Effects of multiple-target anti-microRNA antisense oligodeoxyribonucleotides on proliferation and migration of gastric cancer cells

Therapeutic Targeting of Overexpressed MiRNAs in Cancer Progression

MicroRNAs (miRNAs) are non-coding RNAs involved in the modulation of various biological processes, and their dysregulation is greatly associated with cancer progression as miRNAs can act as either tumour suppressors or oncogenes, depending on their intended target, mechanism of actions, and expression levels. This review paper aims to shed light on the role of overexpressed miRNAs in cancer progression. Cancer cells are known to upregulate specific miRNAs to inhibit the expression of genes regulating the cell cycle, such as PTEN, FOXO1, SOX7, caspases, KLF4, TRIM8, and ZBTB4. Inhibition of these genes promotes cancer development and survival by inducing cell growth, migration, and invasion while evading apoptosis, which leads to poor cancer survival rates. Therefore, the potential of antisense miRNAs in treating cancer is also explored in this review. Antisense miRNAs are chemically modified oligonucleotides that can reverse the action of overexpressed miRNAs. Currently, the therapeutic potential of antisense miRNAs is being validated in both in vitro and in vivo models. Studies have shown that antisense miRNAs could slow down the progression of cancer while enhancing the action of conventional anticancer drugs. These findings provide hope for future oncologic care as this novel intervention is in the process of clinical translation.

Study of hsa_circRNA_000121 and hsa_circRNA_004183 in papillary thyroid microcarcinoma

We detected the expressions of hsa_circRNA_000121 and hsa_circRNA_ 004183 in papillary thyroid microcarcinoma (PTMC) and explored their relationship with the invasiveness of PTMC. PTMC patients with (n = 30; metastasis group) and without lymph node metastasis (n = 30; nonmetastasis group) were included. The levels of hsa_circRNA_000121, hsa_circRNA_004183, hsa-miR-4763, hsa-miR-6775, sarcoma gene (SRC), and MMP-14 were detected with real-time polymerase chain reaction. Receiver-operating characteristic (ROC) analyzed the diagnostic value of hsa_circRNA_000121 and hsa_circRNA_004183. Binary logistic regression analysis evaluated the relationship of gene expression with PTMC invasiveness. In PTMC tissue samples, compared with the metastasis group, the expression of hsa_circRNA_000121, hsa_circRNA_004183, SRC, and MMP-14 in the nonmetastasis group decreased, while the expression of hsa-miR-4763 and hsa-miR-6775 increased. In peripheral blood, compared with the metastasis group, the expression of hsa_circ_000121 and hsa_circRNA_004183 in the nonmetastasis group decreased. Both hsa_circRNA_000121 and hsa_circRNA_004183 had good sensitivity and specificity for diagnosing PTMC lymph node metastasis, with a cut-off value of 0.796 and 0.938, respectively. However, the gene expressions were not significantly associated with PTMC lymph node metastasis. Hsa_circRNA_000121 may upregulate SRC expression through hsa-miR-4763, while hsa_circRNA 000121 may upregulate MMP-14 expression through hsa-miR-6775, thereby promoting the aggressiveness of PTMC and ultimately leading to cervical lymph node metastasis. hsa_circRNA_000121 and hsa_circRNA_004183 may become potential biomarkers of PTMC aggressiveness.

miRNAs in Cancer (Review of Literature)

MicroRNAs (miRNAs) are short, noncoding, single-stranded RNA molecules that regulate gene expression at the post-transcriptional level by binding to mRNAs. miRNAs affect the course of processes of fundamental importance for the proper functioning of the organism. These processes include cell division, proliferation, differentiation, cell apoptosis and the formation of blood vessels. Altered expression of individual miRNAs has been shown in numerous cancers, which may indicate the oncogenic or suppressor potential of the molecules in question. This paper discusses the current knowledge about the possibility of using miRNA as a diagnostic marker and a potential target in modern anticancer therapies.

