Modulation of mismatch repair and genomic stability by miR-155

MicroRNAs Used in Combination with Anti-Cancer Treatments Can Enhance Therapy Efficacy

MicroRNAs (miRNAs), a recently discovered class of small non-coding RNAs, constitute a promising approach to anti-cancer treatments when they are used in combination with other agents. MiRNAs are evolutionarily conserved non-coding RNAs that negatively regulate gene expression by binding to the complementary sequence in the 3'-untranslated region (UTR) of target genes. MiRNAs typically suppress gene expression by direct association with target transcripts, thus decreasing the expression levels of target proteins. The delivery to cells of synthetic miRNAs that mimic endogenous miRNA targeting genes involved in the DNA-Damage Response (DDR) can perturb the process, making cells more sensitive to chemotherapy or radiotherapy. This review examines how cells respond to combined therapy and it provides insights into the role of miRNAs in targeting the DDR repair pathway when they are used in combination with chemical compounds or ionizing radiation to enhance cellular sensitivity to treatments.

Hereditary Colorectal Cancer in China: Current Status and Progress

<b><i>Background:</i></b> Hereditary colorectal cancer (CRC) accounts for about 5% of the total incidence of CRC. During the last decades, there have been great advances in the research of hereditary CRC in China. <b><i>Summary:</i></b> This review mainly focuses on advances of the genetic basis, clinicopathological features, diagnosis, chemoprevention and treatment of hereditary CRC in China. <b><i>Key Message:</i></b> Hereditary CRC has a higher risk to initiate the progression towards neoplasia than sporadic CRC. It can be diagnosed by clinical manifestation or the relevant genetic testing so as to guide the clinical treatment to improve the survival rate and survival quality of patients. <b><i>Practical Implications:</i></b> Hereditary CRC includes hereditary nonpolyposis CRC (Lynch syndrome), familial adenomatous polyposis and other rare types such as Peutz-Jeghers syndrome and familial juvenile polyposis. Based on the clinical manifestations and family history, highly suspected cases can be screened for in the general population and the diagnosis ruled out by genetic analysis. Then, chemoprevention, endoscopic intervention or surgery can be selected properly to improve patients' survival and quality of life.

MicroRNAs in colorectal cancer: small molecules with big functions

Colorectal cancer (CRC) is the third most lethal malignancy, with pathogenesis intricately dependent upon microRNAs (miRNAs). miRNAs are short, non-protein coding RNAs, targeting the 3'-untranslated regions (3'-UTR) of certain mRNAs. They usually serve as tumor suppressors or oncogenes, and participate in tumor phenotype maintenance. Therefore, miRNAs consequently regulate CRC carcinogenesis and other biological functions, including apoptosis, development, angiogenesis, migration, and proliferation. Due to its differential expression and distinct stability, miRNAs are regarded as molecular biomarkers (for diagnosis/prognosis) and therapeutic targets for CRC. Recently, a remarkable number of miRNAs have been discovered with implications via incompletely understood mechanisms in CRC. As further study of relevant miRNAs continues, it is hopeful that novel miRNA-based therapeutic strategies may be available for CRC patients in the future.

Pathophysiology of ocular surface squamous neoplasia

The incidence of ocular surface squamous neoplasia (OSSN) is strongly associated with solar ultraviolet (UV) radiation, HIV and human papilloma virus (HPV). Africa has the highest incidence rates in the world. Most lesions occur at the limbus within the interpalpebral fissure particularly the nasal sector. The nasal limbus receives the highest intensity of sunlight. Limbal epithelial crypts are concentrated nasally and contain niches of limbal epithelial stem cells in the basal layer. It is possible that these are the progenitor cells in OSSN. OSSN arises in the basal epithelial cells spreading towards the surface which resembles the movement of corneo-limbal stem cell progeny before it later invades through the basement membrane below. UV radiation damages DNA producing pyrimidine dimers in the DNA chain. Specific CC → TT base pair dimer transformations of the p53 tumour-suppressor gene occur in OSSN allowing cells with damaged DNA past the G1-S cell cycle checkpoint. UV radiation also causes local and systemic photoimmunosuppression and reactivates latent viruses such as HPV. The E7 proteins of HPV promote proliferation of infected epithelial cells via the retinoblastoma gene while E6 proteins prevent the p53 tumour suppressor gene from effecting cell-cycle arrest of DNA-damaged and infected cells. Immunosuppression from UV radiation, HIV and vitamin A deficiency impairs tumour immune surveillance allowing survival of aberrant cells. Tumour growth and metastases are enhanced by; telomerase reactivation which increases the number of cell divisions a cell can undergo; vascular endothelial growth factor for angiogenesis and matrix metalloproteinases (MMPs) that destroy the intercellular matrix between cells. Despite these potential triggers, the disease is usually unilateral. It is unclear how HPV reaches the conjunctiva.

Pathogenic microRNA's in myeloid malignancies

Recent studies have significantly improved our understanding of the role microRNAs (miRNAs) play in regulating normal hematopoiesis. miRNAs are critical for maintaining hematopoietic stem cell function and the development of mature progeny. Thus, perhaps it is not surprising that miRNAs serve as oncogenes and tumor suppressors in hematologic malignancies arising from hematopoietic stem and progenitor cells, such as the myeloid disorders. A number of studies have extensively documented the widespread dysregulation of miRNA expression in human acute myeloid leukemia (AML), inspiring numerous explorations of the functional role of miRNAs in myeloid leukemogenesis. While these investigations have confirmed that a large number of miRNAs exhibit altered expression in AML, only a small fraction has been confirmed as functional mediators of AML development or maintenance. Herein, we summarize the miRNAs for which strong experimental evidence supports their functional roles in AML pathogenesis. We also discuss the implications of these studies on the development of miRNA-directed therapies in AML.

