Staufen1 Represses the FOXA1-Regulated Transcriptome by Destabilizing FOXA1 mRNA in Colorectal Cancer Cells

Transcription factors play key roles in development and disease by controlling gene expression. Forkhead box A1 (FOXA1), is a pioneer transcription factor essential for mouse development and functions as an oncogene in prostate and breast cancer. In colorectal cancer (CRC), FOXA1 is significantly downregulated and high FOXA1 expression is associated with better prognosis, suggesting potential tumor suppressive functions. We therefore investigated the regulation of FOXA1 expression in CRC, focusing on well-differentiated CRC cells, where FOXA1 is robustly expressed. Genome-wide RNA stability assays identified FOXA1 as an unstable mRNA in CRC cells. We validated FOXA1 mRNA instability in multiple CRC cell lines and in patient-derived CRC organoids, and found that the FOXA1 3'UTR confers instability to the FOXA1 transcript. RNA pulldowns and mass spectrometry identified Staufen1 (STAU1) as a potential regulator of FOXA1 mRNA. Indeed, STAU1 knockdown resulted in increased FOXA1 mRNA and protein expression due to increased FOXA1 mRNA stability. Consistent with these data, RNA-seq following STAU1 knockdown in CRC cells revealed that FOXA1 targets were upregulated upon STAU1 knockdown. Collectively, this study uncovers a molecular mechanism by which FOXA1 is regulated in CRC cells and provides insights into our understanding of the complex mechanisms of gene regulation in cancer.

Benzomorphan and non-benzomorphan agonists differentially alter sigma-1 receptor quaternary structure, as does types of cellular stress

Sigma-1 receptor (S1R) is a calcium-sensitive, ligand-operated receptor chaperone present on the endoplasmic reticulum (ER) membrane. S1R plays an important role in ER-mitochondrial inter-organelle calcium signaling and cell survival. S1R and its agonists confer resilience against various neurodegenerative diseases; however, the molecular mechanism of S1R is not yet fully understood. At resting state, S1R is either in a monomeric or oligomeric state but the ratio of these concentrations seems to change upon activation of S1R. S1R is activated by either cellular stress, such as ER-calcium depletion, or ligands. While the effect of ligands on S1R quaternary structure remains unclear, the effect of cellular stress has not been studied. In this study we utilize cellular and an in-vivo model to study changes in quaternary structure of S1R upon activation. We incubated cells with cellular stressors (H2O2 and thapsigargin) or exogenous ligands, then quantified monomeric and oligomeric forms. We observed that benzomorphan-based S1R agonists induce monomerization of S1R and decrease oligomerization, which was confirmed in the liver tissue of mice injected with (+)-Pentazocine. Antagonists block this effect but do not induce any changes when used alone. Oxidative stress (H2O2) increases the monomeric/oligomeric S1R ratio whereas ER calcium depletion (thapsigargin) has no effect. We also analyzed the oligomerization ability of various truncated S1R fragments and identified the fragments favorizing oligomerization. In this publication we demonstrate that quaternary structural changes differ according to the mechanism of S1R activation. Therefore, we offer a novel perspective on S1R activation as a nuanced phenomenon dependent on the type of stimulus.

Noncoding RNA circuitry in melanoma onset, plasticity, and therapeutic response

Melanoma, the cancer of the melanocyte, is the deadliest form of skin cancer with an aggressive nature, propensity to metastasize and tendency to resist therapeutic intervention. Studies have identified that the re-emergence of developmental pathways in melanoma contributes to melanoma onset, plasticity, and therapeutic response. Notably, it is well known that noncoding RNAs play a critical role in the development and stress response of tissues. In this review, we focus on the noncoding RNAs, including microRNAs, long non-coding RNAs, circular RNAs, and other small RNAs, for their functions in developmental mechanisms and plasticity, which drive onset, progression, therapeutic response and resistance in melanoma. Going forward, elucidation of noncoding RNA-mediated mechanisms may provide insights that accelerate development of novel melanoma therapies.

Matrin3 regulates mitotic spindle dynamics by controlling alternative splicing of CDC14B

Matrin3 is an RNA-binding protein that regulates diverse RNA-related processes, including mRNA splicing. Although Matrin3 has been intensively studied in neurodegenerative diseases, its function in cancer remains unclear. Here, we report Matrin3-mediated regulation of mitotic spindle dynamics in colorectal cancer (CRC) cells. We comprehensively identified RNAs bound and regulated by Matrin3 in CRC cells and focused on CDC14B, one of the top Matrin3 targets. Matrin3 knockdown results in increased inclusion of an exon containing a premature termination codon in the CDC14B transcript and simultaneous down-regulation of the standard CDC14B transcript. Knockdown of CDC14B phenocopies the defects in mitotic spindle dynamics upon Matrin3 knockdown, and the elongated and misoriented mitotic spindle observed upon Matrin3 knockdown are rescued upon overexpression of CDC14B, suggesting that CDC14B is a key downstream effector of Matrin3. Collectively, these data reveal a role for the Matrin3/CDC14B axis in control of mitotic spindle dynamics.

HNRNPH1 destabilizes the G-quadruplex structures formed by G-rich RNA sequences that regulate the alternative splicing of an oncogenic fusion transcript

In the presence of physiological monovalent cations, thousands of RNA G-rich sequences can form parallel G-quadruplexes (G4s) unless RNA-binding proteins inhibit, destabilize, or resolve the formation of such secondary RNA structures. Here, we have used a disease-relevant model system to investigate the biophysical properties of the RNA-binding protein HNRNPH1's interaction with G-rich sequences. We demonstrate the importance of two EWSR1-exon 8 G-rich regions in mediating the exclusion of this exon from the oncogenic EWS-FLI1 transcripts expressed in a subset of Ewing sarcomas, using complementary analysis of tumor data, long-read sequencing, and minigene studies. We determined that HNRNPH1 binds the EWSR1-exon 8 G-rich sequences with low nM affinities irrespective of whether in a non-G4 or G4 state but exhibits different kinetics depending on RNA structure. Specifically, HNRNPH1 associates and dissociates from G4-folded RNA faster than the identical sequences in a non-G4 state. Importantly, we demonstrate using gel shift and spectroscopic assays that HNRNPH1, particularly the qRRM1-qRRM2 domains, destabilizes the G4s formed by the EWSR1-exon 8 G-rich sequences in a non-catalytic fashion. Our results indicate that HNRNPH1's binding of G-rich sequences favors the accumulation of RNA in a non-G4 state and that this contributes to its regulation of RNA processing.

