Overexpression of microRNA-448 inhibits osteosarcoma cell proliferation and invasion through targeting of astrocyte elevated gene-1

Advances in the Biological Functions and Mechanisms of miRNAs in the Development of Osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumors, mainly occurring in children and adolescents, and is characterized by high morbidity and poor prognosis. MicroRNAs, a class of noncoding RNAs consisting of 19 to 25 nucleotides, are involved in cell proliferation, invasion, metastasis, and apoptosis to regulate the development and progression of osteosarcoma. Studies have found that microRNAs are closely related to the diagnosis, treatment, and prognosis of osteosarcoma patients and have an important role in improving drug resistance in osteosarcoma. This paper reviews the role of microRNAs in the pathogenesis of osteosarcoma and their clinical value, aiming to provide a new research direction for diagnosing and treating osteosarcoma and achieving a better prognosis.

Targeting Wnt/β-catenin signaling by microRNAs as a therapeutic approach in chemoresistant osteosarcoma

Osteosarcoma (OS) is an adolescent and young adult malignancy that mostly occurs in long bones. The treatment of OS is still a big challenge for clinicians due to increasing chemoresistance, and many efforts are being made today to find more beneficial treatments. In this regard, the use of microRNAs has shown a high capacity to develop promising therapies. By targeting cancer-involved signaling pathways, microRNAs reduce the cellular level of these protein pathways; thereby reducing the growth and invasion of tumors, and even leading cancer cells to apoptosis. One of these oncogenic pathways that play an important role in OS development and can be targeted by microRNAs is the Wnt/β-catenin signaling pathway. Hence, the first goal of this review article is to explain the cross-talk of microRNAs and the Wnt/β-catenin signaling in OS and then discussing recent findings of the use of microRNAs as a therapeutic approach in OS.

MicroRNA-448 targets SATB1 to reverse the cisplatin resistance in lung cancer via mediating Wnt/β-catenin signalling pathway

This study aims to examine whether miR-448 reverses the cisplatin (DDP) resistance in lung cancer by modulating SATB1. QRT-PCR and immunohistochemistry were used to examine the miR-448 and SATB1 expressions in DDP-sensitive and -resistant lung cancer patients. A microarray was used to investigate the cytoplasmic/nucleic ratio (C/N ratios) of genes in A549 cells targeted by miR-448, followed by Dual-luciferase reporter gene assay. A549/DDP cells were transfected with miR-448 mimics/inhibitors with or without SATB1 siRNA followed by MTT assay, Edu staining, flow cytometry, qRT-PCR and western blotting. MiR-448 was lower but SATB1 was increased in DDP-resistant patients and A549/DDP cells. And the patients showed low miR-448 expression or SATB1 positive expression had poor prognosis. SATB1, as a target gene with higher C/N ratios (>1), was found negatively regulated by miR-448. Besides, miR-448 inhibitors increased resistance index of A549/DDP cells, promoted cell proliferation, increased cell distribution in S phrase, declined cell apoptosis and activated Wnt/β-catenin pathway. However, SATB1 siRNA could reverse the above effect caused by miR-448 inhibitors. MiR-448 targeting SATB1 to counteract the DDP resistance of lung cancer cells via Wnt/β-catenin pathway.

MiR-448 targets BLC2 and inhibits the growth of pituitary adenoma cells

There is an increasing body of evidence indicating the important roles of miRNAs in the progression of pituitary adenoma. Recent studies have shown decreased expression and tumor suppressive function of miR-448 in cancers; however, the clinical significance of miR-448 in pituitary adenoma has remained largely unknown. In our study, we found that miR-448 was down-regulated in pituitary adenoma tissues and cell lines. Overexpression of miR-448 significantly inhibited the proliferation and migration of pituitary adenoma cells. Increased cell apoptosis was also observed with overexpression of miR-448. To further understand the mechanisms behind the regulation of pituitary adenoma by miR-448 in, the targets of miR-448 were predicted using the bioinformatics tools. B cell lymphoma 2 (BCL2) was identified as a target of miR-448. MiR-448 bound the 3'-untranslated region (UTR) of BCL2 and inhibited the expression of BCL2 in pituitary adenoma cells. There was a consistent and significantly negative correlation between the level of miR-448 and BCL2 in pituitary adenoma tissues. When BCL2 was highly expressed, the inhibitory impact of miR-448 on the proliferation and apoptosis of pituitary adenoma cells was significantly inhibited. Collectively, our findings emphasize the significance of the miR-448-BCL2 axis in the development of pituitary adenoma, highlighting the potential therapeutic significance of miR-448 in pituitary adenoma.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

