Functional evidence that Drosha overexpression in cervical squamous cell carcinoma affects cell phenotype and microRNA profiles

Regulation of KLRC and Ceacam gene expression by miR-141 supports cell proliferation and metastasis in cervical cancer cells

INTRODUCTION

MicroRNAs (miRNAs) are single RNA molecules that act as global regulators of gene expression in mammalian cells and thus constitute attractive targets in treating cancer. Here we aimed to investigate the possible involvement of miRNA-141 (miR-141) in cervical cancer and to identify its potential targets in cervical cancer cell lines.

METHODS

The level of miR-141 in HeLa and C-33A cells has been assessed using the quantitative real-time PCR (qRT-PCR). A new miR-141 construct has been performed in a CMV promoter vector tagged with GFP. Using microarray analysis, we identified the potentially regulated genes by miR-141 in transfected HeLa cells. The protein profile of killer-like receptor C1 (KLRC1), KLRC3, carcinoembryonic antigen-related cell adhesion molecule 3 (CAM3), and CAM6 was investigated in HeLa cells transfected with either an inhibitor, antagonist miR-141, or miR-141 overexpression vector using immunoblotting and flow cytometry assay. Finally, ELISA assay has been used to monitor the produced cytokines from transfected HeLa cells.

RESULTS

The expression of miR-141 significantly increased in HeLa and C-33A cells compared to the normal cervical HCK1T cell line. Transfection of HeLa cells with an inhibitor, antagonist miR-141, showed a potent effect on cancer cell viability, unlike the transfection of miR-141 overexpression vector. The microarray data of HeLa cells overexpressed miR-141 provided a hundred of downregulated genes, including KLRC1, KLRC3, CAM3, and CAM6. KLRC1 and KLRC3 expression profiles markedly depleted in HeLa cells transfected with miR-141 overexpression accompanied by decreasing interleukin 8 (IL-8), indicating the role of miR-141 in avoiding programmed cells death in HeLa cells. Likewise, CAM3 and CAM6 expression reduced markedly in miR-141 transduced cells accompanied by an increasing level of transforming growth factor beta (TGF-β), indicating the impact of miR-141 in cancer cell migration. The IntaRNA program and miRWalk were used to check the direct interaction and potential binding sites between miR-141 and identified genes. Based on this, the seeding regions of each potential target was cloned upstream of the luciferase reporter gene in the pGL3 control vector. Interestingly, the luciferase activities of constructed vectors were significantly decreased in HeLa cells pre-transfected with miR-141 overexpression vector, while increasing enormously in cells pre-transfected with miR-141 specific inhibitor.

CONCLUSION

Together, these data uncover an efficient miR-141-based mechanism that supports cervical cancer progression and identifies miR-141 as a credible therapeutic target.

MiRNA in cervical cancer: Diagnosis to therapy: Systematic review

Cancers are one of the most public health problems worldwide. Among them, cervical cancer (CC) is the fourth most prevalent cancer with 604 000 new cases and 342 000 deaths. Mostly, it is associated with Human papillomavirus (HPV). It has been caused by the aggregation of genetic and epigenetic modifications in cervical epithelial cells. Although genetic mutations are given great attention for the carcinogenesis of CC, epigenetic changes have emerged as a hotspot area for CC biomarkers research with great implications for early diagnosis, prognosis, and treatment response prediction of the disease. Recently, there are several studies focused on miRNAs as biomarkers of cervical cancer. However, the precise function of miRNAs in the development of cervical cancer is not still completely understood, particularly when it comes to unconventional sampling materials like cervical mucus and plasma serum. Hence, this review article will give a summary of the miRNAs profiles that emerge at different stages of cervical cancer progression and their downstream effects on target genes and associated signaling pathways. Finally, these results may provide insight into the use of miRNAs as biomarkers for the prediction or diagnosis of cervical cancer or the development of miRNA-based therapeutics against cervical cancer.

Emerging role of miRNA in prostate cancer: A future era of diagnostic and therapeutics

Prostate cancer (PCa) is the most common cancer in men (20%) and is responsible for 6.8% (1/5) of all cancer-related deaths in men around the world. The development and spread of prostate cancer are driven by a wide variety of genomic changes and extensive epigenetic events. Because of this, the MicroRNA (miRNA) and associated molecular mechanisms involved in PCa genesis and aggressive were only partially identified until today. The miRNAs are a newly discovered category of regulatorsthat have recently been recognized to have a significant role in regulating numerous elements of cancer mechanisms, such as proliferation, differentiation, metabolism, and apoptosis. The miRNAs are a type of small (22-24 nucleotides), non-coding, endogenous, single-stranded RNA and work as potent gene regulators. Various types of cancer, including PCa, have found evidence that miRNA genes, which are often located in cancer-related genetic regions or fragile locations, have a role in the primary steps of tumorigenesis, either as oncogenes or tumorsuppressors. To explain the link between miRNAs and their function in the initiation and advancement of PCa, we conducted a preliminary assessment. The purpose of this research was to enhance our understanding of the connection between miRNA expression profiles and PCa by elucidating the fundamental processes of miRNA expression and the target genes.

Non-coding RNAs in gynecologic cancer

The term "gynecologic cancer" pertains to neoplasms impacting the reproductive tissues and organs of women encompassing the endometrium, vagina, cervix, uterus, vulva, and ovaries. The progression of gynecologic cancer is linked to various molecular mechanisms. Historically, cancer research primarily focused on protein-coding genes. However, recent years have unveiled the involvement of non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs (LncRNAs), and circular RNAs, in modulating cellular functions within gynecological cancer. Substantial evidence suggests that ncRNAs may wield a dual role in gynecological cancer, acting as either oncogenic or tumor-suppressive agents. Numerous clinical trials are presently investigating the roles of ncRNAs as biomarkers and therapeutic agents. These endeavors may introduce a fresh perspective on the diagnosis and treatment of gynecological cancer. In this overview, we highlight some of the ncRNAs associated with gynecological cancers.

