Tumor-suppressive MEG3 induces microRNA-493-5p expression to reduce arabinocytosine chemoresistance of acute myeloid leukemia cells by downregulating the METTL3/MYC axis.

BACKGROUND: Chemoresistance serves as a huge obstacle for acute myeloid leukemia (AML) patients. To counteract the chemoresistance in AML cells, we discussed the role of maternally expressed gene 3 (MEG3) in arabinocytosine (AraC) chemoresistance in AML cells. METHODS: MEG3, microRNA (miR)-493-5p, methyltransferase-like 3 (METTL3) and MYC expression in AML cells was determined and then their interactions were also analyzed. Then, the viability and apoptosis of AML cells were determined through loss- and gain- function assay. The level of m6A modification in AML cells was examined. AML mouse models were also established to validate the potential roles of MEG3. RESULTS: MEG3 and miR-493-5p were downregulated in AML cells, and they were lower in resistant cells than in parental cells. MEG3 led to elevated expression of miR-493-5p which targeted METTL3. METTL3 increased expression of MYC by promoting its m6A levels. Overexpression of MEG3 and miR-493-5p or knockdown of METTL3 inhibited HL-60 and Molm13 cell proliferation and promoted their apoptosis. Overexpressed MEG3 induced heightened sensitivity of AML cells to AraC. However, the suppression of miR-493-5p reversed the effects of overexpressed MEG3 on AML cells. CONCLUSIONS: Collectively, MEG3 could upregulate miR-493-5p expression and suppress the METTL3/MYC axis through MYC m6A methylation, by which MEG3 promoted the chemosensitivity of AML cells.

Lung cancer­associated transcript 1 facilitates tumorigenesis in laryngeal squamous cell carcinoma through the targeted inhibition of miR­493.

Long non­coding RNAs (lncRNAs) serve important roles in the tumorigenesis of a diverse range of cancer types. The lung cancer­associated transcript 1 (LUCAT1), has been reported to promote the proliferation, migration and invasion of oral squamous cell carcinoma cells. However, the exact role of LUCAT1 in laryngeal squamous cell carcinoma (LSCC) remains to fully understood. The present study aimed to interrogate the role and modulatory mechanism of LUCAT1 in LSCC. Reverse transcription­quantitative PCR and western blotting were used to investigate the expression of LUCAT1 and miR­493, as well as the protein expression of cyclin­dependent kinase 2, cyclin E1, p21, matrix metalloproteinase (MMP)2, MMP9, vascular endothelial growth factor­C, Bcl­2, Bax, cleaved caspase­3 and procaspase­3. Cell Counting Kit­8, flow cytometry, wound healing and Transwell assays were performed to analyze the proliferation, cell cycle, apoptosis levels, and the migratory and invasive abilities, respectively, of the LSCC AMC­HN­8 cell line. In addition, dual­luciferase reporter and ribonucleoprotein immunoprecipitation assays were used to investigate the binding between LUCAT1 and microRNA (miR)­493. The results of the present study revealed that the expression levels of LUCAT1 were upregulated in AMC­HN­8 cells. The genetic knockdown of LUCAT1 expression levels significantly suppressed the cell proliferation, alongside downregulating the expression levels of CDK2 and cyclin E1 and upregulating p21 expression levels. In addition, the knockdown of LUCAT1 inhibited cell migration and invasion, as demonstrated using the wound healing and Transwell assays, respectively. Moreover, LUCAT1 knockdown promoted cell apoptosis and upregulated the expression levels of Bax and cleaved caspase­3, whilst downregulating the expression levels of Bcl­2. Furthermore, LUCAT1 was discovered to directly bind to and inhibit the well­known tumor suppressor, miR­493. Notably, the specific inhibition of miR­493 partly blocked the anticancer effects of LUCAT1 knockdown in AMC­HN­8 cells. In conclusion, these results suggested that LUCAT1 may facilitate tumorigenesis in LSCC through the targeted inhibition of miR­493, which provides evidence for a novel target for the treatment of LSCC.

Long Non-Coding RNA LUCAT1 Promotes Progression of Thyroid Carcinoma by Reinforcing ADAM10 Expression Through Sequestering microRNA-493.

