MicroRNAs in carcinogenesis

Identification of Let-7 miRNA Activity as a Prognostic Biomarker of SHH Medulloblastoma

Medulloblastoma (MB) is the most common pediatric embryonal brain tumor. The current consensus classifies MB into four molecular subgroups: sonic hedgehog-activated (SHH), wingless-activated (WNT), Group 3, and Group 4. MYCN and let-7 play a critical role in MB. Thus, we inferred the activity of miRNAs in MB by using the ActMiR procedure. SHH-MB has higher MYCN expression than the other subgroups. We showed that high MYCN expression with high let-7 activity is significantly associated with worse overall survival, and this association was validated in an independent MB dataset. Altogether, our results suggest that let-7 activity and MYCN can further categorize heterogeneous SHH tumors into more and less-favorable prognostic subtypes, which provide critical information for personalizing treatment options for SHH-MB. Comparing the expression differences between the two SHH-MB prognostic subtypes with compound perturbation profiles, we identified FGFR inhibitors as one potential treatment option for SHH-MB patients with the less-favorable prognostic subtype.

miR-539 activates the SAPK/JNK signaling pathway to promote ferropotosis in colorectal cancer by directly targeting TIPE

Colorectal cancer (CRC) is a common tumor that harms human health with a high recurrence rate. It has been reported that the expression of microRNA-539 (miR-539) is low in several types of cancer, including CRC. Tumor necrosis factor (TNF)-α-induced protein 8 (TNFAIP8/TIPE) is highly expressed in CRC and promotes the proliferation, migration and angiogenesis of CRC. However, the relationship between miR-539 and TIPE and the mechanisms by which they regulate the proliferation of CRC remain to be explored. We aimed to investigate the functions and mechanisms of miR-539 in CRC proliferation. Functionally, miR-539 can bind to and regulate the expression of TIPE, and miR-539 activates SAPK/JNK to downregulate the expression of glutathione peroxidase 4 (GPX4) and promote ferroptosis. Our data reveal the novel role of miR-539 in regulating ferroptosis in CRC via activation of the SAPK/JNK axis, providing new insight into the mechanism of abnormal proliferation in CRC and a novel potential therapeutic target for advanced CRC.

MicroRNA-125a-5p modulates the proliferation and apoptosis of TM4 Sertoli cells by targeting RAB3D and regulating the PI3K/AKT signaling pathway

Sertoli cells are cells that provide protection and nutrition for developing sperm. Each stage of sperm development occurs on the surface of Sertoli cells. MicroRNA (MiR)-125a-5p is involved in male reproduction. The current research aimed to probe the role of miR-125a-5p in Sertoli cell function. Functionally, miR-125a-5p knockdown facilitated Sertoli cell proliferation, while miR-125a-5p overexpression suppressed Sertoli cell proliferation, as evidenced by 5-ethynyl-20-deoxyuridine incorporation assay. Additionally, miR-125a-5p knockdown inhibited Sertoli cell apoptosis, while miR-125a-5p upregulation facilitated Sertoli cell apoptosis, as evidenced by flow cytometry analysis. Computationally, we identified four predicted mRNA targets of miR-125a-5p. Based on the results of luciferase reporter assay, miR-125a-5p was confirmed to bind to the predicted sequence in the Ras-related protein Rab-3D (RAB3D) 3'UTR. Rescue experiments showed that miR-125a-5p suppressed the proliferative ability of TM4 Sertoli cells and facilitated their apoptosis by targeting RAB3D. Finally, our data confirmed that miR-125a-5p and RAB3D modulated activation of the PI3K/AKT pathway. In conclusion, our data showed that miR-125a-5p regulated Sertoli cell proliferation and apoptosis by targeting RAB3D and regulating the PI3K/AKT pathway.

Single-Molecule FRET-Based Dynamic DNA Sensor

Selective and sensitive detection of nucleic acid biomarkers is of great significance in early-stage diagnosis and targeted therapy. Therefore, the development of diagnostic methods capable of detecting diseases at the molecular level in biological fluids is vital to the emerging revolution in the early diagnosis of diseases. However, the vast majority of the currently available ultrasensitive detection strategies involve either target/signal amplification or involve complex designs. Here, using a p53 tumor suppressor gene whose mutation has been implicated in more than 50% of human cancers, we show a background-free ultrasensitive detection of this gene on a simple platform. The sensor exhibits a relatively static mid-FRET state in the absence of a target that can be attributed to the time-averaged fluorescence intensity of fast transitions among multiple states, but it undergoes continuous dynamic switching between a low- and a high-FRET state in the presence of a target, allowing a high-confidence detection. In addition to its simple design, the sensor has a detection limit down to low femtomolar (fM) concentration without the need for target amplification. We also show that this sensor is highly effective in discriminating against single-nucleotide polymorphisms (SNPs). Given the generic hybridization-based detection platform, the sensing strategy developed here can be used to detect a wide range of nucleic acid sequences enabling early diagnosis of diseases and screening genetic disorders.

Expression of miR-34a is a sensitive biomarker for exposure to genotoxic agents in human lymphoblastoid TK6 cells

miR-34a has been identified as a tumor suppressor microRNA (miRNA) involved in the P53 network. Its expression levels correlate to carcinogenesis, which are generally lower in tumor tissue and higher in response to DNA damage. In this study, the response of miR-34a from exposure to genotoxic agents in human lymphoblastoid TK6 cells was evaluated to assess whether the expression of this miRNA could be used as an early indicator for genotoxic damage in mammalian cells. TK6 cells were treated with seven genotoxic agents with different mode-of-actions (cisplatin, N-ethyl-N-nitrosourea, etoposide, mitomycin C, methyl methanesulphonate, taxol, and X-ray radiation) and a non-genetic toxin (usnic acid) at different concentrations for four hours (except for X-rays) and the expression levels of miR-34a were measured 24 h after the beginning of the treatments. The expression levels of miR-34a were significantly increased by these genetic toxins in a dose-dependent manner, while no significant change in miRNA expression was found in the usnic acid-treated cells. These results suggest that miR-34a can respond to genotoxic insults sensitively; thus, miR-34a expression has the potential to be used to evaluate genotoxicity of agents.

miR-502-5p inhibits the proliferation, migration and invasion of gastric cancer cells by targeting SP1

Gastric cancer (GC) is the third most common cause of cancer-associated mortality in China. Aberrant microRNA (miR) expression can occur through multiple biological processes and has been implicated in cancer development. However, to the best of our knowledge, the function of miR-502-5p in GC is currently unclear. In the present study, the expression and function of miR-502-5p in GC was evaluated. Reverse transcription-quantitative (RT-q) PCR was used to measure the expression levels of miR-502-5p in GC tissues, normal adjacent tissues, a normal human gastric epithelial cell line (GES-1) and two GC cell lines. miR-502-5p expression levels were significantly lower in GC tissues and GC cell lines compared with those in adjacent normal tissues and GES-1 cells, respectively. Subsequently, the target genes of miR-502-5p were predicted, and it was demonstrated that the transcription factor SP1 was a direct target. SP1 expression, cell viability, migration and invasion, and SP1 protein levels were examined using RT-qPCR, an MTT assay, Transwell assay and western blotting, respectively. Human GC cells were then transfected with an miR-502-5p mimic to emulate miR-502-5p overexpression, resulting in inhibition of the proliferation, migration and invasion capacities of human GC cells. Compared with the negative control, cells overexpressing miR-502-5p had decreased levels of SP1 mRNA and protein. These data suggest that miR-502-5p serves as a tumor suppressor gene by targeting SP1 to regulate the proliferation, migration and invasion of GC cells.