Integrin-Linked Kinase Silencing Induces a S/G2/M Phases Cell Cycle slowing and Modulates Metastasis-Related Genes in SGC7901 Humancc Gastric Carcinoma Cells

Background and aim

Integrin-linked kinase has been implicated in metastasis of human tumors. Recent studies have also shown that the down-regulation of integrin-linked kinase has anti-tumor potential by inhibiting the metastatic potential of several types of cultured human cancer cells. However, the mechanism by which integrin-linked kinase regulates metastasis in human gastric carcinoma is not fully clear. We investigated the effect of integrin-linked kinase deletion on metastasis-associated markers in human gastric carcinoma SGC-7901 cell lines.

Methods

We generated cell lines depleted for integrin-linked kinase. Cell adhesion and invasion were measured by the MTS assay and transwell assay. The cell cycle was measured by flow cytometry. Expression of metastasis-related genes was assessed by reporter assay, quantitative RT-PCR and western blotting.

Results

Our data showed an inhibitory effect on cell adhesion and invasion after silencing of integrin-linked kinase. The cell cycle was slowed in S/G2/M phases. Metastasis-related genes E-cadherin, MMP-2/9 and cystatin B, as well as the signaling molecules p-Akt, NF-κB, and AP-1 activation, were also modulated. Our results indicate that integrin-linked kinase plays an important role in metastasis of human gastric carcinoma cells.

Conclusions

Down-regulation of integrin-linked kinase resulted in the impairment of the metastatic potential of gastric tumor cells by regulating metastasis-related gene expression, by inhibiting the Akt pathway as well as the activity of transcription factors. Integrin-linked kinase could be used as a potential therapeutic target.

Potential Value of miR-221/222 as Diagnostic, Prognostic, and Therapeutic Biomarkers for Diseases

microRNAs (miRNAs) are short non-coding RNAs that regulate gene expression by base pairing with their target messenger RNAs. Dysregulation of miRNAs is involved in the pathological initiation and progression of many human diseases. miR-221 and miR-222 (miR-221/222) are two highly homologous miRNAs, and they are significantly overexpressed in several types of human diseases. Silencing miR-221/222 could represent a promising approach for therapeutic studies. In the present review, we will describe the potential value of miR-221/222 as diagnostic, prognostic, and therapeutic biomarkers in various diseases including cancer and inflammatory diseases.

Human Ribosomal RNA-Derived Resident MicroRNAs as the Transmitter of Information upon the Cytoplasmic Cancer Stress

Dysfunction of ribosome biogenesis induces divergent ribosome-related diseases including ribosomopathy and occasionally results in carcinogenesis. Although many defects in ribosome-related genes have been investigated, little is known about contribution of ribosomal RNA (rRNA) in ribosome-related disorders. Meanwhile, microRNA (miRNA), an important regulator of gene expression, is derived from both coding and noncoding region of the genome and is implicated in various diseases. Therefore, we performed in silico analyses using M-fold, TargetScan, GeneCoDia3, and so forth to investigate RNA relationships between rRNA and miRNA against cellular stresses. We have previously shown that miRNA synergism is significantly correlated with disease and the miRNA package is implicated in memory for diseases; therefore, quantum Dynamic Nexus Score (DNS) was also calculated using MESer program. As a result, seventeen RNA sequences identical with known miRNAs were detected in the human rRNA and termed as rRNA-hosted miRNA analogs (rmiRNAs). Eleven of them were predicted to form stem-loop structures as pre-miRNAs, and especially one stem-loop was completely identical with hsa-pre-miR-3678 located in the non-rDNA region. Thus, these rmiRNAs showed significantly high DNS values, participation in regulation of cancer-related pathways, and interaction with nucleolar RNAs, suggesting that rmiRNAs may be stress-responsible resident miRNAs which transmit stress-tuning information in multiple levels.

MicroRNAs as Biomarkers for Diagnosis, Prognosis and Theranostics in Prostate Cancer

