Showing papers by "Carlo M. Croce published in 2007"

MicroRNA signatures in human cancers

Abstract: MicroRNA (miRNA) alterations are involved in the initiation and progression of human cancer. The causes of the widespread differential expression of miRNA genes in malignant compared with normal cells can be explained by the location of these genes in cancer-associated genomic regions, by epigenetic mechanisms and by alterations in the miRNA processing machinery. MiRNA-expression profiling of human tumours has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment. In addition, profiling has been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or that target protein- coding genes involved in cancer.

MicroRNA-133 controls cardiac hypertrophy

Abstract: Growing evidence indicates that microRNAs (miRNAs or miRs) are involved in basic cell functions and oncogenesis. Here we report that miR-133 has a critical role in determining cardiomyocyte hypertrophy. We observed decreased expression of both miR-133 and miR-1, which belong to the same transcriptional unit, in mouse and human models of cardiac hypertrophy. In vitro overexpression of miR-133 or miR-1 inhibited cardiac hypertrophy. In contrast, suppression of miR-133 by 'decoy' sequences induced hypertrophy, which was more pronounced than that after stimulation with conventional inducers of hypertrophy. In vivo inhibition of miR-133 by a single infusion of an antagomir caused marked and sustained cardiac hypertrophy. We identified specific targets of miR-133: RhoA, a GDP-GTP exchange protein regulating cardiac hypertrophy; Cdc42, a signal transduction kinase implicated in hypertrophy; and Nelf-A/WHSC2, a nuclear factor involved in cardiogenesis. Our data show that miR-133, and possibly miR-1, are key regulators of cardiac hypertrophy, suggesting their therapeutic application in heart disease.

MicroRNA-29 family reverts aberrant methylation in lung cancer by targeting DNA methyltransferases 3A and 3B.

Abstract: MicroRNAs (miRNAs) are small, noncoding RNAs that regulate expression of many genes. Recent studies suggest roles of miRNAs in carcinogenesis. We and others have shown that expression profiles of miRNAs are different in lung cancer vs. normal lung, although the significance of this aberrant expression is poorly understood. Among the reported down-regulated miRNAs in lung cancer, the miRNA (miR)-29 family (29a, 29b, and 29c) has intriguing complementarities to the 3′-UTRs of DNA methyltransferase (DNMT)3A and -3B (de novo methyltransferases), two key enzymes involved in DNA methylation, that are frequently up-regulated in lung cancer and associated with poor prognosis. We investigated whether miR-29s could target DNMT3A and -B and whether restoration of miR-29s could normalize aberrant patterns of methylation in non-small-cell lung cancer. Here we show that expression of miR-29s is inversely correlated to DNMT3A and -3B in lung cancer tissues, and that miR-29s directly target both DNMT3A and -3B. The enforced expression of miR-29s in lung cancer cell lines restores normal patterns of DNA methylation, induces reexpression of methylation-silenced tumor suppressor genes, such as FHIT and WWOX, and inhibits tumorigenicity in vitro and in vivo. These findings support a role of miR-29s in epigenetic normalization of NSCLC, providing a rationale for the development of miRNA-based strategies for the treatment of lung cancer.

Modulation of miR-155 and miR-125b Levels following Lipopolysaccharide/TNF-α Stimulation and Their Possible Roles in Regulating the Response to Endotoxin Shock

Abstract: 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.

MicroRNA expression patterns to differentiate pancreatic adenocarcinoma from normal pancreas and chronic pancreatitis.