Expression profiles of miRNAs in giant cell tumor of bone showed miR-187-5p and miR-1323 can regulate biological functions through inhibiting FRS2

Background

Giant cell tumor of bone (GCTB) is considered to be a kind of borderline tumor, which has a tendency to recur and translocate. MicroRNAs are one type of small noncoding RNA, which can inhibit the translation of targeted mRNA through RNA‐induced silencing complex.

Methods

Microarray was conducted on three groups of tumor tissues and normal tissues from patients with GCTB, and results showed different expression profiles of miRNAs with Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes analysis. The functions of miR‐187‐5p and miR‐1323, which were highly expressed in GCTB, were examined by 5‐ethynyl‐2′‐deoxyuridine (EDU), transwell, and CCK8 assays. RNAhybrid et al. (rna prediction softwares) predicted that the two microRNAs targeted fibroblast growth factor receptor substrate 2 (FRS2), which was verified by luciferase assay and rescue experiments.

Results

miR‐187‐5p and miR‐1323 were highly expressed in tumor tissues. They can jointly regulate the biological functions of GCTB in vitro. Luciferase assay confirmed that the two microRNAs can bind to the 3′ untranslated regions (UTR) of mRNA of FRS2. And, rescue experiments verified the relationships between the two microRNAs and FRS2.

Conclusion

There were some different‐expressed microRNAs between GCTB and normal tissues. miR‐187‐5p and miR‐1323 can regulate the biological functions of GCTB through influencing the expression of FRS2.

LncRNA H19-elevated LIN28B promotes lung cancer progression through sequestering miR-196b

LncRNA H19 is involved in the development of multiple cancers. Here, we firstly provide new evidence that H19 can induce LIN28B, a conserved RNA binding protein, to accelerate lung cancer growth through sponging miR-196b. Abundance in LIN28B was observed in clinical lung cancer samples. A positive link was observed between H19 and LIN28B in clinical lung cancer samples. In lung cancer cells, H19 was capable of increasing LIN28B expression. Mechanistically, miR-196b directly targeted LIN28B to inhibit LIN28B expression. H19 was capable of promoting LIN28B expression through sequestering miR-196b. Functionally, H19-increased LIN28B conferred the cell proliferation of lung cancer. Our finding indicates that H19 depresses miR-196b to elevate LIN28B, resulting in accelerating cell proliferation in lung cancer.

3' RNA Uridylation in Epitranscriptomics, Gene Regulation, and Disease

Emerging evidence implicates a wide range of post-transcriptional RNA modifications that play crucial roles in fundamental biological processes including regulating gene expression. Collectively, they are known as epitranscriptomics. Recent studies implicate 3' RNA uridylation, the non-templated addition of uridine(s) to the terminal end of RNA, as a key player in epitranscriptomics. In this review, we describe the functional roles and significance of 3' terminal RNA uridylation that has diverse functions in regulating both mRNAs and non-coding RNAs. In mammals, three Terminal Uridylyl Transferases (TUTases) are primarily responsible for 3' RNA uridylation. These enzymes are also referred to as polyU polymerases. TUTase 1 (TUT1) is implicated in U6 snRNA maturation via uridylation. The TUTases TUT4 and/or TUT7 are the predominant mediators of all other cellular uridylation. Terminal uridylation promotes turnover for many polyadenylated mRNAs, replication-dependent histone mRNAs that lack polyA-tails, and aberrant structured noncoding RNAs. In addition, uridylation regulates biogenesis of a subset of microRNAs and generates isomiRs, sequent variant microRNAs that have altered function in specific cases. For example, the RNA binding protein and proto-oncogene LIN28A and TUT4 work together to polyuridylate pre-let-7, thereby blocking biogenesis and function of the tumor suppressor let-7 microRNA family. In contrast, monouridylation of Group II pre-miRNAs creates an optimal 3' overhang that promotes recognition and subsequent cleavage by the Dicer-TRBP complex that then yields the mature microRNA. Also, uridylation may play a role in non-canonical microRNA biogenesis. The overall significance of 3' RNA uridylation is discussed with an emphasis on mammalian development, gene regulation, and disease, including cancer and Perlman syndrome. We also introduce recent changes to the HUGO-approved gene names for multiple terminal nucleotidyl transferases that affects in part TUTase nomenclature (TUT1/TENT1, TENT2/PAPD4/GLD2, TUT4/ZCCHC11/TENT3A, TUT7/ZCCHC6/TENT3B, TENT4A/PAPD7, TENT4B/PAPD5, TENT5A/FAM46A, TENT5B/FAM46B, TENT5C/FAM46C, TENT5D/FAM46D, MTPAP/TENT6/PAPD1).

MicroRNA-216b reduces growth, migration and invasion of pancreatic ductal adenocarcinoma cells by directly targeting ρ-associated coiled-coil containing protein kinase 1

Developments in cancer therapy have greatly improved the survival time for patients with pancreatic ductal adenocarcinoma (PDAC); however, the prognosis of patients with PDAC remains poor. Understanding the expression patterns and functions of microRNAs may provide strategies for the diagnosis and treatment of patients with PDAC. The present study aimed to explore the expression and functions of microRNA-216b (miR-216b) in PDAC. The expression of miR-216b in PDAC tissues and cell lines was quantified with reverse transcription-quantitative polymerase chain reaction. An miR-216b mimic was introduced into PDAC cells to induce the effects of miR-21b overexpression. The effects of miR-216b overexpression on growth, migration and invasion of PDAC cells were evaluated by cell proliferation assay, migration and invasion assays, respectively. The molecular mechanism underlying the suppressive effects of miR-216b on PDAC was also examined; a direct target gene of miR-216b, ρ-associated coiled-coil containing protein kinase 1 (ROCK1), was downregulated by ROCK1 short interfering RNA to investigate the effects on growth, migration and invasion of PDAC cells. The present study revealed that miR-216b was significantly downregulated in PDAC tissues and cell lines. Overexpression of miR-216b inhibited growth, migration and invasion of PDAC cells in vitro. ROCK1 was identified as a direct target gene of miR-216b in pancreatic cancer and the downregulation of ROCK1 resembled the effects of miR-216b overexpression in PDAC cells. Taken together, miR-216b acted as a tumor suppressor in PDAC and may represent a novel therapeutic target in PDAC.

The LIN28/let-7 Pathway in Cancer

Among all tumor suppressor microRNAs, reduced let-7 expression occurs most frequently in cancer and typically correlates with poor prognosis. Activation of either LIN28A or LIN28B, two highly related RNA binding proteins (RBPs) and proto-oncogenes, is responsible for the global post-transcriptional downregulation of the let-7 microRNA family observed in many cancers. Specifically, LIN28A binds the terminal loop of precursor let-7 and recruits the Terminal Uridylyl Transferase (TUTase) ZCCHC11 that polyuridylates pre-let-7, thereby blocking microRNA biogenesis and tumor suppressor function. For LIN28B, the precise mechanism responsible for let-7 inhibition remains controversial. Functionally, the decrease in let-7 microRNAs leads to overexpression of their oncogenic targets such as MYC, RAS, HMGA2, BLIMP1, among others. Furthermore, mouse models demonstrate that ectopic LIN28 expression is sufficient to drive and/or accelerate tumorigenesis via a let-7 dependent mechanism. In this review, the LIN28/let-7 pathway is discussed, emphasizing its role in tumorigenesis, cancer stem cell biology, metabolomics, metastasis, and resistance to ionizing radiation and several chemotherapies. Also, emerging evidence will be presented suggesting that molecular targeting of this pathway may provide therapeutic benefit in cancer.

