MicroRNAs: exploring a new dimension in the pathogenesis of kidney cancer

A Comprehensive Review on the Importance of MiRNA-206 in the Animal Model and Human Diseases

MicroRNA-206 (miR-206) is a microRNA that is involved in many human diseases, such as myasthenia gravis, osteoarthritis, depression, cancers, etc. Both inhibition effects and progression roles of miR-206 have been reported for the past few years. High expression of miR-206 was observed in patients with osteoarthritis, gastric cancer and epithelial ovarian cancer compared to normal people. The study also showed that miR-206 promotes cancer progression in breast cancer patients and avascular necrosis of the femoral head. Meanwhile, several studies have shown that expression levels of miR-206 were down-regulated in laryngeal carcinoma cell multiplication, as well as in hepatocellular carcinoma, non-small lung cancer and infantile hemangioma. Moreover, miR-206 was up-regulated in the mild stage of amyotrophic lateral sclerosis patients and then down-regulated in the moderate and severe stages, indicating that miR-206 has the double effects of starting and aggravating the disease. In neuropsychiatric disorders, such as depression, miR-206 also plays an important role in the progression of the disease; the level of miR-206 is most highly expressed in the brains of patients with depression. In the current review, we summarize the role of miR-206 in various diseases, and miR-206 may be developed as a new biomarker for diagnosing diseases in the near future.

Inflammation- and cancer-related microRNAs in rat renal cortex after subchronic exposure to fluoride

The proximal tubule is a target of subchronic exposure to fluoride (F) in the kidney. Early markers are used to classify kidney damage, stage, and prognosis. MicroRNAs (miRNAs) are small sequences of non-coding single-stranded RNA that regulate gene expression and play an essential role in developing many pathologies, including renal diseases. This study aimed to evaluate the expression of Cytokine-Chemokine molecules (IL-1α/1β/4/6/10, INF-γ, MIP-1α, MCP-1, RANTES, and TGF β1/2/3) and inflammation-related miRNAs to evidence the possible renal mechanisms involved in subchronic exposure to F. Total protein and miRNAs were obtained from the renal cortex of male Wistar rats exposed to 0, 15 and 50 mg NaF/L through drinking water during 40 and 80 days. In addition, cytokines-chemokines were analyzed by multiplexing assay, and a panel of 77 sequences of inflammatory-related miRNAs was analyzed by qPCR. The results show that cytokines-chemokines expression was concentration- and time-dependent with F, where the 50 mg NaF/L were the main altered groups. The miRNAs expression resulted in statistically significant differences in thirty-four miRNAs in the 50 mg NaF/L groups at 40 and 80 days. Furthermore, a molecular interaction network analysis was performed. The relevant pathways modified by subchronic exposure to fluoride were related to extracellular matrix-receptor interaction, Mucin type O-glycan biosynthesis, Gap junction, and miRNAs involved with renal cell carcinoma. Thus, F-induced cytokines-chemokines suggest subchronic inflammation; detecting miRNAs related to cancer and proliferation indicates a transition from renal epithelium to pathologic tissue after fluoride exposure.

The Clinical and Molecular Features in the VHL Renal Cancers; Close or Distant Relatives with Sporadic Clear Cell Renal Cell Carcinoma?

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited cancer syndrome caused by germline mutations in the VHL tumor suppressor gene, characterized by the susceptibility to a wide array of benign and malign neoplasms, including clear-cell renal cell carcinoma. Moreover, VHL somatic inactivation is a crucial molecular event also in sporadic ccRCCs tumorigenesis. While systemic biomarkers in the VHL syndrome do not currently play a role in clinical practice, a new promising class of predictive biomarkers, microRNAs, has been increasingly studied. Lots of pan-genomic studies have deeply investigated the possible biological role of microRNAs in the development and progression of sporadic ccRCC; however, few studies have investigated the miRNA profile in VHL patients. Our review summarize all the new insights related to clinical and molecular features in VHL renal cancers, with a particular focus on the overlap with sporadic ccRCC.

HIF-1α Induces HECTD2 Up-Regulation and Aggravates the Malignant Progression of Renal Cell Cancer via Repressing miR-320a

Renal cell carcinoma (RCC) is a frequent malignancy of the urinary system. It has been found that hypoxia mediates the malignant evolvement of RCC. Here, we probe the impact and potential mechanism of HECT domain E3 ubiquitin-protein ligase 2 (HECTD2) and HIF-1α on regulating RCC evolvement. RCC tissues and adjacent normal tissues were collected, and the association between the expression profiles of HECTD2 and HIF-1α and the clinicopathological features was analyzed. Additionally, we constructed HECTD2/HIF-1α overexpression and knockdown models in RCC cell lines to ascertain the impacts of HECTD2 and HIF-1α on RCC cell proliferation, apoptosis, migration, and growth in vivo. We applied bioinformatics to predict the upstream miRNA targets of HECTD2. Meanwhile, RNA immunoprecipitation (RIP), and the dual-luciferase reporter assays were employed to clarify the targeting association between HECTD2 and miR-320a. The effect of miR-320a on HECTD2-mediated RCC progression was investigated. The results suggested that both HIF-1α and HECTD2 were up-regulated in RCC (compared with adjacent non-tumor tissues), and they had positive relationship. Moreover, higher level of HECTD2 and HIF-1α is associated with poorer overall survival of RCC patients. HECTD2 overexpression heightened RCC cell proliferation and migration, and weakened cell apoptosis. On the other hand, the malignant phenotypes of RCC cells were signally impeded by HECTD2 or HIF-1α knockdown. Moreover, miR-320a targeted the 3'-untranslated region of HECTD2 and suppressed HECTD2 expression. The rescue experiments showed that miR-320a restrained HECTD2-mediated malignant progression in RCC, while up-regulation of HIF-1α hampered miR-320a expression. Collectively, HIF-1α mediated HECTD2 up-regulation and aggravated RCC progression by attenuating miR-320a.

miR‑133b affects cell proliferation, invasion and chemosensitivity in renal cell carcinoma by inhibiting the ERK signaling pathway

Renal cell carcinoma has the highest incidence rate of cancer types in the urinary system. Moreover, microRNAs (miRNA) have been closely associated with numerous types of tumor. The present study aimed to investigate the effects of miRNA (miR)-133b on the proliferation, invasion and chemosensitivity of renal cell carcinoma cells, and to determine whether its mechanism was regulated by the ERK signaling pathway. Both renal cell carcinoma and adjacent healthy tissues from 60 patients, in addition to renal cell carcinoma lines, ACHN, Caki-1, A-498 and 786-O, and 293 cells, were used in this study. miR-133b expression was measured from renal cell carcinoma, adjacent healthy tissues and renal cell carcinoma cell lines by reverse transcription-quantitative PCR. Cells were transfected with miR-133b mimic to achieve miR-133b overexpression. The proliferative, migratory and invasive ability of the cells were evaluated using MTT, wound healing and Matrigel assays, respectively, and flow cytometry was used to detect the apoptotic rate. Following treatment with an ERK inhibitor, U0126, and activator, LM22B-10, western blotting was used to detect the expression of related proteins and the activity of the ERK signaling pathway. The overexpression of miR-133b significantly inhibited cell proliferation, migration and invasion, whilst inducing apoptosis and increasing the drug sensitivity of renal cell carcinoma cells to cisplatin, docetaxel and doxorubicin. The miR-133b mimic also increased the protein expression levels of Bax and decreased the expression levels of matrix metalloproteinase (MMP)-2, MMP-9, ATP-binding cassette subfamily G2, P-glycoprotein, Bcl-2 and proliferating cell nuclear antigen, as well as the phosphorylation of ERK (P<0.05). The administration of the U0216 inhibitor demonstrated similar effects to miR-133b overexpression, and there was no significant difference compared with the miR-133b mimic transfection (P>0.05). However, the overexpression of miR-133b combined with LM22B-10 treatment weakened the anticancer effects of miR-133b mimic transfection (P<0.05). In conclusion, miR-133b overexpression was observed to inhibit the proliferation, migration and invasion of renal cell carcinoma cells and improve chemotherapeutic sensitivity; it was suggested that the mechanism maybe related to the inhibition of ERK1/2 phosphorylation and thus decreased ERK signaling pathway activity.