Clinical problems of colorectal cancer and endometrial cancer cases with unknown cause of tumor mismatch repair deficiency (suspected Lynch syndrome)

Carriers of a germline mutation in one of the DNA mismatch repair (MMR) genes have a high risk of developing numerous different cancers, predominantly colorectal cancer and endometrial cancer (known as Lynch syndrome). MMR gene mutation carriers develop tumors with MMR deficiency identified by tumor microsatellite instability or immunohistochemical loss of MMR protein expression. Tumor MMR deficiency is used to identify individuals most likely to carry an MMR gene mutation. However, MMR deficiency can also result from somatic inactivation, most commonly methylation of the MLH1 gene promoter. As tumor MMR testing of all incident colorectal and endometrial cancers (universal screening) is becoming increasingly adopted, a growing clinical problem is emerging for individuals who have tumors that show MMR deficiency who are subsequently found not to carry an MMR gene mutation after genetic testing using the current diagnostic approaches (Sanger sequencing and multiplex ligation-dependent probe amplification) and who also show no evidence of MLH1 methylation. The inability to determine the underlying cause of tumor MMR deficiency in these “Lynch-like” or “suspected Lynch syndrome” cases has significant implications on the clinical management of these individuals and their relatives. When the data from published studies are combined, 59% (95% confidence interval [CI]: 55% to 64%) of colorectal cancers and 52% (95% CI: 41% to 62%) of endometrial cancers with MMR deficiency were identified as suspected Lynch syndrome. Recent studies estimated that colorectal cancer risk for relatives of suspected Lynch syndrome cases is lower than for relatives of those with MMR gene mutations, but higher than for relatives of those with tumor MMR deficiency resulting from methylation of the MLH1 gene promoter. The cause of tumor MMR deficiency in suspected Lynch syndrome cases is likely due to either unidentified germline MMR gene mutations, somatic cell mosaicism, or biallelic somatic inactivation. Determining the underlying cause of tumor MMR deficiency in suspected Lynch syndrome cases is likely to reshape the current triaging schemes used to identify germline MMR gene mutations in cancer-affected individuals and their relatives.

The evolution of colorectal cancer genetics-Part 1: from discovery to practice

Colorectal cancer (CRC) is an increasing burden on our society. Identifying those who are at the greatest risk and improving triage for treatment will have the greatest impact on healthcare. CRC is a prime paradigm for cancer genetics: the majority of disease results from stages of progression lending itself to prevention by early detection of the pre-disease (neoplastic) state. Approximately 10% represent well defined hereditary cancer syndromes. Hereditary CRC has the added benefit that many are slow growing and family members are armed with the knowledge of potential risk of associated carcinomas and empowerment to reduce the disease burden. This knowledge provides the indication for early endoscopic and/or surgical intervention for prevention or treatment of an entire family cohort. The molecular basis of CRC allows enhanced characterization of carcinomas, leading to targeted therapies.

Key principles of miRNA involvement in human diseases

Although rapid progress in our understanding of the functions of miRNA has been made by experimentation and computational approach, a considerable effort still has to be done in determining the general principles that govern the miRNA's mode of action in human diseases. We will further discuss how these principles are being progressively approached by molecular studies, as well as the importance of miRNA in regulating different target genes and functions in specific biological contexts. There is a great demand to understand the principles of context - specific miRNA target recognition in order to design future experiments and models of normal developmental and disease states.

Targeting the microRNA-regulating DNA damage/repair pathways in cancer

INTRODUCTION

Maintenance of genome stability requires the integrity of the DNA repair machinery. DNA damage response (DDR) determines cell fate and regulates the expression of microRNAs (miRNAs), which in turn may also regulate important components of the DNA repair machinery.

AREAS COVERED

In this review, we describe the bidirectional connection between miRNAs and DDR and their link with important biological functions such as, DNA repair, cell cycle and apoptosis in cancer. Furthermore, we highlight the potential implications of recent findings on miRNA/DDR in determining chemotherapy response in cancer patients, and the use of these biomarkers for novel potential therapeutic approaches.

EXPERT OPINION

Defects in the DDR and deregulation of miRNAs are important hallmarks of human cancer. A full understanding of the mechanisms underlying the connection between miRNAs and DDR/DNA repair pathways will positively impact our knowledge on human tumor biology and on different responses to distinct drugs. Specific miRNAs interact with distinct DDR components and are promising targets for enhancing the effects of, and/or to overcome the resistance to, conventional chemotherapeutic agents. Finally, the development of innovative tools to deliver miRNA-targeting oligonucleotides may represents novel types of cancer interventions in clinic.

MicroRNAs, genomic instability and cancer

MicroRNAs (miRNAs) are small non-coding RNA transcripts approximately 20 nucleotides in length that regulate expression of protein-coding genes via complementary binding mechanisms. The last decade has seen an exponential increase of publications on miRNAs, ranging from every aspect of basic cancer biology to diagnostic and therapeutic explorations. In this review, we summarize findings of miRNA involvement in genomic instability, an interesting but largely neglected topic to date. We discuss the potential mechanisms by which miRNAs induce genomic instability, considered to be one of the most important driving forces of cancer initiation and progression, though its precise mechanisms remain elusive. We classify genomic instability mechanisms into defects in cell cycle regulation, DNA damage response, and mitotic separation, and review the findings demonstrating the participation of specific miRNAs in such mechanisms.

Novel diet-related mouse model of colon cancer parallels human colon cancer

AIM: To investigate the close parallels between our novel diet-related mouse model of colon cancer and human colon cancer.

METHODS: Twenty-two wild-type female mice (ages 6-8 wk) were fed the standard control diet (AIN-93G) and an additional 22 female mice (ages 6-8 wk) were fed the control diet supplemented with 0.2% deoxycholic acid [diet + deoxycholic acid (DOC)] for 10 mo. Tumors occurred in the colons of mice fed diet + DOC and showed progression to colon cancer [adenocarcinoma (AC)]. This progression is through the stages of tubular adenoma (TA), TA with high grade dysplasia or adenoma with sessile serrated morphology, intramucosal AC, AC stage T1, and AC stage T2. The mouse tumors were compared to human tumors at the same stages by histopathological analysis. Sections of the small and large intestines of mice and humans were evaluated for glandular architecture, cellular and nuclear morphology including cellular orientation, cellular and nuclear atypia, pleomorphism, mitotic activity, frequency of goblet cells, crypt architecture, ulceration, penetration of crypts through the muscularis mucosa and presence of malignant crypts in the muscularis propria. In addition, preserved colonic tissues from genetically similar male mice, obtained from a prior experiment, were analyzed by immunohistochemistry. The male mice had been fed the control diet or diet + DOC. Four molecular markers were evaluated: 8-OH-dG, DNA repair protein ERCC1, autophagy protein beclin-1 and the nuclear location of beta-catenin in the stem cell region of crypts. Also, male mice fed diet + DOC plus 0.007% chlorogenic acid (diet + DOC + CGA) were evaluated for ERCC1, beclin-1 and nuclear location of beta-catenin.