Reassessment of MTBE cancer potency considering modes of action for MTBE and its metabolites

A 1999 California state agency cancer potency (CP) evaluation of methyl tert-butyl ether (MTBE) assumed linear risk extrapolations from tumor data were plausible because of limited evidence that MTBE or its metabolites could damage DNA, and based such extrapolations on data from rat gavage and rat and mouse inhalation studies indicating elevated tumor rates in male rat kidney, male rat Leydig interstitial cells, and female rat leukemia/lymphomas. More recent data bearing on MTBE cancer potency include a rodent cancer bioassay of MTBE in drinking water; several new studies of MTBE genotoxicity; several similar evaluations of MTBE metabolites, formaldehyde, and tert-butyl alcohol or TBA; and updated evaluations of carcinogenic mode(s) of action (MOAs) of MTBE and MTBE metabolite's. The lymphoma/leukemia data used in the California assessment were recently declared unreliable by the U.S. Environmental Protection Agency (EPA). Updated characterizations of MTBE CP, and its uncertainty, are currently needed to address a variety of decision goals concerning historical and current MTBE contamination. To this end, an extensive review of data sets bearing on MTBE and metabolite genotoxicity, cytotoxicity, and tumorigenicity was applied to reassess MTBE CP and related uncertainty in view of MOA considerations. Adopting the traditional approach that cytotoxicity-driven cancer MOAs are inoperative at very low, non-cytotoxic dose levels, it was determined that MTBE most likely does not increase cancer risk unless chronic exposures induce target-tissue toxicity, including in sensitive individuals. However, the corresponding expected (or plausible upper bound) CP for MTBE conditional on a hypothetical linear (e.g., genotoxic) MOA was estimated to be ∼2 × 10(-5) (or 0.003) per mg MTBE per kg body weight per day for adults exposed chronically over a lifetime. Based on this conservative estimate of CP, if MTBE is carcinogenic to humans, it is among the weakest 10% of chemical carcinogens evaluated by EPA.

Tissue microRNAs as predictive markers for gastric cancer patients undergoing palliative chemotherapy

MicroRNAs have the potential to become valuable predictive markers for gastric cancer. Samples of biopsy tissue, routinely taken from gastric cancer patients undergoing palliative chemotherapy, constitute suitable material for microRNA profiling with the aim of predicting the effect of chemotherapy. Our study group consisted of 54 patients, all of whom underwent palliative chemotherapy based on 5-fluorouracil (5-FU) or 5-FU in combination with platinum derivatives between 2000 and 2013. The expression of 29 selected microRNAs and genes BRCA1, ERCC1, RRM1 and TS, in gastric cancer tissue macrodissected from FFPE tissue samples, was measured by quantitative RT-PCR. The relationship between gene expression levels and time to progression (TTP) and overall survival (OS) was analysed. From the set of the 29 microRNAs of interest, we found high expression of miR-150, miR-342-3p, miR-181b, miR-221, miR-224 and low levels of miR-520h relate to shorter TTP. High levels of miR-150, miR-192, miR-224, miR-375 and miR-342-3p related to shorter OS. In routinely available FFPE tissue samples, we found 6 miRNAs with a relation to TTP, which may serve as predictors of the effectiveness of palliative treatment in gastric cancer patients. These miRNAs could also help in deciding whether to indicate palliative chemotherapy.

A microRNA-mediated decrease in eukaryotic initiation factor 2α promotes cell survival during PS-341 treatment

MicroRNAs (miRs) play pivotal roles in carcinogenesis and endoplasmic reticulum (ER) that performs the folding, modification and trafficking of proteins targeted to the secretory pathway. Cancer cells often endure ER stress during tumor progression but use the adaptive ER stress response to gain survival advantage. Here we report: (i) A group of miRs, including miR-30b-5p and miR-30c-5p, are upregulated by proteasome inhibitor PS-341 treatment, in HepG2 and MDA-MB-453 cells. (ii) Two representative PS-341-induced miRs: miR-30b-5p and miR-30c-5p are found to promote cell proliferation and anti-apoptosis in both tumor cells. (iii) eIF2α is confirmed as the congenerous target of miR-30b-5p and miR-30c-5p, essential to the anti-apoptotic function of these miRs. (iv) Upregulation of miR-30b-5p or miR-30c-5p, which occurs latter than the increase of phosphorylated eIF2α (p-eIF2α) in the cell under ER stress, suppresses the p-eIF2α/ATF4/CHOP pro-apoptotic pathway. (v) Inhibition of the miR-30b-5p or miR-30c-5p sensitizes the cancer cells to the cytotoxicity of proteasome inhibition. In conclusion, we unravels a new miRs-based mechanism that helps maintain intracellular proteostasis and promote cell survival during ER stress through upregulation of miR-30b-5p and miR-30c-5p which target eIF2α and thereby inhibit the p-eIF2α/ATF4/CHOP pro-apoptotic pathway, identifying miR-30b-5p and miR-30c-5p as potentially new targets for anti-cancer therapies.

Overexpression of miR-664 is associated with enhanced osteosarcoma cell migration and invasion ability via targeting SOX7

Osteosarcoma (OS) is one of the most common types of primary sarcoma of bone in children and young adults, and the long-term prognosis for OS patients still remains dismal due to the lack of effective early diagnostic biomarkers. Identifying sensitive and specific biomarkers in carcinogenesis may improve diagnostic and therapeutic strategies for this malignancy. The expression of miR-664 in osteosarcoma cell lines and osteosarcoma tissues was examined using real-time PCR. The effects of miR-664 on osteosarcoma cell migration and invasion were evaluated by cell invasion assays, migration assays, and three-dimension spheroid invasion assay. The effect of miR-664 on SOX7 was determined by luciferase assays and Western blot assay. The clinical association between miR-664 and SOX7 was analyzed by real-time PCR and Western blot assay. Expression of miR-664 was found to be upregulated in OS cell lines and tissues. Overexpression of miR-664 was associated with increased migration and invasive abilities of OS cells in vitro, whereas downregulation of miR-664 appeared to inhibit their migration and invasive potential. Furthermore, using biological approaches, we showed that miR-664 directly targeted and suppressed expression of the tumor suppressor SOX7. Additionally, the expression of miR-664 was negatively correlated with SOX7 expression in OS clinical tissues. Our findings suggest that miR-664 functions as an oncogene miRNA and has an important role in promoting human OS cell invasion and migration by suppressing SOX7 expression. Consequently, miR-664 may have potential as a novel diagnostic and therapeutic target of osteosarcoma.

miR-126 inhibits papillary thyroid carcinoma growth by targeting LRP6

microRNA-126 (miR-126) has been reported to play tumor suppressor roles in various types of cancers. Although it has been reported that miR-126 expression is downregulated in papillary thyroid carcinoma (PTC), the precise role and underlying molecular mechanism of miR-126 in PTC remains unclear. Therefore, the aims of the present study were to investigate the role and potential mechanism of miR-126 in tumorigenicity of PTC in vivo and in vitro. We observed that the miR-126 expression level was significantly downregulated in PTC tissue and PTC cell lines, the aberrant expression of miR-126 was correlated with lymph node metastasis, tumor size and TNM stage. We also showed that restoration of miR-126 in PTC cells inhibited cell proliferation, colony formations, migration and invasion, promoted cell apoptosis and cell cycle arrest at G1 stage in vitro, as well as inhibited tumor growth and decreased tumor volume and weight in vivo. Furthermore, low-density lipoprotein receptor‑related protein 6 (LRP6), a regulator of the Wnt/β‑catenin signaling cascade, was identified as a crucial target gene of miR-126. Overexpression of miR-126 inhibited LP6 expression on mRNA and protein levels, and deactivate Wnt/β-catenin signaling pathway. These results suggested that miR-126 functions as a tumor-suppressive miRNA by targeting LRP6 regulating Wnt/β-catenin signaling pathway and represents a therapeutic target for PTC.

