Association of a microRNA/TP53 feedback circuitry with pathogenesis and outcome of B-cell chronic lymphocytic leukemia

CONTEXT

Chromosomal abnormalities (namely 13q, 17p, and 11q deletions) have prognostic implications and are recurrent in chronic lymphocytic leukemia (CLL), suggesting that they are involved in a common pathogenetic pathway; however, the molecular mechanism through which chromosomal abnormalities affect the pathogenesis and outcome of CLL is unknown.

OBJECTIVE

To determine whether the microRNA miR-15a/miR-16-1 cluster (located at 13q), tumor protein p53 (TP53, located at 17p), and miR-34b/miR-34c cluster (located at 11q) are linked in a molecular pathway that explains the pathogenetic and prognostic implications (indolent vs aggressive form) of recurrent 13q, 17p, and 11q deletions in CLL.

DESIGN, SETTING, AND PATIENTS

CLL Research Consortium institutions provided blood samples from untreated patients (n = 206) diagnosed with B-cell CLL between January 2000 and April 2008. All samples were evaluated for the occurrence of cytogenetic abnormalities as well as the expression levels of the miR-15a/miR-16-1 cluster, miR-34b/miR-34c cluster, TP53, and zeta-chain (TCR)-associated protein kinase 70 kDa (ZAP70), a surrogate prognostic marker of CLL. The functional relationship between these genes was studied using in vitro gain- and loss-of-function experiments in cell lines and primary samples and was validated in a separate cohort of primary CLL samples.

MAIN OUTCOME MEASURES

Cytogenetic abnormalities; expression levels of the miR-15a/miR-16-1 cluster, miR-34 family, TP53 gene, downstream effectors cyclin-dependent kinase inhibitor 1A (p21, Cip1) (CDKN1A) and B-cell CLL/lymphoma 2 binding component 3 (BBC3), and ZAP70 gene; genetic interactions detected by chromatin immunoprecipitation.

RESULTS

In CLLs with 13q deletions the miR-15a/miR-16-1 cluster directly targeted TP53 (mean luciferase activity for miR-15a vs scrambled control, 0.68 relative light units (RLU) [95% confidence interval {CI}, 0.63-0.73]; P = .02; mean for miR-16 vs scrambled control, 0.62 RLU [95% CI, 0.59-0.65]; P = .02) and its downstream effectors. In leukemic cell lines and primary CLL cells, TP53 stimulated the transcription of miR-15/miR-16-1 as well as miR-34b/miR-34c clusters, and the miR-34b/miR-34c cluster directly targeted the ZAP70 kinase (mean luciferase activity for miR-34a vs scrambled control, 0.33 RLU [95% CI, 0.30-0.36]; P = .02; mean for miR-34b vs scrambled control, 0.31 RLU [95% CI, 0.30-0.32]; P = .01; and mean for miR-34c vs scrambled control, 0.35 RLU [95% CI, 0.33-0.37]; P = .02).

CONCLUSIONS

A microRNA/TP53 feedback circuitry is associated with CLL pathogenesis and outcome. This mechanism provides a novel pathogenetic model for the association of 13q deletions with the indolent form of CLL that involves microRNAs, TP53, and ZAP70.

Development of a minor groove binder assay for real-time one-step RT-PCR detection of swine vesicular disease virus

The design and development of a 5' conjugated minor groove binder (MGB) probe real-time RT-PCR assay are described for rapid, sensitive and specific detection of swine vesicular disease virus (SVDV) RNA. The assay is designed to target the 2C gene of the SVDV genome and is capable of detecting 2×10(2) copies of an RNA standard per reaction. It does not detect any of the other RNA viruses that cause vesicular disease in pigs, or the human enterovirus, Coxsackie B5 virus (CVB5) which is closely related antigenically to SVDV. The linear range of this test was from 2×10(2) to 2×10(8) copies/μl. The assay is rapid and can detect SVDV RNA in just over 3.5 h including the time required for nucleic acid extraction. The development of this assay provides a useful tool for the differential diagnosis of SVD or for the detection of SVDV in research applications. This study demonstrates the suitability of MGB probes as a real-time PCR chemistry for the diagnosis of swine vesicular disease.

Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD

An inflammatory component is present in the microenvironment of most neoplastic tissues, including those not causally related to an obvious inflammatory process. Several microRNAs, and especially miR-155, play an essential role in both the innate and adaptative immune response. Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural antioxidant with anti-inflammatory properties that is currently at the stage of preclinical studies for human cancer prevention. Here, we establish that, in human THP-1 monocytic cells as well as in human blood monocytes, resveratrol upregulates miR-663, a microRNA potentially targeting multiple genes implicated in the immune response. In THP-1 cells, miR-663 decreases endogenous activator protein-1 (AP-1) activity and impairs its upregulation by lipopolysaccharides (LPS), at least in part by directly targeting JunB and JunD transcripts. We further establish that the downregulation of AP-1 activity by resveratrol is miR-663 dependent and that the effects of resveratrol on both AP-1 activity and JunB levels are dose dependent. Finally, we show that resveratrol impairs the upregulation of miR-155 by LPS in a miR-663-dependent manner. Given the role of miR-155 in the innate immune response and the fact that it is upregulated in many cancers, our results suggest that manipulating miR-663 levels may help to optimize the use of resveratrol as both an anti-inflammatory and anticancer agent against malignancies associated with high levels of miR-155.

Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD

An inflammatory component is present in the microenvironment of most neoplastic tissues, including those not causally related to an obvious inflammatory process. Several microRNAs, and especially miR-155, play an essential role in both the innate and adaptative immune response. Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural antioxidant with anti-inflammatory properties that is currently at the stage of preclinical studies for human cancer prevention. Here, we establish that, in human THP-1 monocytic cells as well as in human blood monocytes, resveratrol upregulates miR-663, a microRNA potentially targeting multiple genes implicated in the immune response. In THP-1 cells, miR-663 decreases endogenous activator protein-1 (AP-1) activity and impairs its upregulation by lipopolysaccharides (LPS), at least in part by directly targeting JunB and JunD transcripts. We further establish that the downregulation of AP-1 activity by resveratrol is miR-663 dependent and that the effects of resveratrol on both AP-1 activity and JunB levels are dose dependent. Finally, we show that resveratrol impairs the upregulation of miR-155 by LPS in a miR-663-dependent manner. Given the role of miR-155 in the innate immune response and the fact that it is upregulated in many cancers, our results suggest that manipulating miR-663 levels may help to optimize the use of resveratrol as both an anti-inflammatory and anticancer agent against malignancies associated with high levels of miR-155.

An ets2-driven transcriptional program in tumor-associated macrophages promotes tumor metastasis

Tumor-associated macrophages (TAM) are implicated in breast cancer metastasis, but relatively little is known about the underlying genes and pathways that are involved. The transcription factor Ets2 is a direct target of signaling pathways involved in regulating macrophage functions during inflammation. We conditionally deleted Ets in TAMs to determine its function at this level on mouse mammary tumor growth and metastasis. Ets2 deletion in TAMs decreased the frequency and size of lung metastases in three different mouse models of breast cancer metastasis. Expression profiling and chromatin immunoprecipitation assays in isolated TAMs established that Ets2 repressed a gene program that included several well-characterized inhibitors of angiogenesis. Consistent with these results, Ets2 ablation in TAMs led to decreased angiogenesis and decreased growth of tumors. An Ets2-TAM expression signature consisting of 133 genes was identified within human breast cancer expression data which could retrospectively predict overall survival of patients with breast cancer in two independent data sets. In summary, we identified Ets2 as a central driver of a transcriptional program in TAMs that acts to promote lung metastasis of breast tumors.

Epigenetics, miRNAs, and human cancer: a new chapter in human gene regulation

Cancer is a genetic and epigenetic disease. MicroRNAs (miRNAs), a class of small noncoding RNAs, have been shown to be deregulated in many diseases including cancer. An intertwined connection between epigenetics and miRNAs has been supported by the recent identification of a specific subgroup of miRNAs called "epi-miRNAs" that can directly and indirectly modulate the activity of the epigenetic machinery. The complexity of this connection is enhanced by the epigenetic regulation of miRNA expression that generates a fine regulatory feedback loop. This review focuses on how epigenetics affects the miRNome and how the recently identified epi-miRNAs regulate the epigenome in human cancers, ultimately contributing to human carcinogenesis.

