MicroRNA-499a-5p inhibits osteosarcoma cell proliferation and differentiation by targeting protein phosphatase 1D through protein kinase B/glycogen synthase kinase 3β signaling

TMEM189 as a target gene of MiR-499a-5p regulates breast cancer progression through the ferroptosis pathway

MicroRNA (miR)-499a-5p has been reported to regulate the progression of various tumours. However, the role of miR-499a-5p in breast cancer is unclear. The purpose of this study was to investigate the role and mechanism of miR-499a-5p in breast cancer. The growth effect of miR-499a-5p on breast cancer cells was investigated by the CCK-8 assay, wound healing assay and Transwell invasion assay. The luciferase activity assay was used to verify the downstream targets of miR-499a-5p. The levels of GSH, MDA, and ROS were detected by kits. Quantitative real-time PCR and Western blot were used to determine the expression levels of TMEM189, COX-2, GPX4, and other related genes in cells. miR-499a-5p was down-regulated in MDA-MB-231 cells and was shown to reduced the viability, migration and invasion of MDA-MB-231 cells. Further studies revealed that TMEM189 is a target of miR-499a-5p. miR-499a-5p inhibited breast cancer cell growth by downregulating TMEM189. Furthermore, the down-regulation of TMEM189 promotes ferroptosis in breast cancer cells. The low expression of TMEM189 inhibited the development of breast cancer through the ferroptosis pathway. We have demonstrated for the first time that miR-499a-5p inhibits breast cancer progression by targeting the TMEM189-mediated ferroptosis pathway.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

Epi-miRNAs: Regulators of the Histone Modification Machinery in Human Cancer

Cancer is a leading cause of death and disability worldwide. Epigenetic deregulation is one of the most critical mechanisms in carcinogenesis and can be classified into effects on DNA methylation and histone modification. MicroRNAs are small noncoding RNAs involved in fine-tuning their target genes after transcription. Various microRNAs control the expression of histone modifiers and are involved in a variety of cancers. Therefore, overexpression or downregulation of microRNAs can alter cell fate and cause malignancies. In this review, we discuss the role of microRNAs in regulating the histone modification machinery in various cancers, with a focus on the histone-modifying enzymes such as acetylases, deacetylases, methyltransferases, demethylases, kinases, phosphatases, desumoylases, ubiquitinases, and deubiquitinases. Understanding of microRNA-related aberrations underlying histone modifiers in pathogenesis of different cancers can help identify novel therapeutic targets or early detection approaches that allow better management of patients or monitoring of treatment response.

Upregulation of miR-499a-5p Decreases Cerebral Ischemia/Reperfusion Injury by Targeting PDCD4

MiR-499a-5p was significantly downregulated in degenerative tissues and correlated with apoptosis. Nonetheless, the biological function of miR-499a-5p in acute ischemic stroke has been still unclear. In this study, we found that the plasma levels of miR-499a-5p were significantly downregulated in 64 ischemic stroke patients and negatively correlated with the National Institutes of Health Stroke Scale score. Then, we constructed cerebral ischemia/reperfusion (I/R) injury in rats after middle cerebral artery occlusion and subsequent reperfusion and oxygen-glucose deprivation and reoxygenation (OGD/R)-treated SH-SY5Y cell model. Transfection with miR-499a-5p mimic was accomplished by intracerebroventricular injection in the in vivo I/R injury model. We further found that miR-499a-5p overexpression decreased infarct volumes and cell apoptosis in the in vivo I/R stroke model using TTC and TUNEL staining. PDCD4 was a direct target of miR-499a-5p by luciferase report assay and Western blotting. Knockdown of PDCD4 reduced the infarct damage and cortical neuron apoptosis caused by I/R injury. MiR-499a-5p exerted neuroprotective roles mainly through inhibiting PDCD4-mediated apoptosis by CCK-8 assay, LDH release assay, and flow cytometry analysis. These findings suggest that miR-499a-5p might represent a novel target that regulates brain injury by inhibiting PDCD4-mediating apoptosis.