Head and neck cancer treatment in the era of molecular medicine

Head and neck cancers are a heterogeneous group of highly aggressive tumors and collectively represent the sixth most common cancer worldwide. Most head and neck cancers are squamous cell carcinomas (HNSCCs). Current multimodal treatment concepts combine surgery, chemotherapy, irradiation, immunotherapy, and targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of HNSCC and revealed novel therapeutic targets and prognostic/predictive biomarkers. Notably, HNSCC is characterized by complex relations between stromal, epithelial, and immune cells within the tumor microenvironment (TME). The TME consists of different subsets of immune cells that infiltrate the tumors and interact with the tumor cells or with each other. Understanding multiple pivotal factors in HNSCC tumorigenesis and tumor progression may help define novel targets and develop more effective therapies for patients. This review provides a comprehensive overview of the latest advances in the molecular biology of HNSCC and their effects on clinical oncology; it is meant for a broad readership in the head and neck cancers field.

miRNAs and arsenic-induced carcinogenesis

Arsenic-induced carcinogenesis is a worldwide health problem. Identifying the molecular mechanisms responsible for the induction of arsenic-induced cancers is important for developing treatment strategies. MicroRNA (miRNA) dysregulation is known to affect development and progression of human cancer. Several studies have identified an association between altered miRNA expression in cancers from individuals chronically exposed to arsenic and in cell models for arsenic-induced carcinogenesis. This chapter provides a comprehensive review for miRNA dysregulation in arsenic-induced cancer.

The clinical utility of dysregulated microRNA expression in paediatric solid tumours

MicroRNAs (miRNAs) are short, non-protein-coding genes that regulate the expression of numerous protein-coding genes. Their expression is dysregulated in cancer, where they may function as oncogenes or tumour suppressor genes. As miRNAs are highly resistant to degradation, they are ideal biomarker candidates to improve the diagnosis and clinical management of cancer, including prognostication. Furthermore, miRNAs dysregulated in malignancy represent potential therapeutic targets. The use of miRNAs for these purposes is a particularly attractive option to explore for paediatric malignancies, where the mutational burden is typically low, in contrast to cancers affecting adult patients. As childhood cancers are rare, it has taken time to accumulate the necessary body of evidence showing the potential for miRNAs to improve clinical management across this group of tumours. Here, we review the current literature regarding the potential clinical utility of miRNAs in paediatric solid tumours, which is now both timely and justified. Exploring such avenues is warranted to improve the management and outcomes of children affected by cancer.

Mechanisms Controlling MicroRNA Expression in Tumor

MicroRNAs (miRNAs) are widely present in many organisms and regulate the expression of genes in various biological processes such as cell differentiation, metabolism, and development. Numerous studies have shown that miRNAs are abnormally expressed in tumor tissues and are closely associated with tumorigenesis. MiRNA-based cancer gene therapy has consistently shown promising anti-tumor effects and is recognized as a new field in cancer treatment. So far, some clinical trials involving the treatment of malignancies have been carried out; however, studies of miRNA-based cancer gene therapy are still proceeding slowly. Therefore, furthering our understanding of the regulatory mechanisms of miRNA can bring substantial benefits to the development of miRNA-based gene therapy or other combination therapies and the clinical outcome of patients with cancer. Recent studies have revealed that the aberrant expression of miRNA in tumors is associated with promoter sequence mutation, epigenetic alteration, aberrant RNA modification, etc., showing the complexity of aberrant expression mechanisms of miRNA in tumors. In this paper, we systematically summarized the regulation mechanisms of miRNA expression in tumors, with the aim of providing assistance in the subsequent elucidation of the role of miRNA in tumorigenesis and the development of new strategies for tumor prevention and treatment.

The Dysregulation of MicroRNAs in the Development of Cervical Pre-Cancer—An Update

Globally in 2020, an estimated ~600,000 women were diagnosed with and 340,000 women died from cervical cancer. Compared to 2012, the number of cases increased by 7.5% and the number of deaths increased by 17%. MiRNAs are involved in multiple processes in the pathogenesis of cervical cancer. Dysregulation of miRNAs in the pre-stage of cervical cancer is the focus of this review. Here we summarize the dysregulated miRNAs in clinical samples from cervical pre-cancer patients and relate them to the early transformation process owing to human papillomavirus (HPV) infection in the cervical cells. When HPV infects the normal cervical cells, the DNA damage response is initiated with the involvement of HPV’s E1 and E2 proteins. Later, cell proliferation and cell death are affected by the E6 and E7 proteins. We find that the expressions of miRNAs in cervical pre-cancerous tissue revealed by different studies seldom agreed with each other. The discrepancy in sample types, samples’ HPV status, expression measurement, and methods for analysis contributed to the non-aligned results across studies. However, several miRNAs (miR-34a, miR-9, miR-21, miR-145, and miR-375) were found to be dysregulated across multiple studies. In addition, there are hints that the DNA damage response and cell growth response induced by HPV during the early transformation of the cervical cells are related to these miRNAs. Currently, no review articles analyse the relationship between the dysregulated miRNAs in cervical pre-cancerous tissue and their possible roles in the early processes involving HPV’s protein encoded by the early genes and DNA damage response during normal cell transformation. Our review provides insight on spotting miRNAs involved in the early pathogenic processes and pointing out their potential as biomarker targets of cervical pre-cancer.

RANBP1 promotes colorectal cancer progression by regulating pre-miRNA nuclear export via a positive feedback loop with YAP

Colorectal cancer (CRC) is among the top five most common malignant tumors worldwide and has a high mortality rate. Identification of the mechanism of CRC and potential therapeutic targets is critical for improving survival. In the present study, we observed high expression of RAN binding protein 1 (RANBP1) in CRC tissues. Upregulated RANBP1 expression was strongly associated with TNM stages and was an independent risk factor for poor prognosis. In vitro and in vivo functional experiments demonstrated that RANBP1 promoted the proliferation and invasion of CRC cells and inhibited the apoptosis of CRC cells. Low RANBP1 expression reduced the expression levels of hsa-miR-18a, hsa-miR-183, and hsa-miR-106 microRNAs (miRNAs) by inhibiting the nucleoplasmic transport of precursor miRNAs (pre-miRNAs), thereby promoting the accumulation of the latter in the nucleus and reducing the expression of mature miRNAs. Further experiments and bioinformatic analyses demonstrated that RANBP1 promoted the expression of YAP by regulating miRNAs and the Hippo pathway. We also found that YAP acted as a transcriptional cofactor to activate RANBP1 transcription in combination with TEAD4 transcription factor. Thus, RANBP1 further promoted the progression of CRC by forming a positive feedback loop with YAP. Our results revealed the biological role and mechanism of RANBP1 in CRC for the first time, suggesting that RANBP1 can be used as a diagnostic molecule and a potential therapeutic target in CRC.

MicroRNAs in Genetic Etiology of Human Diseases

Since their first discovery more than 20 years ago, miRNAs have been subject to deliberate research and analysis for revealing their physiological or pathological involvement. Regulatory roles of miRNAs in signal transduction, gene expression, and cellular processes in development, differentiation, proliferation, apoptosis, and homeostasis also imply their critical role in disease pathogenesis. Their roles in cancer, neurodegenerative diseases, and other systemic diseases have been studied broadly. In these regulatory pathways, their mutations and target sequence variations play critical roles to determine their functional repertoire. In this chapter, we summarize studies that investigated the role of mutations, polymorphisms, and other variations of miRNAs in respect to pathological processes.