MiRNA-615-5p functions as a tumor suppressor in pancreatic ductal adenocarcinoma by targeting AKT2

Background

Aberrant microRNA (miRNA) expression is associated with tumor development. This study aimed to elucidate the role of miR-615-5p in the development of pancreatic ductal adenocarcinoma (PDAC).

Methods

Locked nucleic acid in situ hybridization (LNA-ISH) was performed to compare miR-615-5p expression in patients between PDAC and matched adjacent normal tissues. Effects of miR-615-5p overexpression on cell proliferation, apoptosis, colony formation, migration, and invasion were determined in the pancreatic cancer cell lines PANC-1 and MIA PaCa-2. Effects of miR-615-5p on AKT2 were examined by dual-luciferase reporter assay. Lentivirus expressing miR-615 was used to create stable overexpression cell lines, which were subsequently used in mouse xenograft and metastasis models to assess tumor growth, apoptosis and metastasis.

Results

miR-615-5p expression was significantly lower in PDAC than in adjacent normal tissues. Low levels of miR-615-5p were independently associated with poor prognosis (HR: 2.243, 95% CI: 1.190-4.227, P=0.013). AKT2 protein expression was inversely correlated with miR-615-5p expression (r=-0.3, P=0.003). miR-615-5p directly targeted the 3’-untranslated region of AKT2 mRNA and repressed its expression. miR-615-5p overexpression inhibited pancreatic cancer cell proliferation, migration, and invasion in vitro, and tumor growth and metastasis in vivo. Furthermore, miR-615-5p overexpression also induced pancreatic cancer cell apoptosis both in vitro and in vivo.

Conclusions

These results show that miR-615-5p inhibits pancreatic cancer cell proliferation, migration, and invasion by targeting AKT2. The data implicate miR-615-5p in the prognosis and treatment of PDAC.

MiR-886-5p inhibition inhibits growth and induces apoptosis of MCF7 cells

BACKGROUND AND AIMS

To explore the molecular mechanisms of miR-886-5p in breast cancer., we examined roles in inhibiting growth and migration of MCF-7 cells.

METHODS

MiR-886-5p mimics and inhibitors were used to express or inhibit MiR-886-5p, respectively, and MTT and clone formation assays were used to determine the survival and proliferation. Hoechst 33342/ PI double staining was applied to detect apoptosis. The expression of caspase-3, caspase-8, caspase-9, MT1-MMP, VEGF-C and VEGF-D was detected by Western blotting, and the levels of MMP2 and MMP9 secreted from MCF-7 cells were assessed by ELISA. MCF-7 cell migration was determined by wound healing and Transwell assays.

RESULTS

We found that the growth of MCF-7 cells was inhibited upon decreasing miR-886-5p levels. Inhibiting miR-866-5p also significantly induced apoptosis and decreased the migratory capacity of these cells. The expression of VEGF-C, VEGF-D, MT1-MMP, MMP2, and MMP9 was also found to be decreased as compared to controls.

CONCLUSIONS

Our data show that downregulation of miR-886-5p expression in MCF-7 cells could significantly inhibit cell growth and migration. This might imply that inhibiting miR-886-5p could be a therapeutic strategy in breast cancer.

miR-202 suppresses cell proliferation in human hepatocellular carcinoma by downregulating LRP6 post-transcriptionally

MicroRNAs have emerged as important regulators of carcinogenesis. In the current study, we observed that microRNA-202 (miR-202) is downregulated in hepatocellular carcinoma (HCC) cells and tissues, indicating a significant correlation between miR-202 expression and HCC progression. Overexpression of miR-202 in HCC cells suppressed cell proliferation and tumorigenicity, while downregulation of miR-202 enhanced the cells' proliferative capacity. Furthermore, we identified low-density lipoprotein receptor-related protein 6 (LRP6) as a direct target of miR-202. miR-202 suppresses the expression of LRP6 by binding to the 3'-untranslated region (UTR) of its mRNA. Finally, we found that silencing the expression of LRP6 is the essential biological function of miR-202 during HCC cell proliferation. Collectively, our findings reveal that miR-202 is a potential tumor suppressive miRNA that participates in carcinogenesis of human HCC by suppressing LRP6 expression.

Mir-184 post-transcriptionally regulates SOX7 expression and promotes cell proliferation in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common human malignancies and the third leading cause of cancer mortality worldwide. The development and progression of HCC is a complicated process, involving the deregulation of multiple genes that are essential to cell biological processes. Recently, microRNAs (miRNAs) have been suggested to be closely associated with tumorigenesis. Our study showed that miR-184 is upregulated in HCC cell lines and tissues. Overexpression of miR-184 in HCC cells increased cell proliferation, tumorigenicity, and cell cycle progression, whereas inhibition of miR-184 reduced cell proliferation, tumorigenicity, and cell cycle progression. Additionally, we identified SOX7 as a direct target of miR-184. Ectopic expression of miR-184 led to downregulation of the SOX7 protein, resulting in upregulation of c-Myc, Cyclin D1, and phosphorylation of Rb. Our findings suggested that miR-184 represents a potential onco-miR and plays an important role in HCC progression by suppressing SOX7 expression.

Absence of mature microRNAs inactivates the response of gene expression to carcinogenesis induced by N-ethyl-N-nitrosourea in mouse liver

This study aims to evaluate the role of microRNAs (miRNAs) in chemical tumorigenesis by evaluating genomic gene expression in miRNA knockout mice. Previous studies showed that mice without mature miRNAs due to hepatocyte-specific Dicer1 knockout (KO) had a much higher liver tumor incidence than wild-type mice. In this study, Dicer1 KO or the wild-type mice were treated intraperitoneally with genotoxic carcinogen N-ethyl-N-nitrosourea (ENU) at a single dose (150 mg kg(-1) that resulted in liver tumorigenesis) or the vehicle at 3 weeks of age. The animals were killed 2 weeks after treatment and the liver samples were collected for the gene expression study. Principal components analysis and hierarchical cluster analysis showed that gene expression was globally altered by the Dicer1 KO and ENU exposure. There were 5621, 3286 and 2565 differentially expressed genes for Dicer1 disruption, ENU treatment in wild-type mice and ENU treatment in Dicer1 KO mice, respectively. Functional analysis of the differentially expressed genes suggests that the Dicer1 KO mouse liver lost their capability to suppress the carcinogenesis induced by ENU exposure in genomic level. In addition, the miRNA-mediated BRCA1 and P53 signaling pathways were identified as the main pathways responsible for the tumorigenesis. We conclude that the mouse livers in the absence of mature miRNAs could not appropriately respond to carcinogenic insults from ENU treatment, indicating that miRNAs play a critical role in chemical carcinogenesis.

Cell-Free microRNA-214 From Urine as a Biomarker for Non-Muscle-Invasive Bladder Cancer

PURPOSE

MicroRNAs are small noncoding RNAs and microRNA-214 (miR-214) has been associated with the inhibition of cancer cell growth, migration, and invasion. The aim of this study was to investigate whether cell-free miR-214 isolated from urine could be used as a biomarker for non-muscle-invasive bladder cancer (NMIBC).