MicroRNA-200c-3p/ZEB2 loop plays a crucial role in the tumor progression of prostate carcinoma

Background

The microRNA (miRNA) miR-200c-3p is involved in the tumorigenesis and progression of a variety of cancers. However, the underlying regulatory role of miR-200c-3p in prostate cancer (PCa) remains unclear.

Methods

Online databases including Oncomine, Linkedomics and StarBase were used to investigate the clinical significance of miR-200c-3p, along with associated gene targets. PCa tissues and adjacent normal tissues were used for the detection of miR-200c-3p expression. A lentivirus overexpressing miR-200c-3p was constructed and transfected into PC3 and DU145 cells. Cell formation of proliferation, migration, and invasion were determined by cell viability and colony-formation assay, wound healing assay, and Matrigel invasion assay, respectively. Epithelial-mesenchymal transition (EMT)-associated markers were determined by qRT-PCR and Western blot. A luciferase reporter assay was performed to determine the direct relationship of miR-200c-3p and ZEB2. The tumor-suppressive role of miR-200c-3p was further confirmed by a xenograft tumor model and immunohistochemical (IHC) staining.

Results

Online database analyses showed that miR-200c-3p was associated with pathologic T and N stage in PCa, and miR-200c-3p was downregulated in PCa tissues. Overexpression of miR-200c-3p was considered a tumor suppressor and was found to significantly suppress the formation of migration and invasion in PCa cells via repression of E-cadherin-induced EMT. The bioinformatic database indicated that ZEB2 has a significant correlation with miR-200c-3p and was upregulated in PCa tissues. Further, ZEB2 expression was suppressed by the upregulation of miR-200c-3p and was identified as a direct target of miR-200c-3p. In addition, repression of ZEB2 could restore the levels of miR-200c-3p in PCa cells in turn, suggesting a potential negative loop between miR-200c-3p and ZEB2. miR-200c-3p also had an antitumor effect by negatively regulating ZEB2 in a xenograft mouse model.

Conclusions

Taken together, the results of our study demonstrated the novel regulatory loop of miR-200c-3/ZEB2 in PCa progression, providing effective therapeutic strategies for PCa in the future.

miR-216a-5p acts as an oncogene in renal cell carcinoma

MiR-216a-5p has been acknowledged as an oncogene and is known to be involved in the progression and metastasis of numerous cancer subtypes. However, the potential role of miR-216a-5p in renal cell carcinoma (RCC) remains to be elucidated. In the present study, reverse transcription-quantitative polymerase chain reaction was performed to detect the expression levels of miR-216a-5p in RCC tissues. Cell counting kit-8, MTT, wound scratch, Transwell and flow cytometric assays were performed to establish the biological functions of miR-216a-5p in RCC. Functional experiments demonstrated that the expression of miR-216a-5p was upregulated in RCC (P<0.05) and miR-216a-5p mimics promoted cellular proliferation, viability and motility, and suppressed apoptosis. Conversely, miR-216a-5p inhibitor suppressed cellular proliferation, viability, motility and induced apoptosis. Based on these findings, it was concluded that miR-216a-5p may function as an oncogene in RCC. MiR-216a-5p target genes need to be explored and the potential of miR-216a-5p to be used as a diagnostic or a prognostic biomarker for RCC needs to be validated by future research.

MicroRNA-100 suppresses human gastric cancer cell proliferation by targeting CXCR7

microRNAs (miRs) are a class of small non-coding RNAs that have been demonstrated to have a crucial role in tumorigenesis of human cancers, including gastric cancer (GC). Previous results have established that miR-100 participated in the development of GC; however, the underlying mechanism remains largely unknown. The preesent study utilized reverse transcription-quantitative polymerase chain reaction to analyze the expression of miR-100 in GC tissues and adjacent normal tissues. The present results indicated that the expression of miR-100 was downregulated in GC tissues when compared to the adjacent normal tissues. Furthermore, low miR-100 expression was observed to be associated with lymph node metastasis, tumor diameter and tumor stage. In addition, Kaplan-Meier analysis revealed that patients with low miR-100 expression tended to have a shorter overall survival. The miR-100 was further identified as an independent prognostic factor for overall survival. Notably, the levels of chemokine (CXC motif) receptor 7 (CXCR7) were inversely correlated with miR-100 in GC cell lines. Furthermore, miR-100 overexpression or CXCR7 depletion decreased in vitro GC cell proliferation. Bioinformatics analysis indicated that miR-100 may bind to the 3'-untranslated region of CXCR7 to prevent the initiation of protein translation. Thus, miR-100 may function as a tumor suppressor in GC, partly by regulating the expression of CXCR7, and the regulation of miR-100 expression may be a potential strategy for the treatment of GC patients.

Serum microRNA Expression Profiling: Potential Diagnostic Implications of a Panel of Serum microRNAs for Clear Cell Renal Cell Cancer

OBJECTIVE

To study the expression profiles of 5 microRNAs in tissue and serum of patients with clear cell renal cell cancer (ccRCC) and evaluate their diagnostic and prognostic potential.

MATERIALS AND METHODS

We prospectively analyzed 30 patients of histologically proven ccRCC and collected 3 mL of serum preoperatively and small pieces of tumor and adjacent non-tumor renal tissue intraoperatively. Control serum samples were obtained from 15 patients of non-renal benign diseases. We analyzed 5 miRNAs-miR-34a, miR-141, miR-200c, miR-1233, and miR-21-2. Freshly collected samples were immediately frozen in liquid nitrogen and total RNA was extracted. cDNA was synthesized by reverse transcription, and quantitative polymerase chain reaction was performed to determine relative miRNA expression.

RESULTS

In the renal tissue and serum samples, 3 out of 5 miRNAs were differentially expressed; that is, the expression levels of miR-34a and miR-141 were significantly decreased, whereas that of miR-1233 was significantly increased. Serum miR-34a, miR-141, and miR-1233 were able to diagnose ccRCC with a sensitivity of 80.76%, 75%, and 93.33%, and specificity of 80%, 73.33%, and 100%, respectively, as compared to histopathology. Using a panel of 2 serum miRNAs (miR-141 and miR-1233) ccRCC can be diagnosed with 100% sensitivity and 73.3% specificity.

CONCLUSION

miRNAs are differentially expressed in serum of patients with ccRCC and can be used to diagnose ccRCC with high sensitivity and specificity. Diagnostic sensitivity can be further improved by using a panel of miRNAs and has the potential to serve as novel diagnostic markers of ccRCC.

WITHDRAWN: MicroRNA-99a Suppresses Proliferation, Migration, Invasion and Induces G1-phase Cell Cycle Arrest via Targeting Insulin-like Growth Factor 1 Receptor Pathway in Renal Cell Carcinoma 786-0 and OS-RC-2 Cells

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Dicer suppresses the malignant phenotype in VHL-deficient clear cell renal cell carcinoma by inhibiting HIF-2α

Both the von Hippel-Lindau (VHL)/hypoxia-inducible factor (HIF) pathway and microRNA (miRNA) regulation are important mechanisms underlying the development and progression of clear cell renal cell carcinoma (ccRCC). Here we demonstrate that VHL deficiency leads to downregulation of Dicer and, in turn, defects in the miRNA biogenesis machinery in ccRCCs. Dicer inhibited expression of HIF-2α, which was a direct target of Dicer-dependent miR-182-5p in VHL-deficient ccRCCs. Ectopic Dicer expression in VHL-deficient ccRCCs suppressed tumor growth and angiogenesis by inhibiting HIF-2α both in vitro and in vivo. Reduced Dicer mRNA levels served as an independent prognostic factor for poor survival in patients with VHL-deficient ccRCC. Our results indicate that downregulation of Dicer in VHL-deficient ccRCCs contributes to high levels of HIF-2α and a malignant phenotype, which suggests Dicer could be a useful therapeutic target for managing this disease.

miR-206 inhibits renal cell cancer growth by targeting GAK

Renal cell cancer (RCC) remains one of the most lethal types of cancer in adults. MicroRNAs (miRNAs) play key roles in the pathogenesis of RCC. The role of miR-206 in RCC has not been fully understood. The purpose of this study was to examine the role of miR-206 in the regulation of proliferation and metastasis of RCC and the possible mechanism. miR-206 expression was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in RCC cell lines (786-O and OS-RC-2 cells) and clinical samples. MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] method, colony formation and transwell assay were used to detect the tumor-suppressing ability of miR-206 in RCC. Luciferase assay was performed to verify the precise target of miR-206. The results showed that the expression of miR-206 was significantly down-regulated in RCC tissues and cells. The expression level of cyclin G-associated kinase (GAK), a master regulator of tumor proliferation and metastasis, was up-regulated with the decrease in miR-206 in RCC tissues as well as RCC cell lines. In addition, the miR-206 inhibitor promoted the proliferation, migration and invasion of 786-O and OS-RC-2 cells. Bioinformatics combined with luciferase and Western blot assays revealed that miR-206 inhibited the expression of GAK. Moreover, miR-206 regulates RCC cell growth partly through targeting GAK. Our study indicated that miR-206 functions as a tumor suppressor in regulating the proliferation, migration and invasion of RCC by directly targeting GAK, and it holds promises as a potential therapeutic target for RCC.