Abstract: ContextWhile global microRNA (miRNA) expression patterns of many embryologic, physiologic, and oncogenic processes have been described, description of the role of miRNAs in ductal adenocarcinoma of the pancreas is lacking.ObjectiveTo define the expression pattern of miRNAs in pancreatic cancer and compare it with those of normal pancreas and chronic pancreatitis.Design and SettingSpecimens were obtained at a National Cancer Institute–designated comprehensive cancer center from patients with ductal adenocarcinoma of the pancreas (n = 65) or chronic pancreatitis (n = 42) (January 2000-December 2005). All patients underwent curative pancreatectomy; those with pancreatic cancer were chemotherapy-naive. RNA harvested from resected pancreatic cancers and matched benign adjacent pancreatic tissue as well as from chronic pancreatitis specimens was hybridized to miRNA microarrays.Main Outcome MeasuresIdentification of differentially expressed miRNAs that could differentiate pancreatic cancer from normal pancreas, chronic pancreatitis, or both, as well as a pattern of miRNA expression predictive of long-term (>24 months) survival. Significance of Analysis of Microarrays and Prediction of Analysis of Microarrays were undertaken to identify miRNAs predictive of tissue type and prognosis. P values were calculated by t test, adjusted for multiple testing. Kaplan-Meier survival curves were constructed using mean miRNA expression (high vs low) as threshold and compared by log-rank analysis.ResultsTwenty-one miRNAs with increased expression and 4 with decreased expression were identified that correctly differentiated pancreatic cancer from benign pancreatic tissue in 90% of samples by cross validation. Fifteen overexpressed and 8 underexpressed miRNAs differentiated pancreatic cancer from chronic pancreatitis with 93% accuracy. A subgroup of 6 miRNAs was able to distinguish long-term survivors with node-positive disease from those dying within 24 months. Finally, high expression of miR-196a-2 was found to predict poor survival (median, 14.3 months [95% confidence interval, 12.4-16.2] vs 26.5 months [95% confidence interval, 23.4-29.6]; P = .009).ConclusionsPancreatic cancer may have a distinct miRNA expression pattern that may differentiate it from normal pancreas and chronic pancreatitis. miRNA expression patterns may be able to distinguish between long- and short-term survivors, but these findings need to be validated in other study populations.

A MicroRNA Signature of Hypoxia

Abstract: Recent research has identified critical roles for microRNAs in a large number of cellular processes, including tumorigenic transformation. While significant progress has been made towards understanding the mechanisms of gene regulation by microRNAs, much less is known about factors affecting the expression of these noncoding transcripts. Here, we demonstrate for the first time a functional link between hypoxia, a well-documented tumor microenvironment factor, and microRNA expression. Microarray-based expression profiles revealed that a specific spectrum of microRNAs (including miR-23, -24, -26, -27, -103, -107, -181, -210, and -213) is induced in response to low oxygen, at least some via a hypoxia-inducible-factor-dependent mechanism. Select members of this group (miR-26, -107, and -210) decrease proapoptotic signaling in a hypoxic environment, suggesting an impact of these transcripts on tumor formation. Interestingly, the vast majority of hypoxia-induced microRNAs are also overexpressed in a variety of human tumors.

Interferon modulation of cellular microRNAs as an antiviral mechanism.

Abstract: Plants and invertebrates can use RNA silencing as a protective mechanism in viral infection. Now cellular microRNAs (miRNAs) have been found to have an antiviral function in mammalian cells too. Interferon-β is involved in the regulation of a number of cellular miRNAs in human cells, and eight of these are active against sequences on the hepatitis C virus. In addition, modulation of cellular miRNA levels are found to contribute significantly towards the antiviral effects of interferon-β, suggesting that they are a functioning component of the mammalian innate immune response. Plants and invertebrates can use RNA silencing as a protective mechanism in viral infection. Cellular microRNAs can have anti-viral activity also in mammalian cells, in this case by contributing to the antiviral effects of interferon beta against hepatitis C virus. RNA interference through non-coding microRNAs (miRNAs) represents a vital component of the innate antiviral immune response in plants and invertebrate animals; however, a role for cellular miRNAs in the defence against viral infection in mammalian organisms has thus far remained elusive1. Here we show that interferon beta (IFNβ) rapidly modulates the expression of numerous cellular miRNAs, and that eight of these IFNβ-induced miRNAs have sequence-predicted targets within the hepatitis C virus (HCV) genomic RNA. The introduction of synthetic miRNA-mimics corresponding to these IFNβ-induced miRNAs reproduces the antiviral effects of IFNβ on HCV replication and infection, whereas neutralization of these antiviral miRNAs with anti-miRNAs reduces the antiviral effects of IFNβ against HCV. In addition, we demonstrate that IFNβ treatment leads to a significant reduction in the expression of the liver-specific miR-122, an miRNA that has been previously shown to be essential for HCV replication2. Therefore, our findings strongly support the notion that mammalian organisms too, through the interferon system, use cellular miRNAs to combat viral infections.

