MiR-21 is involved in cervical squamous cell tumorigenesis and regulates CCL20

MicroRNA-21 modulates radiation resistance through upregulation of hypoxia-inducible factor-1α-promoted glycolysis in non-small cell lung cancer cells

Aberrant microRNA (miRNA) expression in cancer affects the transcription of target genes, and profoundly influences cancer‑associated signaling pathways. Radiation resistance is a major problem encountered in the treatment of cancer. The present study aimed to investigate the role of miRNA (miR)‑21 in the development of radiation resistance in non‑small cell lung cancer cells. A radiation‑resistant cell line was generated from A549 cells. Significant upregulation of miR‑21 was detected in the radioresistant cancer cells, as compared with the radiosensitive cells, and overexpression of miR‑21 rendered A549 parental cells resistant to radiation. In addition, glycolysis was increased in the radioresistant cells, as compared with the sensitive cells. Furthermore, hypoxia‑inducible factor‑1α (HIF1α) was upregulated by miR‑21 in radioresistant cells, resulting in promotion of the key enzymes of glycolysis. Inhibition of HIF1α by small interfering RNA suppressed glycolysis and resensitized the cancer cells to radiation, whereas the recovery of HIF1α in miR‑21‑inhibited radioresistant cells resulted in recovery of radioresistance. In conclusion, the present study suggested that miR‑21 may modulate radioresistance through the upregulation of HIF1α. These results may provide a novel perspective on miRNA for the development of anti-radioresistance drugs.

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.

MicroRNAs Expressed during Viral Infection: Biomarker Potential and Therapeutic Considerations

MicroRNAs (miRNAs) are short sequences of noncoding single-stranded RNAs that exhibit inhibitory effects on complementary target mRNAs. Recently, it has been discovered that certain viruses express their own miRNAs, while other viruses activate the transcription of cellular miRNAs for their own benefit. This review summarizes the viral and/or cellular miRNAs that are transcribed during infection, with a focus on the biomarker and therapeutic potential of miRNAs (or their antagomirs). Several human viruses of clinical importance are discussed, namely, herpesviruses, polyomaviruses, hepatitis B virus, hepatitis C virus, human papillomavirus, and human immunodeficiency virus.

MicroRNAs are involved in cervical cancer development, progression, clinical outcome and improvement treatment response (Review)

Cervical cancer (CC) is the third most diagnosed cancer among females worldwide and the fourth cause of cancer-related mortality. Prophylactic HPV vaccines and traditional pap-smear screening are undoubtedly capable of decreasing the incidence and mortality of CC. However, a large number of females succumb to the disease each year due to late diagnosis and resistance to conventional treatments. Thus, it is necessary to identify new molecular markers to predict the clinical outcome and to design powerful treatments. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and are involved in the modulation of several cell pathways associated with progression from pre-malignant to invasive and metastatic disease, increasing tumor malignancy. The aim of this review was to summarize the recent data that describe the important role of miRNAS involved in CC in order to determine their potential as prognostic biomarkers and as therapy targets. Studies of >40 miRNAs with roles in cancer regulation were identified. We also identified 17 miRNAs associated with progression, 12 involved with clinical outcome and 7 that improved CC treatment response. The present review is expected to broaden understanding of the functional role and potential clinical uses of miRNAs in CC.

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.

miR-212/132 downregulates SMAD2 expression to suppress the G1/S phase transition of the cell cycle and the epithelial to mesenchymal transition in cervical cancer cells

MicroRNAs (miRNAs), a class of small noncoding RNAs that regulate target gene expression, play an important role in cancer initiation, progression, and metastasis. However, the role of many miRNAs in cervical cancer is not fully understood. In this study, we found that miR-212 and miR-132 from the same gene cluster are downregulated in human cervical cancer tissues when compared with adjacent noncancerous tissues. The overexpression of miR-212/132 not only led to a delay in the G1/S phase transition and repressed cell proliferation but also resulted in an increase in E-cadherin expression and a decrease in vimentin, suppressing the epithelial to mesenchymal transition and migration and invasion in cervical cancer cells. Subsequently, SMAD2 was identified as a common target of miR-212/132 and was found to be negatively regulated by miR-212/132 at the mRNA and protein levels. Furthermore, SMAD2 silencing led to the same effect on cervical cancer cells as miR-212/132 overexpression. Importantly, SMAD2 overexpression partially reversed the cellular phenotypes induced by miR-212/132 overexpression. In conclusion, our study indicated that miR-212/132 functions as tumor suppressor by targeting SMAD2 in cervical cancer.

