Deregulation of microRNAs Let-7a and miR-21 mediate aberrant STAT3 signaling during human papillomavirus-induced cervical carcinogenesis: role of E6 oncoprotein

Prognostic and therapeutic potential of STAT3: Opportunities and challenges in targeting HPV-mediated cervical carcinogenesis

Cervical cancer (CaCx) ranks as the fourth most prevalent cancer among women globally. Persistent infection of high-risk human papillomaviruses (HR-HPVs) is major etiological factor associated with CaCx. Signal Transducer and Activator of Transcription 3 (STAT3), a prominent member of the STAT family, has emerged as independent oncogenic driver. It is a target of many oncogenic viruses including HPV. How STAT3 influences HPV viral gene expression or gets affected by HPV is an area of active investigation. A better understanding of host-virus interaction will provide a prognostic and therapeutic window for CaCx control and management. In this comprehensive review, we delve into carcinogenic role of STAT3 in development of HPV-induced CaCx. With an emphasis on fascinating interplay between STAT3 and HPV genome, the review explores the diverse array of opportunities and challenges associated with this field to harness the prognostic and therapeutic potential of STAT3 in CaCx.

Critical role of miR-21/exosomal miR-21 in autophagy pathway

Activation of autophagy, a process of cellular stress response, leads to the breakdown of proteins, organelles, and other parts of the cell in lysosomes, and can be linked to several ailments, such as cancer, neurological diseases, and rare hereditary syndromes. Thus, its regulation is very carefully monitored. Transcriptional and post-translational mechanisms domestically or in whole organisms utilized to control the autophagic activity, have been heavily researched. In modern times, microRNAs (miRNAs) are being considered to have a part in post-translational orchestration of the autophagic activity, with miR-21 as one of the best studied miRNAs, it is often more than expressed in cancer cells. This regulatory RNA is thought to play a major role in a plethora of processes and illnesses including growth, cancer, cardiovascular disease, and inflammation. Different studies have suggested that a few autophagy-oriented genes, such as PTEN, Rab11a, Atg12, SIPA1L2, and ATG5, are all targeted by miR-21, indicating its essential role in the regulation.

Regulatory Non-Coding RNAs during Porcine Viral Infections: Potential Targets for Antiviral Therapy

Pigs play important roles in agriculture and bio-medicine; however, porcine viral infections have caused huge losses to the pig industry and severely affected the animal welfare and social public safety. During viral infections, many non-coding RNAs are induced or repressed by viruses and regulate viral infection. Many viruses have, therefore, developed a number of mechanisms that use ncRNAs to evade the host immune system. Understanding how ncRNAs regulate host immunity during porcine viral infections is critical for the development of antiviral therapies. In this review, we provide a summary of the classification, production and function of ncRNAs involved in regulating porcine viral infections. Additionally, we outline pathways and modes of action by which ncRNAs regulate viral infections and highlight the therapeutic potential of artificial microRNA. Our hope is that this information will aid in the development of antiviral therapies based on ncRNAs for the pig industry.

Physical interaction between STAT3 and AP1 in cervical carcinogenesis: Implications in HPV transcription control

The constitutive activation and aberrant expression of Signal Transducer and Activator of Transcription 3 (STAT3) plays a key role in initiation and progression of cervical cancer (CaCx). How STAT3 influences HPV transcription is poorly defined. In the present study, we probed direct and indirect interactions of STAT3 with HPV16/18 LCR. In silico assessment of cis-elements present on LCR revealed the presence of potential STAT3 binding motifs. However, experimental validation by ChIP-PCR could not confirm any specific STAT3 binding on HPV16 LCR. Protein-protein interaction (PPI) network analysis of STAT3 with other host transcription factors that bind LCR, highlighted the physical association of STAT3 with c-FOS and c-JUN. This was further confirmed in vitro by co-immunoprecipitation, where STAT3 co-immunoprecipitated with c-FOS and c-JUN in CaCx cells. The result was supported by immunocytochemical analysis and colocalization of STAT3 with c-FOS and c-JUN. Positive signals in proximity ligation assay validated physical interaction and colocalization of STAT3 with AP1. Colocalization of STAT3 with c-FOS and c-JUN increased upon IL-6 treatment and decreased post-Stattic treatment. Alteration of STAT3 expression affected the subcellular localization of c-FOS and c-JUN, along with the expression of viral oncoproteins (E6 and E7) in CaCx cells. High expression of c-JUN in tumor tissues correlated with poor prognosis in both HPV16 and HPV18 CaCx cohort whereas high expression of STAT3 correlated with poor prognosis in HPV18 CaCx lesions only. Overall, the data suggest an indirect interaction of STAT3 with HPV LCR via c-FOS and c-JUN and potentiate transcription of viral oncoproteins.

Revisiting the role of endogenous STAT3 in HPV-positive cervical cancer cells

Novel treatment options for human papillomavirus (HPV)-induced cancers are urgently required. The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is considered to be constitutively active in HPV-positive cervical cancer cells and essential for their proliferation. Moreover, STAT3 was reported to undergo mutually stimulatory interactions with the HPV E6/E7 oncogenes. Thus, inhibiting STAT3 in HPV-positive cancer cells is under discussion to provide a powerful novel therapeutic strategy. We here show that the antifungal drug ciclopirox destabilizes the STAT3 protein by acting as an iron chelator. However, by exploring the functional consequences of STAT3 inhibition in HPV-positive cancer cells, we obtained several unexpected results. Chemical STAT3 inhibitors heterogeneously affect cervical cancer cell proliferation and those which act antiproliferative also block the growth of STAT3 knockout cells, indicating induction of off-target effects. In contrast to several chemical inhibitors, genetic inhibition of STAT3 expression by either RNA interference or the CRISPR/Cas9 method does not appreciably affect cervical cancer cell proliferation. Transcriptome analyses indicate that blocking STAT3 expression in HPV-positive cancer cells has very limited effects on putative STAT3 target genes. Although the targeted inhibition of specific growth-promoting signaling pathways leads to a feedback activation of STAT3 in cervical cancer cells via Janus kinase 1/2, this does not lead to treatment resistance. Moreover, we did not obtain experimental evidence for a STAT3-linked activation of HPV E6/E7 oncogene expression or, vice versa, an E6/E7-dependent activation of STAT3, at endogenous conditions in cervical cancer cells. Collectively, these findings question the essential role of STAT3 in cervical cancer cell proliferation and the strategy to inhibit STAT3 in these cells for therapeutic purposes.

MicroRNA-21 in gynecological cancers: From molecular pathogenesis to clinical significance

Ovarian, cervical, and endometrial cancers are the three most common gynecological cancer types (GCs). They hold a significant position as the leading causes of mortality among women with cancer-related death. However, GCs are often diagnosed late, severely limiting the efficacy of current treatment options. Thus, there is an urgent, unmet need for innovative experimentation to enhance the clinical treatment of GC patients. MicroRNAs (miRNAs) are a large and varied class of short noncoding RNAs (22 nucleotides in length) that have been shown to play essential roles in various biological processes involved in development. Recent research has shown that miR-211 influences tumorigenesis and cancer formation, adding to our knowledge of the miR-21 dysregulation in GCs. Furthermore, current research that sheds light on the crucial functions of miR-21 may provide supporting evidence for its potential prognostic, diagnostic, and therapeutic applications in the context of GCs. This review will thus focus on the most recent findings concerning miR-21 expression, miR-21 target genes, and the processes behind GCs. In addition, the latest findings that support miR-21's potential use as a non-invasive biomarker and therapeutic agent for detecting and treating cancer will be elucidated in this review. The roles played by various lncRNA/circRNA-miRNA-mRNA axis in GCs are also comprehensively summarized and described in this study, along with any possible implications for how these regulatory networks may contribute to the pathogenesis of GCs. Also, it is crucial to recognize the complexity of the processes involved in tumour therapeutic resistance as a significant obstacle in treating GCs. Furthermore, this review provides an overview of the current state of knowledge regarding the functional significance miR-21 in therapeutic resistance within the context of GCs.