Cyclin G1 Is a Target of miR-122a, a MicroRNA Frequently Down-regulated in Human Hepatocellular Carcinoma

Abstract: We investigated the role of microRNAs (miRNAs) in the pathogenesis of human hepatocellular carcinoma (HCC). A genome-wide miRNA microarray was used to identify differentially expressed miRNAs in HCCs arisen on cirrhotic livers. Thirty-five miRNAs were identified. Several of these miRNAs were previously found deregulated in other human cancers, such as members of the let-7 family, mir-221, and mir-145. In addition, the hepato-specific miR-122a was found down-regulated in approximately 70% of HCCs and in all HCC-derived cell lines. Microarray data for let-7a, mir-221, and mir-122a were validated by Northern blot and real-time PCR analysis. Understanding the contribution of deregulated miRNAs to cancer requires the identification of gene targets. Here, we show that miR-122a can modulate cyclin G1 expression in HCC-derived cell lines and an inverse correlation between miR-122a and cyclin G1 expression exists in primary liver carcinomas. These results indicate that cyclin G1 is a target of miR-122a and expand our knowledge of the molecular alterations involved in HCC pathogenesis and of the role of miRNAs in human cancer.

Micro-RNA profiling in kidney and bladder cancers

Abstract: Objectives Micro-RNAs are a group of small noncoding RNAs with modulator activity of gene expression Recently, micro-RNA genes were found abnormally expressed in several types of cancers To study the role of the micro-RNAs in human kidney and bladder cancer, we analyzed the expression profile of 245 micro-RNAs in kidney and bladder primary tumors Methods and materials A total of 27 kidney specimens (20 carcinomas, 4 benign renal tumors, and 3 normal parenchyma) and 27 bladder specimens (25 urothelial carcinomas and 2 normal mucosa) were included in the study Total RNA was used for hybridization on an oligonucleotide microchip for micro-RNA profiling developed in our laboratories This microchip contains 368 probes in triplicate, corresponding to 245 human and mouse micro-RNA genes Results A set of 4 human micro-RNAs (miR-28, miR-185, miR-27, and let-7f-2) were found significantly up-regulated in renal cell carcinoma (P < 005) compared to normal kidney Human micro-RNAs miR-223, miR-26b, miR-221, miR-103-1, miR-185, miR-23b, miR-203, miR-17-5p, miR-23a, and miR-205 were significantly up-regulated in bladder cancers (P < 005) compared to normal bladder mucosa Of the kidney cancers studied, there was no differential micro-RNA expression across various stages, whereas with increasing tumor-nodes-metastasis staging in bladder cancer, miR-26b showed a moderate decreasing trend (P = 0082) Conclusions Our results show that different micro-RNAs are deregulated in kidney and bladder cancer, suggesting the involvement of these genes in the development and progression of these malignancies Further studies are needed to clarify the role of micro-RNAs in neoplastic transformation and to test the potential clinical usefulness of micro-RNAs microarrays as diagnostic and prognostic tool

MicroRNA fingerprints during human megakaryocytopoiesis

Abstract: Described herein is a method of decreasing expression of HOXA1 in a subject having a cancer and/or myeloproliferative disorder associated with overexpression of a HOXA1 gene product where an effective amount of at least one miR-10a gene product or an isolated variant or biologically-active fragment thereof is administered to the subject sufficient to decrease expression of the HOXA1 gene product in the subject.