Inflammatory myoglandular polyp as a cause of recurrent abdominal pain in a patient with quiescent Crohn's disease

Chronic inflammation of the intestinal mucosa has been associated with the appearance of inflammatory polyps or pseudopolyps. Among the distinct categories of inflammatory polyps are inflammatory myoglandular polyps (IMGP) usually found in the colorectum. Only one case of IMGP in the terminal ileus has been described since their first description. We report the first case of an inflammatory polyp with both hyperplastic and myoglandular histological characteristics, in the terminal ileum of a patient with quiescent Crohn's disease, causing recurrent intussusception.

Significance of lncRNA abundance to function

Long noncoding RNAs (lncRNAs) have emerged as regulators of diverse cellular processes. Although the vast majority of lncRNAs are expressed at lower levels compared to messenger RNAs (mRNAs), many lncRNAs play a central role in the regulation of cellular homeostasis and gene expression. With the advancement of next generation sequencing technologies, recent studies illustrate the diversity of lncRNA function. This diversity can be due to differences in their mechanisms of action, spatio-temporal expression, and/or abundance, all of which can vary depending on the particular cell type or tissue. Here, we discuss how the abundance of lncRNAs is an important feature that is often linked to their functions, and why it is crucial to quantitate lncRNA abundance, its local concentration within a cell or a tissue or the dynamic changes in expression levels during cell cycle progression or upon environmental stimuli, to shed light on their physiological roles.

AUF1 ligand circPCNX reduces cell proliferation by competing with p21 mRNA to increase p21 production

Mammalian circRNAs can influence different cellular processes by interacting with proteins and other nucleic acids. Here, we used ribonucleoprotein immunoprecipitation (RIP) analysis to identify systematically the circRNAs associated with the cancer-related protein AUF1. Among the circRNAs interacting with AUF1 in HeLa (human cervical carcinoma) cells, we focused on hsa_circ_0032434 (circPCNX), an abundant target of AUF1. Overexpression of circPCNX specifically interfered with the binding of AUF1 to p21 (CDKN1A) mRNA, thereby promoting p21 mRNA stability and elevating the production of p21, a major inhibitor of cell proliferation. Conversely, silencing circPCNX increased AUF1 binding to p21 mRNA, reducing p21 production and promoting cell division. Importantly, eliminating the AUF1-binding region of circPCNX abrogated the rise in p21 levels and rescued proliferation. Therefore, we propose that the interaction of circPCNX with AUF1 selectively prevents AUF1 binding to p21 mRNA, leading to enhanced p21 mRNA stability and p21 protein production, thereby suppressing cell growth.

The p53-induced RNA-binding protein ZMAT3 is a splicing regulator that inhibits the splicing of oncogenic CD44 variants in colorectal carcinoma

p53 is an intensely studied tumor-suppressive transcription factor. Recent studies suggest that the RNA-binding protein (RBP) ZMAT3 is important in mediating the tumor-suppressive effects of p53. Here, we globally identify ZMAT3-regulated RNAs and their binding sites at nucleotide resolution in intact colorectal cancer (CRC) cells. ZMAT3 binds to thousands of mRNA precursors, mainly at intronic uridine-rich sequences and affects their splicing. The strongest alternatively spliced ZMAT3 target was CD44, a cell adhesion gene and stem cell marker that controls tumorigenesis. Silencing ZMAT3 increased inclusion of CD44 variant exons, resulting in significant up-regulation of oncogenic CD44 isoforms (CD44v) and increased CRC cell growth that was rescued by concurrent knockdown of CD44v Silencing p53 phenocopied the loss of ZMAT3 with respect to CD44 alternative splicing, suggesting that ZMAT3-mediated regulation of CD44 splicing is vital for p53 function. Collectively, our findings uncover a p53-ZMAT3-CD44 axis in growth suppression in CRC cells.

A small protein encoded by a putative lncRNA regulates apoptosis and tumorigenicity in human colorectal cancer cells

Long noncoding RNAs (lncRNAs) are often associated with polysomes, indicating coding potential. However, only a handful of endogenous proteins encoded by putative lncRNAs have been identified and assigned a function. Here, we report the discovery of a putative gastrointestinal-tract-specific lncRNA (LINC00675) that is regulated by the pioneer transcription factor FOXA1 and encodes a conserved small protein of 79 amino acids which we termed FORCP (FOXA1-Regulated Conserved Small Protein). FORCP transcript is undetectable in most cell types but is abundant in well-differentiated colorectal cancer (CRC) cells where it functions to inhibit proliferation, clonogenicity, and tumorigenesis. The epitope-tagged and endogenous FORCP protein predominantly localizes to the endoplasmic reticulum (ER). In response to ER stress, FORCP depletion results in decreased apoptosis. Our findings on the initial characterization of FORCP demonstrate that FORCP is a novel, conserved small protein encoded by a mis-annotated lncRNA that regulates apoptosis and tumorigenicity in well-differentiated CRC cells.

Loss of miR-451a enhances SPARC production during myogenesis

MicroRNAs (miRNAs) are small noncoding RNAs that critically regulate gene expression. Their abundance and function have been linked to a range of physiologic and pathologic processes. In aged monkey muscle, miR-451a and miR-144-3p were far more abundant than in young monkey muscle. This observation led us to hypothesize that miR-451a and miR-144-3p may influence muscle homeostasis. To test if these conserved microRNAs were implicated in myogenesis, we investigated their function in the mouse myoblast line C2C12. The levels of both microRNAs declined with myogenesis; however, only overexpression of miR-451a, but not miR-144-3p, robustly impeded C2C12 differentiation, suggesting an inhibitory role for miR-451a in myogenesis. Further investigation of the regulatory influence of miR-451a identified as one of the major targets Sparc mRNA, which encodes a secreted protein acidic and rich in cysteine (SPARC) that functions in wound healing and cellular differentiation. In mouse myoblasts, miR-451a suppressed Sparc mRNA translation. Together, our findings indicate that miR-451a is downregulated in differentiated myoblasts and suggest that it decreases C2C12 differentiation at least in part by suppressing SPARC biosynthesis.

Hallmarks in the evolution of gynaecological cancer surgery: the famous pioneers in children

At the beginning of the 19th century, gynaecological cancer, mainly cancer of the uterus and cervix was a dreadful, incurable affection. However, the popularization of the three fundamentals in surgery, anesthesia, asepsis and haemostasis, ushered the golden age of operative gynaecology. During that period distinguished surgeons/gynaecologists such as Friedrich Benjamin Osiander (1759-1822), Elias von Siebold (1775-1828) and Joseph-Claude-Anthelme Récamier (1774-1852) contributed to the development of the operative techniques, providing a therapeutic solution in gynaecological cancer.

