Suyang Zhang

miR-203 inhibits cell proliferation and migration of lung cancer cells by targeting PKCα.

PKCα (protein kinase C alpha, PRKCA) is an important protein involved in several steps of signaling pathways in lung cancer, and microRNAs (miRNAs) have also been shown to participate in lung carcinogenesis. However, it is not clear how PKCα and miRNAs are correlated in the disease. In this report, we aimed to identify novel miRNAs that target PKCα and to study their biological function. Using bioinformatics analysis, we predicted one novel candidate, miR-203, and found differential expression patterns of miR-203 and PKCα in human lung cancer tissues. Moreover, we experimentally validated miR-203 as a direct regulator of PKCα. Finally, we demonstrated that the targeting of PKCα by miR-203 played a critical role in regulating cell proliferation, apoptosis and migration in lung cancer cells. In summary, this study identifies a novel miRNA that targets PKCα and illustrates that the downregulation of PKCα by miR-203 modulates biological processes in lung cancer cells.

Effective detection and quantification of dietetically absorbed plant microRNAs in human plasma.

The detection of exogenous plant microRNAs in human/animal plasma/sera lies at the foundation of exploring their cross-kingdom regulatory functions. It is necessary to establish a standard operation procedure to promote study in this nascent field. In this study, 18 plant miRNAs were assessed in watermelon juice and mixed fruits by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). CT values, no-template controls and standard curves for each miRNA were used to evaluate the specificity and sensitivity of qRT-PCR and to obtain concentrations. Sixteen miRNAs were selected and measured in human plasma from volunteers after drinking juice. The CT values of 6 plant miRNAs in human plasma fell outside the linear ranges of their standard curves. The remaining 10 miRNAs were present at high basal levels, and 6 of them showed a dynamic physiological pattern in plasma (absorption rates of 0.04% to 1.31%). Northern blotting was used to confirm the qRT-PCR results. Critical issues such as RNA extraction and internal controls were also addressed.

miR-193a-3p Functions as a Tumor Suppressor in Lung Cancer by Down-regulating ERBB4

Background: ERBB4 plays an important role in the etiology and progression of lung cancer. Results: miR-193a-3p suppressed proliferation and invasion and promoted apoptosis in lung cancer cells and xenograft mice by negatively regulating ERBB4. Conclusion: miR-193a-3p exerted an anti-tumor effect by negatively regulating ERBB4 in lung cancer. Significance: This study may open new avenues for future lung cancer therapies. ERBB4, one of four ErbB receptor tyrosine kinase family members, plays an important role in the etiology and progression of lung cancer. In this study, we found that the ERBB4 protein levels were consistently up-regulated in lung cancer tissues, whereas the mRNA levels varied randomly, suggesting that a post-transcriptional mechanism was involved in regulating ERBB4 expression. Because microRNAs are powerful post-transcriptional regulators of gene expression, we used bioinformatic analyses to search for microRNAs that can potentially target ERBB4. We identified specific targeting sites for miR-193a-3p in the 3′-UTR of ERBB4. We further identified an inverse correlation between miR-193a-3p levels and ERBB4 protein levels, but not mRNA levels, in lung cancer tissue samples. By overexpressing or knocking down miR-193a-3p in lung cancer cells, we experimentally confirmed that miR-193a-3p directly recognizes the 3′-UTR of the ERBB4 transcript and regulates ERBB4 expression. Furthermore, the biological consequences of the targeting of ERBB4 by miR-193a-3p were examined in vitro via cell proliferation, invasion, and apoptosis assays and in vivo using a mouse xenograft tumor model. We demonstrated that the repression of ERBB4 by miR-193a-3p suppressed proliferation and invasion and promoted apoptosis in lung cancer cells and that miR-193a-3p exerted an anti-tumor effect by negatively regulating ERBB4 in xenograft mice. Taken together, our findings provide the first clues regarding the role of miR-193a-3p as a tumor suppressor in lung cancer through the inhibition of ERBB4 translation.

miR-203 Suppresses the Proliferation and Migration and Promotes the Apoptosis of Lung Cancer Cells by Targeting SRC