Cervical Cancer, Papillomavirus, and miRNA Dysfunction

Cervical cancer is the leading cause of death by cancer in women from developing countries. Persistent infection with high-risk human papillomavirus (HPV) types 16 and 18 is a major risk factor for cervical carcinogenesis. Nevertheless, only a few women with morphologic expression of HPV infection progress into invasive disease suggesting the involvement of other factors in cervical carcinogenesis. MicroRNAs (miRNAs) are conserved small non-coding RNAs that negatively regulate gene expression including genes involved in fundamental biological processes and human cancer. Dysregulation of miRNAs has been widely reported in cervical cancer. This work focuses on reviewing the miRNAs affected during the HPV infection process, as well relevant miRNAs that contribute to the development and maintenance of malignant cervical tumor cells. Finally, we recapitulate on miRNAs that may be used to distinguish between healthy individuals from patients with precancerous lesions or cervical tumors.

Classical and noncanonical functions of miRNAs in cancers

Alterations in microRNAs (miRNAs) expression are causative in the initiation and progression of human cancers. The molecular events responsible for the widespread differential expression of miRNAs in malignancy are exemplified by their location in cancer-associated genomic regions, epigenetic mechanisms, transcriptional dysregulation, chemical modifications and editing, and alterations in miRNA biogenesis proteins. The classical miRNA function is synonymous with post-transcriptional repression of target protein genes. However, several studies have reported miRNAs functioning outside this paradigm and some of these novel modes of regulation of gene expression have been implicated in cancers. Here, we summarize key aspects of miRNA involvement in cancer, with a special focus on these lesser-studied mechanisms of action.

MicroRNAs as Biomarkers for Early Diagnosis, Prognosis, and Therapeutic Targeting of Ovarian Cancer

Ovarian cancer is the major cause of gynecologic cancer-related mortality. Regardless of outstanding advances, which have been made for improving the prognosis, diagnosis, and treatment of ovarian cancer, the majority of the patients will die of the disease. Late-stage diagnosis and the occurrence of recurrent cancer after treatment are the most important causes of the high mortality rate observed in ovarian cancer patients. Unraveling the molecular mechanisms involved in the pathogenesis of ovarian cancer may help find new biomarkers and therapeutic targets for ovarian cancer. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression, mostly at the posttranscriptional stage, through binding to mRNA targets and inducing translational repression or degradation of target via the RNA-induced silencing complex. Over the last two decades, the role of miRNAs in the pathogenesis of various human cancers, including ovarian cancer, has been documented in multiple studies. Consequently, these small RNAs could be considered as reliable markers for prognosis and early diagnosis. Furthermore, given the function of miRNAs in various cellular pathways, including cell survival and differentiation, targeting miRNAs could be an interesting approach for the treatment of human cancers. Here, we review our current understanding of the most updated role of the important dysregulation of miRNAs and their roles in the progression and metastasis of ovarian cancer. Furthermore, we meticulously discuss the significance of miRNAs as prognostic and diagnostic markers. Lastly, we mention the opportunities and the efforts made for targeting ovarian cancer through inhibition and/or stimulation of the miRNAs.

Micro-RNA: The darkhorse of cancer

The discovery of micro RNAs (miRNA) in cancer has opened up new vistas for researchers in recent years. Micro RNAs area set of small, endogenous, highly conserved, non-coding RNAs that control the expression of about 30% genes at post-transcriptional levels. Typically, microRNAs impede the translation and stability of messenger RNAs (mRNA), control genes associated with cellular processes namely inflammation, cell cycle regulation, stress response, differentiation, apoptosis, and migration. Compelling findings revealed that miRNA mutations or disruption correspond to diverse human cancers and suggest that miRNAs can function as tumor suppressors or oncogenes. Here we summarize the literature on these master regulators in clinical settings from last three decades as both abrupt cancer therapeutics and as an approach to sensitize tumors to chemotherapy. This review highlights (I) the prevailing perception of miRNA genomics, biogenesis, as well as function; (II) the significant advancements in regulatory mechanisms in the expression of carcinogenic genes; and (III) explains, how miRNA is utilized as a diagnostic and prognostic biomarker for the disease stage indicating survival as well as therapeutic targets in cancer.

microRNAs Biogenesis, Functions and Role in Tumor Angiogenesis

microRNAs (miRNAs) are small non-coding RNA molecules, evolutionary conserved. They target more than one mRNAs, thus influencing multiple molecular pathways, but also mRNAs may bind to a variety of miRNAs, either simultaneously or in a context-dependent manner. miRNAs biogenesis, including miRNA transcription, processing by Drosha and Dicer, transportation, RISC biding, and miRNA decay, are finely controlled in space and time. miRNAs are critical regulators in various biological processes, such as differentiation, proliferation, apoptosis, and development in both health and disease. Their dysregulation is involved in tumor initiation and progression. In tumors, they can act as onco-miRNAs or oncosuppressor-miRNA participating in distinct cellular pathways, and the same miRNA can perform both activities depending on the context. In tumor progression, the angiogenic switch is fundamental. miRNAs derived from tumor cells, endothelial cells, and cells of the surrounding microenvironment regulate tumor angiogenesis, acting as pro-angiomiR or anti-angiomiR. In this review, we described miRNA biogenesis and function, and we update the non-classical aspects of them. The most recent role in the nucleus, as transcriptional gene regulators and the different mechanisms by which they could be dysregulated, in tumor initiation and progression, are treated. In particular, we describe the role of miRNAs in sprouting angiogenesis, vessel co-option, and vasculogenic mimicry. The role of miRNAs in lymphoma angiogenesis is also discussed despite the scarcity of data. The information presented in this review reveals the need to do much more to discover the complete miRNA network regulating angiogenesis, not only using high-throughput computational analysis approaches but also morphological ones.

Role of cellular, molecular and tumor microenvironment in hepatocellular carcinoma: Possible targets and future directions in the regorafenib era

Hepatocellular carcinoma (HCC) remains as one of the major causes of cancer-related mortality, despite the recent development of new therapeutic options. Regorafenib, an oral multikinase inhibitor, is the first systemic therapy that has a survival benefit for patients with advanced HCC that have a poor response to sorafenib. Even though regorafenib has been approved by the FDA, the clinical trial for regorafenib treatment does not show significant improvement in overall survival. The impaired efficacy of regorafenib caused by various resistance mechanisms, including epithelial-mesenchymal transitions, inflammation, angiogenesis, hypoxia, oxidative stress, fibrosis and autophagy, still needs to be resolved. In this review, we provide insight on regorafenib microenvironmental, molecular and cellular mechanisms and interactions in HCC treatment. The aim of this review is to help physicians select patients that would obtain the maximal benefits from regorafenib in HCC therapy.