High-purity circular RNA isolation method (RPAD) reveals vast collection of intronic circRNAs

High-throughput RNA sequencing methods coupled with specialized bioinformatic analyses have recently uncovered tens of thousands of unique circular (circ)RNAs, but their complete sequences, genes of origin and functions are largely unknown. Given that circRNAs lack free ends and are thus relatively stable, their association with microRNAs (miRNAs) and RNA-binding proteins (RBPs) can influence gene expression programs. While exoribonuclease treatment is widely used to degrade linear RNAs and enrich circRNAs in RNA samples, it does not efficiently eliminate all linear RNAs. Here, we describe a novel method for the isolation of highly pure circRNA populations involving RNase R treatment followed by Polyadenylation and poly(A)⁺ RNA Depletion (RPAD), which removes linear RNA to near completion. High-throughput sequencing of RNA prepared using RPAD from human cervical carcinoma HeLa cells and mouse C2C12 myoblasts led to two surprising discoveries: (i) many exonic circRNA (EcircRNA) isoforms share an identical backsplice sequence but have different body sizes and sequences, and (ii) thousands of novel intronic circular RNAs (IcircRNAs) are expressed in cells. In sum, isolating high-purity circRNAs using the RPAD method can enable quantitative and qualitative analyses of circRNA types and sequence composition, paving the way for the elucidation of circRNA functions.

Identification of senescence-associated circular RNAs (SAC-RNAs) reveals senescence suppressor CircPVT1

Using RNA sequencing (RNA-Seq), we compared the expression patterns of circular RNAs in proliferating (early-passage) and senescent (late-passage) human diploid WI-38 fibroblasts. Among the differentially expressed senescence-associated circRNAs (which we termed ‘SAC-RNAs’), we identified CircPVT1, generated by circularization of an exon of the PVT1 gene, as a circular RNA showing markedly reduced levels in senescent fibroblasts. Reducing CircPVT1 levels in proliferating fibroblasts triggered senescence, as determined by a rise in senescence-associated β-galactosidase activity, higher abundance of CDKN1A/P21 and TP53, and reduced cell proliferation. Although several microRNAs were predicted to bind CircPVT1, only let-7 was found enriched after pulldown of endogenous CircPVT1, suggesting that CircPVT1 might selectively modulate let-7 activity and hence expression of let-7-regulated mRNAs. Reporter analysis revealed that CircPVT1 decreased the cellular pool of available let-7, and antagonizing endogenous let-7 triggered cell proliferation. Importantly, silencing CircPVT1 promoted cell senescence and reversed the proliferative phenotype observed after let-7 function was impaired. Consequently, the levels of several proliferative proteins that prevent senescence, such as IGF2BP1, KRAS and HMGA2, encoded by let-7 target mRNAs, were reduced by silencing CircPVT1. Our findings indicate that the SAC-RNA CircPVT1, elevated in dividing cells and reduced in senescent cells, sequesters let-7 to enable a proliferative phenotype.

Senescence-Associated MicroRNAs

Senescent cells arise as a consequence of cellular damage and can have either a detrimental or advantageous impact on tissues and organs depending on the specific cell type and metabolic state. As senescent cells accumulate in tissues with advancing age, they have been implicated in many age-related declines and diseases. The major facets of senescence include two pathways responsible for establishing and maintaining a senescence program, p53/CDKN1A(p21) and CDKN2A(p16)/RB, as well as the senescence-associated secretory phenotype. Numerous MicroRNAs influence senescence by modulating the abundance of key senescence regulatory proteins, generally by lowering the stability and/or translation of mRNAs that encode such factors. Accordingly, understanding the molecular mechanisms by which MicroRNAs influence senescence will enable diagnostic and therapeutic opportunities directed at senescent cells. Here, we review senescence-associated (SA)-MicroRNAs and discuss their implications in senescence-relevant pathologies.

Abstract IA04: Control of cell senescence by cancer-associated protein HuR and target noncoding RNAs

Senescent cells accumulate in aging tissues, and their metabolic and gene expression profiles are linked to cancer and other age-associated pathologies. Our recent studies have focused on the cancer-associated RNA-binding protein HuR [1], a suppressor of senescence, and its interaction with different classes of noncoding RNAs—long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs). I discuss the ribonucleoprotein (RNP) complexes that HuR forms with several noncoding RNAs that influence protein abundance and modulate the senescent phenotype. HuR association with lncRNAs such as LINCP21 suppresses the translation of select mRNAs [2], its interaction with lncRNA HOTAIR promotes the ubiquitin-mediated proteolysis of select proteins [3], and its association with RMRP enhances mitochondrial homeostasis [4], while its competition with 7SL modulates TP53 mRNA translation [5]. Likewise, HuR can bind microRNAs like let-7, which can function as tumor suppressors [6], modulating their availability to repress mRNAs bearing let-7 sites. Finally, our ongoing studies show that HuR can also bind circRNAs, an interaction that reduces the expression of select proliferative proteins and reduces cell division. In summary, HuR is well known for regulating target mRNAs encoding proteins that modulate cancer traits [1], but growing evidence indicates that HuR also regulates many target noncoding RNAs that govern protein expression patterns affecting growth arrest and cell senescence.

References:

[1] Abdelmohsen and Gorospe, WIRES RNA 2010

[2] Yoon et al., Mol Cell, 2012

[3] Yoon et al., Nat Commun, 2013

[4] Noh et al., Genes Dev, 2016

[5] Abdelmohsen et al., Nucleic Acids Res, 2014

[6] Yoon et al., Genes Dev 2015

Citation Format: Kotb Abdelmohsen, Amaresh C. Panda, Ioannis Grammatikakis, Ji Heon Noh, Myriam Gorospe. Control of cell senescence by cancer-associated protein HuR and target noncoding RNAs. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr IA04.

Identification of HuR target circular RNAs uncovers suppression of PABPN1 translation by CircPABPN1

HuR influences gene expression programs and hence cellular phenotypes by binding to hundreds of coding and noncoding linear RNAs. However, whether HuR binds to circular RNAs (circRNAs) and impacts on their function is unknown. Here, we have identified en masse circRNAs binding HuR in human cervical carcinoma HeLa cells. One of the most prominent HuR target circRNAs was hsa_circ_0031288, renamed CircPABPN1 as it arises from the PABPN1 pre-mRNA. Further analysis revealed that HuR did not influence CircPABPN1 abundance; interestingly, however, high levels of CircPABPN1 suppressed HuR binding to PABPN1 mRNA. Evaluation of PABPN1 mRNA polysomes indicated that PABPN1 translation was modulated positively by HuR and hence negatively by CircPABPN1. We propose that the extensive binding of CircPABPN1 to HuR prevents HuR binding to PABPN1 mRNA and lowers PABPN1 translation, providing the first example of competition between a circRNA and its cognate mRNA for an RBP that affects translation.