Renal Carcinogenesis, Tumor Heterogeneity, and Reactive Oxygen Species: Tactics Evolved

SIGNIFICANCE

The number of kidney cancers is growing 3-5% each year due to unknown etiologies. Intra- and inter-tumor mediators increase oxidative stress and drive tumor heterogeneity. Recent Advances: Technology advancement in state-of-the-art instrumentation and methodologies allows researchers to detect and characterize global landscaping modifications in genes, proteins, and pathophysiology patterns at the single-cell level.

CRITICAL ISSUES

We postulate that the sources of reactive oxygen species (ROS) and their activation within subcellular compartments will change over a timeline of tumor evolvement and contribute to tumor heterogeneity. Therefore, the complexity of intracellular changes within a tumor and ROS-induced tumor heterogeneity coupled to the advancement of detecting these events globally are limited at the level of data collection, organization, and interpretation using software algorithms and bioinformatics.

FUTURE DIRECTIONS

Integrative and collaborative research, combining the power of numbers with careful experimental design, protocol development, and data interpretation, will translate cancer biology and therapeutics to a heightened level or leave the abundant raw data as stagnant and underutilized. Antioxid. Redox Signal. 25, 685-701.

MicroRNAs as prognostic molecular signatures in renal cell carcinoma: a systematic review and meta-analysis

This is a systematic review of studies investigating the prognostic value of different microRNAs (miRs) in renal cell carcinoma (RCC). Twenty-seven relevant studies were identified, with a total of 2578 subjects. We found that elevated expression of miR-21, miR-1260b, miR-210, miR-100, miR-125b, miR-221, miR-630, and miR-497 was associated with a poor prognosis in RCC patients. Conversely, decreased expression of miR-106b, miR-99a, miR-1826, miR-215, miR-217, miR-187, miR-129–3p, miR-23b, miR-27b, and miR-126 was associated with a worse prognosis. We performed meta-analyses on studies to address the prognostic value of miR-21, miR-126, miR-210, and miR-221. This revealed that elevated miR-21 expression was associated with shorter overall survival (OS; hazard ratio [HR], 2.29; 95% confidence interval [CI], 1.28–4.08), cancer specific survival (CSS; HR, 4.16; 95% CI, 2.49–6.95), and disease free survival (DFS; HR, 2.15; 95% CI, 1.16–3.98). The decreased expression of miR-126 was associated with shorter CSS (HR, 0.35; 95% CI, 0.15–0.85), OS (HR, 0.45; 95% CI, 0.30–0.69), and DFS (HR 0.30; 95% CI, 0.18–0.50). Our comprehensive systematic review reveals that miRs, especially miR-21 and miR-126, could be promising prognostic markers and useful therapeutic targets in RCC.

Let-7a inhibits tumor cell growth and metastasis by directly targeting RTKN in human colon cancer

Colorectal cancer (CRC) is the third most common cancer worldwide, with high morbidity. MicroRNAs (miRNAs) are endogenous small RNAs that play important roles in regulating multiple biological and pathologic processes. The differential expression of miRNAs in CRC was first reported in 2003. Accumulated evidence indicates that lethal-7a (let-7a, miRNA) generally functions as a tumor suppressor in several human cancers. However, the role of let-7a in human colon cancer remains unclear. The aim of this study was to investigate the biological functions of let-7a and its potential role in colon cancer. We first discovered that let-7a level was significantly decreased in colon cancer tissues and cell lines (HT-29, HCT-116, LoVo, SW480, and SW620). To explore the effects of let-7a on colon cancer, let-7a over-expressed HCT-116 and SW620 cells were constructed. Further studies demonstrated that over-expressed let-7a could remarkably inhibit HCT-116 and SW620 cell growth and metastasis by directly down-regulating Rhotekin (RTKN). When RTKN was reintroduced into let-7a mimic transfected HCT-116 or SW620 cells, the inhibition effects of let-7a on colon cancer cell growth and metastasis were markedly reversed. In conclusion, our research shows that let-7a can inhibit tumor cell growth and metastasis by directly targeting RTKN in human colon cancer.

MicroRNA-27a functions as a tumor suppressor in renal cell carcinoma by targeting epidermal growth factor receptor

Numerous studies have suggested that microRNAs (miRNAs) are vital in the development of various types of human cancers, including renal cell carcinoma (RCC), and the regulation of tumor progression and invasion. However, the effect of miRNA-27a (miR-27a) on the tumorigenesis of RCC is unclear. The aim of the present study was to investigate the function of miR-27a and identify its possible target genes in RCC cells. In the present study, cell proliferation, migration and invasion and the percentage of apoptotic cells were detected by methylthiazol tetrazolium assays, Annexin V analysis, wound-healing assays and Transwell invasion assays. Western blot analysis was performed to validate the protein expression level and assess whether the epidermal growth factor receptor (EGFR) was a target gene of miR-27a. A tumor xenograft animal model was used to detect the role of miR-27a on RCC cell growth in vivo. The present study demonstrated that miR-27a significantly suppressed human RCC 786-O cell proliferation and induced cell apoptosis. Restoration of miR-27 also resulted in 786-O cell migration and invasion inhibition. Furthermore, upregulated miR-27a attenuated RCC tumor growth in the tumor xenograft animal model. The present results suggested that miR-27a functions as a tumor suppressor in RCC. The western blot analysis assay revealed that EGFR was a novel target of miR-27a. The growth suppression of RCC cells was attributed partly to the downregulation of the cell cycle by ERFR inhibition. The present findings may aid in the understanding of the molecular mechanism of miR-27a in the tumorigenesis of RCC, and may provide novel diagnostic and therapeutic options for RCC.

MicroRNA-22 is downregulated in clear cell renal cell carcinoma, and inhibits cell growth, migration and invasion by targeting PTEN

MicroRNA (miR)-22 has previously been reported to be frequently downregulated in certain types of cancer. The present study examined the expression and effects of miR-22 in renal cell carcinoma (RCC). The results indicated that miR‑22 was downregulated in tumor tissue from patients with RCC. In addition, lower miR‑22 expression levels were associated with histological grade, tumor stage and lymph node metas-tasis. Following transfection of RCC cells with miR‑22, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell migration, cell invasion and luciferase assays, and western blotting were conducted. The results demonstrated that miR‑22 was able to inhibit cell proliferation, migration and invasion in 786‑O and A498 cells. Furthermore, the results indicated that miR‑22 may directly target phosphatase and tensin homolog (PTEN) in RCC. In conclusion, the present study suggested that the miR-22/PTEN axis may be considered a novel therapeutic target in RCC. These findings may be beneficial for the development of an effective therapy against RCC.

MicroRNAs in the Pathogenesis of Renal Cell Carcinoma and Their Diagnostic and Prognostic Utility as Cancer Biomarkers

Purpose

To provide information about the role of microRNAs in the pathogenesis of renal cell carcinoma (RCC) and their diagnostic and prognostic utility as cancer biomarkers.

Methods

A literature search was performed in the PubMed and Web of Science databases using the keywords “renal cancer/renal cell carcinoma/kidney cancer” and “miR*/miRNA*/microRNA*”. Articles dealing with the role of miRNAs in the pathogenesis of RCC, diagnostic miRNAs and prognostic miRNAs were separated.