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.

Role of microRNAs in cancers of the female reproductive tract: insights from recent clinical and experimental discovery studies

microRNAs (miRNAs) are small RNA molecules that represent the top of the pyramid of many tumorigenesis cascade pathways as they have the ability to affect multiple, intricate, and still undiscovered downstream targets. Understanding how miRNA molecules serve as master regulators in these important networks involved in cancer initiation and progression open up significant innovative areas for therapy and diagnosis that have been sadly lacking for deadly female reproductive tract cancers. This review will highlight the recent advances in the field of miRNAs in epithelial ovarian cancer, endometrioid endometrial cancer and squamous-cell cervical carcinoma focusing on studies associated with actual clinical information in humans. Importantly, recent miRNA profiling studies have included well-characterized clinical specimens of female reproductive tract cancers, allowing for studies correlating miRNA expression with clinical outcomes. This review will summarize the current thoughts on the role of miRNA processing in unique miRNA species present in these cancers. In addition, this review will focus on current data regarding miRNA molecules as unique biomarkers associated with clinically significant outcomes such as overall survival and chemotherapy resistance. We will also discuss why specific miRNA molecules are not recapitulated across multiple studies of the same cancer type. Although the mechanistic contributions of miRNA molecules to these clinical phenomena have been confirmed using in vitro and pre-clinical mouse model systems, these studies are truly only the beginning of our understanding of the roles miRNAs play in cancers of the female reproductive tract. This review will also highlight useful areas for future research regarding miRNAs as therapeutic targets in cancers of the female reproductive tract.

Quantifying mRNA and microRNA with qPCR in cervical carcinogenesis: a validation of reference genes to ensure accurate data

A number of recent studies have catalogued global gene expression patterns in a panel of normal, tumoral cervical tissues so that potential biomarkers can be identified. The qPCR has been one of the most widely used technologies for detecting these potential biomarkers. However, few studies have investigated a correct strategy for the normalization of data in qPCR assays for cervical tissues. The aim of this study was to validate reference genes in cervical tissues to ensure accurate quantification of mRNA and miRNA levels in cervical carcinogenesis. For this purpose, some issues for obtaining reliable qPCR data were evaluated such as the following: geNorm analysis with a set of samples which meet all of the cervical tissue conditions (Normal + CIN1 + CIN2 + CIN3 + Cancer); the use of individual Ct values versus pooled Ct values; and the use of a single (or multiple) reference genes to quantify mRNA and miRNA expression levels. Two different data sets were put on the geNorm to assess the expression stability of the candidate reference genes: the first dataset comprised the quantities of the individual Ct values; and the second dataset comprised the quantities of the pooled Ct values. Moreover, in this study, all the candidate reference genes were analyzed as a single “normalizer”. The normalization strategies were assessed by measuring p16^INK4a and miR-203 transcripts in qPCR assays. We found that the use of pooled Ct values, can lead to a misinterpretation of the results, which suggests that the maintenance of inter-individual variability is a key factor in ensuring the reliability of the qPCR data. In addition, it should be stressed that a proper validation of the suitability of the reference genes is required for each experimental setting, since the indiscriminate use of a reference gene can also lead to discrepant results.

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.