CircInteractome: A web tool for exploring circular RNAs and their interacting proteins and microRNAs

Circular RNAs (circRNAs) are widely expressed in animal cells, but their biogenesis and functions are poorly understood. CircRNAs have been shown to act as sponges for miRNAs and may also potentially sponge RNA-binding proteins (RBPs) and are thus predicted to function as robust posttranscriptional regulators of gene expression. The joint analysis of large-scale transcriptome data coupled with computational analyses represents a powerful approach to elucidate possible biological roles of ribonucleoprotein (RNP) complexes. Here, we present a new web tool, CircInteractome (circRNA interactome), for mapping RBP- and miRNA-binding sites on human circRNAs. CircInteractome searches public circRNA, miRNA, and RBP databases to provide bioinformatic analyses of binding sites on circRNAs and additionally analyzes miRNA and RBP sites on junction and junction-flanking sequences. CircInteractome also allows the user the ability to (1) identify potential circRNAs which can act as RBP sponges, (2) design junction-spanning primers for specific detection of circRNAs of interest, (3) design siRNAs for circRNA silencing, and (4) identify potential internal ribosomal entry sites (IRES). In sum, the web tool CircInteractome, freely accessible at http://circinteractome.nia.nih.gov, facilitates the analysis of circRNAs and circRNP biology.

Circular RNAs in monkey muscle: age-dependent changes

Circular RNAs (circRNAs) have been identified in numerous species, including human, mouse, nematode, and coelacanth. They are believed to function as regulators of gene expression at least in part by sponging microRNAs. Here, we describe the identification of circRNAs in monkey (Rhesus macaque) skeletal muscle. RNA sequencing analysis was employed to identify and annotate ∼12,000 circRNAs, including numerous circular intronic RNAs (ciRNAs), from skeletal muscle of monkeys of a range of ages. Reverse transcription followed by real-time quantitative (q)PCR analysis verified the presence of these circRNAs, including the existence of several highly abundant circRNAs, and the differential abundance of a subset of circRNAs as a function of age. Taken together, our study has documented systematically circRNAs expressed in skeletal muscle and has identified circRNAs differentially abundant with advancing muscle age. We propose that some of these circRNAs might influence muscle function.

Emerging roles and context of circular RNAs

Circular RNAs (circRNAs) represent a large class of noncoding RNAs (ncRNAs) that have recently emerged as regulators of gene expression. They have been shown to suppress microRNAs, thereby increasing the translation and stability of the targets of such microRNAs. In this review, we discuss the emerging functions of circRNAs, including RNA transcription, splicing, turnover, and translation. We also discuss other possible facets of circRNAs that can influence their function depending on the cell context, such as circRNA abundance, subcellular localization, interacting partners (RNA, DNA, and proteins), dynamic changes in interactions following stimulation, and potential circRNA translation. The ensuing changes in gene expression patterns elicited by circRNAs are proposed to drive key cellular processes, such as cell proliferation, differentiation, and survival, that govern health and disease. WIREs RNA 2017, 8:e1386. doi: 10.1002/wrna.1386 For further resources related to this article, please visit the WIREs website.

The long and the short of TRF2 in neurogenesis

Gene expression patterns change dramatically during neuronal development. Proliferating cells, including neural stem cells (NSCs), express telomere repeat-binding factor 2 (TRF2), a nuclear protein that associates with telomeric proteins, DNA, and RNA telomeres. In NSCs TRF2 also binds to the transcription regulator REST to facilitate repression of numerous neuron-specific genes, thereby keeping the NSCs in a self-renewing state. Upon neuronal differentiation, TRF2 levels decline, REST-regulated neuronal genes are derepressed, and a short isoform of TRF2 arises (TRF2-S) which localizes in the cytoplasm, associates with different subsets of proteins and transcripts, and mobilizes axonal G-rich mRNAs. We recently identified two RNA-binding proteins, HNRNPH1 and H2 (referred to jointly as HNRNPH due to their high homology), which mediate the alternative splicing of an exon required for the expression of full-length TRF2. As HNRNPH levels decline during neurogenesis, TRF2 abundance decreases and TRF2-S accumulates. Here, we discuss the shared and unique functions of TRF2 and TRF2-S, the distinct subcellular compartment in which each isoform resides, the subsets of proteins and nucleic acids with which each interacts, and the functional consequences of these ribonucleoprotein interactions. This paradigm illustrates the dynamic mechanisms through which splicing regulation by factors like HNRNPH enable distinct protein functions as cells adapt to developmental programs such as neurogenesis.

Posttranslational control of HuR function

The RNA-binding protein HuR (human antigen R) associates with numerous transcripts, coding and noncoding, and controls their splicing, localization, stability, and translation. Through its regulation of target transcripts, HuR has been implicated in cellular events including proliferation, senescence, differentiation, apoptosis, and the stress and immune responses. In turn, HuR influences processes such as cancer and inflammation. HuR function is primarily regulated through posttranslational modifications that alter its subcellular localization and its ability to bind target RNAs; such modifications include phosphorylation, methylation, ubiquitination, NEDDylation, and proteolytic cleavage. In this review, we describe the modifications that impact upon HuR function on gene expression programs and disease states. WIREs RNA 2017, 8:e1372. doi: 10.1002/wrna.1372 For further resources related to this article, please visit the WIREs website.

Alternative Splicing of Neuronal Differentiation Factor TRF2 Regulated by HNRNPH1/H2

During neuronal differentiation, use of an alternative splice site on the rat telomere repeat-binding factor 2 (TRF2) mRNA generates a short TRF2 protein isoform (TRF2-S) capable of derepressing neuronal genes. However, the RNA-binding proteins (RBPs) controlling this splicing event are unknown. Here, using affinity pull-down analysis, we identified heterogeneous nuclear ribonucleoproteins H1 and H2(HNRNPH) as RBPs specifically capable of interacting with the spliced RNA segment (exon 7) of Trf2 pre-mRNA. HNRNPH proteins prevent the production of the short isoform of Trf2 mRNA, as HNRNPH silencing selectively elevates TRF2-S levels. Accordingly, HNRNPH levels decline while TRF2-S levels increase during neuronal differentiation. In addition, CRISPR/Cas9-mediated deletion of hnRNPH2 selectively accelerates the NGF-triggered differentiation of rat pheochromocytoma cells into neurons. In sum, HNRNPH is a splicing regulator of Trf2 pre-mRNA that prevents the expression of TRF2-S, a factor implicated in neuronal differentiation.