Results

MiRNAs act both as oncogenes and tumor suppressors. They regulate apoptosis, cell growth, migration, invasion, proliferation, colony formation and angiogenesis through target proteins involved in several signaling pathways, and they are involved in key pathogenetic mechanisms such as hypoxia (HIF/VHL dependent) and epithelial-to-mesenchymal transition. Differentially expressed miRNAs can discriminate either tumor tissue from healthy renal tissue or different RCC subtypes. Circulating miRNAs are promissing as diagnostic biomarkers of RCC. Information about urinary miRNAs associated with RCC is sparse. Detection of a relapse is another implication of diagnostic miRNAs. The expression profiles of several miRNAs correlate with the prognosis of RCC patients. Comparison between primary tumor tissue and metastasis may help identify high-risk primary tumors. Finally, response to target therapy can be estimated thanks to differences in miRNA expression in tissue and serum of therapy-resistant versus therapy-sensitive patients.

Conclusions

Our understanding of the role of microRNAs in RCC pathogenesis has been increasing dramatically. Identification and validation of their gene targets may have direct impact on developing microRNA-based anticancer therapy. Several microRNAs can serve as diagnostic and prognostic biomarkers.

Diagnostic and prognostic accuracy of miR-21 in renal cell carcinoma: a systematic review protocol

INTRODUCTION

Renal cell carcinoma (RCC) is the most common neoplasm in adult kidneys. One of the most important unmet medical needs in RCC is a prognostic biomarker to enable identification of patients at high risk of relapse after nephrectomy. New biomarkers can help improve diagnosis and hence the management of patients with renal cancer. Thus, this systematic review aims to clarify the prognostic and diagnostic accuracy of miR-21 in patients with RCC.

METHODS AND ANALYSIS

We will include observational studies evaluating the diagnostic and prognostic roles of miR-21 in patients with renal cancer. The index test and reference standards should ideally be performed on all patients. We will search PubMed, SCOPUS and ISI Web of Science with no restriction of language. The outcome will be survival measures in adult patients with RCC. Study selection and data extraction will be performed by two independent reviewers. QUADAS-1 will be used to assess study quality. Publication bias and data synthesis will be assessed by funnel plots and Begg's and Egger's tests using Stata software V.11.1.

ETHICS AND DISSEMINATION

No ethical issues are predicted. These findings will be published in a peer-reviewed journal and presented at national and international conferences.

TRAIL REGISTRATION NUMBER

This systematic review protocol is registered in the PROSPERO International Prospective Register of Systematic Reviews, registration number CRD42015025001.

The role of microRNAs expression in laryngeal cancer

MicroRNAs (miRs, miRs) is a class of small non-coding RNAs, which posttranscriptionally regulate gene expression. Deregulated miRs are frequently obseved in patients with laryngeal cancer. In addition, numerous studies have showed miRs play significant roles in the pathogenesis of laryngeal cancer through regulating tumor cell proliferation, metastasis, invasion and apoptosis. miR can play either an oncogenic or tumor suppressive role in laryngeal cancer. In our review, we summarize the recent researches on laryngeal cancer-associated miRs, focusing on their role in the pathogenesis of laryngeal cancer. As changes in the levels of specific miRs in tissues or serum associate with diagnosis and prognosis of patients, we will also discuss the potential use of miRs in laryngeal cancer diagnosis and prognosis. Furthermore, supplementation of oncomiRs or inhibition of tumor suppressive miRs in vivo may be future therapeutic strategy for laryngeal cancer.

Clinicians' Real World Perceptions of Pre-Nephrectomy Diagnostic Biopsy Performance as a Driver of Reduction in Unnecessary Surgeries in Renal Tumors

Operative removal of oncocytomas is generally unnecessary, but not infrequent in the context of renal masses. The infrequent use of pre-nephrectomy biopsies is a function of historical limitations of histopathological differential diagnosis in this setting. Assessment of clinicians’ receptiveness to a novel molecular diagnostic approach to this challenge was undertaken by means of a survey vehicle administered to 102 practicing urologists and pathologists who met inclusion criteria related to their actual clinical activity. Survey results supported the previously reported observations on misdiagnosis with urologists’ reported rates of 25% inconclusive results, and an additional 17% disagree with the final surgical diagnosis. The self-reported rate of 9% for pre-operative biopsies was comparable to prior reports, but 39% of urologists who are not currently performing pre-operative biopsies expressed interest in introducing them into their practice for this purpose with an improved diagnostic. Almost all urologists (94%) felt it important not to resect benign oncocytomas and 62% indicated they would use a test which improved the ability to sub-type renal tumors pre-operatively. The level of performance benchmark of the unidentified prototypic microRNA-based diagnostic as reported previously in the literature was deemed sufficient to change care in these cases by 73%. Overall they predicted a 38% rate of biopsies and resulting increases in decisions to forgo nephrectomy or to perform only partial nephrectomy. Pathologists also expressed support for the use of this technology in the context of inadequate specimens and for improved sub-typing of these tumors in inconclusive cases.

miR-210 is a prognostic marker in clear cell renal cell carcinoma

Accurate assessment of prognosis of clear cell renal cell carcinoma (ccRCC) is key in optimizing management plans to fit individual patient needs. miRNAs are short noncoding single-stranded RNAs that control the expression of target genes and may act as cancer biomarkers. We analyzed the expression of miR-210 in 276 cases of primary ccRCC and compared its expression in 40 pairs of adjacent normal and cancerous tissues. We assessed its expression in primary and metastatic tumors, in the common RCC subtypes, and the benign oncocytoma. The results were validated with an independent data set from The Cancer Genome Atlas. miR-210 was significantly overexpressed in ccRCC compared with normal kidney. miR-210(+) patients had a statistically higher chance of disease recurrence [hazard ratio (HR), 1.82; P = 0.018] and shorter overall survival (HR, 2.46; P = 0.014). In multivariate analysis, miR-210 lost its statistically significant association with shorter disease-free survival and overall survival after adjusting for tumor size and tumor, node, metastasis stage. Papillary RCC showed comparable miR-210 overexpression, whereas decreased up-regulation was seen in chromophobe RCC and oncocytoma. A number of predicted targets that might be involved in carcinogenesis and aggressive tumor behavior were identified. miR-210 is a potential therapeutic target and independent marker of poor prognosis of ccRCC.

Tumor miR-125b predicts recurrence and survival of patients with clear-cell renal cell carcinoma after surgical resection

The present study aims to evaluate the impact of tumor microRNA-125b (miR-125b) on recurrence and survival of patients with clear-cell renal cell carcinoma (ccRCC) following surgery. We retrospectively enrolled 276 patients (200 in the training cohort and 76 in the validation cohort) with ccRCC undergoing nephrectomy at a single institution. Clinicopathologic features, cancer-specific survival (CSS) and recurrence-free survival (RFS) were recorded. Tumor miR-125b levels were assessed by in situ hybridization (ISH) in specimens of patients. The Kaplan–Meier method was applied to compare survival curves. Cox regression models were used to analyze the impact of prognostic factors on CSS and RFS. A concordance index (C-index) was calculated to assess predictive accuracy. In both cohorts, tumor miR-125b positively correlated with Fuhrman grade. High tumor miR-125b indicated poor survival and early recurrence for patients with ccRCC, especially with advanced stage disease. After multivariable adjustment, tumor miR-125b was identified as an independent adverse prognostic factor for survival and recurrence. The predictive accuracy of traditional TNM and UCLA Integrated Staging System prognostic models was improved when tumor miR-125b was added. The results showed that tumor miR-125b is a potential independent adverse prognostic biomarker for recurrence and survival of patients with ccRCC after nephrectomy.

Identification of tubular injury microRNA biomarkers in urine: comparison of next-generation sequencing and qPCR-based profiling platforms

Background

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate protein levels post-transcriptionally. miRNAs play important regulatory roles in many cellular processes and have been implicated in several diseases. Recent studies have reported significant levels of miRNAs in a variety of body fluids, raising the possibility that miRNAs could serve as useful biomarkers. Next-generation sequencing (NGS) is increasingly employed in biomedical investigations. Although concordance between this platform and qRT-PCR based assays has been reported in high quality specimens, information is lacking on comparisons in biofluids especially urine. Here we describe the changes in miRNA expression patterns in a rodent model of renal tubular injury (gentamicin). Our aim is to compare RNA sequencing and qPCR based miRNA profiling in urine specimen from control and rats with confirmed tubular injury.