MicroRNAs 17-5p–20a–106a control monocytopoiesis through AML1 targeting and M-CSF receptor upregulation

Abstract: We investigated the role of microRNAs (miRNA) 17-5p, 20a and 106a in monocytic differentiation and maturation. In unilineage monocytic culture generated by haematopoietic progenitor cells these miRNAs are downregulated, whereas the transcription factor acute myeloid leukaemia-1 (AML1; also known as Runt-related transcription factor 1, Runx1) is upregulated at protein but not mRNA level. As miRNAs 17-5p, 20a and 106a bind the AML1 mRNA 3'UTR, their decline may unblock AML1 translation. Accordingly, transfection with miRNA 17-5p-20a-106a suppresses AML1 protein expression, leading to M-CSF receptor (M-CSFR) downregulation, enhanced blast proliferation and inhibition of monocytic differentiation and maturation. Treatment with anti-miRNA 17-5p, 20a and 106a causes opposite effects. Knockdown of AML1 or M-CSFR by short interfering RNA (siRNA) mimics the action of the miRNA 17-5p-20a-106a, confirming that these miRNAs target AML1, which promotes M-CSFR transcription. In addition, AML1 binds the miRNA 17-5p-92 and 106a-92 cluster promoters and transcriptionally inhibits the expression of miRNA 17-5p-20a-106a. These studies indicate that monocytopoiesis is controlled by a circuitry involving sequentially miRNA 17-5p-20a-106a, AML1 and M-CSFR, whereby miRNA 17-5p-20a-106a function as a master gene complex interlinked with AML1 in a mutual negative feedback loop.

MicroRNAs (miR)-221 and miR-222, both overexpressed in human thyroid papillary carcinomas, regulate p27Kip1 protein levels and cell cycle.

Abstract: We have recently reported that MicroRNAs (miR)-221 and miR-222 were up-regulated in human thyroid papillary carcinomas in comparison with the normal thyroid tissue. Bioinformatic analysis proposed the p27(Kip1) protein, a key regulator of cell cycle, as a candidate target for the miR-221/222 cluster. Here, we report that the enforced expression of miR-221 and miR-222 was able to reduce p27(Kip1) protein levels in thyroid carcinoma and HeLa cells in the absence of significant changes in specific p27(Kip1) mRNA levels. This effect is direct as miR-221 and miR-222 negatively regulate the expression of the 3'-untranslated region-based reporter construct from the p27(Kip1) gene, and is dependent on two target sites in this region. Consistent with these results, an enforced expression of the miR-221 and miR-222 induced the thyroid papillary carcinoma cell line (TPC-1) to progress to the S phase of the cell cycle. It is likely that the negative regulation of p27(Kip1) by miR-221 and miR-222 might also have a role in vivo since we report an inverse correlation between miR-221 and miR-222 up-regulation and down-regulation of the p27(Kip1) protein levels in human thyroid papillary carcinomas. Therefore, the data reported here demonstrate that miR-221 and miR-222 are endogenous regulators of p27(Kip1) protein expression, and thereby, the cell cycle.

Specific microRNAs are downregulated in human thyroid anaplastic carcinomas.

Abstract: Thyroid carcinomas comprise a broad spectrum of tumors with different clinical behaviors. On the one side, there are occult papillary carcinomas (PTC), slow growing and clinically silent, and on the other side, rapidly growing anaplastic carcinomas (ATC), which are among the most lethal human neoplasms. We have analysed the microRNA (miR) profile of ATC in comparison to the normal thyroid using a microarray (miRNACHIP microarray). By this approach, we found an aberrant miR expression profile that clearly differentiates ATC from normal thyroid tissues and from PTC analysed in previous studies. In particular, a significant decrease in miR-30d, miR-125b, miR-26a and miR-30a-5p was detected in ATC in comparison to normal thyroid tissue. These results were further confirmed by northern blots, quantitative reverse transcription-PCR analyses and in situ hybridization. The overexpression of these four miRs in two human ATC-derived cell lines suggests a critical role of miR-125b and miR-26a downregulation in thyroid carcinogenesis, since a cell growth inhibition was achieved. Conversely, no effect on cell growth was observed after the overexpression of miR-30d and miR-30a-5p in the same cells. In conclusion, these data indicate a miR signature associated with ATC and suggest the miR deregulation as an important event in thyroid cell transformation.