Identification of neural stem cell differentiation repressor complex Pnky-PTBP1

Splicing increases immensely the complexity of gene products expressed in the cell. The precise regulation of splicing is critical for the development, homeostasis, and function of all tissues in the body, including those comprising the neural system. Ramos et al. recently identified Pnky as a long noncoding RNA expressed selectively in neural tissues that was implicated in the transition of neural stem cells (NSCs) to mature neurons. Pnky actions appeared to be mediated by its interaction with the splicing factor and RNA-binding protein (RBP) polypyrimidine tract-binding protein (PTBP1), as silencing either Pnky or PTBP1 modulated in similar ways the patterns of spliced and expressed mRNAs in the cell. Strikingly, lowering the expression levels of Pnky or PTBP1 in NSCs actually enhanced neurogenesis, suggesting that the Pnky-PTBP1 complex elicited a splicing program of suppression of neurogenesis. With rapid progress in the design and delivery of RNA-based therapies, interventions to reduce Pnky levels may prove beneficial towards enhancing neurogenesis in disease states characterized by aberrant neuronal loss.

Novel RNA-binding activity of MYF5 enhances Ccnd1/Cyclin D1 mRNA translation during myogenesis

Skeletal muscle contains long multinucleated and contractile structures known as muscle fibers, which arise from the fusion of myoblasts into multinucleated myotubes during myogenesis. The myogenic regulatory factor (MRF) MYF5 is the earliest to be expressed during myogenesis and functions as a transcription factor in muscle progenitor cells (satellite cells) and myocytes. In mouse C2C12 myocytes, MYF5 is implicated in the initial steps of myoblast differentiation into myotubes. Here, using ribonucleoprotein immunoprecipitation (RIP) analysis, we discovered a novel function for MYF5 as an RNA-binding protein which associated with a subset of myoblast mRNAs. One prominent MYF5 target was Ccnd1 mRNA, which encodes the key cell cycle regulator CCND1 (Cyclin D1). Biotin-RNA pulldown, UV-crosslinking and gel shift experiments indicated that MYF5 was capable of binding the 3' untranslated region (UTR) and the coding region (CR) of Ccnd1 mRNA. Silencing MYF5 expression in proliferating myoblasts revealed that MYF5 promoted CCND1 translation and modestly increased transcription of Ccnd1 mRNA. Accordingly, overexpressing MYF5 in C2C12 cells upregulated CCND1 expression while silencing MYF5 reduced myoblast proliferation as well as differentiation of myoblasts into myotubes. Moreover, MYF5 silencing reduced myogenesis, while ectopically restoring CCND1 abundance partially rescued the decrease in myogenesis seen after MYF5 silencing. We propose that MYF5 enhances early myogenesis in part by coordinately elevating Ccnd1 transcription and Ccnd1 mRNA translation.

LncRNA OIP5-AS1/cyrano sponges RNA-binding protein HuR

The function of the vast majority of mammalian long noncoding (lnc) RNAs remains unknown. Here, analysis of a highly abundant mammalian lncRNA, OIP5-AS1, known as cyrano in zebrafish, revealed that OIP5-AS1 reduces cell proliferation. In human cervical carcinoma HeLa cells, the RNA-binding protein HuR, which enhances cell proliferation, associated with OIP5-AS1 and stabilized it. Tagging OIP5-AS1 with MS2 hairpins to identify associated microRNAs revealed that miR-424 interacted with OIP5-AS1 and competed with HuR for binding to OIP5-AS1. We further identified a ‘sponge’ function for OIP5-AS1, as high levels of OIP5-AS1 increased HuR-OIP5-AS1 complexes and prevented HuR interaction with target mRNAs, including those that encoded proliferative proteins, while conversely, lowering OIP5-AS1 increased the abundance of HuR complexes with target mRNAs. We propose that OIP5-AS1 serves as a sponge or a competing endogenous (ce)RNA for HuR, restricting its availability to HuR target mRNAs and thereby repressing HuR-elicited proliferative phenotypes.

Long noncoding RNAs(lncRNAs) and the molecular hallmarks of aging

During aging, progressive deleterious changes increase the risk of disease and death. Prominent molecular hallmarks of aging are genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, cellular senescence, stem cell exhaustion, and altered intercellular communication. Long noncoding RNAs (lncRNAs) play important roles in a wide range of biological processes, including age-related diseases like cancer, cardiovascular pathologies, and neurodegenerative disorders. Evidence is emerging that lncRNAs influence the molecular processes that underlie age-associated phenotypes. Here, we review our current understanding of lncRNAs that control the development of aging traits.

7SL RNA represses p53 translation by competing with HuR

Noncoding RNAs (ncRNAs) and RNA-binding proteins are potent post-transcriptional regulators of gene expression. The ncRNA 7SL is upregulated in cancer cells, but its impact upon the phenotype of cancer cells is unknown. Here, we present evidence that 7SL forms a partial hybrid with the 3'-untranslated region (UTR) of TP53 mRNA, which encodes the tumor suppressor p53. The interaction of 7SL with TP53 mRNA reduced p53 translation, as determined by analyzing p53 expression levels, nascent p53 translation and TP53 mRNA association with polysomes. Silencing 7SL led to increased binding of HuR to TP53 mRNA, an interaction that led to the promotion of p53 translation and increased p53 abundance. We propose that the competition between 7SL and HuR for binding to TP53 3'UTR contributes to determining the magnitude of p53 translation, in turn affecting p53 levels and the growth-suppressive function of p53. Our findings suggest that targeting 7SL may be effective in the treatment of cancers with reduced p53 levels.

The contribution of sildenafil (Viagra) to ovarian stimulation with gonadotropins in a woman with poor ovarian response

We aim to present the first case of a pregnancy achieved by administering sildenafil (Viagra) to a woman not responding to controlled ovarian hyperstimulation (COH) with the sole use of gonadotropins. A 37-year-old woman underwent COH, as part of an intracytoplasmic sperm injection (ICSI) cycle, with the combination of r-FSH and HMG for 13 d, without evidence of follicular growth. The addition of oral sildenafil at a dose of 50 mg per day for a total of five doses improved the ovarian response and resulted in the retrieval of 10 oocytes. Three embryos were transferred to the uterine cavity resulting in a successful pregnancy and, eventually, the delivery of a healthy neonate. Conclusively, the use of sildenafil as an adjunct to COH protocols may enhance ovarian response in a woman with poor ovarian response (POR) and merits further research.

Tomosynthesis improves breast cancer detection: our experience

Breast tomosynthesis (BT) is a novel imaging technology in which an x-ray fan beam sweeps in an arc across the breast, producing tomographic images and it can reduce tissue overlap encountered in conventional two-dimensional (2D) and thus has the potential to improve detection of breast cancer and facilitate accurate differentiation of lesion types. The purpose of this article was to assess the positive predictive value (PPV) of breast cancer with BT versus full-field digital mammography (FFDM) and the assessment of detec- tion of both techniques in the present series.