MicroRNA target prediction: theory and practice

The present study is one of the few that includes tissue samples in the evaluation of target prediction algorithms designed to detect microRNA (miRNA) sequences that might interact with particular messenger RNA (mRNA) sequences. Twelve different target prediction tools were used to find miRNA sequences that might interact with CCL20 gene expression. Different algorithms predicted controversial miRNA sequences for CCL20 regulation due to a different weighting of parameters. Hsa-miR-21 and hsa-miR-145 suggested by four or more programs were chosen for further investigation. Possible real interaction of these miRNA sequences with CCL20 gene expression was monitored using luciferase assays and expression analyses of tissue samples of colorectal adenocarcinoma by either qRT-PCR or ELISA. Folding status of seed-binding sites in complete mRNA and 3'UTR of CCL20 was predicted. Prediction of miRNA expression was attempted based on CCL20 expression data. Eight of the target prediction tools forecasted a role for hsa-miR-21 and four mentioned hsa-miR-145 in CCL20 gene regulation. Laboratory experimentation showed that CCL20 may serve as a target of hsa-miR-21 but not hsa-miR-145. Expression of the molecules resulted in no clear assertion. Folding of seed-binding sites was predicted to be relatively constant for the complete mRNA and 3'UTR. Predicting miRNA expression based on target gene expression was impossible. This might be attributable to the fact that effects of miRNA activity may oscillate between gene product repression and activation. Additional systematic studies are needed to address this issue.

Microarray analysis revealed markedly differential miRNA expression profiles in cervical intraepithelial neoplasias and invasive squamous cell carcinoma

AIMS

To investigate the alterations in miRNA expression during the progression of dysplasia in cervical epithelium.

METHODS

A global miRNA expression profile of normal cervical squamous epithelium (Normal), cervical intraepithelial neoplasia (CIN) 3 and invasive squamous cell carcinoma (ISCC) was produced using the seventh generation of the miRCURY™ LNA microRNA Array (Exiqon, Vedbaek, Denmark). The reliability of miRNA arrays was verified by reverse transcription PCR.

RESULTS

Normal, CIN 3 and ISCC showed distinct miRNA expression profiles. The differentially expressed miRNAs in ISCC versus CIN 3 clearly differed from that in CIN 3 versus Normal. Compared with ISCC versus Normal, more identical miRNAs were found in ISCC versus CIN 3 than in CIN 3 versus Normal.

CONCLUSION

A particular set of miRNAs was associated with the progression of normal cervical epithelium to CIN 3 and CIN 3 to ISCC. The miRNA profile changed more noticeably in the progression of CIN to ISCC than normal cervical epithelium to CIN.

MicroRNA in cervical cancer: OncomiRs and tumor suppressor miRs in diagnosis and treatment

Cervical cancer is a female-specific disease with a high incidence and mortality. MicroRNAs (miRNAs) are implicated in posttranscriptional regulation of gene expression and in the pathogenic mechanisms of cancer, suggesting their importance in diagnosis and treatment. miRNAs may have roles in the pathogenesis of cervical cancer based on the increases or decreases in several specific miRNAs found in patients with this disease. The miRNAs implicated in cervical cancer are miR-21, miR-126, and miR-143, and clinical application of these miRNAs for diagnosis and treatment is under investigation. Methods for diagnosis of cervical cancer include analysis of changes in the levels of specific miRNAs in serum and determination of aberrant hypermethylation of miRNAs. Supplementation of miR-143 or inhibition of miR-21 activity in vivo may be therapeutic strategy for cervical cancer. Previous approaches to development of siRNA as a drug have provided information for establishment of therapy based on these approaches, and an anti-miR-21 inhibitor has been developed. miRNAs also have effects on drug resistance and may be useful in combination therapy with other drugs.

Molecular targets of HPV oncoproteins: potential biomarkers for cervical carcinogenesis

Cervical cancer is the second most common cancer among women worldwide and is responsible for 275,000 deaths each year. Persistent infection with high-risk human papillomavirus (HR-HPV) is an essential factor for the development of cervical cancer. Although the process is not fully understood, molecular mechanisms caused by HPV infection are necessary for its development and reveal a large number of potential biomarkers for diagnosis and prognosis. These molecules are host genes and/or proteins, and cellular microRNAs involved in cell cycle regulation that result from disturbed expression of HR-HPV E5, E6 and E7 oncoproteins. One of the current challenges in medicine is to discover potent biomarkers that can correctly diagnose cervical premalignant lesions and standardize clinical management. Currently, studies are showing that some of these molecules are potential biomarkers of cervical carcinogenesis, and it is possible to carry out a more accurate diagnosis and provide more appropriate follow-up treatment for women with cervical dysplasia. In this paper, we review recent research studies on cell cycle molecules deregulated by HPV infections, as well as their potential use for cervical cancer screening.

