Lentivirus-mediated overexpression of miR-124 suppresses growth and invasion by targeting JAG1 and EZH2 in gastric cancer

Tumor- and metastasis-promoting roles of miR-488 inhibition via HULC enhancement and EZH2-mediated p53 repression in gastric cancer

Dysregulation of microRNAs (miRNAs or miRs) is implicated in the development of gastric cancer (GC), which is possibly related to their roles in targeting tumor-suppressive or tumor-promoting genes. Herein, the current study was intended to ascertain the function of miR-488 and its modulatory mechanism in GC. Initially, human GC cells were assayed for their in vitro malignancy after miRNA gain- or loss-of-function and RNA interference or overexpression. Also, tumorigenesis and liver metastasis were evaluated in nude mouse models. Results demonstrated that miR-488 elevation suppressed GC (MKN-45 and OCUM-1) cell proliferation, migration, and invasiveness in vitro and reduced their tumorigenesis and liver metastasis in vivo. The luciferase assay identified that miR-488 bound to HULC and inhibited its expression. Furthermore, HULC could enhance EZH2-H3K27me3 enrichment at the p53 promoter region and epigenetically repress the p53 expression based on the data from RIP- and ChIP-qPCR assay. Additionally, HULC was validated to enhance GC growth and metastasis in vitro and in vivo. Overall, HULC re-expression elicited by miR-488 inhibition can enhance EZH2-H3K27me3 enrichment in the p53 promoter and repress the p53 expression, thus promoting the growth and metastasis of GC.

The long and short non-coding RNAs modulating EZH2 signaling in cancer

Non-coding RNAs (ncRNAs) are a large family of RNA molecules with no capability in encoding proteins. However, they participate in developmental and biological processes and their abnormal expression affects cancer progression. These RNA molecules can function as upstream mediators of different signaling pathways and enhancer of zeste homolog 2 (EZH2) is among them. Briefly, EZH2 belongs to PRCs family and can exert functional roles in cells due to its methyltransferase activity. EZH2 affects gene expression via inducing H3K27me3. In the present review, our aim is to provide a mechanistic discussion of ncRNAs role in regulating EZH2 expression in different cancers. MiRNAs can dually induce/inhibit EZH2 in cancer cells to affect downstream targets such as Wnt, STAT3 and EMT. Furthermore, miRNAs can regulate therapy response of cancer cells via affecting EZH2 signaling. It is noteworthy that EZH2 can reduce miRNA expression by binding to promoter and exerting its methyltransferase activity. Small-interfering RNA (siRNA) and short-hairpin RNA (shRNA) are synthetic, short ncRNAs capable of reducing EZH2 expression and suppressing cancer progression. LncRNAs mainly regulate EZH2 expression via targeting miRNAs. Furthermore, lncRNAs induce EZH2 by modulating miRNA expression. Circular RNAs (CircRNAs), like lncRNAs, affect EZH2 expression via targeting miRNAs. These areas are discussed in the present review with a focus on molecular pathways leading to clinical translation.

Tumor Suppressive Effects of miR-124 and Its Function in Neuronal Development

MicroRNA-124 (miR-124) is strongly expressed in neurons, and its expression increases as neurons mature. Through DNA methylation in the miR-124 promoter region and adsorption of miR-124 by non-coding RNAs, miR-124 expression is known to be reduced in many cancer cells, especially with high malignancy. Recently, numerous studies have focused on miR-124 due to its promising tumor-suppressive effects; however, the overview of their results is unclear. We surveyed the tumor-suppressive effect of miR-124 in glial cell lineage cancers, which are the most frequently reported cancer types involving miR-124, and in lung, colon, liver, stomach, and breast cancers, which are the top five causes of cancer death. Reportedly, miR-124 not only inhibits proliferation and accelerates apoptosis, but also comprehensively suppresses tumor malignant transformation. Moreover, we found that miR-124 exerts its anti-tumor effects by regulating a wide range of target genes, most notably STAT3 and EZH2. In addition, when compared to the original role of miR-124 in neuronal development, we found that the miR-124 target genes that contribute to neuronal maturation share similarities with genes that cause cancer cell metastasis and epithelial-mesenchymal transition. We believe that the two apparently unrelated fields, cancer and neuronal development, can bring new discoveries to each other through the study of miR-124.

MiR-124-5p Inhibits the Progression of Gastric Cancer by Targeting MIEN1

Objective:

To observe the effect of miR-124-5p on progression of gastric cancer (GC) and explore the targeting mechanism.

Methods:

After collecting the specimens, we used real-time fluorescence quantitative PCR to detect the miR-124-5p level of GC tissue and corresponding adjacent tissue. Then MTT test and scratch wound-healing assay were hired to evaluate the influence of miR-124-5p in GC cell (SGC-803 and SGC7901) migration and proliferation ability. The binding of miR-124-5p to migration and invasion enhancer 1 (MIEN1) was detected through dual luciferase reporter gene experiment and western blot was utilized to assay the protein level of MIEN1.

Results:

Compared with adjacent tissues, miR-124-5p level in GC tissues was lower significantly. MiR-124-5p mimic inhibited the metastasis and proliferation ability of SGC7901 cells and miR-124-5p inhibitor promoted the migration and proliferation ability of SGC803 cells. In addition, miR-124-5p targeted MIEN1 and negatively modulated the MIEN1 expression in SGC-803 and SGC7901 cells. Silencing MIEN1 negatively regulated the metastasis and proliferation ability of SGC7901 cells.

