miRNA Expression Plasmids Research Articles

Treating cancer with microRNA replacement therapy: A literature review.

microRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally by interfering with the translation of one or more target mRNAs. The unique miRNA sequences are involved in many physiological and pathological processes. Dysregulation of miRNAs contributes to the pathogenesis of all types of cancer. Notably, the diminished expression of tumor suppressor miRNAs, such as members of the Let-7 and miR-34 family, promotes tumor progression, invasion and metastasis. The past lustrum in particular, has witnessed substantial improvement of miRNA replacement therapy. This approach aims to restore tumor suppressor miRNA function in tumor cells using synthetic miRNA mimics or miRNA expression plasmids. Here, we provide a comprehensive review of recent advances in miRNA replacement therapy for treatment of cancer and its advantages over conventional gene therapy. We discuss a wide variety of delivery methods and vectors, as well as obstacles that remain to be overcome. Lastly, we review efforts to reverse epigenetic alterations, which affect miRNA expression in cancer cells, and the promising observation that restoring miRNA function re-sensitizes resistant tumor cells to chemotherapeutic drugs. The fact that various miRNA replacement therapies are currently in clinical trial demonstrates the great potential of this approach to treat cancer.

Determinants of effective lentivirus-driven microRNA expression in vivo.

Manipulation of microRNA (miRNA) levels, including overexpression of mature species, has become an important biological tool, even motivating miRNA-based therapeutics. To assess key determinants of miRNA overexpression in a mammalian system in vivo, we sought to bypass the laborious generation of a transgenic animal by exploiting placental trophoblast-specific gene manipulation using lentiviral vectors, which has been instrumental in elucidating trophoblast biology. We examined the impact of several key components of miRNA stem loops and their flanking sequences on the efficiency of mature miRNA expression in vivo. By combining established and novel approaches for miRNA expression, we engineered lentivirus-driven miRNA expression plasmids, which we tested in the mouse placenta. We found that reverse sense inserts minimized single-strand splicing and degradation, and that maintaining longer, poly-A-containing arms flanking the miRNA stem-loop markedly enhanced transgenic miRNA expression. Additionally, we accomplished overexpression of diverse mammalian, drosophila, or C. elegans miRNAs, either based on native context or using a “cassette” replacement of the mature miRNA sequence. Together, we have identified primary miRNA sequences that are paramount for effective expression of mature miRNAs, and validated their role in mice. Principles established by our findings may guide the design of efficient miRNA vectors for in vivo use.

Induction of protection against foot-and-mouth disease virus in cell culture and transgenic suckling mice by miRNA targeting integrin αv receptor

Foot-and-mouth disease virus (FMDV) is an RNA virus that causes a highly contagious disease in domestic and wild cloven-hoofed animals. Although vaccination has been used to protect animals against FMDV, there are shortcomings in the efficacy of the available vaccines. RNA interference (RNAi) is triggered by small RNA molecules, including short interfering RNAs and microRNAs (miRNAs), and the use of RNAi-based methods have demonstrated promise as an alternative method of controlling the transmission of FMDV. However, the method of delivery, short duration of siRNA and miRNA in vivo, and the genetic variability of FMDV confound the use of RNAi-based strategies for FMDV control. FMDV has been shown to exploit host-cell integrins as cell-surface receptors to initiate infection. We selected the gene for the integrin αv subunit as an RNAi target, and constructed three αv-specific miRNA expression plasmids. The effects of these miRNAs on FMDV infection were examined in PK-15 cells and transgenic suckling mice. In PK-15 cells, the expression of the αv-specific miRNAs significantly inhibited the expression of integrin αv receptor and decreased FMDV infection. The transgenic mice were generated by integrating the αv-specific miRNA expression cassette using pronuclear microinjection. When challenged with a dose of FMDV ten times greater than the LD50, the survival rate of transgenic suckling mice was approximately six-fold higher than that of their non-transgenic littermates, indicating that the interference of the miRNAs significantly reduced FMDV infection in the transgenic mice. This is the first report of limiting FMDV attachment to cellular receptors using miRNA-mediated gene knock down of cell-surface receptors to significantly reduce FMDV infection in cell culture and transgenic suckling mice.