Prostate cancer (PC) includes several phenotypes, from indolent to highly aggressive cancer. Actual diagnostic and prognostic tools have several limitations, and there is a need for new biomarkers to stratify patients and assign them optimal therapies by taking into account potential genetic and epigenetic differences. MicroRNAs (miRNAs) are small sequences of non-coding RNA regulating specific genes involved in the onset and development of PC. Stable miRNAs have been found in biofluids, such as serum and plasma; thus, the measurement of PC-associated miRNAs is emerging as a non-invasive tool for PC detection and monitoring. In this study, we conduct an in-depth literature review focusing on miRNAs that may contribute to the diagnosis and prognosis of PC. The role of miRNAs as a potential theranostic tool in PC is discussed. Using a meta-analysis approach, we found a group of 29 miRNAs with diagnostic properties and a group of seven miRNAs with prognostic properties, which were found already expressed in both biofluids and PC tissues. We tested the two miRNA groups on The Cancer Genome Atlas dataset of PC tissue samples with a machine-learning approach. Our results suggest that these 29 miRNAs should be considered as potential panel of biomarkers for the diagnosis of PC, both as in vivo non-invasive test and ex vivo confirmation test.

Mir-221/222 are promising targets for innovative anticancer therapy

INTRODUCTION

MicroRNAs (miRNAs) are key non-coding RNA post-transcriptional regulators of messenger RNAs (mRNAs), and are deeply dysregulated in human cancer. A rising body of evidence indicates that miRNAs represent valuable therapeutic targets. In this light, the cluster miR-221/222 are of particular relevance, given that they are strongly upregulated in a variety of solid and hematologic malignancies.

AREA COVERED

This review summarizes recent findings on the roles played by miR-221/222 in human cancer and their potential clinical value as promising targets for therapeutic studies.

EXPERT OPINION

The rising body of advanced preclinical evidence on the biological significance of miR-221/222 in a variety of malignancies indicates that they will play a crucial role in the future of innovative therapeutic strategies, both as validated biomarkers and targets.

Celastrol induces cell cycle arrest by MicroRNA-21-mTOR-mediated inhibition p27 protein degradation in gastric cancer

Objective

Celastrol has anti-cancer effects by increase of apoptosis of gastric cancer cells. However, its role in gastric cancer cell cycle is still unclear. The aim of this study was to investigate the effect and mechanism of celastrol on gastric cancer cell cycle.

Methods

The effects of celastrol on cell cycle in BGC-823 and MGC-803 cells were assayed via flow cytometry analysis. The expression of p27 and mTOR was detected by real-time PCR and western blot. The activity of mTOR and mTORC2 was measured by mTOR and mTORC2 kinase assays. miR-21 mimic was used to up-regulate miR-21 expression and mTOR expression plasmid was used to increase mTOR level in gastric cancer cells.

Results

Celastrol caused G2/M cell-cycle arrest that was accompanied by the down-regulation of miR-21 expression. In particular, miR-21 overexpression reversed cell cycle arrest effects of celastrol. Further study showed that celastrol increased levels of the p27 protein by inhibiting its degradation. miR-21 and mTOR signaling pathway was involved in the increase of p27 protein expression in BGC-823 and MGC-803 cells treated with celastrol. Significantly, miR-21 overexpression restored the decrease of mTOR activity in cells exposed celastrol.

Conclusions

The effect of celastrol on cell cycle arrest of gastric cancer cells was due to an increase of p27 protein level via inhibiting miR-21-mTOR signaling pathway.

MicroRNA-766 targeting regulation of SOX6 expression promoted cell proliferation of human colorectal cancer

MicroRNAs (miRNAs) have emerged as important regulators of cancer-cell biological processes. Previous studies have shown that miR-766 plays an important role in a variety of biological processes in various human cancers. However, the underlying mechanism of miR-766 in colorectal cancer (CRC) cells remains unclear. In this study, we investigated miR-766’s role in CRC cell proliferation. Polymerase chain reaction results showed that miR-766 expression was significantly upregulated in CRC tissues and cells. Ectopic expression of miR-766 promoted cell growth and anchorage-independent growth in CRC cells. Bioinformatic analysis predicted SOX6, a potential target of miR-766, acting as a tumor suppressor. Luciferase reporter assay results demonstrated that miR-766 directly bound to the 3′-untranslated region of SOX6. Overexpression of miR-766 suppressed SOX6 expression, resulting in the downregulation of p21 and upregulation of cyclin D1. In a further experiment, SOX6-silenced SW480 cells transfected with miR-766 promoted cell growth, suggesting that downregulation of SOX6 was required for miR-766-induced CRC cell proliferation. Taken together, these results suggested that miR-766 represents an onco-miRNA and participates in the development of CRC by modulating SOX6 expression.