MATERIALS AND METHODS

A total of 138 patients with primary NMIBC and 144 healthy normal controls were enrolled in this study. By use of quantitative polymerase chain reaction (PCR), the urinary levels of cell-free miR-214 were measured and the clinicopathological parameters of patients with NMIBC were compared with those of the controls.

RESULTS

The urinary levels of cell-free miR-214 were significantly higher in the NMIBC patients than in the controls (20.08±3.21 vs. 18.96±2.68, p=0.002). However, the urinary levels of cell-free miR-214 were neither graded nor staged for the NMIBC patients (p>0.05, each). When we compared the urinary levels of cell-free miR-214 according to clinical outcomes, patients with recurrence had lower levels of miR-214 than did those with no recurrence (19.24±2.67 vs. 20.41±3.41, p=0.023). By contrast, there were no significant differences in the urinary level of cell-free miR-214 between the NMIBC patients showing progression and those showing no progression (p=0.919). Multivariate Cox regression analysis revealed that urinary levels of cell-free miR-214 were an independent predictor of NMIBC recurrence (hazard ratio, 2.011; 95% confidence interval, 1.027 to 3.937; p=0.041).

CONCLUSIONS

Urinary levels of cell-free miR-214 could be an independent prognostic parameter for NMIBC recurrence. Thus, urinary cell-free microRNA-214 might be a useful prognostic marker for NMI BC.

MicroRNA-199b-5p is involved in the Notch signaling pathway in osteosarcoma

MicroRNAs (miRNAs) play important roles in the development, differentiation, and function of different cell types and in the pathogenesis of various human diseases. miRNAs are differentially expressed in normal and cancer cells. The investigation of miRNA expression between healthy subjects and patients with osteosarcoma is crucial for future clinical trials. We performed miRNA microarray analysis on 8 formalin-fixed, paraffin-embedded osteosarcoma tissue samples. We confirmed the results of the microarray analysis using reverse transcription polymerase chain reaction. miRNA profiling of osteosarcoma tissue samples showed that expression of 10 miRNAs had increased 10-fold compared with normal controls. Among the 10 miRNAs, 3 miRNAs (miR-199b-5p, miR-338-3p, and miR-891a) were confirmed to have been up-regulated by reverse transcription polymerase chain reaction. After transfection of 4 osteosarcoma cell lines with miR-199b-5p inhibitor, the expression of Notch pathway components in the transfected cell lines was changed. These results revealed that miR-199b-5p plays a role in Notch signaling in osteosarcoma. Recently, the inhibition of Notch and HES1 signaling has been suggested as a potential therapeutic strategy to prevent metastasis in human osteosarcoma. Taken together with our results, we suggest that miR-199b-5p inhibitor may also be a therapeutic option for osteosarcoma.

The prediction of the porcine pre-microRNAs in genome-wide based on support vector machine (SVM) and homology searching

Background

MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression by targeting mRNAs for translation repression or mRNA degradation. Although many miRNAs have been discovered and studied in human and mouse, few studies focused on porcine miRNAs, especially in genome wide.

Results

Here, we adopted computational approaches including support vector machine (SVM) and homology searching to make a global scanning on the pre-miRNAs of pigs. In our study, we built the SVM-based porcine pre-miRNAs classifier with a sensitivity of 100%, a specificity of 91.2% and a total prediction accuracy of 95.6%, respectively. Moreover, 2204 novel porcine pre-miRNA candidates were found by using SVM-based pre-miRNAs classifier. Besides, 116 porcine pre-miRNA candidates were detected by homology searching.

Conclusions

We identified the porcine pre-miRNA in genome-wide through computational approaches by utilizing the data sets of pigs and set up the porcine pre-miRNAs library which may provide us a global scanning on the pre-miRNAs of pigs in genome level and would benefit subsequent experimental research on porcine miRNA functional and expression analysis.

Efficient tumorigenesis by mutation-induced failure to terminate microRNA-mediated adaptive hyperplasia

Seven current contending cancer theories consider different sets of critical events as sufficient for tumorigenesis. These theories, most recently the microRNA dysregulation (MRD) theory, have overlapping attributes and extensive empirical support, but also some discrepancies, and some do not address both benign and malignant tumorigenesis. By definition, the most efficient tumorigenic pathways will dominate under conditions that selectively activate those pathways. The MRD theory provides a mechanistic basis to combine elements of the current theories into a new hypothesis that: (i) tumors arise most efficiently under stress that induces and sustains either protective or regenerative states of adaptive hyperplasia (AH) that normally are epigenetically maintained unless terminated; and (ii) if dysregulated by a somatic mutation that prevents normal termination, these two AH states can generate benign and malignant tumors, respectively. This hypothesis, but not multistage cancer theory, predicts that key participating AH-stem-cell populations expand markedly when triggered by stress, particularly chronic metabolic or oxidative stress, mechanical irritation, toxic exposure, wounding, inflammation, and/or infection. This hypothesis predicts that microRNA expression patterns in benign vs. malignant tumor tissue will correlate best with those governing protective vs. regenerative AH in that tissue, and that tumors arise most efficiently inmutagen-exposed stem cells that either happen to be in, or incidentally later become recruited into, an AH state.

In vivo imaging of oligonucleotide delivery

RNA interference (RNAi) has rapidly become a powerful tool for drug-target discovery and therapeutics. Cancer is an important application for RNAi therapeutics, since abnormal gene regulation is thought to contribute to the pathogenesis and maintenance of the metastatic phenotype of cancer. Many oncogenic genes present enticing therapeutic target possibilities for RNAi. Small interfering RNA (siRNA) and microRNA (miRNA) are potent and specific examples of RNAi are able to silence tumor-related genes and multiple oncogenic pathways and appear to be a rational approach to inhibit tumor growth. In subsequent in vivo studies, an appropriate animal model must be developed for a better evaluation of gene-silencing effects on tumors. How to evaluate the effect of siRNA and miRNA in an in vivo therapeutic model is also important. Bioluminescence imaging is an optical imaging method that can evaluate RNAi in vivo.

Contribution of microRNAs to radio- and chemoresistance of brain tumors and their therapeutic potential

Glioblastomas, particularly high grade brain tumors such as glioblastoma multiforme, are characterized by increased anaplasy, malignancy, proliferation, and invasion. These tumors exhibit high resistance to radiation therapy and treatment with anti-cancer drugs. The radio- and chemoresistance of gliomas is attributed to cancer stem cells (CSCs) that are considered as major contributors for maintenance and propagation of tumor cell mass, cancer malignancy and invasiveness, and tumor cell survival after courses of radiotherapy and medical interventions. MicroRNAs (miRNAs), key post-transcriptional gene regulators, have altered expression profiles in gliomas. Some of miRNAs whose expression is markedly up-regulated in brain tumors are likely to have a pro-oncogenic role through supporting growth, proliferation, migration, and survival of cancer stem and non-stem cells. In contrast, a population of miRNA possessing anti-tumor effects is suppressed in gliomas. In this review, we will consider miRNAs and their influence on radio- and chemoresistance of gliomas. These miRNAs harbor a great therapeutic significance as potent agents in future targeted anti-cancer therapy to sensitize glioma tumor cells and CSCs to cytotoxic effects of radiation exposure and treatment with anti-cancer drugs.

