Reduced expression of microRNA-134 correlates with malignancy and poor prognosis in human glioma

LINC00470 promotes tumour proliferation and invasion, and attenuates chemosensitivity through the LINC00470/miR-134/Myc/ABCC1 axis in glioma

Glioma is the most common primary malignant tumour in the brain; temozolomide (TMZ) is the most prevalent chemotherapeutic drug currently used to combat this cancer. We reported previously that the long intergenic non‐protein coding RNA 470 (LINC00470) is a novel prognostic biomarker for glioma and promotes the tumour growth in an intracranial transplantation mouse model. However, the effects of LINC00470 on glioma cell proliferation, invasion and TMZ chemosensitivity, as well as its molecular mechanism, remain unclear. In this study, we found elevated expression levels of LINC00470 and MYC in glioma tissues and cells and decreased expression of microRNA‐134 (miR‐134). Functional studies have shown that LINC00470 promotes proliferation and invasion, and attenuates chemosensitivity of glioma cells, while miR‐134 exerts the opposite effect. In the rescue experiments, the tumorigenic effect of LINC00470 was offset by miR‐134. In the mechanism study, we found that LINC00470 was a competitive endogenous RNA (ceRNA) of miR‐134 and that miR‐134 can directly target MYC and negatively regulate its expression. Furthermore, MYC was positively correlated with ATP‐binding cassette subfamily C member 1 (ABCC1) expression in glioma cells and MYC up‐regulated ABCC1 expression. Further studies found that LINC00470 regulated MYC by sponging miR‐134 to regulate the expression of ABCC1. We concluded that LINC00470 promoted the expression of MYC and ABCC1 by suppressing miR‐134, thus promoting glioma cell proliferation and invasion, and attenuating TMZ chemosensitivity. Moreover, the LINC00470/miR‐134/MYC/ABCC1 axis constitutes a potential therapeutic target.

CircZNF609/miR-134-5p/BTG-2 axis regulates proliferation and migration of glioma cell

Objectives

MicroRNAs are abundant in eukaryotic cells and play key roles in cancers. Circular RNAs (CircRNAs) served as the competing endogenous RNAs (ceRNAs) in mediating multiple cell processes. This study aims to define the role of CircRNA CircZNF609/miR-134-5p in glioma as well as the underlying regulating mechanism.

Methods

Relative expression of miR-134-5p, CircZNF609 and BTG-2 mRNA was determined by quantitative real-time PCR. Cell proliferation was analysed by CCK-8 assay. Cell migration was assessed by cell wound scratch assay. The direct regulatory of miR-134-5p on BTG-2 and CircZNF609 was verified by luciferase report gene assay.

Key findings

MiR-134-5p was significantly upregulated in glioma cells. The overexpression of miR-134-5p inhibited cell proliferation and migration of glioma cell U251 and U87. Reversely, knock-down of miR-134-5p enhanced cell proliferation and migration. Both BTG-2 and CircZNF609 are the direct targets of miR-134-5p, and their expression could be negatively regulated by miR-134-5p. CircZNF609 was significantly upregulated in U251 and U87 cells and acted as an oncogene to promote cell proliferation and cell migration of glioma cell U251 and U87.

Conclusions

These data proved that CircZNF609 served as a competing RNA to bind miR-134-5p that promoted BTG-2 expression leading to reduced proliferation and migration of glioma cell.

Diallyl disulfide suppresses FOXM1-mediated proliferation and invasion in osteosarcoma by upregulating miR-134

Diallyl disulfide (DADS), a volatile component of garlic oil, exerts anticancer activity in various types of cancers, while its anticancer effects against osteosarcoma (OS) have not been previously explored. This study aimed to investigate the anticancer potential of DADS in OS and to explore the underlying mechanisms. DADS reduced the cell viability and increased the expression of miR-134 in OS cell lines, and this effect was in a time- and concentration-dependent manner. Furthermore, in vitro functional assays revealed that DADS significantly inhibited the proliferation and invasion of human OS U2OS and MG-63 cells, which was partially reversed by miR-134 inhibitor transfection. DADS exhibited in vivo antitumor activity and upregulated miR-134 expression in xenograft tumors. Downregulation of miR-134 attenuated DADS-induced antitumor capacity. Further bioinformatics prediction analysis revealed that the 3'-untranslated region (3'-UTR) of Forkhead Box M1 (FOXM1) harbored miR-134-binding sites, and overexpression of miR-134 repressed the luciferase activity of the reporting vector containing FOXM1 3'-UTR. Both miR-134 overexpression and DADS inhibited FOXM1 expression in U2OS cells, while enforced expression of FOXM1 suppressed DADS-induced antiproliferation and anti-invasion capacity in U2OS cells. Furthermore, DADS treatment led to significant downregulation of cyclin D1, c-myc, and lymphoid enhancer-binding factor 1 expression, but the remarkably upregulated p21 level in U2OS cells. Collectively, DADS could be a promising anticancer agent for OS, and the underlying mechanisms might be associated with the antiproliferation and anti-invasion properties through upregulating miR-134 expression.