RESULTS: Humans with high levels of diet-related DOC in their colons are at a substantially increased risk of developing colon cancer. The mice fed diet + DOC had levels of DOC in their colons comparable to that of humans on a high fat diet. The 22 mice without added DOC in their diet had no colonic tumors while 20 of the 22 mice (91%) fed diet + DOC developed colonic tumors. Furthermore, the tumors in 10 of these mice (45% of mice) included an adenocarcinoma. All mice were free of cancers of the small intestine. Histopathologically, the colonic tumor types in the mice were virtually identical to those in humans. In humans, characteristic aberrant changes in molecular markers can be detected both in field defects surrounding cancers (from which cancers arise) and within cancers. In the colonic tissues of mice fed diet + DOC similar changes in biomarkers appeared to occur. Thus, 8-OH-dG was increased, DNA repair protein ERCC1 was decreased, autophagy protein beclin-1 was increased and, in the stem cell region at the base of crypts there was substantial nuclear localization of beta-catenin as well as increased cytoplasmic beta-catenin. However, in mice fed diet + DOC + CGA (with reduced frequency of cancer) and evaluated for ERCC1, beclin-1, and beta-catenin in the stem cell region of crypts, mouse tissue showed amelioration of the aberrancies, suggesting that chlorogenic acid is protective at the molecular level against colon cancer. This is the first diet-related model of colon cancer that closely parallels human progression to colon cancer, both at the histomorphological level as well as in its molecular profile.

CONCLUSION: The diet-related mouse model of colon cancer parallels progression to colon cancer in humans, and should be uniquely useful in model studies of prevention and therapeutics.

MicroRNAs: short non-coding players in cancer chemoresistance

Chemoresistance is one of the main problems in the therapy of cancer. There are a number of different molecular mechanisms through which a cancer cell acquires resistance to a specific treatment, such as alterations in drug uptake, drug metabolism and drug targets. There are several lines of evidence showing that miRNAs are involved in drug sensitivity of cancer cells in different tumor types and by different treatments. In this review, we provide an overview of the more recent and significant findings on the role of miRNAs in cancer cell drug resistance. In particular, we focus on specific miRNA mechanisms of action that in various steps lead from drug cell sensitivity to drug cell resistance. We also provide evidence on how miRNA profiling may unveil relevant predictive biomarkers for therapy outcomes.

MicroRNAs: short non-coding players in cancer chemoresistance

Chemoresistance is one of the main problems in the therapy of cancer. There are a number of different molecular mechanisms through which a cancer cell acquires resistance to a specific treatment, such as alterations in drug uptake, drug metabolism and drug targets. There are several lines of evidence showing that miRNAs are involved in drug sensitivity of cancer cells in different tumor types and by different treatments. In this review, we provide an overview of the more recent and significant findings on the role of miRNAs in cancer cell drug resistance. In particular, we focus on specific miRNA mechanisms of action that in various steps lead from drug cell sensitivity to drug cell resistance. We also provide evidence on how miRNA profiling may unveil relevant predictive biomarkers for therapy outcomes.

miR-155 drives telomere fragility in human breast cancer by targeting TRF1

Telomeres consist of DNA tandem repeats that recruit the multiprotein complex shelterin to build a chromatin structure that protects chromosome ends. Although cancer formation is linked to alterations in telomere homeostasis, there is little understanding of how shelterin function is limited in cancer cells. Using a small-scale screening approach, we identified miR-155 as a key regulator in breast cancer cell expression of the shelterin component TERF1 (TRF1). miR-155 targeted a conserved sequence motif in the 3'UTR of TRF1, resulting in its translational repression. miR-155 was upregulated commonly in breast cancer specimens, as associated with reduced TRF1 protein expression, metastasis-free survival, and relapse-free survival in estrogen receptor-positive cases. Modulating miR-155 expression in cells altered TRF1 levels and TRF1 abundance at telomeres. Compromising TRF1 expression by elevating miR-155 increased telomere fragility and altered the structure of metaphase chromosomes. In contrast, reducing miR-155 levels improved telomere function and genomic stability. These results implied that miR-155 upregulation antagonizes telomere integrity in breast cancer cells, increasing genomic instability linked to poor clinical outcome in estrogen receptor-positive disease. Our work argued that miRNA-dependent regulation of shelterin function has a clinically significant impact on telomere function, suggesting the existence of "telo-miRNAs" that have an impact on cancer and aging.

MicroRNA-135b promotes cancer progression by acting as a downstream effector of oncogenic pathways in colon cancer

MicroRNA deregulation is frequent in human colorectal cancers (CRCs), but little is known as to whether it represents a bystander event or actually drives tumor progression in vivo. We show that miR-135b overexpression is triggered in mice and humans by APC loss, PTEN/PI3K pathway deregulation, and SRC overexpression and promotes tumor transformation and progression. We show that miR-135b upregulation is common in sporadic and inflammatory bowel disease-associated human CRCs and correlates with tumor stage and poor clinical outcome. Inhibition of miR-135b in CRC mouse models reduces tumor growth by controlling genes involved in proliferation, invasion, and apoptosis. We identify miR-135b as a key downsteam effector of oncogenic pathways and a potential target for CRC treatment.

Protective role of miR-155 in breast cancer through RAD51 targeting impairs homologous recombination after irradiation

Cell survival after DNA damage relies on DNA repair, the abrogation of which causes genomic instability and development of cancer. However, defective DNA repair in cancer cells can be exploited for cancer therapy using DNA-damaging agents. DNA double-strand breaks are the major lethal lesions induced by ionizing radiation (IR) and can be efficiently repaired by DNA homologous recombination, a system that requires numerous factors including the recombinase RAD51 (RAD51). Therapies combined with adjuvant radiotherapy have been demonstrated to improve the survival of triple-negative breast cancer patients; however, such therapy is challenged by the emergence of resistance in tumor cells. It is, therefore, essential to develop novel therapeutic strategies to overcome radioresistance and improve radiosensitivity. In this study we show that overexpression of microRNA 155 (miR-155) in human breast cancer cells reduces the levels of RAD51 and affects the cellular response to IR. miR-155 directly targets the 3'-untranslated region of RAD51. Overexpression of miR-155 decreased the efficiency of homologous recombination repair and enhanced sensitivity to IR in vitro and in vivo. High miR-155 levels were associated with lower RAD51 expression and with better overall survival of patients in a large series of triple-negative breast cancers. Taken together, our findings indicate that miR-155 regulates DNA repair activity and sensitivity to IR by repressing RAD51 in breast cancer. Testing for expression levels of miR-155 may be useful in the identification of breast cancer patients who will benefit from an IR-based therapeutic approach.