Decreased microRNA-214 levels in breast cancer cells coincides with increased cell proliferation, invasion and accumulation of the Polycomb Ezh2 methyltransferase

MicroRNAs (miRNAs) are small non-coding RNAs, which regulate gene expression by inhibiting translation or promoting degradation of specific target messenger RNAs (mRNAs). Alteration of the levels of a number of miRNAs is common in solid and hematological tumors. We have shown previously that miR-214 regulates Ezh2 in skeletal muscle and embryonic stem cells. The current study was aimed at examining the role of miR-214 in breast cancer where miR-214 levels are reduced but whether this phenomenon bears a functional relevance is unknown. MiR-214 expression was inversely correlated with Ezh2 mRNA and protein levels in breast cancer cell lines and at least one copy of the miR-214 alleles was found to be deleted in 24% (6/25) of primary breast tumors. Experimental increase of miR-214 in breast cancer cell lines correlated with reduction of Ezh2 protein levels, a known marker of invasion and aggressive breast cancer behavior. Supporting a direct targeting mechanism, miR-214 decreased luciferase activity from a construct containing the Ezh2 3' untranslated region. Expression of miR-214 specifically reduced cell proliferation of breast cancer cells and inhibited the invasive potential of a highly metastatic breast cancer cell line. These findings indicate that reduced miR-214 levels may contribute to breast tumorigenesis by allowing abnormally elevated Ezh2 accumulation and subsequent unchecked cell proliferation and invasion.

MicroRNAs and their predicted target messenger RNAs are deregulated by exposure to a carcinogenic dose of comfrey in rat liver

MicroRNAs (MiRNAs) are small noncoding RNAs that function as regulators of gene expression to control cell growth and differentiation. In this study, we analyzed miRNA and mRNA expression in the livers of rats treated with a carcinogenic dose of comfrey (Symphytum officinale) for 12 weeks. Groups of six rats were fed a normal diet or a diet containing 8% comfrey root. The animals were sacrificed 1 day after the last treatment and the livers were isolated for miRNA expression analysis using LC Sciences miRNA microarrays and for mRNA expression analysis using Affymetrix rat genome microarrays. MiRNA expression levels were significantly changed by comfrey treatment. The treated samples were separated clearly from the control samples in both principal component analysis (PCA) and hierarchical clustering analysis (HCA). Quantitative measurements of seven miRNAs using TaqMan real-time PCR were consistent with the microarray results in terms of fold-change and the direction of the change in expression. Forty-five miRNAs (P < 0.01) and 1,921 mRNAs (q = 0) were significantly changed by comfrey treatment. Using a target prediction algorithm, 434 differentially expressed genes (DEGs) were predicted to be targeted by the differentially expressed miRNAs (DEMs). The DEM-targeted DEGs were more likely to be involved in carcinogenesis than the DEGs that were not targeted by the DEMs. The nontargeted DEGs were enriched in noncancer-related biological processes. Our data suggest that comfrey may exert its carcinogenic effects by disturbing miRNA expression resulting in altered mRNA levels of the DEM-targeted genes that are functionally associated with carcinogenesis.

miR-338-3p suppresses invasion of liver cancer cell by targeting smoothened

MicroRNAs are involved in human carcinogenesis and cancer progression. Our previous study has shown that loss of miR-338-3p expression is associated with clinical aggressiveness of hepatocellular carcinoma (HCC). However, the exact roles and mechanisms of miR-338-3p remain unknown in HCC. To determine whether and how miR-338-3p influences liver cancer cell invasion, we studied miR-338-3p in the liver cancer cell lines, and we found that miR-338-3p is down-regulated in treated cells. Forced expression of miR-338-3p in SK-HEP-1 cells suppressed cell migration and invasion, whereas inhibition of miR-338-3p in SMMC-7721 cells induced cell migration and invasion. Furthermore, smoothened (SMO) was identified as a direct target of miR-338-3p. Forced expression of miR-338-3p down-regulated SMO and matrix metalloproteinase (MMP)-9 expression, but inhibition of miR-338-3p up-regulated SMO and MMP9 expression. However, small interfering RNA targeted SMO reversed the effects induced by blockade of miR-338-3p. SMO and MMP9 were overexpressed and associated with invasion and metastasis in HCC tissues. These data indicate that miR-338-3p suppresses cell invasion by targeting the smoothened gene in liver cancer in vitro and miR-338-3p might be a novel potential strategy for liver cancer treatment.

Increased expression of miR-34a in mouse spleen one day after exposure to N-ethyl-N-nitrosourea

MicroRNAs (miRNAs) are a class of single-stranded small RNA molecules (~22 nucleotides) that are not translated into proteins and function as regulators of gene expression. Many miRNAs are involved in carcinogenesis. One of them, miR-34a, is associated with various p53-initiated biological processes and may act as a tumor suppressor miRNA. Its expression is generally down-regulated in tumor tissues and up-regulated in tissues exposed to carcinogens chronically or subchronically. However, the response of this miRNA to acute exposure of a genotoxic carcinogen is little known. In this study, miR-34a expression was evaluated in spleen tissues of mice treated with a dose of 120 mg kg(-1) body weight N-ethyl-N-nitrosourea (ENU), a potent mutagenic carcinogen. Real-time PCR analysis showed that the ENU exposure resulted in a 5.5-fold increase of miR-34a expression over the control one day after the treatment. The result suggests that miR-34a expression responds sensitively to genotoxic insults within a short period after exposure of the mutagen, and therefore, this gene has the potential to be used as an indicator for genotoxin exposure.

Genomic analysis of microRNA time-course expression in liver of mice treated with genotoxic carcinogen N-ethyl-N-nitrosourea

BACKGROUND

Dysregulated expression of microRNAs (miRNAs) has been previously observed in human cancer tissues and shown promise in defining tumor status. However, there is little information as to if or when expression changes of miRNAs occur in normal tissues after carcinogen exposure.

RESULTS

To explore the possible time-course changes of miRNA expression induced by a carcinogen, we treated mice with one dose of 120 mg/kg N-ethyl-N-nitrosourea (ENU), a model genotoxic carcinogen, and vehicle control. The miRNA expression profiles were assessed in the mouse livers in a time-course design. miRNAs were isolated from the livers at days 1, 3, 7, 15, 30 and 120 after the treatment and their expression was determined using a miRNA PCR Array. Principal component analysis of the miRNA expression profiles showed that miRNA expression at post-treatment days (PTDs) 7 and 15 were different from those at the other time points and the control. The number of differentially expressed miRNAs (DEMs) changed over time (3, 5, 14, 32, 5 and 5 at PTDs 1, 3, 7, 15, 30 and 120, respectively). The magnitude of the expression change varied with time with the highest changes at PTDs 7 or 15 for most of the DEMs. In silico functional analysis of the DEMs at PTDs 7 and 15 indicated that the major functions of these ENU-induced DEMs were associated with DNA damage, DNA repair, apoptosis and other processes related to carcinogenesis.

CONCLUSION

Our results showed that many miRNAs changed their expression to respond the exposure of the genotoxic carcinogen ENU and the number and magnitude of the changes were highest at PTDs 7 to 15. Thus, one to two weeks after the exposure is the best time for miRNA expression sampling.