Multiple microRNAs targeted to internal ribosome entry site against foot-and-mouth disease virus infection in vitro and in vivo

BackgroundFoot-and-mouth disease virus (FMDV) causes a severe vesicular disease in domestic and wild cloven-hoofed animals. Because of the limited early protection induced by current vaccines, emergency antiviral strategies to control the rapid spread of FMD outbreaks are needed.Here we constructed multiple microRNAs (miRNAs) targeting the internal ribosome entry site (IRES) element of FMDV and investigated the effect of IRES-specific miRNAs on FMDV replication in baby hamster kidney (BHK-21) cells and suckling mice.ResultsFour IRES-specific miRNAs significantly reduced enhanced green fluorescent protein (EGFP) expression from IRES-EGFP reporter plasmids, which were used with each miRNA expression plasmid in co-transfection of BHK-21 cells. Furthermore, treatment of BHK-21 cells with Bi-miRNA (a mixture of two miRNA expression plasmids) and Dual-miRNA (a co-cistronic expression plasmid containing two miRNA hairpin structures) induced more efficient and greater inhibition of EGFP expression than did plasmids carrying single miRNA sequences.Stably transformed BHK-21 cells and goat fibroblasts with an integrating IRES-specific Dual-miRNA were generated, and real-time quantitative RT-PCR showed that the Dual-miRNA was able to effectively inhibit the replication of FMDV (except for the Mya98 strain) in the stably transformed BHK-21 cells.The Dual-miRNA plasmid significantly delayed the deaths of suckling mice challenged with 50× and 100× the 50% lethal dose (LD50) of FMDV vaccine strains of three serotypes (O, A and Asia 1), and induced partial/complete protection against the prevalent PanAsia-1 and Mya98 strains of FMDV serotype O.ConclusionThese data demonstrate that IRES-specific miRNAs can significantly inhibit FMDV infection in vitro and in vivo.

MiR-129-2 suppresses proliferation and migration of esophageal carcinoma cells through downregulation of SOX4 expression

We report the emerging role of microRNA (miRNA) deregulation associated with activation of an oncogene SOX4 (a member of the SRY-related HMG-box) in esophageal carcinoma. Paired esophageal cancer and adjacent non-tumor tissues were obtained from 42 patients who underwent primary surgical resection for esophageal cancer. Experiments such as real-time PCR, western blot analysis, luciferase-reporter assay, cell proliferation and colony formation assays, in vitro migration and invasion assays, and a wound-healing assay were performed to determine the effects of miR-129-2. We found that SOX4 expression was elevated (P<0.005) in esophageal tumors (n=42) when compared with its expression in the controls (n=42). Compared with the normal esophageal tissues, the expression of miR-129-2 was downregulated in 27 of 31 primary esophageal tumors, while the expression of SOX4 was upregulated (P<0.001). Restoration of miR-129-2 by transfection with an miRNA expression plasmid led to a decrease in SOX4 expression, which was accompanied by reduced migration and proliferation of the cancer cells. These results suggest that aberrant expression of SOX4 is associated with repression of miR-129-2, and restoration of miR-129-2 suppresses the migration and proliferation of esophageal cancer cells. Our results demonstrated that the deregulation of miR-129-2 leads to aberrant SOX4 expression, presenting a new paradigm in which the restoration of miRNA suppresses its oncogenic target in esophageal cancer.