Role of virus-encoded microRNAs in Avian viral diseases

With total dependence on the host cell, several viruses have adopted strategies to modulate the host cellular environment, including the modulation of microRNA (miRNA) pathway through virus-encoded miRNAs. Several avian viruses, mostly herpesviruses, have been shown to encode a number of novel miRNAs. These include the highly oncogenic Marek’s disease virus-1 (26 miRNAs), avirulent Marek’s disease virus-2 (36 miRNAs), herpesvirus of turkeys (28 miRNAs), infectious laryngotracheitis virus (10 miRNAs), duck enteritis virus (33 miRNAs) and avian leukosis virus (2 miRNAs). Despite the closer antigenic and phylogenetic relationship among some of the herpesviruses, miRNAs encoded by different viruses showed no sequence conservation, although locations of some of the miRNAs were conserved within the repeat regions of the genomes. However, some of the virus-encoded miRNAs showed significant sequence homology with host miRNAs demonstrating their ability to serve as functional orthologs. For example, mdv1-miR-M4-5p, a functional ortholog of gga-miR-155, is critical for the oncogenicity of Marek’s disease virus. Additionally, we also describe the potential association of the recently described avian leukosis virus subgroup J encoded E (XSR) miRNA in the induction of myeloid tumors in certain genetically-distinct chicken lines. In this review, we describe the advances in our understanding on the role of virus-encoded miRNAs in avian diseases.

microRNA expression profiling identifies a four microRNA signature as a novel diagnostic and prognostic biomarker in triple negative breast cancers

Triple Negative Breast Cancers (TNBC) is a heterogeneous disease at the molecular and clinical level with poor outcome. Molecular subclassification of TNBCs is essential for optimal use of current therapies and for development of new drugs. microRNAs (miRNA) are widely recognized as key players in cancer progression and drug resistance; investigation of their involvement in a TNBC cohort may reveal biomarkers for diagnosis and prognosis of TNBC. Here we stratified a large TNBC cohort into Core Basal (CB, EGFR and/or CK5, 6 positive) and five negative (5NP) if all markers are negative. We determined the complete miRNA expression profile and found a subset of miRNAs specifically deregulated in the two subclasses.We identified a 4-miRNA signature given by miR-155, miR-493, miR-30e and miR-27a expression levels, that allowed subdivision of TNBCs not only into CB and 5NP subgroups (sensitivity 0.75 and specificity 0.56; AUC=0.74) but also into high risk and low risk groups. We tested the diagnostic and prognostic performances of both the 5 IHC marker panel and the 4-miRNA expression signatures, which clearly identify worse outcome patients in the treated and untreated subcohorts. Both signatures have diagnostic and prognostic value, predicting outcomes of patient treatment with the two most commonly used chemotherapy regimens in TNBC: anthracycline or anthracycline plus taxanes. Further investigations of the patients’ overall survival treated with these regimens show that regardless of IHC group subdivision, taxanes addition did not benefit patients, possibly due to miRNA driven taxanes resistance. TNBC subclassification based on the 5 IHC markers and on the miR-155, miR-493, miR-30e, miR-27a expression levels are powerful diagnostic tools. Treatment choice and new drug development should consider this new subtyping and miRNA expression signature in planning low toxicity, maximum efficacy therapies.

Noncoding RNAs in DNA repair and genome integrity

SIGNIFICANCE

The well-studied sequences in the human genome are those of protein-coding genes, which account for only 1%-2% of the total genome. However, with the advent of high-throughput transcriptome sequencing technology, we now know that about 90% of our genome is extensively transcribed and that the vast majority of them are transcribed into noncoding RNAs (ncRNAs). It is of great interest and importance to decipher the functions of these ncRNAs in humans.

RECENT ADVANCES

In the last decade, it has become apparent that ncRNAs play a crucial role in regulating gene expression in normal development, in stress responses to internal and environmental stimuli, and in human diseases.

CRITICAL ISSUES

In addition to those constitutively expressed structural RNA, such as ribosomal and transfer RNAs, regulatory ncRNAs can be classified as microRNAs (miRNAs), Piwi-interacting RNAs (piRNAs), small interfering RNAs (siRNAs), small nucleolar RNAs (snoRNAs), and long noncoding RNAs (lncRNAs). However, little is known about the biological features and functional roles of these ncRNAs in DNA repair and genome instability, although a number of miRNAs and lncRNAs are regulated in the DNA damage response.

FUTURE DIRECTIONS

A major goal of modern biology is to identify and characterize the full profile of ncRNAs with regard to normal physiological functions and roles in human disorders. Clinically relevant ncRNAs will also be evaluated and targeted in therapeutic applications.

MicroRNAs in the DNA Damage/Repair Network and Cancer

Cancer is a multistep process characterized by various and different genetic lesions which cause the transformation of normal cells into tumor cells. To preserve the genomic integrity, eukaryotic cells need a complex DNA damage/repair response network of signaling pathways, involving many proteins, able to induce cell cycle arrest, apoptosis, or DNA repair. Chemotherapy and/or radiation therapy are the most commonly used therapeutic approaches to manage cancer and act mainly through the induction of DNA damage. Impairment in the DNA repair proteins, which physiologically protect cells from persistent DNA injury, can affect the efficacy of cancer therapies. Recently, increasing evidence has suggested that microRNAs take actively part in the regulation of the DNA damage/repair network. MicroRNAs are endogenous short noncoding molecules able to regulate gene expression at the post-transcriptional level. Due to their activity, microRNAs play a role in many fundamental physiological and pathological processes. In this review we report and discuss the role of microRNAs in the DNA damage/repair and cancer.

Interplay between DNA repair and inflammation, and the link to cancer

DNA damage and repair are linked to cancer. DNA damage that is induced endogenously or from exogenous sources has the potential to result in mutations and genomic instability if not properly repaired, eventually leading to cancer. Inflammation is also linked to cancer. Reactive oxygen and nitrogen species (RONs) produced by inflammatory cells at sites of infection can induce DNA damage. RONs can also amplify inflammatory responses, leading to increased DNA damage. Here, we focus on the links between DNA damage, repair, and inflammation, as they relate to cancer. We examine the interplay between chronic inflammation, DNA damage and repair and review recent findings in this rapidly emerging field, including the links between DNA damage and the innate immune system, and the roles of inflammation in altering the microbiome, which subsequently leads to the induction of DNA damage in the colon. Mouse models of defective DNA repair and inflammatory control are extensively reviewed, including treatment of mouse models with pathogens, which leads to DNA damage. The roles of microRNAs in regulating inflammation and DNA repair are discussed. Importantly, DNA repair and inflammation are linked in many important ways, and in some cases balance each other to maintain homeostasis. The failure to repair DNA damage or to control inflammatory responses has the potential to lead to cancer.