MicroRNAs: biogenesis, roles for carcinogenesis and as potential biomarkers for cancer diagnosis and prognosis

MicroRNAs (miRNAs) are short non-coding RNAs of 20-24 nucleotides that play important roles in carcinogenesis. Accordingly, miRNAs control numerous cancer-relevant biological events such as cell proliferation, cell cycle control, metabolism and apoptosis. In this review, we summarize the current knowledge and concepts concerning the biogenesis of miRNAs, miRNA roles in cancer and their potential as biomarkers for cancer diagnosis and prognosis including the regulation of key cancer-related pathways, such as cell cycle control and miRNA dysregulation. Moreover, microRNA molecules are already receiving the attention of world researchers as therapeutic targets and agents. Therefore, in-depth knowledge of microRNAs has the potential not only to identify their roles in cancer, but also to exploit them as potential biomarkers for cancer diagnosis and identify therapeutic targets for new drug discovery.

Effects of microRNA-106 on proliferation of gastric cancer cell through regulating p21 and E2F5

OBJECTIVE

To investigate the effects of miR-106b on malignant characteristics of gastric cancer cells, and explore possible mechanisms.

METHODS

Expression of miR-106b, p21 and E2F was determined by real-time PCR. Transfection with miR-106b mimics was conducted, and gastric cancer cells with miR-106b overexpression were obtained. Cells transfected with mimic mutants and those without transfection served as negative and blank controls, respectively. Flow cytometry and transwell assays were adopted to detect the effects of miR-106b overexpression on cell cycle, migration and invasion of gastric cancer cells.

RESULTS

. The expression of miR- 106b in gastric cancer cells was significantly higher than that in normal gastric mucosa cells. Furthermore, the expression level of miR-106b rose according to the degree of malignacy among the three GC cell strains (MKN- 45 > SGC-7901 > MKN-28). Overexpression of miR-106b shortened the G0/G1 phase and accelerated cell cycle progression, while reducing p21 and E2F5, without any significant effects on the capacity for migration and invasion of gastric cancer cells.

CONCLUSIONS

miR-106b may promote cell cycling of gastric cancer cells through regulation of p21 and E2F5 target gene expression.

Using artificial microRNA sponges to achieve microRNA loss-of-function in cancer cells

Widely observed dysregulation of microRNAs (miRNAs) in human cancer has led to substantial speculation regarding possible functions of these short, non-coding RNAs in cancer development and manipulation of miRNA expression to treat cancer. To achieve miRNA loss-of-function, miRNA sponge technology has been developed to use plasmid or viral vectors for intracellular expression of tandemly arrayed, bulged miRNA binding sites complementary to a miRNA target to saturate its ability to regulate natural mRNAs. A strong viral promoter can be used in miRNA sponge vectors to generate high-level expression of the competitive inhibitor transcripts for either transient or long-term inhibition of miRNA function. Taking the advantage of sharing a common seed sequence by members of a miRNA family, this technology is especially useful in knocking down the expression of a family of miRNAs, providing a powerful means for simultaneous inhibition of multiple miRNAs of interest with a single inhibitor. Knockdown of overexpressed oncogenic miRNAs with the technology can be a rational therapeutic strategy for cancer, whereas inhibition of tumor-suppressive miRNAs by the sponges will be useful in deciphering functions of miRNAs in oncogenesis. Herein, we discuss the design of miRNA sponge expression vectors and the use of the vectors to gain better understanding of miRNA's roles in cancer biology and as an alternative tool for anticancer gene therapy.

Let-7b inhibits cell proliferation, migration, and invasion through targeting Cthrc1 in gastric cancer