Results

Our preliminary examination of the concordance between miRNA-seq and qRT-PCR in urine specimen suggests minimal agreement between platforms probably due to the differences in sensitivity. Our results suggest that although miRNA-seq has superior specificity, it may not detect low abundant miRNAs in urine samples. Specifically, miRNA-seq did not detect some sequences which were identified by qRT-PCR. On the other hand, the qRT-PCR analysis was not able to detect the miRNA isoforms, which made up the majority of miRNA changes detected by NGS.

Conclusions

To our knowledge, this is the first time that miRNA profiling platforms including NGS have been compared in urine specimen. miRNAs identified by both platforms, let-7d, miR-203, and miR-320, may potentially serve as promising novel urinary biomarkers for drug induced renal tubular epithelial injury.

microRNA-133b downregulation and inhibition of cell proliferation, migration and invasion by targeting matrix metallopeptidase-9 in renal cell carcinoma

microRNA (miRNA)-133b has been revealed to be downregulated in head and neck/oral, bladder, human non-small cell lung, colorectal and esophageal squamous cell cancer. The present study examined the expression of miR-133b in renal cell carcinoma (RCC) cell lines and the effects of miRNA-133b on RCC cell proliferation, migration and invasion. Quantitative polymerase chain reaction was used to detect the expression of miR-133b in RCC cell lines. Following transfection of miR-133b, the expression of miR-133b was examined and a cell viability assay, cell migration assay, cell invasion assay, western blot analysis and luciferase assay were conducted in RCC cell lines. The present study revealed that miRNA‑133b was downregulated and inhibited cell proliferation, migration and invasion in 786-O and A498 cells. In addition, to the best of our knowledge, the present study provided the first evidence that miRNA-133b may directly target matrix metallopeptidase 9 (MMP-9) in RCC. The present study also provided evidence that miRNA-133b suppresses cell proliferation, migration and invasion by targeting MMP-9 in RCC cell lines. These results suggested that miRNA-133b may be used for the development of novel molecular markers and therapeutic approaches to inhibit the metastasis of RCC.

miR-199a-3p inhibits hepatocyte growth factor/c-Met signaling in renal cancer carcinoma

MicroRNAs (miRNAs) are a class of small non-coding RNAs that bind protein-coding mRNAs and negatively regulate protein expression by translation repression or mRNA cleavage. Accumulating evidence suggests that miRNAs are involved in cancer development and progression, acting as either tumor suppressors or oncogenes. It has been shown that miR-199a-3p was significantly down-regulated in several types of cancers. However, its role and relevance in renal cell carcinoma (RCC) are still largely unknown. Here, we show that miR-199a-3p is significantly down-regulated in human RCC primary tumors and cell lines compared to their non-tumor counterparts. Moreover, the down-regulation of miR-199a-3p is correlated with the histological grade and TNM (tumor-lymph node-metastasis) stage of RCC. Reintroducing miR-199a-3p in RCC cell lines 769-P and Caki-1 inhibited cell proliferation and caused G1 phase arrest. We found that c-Met was up-regulated in RCC cell lines and its expression could be repressed by miR-199a-3p. Moreover, c-Met was up-regulated in RCC primary tumors and reversely correlated with miR-199a-3p expression in the same paired RCC tissues. Reintroducing miR-199a-3p inhibited c-Met expression and led to attenuated activation of c-Met downstream signaling pathways including STAT3, mTOR and ERK1/2. We found that the concentrations of serum hepatocyte growth factor (HGF), the ligand of c-Met receptor, were significantly elevated in RCC patients compared to healthy persons. In addition, HGF treatment could promote proliferation of RCC cells, and the increased cell proliferation was abrogated by miR-199a-3p. Our findings indicated that miR-199a-3p target HGF/c-Met signaling pathway which is crucial for RCC development and suggest that miR-199a-3p may serve as a potential target miRNA for RCC therapy.

Hypoxia-induced downregulation of miR-30c promotes epithelial-mesenchymal transition in human renal cell carcinoma

MicroRNAs (miRNAs), which negatively regulate protein expression by binding protein-coding mRNAs, have been integrated into cancer development and progression as either oncogenes or tumor suppressor genes. miR-30c was reported to be downregulated in several types of cancer. However, its role in human renal cell carcinoma (RCC) remains largely unknown. Here, we show that miR-30c is significantly downregulated in human RCC tissues and cell lines. We found that miR-30c downregulation could be induced by hypoxia in RCC cells in a hypoxia-inducible factors (HIFs) dependent manner. Repression of miR-30c through its inhibitor resulted in reduction of E-cadherin production and promotion of epithelial-mesenchymal transition (EMT), while overexpression of miR-30c inhibited EMT in RCC cells. We identified Slug as a direct target of miR-30c in RCC cells. Slug was upregulated in RCC tissues and its expression could be induced by hypoxia, which is consistent with downregulation of miR-30c by hypoxia. Forced overexpression of Slug in 786-O cells reduced E-cadherin production, and promoted EMT as well as cell migration. Moreover, Slug overexpression abrogated the inhibitory role of miR-30c in regulating EMT and cell migration, indicating miR-30c regulates EMT through Slug in RCC cells. Our findings propose a model that hypoxia induces EMT in RCC cells through downregulation of miR-30c, which leads to subsequent increase of Slug expression and repression of E-cadherin production, and suggest a potential application of miR-30c in RCC treatment.

MicroRNA profile: a promising ancillary tool for accurate renal cell tumour diagnosis

Background:

Renal cell tumours (RCTs) are clinically, morphologically and genetically heterogeneous. Accurate identification of renal cell carcinomas (RCCs) and its discrimination from normal tissue and benign tumours is mandatory. We, thus, aimed to define a panel of microRNAs that might aid in the diagnostic workup of RCTs.

Methods:

Fresh-frozen tissues from 120 RCTs (clear-cell RCC, papillary RCC, chromophobe RCC (chRCC) and oncocytomas: 30 cases each), 10 normal renal tissues and 60 cases of ex-vivo fine-needle aspiration biopsies from RCTs (15 of each subtype validation set) were collected. Expression levels of miR-21, miR-141, miR-155, miR-183 and miR-200b were assessed by quantitative reverse transcription–PCR. Receiver operator characteristic curves were constructed and the areas under the curve were calculated to assess diagnostic performance. Disease-specific survival curves and a Cox regression model comprising all significant variables were computed.

Results:

Renal cell tumours displayed significantly lower expression levels of miR-21, miR-141 and miR-200b compared with that of normal tissues, and expression levels of all miRs differed significantly between malignant and benign RCTs. Expression analysis of miR-141 or miR-200b accurately distinguished RCTs from normal renal tissues, oncocytoma from RCC and chRCC from oncocytoma. The diagnostic performance was confirmed in the validation set. Interestingly, miR-21, miR-141 and miR-155 expression levels showed prognostic significance in a univariate analysis.

Conclusion:

The miR-141 or miR-200b panel accurately distinguishes RCC from normal kidney and oncocytoma in tissue samples, discriminating from normal kidney and oncocytoma, whereas miR-21, miR-141 and miR-155 convey prognostic information. This approach is feasible in fine-needle aspiration biopsies and might provide an ancillary tool for routine diagnosis.

Genome-wide microRNA expression profiling in idiopathic non-obstructive azoospermia: significant up-regulation of miR-141, miR-429 and miR-7-1-3p

STUDY QUESTION

What is the profile of miRNAs in seminal plasma of patients with non-obstructive azoospermia (NOA)?

SUMMARY ANSWER

miR-141, miR-429 and miR-7-1-3p are significantly increased in seminal plasma of patients with NOA compared with fertile controls.

WHAT IS KNOWN ALREADY

There is currently an urgent need to develop a noninvasive diagnostic test for NOA. Altered microRNA (miRNA) profiles have been proposed as potential biomarkers for the diagnosis of disease states.

STUDY DESIGN, SIZE, DURATION

A total of 200 subjects (n = 100 for NOA, n = 100 for fertile control) were recruited to participate in this study. Recruitment took place from May 2008 to June 2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We employed a strategy consisting of initial screening by TaqMan Low Density Array then further validation with a TaqMan quantitative RT-PCR assay. Validation of the profiling results was conducted in two independent phases. In addition, the expression of the three validated seminal plasma miRNAs (sp-miRNAs) was examined in testicular tissues of patients with NOA and of fertile controls. Methylation status and functional analyses were also performed for the identified sp-miRNAs.