MicroRNA-618 Directly Targets Metadherin mRNA To Suppress The Malignant Phenotype Of Osteosarcoma Cells By Reducing PTEN-AKT Pathway Output

Purpose

Dysregulation of microRNA-618 (miR-618) has been observed in multiple types of human cancer. However, whether miR-618 is implicated in osteosarcoma (OS) initiation and progression is still unclear. Hence, we measured the expression of miR-618 in OS tissues and cell lines. In addition, the roles of miR-618 and the mechanisms underlying its activities in OS cells were examined.

Methods

The expression status of miR-618 in OS was analyzed by reverse-transcription quantitative PCR. The regulatory roles of miR-618 overexpression in OS were explored by the Cell Counting Kit-8 assay, flow-cytometric analysis, Transwell cell migration and invasion assays, and a tumor xenograft experiment.

Results

The results revealed that the expression of miR-618 was notably lower in OS tissues and cell lines, and that the low miR-618 expression significantly correlated with the clinical stage and distant metastasis among patients with OS. Exogenous miR-618 expression significantly suppressed OS cell proliferation, migration, and invasion and induced apoptosis in vitro as well as slowed tumor growth in vivo. Mechanism investigation indicated that metadherin (MTDH) is a direct target gene of miR-618 in OS cells. A knockdown of MTDH mimicked the tumor-suppressive effects of miR-618 upregulation on OS cells. Notably, resumption of MTDH expression attenuated the miR-618–mediated reduction in OS cell growth and metastasis in vitro. In addition, miR-618 overexpression reduced the PTEN–AKT pathway output in OS cells both in vitro and in vivo through downregulation of MTDH.

Conclusion

To the best of our knowledge, this is the first study to show that miR-618 exerts crucial tumor-suppressive actions in OS pathogenesis by directly targeting MTDH mRNA and reducing PTEN–AKT pathway output. These results will help to elucidate the functions of miR-618 in OS and suggest that this miRNA may be investigated as a therapeutic target in this disease.

microRNA-564 inhibits the aggressive phenotypes of papillary thyroid cancer by directly targeting astrocyte-elevated gene-1

Background: Accumulating evidence has revealed that an increasing number of microRNAs (miRNAs) are dysregulated in papillary thyroid cancer (PTC) and that their dysregulation plays an important role in PTC onset and progression. Reportedly, miRNA-564 (miR-564) is downregulated in several types of human cancer. However, its expression profile and specific functions in PTC remain unclear to date. Methods: In this study, we used reverse transcription-quantitative polymerase chain reaction to detect miR-564 expression in PTC tissues and cell lines. Further, the regulatory roles of miR-564 in the malignant development of PTC in vitro and in vivo were examined using a series of functional experiments. In addition, the possible underlying mechanisms and signaling pathways involved were investigated. Results: We demonstrated that miR-564 expression markedly decreased in PTC tissues and cell lines, and this decrease correlated with the lymph node metastasis and tumor-node-metastasis stage. miR-564 upregulation significantly inhibited cell proliferation, migration, and invasion and induced cell apoptosis in vitro as well as hindered tumor growth in vivo. Furthermore, astrocyte-elevated gene-1 (AEG-1) was identified as a direct target gene of miR-564 in PTC cells. Its expression was upregulated and inversely correlated with miR-564 expression in clinically PTC tissues. Additionally, the silencing of AEG-1 expression could imitate the action of miR-564 overexpression in PTC cells. Remarkably, the restoration of AEG-1 expression partially abolished the tumor-suppressing effects induced by a miR-564 upregulation in PTC cells. Ectopic miR-564 expression deactivated the PTEN/Akt pathway in PTC cells in vitro and in vivo. Conclusion: Overall, the findings of the current study suggest that miR-564 is a tumor-suppressive miRNA that exerts crucial roles in the development and progression of PTC. Therefore, this miRNA might be a promising candidate target in the anticancer treatment of patients with PTC.