Regulatory Mechanism of MicroRNA Expression in Cancer

Altered gene expression is the primary molecular mechanism responsible for the pathological processes of human diseases, including cancer. MicroRNAs (miRNAs) are virtually involved at the post-transcriptional level and bind to 3' UTR of their target messenger RNA (mRNA) to suppress expression. Dysfunction of miRNAs disturbs expression of oncogenic or tumor-suppressive target genes, which is implicated in cancer pathogenesis. As such, a large number of miRNAs have been found to be downregulated or upregulated in human cancers and to function as oncomiRs or oncosuppressor miRs. Notably, the molecular mechanism underlying the dysregulation of miRNA expression in cancer has been recently uncovered. The genetic deletion or amplification and epigenetic methylation of miRNA genomic loci and the transcription factor-mediated regulation of primary miRNA often alter the landscape of miRNA expression in cancer. Dysregulation of the multiple processing steps in mature miRNA biogenesis can also cause alterations in miRNA expression in cancer. Detailed knowledge of the regulatory mechanism of miRNAs in cancer is essential for understanding its physiological role and the implications of cancer-associated dysfunction and dysregulation. In this review, we elucidate how miRNA expression is deregulated in cancer, paying particular attention to the cancer-associated transcriptional and post-transcriptional factors that execute miRNA programs.

miRNAs as Biomarkers in Disease: Latest Findings Regarding Their Role in Diagnosis and Prognosis

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs with the main roles of regulating mRNA through its degradation and adjusting protein levels. In recent years, extraordinary progress has been made in terms of identifying the origin and exact functions of miRNA, focusing on their potential use in both the research and the clinical field. This review aims at improving the current understanding of these molecules and their applicability in the medical field. A thorough analysis of the literature consulting resources available in online databases such as NCBI, PubMed, Medline, ScienceDirect, and UpToDate was performed. There is promising evidence that in spite of the lack of standardized protocols regarding the use of miRNAs in current clinical practice, they constitute a reliable tool for future use. These molecules meet most of the required criteria for being an ideal biomarker, such as accessibility, high specificity, and sensitivity. Despite present limitations, miRNAs as biomarkers for various conditions remain an impressive research field. As current techniques evolve, we anticipate that miRNAs will become a routine approach in the development of personalized patient profiles, thus permitting more specific therapeutic interventions.

MicroRNAs Contribute to Breast Cancer Invasiveness

Cancer statistics in 2018 highlight an 8.6 million incidence in female cancers, and 4.2 million cancer deaths globally. Moreover, breast cancer is the most frequent malignancy in females and twenty percent of these develop metastasis. This provides only a small chance for successful therapy, and identification of new molecular markers for the diagnosis and prognostic prediction of metastatic disease and development of innovative therapeutic molecules are therefore urgently required. Differentially expressed microRNAs (miRNAs) in cancers cause multiple changes in the expression of the tumorigenesis-promoting genes which have mostly been investigated in breast cancers. Herein, we summarize recent data on breast cancer-specific miRNA expression profiles and their participation in regulating invasive processes, in association with changes in cytoskeletal structure, cell-cell adhesion junctions, cancer cell-extracellular matrix interactions, tumor microenvironments, epithelial-to-mesenchymal transitions and cancer cell stem abilities. We then focused on the epigenetic regulation of individual miRNAs and their modified interactions with other regulatory genes, and reviewed the function of miRNA isoforms and exosome-mediated miRNA transfer in cancer invasiveness. Although research into miRNA’s function in cancer is still ongoing, results herein contribute to improved metastatic cancer management.

Altered microRNA processing proteins in HPV-induced cancers

High-risk human papilloma virus (hrHPV) infections are associated with the development of anogenital cancers, in particular cervical cancer, and a subset of head and neck cancers. Previous studies have shown that microRNAs (miRNAs) contribute to the development and progression of HPV-induced malignancies. miRNAs are small non-coding RNAs that exist as multiple length and sequence variants, termed isomiRs. Efficient processing of miRNAs and generation of isomiRs is accomplished by several processing proteins. Deregulation of Drosha, AGO2, and TENT2, among others, has been observed in HPV-induced cancers and was even found at the precancerous stage. This suggests that miRNA processing proteins may be involved during early cancer development and that the generated isomiRs could provide promising biomarkers for early cancer diagnosis.

The Epigenetic Regulation of HCC Metastasis

Epigenetic alterations, such as histone modification, DNA methylation, and miRNA-mediated processes, are critically associated with various mechanisms of proliferation and metastasis in several types of cancer. To overcome the side effects and limited effectiveness of drugs for cancer treatment, there is a continuous need for the identification of more effective drug targets and the execution of mechanism of action (MOA) studies. Recently, epigenetic modifiers have been recognized as important therapeutic targets for hepatocellular carcinoma (HCC) based on their reported abilities to suppress HCC metastasis and proliferation in both in vivo and in vitro studies. Therefore, here, we introduce epigenetic modifiers and alterations related to HCC metastasis and proliferation, and their molecular mechanisms in HCC metastasis. The existing data suggest that the study of epigenetic modifiers is important for the development of specific inhibitors and diagnostic targets for HCC treatment.

Oncogenic microRNA signature for early diagnosis of cervical intraepithelial neoplasia and cancer

Cervical cancer is one of the leading causes of cancer death in women globally, despite the widespread use of cytology/human papillomavirus (HPV) screening. In the present study, we aimed to identify the potential role of microRNA (miRNA) as a diagnostic biomarker in the detection of cervical pre‐malignant lesions and cancer. In total, we recruited 582 patients with cervical diseases and 145 control individuals. The expression levels of six miRNAs (miR‐20a, miR‐92a, miR‐141, miR‐183*, miR‐210 and miR‐944) were found to be significantly up‐regulated in cervical cancer and pre‐malignant lesions compared to normal cervical samples, indicating that they are oncogenic miRNAs. Receiver operating characteristic curve analysis showed that these six miRNAs can be used to distinguish patients with cervical pre‐malignant lesions or cancer from normal individuals and they also had a good predictive performance, particularly in cervical lesions. Combined use of these six miRNAs further enhanced the diagnostic accuracy over any single miRNA marker, with an area under the curve of 0.998, 0.996 and 0.959, a diagnostic sensitivity of 97.9%, 97.2% and 91.4%, and a specificity of 98.6%, 96.6% and 87.6% for low‐grade lesions, high‐grade lesions and cancer, respectively. This six oncogenic miRNA signature may be suitable for use as diagnostic marker for cervical pre‐malignant lesions and cancer in the near future.