BACKGROUND: Long non-coding RNA (lncRNA) LUCAT1 has recently been recognized as an oncogene in several malignancies. This study was launched to probe its role in thyroid carcinoma (TC) development and the implicated molecules. METHODS: LUCAT1 expression in TC cell lines and in normal thyroid follicular epithelial cell line Nthy-ori3-1 was determined by RT-qPCR. Binding relationships between LUCAT1 and microRNA (miR)-493, and between miR-493 and a disintegrin and metalloproteinase-10 (ADAM10) were predicted on a bioinformatics system and then validated through luciferase reporter gene assays. Expression of miR-493 and ADAM10 in TC cells was determined. Gain- and loss-of functions of LUCAT1, miR-493 and ADAM10 were performed to explore their influences on the behaviors of TC cells. Xenograft tumors were induced in nude mice for in vivo studies. RESULTS: LUCAT1 and ADAM10 were highly expressed, while miR-493 was poorly expressed in TC cell lines. LUCAT1 served as a miR-493 sponge to upregulate ADAM10 expression. Silencing of LUCAT1 discouraged proliferation, invasion, and migration but triggered apoptosis of TC cells. By contrast, these changes were abrogated by further miR-493 inhibition or ADAM10 upregulation. The in vitro experiment results were reproduced in vivo. In addition, miR-493 inhibition or ADAM10 overexpression was found to increase the phosphorylation of STAT3 in cells. CONCLUSION: This study evidenced that LUCAT1 increases ADAM10 expression through sequestering miR-493, leading to JAK-STAT activation and TC cell growth and metastasis. LUCAT1 and ADAM10 may serve as therapeutic targets for TC treatment.

Long noncoding RNA NR2F1-AS1 promotes the malignancy of non-small cell lung cancer via sponging microRNA-493-5p and thereby increasing ITGB1 expression.

Several studies have reported that the long noncoding ribonucleic acid (lncRNA) NR2F1 antisense RNA 1 (NR2F1-AS1) affects multiple cellular pathways that are involved in tumorigenesis and tumor progression. The present study aimed to detect NR2F1-AS1 expression in non-small cell lung cancer (NSCLC), investigate the role of NR2F1-AS1 in promoting the tumorigenic behavior of NSCLC cells, and elucidate the mechanism underlying the effect of NR2F1-AS1 on NSCLC progression. Our results showed that NR2F1-AS1 expression was upregulated in NSCLC cells, and notably, its upregulation was correlated with adverse clinical characteristics and shorter overall survival in patients with NSCLC. The absence of NR2F1-AS1 functionally decreased NSCLC cell proliferation, migration, and invasion and promoted tumor cell apoptosis. In addition, the tumor growth of NSCLC cells in vivo was inhibited after NR2F1-AS1 silencing. Mechanistically, NR2F1-AS1 functioned as a competing endogenous RNA for miR-493-5p and consequently increased ITGB1 expression. Rescue assays further validated that an increased output of the miR-493-5p/ITGB1 axis could neutralize the regulatory impact of NR2F1-AS1 knockdown on the malignant phenotype of NSCLC cells. In summary, the NR2F1-AS1/miR-493-5p/ITGB1 pathway initiates pro-oncogenic behavior in NSCLC tumor progression, and the NR2F1-AS1/miR-493-5p/ITGB1 axis may provide new molecular targets for anticancer therapy against NSCLC.

Long noncoding RNA GAS6-AS2 sponges microRNA-493, thereby enhancing the malignant characteristics of breast cancer cells via upregulation of FUT4.

Long noncoding RNA (lncRNA) GAS6-AS2 serves as an oncogenic lncRNA in various types of human cancer. In this study, we attempted to examine the functions of GAS6-AS2 in breast cancer (BC) and explore the potential mechanisms involved. Reverse-transcription quantitative PCR was carried out to determine GAS6-AS2 expression in BC tissues and cell lines. Multiple functional experiments, including a Cell Counting Kit-8 assay, Transwell migration and invasion assays, and an in vivo nude-mouse xenograft experiment, were conducted to evaluate the effects of GAS6-AS2 in BC cells. GAS6-AS2 expression was high in BC tumors, manifesting a strong correlation with tumor size, lymph node metastasis, TNM stage, and shorter overall survival in patients with BC. A knockdown of GAS6-AS2 restricted BC cell proliferation, migration, and invasion in vitro and retarded tumor growth in vivo. With regard to its mechanism, GAS6-AS2 acted as a competing endogenous RNA that sponged microRNA-493 (miR-493), thereby increasing the expression of fucosyltransferase IV (FUT4). Either miR-493 inhibition or FUT4 upregulation abrogated the consequences of GAS6-AS2 knockdown in BC cells. These results revealed that GAS6-AS2 sponges miR-493 to enhance the malignant characteristics of BC in vitro and in vivo by increasing FUT4 expression. Thus, this lncRNA is an effective therapeutic target in BC and a promising diagnostic biomarker of this cancer.

