106b Regulation.

Both CD4+ T lymphocytes and macrophages are the major targets of human immunodeficiency virus type 1 (HIV-1); however, they respond differently to HIV-1 infection. We hypothesized that HIV-1 infection alters gene expression in CD4+ T cells and monocyte-derived macrophages (MDMs) in a cell specific manner and microRNAs (miRNAs) in part play a role in cell-specific gene expression. Results indicate that 183 and 31 genes were differentially regulated in HIV-1 infected CD4+ T cells and MDMs, respectively, compared to their mock-infected counterparts. Among the differentially expressed genes, cell cycle regulatory gene, p21 (CDKN1A) was upregulated in virus infected CD4+ T cells both at the mRNA and protein level in CD4+ T cells, whereas no consistent change was observed in MDMs. Productively infected CD4+ T cells express higher amount of p21 compared to bystander cells. In determining the mechanism(s) of cell type specific regulation of p21, we found that the miRNAs miR-106b and miR-20a that target p21 were specifically downregulated in HIV-1 infected CD4+ T cells. Overexpression of these two miRNAs reduced p21 expression significantly in HIV-1 infected CD4+ T cells. These findings provide a potential mechanism, by which, HIV-1 could exploit host cellular machineries to regulate selective gene expression in target cells. J. Cell. Biochem. 117: 1902-1912, 2016. © 2016 Wiley Periodicals, Inc.

Pilocarpine-induced seizures trigger differential regulation of microRNA-stability related genes in rat hippocampal neurons.

Epileptogenesis in the temporal lobe elicits regulation of gene expression and protein translation, leading to reorganization of neuronal networks. In this process, miRNAs were described as being regulated in a cell-specific manner, although mechanistics of miRNAs activity are poorly understood. The specificity of miRNAs on their target genes depends on their intracellular concentration, reflecting the balance of biosynthesis and degradation. Herein, we confirmed that pilocarpine application promptly (<30 min) induces status epilepticus (SE) as revealed by changes in rat electrocorticogram particularly in fast-beta range (21–30 Hz). SE simultaneously upregulated XRN2 and downregulated PAPD4 gene expression in the hippocampus, two genes related to miRNA degradation and stability, respectively. Moreover, SE decreased the number of XRN2-positive cells in the hilus, while reduced the number of PAPD4-positive cells in CA1. XRN2 and PAPD4 levels did not change in calretinin- and CamKII-positive cells, although it was possible to determine that PAPD4, but not XRN2, was upregulated in parvalbumin-positive cells, revealing that SE induction unbalances the accumulation of these functional-opposed proteins in inhibitory interneurons that directly innervate distinct domains of pyramidal cells. Therefore, we were able to disclose a possible mechanism underlying the differential regulation of miRNAs in specific neurons during epileptogenesis.

Ultrasound Stimulation of Different Dental Stem Cell Populations: Role of Mitogen-activated Protein Kinase Signaling

IntroductionMesenchymal stem cells (MSCs) from dental tissues may respond to low-intensity pulsed ultrasound (LIPUS) treatment, potentially providing a therapeutic approach to promoting dental tissue regeneration. This work aimed to compare LIPUS effects on the proliferation and MAPK signaling in MSCs from rodent dental pulp stem cells (DPSCs) compared with MSCs from periodontal ligament stem cells (PDLSCs) and bone marrow stem cells (BMSCs). MethodsIsolated MSCs were treated with 1-MHz LIPUS at an intensity of 250 or 750 mW/cm2 for 5 or 20 minutes. Cell proliferation was evaluated by 5-bromo-2-deoxyuridine (BrdU) staining after 24 hours of culture following a single LIPUS treatment. Specific ELISAs were used to determine the total and activated p38, ERK1/2, and JNK MAPK signaling proteins up to 4 hours after treatment. Selective MAPK inhibitors PD98059 (ERK1/2), SB203580 (p38), and SP600125 (JNK) were used to determine the role of activation of the particular MAPK pathways. ResultsThe proliferation of all MSC types was significantly increased after LIPUS treatment. LIPUS at a 750-mW/cm2 dose induced the greatest effects on DPSCs. BMSC proliferation was stimulated in equal measures by both intensities, whereas 250 mW/cm2 LIPUS exposure exerted maximum effects on PDLSCs. ERK1/2 was activated immediately in DPSCs after treatment. Concomitantly, DPSC proliferation was specifically modulated by ERK1/2 inhibition, whereas p38 and JNK inhibition exerted no effects. In BMSCs, JNK MAPK signaling was LIPUS activated, and the increase in proliferation was blocked by specific inhibition of the JNK pathway. In PDLSCs, JNK MAPK signaling was activated immediately after LIPUS, whereas p-p38 MAPK increased significantly in these cells 4 hours after exposure. Correspondingly, JNK and p38 inhibition modulated LIPUS-stimulated PDLSC proliferation. ConclusionsLIPUS promoted MSC proliferation in an intensity and cell-specific dependent manner via activation of distinct MAPK pathways.