Effect of glycolysis inhibition by miR-448 on glioma radiosensitivity

OBJECTIVE

Although glucose metabolism reengineering is a typical feature of various tumors, including glioma, key regulators of glycolytic reprogramming are still poorly understood. The authors sought to investigate whether glycolysis inhibition by microRNA (miR)-448 increases radiosensitivity in glioma cells.

METHODS

The authors used glioma tissue samples from glioma patients, cells from glioblastoma (GBM) cell lines and normal human astrocyte cells, and subcutaneous tumor-bearing U87 cells in mice to examine the effects of signaling regulation by miR-448 in the response of glioma tissues and cells to radiation treatment. Techniques used for investigation included bioinformatics analyses, biochemical assays, luciferase reporter assays, and establishment of subcutaneous tumors in a mouse model. Glucose consumption, LDH activity, and cellular ATP were measured to determine the ability of glioma cells to perform glycolysis. Expression of HIF-1α was measured as a potential target gene of miR-448 in glycolysis.

RESULTS

miR-448 was detected and determined to be significantly downregulated in both glioma tissues from glioma patients and GBM cell lines. Furthermore, miR-448 acted as a tumor-inhibiting factor and suppressed glycolysis in glioma by negatively regulating the activity of HIF-1α signaling and then interfering with its downstream regulators relative to glycolysis, HK1, HK2, and LDHA. Interestingly, overexpression of miR-448 increased the x-radiation sensitivity of glioma cells. Finally, in in vivo experiments, subcutaneous tumor-bearing U87 cells in a mouse model verified that high expression of miR-448 also enhanced glioma radiosensitivity via inhibiting glycolytic factors.

CONCLUSIONS

miR-448 can promote radiosensitivity by inhibiting HIF-1α signaling and then negatively controlling the glycolysis process in glioma. A newly identified miR-448-HIF-1α axis acts as a potentially valuable therapeutic target that may be useful in overcoming radioresistance in glioma treatment.

MicroRNA-625-3p promotes the proliferation, migration and invasion of thyroid cancer cells by up-regulating astrocyte elevated gene 1

BACKGROUND

Thyroid cancer is the most common malignancy in human endocrine system. This study aimed to investigate the effects of microRNA-625-3p (miR-625-3p) on thyroid cancer cell proliferation, migration, invasion and apoptosis, as well as underlying potential mechanism.

METHODS

The relative expressions of miR-625-3p in tumor tissues and adjacent normal tissues of 20 patients with papillary thyroid cancer (PTC) were assessed using qRT-PCR. Cell transfection was used to up-regulate or down-regulate the expressions of miR-625-3p in thyroid cancer SW579 and TPC-1 cells. Effects of miR-625-3p overexpression or suppression on SW579 and TPC-1 cell viability, migration, invasion and apoptosis were detected respectively. The regulatory effect of miR-625-3p on astrocyte elevated gene 1 (AEG-1) expression was also analyzed. Then, the roles of AEG-1 in SW579 and TPC-1 cell proliferation, migration, invasion and apoptosis, as well as Wnt/β-catenin and c-Jun N-terminal kinase (JNK) pathways activation, were evaluated.

RESULTS

miR-625-3p had high expressions in tumor tissues, compared to adjacent normal tissues. Overexpression of miR-625-3p significantly promoted SW579 and TPC-1 cell proliferation, migration and invasion but had no influence on cell apoptosis. Knockdown of miR-625-3p had opposite effects, but induced cell apoptosis. AEG-1 was up-regulated by miR-625-3p overexpression and participated in the effects of miR-625-3p on SW-579 and TPC-1 cells. In addition, overexpression of AEG-1 induced the activation of Wnt/β-catenin and JNK pathways in SW579 and TPC-1 cells.

CONCLUSION

miR-625-3p promoted proliferation, migration and invasion of thyroid cancer cells by enhancing the expression of AEG-1 and activating downstream Wnt/β-catenin and JNK pathways.