Dysregulation of specific microRNAs (miRNAs) is found to play a vital role in carcinogenesis and progression of gastric cancer (GC). In the present study, we investigated the expression profiles of miRNAs in gastric cancer. Let-7b was found downregulated remarkably in gastric cancer tissues and was correlated with Helicobacter pylori infection, tumor stage, and lymphatic metastasis. Ectopic expression of let-7b suppressed the growth, migration, invasion, and tumorigenicity of GC cells, whereas let-7b knockdown promoted these phenotypes. Bioinformatic analysis predicted collagen triple helix repeat containing 1 (Cthrc1) as a direct target of let-7b. Luciferase assay showed that let-7b repressed the activity of Cthrc1 through binding its 3'UTR. Western blotting also confirmed that the protein levels of Cthrc1 were decreased by let-7b. Cthrc1 was significantly upregulated and reversely correlated with let-7b levels in GC. Co-expression of let-7b and Cthrc1 without its 3'UTR could rescue cell growth, migration, and invasion inhibited by let-7b. These results suggest that let-7b may directly target Cthrc1 and function as a tumor suppressor gene in GC.

miR-21 increases the programmed cell death 4 gene-regulated cell proliferation in head and neck squamous carcinoma cell lines

MicroRNAs (miRs) are small non-coding RNAs that regulate the translation of many genes in normal and cancer cells where they are frequently dysregulated promoting tumor progression. Several studies have illustrated the potential of manipulating miR expression in cancer research and therapy. The aim of the present study was to investigate expression patterns of a panel of miRs in head and neck squamous cell carcinoma (HNSCC) shown to be relevant in other carcinomas and to elucidate their role if dysregulated. We performed analysis of miR‑21, -200c, -138-1, -138-2, -25 and -34 expression by qRT-PCR in 6 HNSCC cell lines and computerized search for genetic targets of dysregulated miRNA-21 (miR‑21). Lipofection of mock and anti-miR-21 and determination of expression efficiencies and final programmed cell death 4 (PDCD4) expression were carried out by luciferase assay and western blotting. MTT assay was used to measure cell proliferation and flow cytometry was performed for cell cycle analysis. Expression of miR-21 was most prominently upregulated in the HNSCC cell lines, particularly in UM-SCC11B (6.45±0.25-fold, P<0.05) and UM-SCC9 (4.35±0.22-fold, P<0.05) as compared to primary epidermal keratinocytes used as control. The expression levels of the other miRs showed no difference except for miR-34 and -138-1 each in one cell line. Subsequent transfection of precursor miR-21 stimulated proliferation while anti-miR-21 inhibited proliferation of both cell lines. PDCD4 was identified with software designed for this purpose as potential target gene of miR-21. Subsequently, its role in HNSCC lines was experimentally confirmed by regulation of PDCD4 transfecting miR-21 mimics and anti-miR-21. Finally, we showed that PDCD4 is negatively regulated by miR-21 at the post-transcriptional level via binding to the 3'-untranslated region of PDCD4 mRNA. A role of upregulated miR-21 and reduced PDCD4 stimulating the proliferation was demonstrated in HNSCC lines and, in turn, transfection of anti-miR-21 upregulating PDCD4 reduced the cellular division rate. We explored miR-21 and PDCD4 expression as markers of progression and prognosis and for a potential translational value in the development of agents slowing growth of HNSCC and other carcinomas useful in palliative therapy or as a component of multi-modality treatments.

MicroRNAs in the Neural Retina

The health and function of the visual system rely on a collaborative interaction between diverse classes of molecular regulators. One of these classes consists of transcription factors, which are known to bind to DNA and control the transcription activities of their target genes. For a long time, it was thought that the transcription factors were the only regulators of gene expression. More recently, however, a novel class of regulators emerged. This class consists of a large number of small noncoding endogenous RNAs, namely, miRNAs. The miRNAs compose an essential component of posttranscriptional gene regulation, since they ultimately control the fate of gene transcripts. The retina, as a part of the central nervous system, is a well-established model for unraveling the molecular mechanisms underlying neuronal and glial functions. Numerous recent efforts have been made towards identification of miRNAs and their inferred roles in the visual pathway. In this review, we summarize the current state of our knowledge regarding the expression and function of miRNA in the neural retina and we discuss their potential uses as biomarkers for some retinal disorders.

Celastrol induces apoptosis of gastric cancer cells by miR-21 inhibiting PI3K/Akt-NF-κB signaling pathway

OBJECTIVE

Celastrol, a plant triterpene, has anticancer effects by increase of apoptosis. In the present study, the mechanism of celastrol on gastric cancer cell apoptosis was examined.