The Nefarious Nexus of Noncoding RNAs in Cancer

The past decade has witnessed enormous progress, and has seen the noncoding RNAs (ncRNAs) turn from the so-called dark matter RNA to critical functional molecules, influencing most physiological processes in development and disease contexts. Many ncRNAs interact with each other and are part of networks that influence the cell transcriptome and proteome and consequently the outcome of biological processes. The regulatory circuits controlled by ncRNAs have become increasingly more relevant in cancer. Further understanding of these complex network interactions and how ncRNAs are regulated, is paving the way for the identification of better therapeutic strategies in cancer.

Dysregulation of miRNAs in bladder cancer: altered expression with aberrant biogenesis procedure

Aberrant expression profiles of miRNAs are widely observed in the clinical tissue specimens and urine samples as well as the blood samples of bladder cancer patients. These profiles are closely related to the pathological features of bladder cancer, such as the tumour stage/grade, metastasis, recurrence and chemo-sensitivity. MiRNA biogenesis forms the basis of miRNA expression and function, and its dysregulation has been shown to be essential for variations in miRNA expression profiles as well as tumourigenesis and cancer progression. In this review, we summarize the up-to-date and widely reported miRNAs in bladder cancer that display significantly altered expression. We then compare the miRNA expression profiles among three different sample types (tissue, urine and blood) from patients with bladder cancer. Moreover, for the first time, we outline the dysregulated miRNA biogenesis network in bladder cancer from different levels and analyse its possible relationship with aberrant miRNA expression and the pathological characteristics of the disease.

Immortalization capacity of HPV types is inversely related to chromosomal instability

High-risk human papillomavirus (hrHPV) types induce immortalization of primary human epithelial cells. Previously we demonstrated that immortalization of human foreskin keratinocytes (HFKs) is HPV type dependent, as reflected by the presence or absence of a crisis period before reaching immortality. This study determined how the immortalization capacity of ten hrHPV types relates to DNA damage induction and overall genomic instability in HFKs.

Twenty five cell cultures obtained by transduction of ten hrHPV types (i.e. HPV16/18/31/33/35/45/51/59/66/70 E6E7) in two or three HFK donors each were studied.

All hrHPV-transduced HFKs showed an increased number of double strand DNA breaks compared to controls, without exhibiting significant differences between types. However, immortal descendants of HPV-transduced HFKs that underwent a prior crisis period (HPV45/51/59/66/70-transduced HFKs) showed significantly more chromosomal aberrations compared to those without crisis (HPV16/18/31/33/35-transduced HFKs). Notably, the hTERT locus at 5p was exclusively gained in cells with a history of crisis and coincided with increased expression. Chromothripsis was detected in one cell line in which multiple rearrangements within chromosome 8 resulted in a gain of MYC.

Together we demonstrated that upon HPV-induced immortalization, the number of chromosomal aberrations is inversely related to the viral immortalization capacity. We propose that hrHPV types with reduced immortalization capacity in vitro, reflected by a crisis period, require more genetic host cell aberrations to facilitate immortalization than types that can immortalize without crisis. This may in part explain the observed differences in HPV-type prevalence in cervical cancers and emphasizes that changes in the host cell genome contribute to HPV-induced carcinogenesis.

Circulating cell-free microRNAs as clinical cancer biomarkers

MicroRNAs (miRNAs) are non-coding small RNAs that are master regulators of genic expression and consequently of many cellular processes. But their expression is often deregulated in human tumors leading to cancer development. Recently miRNAs were discovered in body fluids (serum, plasma and others) and their levels have often been reported to be altered in patients. Circulating miRNAs became one of the most promising biomarkers in oncology for early diagnosis, prognosis and therapeutic response prediction. Here we describe the origins and roles of miRNAs, and summarize the most recent studies focusing on their usefulness as cancer biomarkers in lung, breast, colon, prostate, ovary cancers and melanoma. Lastly, we describe the main methodologies related to miRNA detection, which should be standardized for their use in clinical practice.

Perturbation of DROSHA and DICER expression by human papillomavirus 16 oncoproteins

Many tumors, including cervical carcinoma, show dysregulated expression of the microRNA processing machinery, specifically DROSHA and DICER. Some cervical cancers exhibit chromosome 5p amplifications and DROSHA is the most significantly upregulated transcript and is observed in all tumors with 5p gain. DROSHA and DICER mRNA levels, however, are higher in HPV positive cancer lines than in an HPV negative cervical carcinoma line. We show that high-risk HPV E6/E7 expression in HPV negative C33A cervical carcinoma cells and primary human epithelial cell causes increased expression of DROSHA and DICER mRNA and protein. Most importantly, many DROSHA regulated microRNAs are dysregulated in HPV16 E6/E7 expressing cells. These results suggest that increased DROSHA levels contribute to HPV16 E6/E7 dysregulation of cellular microRNA expression.

Nuclear Drosha enhances cell invasion via an EGFR-ERK1/2-MMP7 signaling pathway induced by dysregulated miRNA-622/197 and their targets LAMC2 and CD82 in gastric cancer

Drosha is an RNA III-like enzyme that has an aberrant expression in some tumors. Our previous studies showed the aberrant Drosha in gastric tumors. However, the roles of nuclear Drosha, the main regulator of microRNA (miRNA) biogenesis, in gastric cancer (GC) progression remain poorly understood. In this study, we demonstrated that nuclear Drosha is significantly associated with cell invasion of GC and that Drosha silence impedes the tumor invasion. Knockdown of Drosha led to a set of dysregulated miRNAs in GC cells. Multiple targets of these miRNAs were the members in cell migration, invasion and metastasis-associated signaling (e.g. ECM-receptor interaction, focal adhesion, p53 signaling and MAPK signaling pathway) revealed by bioinformatics analysis. LAMC2 (a key element of ECM-receptor signaling) and CD82 (a suppressor of p53 signaling) are the targets of miR-622 and miR-197, respectively. High levels of LAMC2 and low levels of CD82 were significantly related to the worse outcome for GC patients. Furthermore, overexpression of LAMC2 and knockdown of CD82 markedly promoted GC cell invasion and activated EGFR/ERK1/2-MMP7 signaling via upregulation of the expression of phosphorylated (p)-EGFR, p-ERK1/2 and MMP7. Our findings suggest that nuclear Drosha potentially has a role in the development of GC.

