The highly aggressive character of melanoma makes it an excellent model for probing the mechanisms underlying metastasis, which remains one of the most difficult challenges in treating cancer. We find that miR-182, member of a miRNA cluster in a chromosomal locus (7q31-34) frequently amplified in melanoma, is commonly upregulated in human melanoma cell lines and tissue samples; this up-regulation correlates with gene copy number in a subset of melanoma cell lines. Moreover, miR-182 ectopic expression stimulates migration of melanoma cells in vitro and their metastatic potential in vivo, whereas miR-182 down-regulation impedes invasion and triggers apoptosis. We further show that miR-182 over-expression promotes migration and survival by directly repressing microphthalmiaassociated transcription factor-M and FOXO3, whereas enhanced expression of either microphthalmia-associated transcription factor-M or FOXO3 blocks miR-182's proinvasive effects. In human tissues, expression of miR-182 increases with progression from primary to metastatic melanoma and inversely correlates with FOXO3 and microphthalmia-associated transcription factor levels. Our data provide a mechanism for invasion and survival in melanoma that could prove applicable to metastasis of other cancers and suggest that miRNA silencing may be a worthwhile therapeutic strategy.microRNA ͉ cancer ͉ invasion M etastasis is a central problem in cancer, yet the mechanisms underlying a cell's ability to extravasate from the primary tumor, circulate, and invade new tissue remain poorly understood. We reasoned that melanoma, one of the most notoriously invasive neoplasia, would provide an excellent model for investigating the alterations that contribute to metastasis. Melanomas are characterized by certain well-defined genetic alterations (reviewed in ref. 1) as well as frequent chromosomal aberrations associated with tumor progression (2). Recent work has also shown that melanomas display genomic alterations involving numerous microRNA genes (3). MicroRNAs (miRNAs) are endogenous noncoding small RNAs that interfere with the translation of coding messenger RNAs (mRNAs) in a sequence-specific manner (4), often to regulate processes involved in development or tissue homeostasis (5-7). Intriguingly, dysregulation of miRNAs has been found to contribute to neoplasia (8). We decided to investigate the possible contributions of miRNA dysregulation to melanoma extravasation, migration, and invasion.We compared the expression of miRNAs in a large cohort of melanoma cell lines with that of normal melanocytes. We found that miR-182, flanked by the c-MET and BRAF oncogenes in the 7q31-34 region that is frequently amplified in melanoma (9, 10), is highly expressed in metastatic melanoma cell lines and tumors, often in association with increased copy number. Moreover, we demonstrate that antisense-mediated repression of miR-182 inhibited invasion and induced melanoma cell death, whereas ectopic miR-182 up-regulation enhanced the oncogenic activity of melanoma cells in vitro ...

Human uterine leiomyomas (ULMs) are the most common neoplasms of women. Many genes are dysregulated in ULMs and some of this dysregulation may be due to abnormal expression of micro-RNAs (miRNAs). In this study, 55 ULMs and matched myometrium were collected from 41 patients for microarray-based global miRNA expression analysis. Of 206 miRNAs examined, 45 miRNAs were significantly up- or down-regulated in ULMs in comparison to the matched myometrium (P < 0.001). The top five dysregulated miRNAs in ULMs are the let-7 family, miR-21, miR-23b, miR-29b, and miR-197. Four polycistronic clusters of miRNAs were either up- or down-regulated, but not in a mixed pattern, indicative of coordinated regulation of these miRNAs. Significance analysis revealed that subsets of miRNAs were strongly associated with tumor sizes and race. By prediction analysis we identified some important tumorigenic genes previously identified in ULMs that may be targeted by the dysregulated miRNAs. HMGA2 was identified as one of target genes of the let-7 family of miRNAs and has been found to be suppressed by let-7 in vitro. This article contains Supplementary material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

SUMO is a novel ubiquitin-like protein that can covalently modify a large number of nuclear proteins. SUMO modification has emerged as an important regulatory mechanism for protein function and localization. Sumoylation is a dynamic process that is mediated by activating (E1), conjugating (E2), and ligating (E3) enzymes and is readily reversed by a family of SUMO-specific proteases (SENPs). Since SUMO was discovered 10 years ago, the biologic contribution of this posttranslational modification has remained unclear. In this review, we report that SENP1, a member of the SENP family, is overexpressed in human prostate cancer specimens. The induction of SENP1 is observed with the chronic exposure of prostate cancer cells to androgen and/or interleukin (IL) 6. SENP1 upregulation modulates the transcriptional activity of androgen receptors (ARs) and c-Jun, as well as cyclin D1 expression. Initial in vivo data from transgenic mice indicate that overexpression of SENP1 in the prostate leads to the development of prostatic intraepithelial neoplasia at an early age. Collectively, these studies indicate that overexpression of SENP1 is associated with prostate cancer development.