MAIN RESULTS AND THE ROLE OF CHANCE

miR-141, miR-429 and miR-7-1-3p were significantly increased in seminal plasma of patients with NOA compared with fertile controls. As sensitive and specific biomarkers, the profiling of these three identified sp-miRNAs provides a novel noninvasive, semen-based test for NOA diagnosis. The methylation status of these sp-miRNAs was inversely associated with their expression patterns. Additionally, we found that Cbl and Tgfβ2 were down-regulated by miR-141, while Rb1 and Pik3r3 were down-regulated by miR-7-1-3p.

LIMITATIONS, REASONS FOR CAUTION

miRNA expression profile was investigated in seminal plasma samples from only a small number of NOA patients. In future investigations, a larger sample size should be adopted and the functional role of the three sp-miRNAs should be further characterized in animal models.

WIDER IMPLICATIONS OF THE FINDINGS

Given that sp-miRNAs show reproducible and stable expression levels, they are potentially novel noninvasive biomarkers for the diagnosis of NOA. We propose that the three sp-miRNAs described above may participate in a methylation-miRNA-gene network related to NOA development. This work provides a foundation for interpretation of miRNA changes associated with pathogenesis of NOA and extends the current understanding of human NOA pathogenesis.

microRNA-200c modulates the epithelial-to-mesenchymal transition in human renal cell carcinoma metastasis

microRNAs (miRNAs) play essential roles in several physiological and pathological processes, including tumor metastasis. Metastasis is associated with poor prognosis in renal carcinoma patients and almost 20-30% of patients present with distant metastasis at the time of diagnosis. The aim of the present study was to investigate the possible roles of miR-200c in regulating metastasis and to identify its target genes in renal cell carcinoma (RCC). Among the miRNAs downregulated in our tissue specimen microarray, miR-200c was downregulated significantly. Functional assays demonstrated that restoration of miR-200c significantly inhibited the migration and invasion of SN12-PM6 and 786-0 cells in vitro. Genome-wide gene expression analysis and TargetScan database studies showed that ZEB1, which has been shown to promote tumor invasion and migration through E-cadherin gene silencing, is a promising candidate target gene of miR‑200c. Overexpression of miR-200c in SN12-PM6 and 786-0 cells was concurrent with downregulation of ZEB1 and upregulation of E-cadherin mRNA and protein. In addition, miR-200c affected the protein expression of p-Akt and Akt. Thus, our study demonstrated that miR-200c decreases the metastatic ability of renal carcinoma cells by upregulating E-cadherin through ZEB1 and that modulating the expression of miR-200c could influence Akt protein levels. We therefore concluded that there is an Akt-miR-200c-E-cadherin axis in the epithelial-to-mesenchymal transition process in RCC.

miR-192, miR-194 and miR-215: a convergent microRNA network suppressing tumor progression in renal cell carcinoma

MicroRNAs (miRNAs) play a crucial role in tumor progression and metastasis. We, and others, recently identified a number of miRNAs that are dysregulated in metastatic renal cell carcinoma compared with primary renal cell carcinoma. Here, we investigated three miRNAs that are significantly downregulated in metastatic tumors: miR-192, miR-194 and miR-215. Gain-of-function analyses showed that restoration of their expression decreases cell migration and invasion in renal cell carcinoma cell line models, whereas knockdown of these miRNAs resulted in enhancing cellular migration and invasion abilities. We identified three targets of these miRNAs with potential role in tumor aggressiveness: murine double minute 2, thymidylate synthase, and Smad Interacting protein 1/zinc finger E-box binding homeobox 2. We observed a convergent effect (the same molecule can be targeted by all three miRNAs) and a divergent effect (the same miRNA can control multiple targets) for these miRNAs. We experimentally validated these miRNA-target interactions using three independent approaches. First, we observed that miRNA overexpression significantly reduces the mRNA and protein levels of their targets. In the second, we observed significant reduction of the luciferase signal of a vector containing the 3'UTR of the target upon miRNA overexpression. Finally, we show the presence of inverse correlation between miRNA changes and the expression levels of their targets in patient specimens. We also examined the prognostic significance of miR-215 in renal cell carcinoma. Lower expression of miR-215 is associated with significantly reduced disease-free survival time. These findings were validated on an independent data set from The Cancer Genome Atlas. These results can pave the way to the clinical use of miRNAs as prognostic markers and therapeutic targets.

Tumor suppressive miR-509-5p contributes to cell migration, proliferation and antiapoptosis in renal cell carcinoma

PURPOSE

The aim of this study was to determine the expression and function of miR-509-5p in renal cell carcinoma (RCC).

MATERIALS AND METHODS

In this research, we have conducted quantitative real-time polymerase chain reaction (qRT-PCR) assay to determine the expression level of miR-509-5p in tissues and plasma from renal cell carcinoma patients. We preformed in vitro migration scratch assay, flow cytometry analysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to determine the exact function of miR-509-5p.

RESULTS

We evaluated the expression level of miR-509-5p in RCC tissues and paired adjacent normal tissues from 42 patients and found that miR-509-5p expression in 42 RCC specimens was significantly down-regulated compared to that in adjacent normal tissue. Furthermore, the level of miR-509-5p in RCC patients' plasma was significantly lower than that in control plasma. In addition, the overexpression of miR-509-5p suppressed the proliferation of RCC cell (786-0), induced cell apoptosis and inhibited cell migration in vitro.

CONCLUSION

In this study, we have shown that miR-509-5p played an important role in RCC by inhibiting cell proliferation and migration and by promoting cell apoptosis. In addition, miR-509-5p expression was significantly lower in RCC patient plasma compared to that in normal individuals.

δ-Opioid receptor activation modified microRNA expression in the rat kidney under prolonged hypoxia

Hypoxic/ischemic injury to kidney is a frequently encountered clinical problem with limited therapeutic options. Since microRNAs are differentially involved in hypoxic/ischemic events and δ-opioid receptor (DOR) activation is known to protect against hypoxic/ischemic injury, we speculated on the involvement of DOR activation in altering the microRNA (miRNA) expression in kidney under hypoxic condition. We selected 31 miRNAs based on microarray data for quantitative PCR analysis. Among them, 14 miRNAs were significantly altered after prolonged hypoxia, DOR activation or a combination of both. We found that 1) DOR activation alters miRNA expression profiles in normoxic conditions; 2) hypoxia differentially alters miRNA expression depending on the duration of hypoxia; and 3) DOR activation can modify hypoxia-induced changes in miRNA expression. For example, 10-day hypoxia reduced the level of miR-212 by over 70%, while DOR activation could mimic such reduction even in normoxic kidney. In contrast, the same stress increased miR-29a by >100%, which was reversed following DOR activation. These first data suggest that hypoxia comprehensively modifies the miRNA profile within the kidney, which can be mimicked or modified by DOR activation. Ascertaining the targeted pathways that regulate the diverse cellular and molecular functions of miRNA may provide new insights into potential therapies for hypoxic/ischemic injury of the kidney.

Development and validation of a microRNA-based diagnostic assay for classification of renal cell carcinomas

Renal cancers account for more than 3% of adult malignancies and cause more than 13,000 deaths per year in the US alone. The four most common types of kidney tumors include the malignant renal cell carcinomas; clear cell, papillary, chromophobe and the benign oncocytoma. These histological subtypes vary in their clinical course and prognosis, and different clinical strategies have been developed for their management. In some kidney tumor cases it can be very difficult for the pathologist to distinguish between tumor types on the basis of morphology and immunohistochemistry (IHC). In this publication we present the development and validation of a microRNA-based assay for classifying primary kidney tumors. The assay, which classifies the four main kidney tumor types, was developed based on the expression of a set of 24 microRNAs. A validation set of 201 independent samples was classified using the assay and analyzed blindly. The assay produced results for 92% of the samples with an accuracy of 95%.