METHODS

The effect of celastrol on PI3K/Akt and the NF-κB signaling pathway was evaluated with Western blot and luciferase reporter assay. miR-21 expression was determined using real-time PCR. miR-21 inhibitor and miR-21 mimic were used to downregulate and upregulate miR-21 expression, respectively.

RESULTS

It was identified that celastrol was capable of inducing apoptosis of gastric cancer cells, which was mediated via inhibiting the activation of PI3K/Akt and NF-κB. A strong activator of Akt, IGF-1 restored NF-κB activity in cells treated with celastrol. Celastrol could also significantly suppress miR-21 expression. Furthermore, miR-21 inhibitor could decrease phospho-Akt expression and NF-κB activity. Notably, upregulation of miR-21 expression can increase PI3K/Akt and NF-κB activity and decrease apoptosis of gastric cancer cells treated with celastrol, which could be reversed by PI3K inhibitor.

CONCLUSIONS

Our data revealed that the effect of celastrol on apoptosis was due to miR-21 inhibiting the PI3K/Akt-dependent NF-κB pathway.

miR-106a confers cisplatin resistance by regulating PTEN/Akt pathway in gastric cancer cells

Recent studies have shown that microRNA-106a (miR-106a) is overexpressed in gastric cancer and contributes to tumor growth. In this study, we investigated whether miR-106a mediated resistance of the gastric cancer cell line SGC7901 to the chemotherapeutic agent cisplatin (DDP). MiR-106a expression was up-regulated in the DDP resistant cell line SGC7901/DDP compared with its parental line SGC7901. Transfection of miR-106a induced DDP resistance in SGC7901, while suppression of miR-106a in SGC7901/DDP led to enhanced DDP cytotoxicity. Further study indicated that the mechanism of miR-106a-induced DDP resistance involved the expression of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) protein and its downstream phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway. This study provides a novel mechanism of DDP resistance in gastric cancer.

The advance of application for microRNAs in cancer gene therapy

MicroRNAs (miRNAs, miRs) are closely associated with biological processes of tumor cells as the key regulators by recognizing specific mRNA targets, and further mediating post-transcriptional inhibition of tumor related genes. Therefore, miRNAs may be used as optional therapeutic targets in tumors resulting from accumulation of multiple gene mutations and their interactions. Currently, there are many researches for making miRNAs safely and efficiently be applied in cancer gene therapy (CGT). This review summarizes miRNA anomalous biogenesis pathway, different roles in disease processes of tumors, by which it further clarifies miRNA implemented methods including the combined treatment related with miRNA in CGT; simultaneously, briefly illustrates the delivery systems of miRNA.

Study of oxidative stress in human lens epithelial cells exposed to 1.8 GHz radiofrequency fields

Objectives

The aims of the present study were to determine oxidative stress and to explore possible reasons of reactive oxygen species (ROS) increase in human lens epithelial (HLE) B3 cells exposed to low intensity 1.8 GHz radiofrequency fields (RF).

Methods

The HLE B3 cells were divided into RF exposure and RF sham-exposure groups. The RF exposure intensity was at specific absorption rate (SAR) of 2, 3, or 4 W/kg. The ROS levels were measured by a fluorescent probe 2′7′-dichlorofluorescin diacetate (DCFH-DA) assay in the HLE B3 cells exposed to 1.8 GHz RF for 0.5, 1, and 1.5 h. Lipid peroxidation and cellular viability were detected by an MDA test and Cell Counting Kit-8 (CCK-8) assays, respectively, in the HLE B3 cells exposed to 1.8 GHz RF for 6, 12, and 24 h, respectively. The mRNA expression of SOD1, SOD2, CAT, and GPx1 genes and the expression of SOD1, SOD2, CAT, and GPx1 proteins was measured by qRT-PCR and Western blot assays in the HLE B3 cells exposed to 1.8 GHz RF for 1 h.

Results

The ROS and MDA levels significantly increased (P<0.05) in the RF exposure group and that the cellular viability, mRNA expression of four genes, and expression of four proteins significantly decreased (P<0.05) compared with the RF sham-exposure group.

Conclusions

Oxidative stress is present in HLE B3 cells exposed to 1.8 GHz low-intensity RF and that the increased production of ROS may be related to down-regulation of four antioxidant enzyme genes induced by RF exposure.