microRNA-493 inhibits tongue squamous cell carcinoma oncogenicity via directly targeting HMGA2.

BACKGROUNDS: microRNA-493-3p (miR-493) has been reported to be critically downregulated in multiple types of human cancer. However, the expression level, biological roles and underlying mechanism of miR­493 in tongue squamous cell carcinoma (TSCC) remain to be elucidated. METHODS: RT-qPCR was utilized for the determination of miR-493 expression in TSCC tissues and cell lines. The influence of miR-493 overexpression on TSCC cell proliferation, apoptosis, migration, invasion in vitro and tumor growth in vivo were explored via MTT assay, flow cytometry analysis, cell migration and invasion assays, and xenograft tumors in nude mice, respectively. Bioinformatics analysis, luciferase reporter assays, RT-qPCR and Western blotting were performed to clarify the potential mechanisms involved in the action of miR-493 in TSCC cells. RESULTS: miR-493 was significantly downregulated in TSCC tissues and cell lines. Decreased miR-493 expression was notably correlated with tumor differentiation, depth of invasion and TNM stage. Additionally, patients with TSCC having low miR-493 expression showed lower overall survival rate. Functionally, miR-493 upregulation inhibited TSCC cell proliferation, migration, invasion in vitro; induced cell apoptosis; and decreased the tumor growth in vivo. Bioinformatics analysis followed by luciferase reporter assays also demonstrated that miR-493 directly bound to the 3'-untranslated region of high-mobility group AT-hook 2 (HMGA2) in TSCC cells, and therefore reduced HMGA2 expression at the mRNA and protein level. Furthermore, HMGA2 was overexpressed in TSCC tissues and inversely correlated with miR-493. Moreover, silenced HMGA2 expression simulated the tumor-suppressing roles of miR-493 overexpression on TSCC cells. HMGA2 overexpression eliminated the inhibitory roles of miR-493 overexpression on TSCC cells. CONCLUSION: These observations demonstrated that miR-493 is a tumor suppressor inhibited the oncogenicity of TSCC cells by directly targeting HMGA2. These results provide sufficient evidence for the miR-493/HMGA2 axis as a novel therapeutic target for the treatment of patients with TSCC in the future.

MicroRNA-493-5p inhibits proliferation and metastasis of osteosarcoma cells by targeting Kruppel-like factor 5.

Osteosarcoma, including spinal osteosarcoma, has properties of high degree of malignancy, high rate of recurrence, and high incidence of metastasis. microRNAs can exert oncogenic or tumor suppressive roles in cancer cells. This study explored the effects of microRNA-493-5p (miR-493-5p) on osteosarcoma cell viability, migration, invasion, and apoptosis, as well as the underlying possible mechanism. First, the expression of miR-493-5p in osteosarcoma tissues and cells was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Then, the effects of miR-493-5p overexpression (or suppression) on osteosarcoma cell viability, migration, invasion, and apoptosis, as well as Kruppel-like factor 5 (KLF5) expression, were assessed using the Cell Counting Kit-8 assay, two-chamber transwell assay, Annexin V-FITC/PI apoptosis detection kit, qRT-PCR, and western blotting, respectively. Finally, the roles of KLF5 in miR-493-5p suppression-induced U20S cell viability, migration, and invasion enhancement, as well as the PI3K/AKT pathway activation, were evaluated. We found that miR-493-5p had lower expression in tumor tissues of spinal osteosarcoma and osteosarcoma cells. Overexpression of miR-493-5p inhibited osteosarcoma U20S cell viability, migration, and invasion, but induced cell apoptosis. On the contrary, suppression of miR-493-5p-promoted U20S cell viability, migration, and invasion. KLF5 was a direct target gene of miR-493-5p, which participated in the effects of miR-493-5p on U20S cell viability, migration, invasion, and apoptosis. Furthermore, suppression of the miR-493-5p activated PI3K/AKT pathway in U20S cells by upregulating KLF5. In conclusion, we revealed that miR-493-5p exerted tumor suppressive roles in spinal osteosarcoma and osteosarcoma cells. Overexpression of miR-493-5p inhibited proliferation and metastasis of osteosarcoma cells by downregulating KLF5 and inactivating the PI3K/AKT signaling pathway.