Knockdown of ALR (MLL2) Reveals ALR Target Genes and Leads to Alterations in Cell Adhesion and Growth

Abstract: ALR (MLL2) is a member of the human MLL family, which belongs to a larger SET1 family of histone methyltransferases. We found that ALR is present within a stable multiprotein complex containing a cohort of proteins shared with other SET1 family complexes and several unique components, such as PTIP and the jumonji family member UTX. Like other complexes formed by SET1 family members, the ALR complex exhibited strong H3K4 methyltransferase activity, conferred by the ALR SET domain. By generating ALR knockdown cell lines and comparing their expression profiles to that of control cells, we identified a set of genes whose expression is activated by ALR. Some of these genes were identified by chromatin immunoprecipitation as direct ALR targets. The ALR complex was found to associate in an ALR-dependent fashion with promoters and transcription initiation sites of target genes and to induce H3K4 trimethylation. The most characteristic features of the ALR knockdown cells were changes in the dynamics and mode of cell spreading/polarization, reduced migration capacity, impaired anchorage-dependent and -independent growth, and decreased tumorigenicity in mice. Taken together, our results suggest that ALR is a transcriptional activator that induces the transcription of target genes by covalent histone modification. ALR appears to be involved in the regulation of adhesion-related cytoskeletal events, which might affect cell growth and survival.

MicroRNA gene expression during retinoic acid-induced differentiation of human acute promyelocytic leukemia

Abstract: MicroRNAs (miRNAs) are small non-coding RNAs of 19-25 nucleotides that are involved in the regulation of critical cell processes such as apoptosis, cell proliferation and differentiation. However, little is known about the role of miRNAs in granulopoiesis. Here, we report the expression of miRNAs in acute promyelocytic leukemia patients and cell lines during all-trans-retinoic acid (ATRA) treatment by using a miRNA microarrays platform and quantitative real time-polymerase chain reaction (qRT-PCR). We found upregulation of miR-15a, miR-15b, miR-16-1, let-7a-3, let-7c, let-7d, miR-223, miR-342 and miR-107, whereas miR-181b was downregulated. Among the upregulated miRNAs, miR-107 is predicted to target NFI-A, a gene that has been involved in a regulatory loop involving miR-223 and C/EBPa during granulocytic differentiation. Indeed, we have confirmed that miR-107 targets NF1-A. To get insights about ATRA regulation of miRNAs, we searched for ATRA-modulated transcription factors binding sites in the upstream genomic region of the let-7a-3/let-7b cluster and identified several putative nuclear factor-kappa B (NF-kappaB) consensus elements. The use of reporter gene assays, chromatin immunoprecipitation and site-directed mutagenesis revealed that one proximal NF-kappaB binding site is essential for the transactivation of the let-7a-3/let-7b cluster. Finally, we show that ATRA downregulation of RAS and Bcl2 correlate with the activation of known miRNA regulators of those proteins, let-7a and miR-15a/miR-16-1, respectively.

mRNA/microRNA gene expression profile in microsatellite unstable colorectal cancer

Abstract: Colorectal cancer develops through two main genetic instability pathways characterized by distinct pathologic features and clinical outcome. We investigated colon cancer samples (23 characterized by microsatellite stability, MSS, and 16 by high microsatellite instability, MSI-H) for genome-wide expression of microRNA (miRNA) and mRNA. Based on combined miRNA and mRNA gene expression, a molecular signature consisting of twenty seven differentially expressed genes, inclusive of 8 miRNAs, could correctly distinguish MSI-H versus MSS colon cancer samples. Among the differentially expressed miRNAs, various members of the oncogenic miR-17-92 family were significantly up-regulated in MSS cancers. The majority of protein coding genes were also up-regulated in MSS cancers. Their functional classification revealed that they were most frequently associated with cell cycle, DNA replication, recombination, repair, gastrointestinal disease and immune response. This is the first report that indicates the existence of differences in miRNA expression between MSS versus MSI-H colorectal cancers. In addition, the work suggests that the combination of mRNA/miRNA expression signatures may represent a general approach for improving bio-molecular classification of human cancer.

MicroRNAs in human cancer: from research to therapy

Abstract: Numerous miRNAs are deregulated in human cancers, and experimental evidence indicates that they can play roles as oncogenes or tumor suppressor genes. Similarly to cancer genes that encode proteins, deregulation of miRNA-encoding genes is associated with genetic or epigenetic alterations, such as deletions, amplifications, point mutations and aberrant DNA methylation. The discovery that miRNAs interact with known oncogenes has established further links with molecular pathways implicated in malignant transformation. Finally, miRNAs can be used as diagnostic markers, and their potential as therapeutic molecules has moved miRNAs from the area of basic research to the field of cancer biotechnology.