Hypoxia and DNA repair

Hypoxia is a characteristic feature of solid tumors and occurs very early in neoplastic development. Hypoxia transforms cell physiology in multiple ways, with profound changes in cell metabolism, cell growth, susceptibility to apoptosis, induction of angiogenesis, and increased motility. Over the past 20 years, our lab has determined that hypoxia also induces genetic instability. We have conducted a large series of experiments revealing that this instability occurs through the alteration of DNA repair pathways, including nucleotide excision repair, DNA mismatch repair, and homology dependent repair. Our work suggests that hypoxia, as a key component of solid tumors, can drive cancer progression through its impact on genomic integrity. However, the acquired changes in DNA repair that are induced by hypoxia may also render hypoxic cancer cells vulnerable to tailored strategies designed to exploit these changes.

Therapeutic evaluation of microRNAs by molecular imaging

MicroRNAs (miRNAs) function as regulatory molecules of gene expression with multifaceted activities that exhibit direct or indirect oncogenic properties, which promote cell proliferation, differentiation, and the development of different types of cancers. Because of their extensive functional involvement in many cellular processes, under both normal and pathological conditions such as various cancers, this class of molecules holds particular interest for cancer research. MiRNAs possess the ability to act as tumor suppressors or oncogenes by regulating the expression of different apoptotic proteins, kinases, oncogenes, and other molecular mechanisms that can cause the onset of tumor development. In contrast to current cancer medicines, miRNA-based therapies function by subtle repression of gene expression on a large number of oncogenic factors, and therefore are anticipated to be highly efficacious. Given their unique mechanism of action, miRNAs are likely to yield a new class of targeted therapeutics for a variety of cancers. More than thousand miRNAs have been identified to date, and their molecular mechanisms and functions are well studied. Furthermore, they are established as compelling therapeutic targets in a variety of cellular complications. However, the notion of using them as therapeutic tool was proposed only recently, given that modern imaging methods are just beginning to be deployed for miRNA research. In this review, we present a summary of various molecular imaging methods, which are instrumental in revealing the therapeutic potential of miRNAs, especially in various cancers. Imaging methods have recently been developed for monitoring the expression levels of miRNAs and their target genes by fluorescence-, bioluminescence- and chemiluminescence-based imaging techniques. Mature miRNAs bind to the untranslated regions (UTRs) of the target mRNAs and regulate target genes expressions. This concept has been used for the development of fluorescent reporter-based imaging strategies to monitor the functional status of endogenous miRNAs, or the respective miRNAs transiently co-expressed in cells. Bioluminescence-based imaging strategies have been used to investigate various stages of miRNA processing and its involvement in different cellular processes. Similarly, chemiluminsecence methods were developed for in vitro miRNA imaging such as monitoring their therapeutic roles in various cancer cell lines.

microRNA-100 targets SMRT/NCOR2, reduces proliferation, and improves survival in glioblastoma animal models

Glioblastoma (GBM) is the most frequently diagnosed malignant human glioma, and current median patient survival is less than two years despite maximal surgery followed by temozolomide chemoradiation therapies. Novel microRNA-related therapies are now being developed for cancers such as GBM. Differential microRNA expression profiling revealed that miR-100 expression is down-regulated in GBM compared to normal controls. We report that miR-100 expression reduces GBM tumorigenicity. In vitro, four GBM lines (U87, U251, 22T, and 33T) demonstrated reduced proliferation 24 hours after transient miR100 overexpression via transfection. miR-100 triggered cell death an average 70% more than scrambled miR controls 24 hours after transient transfection (p < 0.01). miR-100 targeted inhibition of the “silencing mediator of retinoid or thyroid hormone receptor-2” (SMRT/NCOR2) gene was confirmed via reporter assays. Ki67 proliferation index was decreased 40% in tumor xenografts generated from stable miR-100 transfected GBM lines versus controls (p < 0.01). Furthermore, treatment of tumor xenografts with a single pre-mir-100 injection (60 pmol) significantly extended survival of mice bearing intracranial GBM xenografts 25% more than scrambled controls (p < 0.01; n=8). These studies establish miR-100’s effect on tumor GBM growth, and suggest clinical potential for microRNA-related GBM therapy.

Multispectral Imaging

The field of anatomic pathology has changed significantly over the last decades and, as a result of the technological developments in molecular pathology and genetics, has had increasing pressures put on it to become quantitative and to provide more information about protein expression on a cellular level in tissue sections. Multispectral imaging (MSI) has a long history as an advanced imaging modality and has been used for over a decade now in pathology to improve quantitative accuracy, enable the analysis of multicolor immunohistochemistry, and drastically reduce the impact of contrast-robbing tissue autofluorescence common in formalin-fixed, paraffin-embedded tissues. When combined with advanced software for the automated segmentation of different tissue morphologies (eg, tumor vs stroma) and cellular and subcellular segmentation, MSI can enable the per-cell quantitation of many markers simultaneously. This article covers the role that MSI has played in anatomic pathology in the analysis of formalin-fixed, paraffin-embedded tissue sections, discusses the technological aspects of why MSI has been adopted, and provides a review of the literature of the application of MSI in anatomic pathology.

Regulation of B-cell development and function by microRNAs

MicroRNAs (miRNAs) have emerged as a new class of gene expression regulators whose functions influence a myriad of biological processes, from developmental decisions through immune responses and numerous pathologies, including cancer and autoimmunity. miRNAs are small RNA molecules that drive post-transcriptional negative regulation of gene expression by promoting the degradation or translational block of their target mRNAs. Here, we review some of the data relating to the role of miRNAs in the regulation of the B-cell lineage, with a special focus on results obtained in vivo. We start by giving a general overview of miRNA activity, including the issue of target specificity and the experimental approaches more widely used to analyze the function of these molecules. We then go on to discuss the function of miRNAs during B-cell differentiation in the bone marrow and in the periphery as well as during the humoral immune response. Finally, we describe a few examples of the contribution of miRNAs, both as oncogenes and tumor suppressors, to the development of B-cell neoplasias.