High copy number variation of cancer-related microRNA genes and frequent amplification of DICER1 and DROSHA in lung cancer

A growing body of evidence indicates that miRNAs may be a class of genetic elements that can either drive or suppress oncogenesis. In this study we analyzed the somatic copy number variation of 14 miRNA genes frequently found to be either over- or underexpressed in lung cancer, as well as two miRNA biogenesis genes, DICER1 and DROSHA, in non-small-cell lung cancer (NSCLC). Our analysis showed that most analyzed miRNA genes undergo substantial copy number alteration in lung cancer. The most frequently amplified miRNA genes include the following: miR-30d, miR-21, miR-17 and miR-155. We also showed that both DICER1 and DROSHA are frequently amplified in NSCLC. The copy number variation of DICER1 and DROSHA correlates well with their expression and survival of NSCLC and other cancer patients. The increased expression of DROSHA and DICER1 decreases and increases the survival, respectively. In conclusion, our results show that copy number variation may be an important mechanism of upregulation/downregulation of miRNAs in cancer and suggest an oncogenic role for DROSHA.

The modulation of Dicer regulates tumor immunogenicity in melanoma

MicroRNAs (miRs) are small non-coding RNAs that regulate most cellular protein networks by targeting mRNAs for translational inhibition or degradation. Dicer, a type III endoribonuclease, is a critical component in microRNA biogenesis and is required for mature microRNA production. Abnormal Dicer expression occurs in numerous cancer types and correlates with poor patient prognosis. For example, increased Dicer expression in melanoma is associated with more aggressive tumors (higher tumor mitotic index and depth of invasion) and poor patient prognosis. However, the role that Dicer plays in melanoma development and immune evasion remains unclear. Here, we report on a newly discovered relationship between Dicer expression and tumor immunogenicity. To investigate Dicer's role in regulating melanoma immunogenicity, Dicer knockdown studies were performed. We found that B16F0-Dicer deficient cells exhibited decreased tumor growth compared to control cells and were capable of inducing anti-tumor immunity. The decrease in tumor growth was abrogated in immunodeficient NSG mice and was shown to be dependent upon CD8⁺ T cells. Dicer knockdown also induced a more responsive immune gene profile in melanoma cells. Further studies demonstrated that CD8⁺ T cells preferentially killed Dicer knockdown tumor cells compared to control cells. Taken together, we present evidence which links Dicer expression to tumor immunogenicity in melanoma.

Identification of host transcriptional networks showing concentration-dependent regulation by HPV16 E6 and E7 proteins in basal cervical squamous epithelial cells

Development of cervical squamous cell carcinoma requires increased expression of the major high-risk human-papillomavirus (HPV) oncogenes E6 and E7 in basal cervical epithelial cells. We used a systems biology approach to identify host transcriptional networks in such cells and study the concentration-dependent changes produced by HPV16-E6 and -E7 oncoproteins. We investigated sample sets derived from the W12 model of cervical neoplastic progression, for which high quality phenotype/genotype data were available. We defined a gene co-expression matrix containing a small number of highly-connected hub nodes that controlled large numbers of downstream genes (regulons), indicating the scale-free nature of host gene co-expression in W12. We identified a small number of ‘master regulators’ for which downstream effector genes were significantly associated with protein levels of HPV16 E6 (n = 7) or HPV16 E7 (n = 5). We validated our data by depleting E6/E7 in relevant cells and by functional analysis of selected genes in vitro. We conclude that the network of transcriptional interactions in HPV16-infected basal-type cervical epithelium is regulated in a concentration-dependent manner by E6/E7, via a limited number of central master-regulators. These effects are likely to be significant in cervical carcinogenesis, where there is competitive selection of cells with elevated expression of virus oncoproteins.

Overexpression of the oncostatin-M receptor in cervical squamous cell carcinoma is associated with epithelial-mesenchymal transition and poor overall survival

Background:

Copy-number gain of the oncostatin-M receptor (OSMR) occurs frequently in cervical squamous cell carcinoma (SCC) and is associated with adverse clinical outcome. We previously showed that OSMR overexpression renders cervical SCC cells more sensitive to the major ligand oncostatin-M (OSM), which increases migration and invasion in vitro. We hypothesised that a major contribution to this phenotype would come from epithelial–mesenchymal transition (EMT).

Methods:

We performed a comprehensive integrated study, involving in vitro cell line studies, in vivo animal models and numerous clinical samples from a variety of anatomical sites.

Results:

In independent sets of cervical, head/neck and lung SCC tissues, OSMR expression levels correlated with multiple EMT-associated phenotypic markers and transcription factors. OSM treatment of OSMR overexpressing cervical SCC cells produced consistent EMT changes and increased tumour sphere formation in suspension culture. In a mouse model, OSMR overexpressing SCC cells treated with OSM showed significant increases in lung colonisation. The biological effects of exogenous OSM were mirrored by highly significant adverse overall survival in cervical SCCs with OSMR overexpression (N=251).

Conclusions:

OSM:OSMR interactions are able to induce EMT, increased cancer stem cell-like properties and enhanced lung colonisation in SCC cells. These changes are likely to contribute to the highly significant adverse outcome associated with OSMR overexpression in cervical SCCs.

Noncoding RNAs: New Players in Cancers

The world of noncoding RNAs (ncRNAs) has gained widespread attention in recent years due to their novel and crucial potency of biological regulation. Noncoding RNAs play essential regulatory roles in a broad range of developmental processes and diseases, notably human cancers. Regulatory ncRNAs represent multiple levels of structurally and functionally distinct RNAs, including the best-known microRNAs (miRNAs), the complicated long ncRNAs (lncRNAs), and the newly identified circular RNAs (circRNAs). However, the mechanisms by which they act remain elusive. In this chapter, we will review the current knowledge of the ncRNA field, discussing the genomic context, biological functions, and mechanisms of action of miRNAs, lncRNAs, and circRNAs. We also highlight the implications of the biogenesis and gene expression dysregulation of different ncRNA subtypes in the initiation and development of human malignancies.

Dysregulation of microRNA biogenesis machinery in cancer

MicroRNAs (miRNAs) are integral to the gene regulatory network. A single miRNA is capable of controlling the expression of hundreds of protein coding genes and modulate a wide spectrum of biological functions, such as proliferation, differentiation, stress responses, DNA repair, cell adhesion, motility, inflammation, cell survival, senescence and apoptosis, all of which are fundamental to tumorigenesis. Overexpression, genetic amplification, and gain-of-function mutation of oncogenic miRNAs ("onco-miRs") as well as genetic deletion and loss-of-function mutation of tumor suppressor miRNAs ("suppressor-miRs") are linked to human cancer. In addition to the dysregulation of a specific onco-miR or suppressor-miRs, changes in global miRNA levels resulting from a defective miRNA biogenesis pathway play a role in tumorigenesis. The function of individual onco-miRs and suppressor-miRs and their target genes in cancer has been described in many different articles elsewhere. In this review, we primarily focus on the recent development regarding the dysregulation of the miRNA biogenesis pathway and its contribution to cancer.