MicroRNA expression profiles for the NCI-60 cancer cell panel

Abstract: Advances in the understanding of cancer cell biology and response to drug treatment have benefited from new molecular technologies and methods for integrating information from multiple sources. The NCI-60, a panel of 60 diverse human cancer cell lines, has been used by the National Cancer Institute to screen >100,000 chemical compounds and natural product extracts for anticancer activity. The NCI-60 has also been profiled for mRNA and protein expression, mutational status, chromosomal aberrations, and DNA copy number, generating an unparalleled public resource for integrated chemogenomic studies. Recently, microRNAs have been shown to target particular sets of mRNAs, thereby preventing translation or accelerating mRNA turnover. To complement the existing NCI-60 data sets, we have measured expression levels of microRNAs in the NCI-60 and incorporated the resulting data into the CellMiner program package for integrative analysis. Cell line groupings based on microRNA expression were generally consistent with tissue type and with cell line clustering based on mRNA expression. However, mRNA expression seemed to be somewhat more informative for discriminating among tissue types than was microRNA expression. In addition, we found that there does not seem to be a significant correlation between microRNA expression patterns and those of known target transcripts. Comparison of microRNA expression patterns and compound potency patterns showed significant correlations, suggesting that microRNAs may play a role in chemoresistance. Combined with gene expression and other biological data using multivariate analysis, microRNA expression profiles may provide a critical link for understanding mechanisms involved in chemosensitivity and chemoresistance.

Targeted deletion of Wwox reveals a tumor suppressor function.

Abstract: The WW domain-containing oxidoreductase (WWOX) spans the second most common fragile site of the human genome, FRA16D, located at 16q23, and its expression is altered in several types of human cancer. We have previously shown that restoration of WWOX expression in cancer cells suppresses tumorigenicity. To investigate WWOX tumor suppressor function in vivo, we generated mice carrying a targeted deletion of the Wwox gene and monitored incidence of tumor formation. Osteosarcomas in juvenile Wwox−/− and lung papillary carcinoma in adult Wwox+/− mice occurred spontaneously. In addition, Wwox+/− mice develop significantly more ethyl nitrosourea-induced lung tumors and lymphomas in comparison to wild-type littermate mice. Intriguingly, these tumors still express Wwox protein, suggesting haploinsuffiency of WWOX itself is cancer predisposing. These results indicate that WWOX is a bona fide tumor suppressor.

Identification of differentially expressed microRNAs by microarray: a possible role for microRNA genes in pituitary adenomas.

Abstract: MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by targeting mRNA. It has been demonstrated that miRNA expression is altered in many human cancers, suggesting that they may play a role in human neoplasia. To determine whether miRNA expression is altered in pituitary adenomas, we analyzed the entire miRNAome in 32 pituitary adenomas and in 6 normal pituitary samples by microarray and by Real-Time PCR. Here, we show that 30 miRNAs are differentially expressed between normal pituitary and pituitary adenomas. Moreover, 24 miRNAs were identified as a predictive signature of pituitary adenoma and 29 miRNAs were able to predict pituitary adenoma histotype. miRNA expression could differentiate micro- from macro-adenomas and treated from non-treated patient samples. Several of the identified miRNAs are involved in cell proliferation and apoptosis, suggesting that their deregulated expression may be involved in pituitary tumorigenesis. Predictive miRNAs could be potentially useful diagnostic markers, improving the classification of pituitary adenomas.

Chromosomal rearrangements and microRNAs: a new cancer link with clinical implications.

Abstract: There is widespread aberrant expression of mature and/or precursor microRNAs in cancer cells, as microRNAs are deregulated consequent to chromosomal alterations and other genomic abnormalities. The identification of such abnormalities has a clear diagnostic and prognostic significance, and there are ever increasing examples of links between certain human cancers and modifications at microRNA loci.