Chromosomal integration of adenoviral vector DNA in vivo

So far there has been no report of any clinical or preclinical evidence for chromosomal vector integration following adenovirus (Ad) vector-mediated gene transfer in vivo. We used liver gene transfer with high-capacity Ad vectors in the FAH(Deltaexon5) mouse model to analyze homologous and heterologous recombination events between vector and chromosomal DNA. Intravenous injection of Ad vectors either expressing a fumarylacetoacetate hydrolase (FAH) cDNA or carrying part of the FAH genomic locus resulted in liver nodules of FAH-expressing hepatocytes, demonstrating chromosomal vector integration. Analysis of junctions between vector and chromosomal DNA following heterologous recombination indicated integration of the vector genome through its termini. Heterologous recombination occurred with a median frequency of 6.72 x 10(-5) per transduced hepatocyte, while homologous recombination occurred more rarely with a median frequency of 3.88 x 10(-7). This study has established quantitative and qualitative data on recombination of adenoviral vector DNA with genomic DNA in vivo, contributing to a risk-benefit assessment of the biosafety of Ad vector-mediated gene transfer.

MicroRNA-221 regulates chondrogenic differentiation through promoting proteosomal degradation of slug by targeting Mdm2

MicroRNAs (miRNAs) are small RNAs that fulfill diverse functions by negatively regulating gene expression. Here, we investigated the involvement of miRNAs in the chondrogenic differentiation of chick limb mesenchymal cells and found that the expression of miR-221 increased upon chondrogenic inhibition. Blockade of miR-221 via peanut agglutinin-based antisense oligonucleotides reversed the chondro-inhibitory actions of a JNK inhibitor on the proliferation and migration of chondrogenic progenitors as well as the formation of precartilage condensations. We determined that mdm2 is a relevant target of miR-221 during chondrogenesis. miR-221 was necessary and sufficient to down-regulate Mdm2 expression, and this down-modulation of Mdm2 by miR-221 prevented the degradation of (and consequently up-regulated) the Slug protein, which negatively regulates the proliferation of chondroprogenitors. These results indicate that miR-221 contributes to the regulation of cell proliferation by negatively regulating Mdm2 and thereby inhibiting Slug degradation during the chondrogenesis of chick limb mesenchymal cells.

miRNAs in colon and rectal cancer: A consensus for their true clinical value

Numerous miRNAs are deregulated in human cancers and experimental evidence indicates that they can play roles as oncogenes or tumor suppressor genes. Colorectal cancer represents a wide and exciting area of research for molecular biology, due to the growing need of a molecular classification as well as prognostic and predictive molecular factors that may guide oncologists in the clinical management of patients. The aim of this review is to analyze the state of art of the miRNA expression profiles in colorectal cancer to explore some perspectives in this research field.

Functional FEN1 polymorphisms are associated with DNA damage levels and lung cancer risk

Flap endonuclease 1 (FEN1) is a key enzyme in maintaining genomic stability and protecting against carcinogenesis. This study investigated whether functional variations in FEN1 gene are associated with DNA damage and lung cancer risk. Thirty DNA samples were sequenced to identify variants and function of the variants was examined by a set of biochemical assays. DNA damage levels were detected by comet assays in a cohort of 303 coke-oven workers and 297 controls. The association with lung cancer risk was examined in two independent case-control panels consisted of a total 1,840 lung cancer patients and 1,958 controls. We identified two single nucleotide polymorphisms (SNPs) located in the FEN1 promoter c.-69G>A (rs174538:G>A) and 3'-untranslational region c.4150G>T (rs4246215:G>T) that were associated with reduced FEN1 expression. Among coke-oven workers, DNA damage levels were significantly higher in the -69GG or GA carriers compared with the -69AA carriers. The -69GG or 4150GG carriers had a significantly increased risk for developing lung cancer compared with the -69AA or 4150TT carriers. These results highlight FEN1 as an important gene in human carcinogenesis and genetic polymorphisms in FEN1 confer susceptibility to lung cancer.

Lin28 recruits the TUTase Zcchc11 to inhibit let-7 maturation in mouse embryonic stem cells

Lin28 and Lin28B, two developmentally regulated RNA-binding proteins and proto-oncogenes, selectively inhibit the maturation of let-7 family miRNAs in embryonic stem (ES) cells and certain cancers. Moreover, let-7 precursors (pre-let-7) were previously found to be terminally uridylated in a Lin28-dependent fashion. Here, we identify Zcchc11 (zinc finger, CCHC domain containing 11) as the 3′ terminal uridylyl transferase (TUTase) responsible for Lin28-mediated pre-let-7 uridylation and blockade of let-7 processing in mouse ES cells. We demonstrate that Zcchc11 activity is UTP-dependent, selective for let-7, and recruited by Lin28. Furthermore, knockdown of either Zcchc11 or Lin28, or overexpression of a catalytically inactive TUTase, relieves the selective inhibition of let-7 processing and leads to the accumulation of mature let-7 miRNAs and repression of let-7 target reporter genes. Our results establish a novel role for Zcchc11-catalyzed pre-let-7 uridylation in the control of miRNA biogenesis.

MicroRNAs in cholangiociliopathies

This review is focused on current findings implicating miRNAs in the polycystic liver diseases, which we categorized as cholangiociliopathies. Our recent data suggest that deregulation of miRNA pathways is emerging as a novel mechanism in the development of cholangiociliopathies. Experimental evidence demonstrates that miRNAs (i.e., miR-15a) influence hepatic cyst growth by affecting the expression of the cell cycle regulator, Cdc25A. Given that abnormalities in many cellular processes (i.e., cell cycle regulation, cell proliferation, cAMP and calcium signaling, the EGF-stimulated mitogen-activated protein kinase (MAPK) pathway and fluid secretion) contribute to the hepatic cystogenesis, the potential role of miRNAs in regulation of these processes is discussed.

At least ten genes define the imprinted Dlk1-Dio3 cluster on mouse chromosome 12qF1

Background

Genomic imprinting is an exception to Mendelian genetics in that imprinted genes are expressed monoallelically, dependent on parental origin. In mammals, imprinted genes are critical in numerous developmental and physiological processes. Aberrant imprinted gene expression is implicated in several diseases including Prader-Willi/Angelman syndromes and cancer.

Methodology/Principal Findings

To identify novel imprinted genes, transcription profiling was performed on two uniparentally derived cell lines, androgenetic and parthenogenetic primary mouse embryonic fibroblasts. A maternally expressed transcript termed Imprinted RNA near Meg3/Gtl2 (Irm) was identified and its expression studied by Northern blotting and whole mounts in situ hybridization. The imprinted region that contains Irm has a parent of origin effect in three mammalian species, including the sheep callipyge locus. In mice and humans, both maternal and paternal uniparental disomies (UPD) cause embryonic growth and musculoskeletal abnormalities, indicating that both alleles likely express essential genes. To catalog all imprinted genes in this chromosomal region, twenty-five mouse mRNAs in a 1.96Mb span were investigated for allele specific expression.

Conclusions/Significance

Ten imprinted genes were elucidated. The imprinting of three paternally expressed protein coding genes (Dlk1, Peg11, and Dio3) was confirmed. Seven noncoding RNAs (Meg3/Gtl2, Anti-Peg11, Meg8, Irm/“Rian”, AK050713, AK053394, and Meg9/Mirg) are characterized by exclusive maternal expression. Intriguingly, the majority of these noncoding RNA genes contain microRNAs and/or snoRNAs within their introns, as do their human orthologs. Of the 52 identified microRNAs that map to this region, six are predicted to regulate negatively Dlk1, suggesting an additional mechanism for interactions between allelic gene products. Since several previous studies relied heavily on in silico analysis and RT-PCR, our findings from Northerns and cDNA cloning clarify the genomic organization of this region. Our results expand the number of maternally expressed noncoding RNAs whose loss may be responsible for the phenotypes associated with mouse pUPD12 and human pUPD14 syndromes.