The HPV16 E6, E7/miR-23b-3p/ICAT signaling axis promotes proliferation, migration, invasion and EMT of cervical cancer cells

Cervical cancer (CC) remains one of the most common female malignancies, with higher incidence and mortality rates. more than 99% of CCs are associated with persistent infection with high-risk human papillomavirus. In view of the growing evidence that HPV 16 E6 and E7, two key oncoproteins encoded by HPV 16, regulate the expression of many other multifunctional genes and downstream effectors that contribute to the development of CC. Herein, we undertook a comprehensive effort into how HPV16 E6, E7 oncogenes affect the progression of CC cells. Previous studies have shown that ICAT expression was significantly increased in CC and had a pro-cancer effect. We observed that knockdown of HPV16 E6, E7 expression in SiHa and CasKi cells resulted in significant inhibition of ICAT expression and upregulation of miR-23b-3p expression. Besides, dual luciferase assays confirmed that ICAT was a target gene of miR-23b-3p, and negatively modulated by miR-23b-3p. Functional experiments showed that the overexpression of miR-23b-3p suppressed malignant behaviors of CC cells, such as migration, invasion and EMT. The overexpression of ICAT counteracted the suppressive effect of miR-23b-3p on HPV16-positive CC cells. Furthermore, after the knockdown of HPV16 E6 and E7, the inhibition of miR-23b-3p could increase the ICAT expression and rescue the siRNA HPV16 E6, E7-mediated suppressive impact on the aggressiveness of SiHa and CaSki cells. Collectively, our findings uncover that HPV16 E6, E7/miR-23b-3p/ ICAT axis plays an important role in HPV16-positive CC pathogenesis, which may serve as a promising therapeutic target for HPV16-associated CC.

Breast cancer tumor microenvironment affects Treg/IL-17-producing Treg/Th17 cell axis: Molecular and therapeutic perspectives

The tumor microenvironment (TME) comprises a variety of immune cells, among which T cells exert a prominent axial role in tumor development or anti-tumor responses in patients with breast cancer (BC). High or low levels of anti-inflammatory cytokines, such as transforming growth factor β, in the absence or presence of proinflammatory cytokines, such as interleukin-6 (IL-6), delineate the fate of T cells toward either regulatory T (Treg) or T helper 17 (Th17) cells, respectively. The transitional state of RORγt⁺Foxp3⁺ Treg (IL-17-producing Treg) resides in the middle of this reciprocal polarization, which is known as Treg/IL-17-producing Treg/Th17 cell axis. TME secretome, including microRNAs, cytokines, and extracellular vesicles, can significantly affect this axis. Furthermore, immune checkpoint inhibitors may be used to reconstruct immune cells; however, some of these novel therapies may favor tumor development. Therefore, understanding secretory and cell-associated factors involved in their differentiation or polarization and functions may be targeted for BC management. This review discusses microRNAs, cytokines, and extracellular vesicles (as secretome), as well as transcription factors and immune checkpoints (as cell-associated factors), which influence the Treg/IL-17-producing Treg/Th17 cell axis in BC. Furthermore, approved or ongoing clinical trials related to the modulation of this axis in the TME of BC are described to broaden new horizons of promising therapeutic approaches.

Pre-clinical and clinical importance of miR-21 in human cancers: Tumorigenesis, therapy response, delivery approaches and targeting agents

The field of non-coding RNA (ncRNA) has made significant progress in understanding the pathogenesis of diseases and has broadened our knowledge towards their targeting, especially in cancer therapy. ncRNAs are a large family of RNAs with microRNAs (miRNAs) being one kind of endogenous RNA which lack encoded proteins. By now, miRNAs have been well-coined in pathogenesis and development of cancer. The current review focuses on the role of miR-21 in cancers and its association with tumor progression. miR-21 has both oncogenic and onco-suppressor functions and most of the experiments are in agreement with the tumor-promoting function of this miRNA. miR-21 primarily decreases PTEN expression to induce PI3K/Akt signaling in cancer progression. Overexpression of miR-21 inhibits apoptosis and is vital for inducing pro-survival autophagy. miR-21 is vital for metabolic reprogramming and can induce glycolysis to enhance tumor progression. miR-21 stimulates EMT mechanisms and increases expression of MMP-2 and MMP-9 thereby elevating tumor metastasis. miR-21 is a target of anti-cancer agents such as curcumin and curcumol and its down-regulation impairs tumor progression. Upregulation of miR-21 results in cancer resistance to chemotherapy and radiotherapy. Increasing evidence has revealed the role of miR-21 as a biomarker as it is present in both the serum and exosomes making them beneficial biomarkers for non-invasive diagnosis of cancer.

Investigation of molecular mechanisms underlying JAK/STAT signaling pathway in HPV-induced cervical carcinogenesis using 'omics' approach

The precise mechanism of action of Janus Kinases (JAK)/Signal Transducer and activator of Transcription (STAT) signaling in human papillomavirus (HPV)-associated cervical cancer (CaCx) is poorly defined. The present study dissected the underlying components of JAK/STAT signaling in HPV-positive cervical neoplasms. Whole transcriptome profile of CaCx cohort from TCGA database revealed elevated STAT3 and its impact on CaCx patients' survival. Using the RT² Profiler PCR Array, we analyzed 84 genes of interest associated with JAK/STAT signaling in mRNA derived from HPV-negative and HPV-positive cervical lesions which revealed 21 differentially expressed genes (DEGs). Analyses of DEGs using the Database for Annotation, Visualization and Integrated Discovery tool indicated maximum genes enriched in immune response and negative regulation of apoptotic process. Protein-protein network analysis indicated IL4, STAT5A, STAT4, and JAK3 to be the key genes in the interaction network. Further, 7 key DEGs (IL4R, IRF1, EGFR, OAS1, PIAS1, STAT4, and STAT5A) were validated in TCGA cohort using R2 platform. These genes were differentially expressed among HPV-positive cervical tissues and their correlation with STAT3 was established. EGFR and IL4R showed a comparatively strong correlation with STAT3 that supports their involvement in pathogenesis of CaCx. Finally, the Kaplan-Meier analysis established the prognostic association of the key DEGs, in CaCx cohort. The STAT3 and associated key genes discovered from our study establish a strong pathogenic role of JAK/STAT3 pathway in HPV-mediated cervical carcinogenesis.

MicroRNA let-7 and viral infections: focus on mechanisms of action

MicroRNAs (miRNAs) are fundamental post-transcriptional modulators of several critical cellular processes, a number of which are involved in host defense mechanisms. In particular, miRNA let-7 functions as an essential regulator of the function and differentiation of both innate and adaptive immune cells. Let-7 is involved in several human diseases, including cancer and viral infections. Several viral infections have found ways to dysregulate the expression of miRNAs. Extracellular vesicles (EV) are membrane-bound lipid structures released from many types of human cells that can transport proteins, lipids, mRNAs, and miRNAs, including let-7. After their release, EVs are taken up by the recipient cells and their contents released into the cytoplasm. Let-7-loaded EVs have been suggested to affect cellular pathways and biological targets in the recipient cells, and can modulate viral replication, the host antiviral response, and the action of cancer-related viruses. In the present review, we summarize the available knowledge concerning the expression of let-7 family members, functions, target genes, and mechanistic involvement in viral pathogenesis and host defense. This may provide insight into the development of new therapeutic strategies to manage viral infections.