Breast conserving surgery in multicentric breast cancer, preliminary data of our experience

INTRODUCTION

It is widely supported that multicentric disease of the breast (MCDB) is a contraindication of breast conservative surgery (BCS).

MATERIALS AND METHODS

This is a multicentric study (two breast cancer units from Greece, one from France) involving patients with at least two primary tumors in separate quadrants of the breast and no diffuse suspicious microcalcifications on mammography. Sixty-one patients were included in the study, but 49 were followed up to the end. Patients were randomly assigned in total mastectomy (TM) and BCS groups. End point of the study was disease-free survival rates three and five years after initial operation.

RESULTS

Three years after BCS, local recurrence (LR) was observed in two patients (7%) and one after five years (total recurrence rate: 11%). A TM was performed in these patients, and in two there was no LR or distant metastasis (DM) five years after. The third patient was disease free two-years later. Three years after TM, eight patients (36.4%) had DM and 14 (63.6%) did not (p = 0.004). Five years after TM, eight patients (36.4%) had DM and 14 patients (63.6%) di not (p = 0.03).

CONCLUSION

The results showed that conservative surgery was an alternative surgical option in multicentric breast cancer with good results regarding disease-free survival and recurrence.

Posttranscriptional regulation of insulin family ligands and receptors

Insulin system including ligands (insulin and IGFs) and their shared receptors (IR and IGFR) are critical regulators of insulin signaling and glucose homeostasis. Altered insulin system is associated with major pathological conditions like diabetes and cancer. The mRNAs encoding for these ligands and their receptors are posttranscriptionally controlled by three major groups of regulators; (i) alternative splicing regulatory factors; (ii) turnover and translation regulator RNA-binding proteins (TTR-RBPs); and (iii) non-coding RNAs including miRNAs and long non-coding RNAs (lncRNAs). In this review, we discuss the influence of these regulators on alternative splicing, mRNA stability and translation. Due to the pathological impacts of insulin system, we also discussed the possibilities of discovering new potential regulators which will improve understanding of insulin system and associated diseases.

Identification of MBNL1 and MBNL3 domains required for splicing activation and repression

Muscleblind-like 1 (MBNL1) is a splicing regulator that controls developmentally regulated alternative splicing of a large number of exons including exon 11 of the Insulin Receptor (IR) gene and exon 5 of the cardiac Troponin T (cTNT) gene. There are three paralogs of MBNL in humans, all of which promote IR exon 11 inclusion and cTNT exon 5 skipping. Here, we identify a cluster of three binding sequences located downstream of IR exon 11 that constitute the MBNL1 response element and a weaker response element in the upstream intron. In addition, we used sequential deletions to define the functional domains of MBNL1 and MBNL3. We demonstrate that the regions required for splicing regulation are separate from the two pairs of zinc-finger RNA-binding domains. MBNL1 and MBNL3 contain core regulatory regions for both activation and repression located within an 80-amino-acid segment located downstream of the N-terminal zinc-finger pair. Deletions of these regions abolished regulation without preventing RNA binding. These domains have common features with the CUG-BP and ETR3-like Factor (CELF) family of splicing regulators. These results have identified protein domains required for splicing repression and activation and provide insight into the mechanism of splicing regulation by MBNL proteins.

mTOR signaling is activated by FLT3 kinase and promotes survival of FLT3-mutated acute myeloid leukemia cells

Activating mutations of the FLT3 gene mediate leukemogenesis, at least in part, through activation of PI3K/AKT. The mammalian target of rapamycin (mTOR)-Raptor signaling pathway is known to act downstream of AKT. Here we show that the mTOR effectors, 4EBP1, p70S6K and rpS6, are highly activated in cultured and primary FLT3-mutated acute myeloid leukemia (AML) cells. Introduction of FLT3-ITD expressing constitutively activated FLT3 kinase further activates mTOR and its downstream effectors in BaF3 cells. We also found that mTOR signaling contributes to tumor cell survival, as demonstrated by pharmacologic inhibition of PI3K/AKT/mTOR, or total silencing of the mTOR gene. Furthermore, inhibition of FLT3 kinase results in downregulation of mTOR signaling associated with decreased survival of FLT3-mutated AML cells. These findings suggest that mTOR signaling operates downstream of activated FLT3 kinase thus contributing to tumor cell survival, and may represent a promising therapeutic target for AML patients with mutated-FLT3.

Synopsis of new antiangiogenetic factors, mutation compensation agents, and monoclonal antibodies in target therapies of breast cancer

Breast cancer is the most common type of cancer among females and the 5th most common cause of cancer death. About 5-10% of breast cancers occur due to gene mutations inherited from mother or father. The molecular basis of breast cancer has been extensively investigated, making gene therapy a potential new therapeutic alternative. Mutation compensation, molecular chemotherapy, proapoptotic gene therapy, antiangiogenic gene therapy, genetic immunopotentiation and genetic modulation of resistance/sensitivity are the main gene therapies used. The combination of gene therapy with chemotherapy or radiation is being investigated in ongoing trials. The purpose of this review was to make a synopsis of the currently existing target therapies in breast cancer.

Augmentation of cortical bone mineral density in women with polycystic ovary syndrome: a peripheral quantitative computed tomography (pQCT) study

BACKGROUND

Women with polycystic ovary syndrome (PCOS) may have increased cortical bone mineral density (BMD) and probably higher bone material quality as well as better resistance in the compression strength of the tibia, measured by peripheral quantitative computed tomography (pQCT), in comparison with that of age-matched healthy subjects.

METHODS

Thirty women with PCOS, (15 lean and 15 obese) and 15 age-matched healthy controls were enrolled in this study. The clinical, biochemical and ultrasound characteristics of the two groups were evaluated. Using pQCT, the following parameters were measured: volumetric cortical density (CBD) and volumetric trabecular density (TBD) BMD, total bone cross-sectional area (ToA), cortical area (CoA), cortical thickness (CRT-THK-C) and finally the strength-strain index (SSI).

RESULTS

The geometrical parameters (CoA, ToA, CRT-THK-C), the SSI as well as the TBD were increased in the PCOS women; however, these differences did not achieve statistical significance between lean PCOS women, obese PCOS women, and controls. Conversely, CBD was significantly higher in PCOS women compared with controls (P < 0.000) and furthermore in lean PCOS women compared with obese ones (P < 0.01040).

CONCLUSIONS

The PCOS women of our study seem to have a higher quality of bone material in the distal tibia and probably a better resistance of bone in the compression strength without alterations in bone mass and geometry (especially the lean PCOS women), indicating that our oligomenorrheic and hyperandrogonemic PCOS women may be protected from the development of osteoporosis and fracture risk later in life.