How microRNAs influence both hereditary and inflammatory-mediated colon cancers

MicroRNAs have emerged as important post-translational regulators of gene expression and are involved in several physiological and pathological states including the pathogenesis of human colon cancers. In regards to tumor development, microRNAs can act as oncogenes or tumor suppressors. Two hereditary predispositions (i.e., Lynch syndrome and familial adenomatous polyposis) contribute to the development of colon cancer. In addition, individuals who suffer from inflammatory bowel diseases such as Crohn's disease or ulcerative colitis have a higher risk of developing colon cancer. Here, we discuss the occurrence of the deregulated expression of microRNAs in colon cancer that arise as a result of hereditary predisposition and inflammatory bowel disease.

miR-153 supports colorectal cancer progression via pleiotropic effects that enhance invasion and chemotherapeutic resistance

Although microRNAs (miRNA) have been broadly studied in cancer, comparatively less is understood about their role in progression. Here we report that miR-153 has a dual role during progression of colorectal cancer by enhancing cellular invasiveness and platinum-based chemotherapy resistance. miRNA profiling revealed that miR-153 was highly expressed in a cellular model of advanced stage colorectal cancer. Its upregulation was also noted in primary human colorectal cancer compared with normal colonic epithelium and in more advanced colorectal cancer stages compared with early stage disease. In colorectal cancer patients followed for 50 months, 21 of 30 patients with high levels of miR-153 had disease progression compared with others in this group with low levels of miR-153. Functional studies revealed that miR-153 upregulation increased colorectal cancer invasiveness and resistance to oxaliplatin and cisplatin both in vitro and in vivo. Mechanistic investigations indicated that miR-153 promoted invasiveness indirectly by inducing matrix metalloprotease enzyme 9 production, whereas drug resistance was mediated directly by inhibiting the Forkhead transcription factor Forkhead box O3a (FOXO3a). In support of the latter finding, we found that levels of miR-153 and FOXO3a were inversely correlated in matched human colorectal cancer specimens. Our findings establish key roles for miR-153 overexpression in colorectal cancer progression, rationalizing therapeutic strategies to target expression of this miRNA for colorectal cancer treatment.

MLH1 as a direct target of MiR-155 and a potential predictor of favorable prognosis in pancreatic cancer

BACKGROUND

The regulation of Mut L homologue 1 (MLH1) expression by microRNA (miR)-155 and its prognostic significance in pancreatic cancer (PC) remain to be elucidated. This study aimed to address the issues.

METHODS

MiR-155 mimics and inhibitor were transfected to PC cell lines, Panc-1 and Capan-1. Expression of MLH1 was subsequently evaluated. Then, luciferase activity was detected after miR-155 mimics and pRL-TK plasmids containing wild-type and mutant 3'UTRs of MLH1 mRNA were co-transfected. Finally, immunohistochemical staining for MLH1 was performed in PC samples.

RESULTS

Transfection of miR-155 mimics and inhibitor led to reversely altered protein expressions of miR-155 and MLH1, whereas the corresponding mRNA expressions were similar. A significant decrease in luciferase activity in the cells transfected with the wild-type pRL-TK plasmid was shown in contrast to those transfected with the mutant one. In addition, MLH1 was less expressed in tumor than in para-tumor tissues of PC. Extensive MLH1 expression was significantly associated with favorable differentiation and less lymph node metastasis. MLH1 expression was found to be a prognosticator in univariate analysis, and being of marginally significant impact in multivariate test.

CONCLUSIONS

MLH1 might serve as a direct target of miR-155 and a potential prognosis predictor in PC.

Pleiotropic actions of miR-21 highlight the critical role of deregulated stromal microRNAs during colorectal cancer progression

The oncogene microRNA-21 (miRNA; miR-21) is overexpressed in most solid organ tumours; however, a recent examination of stage II colorectal cancer (CRC) specimens suggests this may be a stromal phenomenon and not only a feature of cancer cells. In vitro and in vivo studies show that miR-21 has potent pro-metastatic effects in various malignant carcinoma cell lines. The tumour microenvironment has also been identified as a key actor during the metastatic cascade; however to date the significance of deregulated miR-21 expression within the cancer-associated stroma has not been examined. In the present study, a quantitative RT-PCR-based analysis of laser microdissected tissue confirmed that miR-21 expression is associated with a four-fold mean increase in CRC stroma compared with normal tissue. In situ hybridisation using locked nucleic acid probes localised miR-21 expression predominantly to fibroblasts within tumour-associated stroma. To study the molecular and biological impact of deregulated stromal miR-21 in CRC, stable ectopic expression was induced in immortalised fibroblasts. This resulted in upregulated α-smooth muscle actin expression implying miR-21 overexpression is driving the fibroblast-to-myofibroblast transdifferentiation. Conditioned medium from miR-21-overexpressing fibroblasts protected CRC cells from oxaliplatin-induced apoptosis and increased their proliferative capacity. 3D organotypic co-cultures containing fibroblasts and CRC cells revealed that ectopic stromal miR-21 expression was associated with increased epithelial invasiveness. Reversion-inducing cysteine-rich protein with kazal motifs, an inhibitor of matrix-remodelling enzyme MMP2, was significantly downregulated by ectopic miR-21 in established and primary colorectal fibroblasts with a reciprocal rise in MMP2 activity. Inhibition of MMP2 abrogated the invasion-promoting effects of ectopic miR-21. This data, which characterises a novel pro-metastatic mechanism mediated by miR-21 in the CRC stroma, highlights the importance of miRNA deregulation within the tumour microenvironment and identifies a potential application for stromal miRNAs as biomarkers in cancer.

Molecular characteristics of malignant ovarian germ cell tumors and comparison with testicular counterparts: implications for pathogenesis

This review focuses on the molecular characteristics and development of rare malignant ovarian germ cell tumors (mOGCTs). We provide an overview of the genomic aberrations assessed by ploidy, cytogenetic banding, and comparative genomic hybridization. We summarize and discuss the transcriptome profiles of mRNA and microRNA (miRNA), and biomarkers (DNA methylation, gene mutation, individual protein expression) for each mOGCT histological subtype. Parallels between the origin of mOGCT and their male counterpart testicular GCT (TGCT) are discussed from the perspective of germ cell development, endocrinological influences, and pathogenesis, as is the GCT origin in patients with disorders of sex development. Integrated molecular profiles of the 3 main histological subtypes, dysgerminoma (DG), yolk sac tumor (YST), and immature teratoma (IT), are presented. DGs show genomic aberrations comparable to TGCT. In contrast, the genome profiles of YST and IT are different both from each other and from DG/TGCT. Differences between DG and YST are underlined by their miRNA/mRNA expression patterns, suggesting preferential involvement of the WNT/β-catenin and TGF-β/bone morphogenetic protein signaling pathways among YSTs. Characteristic protein expression patterns are observed in DG, YST and IT. We propose that mOGCT develop through different developmental pathways, including one that is likely shared with TGCT and involves insufficient sexual differentiation of the germ cell niche. The molecular features of the mOGCTs underline their similarity to pluripotent precursor cells (primordial germ cells, PGCs) and other stem cells. This similarity combined with the process of ovary development, explain why mOGCTs present so early in life, and with greater histological complexity, than most somatic solid tumors.