A Viral mRNA Motif at the 3'-Untranslated Region that Confers Translatability in a Cell-Specific Manner. Implications for Virus Evolution.

Sindbis virus (SINV) mRNAs contain several motifs that participate in the regulation of their translation. We have discovered a motif at the 3′ untranslated region (UTR) of viral mRNAs, constituted by three repeated sequences, which is involved in the translation of both SINV genomic and subgenomic mRNAs in insect, but not in mammalian cells. These data illustrate for the first time that an element present at the 3′-UTR confers translatability to mRNAs from an animal virus in a cell-specific manner. Sequences located at the beginning of the 5′-UTR may also regulate SINV subgenomic mRNA translation in both cell lines in a context of infection. Moreover, a replicon derived from Sleeping disease virus, an alphavirus that have no known arthropod vector for transmission, is much more efficient in insect cells when the repeated sequences from SINV are inserted at its 3′-UTR, due to the enhanced translatability of its mRNAs. Thus, these findings provide a clue to understand, at the molecular level, the evolution of alphaviruses and their host range.

Genetic Tools to Study T Cell Development.

Genetics tools, and especially the ability to enforce, by transgenesis, or disrupt, by homologous recombination, gene expression in a cell-specific manner, have revolutionized the study of immunology and propelled the laboratory mouse as the main model to study immune responses. Perhaps more than any other aspect of immunology, the study of T cell development has benefited from these technologies. This brief chapter summarizes genetic tools specific to T cell development studies, focusing on mouse strains with lineage- and stage-specific expression of the Cre recombinase, or expressing unique antigen receptor specificities. It ends with a broader discussion of strategies to enforce ectopic lineage and stage-specific gene expression.

Role of microRNAs in spermatogenesis

Male germ cells have a complex transcriptome. In addition to proteincoding messenger RNAs, many noncoding RNAs, including microRNAs (miRNAs), are produced. The miRNAs are important regulators of gene expression. They function mainly post-transcriptionally to control the stability or translation of their target messenger RNAs. The miRNAs are expressed in a cell-specific manner during spermatogenesis to participate in the control of each stage of male germ cell differentiation. Clinical studies have exploited the well-defined expression profiles of miRNAs, and human spermatozoal or seminal plasma miRNAs have been explored as potential biomarkers for male factor infertility.

Titanates and Titanate-Metal Compounds in Biological Contexts.

Metal ions are notorious environmental contaminants, some causing toxicity at exquisitely low (ppm-level) concentrations. Yet, the redox properties of metal ions make them attractive candidates for bio-therapeutics. Titanates are insoluble particulate compounds of titanium and oxygen with crystalline surfaces that bind metal ions; these compounds offer a means to scavenge metal ions in environmental contexts or deliver them in therapeutic contexts while limiting systemic exposure and toxicity. In either application, the toxicological properties of titanates are crucial. To date, the accurate measurement of the in vitro toxicity of titanates has been complicated by their particulate nature, which interferes with many assays that are optical density (OD)-dependent, and at present, little to no in vivo titanate toxicity data exist. Compatibility data garnered thus far for native titanates in vitro are inconsistent and lacking in mechanistic understanding. These data suggest that native titanates have little toxicity toward several oral and skin bacteria species, but do suppress mammalian cell metabolism in a cells-pecific manner. Titanate compounds bind several types of metal ions, including some common environmental toxins, and enhance delivery to bacteria or cells. Substantial work remains to address the practical applicability of titanates. Nevertheless, titanates have promise to serve as novel vehicles for metal-based therapeutics or as a new class of metal scavengers for environmental applications.

Correlated confocal and super-resolution imaging by VividSTORM.