MicroRNA biogenesis pathways in cancer

MicroRNAs (miRNAs) are critical regulators of gene expression. Amplification and overexpression of individual 'oncomiRs' or genetic loss of tumour suppressor miRNAs are associated with human cancer and are sufficient to drive tumorigenesis in mouse models. Furthermore, global miRNA depletion caused by genetic and epigenetic alterations in components of the miRNA biogenesis machinery is oncogenic. This, together with the recent identification of novel miRNA regulatory factors and pathways, highlights the importance of miRNA dysregulation in cancer.

Meta-analysis of microRNA expression profiling studies in human cervical cancer

Cervical cancer is one of the most common malignant tumors in women, and numerous studies have associated the disease with changes in microRNA (miRNA) expression. This meta-analysis aimed to consolidate and assess the results of these studies in order to identify potential miRNA biomarkers of cervical cancer. We systematically searched the literature for studies comparing miRNA expression between cervical cancer tissues and normal cervical tissues, and we meta-analyzed the result of 27 studies comprising 1,132 cancer samples and 943 normal samples. We used a vote-counting strategy that took into account total sample and mean fold-change, in order to comprehensively assess associations between certain miRNAs and cervical cancer occurrence and progression. The studies described 195 miRNAs that were significantly up-regulated and 96 microRNAs that were down-regulated in cervical cancer tissues (stage I-IV) relative to normal cervical tissues. Vote-counting analysis showed that up-regulation was most consistently reported for miR-20a and miR-21 (four studies), followed by miR-10a, miR-15b, miR-20b, miR-141, miR-200a, and miR-224 (three studies). Down-regulation was reported most consistently for miR-143 (seven studies), followed by miR-203 and miR-145 (six studies). Fourteen miRNA, respectively, showed a significantly correlated lymphatic node metastasis in eight studies. This meta-analysis has identified several miRNAs whose expression correlates reliably with cervical cancer. These should be probed in further studies to explore their potential as diagnostic biomarkers.

Pathogenesis of human papillomavirus-associated mucosal disease

Human papillomaviruses (HPVs) are a necessary cause of carcinoma of the cervix and other mucosal epithelia. Key events in high-risk HPV (HRHPV)-associated neoplastic progression include persistent infection, deregulated expression of virus early genes in basal epithelial cells and genomic instability causing secondary host genomic imbalances. There are multiple mechanisms by which deregulated virus early gene expression may be achieved. Integration of virus DNA into host chromosomes is observed in the majority of cervical squamous cell carcinomas (SCCs), although in ∼15% of cases the virus remains extrachromosomal (episomal). Interestingly, not all integration events provide a growth advantage to basal cervical epithelial cells or lead to increased levels of the virus oncogenes E6 and E7, when compared with episome-containing basal cells. The factors that provide a competitive advantage to some integrants, but not others, are complex and include virus and host contributions. Gene expression from integrated and episomal HRHPV is regulated through host epigenetic mechanisms affecting the virus long control region (LCR), which appear to be of functional importance. New approaches to treating HRHPV-associated mucosal neoplasia include knockout of integrated HRHPV DNA, depletion of virus transcripts and inhibition of virus early gene transcription through targeting or use of epigenetic modifiers. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

MicroRNAs in virus-induced tumorigenesis and IFN system

Numerous microRNAs (miRNAs), small non-coding RNAs encoded in the human genome, have been shown to be involved in cancer pathogenesis and progression. There is evidence that some of these miRNAs possess proapoptotic or proliferation promoting roles in the cell by negatively regulating target mRNAs. Oncogenic viruses are able to produce persistent infection, favoring tumor development by deregulating cell proliferation and inhibiting apoptosis. It has been recently suggested that cellular miRNAs may participate in host-virus interactions, influencing viral replication. Many mammalian viruses counteract this cellular antiviral defense by using viral proteins but also by encoding viral miRNAs involved in virus-induced tumorigenesis. Interferons (IFNs) modulate a number of non-coding RNA genes, especially miRNAs, that may be used by mammalian organisms as a mechanism of IFN system to combat viral infection and related diseases. In particular, IFNs might induce specific cellular miRNAs that target viral transcripts thereby using this strategy as part of their effectiveness against invading viruses. Therefore IFNs, interferon stimulated genes and miRNAs could act synergistically as innate response to virus infection to induce a potent non-permissive cellular environment for virus replication and virus-induced cancer. The relevance of this reviewed research topic is clearly related to the observation that although virus infections are responsible of specific tumors, other unidentified genetic alterations are likely involved in the induction of malignant transformation. The identification of such genetic alterations, i.e. miRNA expression in transformed cells, would be of considerable importance for the analysis of the pathogenesis and for the treatment of cancer induced by specific viruses as well as for the advancement of the current knowledge on the molecular mechanisms underlying virus-host interaction. In this respect, we will review also the important, still little explored, roles of miRNAs acting both as IFN-stimulated anti-viral molecules and as critical regulators of IFNs and IFN-stimulated genes.

Multistep model of cervical cancer: participation of miRNAs and coding genes

Aberrant miRNA expression is well recognized as an important step in the development of cancer. Close to 70 microRNAs (miRNAs) have been implicated in cervical cancer up to now, nevertheless it is unknown if aberrant miRNA expression causes the onset of cervical cancer. One of the best ways to address this issue is through a multistep model of carcinogenesis. In the progression of cervical cancer there are three well-established steps to reach cancer that we used in the model proposed here. The first step of the model comprises the gene changes that occur in normal cells to be transformed into immortal cells (CIN 1), the second comprises immortal cell changes to tumorigenic cells (CIN 2), the third step includes cell changes to increase tumorigenic capacity (CIN 3), and the final step covers tumorigenic changes to carcinogenic cells. Altered miRNAs and their target genes are located in each one of the four steps of the multistep model of carcinogenesis. miRNA expression has shown discrepancies in different works; therefore, in this model we include miRNAs recording similar results in at least two studies. The present model is a useful insight into studying potential prognostic, diagnostic, and therapeutic miRNAs.