SRC, also known as proto-oncogene c-Src, is a non-receptor tyrosine kinase that plays an important role in cancer progression by promoting survival, angiogenesis, proliferation, and invasion pathways. In this study, we found that SRC protein levels were consistently upregulated in lung cancer tissues, but that SRC mRNA levels varied randomly, suggesting that a post-transcriptional mechanism was involved in SRC regulation. Because microRNAs (miRNAs) are powerful post-transcriptional regulators of gene expression, we used bioinformatic analyses to search for miRNAs that potentially target SRC. We identified specific targeting sites for miR-203 in the 3′-untranslated region (3′-UTR) of SRC. We then experimentally validated miR-203 as a direct regulator of SRC using cell transfection and luciferase assays and showed that miR-203 inhibited SRC expression and consequently triggered suppression of the SRC/Ras/ERK pathway. Finally, we demonstrated that the repression of SRC by miR-203 suppressed the proliferation and migration and promoted the apoptosis of lung cancer cells. In summary, this study provides the first clues regarding the role of miR-203 as a tumor suppressor in lung cancer cells through the inhibition of SRC translation.

MiR-143 and MiR-145 regulate IGF1R to suppress cell proliferation in colorectal cancer.

Insulin-like growth factor 1 receptor (IGF1R) is a transmembrane receptor that is activated by insulin-like growth factor 1 (IGF-1) and by a related hormone called IGF-2. It belongs to the large class of tyrosine kinase receptors and plays an important role in colorectal cancer etiology and progression. In this study, we used bioinformatic analyses to search for miRNAs that potentially target IGF1R. We identified specific target sites for miR-143 and miR-145 (miR-143/145) in the 3′-untranslated region (3′-UTR) of the IGF1R gene. These miRNAs are members of a cluster of miRNAs that have been reported to exhibit tumor suppressor activity. Consistent with the bioinformatic analyses, we identified an inverse correlation between miR-143/145 levels and IGF1R protein levels in colorectal cancer tissues. By overexpressing miR-143/145 in Caco2, HT29 and SW480 colorectal cancer cells, we experimentally validated that miR-143/145 directly recognizes the 3′-UTR of the IGF1R transcript and regulates IGF1R expression. Furthermore, the biological consequences of the targeting of IGF1R by miR-143/145 were examined by cell proliferation assays in vitro. We demonstrated that the repression of IGF1R by miR-143/145 suppressed the proliferation of Caco2 cells. Taken together, our findings provide evidence for a role of the miR-143/145 cluster as a tumor suppressor in colorectal cancer through the inhibition of IGF1R translation.

The origin, function, and diagnostic potential of extracellular microRNAs in human body fluids

Recently, numerous studies have documented the importance of microRNAs (miRNAs) as an essential cornerstone of the genetic system. Although RNA is usually considered an unstable molecule because of the ubiquitous ribonuclease, miRNAs are now known to circulate in the bloodstream and other body fluids in a stable, cell‐free form. Importantly, extracellular miRNAs are aberrantly present in plasma, serum, and other body fluids during the pathogenesis of many diseases and, thus, are promising noninvasive or minimally invasive biomarkers to assess the pathological status of the body. However, the origin and biological function of extracellular miRNAs remains incompletely understood. In this review, we summarize the recent literature on the biogenesis and working models of extracellular miRNAs, and we highlight the impact of extending these ongoing extracellular miRNA studies to clinical applications. WIREs RNA 2014, 5:285–300. doi: 10.1002/wrna.1208

The identification of novel targets of miR-16 and characterization of their biological functions in cancer cells

BackgroundIn eukaryotes, miR-16 is an important microRNA (miRNA) that is involved in numerous biological processes. However, it is not fully understood how miR-16 executes its physiological functions. In the present study, we aimed to identify novel miR-16 targets and study their biological functions.MethodsCandidate target genes of miR-16 were screened by microarray analysis of mRNA levels in several cancer cell lines with enhanced miR-16. Three bioinformatics algorithms, including TargetScan, PicTar, and miRanda, were used in combination to calculate the miR-16 targets. The expression levels of miR-16 and target mRNA were examined by relative quantification RT-PCR, and the expression levels of target protein were detected by Western blot. Luciferase reporter plasmids were constructed to confirm direct targeting. The effect of miR-16 and target gene on cell viability was evaluated using MTT assays. The effects of miR-16 and target gene on apoptosis and cell cycle distribution were evaluated by flow cytometry analysis.ResultsBy overexpressing miR-16 in several cancer cell lines and measuring global mRNA levels using microarray analysis, we identified 27 genes that may be regulated by miR-16. After the bioinformatics filtering process, 18 genes were selected as candidate miR-16 targets. Furthermore, we experimentally validated three of these candidates, MAP7 (microtubule-associated protein 7), PRDM4 (PR domain containing 4) and CDS2 (CDP-diacylglycerol synthase 2), as direct targets of miR-16. Finally, we demonstrated that miR-16 targeting MAP7 played a critical role in regulating proliferation but not apoptosis and cell cycle progression in cancer cells.ConclusionIn summary, the present study identifies several novel miR-16 targets and illustrates a novel function of miR-16 targeting MAP7 in modulating proliferation in cancer cells.