Modulation of miR-155 and miR-125b levels following lipopolysaccharide/TNF-alpha stimulation and their possible roles in regulating the response to endotoxin shock

We report here that miR-155 and miR-125b play a role in innate immune response. LPS stimulation of mouse Raw 264.7 macrophages resulted in the up-regulation of miR-155 and down-regulation of miR-125b levels. The same changes also occurred when C57BL/6 mice were i.p. injected with LPS. Furthermore, the levels of miR-155 and miR-125b in Raw 264.7 cells displayed oscillatory changes in response to TNF-alpha. These changes were impaired by pretreating the cells with the proteasome inhibitor MG-132, suggesting that these two microRNAs (miRNAs) may be at least transiently under the direct control of NF-kappaB transcriptional activity. We show that miR-155 most probably directly targets transcript coding for several proteins involved in LPS signaling such as the Fas-associated death domain protein (FADD), IkappaB kinase epsilon (IKKepsilon), and the receptor (TNFR superfamily)-interacting serine-threonine kinase 1 (Ripk1) while enhancing TNF-alpha translation. In contrast, miR-125b targets the 3'-untranslated region of TNF-alpha transcripts; therefore, its down-regulation in response to LPS may be required for proper TNF-alpha production. Finally, Emu-miR-155 transgenic mice produced higher levels of TNF-alpha when exposed to LPS and were hypersensitive to LPS/d-galactosamine-induced septic shock. Altogether, our data suggest that the LPS/TNF-alpha-dependent regulation of miR-155 and miR-125b may be implicated in the response to endotoxin shock, thus offering new targets for drug design.

Heparin and EDTA as anticoagulant differentially affect cytokine mRNA level of cultured porcine blood cells

Cytokine mRNA expression profiles serve to characterize immune cell activation in different test systems. Both, diluted whole blood and isolated PBMC are widely applied for these studies. Comprehensive data regarding the suitability of different anticoagulants for profiling cytokine expression are not available for the pig. Therefore the aim of this study was to compare the effect of two commonly used anticoagulants (heparin and EDTA) on the cytokine expression pattern of porcine blood cells. IL-1alpha, IL-2, IL-4, IL-6, IL-10 and IFN-gamma mRNA levels were detected ex-vivo and upon in-vitro stimulation in diluted porcine whole blood and isolated PBMC by real-time PCR. The cells were stimulated with ConA or LPS, known to act on different target cells and implying different signalling pathways. Additionally the integrity of the isolated RNA was investigated. Ex-vivo cytokine expression pattern of fresh whole blood were not affected by the investigated anticoagulants. In contrast, stimulation of cultured diluted whole blood or PBMC resulted in significant differences depending on the applied anticoagulant. Using EDTA we found a significantly decreased capacity of whole blood to express cytokines. However, isolated PBMC from EDTA anticoagulated blood showed a higher cytokine expression capacity than PBMC from heparinized blood. Comparing diluted whole blood and PBMC we found that cultured porcine whole blood responded better to bacterial products than isolated PBMC, probably because sufficient auxiliary plasma derived factors such as LPS-binding protein, are present. However, isolated PBMC showed a higher T-cell response than diluted whole blood. In conclusion, our findings underline that each application demands a specific assay system.

A fluorimeter-based RT-PCR method for the detection and quantitation of porcine cytokines

In this paper, we describe a fluorimeter-based, closed-tube, polymerase chain reaction (PCR) assay for the detection and quantification of the mRNA of porcine interleukin 1alpha (IL1alpha) and interleukin 2 (IL2) cytokines in peripheral blood leukocytes (PBLs) using melting curve analysis and compare it to a standard PCR performed in a block-based thermocycler.

Porcine rubulavirus LPMV RNA persists in the central nervous system of pigs after recovery from acute infection

In order to study persistence of the porcine rubulavirus LPMV, we examined tissue samples collected from pigs 53 days after experimental infection. These pigs survived the initial infection and could clinically be considered to have recovered from the infection. Two of the pigs used in this study were chemically immunosuppressed during the last 4 days before necropsy. No infectious virus or viral antigen could be detected in any tissue using standard methods for virus isolation and detection. However, the presence of viral genomic RNA and mRNA could be demonstrated in the mid brain of the convalescent pig using an optimised RT-nested PCR. Mid brain, forebrain and lung were all shown to contain LPMV RNA in the immunosuppressed convalescent pigs. In addition we examined the P-gene editing in the recovered pigs and conclude that the viral genome is transcriptionally active in these pigs. The relevance of the persistence of LPMV for maintenance and spread within and/or between pig populations is discussed.

Macrophages and respiratory viruses

This review highlights some of the interactions between alveolar macrophages and human/swine influenza A viruses, porcine reproductive and respiratory syndrome virus (PRRSV), bovine parainfluenza type-3 (PI-3) virus, bovine respiratory syncytial virus (BRSV) and bovine viral diarrhoea virus (BVDV). In influenza A infection, macrophage-cytokines are believed to mediate the typical constitutional effects and inflammation in the respiratory tract. The same cytokines possibly play a role in influenza-bacterial respiratory disease. PRRSV has a very restricted tropism for alveolar macrophages. The virus causes some secondary infections to be more severe, but this could not be related to impaired macrophage functions. Bovine RSV and PI-3 virus, on the other hand, interfere with selected macrophage functions. In addition, PI-3 virus adversely affects lymphocyte proliferation because it interferes with the accessory role of macrophages. One of the characteristic effects of BVDV on monocytes-macrophages is stimulation of prostaglandin E2 production.