Metastatic lobular carcinoma of the breast to the vulva: a case report and review of the literature

Primary breast-like vulva cancer, as well as metastatic disease of breast cancer to the vulva are described to be very rare, especially many years after the treatment of the primary breast tumor. Breast cancer rarely metastasizes to the vulva without finding other metastatic sites. We report a case of a 93-year-old woman with an isolated metastatic vulvar nodule thirteen years after the surgical treatment of primary breast cancer. The prior histology was a node negative invasive lobular breast cancer. The histology of the vulvar nodule was similar to the primary breast cancer. No other metastatic sites were found by both clinical examination and imaging. When isolated metastasis to the vulva is found, a primary cancer in the gynaecological area should be excluded first.

KEY WORDS

Breast cancer - Vulvar metastasis - Rare breast metastasis.

Endometrium and ovarian cancer synchronous to endometriosis--a retrospective study of our experience of 7 years

PURPOSE

Although endometriosis is a benign disorder, recent studies suggest that endometriosis could be viewed as a neoplastic process. The objective of this study is to explore the epidemiology of synchronous neoplasms (SPN) in women with severe endometriosis.

PATIENTS & METHODS

The prevalence of SPN in cases with endometriotic ovarian cysts that underwent surgery at "Lito" Maternity Hospital of Athens and at Anticancer Institute of Bucharest was investigated. The review period was from the year 2000 to 2008. The medical records and pathology were reviewed to confirm the diagnosis and stage of tumors.

RESULTS

Five women with synchronous cancer of the genital tract were identified. All of our patients had a grade-I endometrioid carcinoma of the uterus (Ia in 3, Ib in 2). Myometrium was invaded in less than 1/3, in 4 cases, and less than 1/2 in one case. Similarly, 4 out of 5 ovarian cancers were endometrioid, while one was serum cystadenosarcoma. All of the ovarian malignancies were grade I (Ib in 3 and Ia in 2). The median diameter of the ovarian neoplasias was of 4.3 cm, as opposed to 4.5 cm that was the median diameter of all endometrioid cysts. When the larger ovarian malignant cyst in each patient was accounted, the median diameter was calculated as having 5.8 cm.

CONCLUSIONS

Women with synchronous primary cancers of the endometrium and ovary have distinct clinical characteristics including younger age, premenopausal status, and nulliparity. This suggests that a hormonal "field effect" may account for the development of these simultaneous endometrioid cancers, supporting the theory of estrogen receptors.

An update to 21-hydroxylase deficient congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) due to deficiency of the enzyme 21-hydroxylase (21-OH) is distinguished in classical (C-CAH) and non-classical form (NC-CAH), and it is also one of the most common autosomal recessive inherited disorders in humans. The prevalence of C-CAH is between 1:10,000 and 1:15,000 among the live neonates of North America and Europe while the NC-CAH occurs in approximately 0.2% of the general white population. The highest incidence of CAH (1:282 and 1:2141, respectively) has been evaluated in Yupik Eskimos in Alaska and in the populations of the island La Reunion (France), while the lower was detected in New Zealand newborns (0.3%). Nowadays, it has been established that except for the adrenal cortex in CAH cases, the adrenal medulla was also affected. In human 21-OH deficient adrenal gland it has been discovered that not only the chromaffin cells formed extensive neurites, expanding between adrenocortical cells, but also that the adrenal androgens promote outgrowth, whereas glucocorticoids preserve neuroendocrine cells. It seems that normal cortisol secretion by the adrenal cortex is necessary for adrenomedullary organogenesis. The synthesis of 21-OH is controlled by the active CYP21A2 gene located at a distance of 30 kb from a highly homologous pseudogene designated CYP21A1P.

Successful pregnancy after radiotherapy with 131I for differentiated thyroid cancer. A case report and review of the literature

BACKGROUND

Radioactive iodine has been used effectively in the diagnosis and treatment of thyroid diseases. Since radiation is delivered to the whole body, including the ovaries, there is reasonable concern as to whether there is a possibility of mutagenic effect on germ cells.

CASE REPORT

A 33-year-old woman with a differentiated papillary carcinoma. (T2N0M0), underwent radiotherapy three weeks after surgery and one year afterwards she became pregnant. At the 38th week of gestation she delivered vaginally a healthy female neonate weighing 3100 g. The child at the age of five years is healthy with no signs of malignancy or other disease.

DISCUSSION

Washout of 131I of the whole body takes place in a few days. Nevertheless, most guidelines recommend avoiding pregnancy for four to six or even 12 months after RAI treatment or scanning. As reported in our case a normal uncomplicated pregnancy can follow an operative and complementary treatment of thyroid cancer.

[Incidence of synchronous primary neoplasms of the female reproductive tract in women with ovarian endometriosis: a retrospective analysis of 811 cases]

PURPOSE

Although endometriosis is a benign disorder recent studies suggest endometriosis could be viewed as a neoplastic process. Objective of this study is to explore the epidemiology of synchronous neoplasms (SPN) in women with severe endometriosis.

PATIENTS & METHODS

The prevalence of SPN in cases with endometriotic ovarian cysts that underwent surgery at "Lito" Maternity hospital of Athens and at Anticancer Institute of Sophia was investigated. The review period was 2000 through 2009. The medical records and pathology were reviewed to confirm the diagnosis and stage of tumors.

RESULTS

5 women with synchronous cancers of the genital tract were identified. All of our patients had a grade-I endometrioid carcinoma of the uterus (Ia in 3, Ib in 2). Myometrium was invaded less than 1/3 in 4 cases and less than 1/2 in one. Similarly, 4 out of 5 ovarian cancers were endometrioid, while one was serum cystadenosarcoma. All of the ovarian malignancies were grade I (Ib in 3 and Ia in 2). Median diameter of the ovarian neoplasias was 4.3 cm, in contradiction to 4.5 cm that was the median diameter of all endometrioid cysts. When only the larger ovarian malignant cyst in each patient was accounted, then median diameter was calculated as 5.8 cm.

CONCLUSIONS

Women with synchronous primary cancers of the endometrium and ovary have distinct clinical characteristics including younger age, premenopausal status, and nulliparity. This suggests that a hormonal "field effect" may account for the development of these simultaneous endometrioid cancers, supporting the theory of estrogen receptors.

Prevalence of severe pelvic inflammatory disease and endometriotic ovarian cysts: a 7-year retrospective study

INTRODUCTION

The purpose of this study was to delineate the association between endometriosis and pelvic inflammatory disease (PID) and the prevalence of this coexistence.

MATERIALS & METHODS

The records of all patients with endometriotic ovarian cysts treated at the 3rd Department of Obstetrics and Gynecology of the University of Athens and in "Lito" Maternity Hospital of Athens from 2000 through 2007 were reviewed.