An Alternative Treatment for Vaginal Cuff Wart: a Case Report

Human papillomavirus (HPV) has been directly related to acuminate warts and cervical cancer, the second most common neoplasia among women. Given the lack of treatment against the virus itself, many medications have been utilised, mainly aiming in modifying the host's immunological response. We present the case of a 54 years old postmenopausal patient with a history of vaginal cuff wart and HPV persistence that we managed in our clinic for 6 months with a mix of curcumin, aloe vera, amla and other natural ingredients. As the patient was found to be intolerant to imiquimod (one of the most common conservative methods of treatment) we attempted the use of curcumin, which was applied to the area of the wart three times per week for 6 months. Both clinical and colposcopical improvement was noted in regular clinic visits with regression of the lesion. The outcome of this case encourages our view that curcumin should be considered as a significant treatment modality against HPV infection and acuminate warts.

Rotavirus Induces Epithelial-Mesenchymal Transition Markers by Transcriptional Suppression of miRNA-29b

Acute gastroenteritis (AGE) is a serious global health problem and has been known to cause millions of infant deaths every year. Rotavirus (RV), a member of the Reoviridae family, still majorly accounts for the AGE in children below 5 years of age in India and worldwide. The involvement of miRNAs in the pathogenesis of RV has been suggested to be of the proviral as well as the anti-viral nature. miRNAs that promote the RV pathogenesis are capable of targeting the cellular components to evade the host anti-viral strategies. On the other hand, miRNAs with anti-rotaviral properties are themselves incapacitated during the progression of the infection. The exploitation of the epithelial-mesenchymal transition (EMT) as a pro-rotaviral strategy has already been identified. Thus, miRNAs that proficiently target the intermediates of the EMT pathway may serve as anti-viral counterparts in the RV-host interactions. The role of microRNA-29b (miR-29b) in the majority of human cancers has been well demonstrated, but its significance in viral infections is yet to be elaborated. In this study, we have assessed the role of miR-29b in RV-induced EMT and RV replication. Our study on miR-29b provides evidence for the recruitment of RV non-structural protein NSP1 to control the trans-repression of miR-29b in a p53-dependent manner. The trans-repression of miR-29b modulates the EMT pathway by targeting tripartite motif-containing protein 44 (TRIM44) and cyclin E1 (CCNE1). SLUG and SNAIL transcription repressors (downstream of TRIM44 and CCNE1) regulate the expression of E-cadherin, an important marker of the EMT. Also, it is established that ectopic expression of miR-29b not only constrains the EMT pathway but also restricts RV replication. Therefore, miR-29b repression is a crucial event in the RV pathogenesis. Ectopic expression of miR-29b displays potential anti-viral properties against RV propagation.

Manipulation of JAK/STAT Signalling by High-Risk HPVs: Potential Therapeutic Targets for HPV-Associated Malignancies

Human papillomaviruses (HPVs) are small, DNA viruses that cause around 5% of all cancers in humans, including almost all cervical cancer cases and a significant proportion of anogenital and oral cancers. The HPV oncoproteins E5, E6 and E7 manipulate cellular signalling pathways to evade the immune response and promote virus persistence. The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway has emerged as a key mediator in a wide range of important biological signalling pathways, including cell proliferation, cell survival and the immune response. While STAT1 and STAT2 primarily drive immune signalling initiated by interferons, STAT3 and STAT5 have widely been linked to the survival and proliferative potential of a number of cancers. As such, the inhibition of STAT3 and STAT5 may offer a therapeutic benefit in HPV-associated cancers. In this review, we will discuss how HPV manipulates JAK/STAT signalling to evade the immune system and promote cell proliferation, enabling viral persistence and driving cancer development. We also discuss approaches to inhibit the JAK/STAT pathway and how these could potentially be used in the treatment of HPV-associated disease.

MicroRNA Involvement in Signaling Pathways During Viral Infection

The study of miRNAs started in 1993, when Lee et al. observed their involvement in the downregulation of a crucial protein known as LIN-14 in the nematode Caenorhabditis elegans. Since then, great progress has been made regarding research on microRNAs, which are now known to be involved in the regulation of various physiological and pathological processes in both animals and humans. One such example is represented by their interaction with various signaling pathways during viral infections. It has been observed that these pathogens can induce the up-/downregulation of various host miRNAs in order to elude the host's immune system. In contrast, some miRNAs studied could have an antiviral effect, enabling the defense mechanisms to fight the infection or, at the very least, they could induce the pathogen to enter a latent state. At the same time, some viruses encode their own miRNAs, which could further modulate the host's signaling pathways, thus favoring the survival and replication of the virus. The goal of this extensive literature review was to present how miRNAs are involved in the regulation of various signaling pathways in some of the most important and well-studied human viral infections. Further on, knowing which miRNAs are involved in various viral infections and what role they play could aid in the development of antiviral therapeutic agents for certain diseases that do not have a definitive cure in the present. The clinical applications of miRNAs are extremely important, as miRNAs targeted inhibition may have substantial therapeutic impact. Inhibition of miRNAs can be achieved through many different methods, but chemically modified antisense oligonucleotides have shown the most prominent effects. Though scientists are far from completely understanding all the molecular mechanisms behind the complex cross-talks between miRNA pathways and viral infections, the general knowledge is increasing on the different roles played by miRNAs during viral infections.

The Interplay between Antiviral Signalling and Carcinogenesis in Human Papillomavirus Infections

Human papillomaviruses (HPV) are the causative agents of the most common sexually transmitted infection worldwide. While infection is generally asymptomatic and can be cleared by the host immune system, when persistence occurs, HPV can become a risk factor for malignant transformation. Progression to cancer is actually an unintended consequence of the complex HPV life cycle. Different antiviral defence mechanisms recognize HPV early in infection, leading to the activation of the innate immune response. However, the virus has evolved several specific strategies to efficiently evade the antiviral immune signalling. Here, we review and discuss the interplay between HPV and the host cell innate immunity. We further highlight the evasion strategies developed by different HPV to escape this cellular response and focus on the correlation with HPV-induced persistence and tumorigenesis.

Human Papillomavirus Infections, Cervical Cancer and MicroRNAs: An Overview and Implications for Public Health

Human Papillomavirus (HPV) is among the most common sexually transmitted infections in both females and males across the world that generally do not cause symptoms and are characterized by high rates of clearance. Persistent infections due at least to twelve well-recognized High-Risk (HR) or oncogenic genotypes, although less frequent, can occur, leading to diseases and malignancies, principally cervical cancer. Three vaccination strategies are currently available for preventing certain HR HPVs-associated diseases, infections due to HPV6 and HPV11 low-risk types, as well as for providing cross-protection against non-vaccine genotypes. Nevertheless, the limited vaccine coverage hampers reducing the burden of HPV-related diseases globally. For HR HPV types, especially HPV16 and HPV18, the E6 and E7 oncoproteins are needed for cancer development. As for other tumors, even in cervical cancer, non-coding microRNAs (miRNAs) are involved in posttranscriptional regulation, resulting in aberrant expression profiles. In this study, we provide a summary of the epidemiological background for HPV occurrence and available immunization programs. In addition, we present an overview of the most relevant evidence of miRNAs deregulation in cervical cancer, underlining that targeting these biomolecules could lead to wide translational perspectives, allowing better diagnosis, prognosis and therapeutics, and with valuable applications in the field of prevention. The literature on this topic is rapidly growing, but advanced investigations are required to achieve more consistent findings on the up-regulated and down-regulated miRNAs in cervical carcinogenesis. Because the expression of miRNAs is heterogeneously reported, it may be valuable to assess factors and risks related to individual susceptibility.