Microrna expression abnormalities in pancreatic endocrine and acinar tumors

Abstract: The present invention relates to a method of diagnosing whether a subject has, or is at risk for developing, pancreatic cancer, comprising measuring the level of at least one miR gene product in a test sample from said subject, wherein an increase in the level of the miR gene product in the test sample, relative to the level of a corresponding miR gene product in a control sample, is indicative of the subject either having, or being at risk for developing, pancreatic cancer, wherein the type of pancreatic cancer is a pancreatic endocrine tumor (PET), and the at least one miR gene product is selected from the group consisting of: miR-103, miR-107, miR-125a, miR-99a, miR-99b, miR-125b-1, miR-342, miR-130a, miR-100, miR-132, miR-129-2, miR-125b-2 and a combination thereof. The invention also relates to a probe for hybridization comprising a miRNA selected from the above group.

MicroRNA genes are frequently located near mouse cancer susceptibility loci

Abstract: MicroRNAs (miRNAs) are short 19- to 24-nt RNA molecules that have been shown to regulate the expression of other genes in a variety of eukaryotic systems. Abnormal expression of miRNAs has been observed in several human cancers, and furthermore, germ-line and somatic mutations in human miRNAs were recently identified in patients with chronic lymphocytic leukemia. Thus, human miRNAs can act as tumor suppressor genes or oncogenes, where mutations, deletions, or amplifications can underlie the development of certain types of leukemia. In addition, previous studies have shown that miRNA expression profiles can distinguish among human solid tumors from different organs. Because a single miRNA can simultaneously influence the expression of two or more protein-coding genes, we hypothesized that miRNAs could be candidate genes for cancer risk. Research in complex trait genetics has demonstrated that genetic background determines cancer susceptibility or resistance in various tissues, such as colon and lung, of different inbred mouse strains. We compared the genome positions of mouse tumor susceptibility loci with those of mouse miRNAs. Here, we report a statistically significant association between the chromosomal location of miRNAs and those of mouse cancer susceptibility loci that influence the development of solid tumors. Furthermore, we identified distinct patterns of flanking DNA sequences for several miRNAs located at or near susceptibility loci in inbred strains with different tumor susceptibilities. These data provide a catalog of miRNA genes in inbred strains that could represent genes involved in the development and penetrance of solid tumors.

Microrna-based methods and compositions for the diagnosis and treatment of solid cancers

Abstract: The present invention provides novel methods for the diagnosis of breast cancer. The methods comprise measuring the levels of at least one miR gene product selected from the group consisting of miR-125b-2, miR-125b-1, miR-10b, miR-181a, miR-140, miR-213, miR-29a prec, miR-199b, miR-29b-1, miR-130a, miR-155, let-7a-2, miR-29c, miR-224, miR-31, miR-122a, miR-16-2, miR-30c, miR-17-5p, miR-210, miR-29b-2, miR-146, miR-181b-1, and combinations thereof wherein an alteration in the level of the miR gene product in the test sample, relative to the level of the corresponding miR gene product in a control sample, is indicative of the subject having breast cancer. The methods also comprise measuring the levels of a group of miR gene products consisting of miR-125b-2, miR-125b-1, miR-10b, miR-181a, miR-140, miR-213, miR-29a prec, miR-199b, miR-29b-1, miR-130a, miR-155, let-7a-2, miR-29c, miR-224, miR-31, miR-122a, miR-16-2, miR-21, miR-145, miR-205, miR-100, miR-30c, miR-17-5p, miR-210, miR-29b-2, miR-146 and miR-181b-1.

Microrna-Based Methods and Compositions for the Diagnosis, Prognosis and Treatment of Lung Cancer

Abstract: The invention provides methods of diagnosing whether a subject has, or is at risk for developing, lung cancer, comprising measuring the level of at least one miR gene product in a test sample from said subject, wherein an alteration in the level of the miR gene products in the test sample, relative to the level of corresponding miR gene products in a control sample, is indicative of the subject either having, or being at risk for developing, lung cancer. The invention also provides methods of diagnosing whether a subject has, or is at risk for developing, lung cancer, comprising: reverse transcribing RNA from a test sample obtained from the subject to provide a set of target oligodeoxynucleotides; hybridizing the target oligodeoxynucleotides to a microarray comprising miRNA-specific probe oligonucleotides to provide a hybridization profile for the test sample; and comparing the test sample hybridization profile to a hybridization profile generated from a control sample, wherein an alteration in the signal of at least one miRNA is indicative of the subject either having, or being at risk for developing, lung cancer. The at least one miR gene product is selected from the group consisting of miR-21, miR-205 and miR-216.