MicroRNA-493 inhibits the proliferation and invasion of osteosarcoma cells through directly targeting specificity protein 1.

Osteosarcoma (OS) is the most common type of primary bone tumor and accounts for ~60% of all malignant bone tumors in children and adolescents. A large number of studies have proposed that the dysregulated and dysfunctional microRNAs may serve important roles in the occurrence, progression and metastasis of various types of human cancer, including OS. MicroRNA-493 (miR-493) has been identified to act as a tumor suppressor in several types of human cancer. However, little is known regarding the expression pattern and clinical significance of miR-493 in OS. In the present study, reverse transcription-quantitative polymerase chain reaction analysis revealed that miR-493 was markedly downregulated in OS tissues and cell lines and a low miR-493 level were associated with distant metastasis and clinical stage. Furthermore, functional experiments demonstrated that enforced expression of miR-493 led to a significant decrease in OS cell proliferation and invasion in vitro. Furthermore, through bioinformatics analysis, specificity protein 1 (SP1) was identified as a direct target gene of miR-493 in OS. Its expression was upregulated in OS tissues and was negatively associated with miR-493 expression levels. Inhibition of SP1 expression also suppressed the proliferation and invasion of OS, exerting a similar effect to that induced by miR-493 overexpression. These results suggested that miR-493 inhibited OS cell proliferation and invasion through negative regulation of SP1. Therefore, miR-493/SP1 may represent a potential therapeutic target for the treatment of OS.

MicroRNA-493 is a prognostic factor in triple-negative breast cancer.

Breast cancer is one of the most common malignant diseases in women. Triple-negative breast cancer (TNBC) shows higher aggressiveness and recurrence rates than other subtypes, and there are no effective targets or tailored treatments for TNBC patients. Thus, finding effective prognostic markers for TNBC could help clinicians in their ability to care for their patients. We used tissue microarrays (TMAs) to detect microRNA-493 (miR-493) expression in breast cancer samples. A miRCURY LNA detection probe specific for miR-493 was used in in situ hybridization assays. Staining results were reviewed by two independent pathologists and classified as high or low expression of miR-493. Kaplan-Meier survival plots and multivariate Cox analysis were carried out to clarify the relationship between miR-493 and survival. In the Kaplan-Meier analysis, patients with high miR-493 expression had better disease-free survival than patients with low miR-493 expression. After adjusting for common clinicopathological factors in breast cancer, the expression level of miR-493 was still a significant prognostic factor in breast cancer. Further subtype analysis revealed that miR-493 expression levels were only significantly prognostic in TNBC patients. These results were validated in the Molecular Taxonomy of Breast Cancer International Consortium database for overall survival. We proved the prognostic role of miR-493 in TNBC by using one of the largest breast cancer TMAs available and validated it in a large public RNA sequencing database.

miR-493 inhibits proliferation and invasion in pancreatic cancer cells and inversely regulated hERG1 expression.

The human ether-a-go-go-related potassium channel 1 (hERG1) is a component of the voltage-gated Kv11.1 potassium channel, which has been recently indicated to have a crucial role in the tumorigenesis of multiple tumors, including pancreatic carcinoma. Pancreatic carcinoma is one of the most malignant human cancer types, which has an extremely poor prognosis. The present study demonstrated that the expression levels of hERG1 were markedly elevated in pancreatic cancer tissues and pancreatic cancer cell lines, and that the abnormal hERG1 expression was significantly associated with the proliferation and invasion ability of pancreatic cancer. Furthermore, hERG1 was identified to be a direct target of miR-493, which is generally reduced in pancreatic cancer tissues and cell lines. These findings provide a novel insight into the regulatory mechanism of miR-493/hERG1 in pancreatic cancer cell proliferation and invasion, which may aid the development of novel diagnostic and therapeutic strategies for pancreatic cancer in the future.