RESULTS

During this 7-year period 720 women underwent surgery due to endometriotic ovarian cysts. The average age was 40.9 years (range: 17-70). Median diameter of the cysts was 4.495 cm and 59% were located in the right ovary. PID was identified in 21 (2.9%) cases. The average age of these women was 31 years (range: 21-39). Half of the women presented with fever (10/21; 47.6%). Ultrasound examination was performed in all women, followed by laparoscopy. In 47.6% (10/21) the PID abscess was located in the right ovary and the rest (52.38%) in the left. The mean diameter of the endometriotic cysts in these women was 3.52 cm. Laparoscopy was the treatment of choice in all the women with the exception of five cases, where due to technical difficulties during laparoscopy, a laparotomy was performed. In all the cases with PID, abscesses were evacuated laparoscopically. No operative complications were observed.

CONCLUSIONS

Endometriosis and PID are two conditions that can easily confuse the physician in setting the diagnosis, especially in the situation where they co-exist. In our study we report that the prevalence of PID in women with endometriosis is sufficiently higher than the prevalence in the general population.

Prevalence of acute hemoperitoneum in patients with endometriotic ovarian cysts: a 7-year retrospective study

INTRODUCTION

Endometriosis is a quite common condition in women of reproductive age. The purpose of this study is to delineate the association between hemoperitoneum and endometriosis.

MATERIALS & METHODS

The records of all patients with endometriotic ovarian cysts treated at the 3rd Department of Obstetrics and Gynecology of the University of Athens and at "Lito" Maternity Hospital of Athens from 2000 through 2007 were reviewed.

RESULTS

During this 7-year period 720 women underwent surgery due to endometriotic ovarian cysts. The average age was 40.9 years (range: 17-70). The median diameter of the cysts was 4.49 cm and 59% were located in the right ovary. Hemoperitoneum was identified in 16 (2.22%) of them. The average age of these women was 28.5 years (range: 22-44). Ten (62.5%) of these women presented with acute and strong abdominal pain and moderate signs of cardiovascular shock. The rest presented with abdominal pain and distension worsening at the onset of menses, nausea and/or vomiting and hemorrhagic fluid in the pelvis. Ultrasound examination was performed in all women and afterwards they underwent laparoscopy to identify the source of bleeding. In all cases a ruptured endometriotic cyst was found. In 68.8% (11/16) the ruptured cyst was located in the left ovary and the rest (31.2%) in the right. A thorough examination did not reveal any other sources of bleeding. No operative complications were observed.

DISCUSSION

The simultaneous occurrence of ascites and endometriosis is rare. A physician, though, must always take into consideration endometriosis in the differential diagnosis of ascites and acute abdominal pain or pelvic mass.

Ovarian endometriosis associated with ovarian cancer and endometrial-endocervical polyps

AIM

To determine the prevalence of ovarian cancer and endometrial polyps in women with moderate and severe ovarian endometriosis.

METHODS

A retrospective analysis of 667 cases of moderate and severe endometriosis laparoscopically and histologically confirmed during the period 1997-2004.

RESULTS

One hundred and ninety-three (29%) of cases were American Fertility Society (AFS) stage III (moderate endometriosis) and 473 (71%) were AFS stage IV (severe endometriosis). Ovarian cancer was diagnosed in 13 cases (2.0%), while an endometrial or endocervical polyp was identified in 35 cases (5.3%). The incidence of endometrial polyps in the group with moderate endometriosis tended to be higher (15/193, 7.8%) than in the group with severe endometriosis (20/473, 4.2%), and the same results were obtained in the ovarian cancer group (moderate: 6/193, 3.1%; severe: 7/473, 1.5%). However, neither of the two differences was statistically significant.

CONCLUSIONS

Ovarian endometriosis may be associated with an increased incidence of both ovarian cancer and endometrial polyps. Careful evaluation for coexistent pathology should be undertaken in women with symptomatic endometriosis.

Constitutive activation of JAK3/STAT3 in colon carcinoma tumors and cell lines: inhibition of JAK3/STAT3 signaling induces apoptosis and cell cycle arrest of colon carcinoma cells

Signal transducer and activator of transcription 3 (STAT3) has oncogenic potential. The biological effects of STAT3 have not been studied extensively in the pathogenesis of colon cancer, nor has the role of Janus kinase 3 (JAK3), the physiological activator of STAT3, been evaluated. Here, we demonstrate that activated STAT3 (pSTAT3) and activated JAK3 (pJAK3) are expressed constitutively in two colon cancer cell lines, SW480 and HT29. To evaluate the significance of JAK3/STAT3 signaling, we inhibited JAK3 with AG490 and STAT3 with a dominant-negative construct. Inhibition of JAK3 down-regulated pSTAT3. The blockade of JAK3/STAT3 signaling significantly decreased viability of colon cancer cells due to apoptosis and cell-cycle arrest through down-regulation of Bcl-2, Bcl-X(L), Mcl-1, and cyclin D2 and up-regulation of p21(waf1/cip1) and p27(kip1). We also examined histological sections from 22 tumors from patients with stage II or stage IV colon cancer and found STAT3, JAK3, and their activated forms to be frequently expressed. Furthermore, quantitative reverse transcriptase-polymerase chain reaction identified JAK3 mRNA in colon cancer cell lines and primary tumors. Our findings illustrate the biological importance of JAK3/STAT3 activation in the oncogenesis of colon cancer and provide novel evidence that JAK3 is expressed and contributes to STAT3 activation in this malignant neoplasm.

Inhibition of Akt increases p27Kip1 levels and induces cell cycle arrest in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a highly proliferative neoplasm that frequently carries the t(2;5)(p23;q35) and aberrantly expresses nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). Previously, NPM-ALK had been shown to activate the phosphatidylinositol 3 kinase (PI3K)/Akt pathway. As the cyclin-dependent kinase (CDK) inhibitor p27(Kip1) (p27) is usually not expressed in ALCL, we hypothesized that activated Akt (pAkt) phosphorylates p27 resulting in increased p27 proteolysis and cell cycle progression. Here we demonstrate that inhibition of pAkt activity in ALCL decreases p27 phosphorylation and degradation, resulting in increased p27 levels and cell cycle arrest. Using immunohistochemistry, pAkt was detected in 24 (57%) of 42 ALCL tumors, including 8 (44%) of 18 ALK-positive tumors and 16 (67%) of 24 ALK-negative tumors, and was inversely correlated with p27 levels. The mean percentage of p27-positive tumor cells was 5% in the pAkt-positive group compared with 26% in the pAkt-negative group (P = .0076). These findings implicate that Akt activation promotes cell cycle progression through inactivation of p27 in ALCL.