Construction of miRNA expression vector dual-targeting on HIF-1α/survivin genes and its effects on proliferation of pancreatic cancer Panc-1 cell line

To design and construct miRNA expression vector dual-targeting on HIF-1α and survivin genes and to investigate its effects on proliferation of human pancreatic cancer cells. The specific pre-miRNA single strand DNA oligos for HIF-1 α and survivin genes were designed and synthesized, then via annealing and ligating with pcDNA6.2-GW/EmGFP-miR plasmids in order, two kinds (eight in total) of miRNA expression vectors for HIF-1α and survivin genes were constructed. The vectors, which were most effective to knockdown target genes, were screened with real-time RT-PCR and combined by chaining technology to construct dual-targeting plasmid. The recombined dual-targeting plasmid, mono-targeting plasmids and negative plasmid were transfected into Panc-1 cells, the suppression effect on two genes was identified by real-time RT-PCR, Western blot and MTT assays. The miRNA expression plasmids anti-H, anti-S and anti-H+S were successfully constructed by identification of sequencing analysis, and they were able to effectively inhibit the target genes expressing. MTT assays showed that the inhibition effect of dual-targeting vector anti-H+S was higher than that of mono-targeting vectors anti-H and anti-S 72 h after transfection (P<0.05). The effective miRNA expression vector dual-targeting on HIF-1α and survivin genes has been successfully constructed. The inhibition effect on proliferation of pancreatic cancer Panc-1 cells by dual-targeting plasmid was higher than that by mono-target plasmids.

Effective inhibition of foot-and-mouth disease virus (FMDV) replication in vitro by vector-delivered microRNAs targeting the 3D gene.

BackgroundFoot-and-mouth disease virus (FMDV) causes an economically important and highly contagious disease of cloven-hoofed animals. RNAi triggered by small RNA molecules, including siRNAs and miRNAs, offers a new approach for controlling viral infections. There is no report available for FMDV inhibition by vector-delivered miRNA, although miRNA is believed to have more potential than siRNA. In this study, the inhibitory effects of vector-delivered miRNAs targeting the 3D gene on FMDV replication were examined.ResultsFour pairs of oligonucleotides encoding 3D-specific miRNA of FMDV were designed and selected for construction of miRNA expression plasmids. In the reporter assays, two of four miRNA expression plasmids were able to significantly silence the expression of 3D-GFP fusion proteins from the reporter plasmid, p3D-GFP, which was cotransfected with each miRNA expression plasmid. After detecting the silencing effects of the reporter genes, the inhibitory effects of FMDV replication were determined in the miRNA expression plasmid-transfected and FMDV-infected cells. Virus titration and real-time RT-PCR assays showed that the p3D715-miR and p3D983-miR plasmids were able to potently inhibit the replication of FMDV when BHK-21 cells were infected with FMDV.ConclusionOur results indicated that vector-delivered miRNAs targeting the 3D gene efficiently inhibits FMDV replication in vitro. This finding provides evidence that miRNAs could be used as a potential tool against FMDV infection.

Abstract 1186: Identification of p53 regulatory microRNAs

Abstract Purpose: microRNAs (miRNAs) play very important roles in gene regulation, by interfering with target mRNA stability and/or translation. A number of specific miRNAs have been identified to function as oncogenes or tumor suppressors. We originally found that miR-192/-215 constitute part of the p53 tumor suppressor network and can act as effectors and regulators of p53. In this project, we aim to identify more p53-regulatory miRNAs to gain deeper insight into p53 regulation. Experiments: We developed an immunofluorescence-based screen to identify p53-regulatory miRNAs. Briefly, U2OS cells, an osteosarcoma cell line with wild type p53, were transfected with a collection of miRNA expression plasmids. The cellular levels of p53 were then evaluated by subsequent immunofluorescence analysis via high content BD pathway. Results: From our screen, we identified the known p53-regulatory miRNA miR-125b (Le et al., 2009), that can reduce the levels of p53, which in turn validated our screen method. Several other candidates identified from this screen are undergoing study in the context of the p53 tumor suppressor pathway. These miRNAs might be novel therapeutic targets for diagnosis and treatment of human cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1186. doi:10.1158/1538-7445.AM2011-1186

MiR-93 suppresses proliferation and colony formation of human colon cancer stem cells