Prediction of a miRNA-mRNA functional synergistic network for cervical squamous cell carcinoma

Cervical squamous cell carcinoma (CSCC) accounts for a significant proportion of cervical cancer; thus, there is a need for novel and noninvasive diagnostic biomarkers for this malignancy. In this study, we performed integrated analysis of a dataset from the Gene Expression Omnibus database to identify differentially expressed genes (DEGs) and differentially expressed miRNAs (DEmiRNAs) between CSCC, cervical intraepithelial neoplasia (CIN) and healthy control subjects. We further established protein-protein interaction and DEmiRNA-target gene interaction networks, and performed functional annotation of the target genes of DEmiRNAs. In total, we identified 1375 DEGs and 19 DEmiRNAs in CIN versus normal control, and 2235 DEGs and 33 DEmiRNAs in CSCC versus CIN by integrated analysis. Our protein-protein interaction network indicates that the common DEGs, Cyclin B/cyclin-dependent kinase 1 (CDK1), CCND1, ESR1 and Aurora kinase A (AURKA), are the top four hub genes. P53 and prostate cancer were identified as significantly enriched signaling pathways of common DEGs and DEmiRNA targets, respectively. We validated that expression levels of three DEGs (TYMS, SASH1 and CDK1) and one DEmiRNA of hsa-miR-99a were altered in blood samples of patients with CSCC. In conclusion, a total of four DEGs (TYMS, SASH1, CDK1 and AURKA) and two DEmiRNAs (hsa-miR-21 and hsa-miR-99a) may be involved in the pathogenesis of CIN and the progression of CIN into CSCC. Of these, TYMS is predicted to be regulated by hsa-miR-99a and SASH1 to be regulated by hsa-miR-21.

Level of phospho-STAT3 (Tyr705) correlates with copy number and physical state of human papillomavirus 16 genome in cervical precancer and cancer lesions

Our earlier studies indicated an important role of inducible transcription factor STAT3 in the establishment of persistent infection of human papillomavirus (HPV) type 16 and promotion of cervical carcinogenesis. Since HPV load and its physical state are two potential determinants of this virally-induced carcinogensis, though with some exceptions, we extended our study to examine the role of active STAT3 level in cervical precancer and cancer lesions and it’s association with HPV viral load and physical state. An elevated level of active STAT3 was measured by assessing phospho-STAT3-Y705 (pSTAT3), in tumor tissues harboring higher viral load irrespective of the disease grade. Physical state analysis of HPV16 by assessing the degree of amplification of full length E2 and comparing it with E6 (E2:E6 ratio), which predominantly represent episomal form of HPV16, revealed low or undetectable pSTAT3. A strong pSTAT3 immunoreactivity was found in tissues those harbored either mixed or predominantly integrated form of viral genome. Cumulative analysis of pSTAT3 expression, viral load and physical state demonstrated a direct correlation between pSTAT3 expression, viral load and physical state of HPV. The study suggests that there exists a strong clinical correlation between level of active STAT3 expression and HPV genome copy number, and integrated state of the virus that may play a pivotal role in promotion/maintanence of tumorigenic phenotype.

Transregulation of microRNA miR-21 promoter by AP-1 transcription factor in cervical cancer cells

BACKGROUND

Gene expression profiles have demonstrated that miR-21 expression is altered in almost all types of cancers and it has been classified as an oncogenic microRNA. Persistent HPV infection is the main etiologic agent in cervical cancer and induces genetic instability, including disruption of microRNA gene expression. In the present study, we analyzed the underlying mechanism of how AP-1 transcription factor can active miR-21 gene expression in cervical cancer cells.

METHODS

To identify that c-Fos and c-Jun regulate the expression of miR-21 we performed RT-qPCR and western blot assays. We analyzed the interaction of AP-1 with miR-21 promoter by EMSA and ChIP assays and determined the mechanism of its regulation by reporter construct plasmids. We identified the nuclear translocation of c-Fos and c-Jun by immunofluorescence microscopy assays.

RESULTS

We demonstrated that c-Fos and c-Jun proteins are expressed and regulate the expression of miR-21 in cervical cancer cells. DNA sequence analysis revealed the presence of AP-1 DNA-binding sites in the human miR-21 promoter region. EMSA analyses confirmed the interactions of the miR-21 upstream transcription factor AP-1. ChIP assays further showed the binding of c-Fos to AP-1 sequences from the miR-21 core promoter in vivo. Functional analysis of AP-1 sequences of miR-21 in reporter plasmids demonstrated that these sequences increase the miR-21 promoter activation.

CONCLUSIONS

Our findings suggest a physical interaction and functional cooperation between AP-1 transcription factor in the miR-21 promoter and may explain the effect of AP-1 on miR-21 gene expression in cervical cancer cells.

Long non-coding RNA MEG3 inhibits cervical cancer cell growth by promoting degradation of P-STAT3 protein via ubiquitination

Background

Maternally expressed 3 (MEG3) plays an important role in cervical cancer development, but its exact role remains unclear. Here, we explored the specific regulatory mechanism of MEG3 and its downstream proteins in cervical cancer cells.

Methods

The effect of MEG3 on tumor formation ability of cervical cancer cells was determined in nude mice. The direct binding of MEG3 to phosphorylated signal transducer and activator of transcription 3 (P-STAT3) was detected by RNA pull-down and RNA-binding protein immunoprecipitation (RIP) assays. Cycloheximide (CHX)-chase and ubiquitination assays were performed to determine the regulatory effect of MEG3 on P-STAT3 ubiquitination. Clone formation assay and flow cytometry were used to evaluate the effect of the MEG3-STAT3 regulatory axis on cell proliferation and apoptosis.

Results

In vivo tumor formation experiments showed that MEG3 inhibited the tumor formation ability of cervical cancer cells. RNA pull-down and RIP assays demonstrated that MEG3 bound directly to P-STAT3 protein. CHX-chase and ubiquitination assay results showed that MEG3 promoted P-STAT3 degradation via ubiquitination. Clone formation assay and flow cytometry analysis results revealed that the inhibitory effect of MEG3 on P-STAT3 promoted apoptosis and inhibited proliferation of cervical cancer cells.

Conclusion

MEG3 binds to P-STAT3 in cervical cancer cells, resulting in P-STAT3 ubiquitination and degradation and apoptosis and inhibition of proliferation of tumor cells. The in-depth elaboration of the MEG3-STAT3 regulatory axis in cervical cancer may clarify the mechanism of action of MEG3 and provide new ideas for cervical cancer treatment.

microRNAs: New prognostic, diagnostic, and therapeutic biomarkers in cervical cancer

Cervical cancer is as a kind of cancer beginning from the cervix. Given that cervical cancer could be observed in women who infected with papillomavirus, regular oral contraceptives, and multiple pregnancies. Early detection of cervical cancer is one of the most important aspects of the therapy of this malignancy. Despite several efforts, finding and developing new biomarkers for cervical cancer diagnosis are required. Among various prognostic, diagnostic, and therapeutic biomarkers, miRNA have been emerged as powerful biomarkers for detection, treatment, and monitoring of response to therapy in cervical cancer. Here, we summarized various miRNAs as an employable platform for prognostic, diagnostic, and therapeutic biomarkers in the treatment of cervical cancer.