A Comprehensive Review of Dysregulated miRNAs Involved in Cervical Cancer

MicroRNAs(miRNAs) have become the center of interest in oncology. In recent years, various studies have demonstrated that miRNAs regulate gene expression by influencing important regulatory genes and thus are responsible for causing cervical cancer. Cervical cancer being the third most diagnosed cancer among the females worldwide, is the fourth leading cause of cancer related mortality. Prophylactic human papillomavirus (HPV) vaccines and new HPV screening tests, combined with traditional Pap test screening have greatly reduced cervical cancer. Yet, thousands of women continue to be diagnosed with and die of this preventable disease annually. This has necessitated the scientists to ponder over ways of evolving new methods and chalk out novel treatment protocols/strategies. As miRNA deregulation plays a key role in malignant transformation of cervical cancer along with its targets that can be exploited for both prognostic and therapeutic strategies, we have collected and reviewed the role of miRNA in cervical cancer. A systematic search was performed using PubMed for articles that report aberrant expression of miRNA in cervical cancer. The present review provides comprehensive information for 246 differentially expressed miRNAs gathered from 51 published articles that have been implicated in cervical cancer progression. Of these, more than 40 miRNAs have been reported in the literature in several instances signifying their role in the regulation of cancer. We also identified 40 experimentally validated targets, studied the cause of miRNAs dysregulation along with its mechanism and role in different stages of cervical cancer. We also identified and analysed miRNA clusters and their expression pattern in cervical cancer. This review is expected to further enhance our understanding in this field and serve as a valuable reference resource.

Clinical implications of (epi)genetic changes in HPV-induced cervical precancerous lesions

Infection of cervical epithelium with high-risk human papilloma virus (hrHPV) might result in productive or transforming cervical intraepithelial neoplasia (CIN) lesions, the morphology of which can overlap. In transforming CIN lesions, aberrations in host cell genes accumulate over time, which is necessary for the ultimate progression to cancer. On the basis of (epi)genetic changes, early and advanced transforming CIN lesions can be distinguished. This paves the way for new molecular tools for cervical screening, diagnosis and management of cervical cancer precursor lesions.

MicroRNA Machinery Genes as Novel Biomarkers for Cancer

MicroRNAs (miRNAs) directly and indirectly affect tumorigenesis. To be able to perform their myriad roles, miRNA machinery genes, such as Drosha, DGCR8, Dicer1, XPO5, TRBP, and AGO2, must generate precise miRNAs. These genes have specific expression patterns, protein-binding partners, and biochemical capabilities in different cancers. Our preliminary analysis of data from The Cancer Genome Atlas consortium on multiple types of cancer revealed significant alterations in these miRNA machinery genes. Here, we review their biological structures and functions with an eye toward understanding how they could serve as cancer biomarkers.

Oncostatin M receptor is a novel therapeutic target in cervical squamous cell carcinoma

Cervical carcinoma is the second most common cause of cancer deaths in women worldwide. Treatments have not changed for decades and survival rates for advanced disease remain low. An exciting new molecular target for the treatment of cervical squamous cell carcinoma (SCC), and possibly for SCCs at other anatomical sites, is the oncostatin M receptor (OSMR). This cell surface cytokine receptor is commonly copy number gained and overexpressed in advanced cervical SCC, changes that are associated with significantly worse clinical outcomes. OSMR overexpression in cervical SCC cells results in enhanced responsiveness to the major ligand oncostatin M (OSM), which induces several pro-malignant effects, including a pro-angiogenic phenotype and increased cell migration and invasiveness. OSMR is a strong candidate for antibody-mediated inhibition, a strategy that has had a major impact on haematological malignancies and various solid tumours such as HER2-positive breast cancers.

Smoking and microRNA dysregulation: a cancerous combination

MicroRNAs (miRNAs) are post-transcriptional gene regulators that are differentially expressed in several pathophysiological conditions including cancer. They impact the disease course by modulating an array of putative target gene(s). Interestingly, there is a strong correlation between the various miRNAs target(s) and the smoking-regulated genes in cancer. This review article provides an insight into the current status of smoking-induced miRNAs and their genetic/epigenetic regulation in smoking-associated cancers, with a major focus on lung cancer (LC). Furthermore, it discusses the role of miRNAs in smoking-mediated oncogenic events in cancer and explores the diagnostic/prognostic potential of miRNA-based biomarkers and their efficacy as therapeutic targets.

Tissue transglutaminase mediates the pro-malignant effects of oncostatin M receptor over-expression in cervical squamous cell carcinoma

Oncostatin M receptor (OSMR) is commonly over-expressed in advanced cervical squamous cell carcinoma (SCC), producing a significantly worse clinical outcome. Cervical SCC cells that over-express OSMR show enhanced responsiveness to the major ligand OSM, which induces multiple pro-malignant effects, including increased cell migration and invasiveness. Here, we show that tissue transglutaminase (TGM2) is an important mediator of the ligand-dependent phenotypic effects of OSMR over-expression in SCC cells. TGM2 expression correlated with disease progression and with OSMR levels in clinical samples of cervical and oral SCC. TGM2 depletion in cervical SCC cells abrogated OSM-induced migration on fibronectin-coated surfaces and invasiveness through extracellular matrix, while ectopic expression of TGM2 increased cell motility and invasiveness. Confocal microscopy and co-immunoprecipitation assays showed that TGM2 interacted with integrin-α5β1 in the presence of fibronectin in cervical SCC cells, with OSM treatment strengthening the interaction. Importantly, integrin-α5β1 and fibronectin were also over-expressed in cervical and oral SCC, where levels correlated with those of OSMR and TGM2. This combined tissue and in vitro study demonstrates for the first time that stimulation of over-expressed OSMR in cervical SCC cells activates TGM2/integrin-α5β1 interactions and induces pro-malignant changes. We conclude that an OSMR/TGM2/integrin-α5β1/fibronectin pathway is of biological significance in cervical SCC and a candidate for therapeutic targeting.

Defective DROSHA processing contributes to downregulation of MiR-15/-16 in chronic lymphocytic leukemia

The MIR-15A/-16-1 tumor suppressor microRNAs (miRNAs) are deleted in leukemic cells from more than 50% of patients with chronic lymphocytic leukemia (CLL). As these miRNAs are also less abundant in patients without genomic deletion, their downregulation in CLL is likely to be caused by additional mechanisms. We found the primary transcripts (pri-miRNAs) of MIR-15a/-16/-15b to be elevated and processing intermediates (precursor miRNAs) to be reduced in cells from CLL patients (22/38) compared with non-malignant B-cells (n=14), indicating a block of miRNA maturation at the DROSHA processing step. Using a luciferase reporter assay for pri-miR processing we validated the defect in primary CLL cells. The block of miRNA maturation is restricted to specific miRNAs and can be found in the cell line MEC-2, but not in MEC-1, even though both are derived from the same CLL patient. In these cells, the RNA-specific deaminase ADARB1 leads to reduced pri-miRNA processing, but full processing efficiency is recovered upon deletion of the RNA-binding domains or nuclear localization of ADARB1. Thus, we show that, apart from genomic deletion or transcriptional downregulation, aberrant processing of miRNA leads to specific reduction of miRNAs in leukemic cells. This represents a novel oncogenic mechanism in the pathogenesis of CLL.