Single-molecule localization microscopy (SMLM) is rapidly gaining popularity in the life sciences as an efficient approach to visualize molecular distribution with nanoscale precision. However, it has been challenging to obtain and analyze such data within a cellular context in tissue preparations. Here we describe a 5-d tissue processing and immunostaining procedure that is optimized for SMLM, and we provide example applications to fixed mouse brain, heart and kidney tissues. We then describe how to perform correlated confocal and 3D-superresolution imaging on these sections, which allows the visualization of nanoscale protein localization within labeled subcellular compartments of identified target cells in a few minutes. Finally, we describe the use of VividSTORM (http://katonalab.hu/index.php/vividstorm), an open-source software for correlated confocal and SMLM image analysis, which facilitates the measurement of molecular abundance, clustering, internalization, surface density and intermolecular distances in a cell-specific and subcellular compartment-restricted manner. The protocol requires only basic skills in tissue staining and microscopy.

Proximal tubule-targeted heme oxygenase-1 in cisplatin-induced acute kidney injury.

Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that catalyzes the breakdown of heme to biliverdin, carbon monoxide, and iron. The beneficial effects of HO-1 expression are not merely due to degradation of the pro-oxidant heme but are also credited to the by-products that have potent, protective effects, including antioxidant, anti-inflammatory, and prosurvival properties. This is well reflected in the preclinical animal models of injury in both renal and nonrenal settings. However, excessive accumulation of the by-products can be deleterious and lead to mitochondrial toxicity and oxidative stress. Therefore, use of the HO system in alleviating injury merits a targeted approach. Based on the higher susceptibility of the proximal tubule segment of the nephron to injury, we generated transgenic mice using cre-lox technology to enable manipulation of HO-1 (deletion or overexpression) in a cell-specific manner. We demonstrate the validity and feasibility of these mice by breeding them with proximal tubule-specific Cre transgenic mice. Similar to previous reports using chemical modulators and global transgenic mice, we demonstrate that whereas deletion of HO-1, specifically in the proximal tubules, aggravates structural and functional damage during cisplatin nephrotoxicity, selective overexpression of HO-1 in proximal tubules is protective. At the cellular level, cleaved caspase-3 expression, a marker of apoptosis, and p38 signaling were modulated by HO-1. Use of these transgenic mice will aid in the evaluation of the effects of cell-specific HO-1 expression in response to injury and assist in the generation of targeted approaches that will enhance recovery with reduced, unwarranted adverse effects.

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner.

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the Nucleoskeleton and Cytoskeleton (LINC complexes). These protein scaffolds span the nuclear envelope and connect the interior of the nucleus to components of the surrounding cytoplasmic cytoskeleton. LINC complexes consist of two evolutionary-conserved protein families, Sun proteins and Nesprins that harbor C-terminal molecular signature motifs called the SUN and KASH domains, respectively. Sun proteins are transmembrane proteins of the inner nuclear membrane whose N-terminal nucleoplasmic domain interacts with the nuclear lamina while their C-terminal SUN domains protrudes into the perinuclear space and interacts with the KASH domain of Nesprins. Canonical Nesprin isoforms have a variable sized N-terminus that projects into the cytoplasm and interacts with components of the cytoskeleton. This protocol describes the validation of a dominant-negative transgenic mouse strategy that disrupts endogenous SUN/KASH interactions in a cell-type specific manner. Our approach is based on the Cre/Lox system that bypasses many drawbacks such as perinatal lethality and cell nonautonomous phenotypes that are associated with germline models of LINC complex inactivation. For this reason, this model provides a useful tool to understand the role of LINC complexes during development and homeostasis in a wide array of tissues.

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Quantifying the ‘escapers’ among RNA species

tRNAs are fundamental components of translation and emerging evidence places them more centrally in various other cellular processes. However, rather than being uniformly conserved, tRNA abundance is instead highly variable and adaptable. The amount of tRNA genes greatly differs among species. Moreover, even within the same genome, tRNA abundance shapes the proteome in a tissue- and cell-specific manner and is dynamically regulated in response to stress. Here, we review approaches for identification and quantification of tRNAs and their functional integrity. We discuss the resolution of each method and highlight new approaches with cell-wide resolution based on deep-sequencing technologies.

Mineralocorticoid receptor mediated liposomal delivery system for targeted induction of apoptosis in cancer cells

Mineralocorticoid receptors (MRs) are nuclear hormone receptors that are ubiquitously present in all cell types and are known to mediate distinct physiological functions like regulating Na+ and K+ balance and water excretion. MRs are linked to cell proliferation and can be exploited for the targeted control of cell mass in cancer. The present study is aimed towards extending the concept of using MR ligand spironolactone for selective delivery of genes in cancer cells. The lipoplex (SP) has shown MR mediated targeted transfections as indicated by receptor down-regulation studies using MR antagonists and siRNA. SP-targeted delivery of genes resulted in apoptosis in cell-specific manner while free drug was found to be cytotoxic irrespective of the cancerous or non-cancerous nature. In conclusion, this study presents MR as a target for efficiently delivering anticancer genes and thereby treating cancer through MR-mediated pathway.