WWOX in biological control and tumorigenesis.

Abstract: The WW domain-containing oxidoreductase (WWOX) gene is located at 16q23.1–16q23.2, a region that spans the second most common human fragile site, FRA16D. The WWOX protein contains two N-terminal WW domains and a central short chain oxidoreductase-like domain. In the last few years, considerable amount of data have shown inactivation of WWOX in a variety of human malignancies. Moreover, interacting partners have been identified biochemically that define, at least in part, the molecular mechanism of WWOX action. Recently, we demonstrated that targeted deletion of the Wwox gene in the mouse led to increased incidence of spontaneous and chemically induced tumor formation, thereby providing the first in vivo evidence that WWOX is a bona fide tumor suppressor. This review focuses on the most recent progress in understanding WWOX function as a tumor suppressor. J. Cell. Physiol. 212: 307–310, 2007. © 2007 Wiley-Liss, Inc.

Association of Wwox with ErbB4 in Breast Cancer

Abstract: WWOX, WW domain-containing oxidoreductase, is a tumor suppressor that is altered in many human cancers, including breast cancer. Wwox interacts with the ErbB4 receptor, reduces nuclear translocation of the cleaved intracellular domain of ErbB4, and inhibits its transactivation function mediated through Yes-associated protein. Here, we assessed the clinical significance of the Wwox-ErbB4 association. We determined Wwox protein expression by immunohistochemistry in a series of 556 breast cancers. Wwox expression was absent in 36% of the cancers, and loss of Wwox expression was associated with unfavorable outcome (P = 0.02). Membranous location of ErbB4 was associated with favorable survival compared with women whose cancer lacked such ErbB4 expression (P = 0.02). Wwox expression was strongly associated with membranous ErbB4 localization (P = 0.0003) and with overall ErbB4 expression (P = 0.0002). Coexpression of membranous ErbB4 and Wwox was associated with favorable outcome compared with cases with membranous ErbB4 and no Wwox immunoreactivity (P = 0.002). In vitro, Wwox associated with the two ErbB4 isoforms, JM-a CYT-1 and JM-a CYT-2, expressed in breast cancer. Moreover, expression of Wwox both in vitro and in vivo led to accumulation of total full-length membrane-associated ErbB4. These results suggest that expression of Wwox is associated with ErbB4 expression and that their coexpression has prognostic significance in breast cancer.

Oncogenic All1 fusion proteins target Drosha-mediated microRNA processing

Abstract: MicroRNAs (miRNAs) are noncoding small RNA of ≈22 bases, which suppress expression of target genes through translational block or degradation of a target's transcript. Recent studies uncovered specific miRNA expression profiles in human malignancies. Nevertheless, the mechanisms underlying cancer-specific miRNA expression are largely unknown. miRNA biogenesis consists of a series of steps beginning with generation of a primary transcript, termed pri-miRNA, and continuing into excision of a stem-loop hairpin structure within pri-miRNA by the nuclear RNaseIII enzyme Drosha, transportation to the cytoplasm, and further processing by a second RNaseIII enzyme Dicer, into a 22-base mature duplex RNA. In principle, alteration in any step during this maturation process could affect miRNA production. The ALL-1 (also termed MLL) gene was originally isolated by virtue of its involvement in recurrent chromosome translocations associated with acute leukemias, particularly in infant and therapy-related leukemias. These translocations result in the fusion of ALL-1 with partner genes and the consequent production of chimeric leukemogenic proteins. Here, we identify specific miRNAs up-regulated in leukemias triggered by All1 fusions. Further, we demonstrate coimmunoprecipitation of the All1/Af4 and All1/Af9 fusions with Drosha, disrupted by treatment with DNase I. Finally, we present evidence from ChIP experiments for All1 fusion protein-mediated recruitment of Drosha to target genes encoding miRNAs. Such recruitment may underlie the enhanced expression of the relevant miRNAs.