Loss of miR-143 and miR-145 in condyloma acuminatum promotes cellular proliferation and inhibits apoptosis by targeting NRAS

The expression profile of miRNAs and their function in condyloma acuminatum (CA) remains unknown. In this study, we aimed to detect the effects of miR-143 and miR-145, the most downregulated in CA samples using high-throughput sequencing, on cell proliferation and apoptosis, to determine a novel therapeutic target for CA recurrence. RT-qPCR was used to validate the lower expression of miR-143 and miR-145 in a larger size of CA samples, and the expression of NRAS in CA samples was significantly higher than self-controls as determined by western blotting assay. Luciferase assay was performed to confirm that miR-143 or miR-145 targeted NRAS directly. Transduction of LV-pre-miR-143 or LV-pre-miR-145 to human papilloma virus (HPV)-infected SiHa cells led to reduced proliferation, greater apoptosis and inhibition of expression of NRAS, PI3 K p110α and p-AKT. However, knockout of miR-143 or miR-145 in human epidermal keratinocytes by delivery of CRISPR/CAS9-gRNA for target miRNAs protected cells from apoptosis and upregulated expression of target genes as described above. MiR-143 and miR-145 sensitized cells to nutlin-3a, a p53 activator and MDM2 antagonist, while their loss protected cells from the stress of nutlin-3a. Furthermore, siRNA targeting NRAS showed similar effects on proliferation and apoptosis as miR-143 or miR-145. Taken together, our results suggest that loss of miR-143 or miR-145 in CA protects HPV-infected cells from apoptosis induced by environmental stress, in addition to promoting cellular proliferation and inhibiting apoptosis by targeting NRAS/PI3 K/ATK. Restoration of miR-143 or miR-145 might provide an applicable and novel approach to block the recurrence and progression of CA.

HPV epigenetic mechanisms related to Oropharyngeal and Cervix cancers

Human Papilloma Virus infection is very frequent in humans and is mainly transmitted sexually. The majority of infections are transient and asymptomatic, however, if the infection persists, it can occur with a variety of injuries to skin and mucous membranes, depending on the type of HPV involved. Some types of HPV are classified as high oncogenic risk as associated with the onset of cancer. The tumors most commonly associated with HPV are cervical and oropharyngeal cancer, epigenetic mechanisms related to HPV infection include methylation changes to host and viral DNA and chromatin modification in host species. This review is focused about epigenethic mechanism, such as MiRNAs expression, related to cervix and oral cancer. Specifically it discuss about molecular markers associated to a more aggressive phenotype. In this way we will analyze genes involved in meiotic sinaptonemal complex, transcriptional factors, of orthokeratins, sinaptogirin, they are all expressed in cancer in a way not more dependent on cell differentiation but HPV-dependent.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Orthotopic Xenograft Mouse Model of Cervical Cancer for Studying the Role of MicroRNA-21 in Promoting Lymph Node Metastasis

Cervical cancer is the most frequent cause of gynecologic cancer-associated death worldwide. Animal models that demonstrate metastatic patterns consistent with the clinical course of cervical cancer are urgently needed to conduct studies focused on understanding the mechanisms of the disease and identifying optimal treatments. To address this, we established an orthotopic xenograft model of cervical cancer in female NOD-SCID mice using SiHa and ME180 cell lines stably expressing green fluorescent protein to evaluate the role of microRNA-21 (miR-21) in spontaneous lymph node metastasis in vivo. In this case, SiHa and ME180 cells were transduced by lentivirus to stably express green fluorescent protein and miR-21. Overexpression of miR-21 promoted proliferation, migration, and invasion of SiHa and ME180 cells in vitro. Finally, an orthotopic xenograft model of human cervical cancer was successfully established in NOD-SCID mice. Using this model, we confirmed that overexpression of miR-21 resulted in an increase in the size of primary tumors and in the frequency of spontaneous lymph node metastasis at the time of excision. Therefore, the use of the orthotopic xenograft model should allow for the investigation of novel factors that affect metastasis of cervical cancer and presents an opportunity to evaluate potential therapeutic agents that may inhibit the spread of the disease.

Dysregulation of cellular microRNAs by human oncogenic viruses - Implications for tumorigenesis

Infection with certain animal and human viruses, often referred to as tumor viruses, induces oncogenic processes in their host. These viruses can induce tumorigenesis through direct and/or indirect mechanisms, and the regulation of microRNAs expression has been shown to play a key role in this process. Some human oncogenic viruses can express their own microRNAs; however, they all can dysregulate the expression of cellular microRNAs, facilitating their respective life cycles. The modulation of cellular microRNAs expression brings consequences to the host cells that may lead to malignant transformation, since microRNAs regulate the expression of genes involved in oncogenic pathways. This review focus on the mechanisms used by each human oncogenic virus to dysregulate the expression of cellular microRNAs, and their impact on tumorigenesis.

Association between genetic polymorphisms in the promoters of let-7 and risk of cervical squamous cell carcinoma

Numerous reports showed low levels of let-7 family in cervical cancer, acting as tumor suppressors by regulating multiple target genes. Genetic variants in the promoter of miRNA have been reported to influence individuals' susceptibility to human diseases. We aimed to investigate the association of rs10877887 and rs13293512 polymorphisms in the promoters of let-7 with risk of cervical squamous cell carcinoma (CSCC). A total of 331 patients with CSCC and 358 controls were included. Genotyping of rs10877887 was done using polymerase chain reaction-restriction fragment length polymorphism analysis. Genotyping of rs13293512 was performed using Taqman allelic discrimination. Relative expression of let-7 family was determined using quantitative real-time polymerase chain reaction. The rs10877887CC genotype was significantly associated with an increased risk of CSCC compared with the rs10877887TT (adjusted OR=2.11, 95% CI, 1.31-3.40, p-value=0.002) or rs10877887 TT/CT genotypes (adjusted OR=2.11, 95% CI, 1.34-3.31, p-value<0.001). Similarly increased risk of CSCC was observed when compared rs10877887T with rs10877887C allele (adjusted OR=1.35, 95% CI, 1.08-1.69, p-value=0.008). Combined analysis showed that individuals carrying the genotypes of rs10877887CC+rs13293512CC had a 4.78-fold higher risk to develop CSCC compared with those carrying the genotypes of rs10877887CT/TT+rs13293512CT/TT (OR=4.78, 95% CI, 1.78-12.84, p-value=0.001). Additionally, patients harboring rs10877887CC genotype had a lower level of let-7i in CSCC tissues (p-value=0.02). This observation indicates that rs10877887 may be a useful biomarker for the etiology of CSCC.

DNA methylation regulated microRNAs in human cervical cancer

Regulation of miRNA gene expression by DNA promoter methylation may represent a key mechanism to drive cervical cancer progression. In order to understand the impact of DNA promoter methylation on miRNAs at various stages of cervical carcinogenesis, we performed DNA methylation microarray on Normal Cervical Epithelium (NCE), Cervical Intraepithelial Neoplasia (CIN I-III) and Squamous Cell Carcinoma (SCC) tissues to identify differentially methylated miRNAs followed by validation by bisulfite sequencing. Further, expression of miRNAs was analyzed by qRT-PCR in clinical tissues and cervical cancer cell lines. Transcriptional activity was determined by luciferase assay. We identified a total of 69 hypermethylated and hypomethylated miRNA promoters encompassing 78 CpG islands in all except Y chromosome, among the three groups. The candidate DNA promoters of miR-424 were significantly hypermethylated and miR-200b and miR-34c were significantly hypomethylated in SCC compared to NCE (P < 0.05). Expression of miR-424, miR-200b, and miR-34c were inversely correlated with promoter DNA methylation in tissue samples. Treatment of cell lines with 5-aza-2'-deoxycytidine showed differential expression in all three miRNAs. We observed a decrease in miRNA promoter activity following in vitro SssI methylase treatment of miR-424, miR-200b, and miR-34c. Luciferase assay demonstrated that miR-200b and miR-424 functionally interacts with 3'-UTR of HIPK3 and RBBP6 respectively and decreased their activity in presence of miR-200b and miR-424 mimics transfected in SiHa cells. Taken together, we have identified deregulation of miRNAs by aberrant DNA promoter methylation, leading to its transcriptional silencing during cervical carcinogenesis, which can be potential targets for diagnosis and therapy.