Conclusion:

MiR-124-5p inhibited the GC cell proliferation and metastasis phenotypes through MIEN1, which probably becomes a novel molecular target for clinical GC treatment.

Targeting Notch in oncology: the path forward

Notch signalling is involved in many aspects of cancer biology, including angiogenesis, tumour immunity and the maintenance of cancer stem-like cells. In addition, Notch can function as an oncogene and a tumour suppressor in different cancers and in different cell populations within the same tumour. Despite promising preclinical results and early-phase clinical trials, the goal of developing safe, effective, tumour-selective Notch-targeting agents for clinical use remains elusive. However, our continually improving understanding of Notch signalling in specific cancers, individual cancer cases and different cell populations, as well as crosstalk between pathways, is aiding the discovery and development of novel investigational Notch-targeted therapeutics.

MiR-124 sensitizes cisplatin-induced cytotoxicity against CD133+ hepatocellular carcinoma cells by targeting SIRT1/ROS/JNK pathway

Drug resistance is still a major obstacle for efficient treatment of hepatocellular carcinoma (HCC) during the cisplatin-based chemotherapy. Recent studies have demonstrated that CD133 positive population of cancer cells are responsible for multiple drug resistance. We are supposed to take strategies to sensitize CD133⁺ HCC cells to cisplatin treatment. In the present study, CD133⁺ HCC cells showed significant cisplatin-resistance compared to the CD133^- HCC cells. Downregulation of miR-124 was observed in CD133⁺ HCC cells. However, enforced expression of miR-124 can increase the sensitivity of CD133⁺ HCC cells to cisplatin treatment in vitro and in vivo. Mechanically, overexpression of miR-124 was found to inhibit the expression of SIRT1 and thus promoted the generation of ROS and phosphorylation of JNK. As the results, overexpression of miR-124 expanded the apoptosis in cisplatin-treated CD133⁺ HCC cells. We then demonstrated that overexpression of miR-124 sensitized cisplatin-induced cytotoxicity against CD133⁺ hepatocellular carcinoma cells by targeting SIRT1/ROS/JNK pathway.

Targeting EZH2 as a novel therapeutic strategy for sorafenib-resistant thyroid carcinoma

Thyroid carcinoma is the most common endocrine malignancy. Surgery, post‐operative selective iodine‐131 and thyroid hormone suppression were the most common methods for the therapy of thyroid carcinoma. Although most patients with differentiated thyroid carcinoma (DTC) showed positive response for these therapeutic methods, some patients still have to face the radioactive iodine (RAI)‐refractory problems. Sorafenib is an oral multikinase inhibitor for patients with advanced RAI refractory DTC. However, the side effects and drug resistance of sorafenib suggest us to develop novel drugs and strategies for the therapy of thyroid carcinoma. In this study, we firstly found that patients with sorafenib resistance showed no significant change in rapidly accelerated fibrosarcoma and VEGFR expression levels compared with sorafenib sensitive patients. Moreover, a further miRNAs screen by qRT‐PCR indicated that miR‐124‐3p and miR‐506‐3p (miR‐124/506) were remarkably reduced in sorafenib insensitive patients. With a bioinformatics prediction and functional assay validation, we revealed that enhancer of zeste homolog 2 (EZH2) was the direct target for miR‐124/506. Interestingly, we finally proved that the sorafenib resistant cells regained sensitivity for sorafenib by EZH2 intervention with miR‐124/506 overexpression or EZH2 inhibitor treatment in vitro and in vivo, which will lead to the decreased tri‐methylation at lysine 27 of histone H3 (H3K27me3) and increased acetylated lysine 27 of histone H3 (H3K27ac) levels. Therefore, we conclude that the suppression of EZH2 represents a potential target for thyroid carcinoma therapy.

Expression of miR-124 in gastric adenocarcinoma and the effect on proliferation and invasion of gastric adenocarcinoma SCG-7901 cells

Expression of miR-124 in gastric adenocarcinoma cell line SGC-7901 and its effect on biological functions was investigated. Expression of miR-124 in cancer tissues and paracancerous tissues of gastric adenocarcinoma patients was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). RT-qPCR was used to detect the expression of miR-124 in human normal gastric epithelial cells GES-1 and gastric adenocarcinoma SGC-7901 cells. Cells in miR-124 group were transfected with miR-124 agomir, cells in NC group were transfected with agomir-negative control sequence and cells in the control group were not transfected. MTT assay was used to detect cell proliferation, and Transwell invasion assay to detect cell invasion ability, and the effect of transfected miR-124 agonist on the proliferation and invasive ability of gastric adenocarcinoma cells was evaluated. RT-qPCR results showed that miR-124 expression was significantly downregulated in gastric adenocarcinoma tumor tissues compared with paracancerous tissues. Compared with cells of normal human gastric epithelial cell line GES-1, the expression of miR-124 human gastric adenocarcinoma SGC-7901 cells was significantly downregulated. At 12 h, there was no significant difference in OD at 490 nm in the three groups (P>0.05). OD (490) in the three groups showed a gradual upward trend. After transfection, proliferation curves of the three groups showed an upward trend, proliferation rate of miR-124 group was significantly lower than that of NC and control groups (P<0.05). The number of invading cells in miR-124 group was significantly lower than that in NC group and control group, but there was no significant difference in the number of cell invasion between the NC and control groups. miR-124 can inhibit the proliferation and invasion of gastric adenocarcinoma cells. Downregulation of miR-124 expression in gastric adenocarcinoma may be closely related to the development of gastric adenocarcinoma.