Constitutively-active androgen receptor splice variants (AR-V) lacking the ligand-binding domain have been implicated in the pathogenesis of castration-resistant prostate cancer and in mediating resistance to newer drugs that target the androgen axis. AR-V regulate expression of both canonical AR targets and a unique set of cancer-specific targets that are enriched for cell cycle functions. However, little is known about how AR-V control gene expression. Here we report that two major AR-V, termed AR-V7 and ARv567es, not only homodimerize and heterodimerize with each other but also heterodimerize with full-length androgen receptor (AR-FL) in an androgen-independent manner. We found that heterodimerization of AR-V and AR-FL was mediated by N- and C-terminal interactions and by the DNA-binding domain of each molecule, whereas AR-V homodimerization was mediated only by DNA-binding domain interactions. Notably, AR-V dimerization was required to transactivate target genes and to confer castration-resistant cell growth. Our results clarify the mechanism by which AR-V mediate gene regulation and provide a pivotal pathway for rational drug design to disrupt AR-V signaling, as a rational strategy for effective treatment of advanced prostate cancer.

Analysis of intragenomic variation of 16S rRNA genes is a unique approach to examining the concept of ribosomal constraints on rRNA genes; the degree of variation is an important parameter to consider for estimation of the diversity of a complex microbiome in the recently initiated Human Microbiome Project (http://nihroadmap.nih.gov/hmp). The current GenBank database has a collection of 883 prokaryotic genomes representing 568 unique species, of which 425 species contained 2 to 15 copies of 16S rRNA genes per genome (2.22 ؎ 0.81). Sequence diversity among the 16S rRNA genes in a genome was found in 235 species (from 0.06% to 20.38%; 0.55% ؎ 1.46%). Compared with the 16S rRNA-based threshold for operational definition of species (1 to 1.3% diversity), the diversity was borderline (between 1% and 1.3%) in 10 species and >1.3% in 14 species. The diversified 16S rRNA genes in Haloarcula marismortui (diversity, 5.63%) and Thermoanaerobacter tengcongensis (6.70%) were highly conserved at the 2°structure level, while the diversified gene in B. afzelii (20.38%) appears to be a pseudogene. The diversified genes in the remaining 21 species were also conserved, except for a truncated 16S rRNA gene in "Candidatus Protochlamydia amoebophila." Thus, this survey of intragenomic diversity of 16S rRNA genes provides strong evidence supporting the theory of ribosomal constraint. Taxonomic classification using the 16S rRNA-based operational threshold could misclassify a number of species into more than one species, leading to an overestimation of the diversity of a complex microbiome. This phenomenon is especially seen in 7 bacterial species associated with the human microbiome or diseases.

No abstract

Molecular pathogenesis of high-grade serous ovarian carcinoma (HG-SOC) is poorly understood. Recent recognition of HG-SOC precursor lesions, defined as serous tubal intraepithelial carcinoma (STIC) in fimbria, provides a new venue for the study of early genetic changes in HG-SOC. Using microRNA profiling analysis, we found that miR-182 expression was significantly higher in STIC than in matched normal Fallopian tube. Further study revealed that miR-182 was significantly overexpressed in most HG-SOC cases. To test whether miR-182 plays a major role in early tumourigenesis of HG-SOC, we overexpressed miR-182 in immortalized ovarian surface, Fallopian tube secretory cells and malignant ovarian cell lines, and found that miR-182 overexpression resulted in increased tumour transformation in vitro, and enhanced tumour invasiveness in vitro and metastasis in vivo. Mechanistically, we demonstrated that the oncogenic properties of miR-182 in ovarian cancer were mediated in part by its impaired repair of DNA double-strand breaks and negative regulation of breast cancer 1 (BRCA1) and metastasis suppressor 1 (MTSS1) expression as well as its positive regulation of the oncogene high-mobility group AT-hook 2 (HMGA2). Our findings suggest that miR-182 dysregulation confers powerful oncogenic potential in the tumourigenesis of HG-SOC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

HMGA2, a high-mobility-group AT-hook protein, is an oncogene involved in tumorigenesis of many malignant neoplasms. HMGA2 overexpression is common in both early and later stage of high grade ovarian serous papillary carcinoma. To test whether HMGA2 participates in the initiation of ovarian cancer and promotion of aggressive tumor growth, we examined the oncogenic properties of HMGA2 in ovarian surface epithelial (OSE) cell lines. We found that introduction of HMGA2 overexpression was sufficient to induce OSE transformation in vitro. HMGA2-mediated OSE transformation resulted in tumor formation in xenografts of nude mice. By silencing HMGA2 in HMGA2 overexpressing OSE and ovarian cancer cell lines, the aggressiveness of tumor cell growth behaviors was partially suppressed. Global gene profiling analyses revealed that HMGA2-mediated tumorigenesis was associated with expression changes of target genes and microRNAs that are involved in epithelial-to-mesenchymal transition (EMT). Lumican (LUM), a tumor suppressor that inhibits EMT, was found to be transcriptionally repressed by HMGA2 and was frequently lost in human high-grade serous papillary carcinoma.