Downregulation of miR-499a-5p Predicts a Poor Prognosis of Patients With Non-Small Cell Lung Cancer and Restrains the Tumorigenesis by Targeting Fibroblast Growth Factor 9

The aberrant expression of microRNA is an important regulator in the tumorigenesis of non-small cell lung cancer. In this study, we found that miR-499a-5p was notably downregulated in non-small cell lung cancer tissues and cell lines. Decreased miR-499a-5p expression was associated with larger tumor size and higher TNM stage. Non-small cell lung cancer patients with low expression of miR-499a-5p exhibited a worse overall survival rate compared with those patients with high expression of miR-499a-5p. Ectopic expression of miR-499a-5p significantly suppressed non-small cell lung cancer cell proliferation and colony formation, and hampered cell cycle at G0/G1 phase in vitro. Conversely, knockdown of miR-499a-5p promoted non-small cell lung cancer cell proliferation and colony formation, and induced cell cycle at S phase. Furthermore, in vivo experiments revealed that overexpression of miR-499a-5p inhibited the tumor formation in a nude mouse xenograft model. Mechanistic studies showed that fibroblast growth factor 9 was a direct target gene of miR-499a-5p. miR-499a-5p directly bound to fibroblast growth factor 9 mRNA 3’-UTR, therefore led to the reduction in fibroblast growth factor 9 protein expression. Finally, rescue experiments confirmed that silencing of fibroblast growth factor 9 partially reversed the phenotypes of miR-499a-5p knockdown on non-small cell lung cancer cell proliferation. In conclusion, our study demonstrates that downregulation of miR-499a-5p predicts a worse prognosis of patients with non-small cell lung cancer and restrains the tumorigenesis by targeting fibroblast growth factor 9. These findings may provide valuable clues for the future development of therapeutic strategies against this cancer.

The role of PPM1D in cancer and advances in studies of its inhibitors

A greater understanding of factors causing cancer initiation, progression and evolution is of paramount importance. Among them, the serine/threonine phosphatase PPM1D, also referred to as wild-type p53-induced phosphatase 1 (Wip1) or protein phosphatase 2C delta (PP2Cδ), is emerging as an important oncoprotein due to its negative regulation on a number of crucial cancer suppressor pathways. Initially identified as a p53-regulated gene, PPM1D has been afterwards found amplified and more recently mutated in many human cancers such as breast cancer. The latest progress in this field further reveals that selective inhibition of PPM1D to delay tumor onset or reduce tumor burden represents a promising anti-cancer strategy. Here, we review the advances in the studies of the PPM1D activity and its relevance to various cancers, and recent progress in development of PPM1D inhibitors and discuss their potential application in cancer therapy. Consecutive research on PPM1D and its relationship with cancer is essential, as it ultimately contributes to the etiology and treatment of cancer.

MiR-499a-5p Inhibits Proliferation, Invasion, Migration, and Epithelial-Mesenchymal Transition, and Enhances Radiosensitivity of Cervical Cancer Cells via Targeting eIF4E

Introduction

The present study aimed to explore the role of miR-499a-5p and its molecular mechanism in cervical cancer (CC).

Methods

Quantitative real-time PCR (QRT-PCR) and Western blotting were performed to detect the expression of miR-499a-5p and eukaryotic translation initiation factor 4E (eIF4E) in CC tissues and cell lines. The proliferation, migration, and invasion of CC cells were detected by MTT assay, wound healing assay, and Transwell assay. Apoptosis was evaluated by flow cytometry and alterations of apoptosis-related genes. The effect of miR-499a-5p on epithelial-mesenchymal transition (EMT) was examined by determining the protein levels of EMT-associated genes. Then, colony formation assay was used to determine the radiosensitivity of CC cells. A dual-luciferase reporter assay was performed to confirm the direct target of miR-499a-5p.

Results

MiR-499a-5p was significantly downregulated in CC tissues and cell lines. Overexpression of miR-499a-5p or eIF4E knockdown markedly inhibited cell proliferation, invasion, migration, and EMT, and enhanced apoptosis. eIF4E was predicted and verified as a target gene of miR-499a-5p. The influence of miR-499a-5p upregulation on proliferation, apoptosis, invasion, migration, EMT, and radiosensitivity was abrogated by eIF4E overexpression.

Discussion

MiR-499a-5p promoted the apoptosis and radiosensitivity and inhibited proliferation, invasion, migration, and EMT by directly targeting eIF4E in CC cells.