The relationship between microRNAs and the STAT3-related signaling pathway in cancer

MicroRNAs are non-coding RNAs that regulate gene expression by targeting messenger RNA molecules in 3' untranslated region. Mounting evidence indicates that microRNAs regulate several factors to influence various biological activities that are related to carcinogenesis, including signal transducer and activator of transcription 3, which is a transcription factor that also acts as an oncogene. MicroRNAs influence signal transducer and activator of transcription 3 either by directly targeting or via other pathway components upstream or downstream of signal transducer and activator of transcription 3 such as Janus kinases, members of the suppressor of cytokine signaling family, and other genes that regulate cell proliferation, apoptosis, migration, invasion, and epithelial-mesenchymal transition. However, signal transducer and activator of transcription 3 activation changes the pattern of expression of microRNAs and mediates tumorigenesis. Moreover, the relationship between signal transducer and activator of transcription 3 and microRNAs varies among different kinds of cancers. A specific microRNA may act as an oncogene or tumor suppressor in different cancers, and microRNAs also directly or indirectly regulate signal transducer and activator of transcription 3 via pathways in the same cancers. In this review, we focus on the reciprocal regulation and roles of microRNAs and signal transducer and activator of transcription 3 in cancer, as well as describe current research progress on this relationship. A better understanding of this relationship may facilitate in the identification of targets for clinical therapeutics.

STAT3 activation in infection and infection-associated cancer

The Janus kinase/signal transducers and activators for transcription (JAK/STAT) pathway plays crucial roles in regulating apoptosis, proliferation, differentiation, and the inflammatory response. The JAK/STAT families are composed of four JAK family members and seven STAT family members. STAT3 plays a key role in inducing and maintaining a pro-carcinogenic inflammatory microenvironment. Recent evidence suggests that STAT3 regulates diverse biological functions in pathogenesis of diseases, such as infection and cancer. In the current review, we will summarize the research progress of STAT3 activation in infection and cancers. We highlight our recent study on the novel role of STAT3 in Salmonella infection-associated colon cancer. Infection with bacterial AvrA-expressing Salmonella activates the STAT3 pathway, which induces the β-catenin signals and enhances colonic tumorigenesis. STAT3 may be a promising target in developing prevention and treatment for infectious diseases and infection-associated cancers.

MicroRNA-26a inhibits the growth and invasiveness of malignant melanoma and directly targets on MITF gene

Metastatic melanoma is the most aggressive form of skin cancer and is refractory to therapy. MicroRNAs have been recently discovered as novel molecules that provide therapeutic benefits against melanoma. This work aims to examine the effects of miR-26a and let-7a on the growth and invasiveness of malignant melanoma in vitro and in vivo. In addition, we elucidate the mechanism of action by identifying the target gene of miR-26a. Both miR-26a and let-7a inhibited proliferation and invasiveness and halted the cell cycle at the G₁/G₀ phase in SKMEL-28 and WM1552C malignant melanoma cell lines. Moreover, miR-26a potently induced apoptosis and downregulated the expressions of microphthalmia-associated transcription factor (MITF) and MAP4K3 in both cell lines. The luciferase reporter assay demonstrated that miR-26a suppresses MITF expression by binding the 3′-UTR, suggesting that MITF is a bona fide target of miR-26a. SiRNA knockdown of the MITF gene confirmed that miR-26a reduced cell viability and induced apoptosis by regulating MITF. Using a murine model, we also found miR-26a significantly retarded the growth of melanoma tumors in vivo. In conclusion, miR-26a and let-7a suppressed the growth and invasiveness of melanoma cells, suggesting that miR-26a and let-7a may represent novel therapies for malignant melanoma.

MicroRNAs in HPV associated cancers: small players with big consequences

INTRODUCTION

MicroRNAs (miRs) are short (~20 nucleotides) non-coding ribonuecleic acids (ncRNAs) known to be involved in cellular processes such as proliferation, differentiation, immune response, pathogenicity and tumourigenesis, among many others. The regulatory mechanisms exerted by miRs have been implicated in many cancers, including Human Papillomavirus (HPV)-associated cancers. Areas covered: In this review, the authors discuss the involvement of miRs (-143, -375, -21, -200, -296 etc.) that have been shown to be dysregulated in HPV-associated cancers. This review also encompasses both intracellular and exosomal miRs, and their potential as diagnostic biomarkers in saliva and blood. The authors have also attempted to dissect the functional impact of miRs on cellular processes such as changes in cellular polarity, loss of apoptosis and tumour suppression, and unchecked and uncontrolled cell cycle regulation, all of which ultimately lead to aberrant cellular proliferation. Expert commentary: Identification of dysregulated miRs in HPV-associated cancers opens up new opportunities to develop diagnostic, therapeutic and prognostic biomarkers. Studies on global expression patterns of miRs dysregulated in HPV-associated cancers can be instrumental in developing broader therapeutic strategies. Therapies like anti-miR, miR-replacement and those based on alternative natural products targeting miRs, need to be improved and better synchronized to be cost-effective and have better treatment outcomes.

Characterization of the microRNA profile in early-stage cervical squamous cell carcinoma by next-generation sequencing

Squamous cell carcinoma (SCC) is histologically the most prominent type of cervical cancer. There is accumulating evidence suggesting that microRNAs (miRNAs) play important regulatory roles in the biological processes of cervical squamous cell carcinoma (CSCC). Deciphering the miRNA regulatory network in CSCC could deepen our understanding at the molecular level of CSCC initiation and progression. In the present study, we performed next‑generation sequencing (NGS) to profile miRNA expression in 3 pairs of early-stage CSCC samples. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify primary findings in another 20 pairs of CSCC samples. We identified 37 known miRNAs that exhibited significant alterations in expression (2-fold change or greater), among which 8 miRNAs were upregulated and 29 miRNAs were downregulated. Nine of these miRNAs were selected for further qRT-PCR validation. A novel miRNA candidate was also reported for the first time in the present study to be upregulated. The Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that its target genes were involved in MAPK, calcium and adherent junction signaling pathways. The present study systematically characterized the miRNA expression variation in early-stage CSCC and provides novel biomarkers for diagnosis and treatment as well as an opportunity for further investigation of the molecular mechanisms underlying the pathogenesis and development of CSCC.

Long noncoding RNA MEG3 is downregulated in cervical cancer and affects cell proliferation and apoptosis by regulating miR-21

Recent research has found that long noncoding RNAs (lncRNAs) were involved in various human cancers. However, the role of these lncRNAs in cervical cancer remains unexplored. Therefore, we aimed to investigate the biological function of maternally expressed gene 3 (MEG3), a cancer-related lncRNA, and its underlying mechanism in cervical cancer. In this study, MEG3 expression of 108 patients' cervical cancer tissues and adjacent normal tissues was detected by quantitative real-time PCR analysis (qRT-PCR), and the functional effect of MEG3 was determined in vitro assays. We observed that MEG3 was downregulated in cervical cancer tissues, compared to the adjacent normal tissues, and was negatively related with FIGO stages, tumor size, lymphatic metastasis, HR-HPV infection and the expression of homo sapiens microRNA-21 (miR-21). Furthermore, we focused on the function and molecular mechanism of MEG3, finding that overexpression of MEG3 reduced the level of miR-21-5p expression, causing inhibition of proliferation and increased apoptosis in cervical cancer cells. In summary, our findings indicate that MEG3 function as a tumor suppressor by regulating miR-21-5p, resulting in the inhibition of tumor growth in cervical cancer. As a result, this study improves our understanding of the function of MEG3 in cervical cancer and will help to provide new potential target sites for cervical cancer treatment.