The emerging role of coagulation proteases in kidney disease.

A role of coagulation proteases in kidney disease beyond their function in normal haemostasis and thrombosis has long been suspected, and studies performed in the past 15 years have provided novel insights into the mechanisms involved. The expression of protease-activated receptors (PARs) in renal cells provides a molecular link between coagulation proteases and renal cell function and revitalizes research evaluating the role of haemostasis regulators in renal disease. Renal cell-specific expression and activity of coagulation proteases, their regulators and their receptors are dynamically altered during disease processes. Furthermore, renal inflammation and tissue remodelling are not only associated, but are causally linked with altered coagulation activation and protease-dependent signalling. Intriguingly, coagulation proteases signal through more than one receptor or induce formation of receptor complexes in a cell-specific manner, emphasizing context specificity. Understanding these cell-specific signalosomes and their regulation in kidney disease is crucial to unravelling the pathophysiological relevance of coagulation regulators in renal disease. In addition, the clinical availability of small molecule targeted anticoagulants as well as the development of PAR antagonists increases the need for in-depth knowledge of the mechanisms through which coagulation proteases might regulate renal physiology.

MicroRNA-155 regulates tumor myeloid-derived suppressive cells.

MicroRNA is small non-coding RNA and can lead to translational repression or target degradation by base-pairing with complementary sequences of mRNA molecules. MicroRNA-155 (miR-155), one of the most studied microRNA, is the first one to be reported as oncogenic [1]. miR-155 is over expressed in a long list of both hematological and solid tumors and is of paramount importance in cancer diagnosis and prognosis. However, how miR-155 particularly in host immune system regulates the tumor progression remains poorly understood. Our study underscores a contextual role of miR-155 in regulating tumor growth and tumor immunity via distinct immune subsets within tumors [2]. We conclude that the balance of different effects between those immune cell populations, which are regulated by miR-155, appears to determine whether miR-155 promotes or inhibits tumor growth [2]. We demonstrated that host miR-155 deficiency promoted antitumor T cell immunity in multiple transplanted tumor models. Further analysis of immune cell compartments revealed that miR-155 was required for the accumulation and suppressive function of myeloid-derived suppressive cells (MDSC) in the tumor microenvironment. Apart from the direct modulation on MDSC, miR-155 was also required for the MDSC-mediated CD4+Foxp3+ regulatory T cells (Treg) induction. On the other hand, miR-155 deficiency hampered the antitumor responses of both dendritic cells and T cells. Therefore, it appears that in our tumor models, miR-155 mediated a dominant immunosuppressive effect by MDSC, leading to the enhanced overall antitumor immunity in miR-155 deficient hosts. Reduced colon inflammation and decreased colorectal carcinogenesis were also found in miR-155 deficient mice when azoxymethane (AOM) and dextran sodium sulphate (DSS) were combined to induce colon lesions. Furthermore, miR-155 was upregulated in MDSC either from tumor-bearing hosts or generated from bone marrow progenitors by GM-CSF and IL-6. These results support the notion that miR-155 is a prototypical microRNA bridging inflammation and cancer development [3]. Although miR-155 may regulate tumor growth in an intrinsic manner, it is likely that inflammation promotes the accumulation of functional MDSC by increased miR-155 that dampens the immune surveillance and antitumor immunity, thereby facilitating tumor growth. To identify the molecular mechanisms by which miR-155 regulates MDSC (Figure ​(Figure1),1), we found that miR155 retained the suppressive activity of MDSCs through inhibiting SOCS1. Moreover, inverse correlations between miR-155 expression and SHIP-1/SOCS1 expression were established in MDSC. As SHIP-1 was recently reported as a target of miR155 specifically in MDSC expansion [4], these results suggest both SHIP-1 and SOCS1 as target genes of miR-155 during functional MDSC generation. SOCS1 also restricted arginase I activity [5], which otherwise would limit the efficiency of MDSC proinflammatory responses. Indeed, we showed that miR-155−/− MDSC has a lower level of arginase activity than WT counterparts, and inhibition of arginase-I with specific inhibitors completely abrogated the suppressive activity of WT MDSC and did not affect the miR-155−/− MDSC. Our data indicate that miR-155 may modulate arginase-dependent suppressive function of MDSC via targeting SOCS1. Figure 1 miR-155 regulates tumor MDSC More interestingly, we observed the decreased production of MMP-9 and VEGF from miR-155−/− MDSC, which would presumably limit the tumor angiogenesis. Given a contribution of miR-155 expression by cancer cells to tumor angiogenesis [6], further studies will determine whether miR-155 regulates tumor angiogenesis through both cancer cells and MDSC within tumors. It is notable that our results on host miR155 deficiency and tumor growth differ from other recent studies [7, 8]. Differences in the tumor cell lines used that could change the accumulation of individual immune cell subsets in the tumor microenvironment may explain this discrepancy. The extent and modulation of major immune populations could vary in different tumor types and/or tumor stages. Thus, increased miR-155 could be a key player in balancing anti-and pro-tumor immune components within the tumor. In our given tumor model system, we provide clear evidence that miR-155 promotes tumor growth in an MDSC-dependent manner, as manifested via both “depletion” and “transfer” strategy in vivo. Taken together, our study highlights the essence of evaluating the intrinsic role of miR-155 carefully in distinct immune cell subsets, where miR-155 could be either protective or deleterious to antitumor immunity. In this regard, it would be safe and important to develop the anti-miR-155 cancer therapy in cell-specific manner. It is becoming evident that miR-155 functions as “OncomiR” in concert with “ImmunomiR” in orchestrating cancer growth and progression.