Estradiol regulates miR-135b and mismatch repair gene expressions via estrogen receptor-β in colorectal cells

Estrogen has anti-colorectal cancer effects which are thought to be mediated by mismatch repair gene (MMR) activity. Estrogen receptor (ER) expression is associated with microRNA (miRNA) expression in ER-positive tumors. However, studies of direct link between estrogen (especially estradiol E₂), miRNA expression, and MMR in colorectal cancer (CRC) have not been done. In this study, we first evaluated the effects of estradiol (E₂) and its antagonist ICI182,780 on the expression of miRNAs (miR-31, miR-155 and miR-135b) using COLO205, SW480 and MCF-7 cell lines, followed by examining the association of tissue miRNA expression and serum E₂ levels using samples collected from 18 colorectal cancer patients. E₂ inhibited the expressions of miRNAs in COLO205 cells, which could be reversed by E₂ antagonist ICI 182.780. The expression of miR-135b was inversely correlated with serum E₂ level and ER-β mRNA expression in CRC patients' cancer tissues. There were significant correlations between serum E₂ level and expression of ER-β, miR-135b, and MMR in colon cancer tissue. This study suggests that the effects of estrogen on MMR function may be related to regulating miRNA expression via ER-β, which may be the basis for the anti-cancer effect in colorectal cells.

S100P/RAGE signaling regulates microRNA-155 expression via AP-1 activation in colon cancer

Accumulating evidence indicates that elevated S100P promotes the pathogenesis of cancers, including colon cancer. S100P exerts its effects by binding to and activating the Receptor for Advance Glycation End-products (RAGE). The effects of up-regulated S100P/RAGE signaling on cell functions are well documented. Despite these observations, little is known about the downstream targets of S100P/RAGE signaling. In the present study, we demonstrated for the first time that activation of RAGE by S100P regulates oncogenic microRNA-155 (miR-155) expression through Activator Protein-1 (AP-1) stimulation in colon cancer cells. Ectopic S100P up-regulated miR-155 levels in human colon cancer cells. Conversely, knockdown of S100P resulted in a decrease in miR-155 levels. Exogenous S100P induced miR-155 expression, but blockage of the RAGE with anti-RAGE antibody suppressed the induction of miR-155 by exogenous S100P. Attenuation of AP-1 activation through pharmacological inhibition of MEK activation or genetic inhibition of c-Jun activation using dominant negative c-Jun (TAM67) suppressed miR-155 induction by exogenous S100P. Also, S100P treatment stimulated the enrichment of c-Fos, an AP-1 family member, at the miR-155 host gene promoter site. Finally, a functional study demonstrated that miR-155 knockdown decreases colon cancer cell growth, motility, and invasion. Altogether, these data demonstrate that the expression of miR-155 is regulated by S100P and is dependent on RAGE activation and stimulation of AP-1.

STAT5-mediated expression of oncogenic miR-155 in cutaneous T-cell lymphoma

The pathogenesis of cutaneous T-cell lymphoma (CTCL) remains elusive. Recent discoveries indicate that the oncogenic microRNA miR-155 is overexpressed in affected skin from CTCL patients. Here, we address what drives the expression of miR-155 and investigate its role in the pathogenesis of CTCL. We show that malignant T cells constitutively express high levels of miR-155 and its host gene BIC (B cell integration cluster). Using ChIP-seq, we identify BIC as a target of transcription factor STAT5, which is aberrantly activated in malignant T cells and induced by IL-2/IL-15 in non-malignant T cells. Incubation with JAK inhibitor or siRNA-mediated knockdown of STAT5 decreases BIC/miR-155 expression, whereas IL-2 and IL-15 increase their expression in cell lines and primary cells. In contrast, knockdown of STAT3 has no effect, and BIC is not a transcriptional target of STAT3, indicating that regulation of BIC/miR-155 expression by STAT5 is highly specific. Malignant proliferation is significantly inhibited by an antisense-miR-155 as well as by knockdown of STAT5 and BIC.   In conclusion, we provide the first evidence that STAT5 drives expression of oncogenic BIC/miR-155 in cancer. Moreover, our data indicate that the STAT5/BIC/miR-155 pathway promotes proliferation of malignant T cells, and therefore is a putative target for therapy in CTCL.

Serum microRNAs as promising novel biomarkers for hereditary nonpolyposis colorectal cancer

AIM: To screen and identify serum microRNAs (miRNAs) that might be used as promising biomarkers for hereditary nonpolyposis colorectal cancer using miRNA array and qRT-PCR.

METHODS: Four serum samples from patients with hereditary nonpolyposis colorectal cancer and three serum samples from healthy controls were used to identify potential markers by miRNA array. The results of miRNA array were confirmed by qRT-PCR.

RESULTS: We found 57 up-regulated miRNAs and 30 down-regulated miRNAs by miRNA array, and 8 miRNAs were chosen for further analysis. Three target gene prediction programs were used to predict target genes of these 8 miRNAs, and 294 genes were predicted, all of which were target genes of mir-20a-5p, mir-548b-5p and mir-548as-3p. qPCR analysis confirmed that serum mir-548as-3p was significantly higher in patients with hereditary nonpolyposis colorectal cancer.

CONCLUSION: Our study demonstrates that serum miRNAs are differentially expressed in patients with hereditary nonpolyposis colorectal cancer, and that mir-548as-3p can potentially serve as a noninvasive biomarker for this disease.

Identification of serum microRNA profiles in colon cancer

Background:

microRNAs (miRNAs) exist in blood in an apparently stable form. We have explored whether serum miRNAs can be used as non-invasive early biomarkers of colon cancer.

Methods:

Serum samples from 30 patients with colon cancer stage IV and 10 healthy controls were examined for the expression of 375 cancer-relevant miRNAs. Based on the miRNA profile in this study, 34 selected miRNAs were measured in serum from 40 patients with stage I–II colon cancer and from 10 additional controls.

Results:

Twenty miRNAs were differentially expressed in serum from stage IV patients compared with controls (P<0.01). Unsupervised clustering revealed four subgroups; one corresponding mostly to the control group and the three others to the patient groups. Of the 34 miRNAs measured in the follow-up study of stage I–II patients, 21 showed concordant expression between stage IV and stage I–II patient. Based on the profiles of these 21 miRNAs, a supervised linear regression analysis (Partial Least Squares Regression) was performed. Using this model we correctly assigned stage I–II colon cancer patients based on miRNA profiles of stage IV patients.

Conclusion:

Serum miRNA expression profiling may be utilised in early detection of colon cancer.