Detection of microRNA expression in human peripheral blood microvesicles

BACKGROUND

MicroRNAs (miRNA) are small non-coding RNAs that regulate translation of mRNA and protein. Loss or enhanced expression of miRNAs is associated with several diseases, including cancer. However, the identification of circulating miRNA in healthy donors is not well characterized. Microvesicles, also known as exosomes or microparticles, circulate in the peripheral blood and can stimulate cellular signaling. In this study, we hypothesized that under normal healthy conditions, microvesicles contain miRNAs, contributing to biological homeostasis.

METHODOLOGY/PRINCIPAL FINDINGS

Microvesicles were isolated from the plasma of normal healthy individuals. RNA was isolated from both the microvesicles and matched mononuclear cells and profiled for 420 known mature miRNAs by real-time PCR. Hierarchical clustering of the data sets indicated significant differences in miRNA expression between peripheral blood mononuclear cells (PBMC) and plasma microvesicles. We observed 71 miRNAs co-expressed between microvesicles and PBMC. Notably, we found 33 and 4 significantly differentially expressed miRNAs in the plasma microvesicles and mononuclear cells, respectively. Prediction of the gene targets and associated biological pathways regulated by the detected miRNAs was performed. The majority of the miRNAs expressed in the microvesicles from the blood were predicted to regulate cellular differentiation of blood cells and metabolic pathways. Interestingly, a select few miRNAs were also predicted to be important modulators of immune function.

CONCLUSIONS

This study is the first to identify and define miRNA expression in circulating plasma microvesicles of normal subjects. The data generated from this study provides a basis for future studies to determine the predictive role of peripheral blood miRNA signatures in human disease and will enable the definition of the biological processes regulated by these miRNA.

RNA silencing: small RNA-mediated posttranscriptional regulation of mRNA and the implications for heart electropathophysiology

Gene silencing refers to the "switching off" of genes within the cell: it can occur at transcriptional and posttranscriptional levels, controlling, respectively, how much mRNA is transcribed from each gene and how much protein is translated from this mRNA. Knowledge of its governing mechanisms is fundamental to our understanding of physiology; moreover, where there is a relevance for pathology, new diagnostic and therapeutic tools may be developed. Recently, families of noncoding RNA (ncRNA)-RNA that does not encode for a protein end-product--have been discovered that function as regulators of gene silencing. This has revolutionized biology by challenging the credence in the centrality of proteins as the regulators of biological processes, and is changing the way we study pathophysiology. In fact, a subfamily of small ncRNAs, called microRNA (miRNA), is now known as one of the most abundant class of regulatory molecules, and over one-third of human genes-including a growing number of key genes of the heart-may be targeted by one or more of the hundreds of miRNAs that exist. Here, we focus on how these small ncRNAs control translation, on the extraordinary consequences this class of regulator is currently known to have on aspects of cardiac excitability, and on the exciting therapeutic potential they have in this field.

Advances in molecular genetics and treatment of core-binding factor acute myeloid leukemia

PURPOSE OF REVIEW

Core-binding factor (CBF) acute myeloid leukemia (AML) is among the most common cytogenetic subtypes of AML, being detected in approximately 13% of adults with primary disease. Although CBF-AML is associated with a relatively favorable prognosis, only one-half of the patients are cured. Herein we review recent discoveries of genetic and epigenetic alterations in CBF-AML that may represent novel prognostic markers and therapeutic targets and lead to improvement of the still disappointing clinical outcome of these patients.

RECENT FINDINGS

Several acquired gene mutations and gene-expression and microRNA-expression changes that occur in addition to t(8;21)(q22;q22) and inv(16)(p13q22)/t(16;16)(p13;q22), the cytogenetic hallmarks of CBF-AML, have been recently reported. Alterations that may represent cooperative events in CBF-AML leukemogenesis include mutations in the KIT, FLT3, JAK2 and RAS genes, haploinsufficiency of the putative tumor suppressor genes TLE1 and TLE4 in t(8;21)-positive patients with del(9q), MN1 overexpression in inv(16) patients, and epigenetic and posttranscriptional silencing of CEBPA. Genome-wide gene-expression and microRNA-expression profiling identifying subgroups of CBF-AML patients with distinct molecular signatures, different clinical outcomes, or both, have also been reported.

SUMMARY

Progress has been made in delineating the genetic basis of CBF-AML that will likely result in improved prognostication and development of novel, risk-adapted therapeutic approaches.

Potential regulatory functions of microRNAs in the ovary

The interactions between ovarian germ and somatic cells and expression of several intraovarian autocrine/paracrine regulators are major contributing factors in the ovary. These intraovarian mediators regulate various ovarian cellular activities including cell growth, differentiation, and apoptosis, which are critical in follicular development. MicroRNAs (miRNAs) have emerged as key components of posttranscriptional gene expression. Recent evidence generated in mice implicates the regulatory function of miRNAs in oocyte maturation and ovarian follicular development. In the human, miRNAs may target specific gene expression in granulosa cells and participate in establishment and progression of ovarian cancer. Here, we review the currently available information on the expression and potential regulatory functions of miRNAs in the ovary under normal and pathologic conditions. Understanding the underlying mechanisms of how ovarian germ cell and somatic cell miRNAs are regulated and identifying their specific target genes and their functions may lead to the development of strategies to achieve target-specific gene regulation for the prevention and treatment of various ovarian disorders.

Microarray gene-expression profiling to predict lymph node metastasis in penile carcinoma

OBJECTIVE

To determine the value of gene-expression profiling as a predictor of the status of the regional nodes in patients with penile carcinoma.

PATIENTS AND METHODS

Tumour samples of 56 patients with penile squamous cell carcinoma were analysed for the gene expression on 35 k oligoarrays; 32 were from patients with histopathologically confirmed lymph node metastases and 24 from those with no lymph node involvement. The 56 patients were divided into a training and validation set. For the training set, 15 patients with histopathologically confirmed nodal metastases and 15 without were selected. The validation set consisted of the remaining 26 patients, containing 17 node-positive and nine with no nodal metastases.

RESULTS

A 44-probe classifier had the best performance within the training set; this classifier correctly assigned 29 of 30 specimens in the training set to the two outcome groups. In the validation set of 26 tumours, the classifier correctly assigned 14 of the 26 (54%) specimens to the two outcome groups. Of the 17 specimens with histologically confirmed nodal involvement, 12 were classified as node-positive and five as node-negative, resulting in a sensitivity of 71%. Of the nine specimens from node-negative patients, two were correctly classified as node-negative and seven as node positive, resulting in a specificity of 22%.

CONCLUSIONS

In this series, gene expression profiling did not produce a useful classifier to predict nodal involvement in patients with penile carcinoma.

Research progress of the relationship between microRNAs and p53 gene in oncogenesis

The initiation and development of oncogenesis are a multi-step and complicated process, in which activation of oncogenes and inactivation of tumor suppressor genes are involved. MicroRNAs (miRNAs) are a new class of endogenous, non-coding small RNA molecules. It has been demonstrated that their expression levels are closely associated with human pathogenesis of cancers. They may participate in regulating the abnormal expression of oncogenes and tumor suppressor genes. Mutation in tumor suppressor gene p53 is the most frequent phenomenon in human cancer, and up to now, almost 50% human cancers are demonstrated associated with p53 mutation. Recent studies showed that miRNAs might play a role in regulating the tumor-suppressor activity of p53 gene. In this review, the research progress in this field is discussed.