δ-opioid receptor activation and microRNA expression of the rat cortex in hypoxia

Prolonged hypoxic/ischemic stress may cause cortical injury and clinically manifest as a neurological disability. Activation of the δ-opioid receptor (DOR) may induce cortical protection against hypoxic/ischemic insults. However, the mechanisms underlying DOR protection are not clearly understood. We have recently found that DOR activation modulates the expression of microRNAs (miRNAs) in the kidney exposed to hypoxia, suggesting that DOR protection may involve a miRNA mechanism. To determine if the miRNAs expressed in the cortex mediated DOR neuroprotection, we examined 19 miRNAs that were previously identified as hypoxia- and DOR-regulated miRNAs in the kidney, in the rat cortex treated with UFP-512, a potent and specific DOR agonist under hypoxic condition. Of the 19 miRNAs tested, 17 were significantly altered by hypoxia and/or DOR activation with the direction and amplitude varying depending on hypoxic duration and times of DOR treatment. Expression of several miRNAs such as miR-29b, -101b, -298, 324-3p, -347 and 466b was significantly depressed after 24 hours of hypoxia. Similar changes were seen in normoxic condition 24 hours after DOR activation with one-time treatment of UFP-512. In contrast, some miRNAs were more tolerant to hypoxic stress and showed significant reduction only with 5-day (e.g., miR-31 and -186) or 10-day (e.g., miR-29a, let-7f and -511) exposures. In addition, these miRNAs had differential responses to DOR activation. Other miRNAs like miRs-363* and -370 responded only to the combined exposure to hypoxia and DOR treatment, with a notable reduction of >70% in the 5-day group. These data suggest that cortical miRNAs are highly yet differentially sensitive to hypoxia. DOR activation can modify, enhance or resolve the changes in miRNAs that target HIF, ion transport, axonal guidance, free radical signaling, apoptosis and many other functions.

MicroRNAs in kidney disease: an emerging understanding

MicroRNAs (miRNAs) are short noncoding RNA molecules that function by negatively regulating the expression of their target genes in a tightly controlled manner. Accumulating evidence, based in part on effects seen after miRNA overexpression and/or knockdown, points to the critical involvement of miRNAs in kidney function in health and disease. In this review, we provide a quick overview of the biogenesis of miRNAs and their potential involvement in kidney development and normal function. We also discuss the current literature that has begun to uncover the role of miRNAs in the pathogenesis of kidney diseases, including diabetic nephropathy, hypertension, glomerulonephritis, and cancer. As such, miRNAs have potential utility in the clinical realm as disease biomarkers. Moreover, miRNAs represent an attractive therapeutic target for a number of kidney diseases. We close by discussing a number of potential challenges that face the field of miRNA research and clinical use.

MicroRNA-99a induces G1-phase cell cycle arrest and suppresses tumorigenicity in renal cell carcinoma

Background

A growing body of evidence suggests that microRNAs (miRNAs) play an important role in cancer diagnosis and therapy. MicroRNA-99a (miR-99a), a potential tumor suppressor, is downregulated in several human malignancies. The expression and function of miR-99a, however, have not been investigated in human renal cell carcinoma (RCC) so far. We therefore examined the expression of miR-99a in RCC cell lines and tissues, and assessed the impact of miR-99a on the tumorigenesis of RCC.

Methods

MiR-99a levels in 40 pairs of RCC and matched adjacent non-tumor tissues were assessed by real-time quantitative Reverse Transcription PCR (qRT-PCR). The RCC cell lines 786-O and OS-RC-2 were transfected with miR-99a mimics to restore the expression of miR-99a. The effects of miR-99a were then assessed by cell proliferation, cell cycle, transwell, and colony formation assay. A murine xenograft model of RCC was used to confirm the effect of miR-99a on tumorigenicity in vivo. Potential target genes were identified by western blotting and luciferase reporter assay.

Results

We found that miR-99a was remarkably downregulated in RCC and low expression level of miR-99a was correlated with poor survival of RCC patients. Restoration of miR-99a dramatically suppressed RCC cells growth, clonability, migration and invasion as well as induced G1-phase cell cycle arrest in vitro. Moreover, intratumoral delivery of miR-99a could inhibit tumor growth in murine xenograft models of human RCC. In addition, we also fond that mammalian target of rapamycin (mTOR) was a direct target of miR-99a in RCC cells. Furthermore, siRNA-mediated knockdown of mTOR partially phenocopied the effect of miR-99a overexpression, suggesting that the tumor suppressive role of miR-99a may be mediated primarily through mTOR regulation.

Conclusions

Collectively, these results demonstrate for the first time, to our knowledge, that deregulation of miR-99a is involved in the etiology of RCC partially via direct targeting mTOR pathway, which suggests that miR-99a may offer an attractive new target for diagnostic and therapeutic intervention in RCC.

MiR-210 expression in tumor tissue and in vitro effects of its silencing in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common neoplasm of adult kidney accounting for about 3 % of adult malignancies. MicroRNAs (miRNAs) are a class of naturally occurring, short non-coding RNAs that regulate gene expression at the post-transcriptional level. We determined global miRNA expression profiles of RCC and parallel renal parenchyma tissues by using quantitative reverse transcriptase-polymerase chain reaction-based TaqMan low-density arrays. Afterward, we validated the difference in miR-210 expression levels on the larger group of RCC patients (35 RCC versus 10 non-tumorous parenchyma samples). Functional in vitro experiments were performed on ACHN and CAKI-2 RCC cell lines transfected with miRNA-210 inhibitor. Cell viability, apoptosis, cell cycle, scratch wound migration assay, and invasion assay (xCELLigence) were performed. We have identified original ccRCC-specific miRNA signature in clinical samples (73 miRNAs were significantly downregulated and five miRNAs upregulated (P < 0.003)). Increased expression levels of miR-210 in RCC tumor tissue were independently validated. We observed decreased viability of ACHN and CAKI-2 cells and accumulation of CAKI-2 in G2 phase of cell cycle after silencing of miR-210 expression. Downregulation of miR-210 also reduced the migratory and invasive potential of ACHN metastatic RCC cells. Moreover, we showed downregulation of HIF1a protein in both cell lines after miR-210 silencing indicating participation of miR-210 in hypoxic processes of RCC not only through regulation of its target mRNAs but also by indirect regulation of HIF1a. To our knowledge, this is the first report to show miR-210 regulatory effects on cell migration, invasive potential, and HIF1a protein in RCC cells.

The miRNA-kallikrein axis of interaction: a new dimension in the pathogenesis of prostate cancer

Kallikrein-related peptidases (KLKs) are a family of serine proteases that were shown to be useful cancer biomarkers. KLKs have been shown to be dysregulated in prostate cancer (PCa). microRNAs (miRNAs) are short RNA nucleotides that negatively regulate gene expression and have been reportedly dysregulated in PCa. We compiled a comprehensive list of 55 miRNAs that are differentially expressed in PCa from previous microarray analysis and published literature. Target prediction analyses showed that 29 of these miRNAs are predicted to target 10 KLKs. Eight of these miRNAs were predicted to target more than one KLK. Quantitative real-time (qRT)-PCR demonstrated that there was an inverse correlation pattern in the expression (normal vs. cancer) between dysregulated miRNAs and their target KLKs. In addition, we experientially validated the miRNA-KLK interaction by transfecting miR-331-3p and miR-143 into a PCa cell line. Decreased expression of targets KLK4 and KLK10, respectively, and decreased cellular growth were observed. In addition to KLKs, dysregulated miRNAs were predicted to target other genes involved in the pathogenesis of PCa. These data show that miRNAs can contribute to KLK regulation in PCa. The miRNA-KLK axis of interaction projects a new element in the pathogenesis of PCa that may have therapeutic implications.

Stability of membranous nanostructures: a possible key mechanism in cancer progression

Membranous nanostructures, such as nanovesicles and nanotubules, are an important pool of biological membranes. Recent results indicate that they constitute cell-cell communication systems and that cancer development is influenced by these systems. Nanovesicles that are pinched off from cancer cells can move within the circulation and interact with distant cells. It has been suggested and indicated by experimental evidence that nanovesicles can induce metastases from the primary tumor in this way. Therefore, it is of importance to understand better the mechanisms of membrane budding and vesiculation. Here, a theoretical description is presented concerning consistently related lateral membrane composition, orientational ordering of membrane constituents, and a stable shape of nanovesicles and nanotubules. It is shown that the character of stable nanostructures reflects the composition of the membrane and the intrinsic shape of its constituents. An extension of the fluid mosaic model of biological membranes is suggested by taking into account curvature-mediated orientational ordering of the membrane constituents on strongly anisotropically curved regions. Based on experimental data for artificial membranes, a possible antimetastatic effect of plasma constituents via mediation of attractive interaction between membranous structures is suggested. This mediated attractive interaction hypothetically suppresses nanovesiculation by causing adhesion of buds to the mother membrane and preventing them from being pinched off from the membrane.