Deregulation of the miRNAs expression in cervical cancer: human papillomavirus implications

MicroRNAs (miRNAs) are a class of small non coding RNAs of 18-25 nucleotides in length. The temporal or short-lived expression of the miRNAs modulates gene expression post transcriptionally. Studies have revealed that miRNAs deregulation correlates and is involved with the initiation and progression of human tumors. Cervical cancer (CC) displays notably increased or decreased expression of a large number of cellular oncogenic or tumor suppressive miRNAs, respectively. However, understanding the potential role of miRNAs in CC is still limited. In CC, the high-risk human papillomaviruses (HR-HPVs) infection can affect the miRNAs expression through oncoprotein E6 and E7 that contribute to viral pathogenesis, although other viral proteins might also be involved. This deregulation in the miRNAs expression has an important role in the hallmarks of CC. Interestingly, the miRNA expression profile in CC can discriminate between normal and tumor tissue and the extraordinary stability of miRNAs makes it suitable to serve as diagnostic and prognostic biomarkers of cancer. In this review, we will summarize the role of the HR-HPVs in miRNA expression, the role of miRNAs in the hallmarks of CC, and the use of miRNAs as potential prognostic biomarkers in CC.

Exploration of tumor-suppressive microRNAs silenced by DNA hypermethylation in cervical cancer

Background

Multiple studies proved that miRNAs have a causal role in tumorigenesis. Some miRNAs are regulated by epigenetic alterations in their promoter regions and can be activated by chromatin- modifying drugs.

Methods

We treated cervical cancer cells with 5-aza-2’-deoxycytidine and get a microarray analysis. Dysregulation of miRNAs was measured by qPCR in cervical cell lines and methylation status of them in cervical cancer tissue were performed with MeDIP-qPCR assay.

Results

We found hypermethylation of miR-432, miR-1286, miR-641, miR-1290, miR-1287 and miR-95 may have some relationship with HPV infection in cervical cell lines. In primary tumors of cervix with paired normal tissue, expression levels of miRNAs were inversely correlated with their DNA methylation status in the cervical cancer cell lines treated with 5-AZA.

Conclusions

Our results indicate that miRNAs might play a role in the pathogenesis of human cervical cancer with HPV and identify altered miRNA methylation as a possible epigenetic mechanism involved in their aberrant expression.

Aberrant expression of long noncoding RNAs in cervical intraepithelial neoplasia

OBJECTIVE

Long noncoding RNAs (lncRNAs) are a unique class of messenger RNA-like transcripts of at least 200 nucleotides in length with no significant protein-coding capacity. Aberrant lncRNA expression is emerging as a major component of the cancer transcriptome. Here, we sought to determine if differential lncRNA expression is a feature of the human cervical intraepithelial neoplasia (CIN) transcriptome.

METHODS

Sequence data were derived from 16 long serial analyses of gene expression (L-SAGE) libraries constructed from cervical specimens representing mild (CIN1), moderate (CIN2), and severe (CIN3) histopathologic grades of CIN. A novel lncRNA discovery pipeline was developed to query the expression of lncRNAs within the SAGE data sets.

RESULTS

A total of 2,230,370 sequence tags were delineated from the 16 SAGE libraries, representing the expression of 367,482 unique tags at varying abundance. Using a novel stepwise filtering strategy, we analyzed the cervical SAGE libraries and identified the expression profiles of 1056 lncRNAs in the human cervix. We present the first lncRNA expression profile derived from nonneoplastic cervical tissue and establish that changes in lncRNA expression do occur in cervical intraepithelial lesions. Our analysis also shows statistically significant aberrant expression of lncRNAs in the 3 CIN grades, suggesting that these unique noncoding RNA transcripts may contribute to the development and progression of precursor lesions.