Micro ribonucleic acid-93 promotes oncogenesis of cervical cancer by targeting RAB11 family interacting protein 1

AIM

Micro ribonucleic acid (RNA)-93 (miR-93) is a novel oncogenic miRNA dysregulated in many types of tumors. We aimed to further study the expression pattern and clinical significance of miR-93 and its target, the RAB11 family interacting protein 1 (RAB11FIP1) gene, in cervical cancer.

METHODS

Mir-93 and RAB11FIP1 expression in cervical cancer (n = 168), cervical intraepithelial neoplasia (CIN) 2 or 3 (n = 60) and normal cervical tissues (n = 48) was examined by real-time reverse transcription polymerase chain reaction and immunohistochemical staining. Methyl thiazolyl tetrazolium assay, flow cytometry, and Transwell chamber invasion assay were performed to investigate the function of miR-93 in the proliferation, apoptosis and invasion of cervical cancer cell lines SiHa and CaSki. Luciferase activity assay was conducted to identify the target gene of miR-93.

RESULTS

Mir-93 expression levels in cervical cancer and CIN tissues were significantly increased (P = 0.032), but the RAB11FIP1 protein was significantly decreased (P = 0.006) compared with normal tissues. Neither was associated with clinicopathological variables. Enforced miR-93 knockdown or RAB11FIP1 overexpression suppressed proliferation and promoted apoptosis, but did not influence invasion in cervical cancer cells. Luciferase activity indicated that RAB11FIP1 was a direct target for miR-93.

CONCLUSIONS

Our findings suggest that overexpression of miR-93 via targeting RAB11FIP1 as an early event plays an important role in oncogenesis of cervical cancer. MiR-93 and its target protein RAB11FIP1 may be potential therapeutic targets for cervical cancer and its precursors.

MiR-21 modulates radiosensitivity of cervical cancer through inhibiting autophagy via the PTEN/Akt/HIF-1α feedback loop and the Akt-mTOR signaling pathway

MiR-21 is an important microRNA (miRNA) modulating radiosensitivity of cervical cancer cells. However, the underlying mechanism of miR-21 upregulation in radioresistant cervical cancer has not been fully understood. In addition, autophagy may either promote or alleviate radioresistance, depending on the types of cancer and tumor microenvironment. How autophagy affects radiosensitivity in cervical cancer and how miR-21 is involved in this process has not been reported. This study showed that miR-21 upregulation in radioresistant cervical cancer is related to HIF-1α overexpression. MiR-21 overexpression decreases PTEN, increases p-Akt, and subsequently increases HIF-1α expression, while miR-21 inhibition results in increased PTEN, decreased p-Akt, and then decreased HIF-1α. Therefore, we inferred that there is a HIF-1α-miR-21 positive feedback loop through the PTEN/Akt/HIF-1α pathway in cervical cancer cells. In addition, we also demonstrated that miR-21 confers decreased autophagy in cervical cancer cells after IR via the Akt-mTOR signaling pathway. Decreased autophagy is one of the potential mechanisms of increased radioresistance in cervical cancer cells. These findings expand our understanding of radioresistance development in cervical cancer.

Stat3 regulates ErbB-2 expression and co-opts ErbB-2 nuclear function to induce miR-21 expression, PDCD4 downregulation and breast cancer metastasis

Membrane overexpression of the receptor tyrosine kinase ErbB-2 (MErbB-2) accounts for a clinically aggressive breast cancer (BC) subtype (ErbB-2-positive) with increased incidence of metastases. We and others demonstrated that nuclear ErbB-2 (NErbB-2) also plays a key role in BC and is a poor prognostic factor in ErbB-2-positive tumors. The signal transducer and activator of transcription 3 (Stat3), another player in BC, has been recognized as a downstream mediator of MErbB-2 action in BC metastasis. Here, we revealed an unanticipated novel direction of the ErbB-2 and Stat3 interaction underlying BC metastasis. We found that Stat3 binds to its response elements (GAS) at the ErbB-2 promoter to upregulate ErbB-2 transcription in metastatic, ErbB-2-positive BC. We validated these results in several BC subtypes displaying metastatic and non-metastatic ability, highlighting Stat3 general role as upstream regulator of ErbB-2 expression in BC. Moreover, we showed that Stat3 co-opts NErbB-2 function by recruiting ErbB-2 as its coactivator at the GAS sites in the promoter of microRNA-21 (miR-21), a metastasis-promoting microRNA (miRNA). Using an ErbB-2 nuclear localization domain mutant and a constitutively activated ErbB-2 variant, we found that NErbB-2 role as a Stat3 coactivator and also its direct role as transcription factor upregulate miR-21 in BC. This reveals a novel function of NErbB-2 as a regulator of miRNAs expression. Increased levels of miR-21, in turn, downregulate the expression of the metastasis-suppressor protein programmed cell death 4 (PDCD4), a validated miR-21 target. Using an in vivo model of metastatic ErbB-2-postive BC, in which we silenced Stat3 and reconstituted ErbB-2 or miR-21 expression, we showed that both are downstream mediators of Stat3-driven metastasis. Supporting the clinical relevance of our results, we found an inverse correlation between ErbB-2/Stat3 nuclear co-expression and PDCD4 expression in ErbB-2-positive primary invasive BCs. Our findings identify Stat3 and NErbB-2 as novel therapeutic targets to inhibit ErbB-2-positive BC metastasis.

Relevance of miR-21 in regulation of tumor suppressor gene PTEN in human cervical cancer cells

BACKGROUND

Expression of the microRNA miR-21 has been found to be altered in almost all types of cancers and it has been classified as an oncogenic microRNA or oncomir. Due to the critical functions of its target proteins in various signaling pathways, miR-21 is an attractive target for genetic and pharmacological modulation in various cancers. Cervical cancer is the second most common cause of death from cancer in women worldwide and persistent HPV infection is the main etiologic agent. This malignancy merits special attention for the development of new treatment strategies. In the present study we analyze the role of miR-21 in cervical cancer cells.

METHODS

To identify the downstream cellular target genes of upstream miR-21, we silenced endogenous miR-21 expression in a cervical intraepithelial neoplasia-derived cell lines using siRNAs. The effect of miR-21 on gene expression was assessed in cervical cancer cells transfected with the siRNA expression plasmid pSIMIR21. We identified the tumor suppressor gene PTEN as a target of miR-21 and determined the mechanism of its regulation throughout reporter construct plasmids. Using this model, we analyzed the expression of miR-21 and PTEN as well as functional effects such as autophagy and apoptosis induction.

RESULTS

In SiHa cells, there was an inverse correlation between miR-21 expression and PTEN mRNA level as well as PTEN protein expression in cervical cancer cells. Transfection with the pSIMIR21 plasmid increased luciferase reporter activity in construct plasmids containing the PTEN-3'-UTR microRNA response elements MRE21-1 and MRE21-2. The role of miR-21 in cell proliferation was also analyzed in SiHa and HeLa cells transfected with the pSIMIR21 plasmid, and tumor cells exhibited markedly reduced cell proliferation along with autophagy and apoptosis induction.

CONCLUSIONS

We conclude that miR-21 post-transcriptionally down-regulates the expression of PTEN to promote cell proliferation and cervical cancer cell survival. Therefore, it may be a potential therapeutic target in gene therapy for cervical cancer.

The effects of lanthanum chloride on proliferation and apoptosis of cervical cancer cells: involvement of let-7a and miR-34a microRNAs

Lanthanide elements have been documented to possess various biologic effects, and their compounds have been studied intensely for their anti-cancer potential. However, the underlying mechanisms remain largely unknown. In the present study, we propose that the levels of proliferation and apoptosis related microRNAs (miRNAs), let-7a and miR-34a, which mediate the apoptosis of cervical cancer cells, can be affected by the lanthanum ion. Our data showed that LaCl3 inhibited the proliferation and induced the apoptosis of cervical cancer cells both in vivo and in vitro by regulating let-7a, miR-34a and their downstream genes. This study provides novel evidence demonstrating that the anticancer mechanism of lanthanum chloride is partially attributed to miRNAs regulation and establishes an experimental basis for the clinical application of lanthanum chloride as an anti-cancer drug.