Identification of Ebola virus microRNAs and their putative pathological function

Ebola virus (EBOV), a member of the filovirus family, is an enveloped negative-sense RNA virus that causes lethal infections in humans and primates. Recently, more than 1000 people have been killed by the Ebola virus disease in Africa, yet no specific treatment or diagnostic tests for EBOV are available. In this study, we identified two putative viral microRNA precursors (pre-miRNAs) and three putative mature microRNAs (miRNAs) derived from the EBOV genome. The production of the EBOV miRNAs was further validated in HEK293T cells transfected with a pcDNA6.2-GW/EmGFP-EBOV-pre-miRNA plasmid, indicating that EBOV miRNAs can be produced through the cellular miRNA processing machinery. We also predicted the potential target genes of these EBOV miRNAs and their possible biological functions. Overall, this study reports for the first time that EBOV may produce miRNAs, which could serve as non-invasive biomarkers for the diagnosis and prognosis of EBOV infection and as therapeutic targets for Ebola viral infection treatment.

microRNA-200b and microRNA-200c promote colorectal cancer cell proliferation via targeting the reversion-inducing cysteine-rich protein with Kazal motifs

MicroRNA-200b and microRNA-200c (miR-200b/c) are 2 of the most frequently upregulated oncomiRs in colorectal cancer cells. The role of miR-200b/c during colorectal tumorigenesis, however, remains unclear. In the present study, we report that miR-200b/c can promote colorectal cancer cell proliferation via targeting the reversion-inducing cysteine-rich protein with Kazal motifs (RECK). Firstly, bioinformatics analysis predicted RECK as a conserved target of miR-200b/c. By overexpressing or knocking down miR-200b/c in colorectal cancer cells, we experimentally validated that miR-200b/c are direct regulators of RECK. Secondly, an inverse correlation between the levels of miR-200b/c and RECK protein was found in human colorectal cancer tissues and cell lines. Thirdly, we demonstrated that repression of RECK by miR-200b/c consequently triggered SKP2 (S-phase kinase-associated protein 2) elevation and p27Kip1 (also known as cyclin-dependent kinase inhibitor 1B) degradation in colorectal cancer cells, which eventually promotes cancer cell proliferation. Finally, promoting tumor cell growth by miR-200b/c-targeting RECK was also observed in the xenograft mouse model. Taken together, our results demonstrate that miR-200b/c play a critical role in promoting colorectal tumorigenesis through inhibiting RECK expression and subsequently triggering SKP2 elevation and p27Kip1 degradation.

Systematic characterization of seminal plasma piRNAs as molecular biomarkers for male infertility.

Although piwi-interacting RNAs (piRNAs) play pivotal roles in spermatogenesis, little is known about piRNAs in the seminal plasma of infertile males. In this study, we systematically investigated the profiles of seminal plasma piRNAs in infertile males to identify piRNAs that are altered during infertility and evaluate their diagnostic value. Seminal plasma samples were obtained from 211 infertile patients (asthenozoospermia and azoospermia) and 91 fertile controls. High-throughput sequencing technology was employed to screen piRNA profiles in seminal plasma samples pooled from healthy controls and infertile patients. The results identified 61 markedly altered piRNAs in infertile patient groups compared with control group. Next, a quantitative RT-PCR assay was conducted in the training and validation sets to measure and confirm the concentrations of altered piRNAs. The results identified a panel of 5 piRNAs that were significantly decreased in seminal plasma of infertile patients compared with healthy controls. ROC curve analysis and risk score analysis revealed that the diagnostic potential of these 5 piRNAs to distinguish asthenozoospermic and azoospermic individuals from healthy controls was high. In summary, this study identifies a panel of piRNAs that can accurately distinguish fertile from infertile males. This finding may provide pathophysiological clues about the development of infertility.