CONCLUSIONS

Through the analysis of L-SAGE libraries constructed from cervical specimens, we provide the first lncRNA expression profile of the cervix and demonstrate aberrant expression in early-stage neoplasia.

The microRNA-302-367 cluster suppresses the proliferation of cervical carcinoma cells through the novel target AKT1

The miR-302-367 cluster is specifically expressed in human embryonic stem cells and has been shown to convert human somatic cells into induced pluripotent stem cells. Here, we investigated the role of the miR-302-367 cluster in cervical carcinoma. The cluster was not endogenously expressed in cervical cancer cells, and its ectopic expression did not reprogram the cervical cancer cells to an embryonic stem cell-like state. However, ectopic expression of the miR-302-367 cluster in HeLa and SiHa cervical cancer cells inhibited cell proliferation and tumor formation by blocking the G1/S cell cycle transition. We identified a new cell cycle regulatory pathway in which the miR-302-367 cluster directly down-regulated both cyclin D1 and AKT1 and indirectly up-regulated p27(Kip1) and p21(Cip1), leading to the suppression of cervical cancer cell proliferation. Our findings suggest that the miR-302-367 cluster may be used as a therapeutic reagent for the treatment of cervical carcinoma.

The oncogenic microRNA OncomiR-21 overexpressed during Marek's disease lymphomagenesis is transactivated by the viral oncoprotein Meq

Gallid herpesvirus 2 (GaHV-2) is an oncogenic herpesvirus that causes T lymphoma in chicken. GaHV-2 encodes a basic leucine zipper (bZIP) protein of the AP-1 family, Meq. Upon formation of homo- or heterodimers with c-Jun, Meq may modulate the expression of viral and cellular genes involved in lymphomagenesis. GaHV-2 also encodes viral microRNAs (miRNAs) involved in latency and apoptosis escape. However, little is known about cellular miRNA deregulation during the development of GaHV-2-associated lymphoma. We determined the cellular miRNA expression profiles of chickens infected with a very virulent strain (RB-1B) or a vaccine strain (CVI988) or noninfected. Among the most deregulated cellular miRNAs, we focused our efforts on gga-miR-21, which is upregulated during GaHV-2 infection. We mapped the gga-miR-21 promoter to the 10th intron of the TMEM49 gene and found it to be driven by AP-1- and Ets-responsive elements. We show here that the viral oncoprotein Meq binds to this promoter, thereby transactivating gga-miR-21 expression. We confirmed that this miRNA targets chicken programmed death cell 4 (PDCD4) and promotes tumor cell growth and apoptosis escape. Finally, gga-miR-21 was overexpressed only during infection with a very virulent strain (RB-1B) and not during infection with a nononcogenic strain (CVI988), providing further evidence for its role in GaHV-2 lymphomagenesis. Our data therefore suggest an additional role for Meq in GaHV-2-mediated lymphomagenesis through the induction of miR-21 expression.

miR-511 and miR-1297 inhibit human lung adenocarcinoma cell proliferation by targeting oncogene TRIB2

microRNAs (miRNAs) are small noncoding RNAs that regulate genes and contribute to many kinds of human diseases, including cancer. Two miRNAs, miR-511 and miR-1297, were investigated for a possible role in adenocarcinoma based on predicted binding sites for the TRIB2 oncogene by microRNA analysis software, and the pcDNA-GFP-TRIB2-3'UTR vector was constructed to investigate the interaction between TRIB2 and miR-511/1297 in the adenocarcinoma cell line A549. Green fluorescent protein (GFP) expression was estimated by fluorescence microscopy and flow cytometry after A549 cells were co-transfected with miR-511 (or miR-1297) and pcDNA-GFP-TRIB2-3'UTR vector. The expression of GFP in the miR-511- and miR-1297-treated cells was significantly downregulated in contrast with the negative-control (NC) miRNA-treated cells. The decreased expression of TRIB2 was further detected after miR-511 (or miR-1297) treatment by western blotting. The MTT test showed inhibition of A549 cell proliferation and Annexin V-FITC/PI dual staining showed increased apoptosis in the miR-511- and miR-1297-treated cells compared to the NC cultures. A transcription factor downstream of TRIB2, the CCAAT/enhancer-binding protein alpha (C/EBPα), was expression at higher levels after miR-511 (or miR-1297) decreasing TRIB2 expression. Our results illustrate that miR-511 and miR-1297 act as tumor suppressor genes, which could suppress A549 cell proliferation in vitro and in vivo by suppressing TRIB2 and further increasing C/EBPα expression.