Knockdown of LncRNA SCAMP1 suppressed malignant biological behaviours of glioma cells via modulating miR-499a-5p/LMX1A/NLRC5 pathway

Dysregulation of long non‐coding RNAs (lncRNAs) confirm that it plays a crucial role in tumourigenesis and malignant progression of glioma. The present study demonstrated that LncRNA secretory carrier membrane protein 1 (SCAMP1) was up‐regulated and functioned as an oncogene in glioma cells. In addition, miR‐499a‐5p was down‐regulated meanwhile exerted tumour‐suppressive function in glioma cells. Subsequently, inhibition of SCAMP1 significantly restrained the cell proliferation, migration and invasion, as well as promoted apoptosis by acting as a molecular sponge of miR‐499a‐5p. Transcription factor LIM homeobox transcription factor 1, alpha (LMX1A) was overexpressed in glioma tissues and cells. Moreover, miR‐499a‐5p targeted LMX1A 3′‐UTR in a sequence‐specific manner. Hence, down‐regulation of SCAMP1 remarkably reduced the expression level of LMX1A, indicating that LMX1A participated in miR‐499a‐5p‐induced tumour‐suppressive effects on glioma cells. Furthermore, knockdown of LMX1A decreased NLR family, CARD domain containing 5 (NLRC5) mRNA and protein expression levels through directly binding to the NLRC5 promoter region. Down‐regulation of NLRC5 obviously inhibited malignant biological behaviours of glioma cells through attenuating the activity of Wnt/β‐catenin signalling pathway. In conclusion, our study clarifies that SCAMP1/miR‐499a‐5p/LMX1A/NLRC5 axis plays a critical role in modulating malignant progression of glioma cells, which provide a novel therapeutic strategy for glioma treatment.

The TGFβ-miR-499a-SHKBP1 pathway induces resistance to EGFR inhibitors in osteosarcoma cancer stem cell-like cells

Background/aims

A novel paradigm in tumor biology suggests that osteosarcoma (OS) chemo-resistance is driven by osteosarcoma stem cell-like cells (OSCs). As the sensitivity of only a few tumors to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) can be explained by the presence of EGFR tyrosine kinase (TK) domain mutations, there is a need to elucidate mechanisms of resistance to EGFR-targeted therapies in OS that do not harbor TK sensitizing mutations to develop new strategies to circumvent resistance to EGFR inhibitors.

Methods

As a measure of the characters of OSCs, serum-free cultivation, cell viability test with erlotinib, and serial transplantation in vivo was used. Western blot assays were used to detect the association between erlotinib resistance and transforming growth factor beta (TGFβ)-induced epithelial-to-mesenchymal transition (EMT) progression. By using TaqMan qPCR miRNA array, online prediction software, luciferase reporter assays and western blot analysis, we further elucidated the mechanisms.

Results

Here, CD166⁺ cells are found in 10 out of 10 tumor samples. We characterize that CD166⁺ cells from primary OS tissues bear hallmarks of OSCs and erlotinib-resistance. TGFβ-induced EMT-associated kinase switch is demonstrated to promote erlotinib-resistance of CD166⁺ OSCs. Further mechanisms study show that TGFβ-induced EMT decreases miR-499a expression through the direct binding of Snail1/Zeb1 to miR-499a promoter. Overexpression of miR-499a in CD166⁺ OSCs inhibits TGFβ-induced erlotinib-resistance in vitro and in vivo. SHKBP1, the direct target of miR-499a, regulates EGFR activity reduction occurring concomitantly with a TGFβ-induced EMT-associated kinase switch to an AKT-activated EGFR-independent state. TGFβ-induced activation of AKT co-opts an increased SHKBP1 expression, which further regulates EGFR activity. In clinic, the ratio of the expression levels of SHKBP1 and miR-499a is highly correlated with EMT and resistance to erlotinib.

Conclusion

TGFβ–miR-499a–SHKBP1 network orchestrates the EMT-associated kinase switch that induces resistance to EGFR inhibitors in CD166⁺ OSCs, implies that inhibition of TGFβ induced EMT-associated kinase switch may reverse the chemo-resistance of OSCs to EGFR inhibitors. We also suggest that an elevated SHKBP1/miR-499a ratio is a molecular signature that characterizes the erlotinib-resistant OS, which may have clinical value as a predictive biomarker.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1195-y) contains supplementary material, which is available to authorized users.