The clinical utility of miR-21 as a diagnostic and prognostic marker for renal cell carcinoma

Renal cell carcinoma (RCC) is the most common neoplasm of the kidney. Increasing evidence suggests that microRNAs are dysregulated in RCC and are important factors in RCC pathogenesis. miR-21 is a known oncogene with tumor-promoting effects in many types of cancer. In this study, we analyzed miR-21 in 121 cases of healthy kidney and different RCC subtypes, including clear cell (ccRCC), papillary (pRCC), chromophobe (chRCC), and oncocytoma. Total RNA was extracted, and the expression of miR-21 was measured with real-time quantitative RT-PCR using miR-21-specific probes. The expression of miR-21 was significantly up-regulated in RCC compared with healthy kidney. There was a significant difference in the expression levels between RCC subtypes, with the highest levels of expression in ccRCC and pRCC subtypes. miR-21 expression distinguished ccRCC and pRCC from chRCC and oncocytoma with 90% specificity (95% CI, 63.9% to 98.1%) and 83% sensitivity (95% CI, 53.5% to 97.6%). Significantly higher miR-21 levels were associated with higher stage and grade. Patients who were miR-21 positive had statistically significant shorter disease-free and overall survival rates. Thus, miR-21 is up-regulated in RCC, and its expression levels can be used as a diagnostic marker to distinguish ccRCC and pRCC from chRCC and oncocytoma. Moreover, it has potential as a prognostic marker in RCC, although it is not independent of tumor stage and grade.

Pleiotropic action of renal cell carcinoma-dysregulated miRNAs on hypoxia-related signaling pathways

The von Hippel-Lindau (VHL) gene is lost in ≈ 70% of all renal cell carcinomas (RCCs); however, increasing evidence supports the involvement of alternative mechanisms in the regulation of VHL expression, including suppression by microRNAs (miRNAs). miRNAs are small, noncoding RNA molecules that regulate gene expression through binding to target mRNAs. In this study, we found that miRNAs, which are dysregulated in cases of RCC, can target multiple members of RCC-related signaling pathways. Importantly, both VHL and the hypoxia-inducible factor 1-α gene are experimentally validated and are likely direct targets of miR-17-5p and miR-224, as shown by both luciferase assay and Western blot analysis. We found a negative correlation between miR-17-5p and its two predicted targets, VEGF-A and EGLN3, and between miR-224 and its targets SMAD4 and SMAD5 in RCC specimens, suggesting that downstream signaling pathways are also modulated by clear cell RCC-dysregulated miRs. Results from our bioinformatics analysis show that a single miRNA molecule can target multiple components of the same pathway and that multiple miRNAs can target the same molecule. Our results also indicate that miRNAs represent a mechanism for the inactivation of VHL in cases of RCC and can elucidate a new dimension in cancer pathogenesis. As such, miRNAs exemplify new potential therapeutic targets with a significant effect on both tumor growth and metastatic potential.

Role of microRNAs in kidney homeostasis and disease

MicroRNAs (miRNAs) are endogenous short (20-22 nucleotides) non-coding RNA molecules that mediate gene expression. This is an important regulatory mechanism to modulate fundamental cellular processes such as differentiation, proliferation, death, metabolism, and pathophysiology of many diseases. The miRNA expression profile of the kidney differs greatly from that of other organs, as well as between the different regions in the kidney. In kidneys, miRNAs are indispensable for development and homeostasis. In this review, we explore the involvement of miRNAs in the regulation of blood pressure, hormone, water, and ion balance pertaining to kidney homeostasis. We also highlight their importance in renal pathophysiology, such as in polycystic disease, diabetic nephropathy, nephrogenic diabetes insipidus, hypertension, renal cancer, and kidney fibrosis (epithelial-mesenchymal transition). In addition, we highlight the need for further investigations on miRNA-based studies in the development of diagnostic, prognostic, and therapeutic tools for renal diseases.

MicroRNAs are dynamically regulated and play an important role in LPS-induced lung injury

Acute lung injury is characterized by an increase of inflammatory reaction and severe lung edema. Even if there have been great advances in the identification of genes and signaling pathways involved in acute lung injury, the fundamental mechanisms of initiation and propagation of acute lung injury have not been understood completely. A growing amount of evidence indicates that microRNAs (miRNAs) are involved in various human diseases. However, the expression profile and function of miRNAs in acute lung injury have not been investigated. Here, using real-time polymerase chain reaction analysis, we show that a collection of miRNAs is dynamically regulated in lipopolysaccharide (LPS)-induced mouse acute lung injury. Among them, miR-199a and miR-16 are the most significantly down-regulated miRNAs. To study the role of miR-199a and miR-16 in acute lung injury, an over-expression of miR-199a or miR-16 assay was performed in LPS-treated A549 cells, and then the expression of inflammatory factors was analyzed. Over-expression of miR-199a could not alter the expression level of interleukin (IL)-6 and tumor necrosis factor-alpha (TNFα), while up-regulation of miR-16 could significantly down-regulate IL-6 and TNFα expression level. Using bioinformatic analysis, we show that a 3' untranslational region (UTR) of IL-6 and TNFα contains the binding sites of miR-16. Accordingly, over-expression of miR-16 could significantly suppress the luciferase activity of reporter fusion with the binding sites of TNFα in its 3'UTR region, suggesting that miR-16 played its role in LPS-induced lung inflammation by a direct manner. In this study, we show for the first time that miRNAs are dynamically regulated and play an important function in LPS-induced lung injury.

miRNA profiling in metastatic renal cell carcinoma reveals a tumour-suppressor effect for miR-215

Background:

Renal cell carcinoma (RCC) is the most common neoplasm of the adult kidney. Metastatic RCC is difficult to treat. The 5-year survival rate for metastatic RCC is ⩽10%. Recently, microRNAs (miRNAs) have been shown to have a role in cancer metastasis and potential as prognostic biomarkers in cancer.

Method:

We performed a miRNA microarray to identify a miRNA signature characteristic of metastatic compared with primary RCCs. We validated our results by quantitative real-time PCR. We performed experimental and bioinformatic analyses to explore the involvement of miR-215 in RCC progression and metastasis.

Results:

We identified 65 miRNAs that were significantly altered in metastatic compared with primary RCCs. We validated our results by examining the expression of miR-10b, miR-126, miR-196a, miR-204 and miR-215, in two independent cohorts of patients. We showed that overexpression of miR-215 decreased cellular migration and invasion in an RCC cell line model. In addition, through gene expression profiling, we identified direct and indirect targets of miR-215 that can contribute to tumour metastasis.

Conclusion:

Our analysis showed that miRNAs are altered in metastatic RCCs and can contribute to kidney cancer metastasis through different biological processes. Dysregulated miRNAs represent potential prognostic biomarkers and may have therapeutic applications in kidney cancer.

MicroRNAs as regulators of signal transduction in urological tumors

BACKGROUND

MicroRNAs (miRNAs) are short noncoding RNAs that have been shown to play pivotal roles in carcinogenesis. In the past decade, miRNAs have been the focus of much research in oncology, and there are great expectations for their utility as cancer biomarkers and therapeutic targets.

CONTENT

In this review we examine how miRNAs can regulate signal transduction pathways in urological tumors. We performed in silico target prediction using TargetScan 5.1 to identify the signal transduction targets of miRNA, and we summarize the experimental evidence detailing miRNA regulation of pathways analyzed herein.

SUMMARY

miRNAs, which have been shown to be dysregulated in bladder, prostate, and renal cell cancer, are predicted to target key proteins in signal transduction. Because androgen receptor signaling is a major regulator of prostate cancer growth, its regulation by miRNAs has been well described. In addition, members of the phosphatidylinositol 3-kinase/Akt (RAC-alpha serine/threonine-protein kinase) signaling pathway have been shown to be susceptible to miRNA regulation. In contrast, there are very few studies on the impact of miRNA regulation on signaling by VHL (von Hippel-Lindau tumor suppressor) and vascular endothelial growth factor in renal cell carcinoma or by fibroblast growth factor receptor 3 and p53 in bladder cancer. Many miRNAs are predicted to target important signaling pathways in urological tumors and are dysregulated in their respective cancer types; a systematic overview of miRNA regulation of signal transduction in urological tumors is pending. The identification of these regulatory networks might lead to novel targeted cancer therapies. In general, the targeting of miRNAs is a valuable approach to cancer therapy, as has been shown recently for various types of cancer.