To identify differentially expressed microRNAs (miRNAs) in human colon cancer stem cells (SW1116csc) and study their function in SW1116csc proliferation. SW1116csc were isolated from the human colon cancer cell line, SW1116 and cultured in serum-free medium. A miRNA microarray was used to detect differential expression profiles of miRNAs in SW1116csc and SW1116 cells. Real-time quantitative polymerase chain reaction (PCR) was performed to verify the differential expression of candidate miRNAs obtained from the microarray. Target mRNAs of differentially expressed miRNAs were predicted with target prediction tools. miRNA expression plasmids were transfected into SW1116csc using Lipofectamine 2000 reagent. Cell proliferation curves were generated with trypan blue staining, and the colony formation rate of transfected cells was measured with the soft agar colony formation assay. Expression of target mRNAs and proteins from differentially expressed miRNAs were detected using reverse transcription (RT)-PCR and western blotting. Compared with expression in SW1116 cells, 35 miRNAs (including hsa-miR-192, hsa-miR-29b, hsa-miR-215, hsa-miR-194, hsa-miR-33a and hsa-miR-32) were upregulated more than 1.5-fold, and 11 miRNAs (including hsa-miR-93, hsa-miR-1231, hsa-miRPlus-F1080, hsa-miR-524-3p, hsa-miR-886-3p and hsa-miR-561) were downregulated in SW1116csc. The miRNA microarray results were further validated with quantitative RT-PCR. miR-93 was downregulated, and its predicted mRNA targets included BAMBI, CCND2, CDKN1A, HDAC8, KIF23, MAP3K9, MAP3K11, MYCN, PPARD, TLE4 and ZDHHC1. Overexpressed miR-93 significantly inhibited cell proliferation and colony formation by SW1116csc. Furthermore, miR-93 negatively regulated the mRNA and protein levels of HDAC8 and TLE4. Some miRNAs were differentially expressed during differentiation of SW1116csc into SW1116 cells. miR-93 may inhibit SW1116csc proliferation and colony formation.

Screening for the differentially expressed proteins in human gallbladder cancer by two-dimensional gel electrophoresis and mass spectrometry and functional exploration of AnnexinA3

Objective To find potential molecular targets for gallbladder cancer diagnostics by analyzing and comparing the proteomes expressed in human gallbladder carcinoma and benign gallbladder tissues, and investigate whether annexinA3 down-regulation by miRNA leads to inhibition of proliferation and arrest of cell cycle in human gallbladder cancer cell line SGC-996. Methods The proteins expressed in these tissues were analyzed by the two-dimensional gel electrophoresis. Proteins expressed differently of a 2-fold change were cut and analyzed by MALDI-TOF/TOF mass spectrometry. After miRNA expression plasmid targeting to annexinA3 gene was constructed and transfected into cancer cells, the methyl thiazolyl tetrazolium ( MTT) assay was performed for measuring cell proliferation and flow cytometic analysis for cell cycle. Results Protein extracts of individual sample in each type of tissues were separated on two-dimensional gels. There were 46 differentially expressed proteins in the tissues of gallbladder cancer. Seventeen proteins were successfully identified by MS, in which 9 proteins were overexpressed in tumors and the rest 8 proteins were underexpressed, including Annexi-nA3, TTR protein, etc. After interfering annexinA3 in gallbladder cancer SGC-996 cell line, the cell proliferation was suppressed. Flow cytometry revealed that after interfering annexinA3 in gallbladder cancer SGC-996 cell line, the cells in G1 phase were increased, while those in S phase were declined as compared with control group (P<0.05). Conclusion Significant discrepancies in protein expression exist between gallbladder cancer tissues and benign gallbladder tissues. Some of the differentially expressed proteins found by the proteomic approach may be potential molecular targets for early diagnosis of gallbladder cancer. miRNA interfering to annexi-nA3 effectively reverses some of the malignant biological characters of gallbladder cancer cells. Key words: Carcinoma of gallbladder; Proteomic; Tumor markers; AnnexinA3; RNA interference