hsa_circ_0013958: a circular RNA and potential novel biomarker for lung adenocarcinoma

Circular RNAs (circRNAs) are associated with cancer progression and metastasis, although little is known about their role in lung adenocarcinoma (LAC). In the present study, microarrays were first used to screen for tumour-specific circRNA candidates in LAC tissue. Thirty-nine circRNAs were found to be up-regulated and 20 were down-regulated (fold change > 2.0). Among them, hsa_circ_0013958 was further confirmed to be up-regulated in all of the LAC tissues, cells and plasma. In addition, hsa_circ_0013958 levels were associated with TNM stage (P = 0.009) and lymphatic metastasis (P = 0.006). The area under the receiver operating characteristic curve was 0.815 (95% confidence interval = 0.727-0.903; P < 0.001). In addition, to further illustrate the bioactivities of hsa_circ_0013958 in LAC, siRNA-mediated inhibition of hsa_circ_0013958 was performed in vitro. The results showed that hsa_circ_0013958 promoted cell proliferation and invasion and inhibited cell apoptosis in LAC. Moreover, hsa_circ_0013958 was identified as a sponge of miR-134, and thus it up-regulated oncogenic cyclin D1, which plays a pivotal role in the development of non-small cell lung cancer. In conclusion, our results suggested that hsa_circ_0013958 could be used as a potential non-invasive biomarker for the early detection and screening of LAC.

miR-134: A Human Cancer Suppressor?

MicroRNAs (miRNAs) are small noncoding RNAs approximately 20-25 nt in length, which play crucial roles through directly binding to corresponding 3' UTR of targeted mRNAs. It has been reported that miRNAs are involved in numerous of diseases, including cancers. Recently, miR-134 has been identified to dysregulate in handles of human cancers, such as lung cancer, glioma, breast cancer, colorectal cancer, and so on. Increasing evidence indicates that miR-134 is essential for human carcinoma and participates in tumor cell proliferation, apoptosis, invasion and metastasis, drug resistance, as well as cancer diagnosis, treatment, and prognosis. Nevertheless, its roles in human cancer are still ambiguous, and its mechanisms are sophisticated as well, referring to a variety of targets and signal pathways, such as STAT5B, KRAS, MAPK/ERK signal pathway, Notch pathway, etc. Herein, we review the crucial roles of miR-134 in scores of human cancers via analyzing latest investigations, which might provide evidence for cancer diagnose, treatment, prognosis, or further investigations.

MicroRNA-134 modulates glioma cell U251 proliferation and invasion by targeting KRAS and suppressing the ERK pathway

Dysregulated microRNA-134 (miR-134) has been observed in glioma carcinogenesis, and studies suggested that the ERK pathway plays vital roles in glioma cell growth and proliferation. However, the fundamental relationship between miR-134 and the ERK pathway in glioma has not been fully explained. As a result, this study was aimed to explore the underlying functions of miR-134 in human glioma. Intentionally overexpressed or inhibited miR-134 expression resulted from the transfection of miR-134 mimics, or miR-134 inhibitor within glioma cell line U251 was detected using RT-PCR. Both cell counting kit-8 (CCK-8) assays and Transwell assays were carried out to clarify the proliferation and invasion of U251 cells transfected with miR-134 mimics or miR-134 inhibitors. Our findings showed that miR-134 was significantly downexpressed in glioma tissues, and low miR-134 expression was significantly related to high histopathological grades. However, upregulated miR-134 expression restrained the proliferation and invasion of U251 cells in vitro. Kirsten rat sarcoma viral oncogene (KRAS), a vital factor for the ERK pathway, was directly targeted by miR-134 through its binding with the 3'-UTR of KRAS in glioma. Furthermore, KRAS expression exhibited a positive correlation with the activity of the ERK pathway. Overexpression of KRAS without 3'-UTR partly offsets the suppressive effect of miR-134 on glioma progression. Our data also indicated that miR-134 negatively modulated glioma progression and upregulated miR-134 triggered aberrant activation of the ERK pathway by targeting KRAS. Therefore, miR-134 might be considered as a benign therapeutic target of glioma.

Regulation of NANOG in cancer cells

As one of the key pluripotency transcription factors, NANOG plays a critical role in maintaining the self-renewal and pluripotency in normal embryonic stem cells. Recent data indicate that NANOG is expressed in a variety of cancers and its expression correlates with poor survival in cancer patients. Of interest, many studies suggest that NANOG enhances the defined characteristics of cancer stem cells and may thus function as an oncogene to promote carcinogenesis. Therefore, NANOG expression determines the cell fate not only in pluripotent cells but also in cancer cells. Although the regulation of NANOG in normal embryonic stem cells is reasonably well understood, the regulation of NANOG in cancer cells has only emerged recently. The current review provides a most updated summary on how NANOG expression is regulated during tumor development and progression.