Molecular pathological epidemiology of epigenetics: emerging integrative science to analyze environment, host, and disease

Epigenetics acts as an interface between environmental/exogenous factors, cellular responses, and pathological processes. Aberrant epigenetic signatures are a hallmark of complex multifactorial diseases (including neoplasms and malignancies such as leukemias, lymphomas, sarcomas, and breast, lung, prostate, liver, and colorectal cancers). Epigenetic signatures (DNA methylation, mRNA and microRNA expression, etc) may serve as biomarkers for risk stratification, early detection, and disease classification, as well as targets for therapy and chemoprevention. In particular, DNA methylation assays are widely applied to formalin-fixed, paraffin-embedded archival tissue specimens as clinical pathology tests. To better understand the interplay between etiological factors, cellular molecular characteristics, and disease evolution, the field of 'molecular pathological epidemiology (MPE)' has emerged as an interdisciplinary integration of 'molecular pathology' and 'epidemiology'. In contrast to traditional epidemiological research including genome-wide association studies (GWAS), MPE is founded on the unique disease principle, that is, each disease process results from unique profiles of exposomes, epigenomes, transcriptomes, proteomes, metabolomes, microbiomes, and interactomes in relation to the macroenvironment and tissue microenvironment. MPE may represent a logical evolution of GWAS, termed 'GWAS-MPE approach'. Although epigenome-wide association study attracts increasing attention, currently, it has a fundamental problem in that each cell within one individual has a unique, time-varying epigenome. Having a similar conceptual framework to systems biology, the holistic MPE approach enables us to link potential etiological factors to specific molecular pathology, and gain novel pathogenic insights on causality. The widespread application of epigenome (eg, methylome) analyses will enhance our understanding of disease heterogeneity, epigenotypes (CpG island methylator phenotype, LINE-1 (long interspersed nucleotide element-1; also called long interspersed nuclear element-1; long interspersed element-1; L1) hypomethylation, etc), and host-disease interactions. In this article, we illustrate increasing contribution of modern pathology to broader public health sciences, which attests pivotal roles of pathologists in the new integrated MPE science towards our ultimate goal of personalized medicine and prevention.

Epigenetic field defects in progression to cancer

A field defect is a field of pre-malignant tissue in which a new cancer is likely to arise. Field defects often appear to be histologically normal under the microscope. Recent research indicates that cells within a field defect characteristically have an increased frequency of epigenetic alterations and these may be fundamentally important as underlying factors in progression to cancer. However, understanding of epigenetic field defects is at an early stage, and the work of Katsurano et al published this year, is a key contribution to this field. One question examined by Katsurano et al was how early could the formation of an epigenetic field defect be detected in a mouse colitis model of tumorigenesis. They highlighted a number of measurable epigenetic alterations, detected very early in normal appearing tissue undergoing histologically invisible tumorigenesis. They also documented the increasing presence of the epigenetic alterations at successive times during progression to cancer. In this commentary, we offer a perspective on the changes they observed within a broader sequence of epigenetic events that occur in progression to cancer. In particular, we highlight the likely central role of epigenetic deficiencies in DNA repair gene expression that arise during progression to cancer.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

Molecular aspects of upper tract urothelial carcinoma

OBJECTIVES

Primary upper tract urothelial carcinoma (UTUC) is a relatively rare tumor with up to 60% of cases being muscle invasive at presentation. In this article we review the molecular biology of UTUC, an understanding of which may help to address some of the dilemmas surrounding the diagnosis and treatment of this disease and ultimately lead to the introduction of personalized treatment plans.

METHODS

The literature search on the molecular aspects of UTUC was performed using the National Library of Medicine database.

RESULTS

UTUC and urothelial carcinomas of the bladder share many common biological pathways. UTUC are more commonly associated with conditions such as Balkan Endemic Nephropathy and Hereditary Non Polyposis Colon Cancer (HNPCC), the molecular basis of which is now being understood. A large number of potential biomarkers have been studied to help identify robust prognostic markers in UTUC.

CONCLUSION

Advances in our understanding of the biology of UTUC is may in the future help to identify novel druggable targets, clinically applicable biomarkers and guide treatment of the rare but lethal condition.

Micro-RNAs in inflammatory diseases and as a link between inflammation and cancer

OBJECTIVE

The objective of this review is to examine the role of miRNA in various inflammatory diseases and in inflammatory diseases progressing to cancer.

INTRODUCTION

MicroRNAs are small, conserved, non-coding RNA molecules which are present in most of the eukaryotes. miRNA have been reported to play a major role in the physiological control of gene expression and in the pathogenesis of various diseases. They regulate the gene expression mainly at the post-transcriptional level. miRNA expression profile is reported to be altered in various inflammatory diseases and subsequently affects the expression of genes, which is important in disease pathogenesis.

METHODS

A Pubmed database search was performed for studies related to miRNA studies in inflammatory disease, cancer and in inflammatory diseases progressing to cancer.

CONCLUSION

The evidence shows very important role of miRNA in inflammatory diseases. Few miRNAs involved in common inflammatory process and suggest miRNA as a link between inflammation and cancer. Future research should be directed to use miRNA therapeutically to target common inflammatory pathway and to develop miRNA as biomarker to detect development of cancer at early stages.

Overexpression of microRNAs-155 and 21 targeting mismatch repair proteins in inflammatory bowel diseases

Microsatellite instability (MSI) due to mismatch repair (MMR) deficiency is reported in 5-10% of colorectal cancers (CRCs) complicating inflammatory bowel diseases (IBD). The molecular mechanisms underlying MMR deficiency may be different in IBD CRCs, and in sporadic and hereditary MSI tumors. Here, we hypothesize that overexpression of miR-155 and miR-21, two inflammation-related microRNAs that target core MMR proteins, may constitute a pre-neoplastic event for the development of MSI IBD CRCs. We studied miR-155 and miR-21 expression using real-time quantitative PCR in MSI (n = 10) and microsatellite stable (n = 10) IBD CRCs, and in MSI (n = 32) and microsatellite stable (n = 30) non-IBD CRCs. We also screened colonic samples from IBD patients without cancer (n = 18) and used healthy colonic mucosa as controls (n = 20). MiR-155 and miR-21 appeared significantly overexpressed not only in the colonic mucosa of IBD subjects without CRC but also in neoplastic tissues of IBD patients compared with non-IBD controls (P < 0.001). Importantly, in patients with IBD CRCs, miR-155 and miR-21 overexpression extended to the distant non-neoplastic mucosa (P < 0.001). Ratios of expressions in tumors versus matched distant mucosa revealed a nearly significant association between miR-155 overexpression and MSI in IBDs (P = 0.057). These results show a strong deregulation of both MMR-targeting microRNAs in IBD subjects with or without cancer. MiR-155 overexpression being particularly associated to MSI IBD CRCs and extending to distant non-neoplastic mucosa, strongly suggests that a pre-neoplastic miR-155 field defect may promote MSI-driven transformation of the colonic mucosa. The detection and monitoring of miR-155 field defect may, therefore, have implications for the prevention and treatment of MSI IBD CRCs.