Integrative analysis in oral squamous cell carcinoma reveals DNA copy number-associated miRNAs dysregulating target genes

OBJECTIVE

To better understand possible mechanisms involved in the dysregulation of gene expression unique to oral squamous cell carcinoma (OSCC) metastasis, the investigators examined the differential expression of microRNAs (miRNAs) in OSCC metastasis and their functional impact on target gene expression.

STUDY DESIGN

Observational assessment of DNA copy number, miRNA, and RNA expression in primary and metastatic OSCC.

SETTING

University of Washington Medical Center and affiliated hospitals.

SUBJECTS

Tumor samples were taken from patients with primary incident OSCC; cells were laser-capture microdissected from 17 nonmetastatic primary tumors and 20 metastatic lymph nodes.

METHODS

DNA copy number aberrations and gene expression profiles were previously determined using Affymetrix 250K Nsp I SNP arrays and HU133 plus 2.0 expression arrays. miRNAs were interrogated with Exiqon's Ready-to-Use PCR Panels assessing the expression of 368 human miRNAs.

RESULTS

Investigators found 31 miRNAs differentially expressed between metastatic and nonmetastatic samples (false discovery rate <0.4; 26 overexpressed and 5 underexpressed in metastatic samples). Expression of 7 of these miRNAs was significantly associated with their DNA copy numbers, and expressions of 8 of these miRNAs were significantly associated with their target genes. Among these unique miRNAs, miR-140-3p, miR-29c, and miR-29a were differentially expressed in metastasis versus nonmetastatic samples and had a strong positive correlation with their DNA copy numbers and a negative correlation with the expression of their target genes.

CONCLUSION

Results suggest that DNA copy number aberration may play a role in the dysregulation of some differentially expressed miRNAs in OSCC metastasis, warranting further investigation.

Overexpression of CCL20 and its receptor CCR6 predicts poor clinical prognosis in human gliomas

Recent studies have demonstrated that the chemokine CCL20 and its receptor CCR6 may be involved in tumorigenesis, tumor progression and metastatic spread of various human malignancies. The aim of this study was to investigate the clinicopathological significance and prognostic value of CCL20 and CCR6 expression in human malignant glioma. CCL20 and CCR6 expression in human gliomas and nonneoplastic brain tissues was measured by immunohistochemistry. The association of CCL20 and CCR6 expression with clinicopathological factors or prognosis in glioma patients was statistically analyzed. The expression levels of CCL20 and CCR6 proteins were both up-regulated in glioma tissues. There was a significantly positive correlation between the expression of the two markers (r = 0.88; P < 0.001). In addition, the overexpressions of CCL20 and CCR6 were both detected in high-grade glioma tissues compared with those in low-grade tissues and increased with ascending tumor World Health Organization (WHO) grades (P = 0.006 and 0.008, respectively). The increased expressions of CCL20 and CCR6 proteins were also significantly correlated with low Karnofsky performance score (both P = 0.01). Moreover, univariate analysis found that CCL20 expression (P = 0.002), CCR6 expression (P = 0.002) and CCL20/CCR6 co-expression (P < 0.001) were all significantly associated with poor prognosis. In particular, glioma patients with CCL20/CCR6 co-expression have the shortest overall survival. Multivariate analysis further identified the expression levels of CCL20 and CCR6 to be independent prognostic factors. Our data suggest for the first time that CCL20 and CCR6 might play an important role in the regulation of aggressiveness in human gliomas. The up-regulation of CCL20 and CCR6 might be closely associated with poor clinical outcome of patients with gliomas.