MiRNA-based therapeutic intervention of cancer

MicroRNAs (miRNAs) are important modulators of eukaryotic gene expression. By targeting protein coding transcripts, miRNAs influence the cellular transcriptome and proteome, thus helping to determine cell fate. MiRNAs have emerged as crucial molecules in cancer research, in which recent studies have linked erratic expression of miRNAs to carcinogenesis and have provided solid evidence for their potential in cancer therapy. This review briefly summarises the recent knowledge on the involvement of miRNAs in tumourigenesis and reviews current studies on the therapeutic strategies and advances in the delivery of miRNAs.

Alterations in microRNAs miR-21 and let-7a correlate with aberrant STAT3 signaling and downstream effects during cervical carcinogenesis

Background

Present study provides clinical evidence of existence of a functional loop involving miR-21 and let-7a as potential regulators of aberrant STAT3 signaling recently reported by our group in an experimental setup (Shishodia et al. BMC Cancer 2014, 14:996). The study is now extended to a set of cervical tissues that represent natural history of human papillomavirus (HPV)-induced tumorigenic transformation.

Materials and methods

Cervical tissues from histopathologically-confirmed pre-cancer (23) and cancer lesions (56) along with the normal control tissues (23) were examined for their HPV infection status, expression level of miR-21 & let-7a and STAT3 & pSTAT3 (Y705) by PCR-based genotyping, quantitative real-time PCR and immunoblotting.

Results

Analysis of cancer tissues revealed an elevated miR-21 and reduced let-7a expression that correspond to the level of STAT3 signaling. While miR-21 showed direct association, let-7a expression was inversely related to STAT3 expression and its activation. In contrast, a similar reciprocal expression kinetics was absent in LSIL and HSIL tissues which overexpressed let-7a. miR-21 was found differentially overexpressed in HPV16-positive lesions with a higher oncoprotein E6 level. Overexpression of miR-21 was accompanied by elevated level of other STAT3-regulated gene products MMP-2 and MMP-9. Enhanced miR-21 was found associated with decreased level of STAT3 negative regulator PTEN and negative regulator of MMPs, TIMP-3.

Conclusion

Overall, our study suggests that the microRNAs, miR-21 and let-7a function as clinically relevant integral components of STAT3 signaling and are responsible for maintaining activated state of STAT3 in HPV-infected cells during cervical carcinogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0385-2) contains supplementary material, which is available to authorized users.

Impact of Nutrition on Non-Coding RNA Epigenetics in Breast and Gynecological Cancer

Cancer is the second leading cause of death in females. According to the American Cancer Society, there are 327,660 new cases in breast and gynecological cancers estimated in 2014, placing emphasis on the need for cancer prevention and new cancer treatment strategies. One important approach to cancer prevention involves phytochemicals, biologically active compounds derived from plants. A variety of studies on the impact of dietary compounds found in cruciferous vegetables, green tea, and spices like curry and black pepper have revealed epigenetic changes in female cancers. Thus, an important emerging topic comprises epigenetic changes due to the modulation of non-coding RNA levels. Since it has been shown that non-coding RNAs such as microRNAs and long non-coding RNAs are aberrantly expressed in cancer, and furthermore are linked to distinct cancer phenotypes, understanding the effects of dietary compounds and supplements on the epigenetic modulator non-coding RNA is of great interest. This article reviews the current findings on nutrition-induced changes in breast and gynecological cancers at the non-coding RNA level.

Model systems to study the life cycle of human papillomaviruses and HPV-associated cancers

The prevalent human papillomaviruses (HPVs) infect either cutaneous or mucosal epithelium. Active Infections lead to epithelial hyperprolifeation and are usually cleared in healthy individuals within a year. Persistent infections in the anogenital tracts by certain high-risk genotypes such as HPV-16, HPV-18 and closely related types, can progress to high grade dysplasias and carcinomas in women and men, including cervical, vulva, penile and anal cancers. A significant fraction of the head and neck cancers are also caused by HPV-16. The viral oncogenes responsible for neoplastic conversion are E6 and E7 that disrupt the pathways controlled by the two major tumor suppressor genes, p53 and members of pRB family. Because HPV cannot be propagated in conventional submerged monolayer cell cultures, organotypic epithelial raft cultures that generate a stratified and differentiated epithelium have been used to study the viral life cycle. This article describes several systems to examine aspects of the viral productive phase, along with the advantages and limitations. Animal model systems of HPV carcinogenesis are also briefly described.

miR-21 modulates resistance of HR-HPV positive cervical cancer cells to radiation through targeting LATS1

Although multiple miRNAs are found involved in radioresistance development in HR-HPV positive (+) cervical cancer, only limited studies explored the regulative mechanism of the miRNAs. miR-21 is one of the miRNAs significantly upregulated in HR-HPV (+) cervical cancer is also significantly associated with radioresistance. However, the detailed regulative network of miR-21 in radioresistance is still not clear. In this study, we confirmed that miR-21 overexpression was associated with higher level of radioresistance in HR-HPV (+) cervical cancer patients and thus decided to further explore its role. Findings of this study found miR-21 can negatively affect radiosensitivity of HR-HPV (+) cervical cancer cells and decrease radiation induced G2/M block and increase S phase accumulation. By using dual luciferase assay, we verified a binding site between miR-21 and 3'-UTR of large tumor suppressor kinase 1 (LATS1). Through direct binding, miR-21 can regulate LATS1 expression in cervical cancer cells. LATS1 overexpression can reverse miR-21 induced higher colony formation rate and also reduced miR-21 induced S phase accumulation and G2/M phase block reduction under radiation treatment. These results suggested that miR-21-LATS1 axis plays an important role in regulating radiosensitivity.

Inhibitory effect and mechanisms of microRNA-146b-5p on the proliferation and metastatic potential of Caski human cervical cancer cells

Cervical cancer is a common cause of cancer‑associate mortality in females, and metastasis is strongly associated with failure of cervical cancer treatment. Previous studies have indicated that microRNA (miR)‑146b‑5p is involved in the inhibition of proliferation and metastasis of numerous human cancer types. The aim of the present study was to explore the inhibitory effect of miR‑156b‑5p on the proliferation and metastatic potential of Caski human cervical cancer cells, as well as to determine the mechanisms by which it proceeds. The results demonstrated that miR‑146b‑5p was able to inhibit the proliferative, invasive and adhesive potential and block the cell cycle progression of Caski human cervical cancer cells, as determined using MTS and transwell assays as well as flow cytometry. Furthermore, quantitative polymerase chain reaction and western blot analysis revealed that transfection with miR‑146b‑5p decreased the mRNA and protein expression levels of C‑X‑C chemokine receptor type 4, matrix metalloproteinase‑2 and ‑9, c‑Myc, cyclin D1 and human papilloma virus 16. In addition, the secretion levels of transforming growth factor‑β, monocyte chemoattractant protein‑1 and tumor necrosis factor‑α, the telomerase activity, the phosphorylation of c‑Jun N‑terminal protein kinase and protein kinase B and the transcriptional activities of nuclear factor‑κB, signal transducer and activator of transcription‑3 and ‑5 were reduced. However, increased levels of p27 and p53 were detected in the miR‑146b‑5p‑overexpressing Caski cells. These results indicate that miR‑146b‑5p may be a potential therapeutic strategy for the treatment of cervical cancer through regulation of cell chemotaxis and the cell cycle.