A comparative study on the use of virus and antibody detection techniques for the diagnosis of La Piedad Michoacan paramyxovirus (LPMV) infection in pigs

La Piedad Michoacan paramyxovirus (LPMV) is newly recognized paramyxovirus that has been associated with neurologic and reproductive disorders in pigs in Mexico. To date, no comparative study of methods for the diagnosis of infection with this virus has been published. In this study, we identified tissues containing maximum virus load to optimize virus isolation procedures, and we compared this method to a rapid diagnostic test employing immunostaining of impression smears for LPMV antigens. In addition, several of the available tests for detecting LPMV antibodies were compared for their sensitivity in detecting seroconversion. Pigs used for the study of virus load in tissues and serologic studies were inoculated at 17 days of age with 10(7.00) TCID50 of LPMV. Serial blood samples were collected from selected pigs, and selected pigs were necropsied over a 14-day period. Pigs used in the investigation comparing standard virus isolation techniques to immunostaining of impression smears were inoculated at 3 days of age as described above and necropsied over an 8-day period. The results demonstrate that in the 17-day-old pigs maximum virus titers were detected in olfactory bulb at 5 days postinoculation (PI) and in midbrain at 9 days PI. In addition, the most consistent recovery of high titer virus was from tonsil (3-9 days PI) and olfactory bulb (4-9 days PI). Immunostaining of impression smears was as sensitive as virus isolation when selected tissues (lung, midbrain, olfactory bulb) were compared, with virus detected by both methods in 11/13 samples and in 1 sample each by immunostaining and virus isolation, respectively. All of the serology tests investigated detected seroconversion in pigs by 8 days PI. The identification of target organs where highest virus titers are found combined with immunofluorescent methods for the detection of LPMV antigens and a comparative study of the available serologic tests should facilitate the selection of techniques suitable for any laboratory to diagnose LPMV infection in pigs.

A sequential study of experimental porcine paramyxovirus (LPMV) infection of pigs: immunostaining of cryostat sections and virus isolation

La Piedad Michoacan Paramyxovirus (LPMV) is a recently recognized paramyxovirus infecting pigs throughout Mexico. Disease syndromes observed in field cases associated with LPMV infection include neurologic, respiratory, and reproductive disorders. Clinical signs and the distribution of LPMV virus and antigen in tissue samples from pigs experimentally infected with LPMV by natural routes were studied. Severe neurologic disease and death occurred following experimental inoculation of 3- and 17-day-old pigs. All of the pigs inoculated at 3 days of age were either dead or moribund by 8 days after inoculation, whereas 30% of the pigs inoculated at 17 days of age were affected. Virus was consistently recovered from or demonstrated in tissues from the respiratory tract of both groups of pigs. LPMV and antigen were also demonstrated in central nervous system (CNS) tissues from these pigs; however, differences in virus distribution within the CNS were demonstrated in the 2 groups. In the pigs inoculated at 17 days of age, isolation of LPMV was restricted to the olfactory bulb and midbrain. In contrast, in the pigs inoculated at 3 days of age, isolation of LPMV was more widespread throughout the CNS tissue examined. Virus excretion studies indicated that nasal spread of LPMV was more important than fecal spread. Comparatively large quantities of infectious LPMV were consistently recovered from urine samples of experimentally infected pigs.

Pathogenesis of porcine circovirus; experimental infections of colostrum deprived piglets and examination of pig foetal material

The results of virus and antigen distribution following experimental infection of colostrum deprived pigs with pig circovirus (PCV) by oral/nasal and intravenous routes are reported. PCV and antigen were detected using virus isolation and indirect immunofluorescence on cryostat sections respectively. PCV antigen was detected in tissues throughout the body but primarily in spleen thymus, and lung. No PCV antigen or virus was detected in tissue samples from the central nervous system. Examination of pig foetal material from field cases of abortion/stillbirth resulted in 3 PCV isolates from 2 sera and a spleen sample from 2 groups of stillborn piglets from the same farm. No antibody to PCV alone was detected in 160 foetal sera tested. These results suggest that transplacental infection with PCV does occur, possibly prior to foetal immunocompetance. However, it is probably not a significant cause of reproductive disorders in pigs in Northern Ireland.