CuO nanoparticles induce cytotoxicity and apoptosis in human K562 cancer cell line via mitochondrial pathway, through reactive oxygen species and P53.

This study focused on determining cytotoxic effects of copper oxide nanoparticles (CuO NPs) on chronic myeloid leukemia (CML) K562 cell line in a cell-specific manner and its possible mechanism of cell death. We investigated the cytotoxicity of CuO NPs against K562 cell line (cancerous cell) and peripheral blood mononuclear cell (normal cell). The toxicity was evaluated using cell viability, oxidative stress and apoptosis detection. In addition, the expression levels of P53, Caspase 3, Bcl-2, and Bax genes in K562 cells were studied by reverse transcription polymerase chain reaction (RT-PCR) analysis. CuO NPs exerted distinct effects on cell viability via selective killing of cancer cells in a dose-dependent manner while not impacting normal cells in MTT assay. The dose-dependent cytotoxicity of CuO NPs against K562 cells was shown through reactive oxygen species (ROS) generation. The CuO NPs induced apoptosis was confirmed through acridine orange and propidium iodide double staining. Tumor suppressor gene P53 was up regulated due to CuO NPs exposure, and increase in Bax/Bcl-2 ratio suggested mitochondria-mediated pathway is involved in CuO NPs induced apoptosis. We also observed that Caspase 3 gene expression remained unchanged up to 24 hr exposure. These molecular alterations provide an insight into CuO NPs-caused inhibition of growth, generation of ROS, and apoptotic death of K562 cells.

Zinc affects miR-548n, SMAD4, SMAD5 expression in HepG2 hepatocyte and HEp-2 lung cell lines.

MicroRNAs affect disease progression and nutrient status. miR-548n increased 57 % in Zn supplemented plasma from adolescent females (ages 9 to 13 years). The purpose of this study was to determine the effects of Zn concentration in cell culture on the expression of miR-548n, SMAD4 and SMAD5 in hepatocyte (HepG2) and lung epithelium (HEp-2) cell lines. Cells were incubated for 48 h in media containing 10 % Chelex 100-treated FBS (0 μM Zn), or with 15 or 50 μM Zn, before isolation of total RNA and cDNA. Expression of miR-548n, SMAD4 and SMAD5 was measured by qPCR. The ΔΔCT method was used to calculate the fold-change, and 15 µM expression levels were used as reference values. HepG2 miR-548n expression decreased 5-fold, and SMAD4 expression increased 4-fold in the absence of Zn, while HEp-2 miR-548n expression increased 10.5-fold, and SMAD5 expression increased 20-fold in the absence of Zn. HEp-2 miR-548n expression increased 23-fold, while SMAD4 expression decreased twofold, in 50 μM Zn-treated cells. However, SMAD4 and SMAD5 expression was not correlated. These data indicate that miR-548n expression is in part regulated by Zn in a cell-specific manner. SMAD4 and SMAD5 are genes in the TGF-β/BMP signaling pathway, and SMAD5 is a putative target for miR-548n; Zn participates in regulating this pathway through controlling SMAD4 and SMAD5 expression. However, SMAD5 expression may be more sensitive to Zn than to miR-548n since SMAD5 expression was not inversely correlated with miR-548n expression.