miR-1224-5p inhibits the proliferation and invasion of ovarian cancer via targeting SND1

circPOLA2 promotes proliferation, invasion, migration, and epithelial-mesenchymal transition in breast cancer via the miR-1224-5p/HMGA2 axis

OBJECTIVE

This study aimed to investigate the carcinogenic role of circPOLA2 in Breast Cancer (BC) and reveal its potential mechanism as a competitive endogenous RNA.

METHODS

Differentially expressed circRNAs, miRNAs, and mRNAs in BC tissues and cell lines were screened and analyzed by RT-qPCR. The interaction among circPOLA2, miR-1224-5p, and HMGA2 was tested using dual luciferase reporter assay and RNA pull-down assay. Cell proliferation was detected by MTT and colony formation assay, apoptosis was detected by flow cytometry, migration, and invasion was detected by Transwell assay, and EMT-related proteins were detected by Western blot.

RESULTS

circPOLA2 and HMGA2 levels were elevated in BC, while miR-1224-5p level was reduced. Knocking down circPOLA2 decreased the expression of HMGA2 by elevating miR-1224-5p expression. Knocking down circPOLA2 or HMGA2 or elevating miR-1224-5p reduced the proliferative, migratory, invasive, and anti-apoptotic capacities of BC cells.

CONCLUSION

Knockdown of circPOLA2 inhibits BC cell proliferation, migration, and invasion and delays BC tumor progression by regulating the miR-1224-5p/HMGA2 axis, providing a new strategy and target for therapeutic intervention in BC.

Plasma-derived exosomal miRNA profiles reveal potential epigenetic pathogenesis of premature ovarian failure

The role of plasma-derived exosomal miRNA in premature ovarian failure (POF) remains unclear. This study aimed to investigate the epigenetic pathogenesis of POF through exosomal miRNA sequencing. Exosomes were isolated and characterized from six POF patients and four healthy individuals using nanoparticle tracking analysis, transmission electron microscopy and western blot analysis. Exosomal miRNA sequencing was performed to identify differentially expressed miRNAs with |fold change| greater than 1.5 and p value less than 0.05. Bioinformatics analysis in GSE39501 dataset and our sequencing data was conducted to investigate underlying mechanisms of POF. The functional role of hsa-miR-19b-3p was assessed using CCK8, western blot, flow cytometry and fluorescence staining. The regulatory effect of hsa-miR-19b-3p on BMPR2 was investigated through miRNA transfection, qPCR analysis, and luciferase reporter assay. Statistical significance was determined using t-tests and one-way ANOVA (p < 0.05). Exosomal miRNA sequencing revealed 18 dysregulated miRNAs in POF patients compared to healthy controls. Functional enrichment analysis demonstrated their involvement in cell growth, oocyte meiosis and PI3K-Akt signaling pathways. Moreover, the constructed miRNA-mRNA network unveiled potential regulatory mechanisms underlying POF, particularly implicating hsa-miR-19b-3p in the regulation of BMPR2. In vitro assays conducted on KGN cells confirmed that hsa-miR-19b-3p promoted apoptosis, as evidenced by reduced cell viability, decayed mitochondrial membrane potential and increased apoptotic rate, thereby supporting its role in POF. Notably, hsa-miR-19b-3p was found to significantly downregulate BMPR2 expression via targeting its 3'UTR, while co-expression analysis revealed strong associations between BMPR2 and POF-related processes. This study sheds light on the epigenetic pathogenesis of POF by investigating exosomal miRNA profiles. Particularly, hsa-miR-19b-3p emerged as a potential regulator of BMPR2 and demonstrated its functional significance in POF through modulation of apoptosis.

Circ_0000115 Protects Against Cerebral Ischemia Injury by Suppressing Neuronal Apoptosis, Oxidative Stress and Inflammation by miR-1224-5p/Nos3 Axis In Vitro

Cerebral ischemia is a severe neurological disability related to neuronal apoptosis and cellular stress response. Circular RNAs (circRNAs) are emerging regulators of cerebral ischemia. Herein, this study proposed to probe the action of circ_0000115 in cerebral ischemia injury. The mouse neuroblastoma cells N2a and HT22 underwent oxygen-glucose deprivation (OGD) were used as a model of in vitro cerebral ischemia. Levels of genes and proteins were detected by qRT-PCR and western blotting. Cell proliferation and apoptosis were determined by EdU assay and flow cytometry. Western blotting was used to detect the protein level of pro-inflammatory factors. The oxidative stress injury was evaluated by detecting reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) generation. Dual-luciferase reporter and RIP assays were used to confirm the target relationship between miR-1224-5p and circ_0000115 or nitric oxide synthase 3 (NOS3). OGD exposure decreased circ_0000115 and NOS3 expression, and increased miR-1224-5p in N2a and HT22 cells in a time-dependent manner. Circ_0000115 silencing attenuated OGD-induced apoptosis, oxidative stress and inflammation in N2a and HT22 cells. Mechanistically, circ_0000115 directly sponged miR-1224-5p, which targeted NOS3. Furthermore, rescue experiments showed that miR-1224-5p overexpression abolished the neuroprotective effect of circ_0000115 in N2a and HT22 cells under OGD treatment. Besides that, silencing of miR-1224-5p protected N2a and HT22 cells against OGD-evoked injury, which was counteracted by NOS3 knockdown. Circ_0000115 protects N2a and HT22 cells against OGD-evoked neuronal apoptosis, inflammation, and oxidative stress via the miR-1224-5p/NOS3 axis, providing an exciting view of the pathogenesis of cerebral ischemia.

IGFL2-AS1 facilitates tongue squamous cell carcinoma progression via Wnt/β-catenin signaling pathway

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is the most common malignancy in oral cancer. Long noncoding RNAs (lncRNAs) are important regulators in cancer biology. In our present study, we investigated a novel lncRNA IGF-like family member 2 antisense RNA 1 (IGFL2-AS1) in TSCC.

METHODS

RT-qPCR analyzed IGFL2-AS1 expression in TSCC cells. Functional assays assessed the impact of IGFL2-AS1 on TSCC cell proliferation, migration, and invasion. Western blot analyzed the protein levels of EMT-related markers. Mechanism assays analyzed the regulatory mechanism of IGFL2-AS1 in TSCC cells. In-vivo experiments were conducted to prove the role of IGFL2-AS1 in TSCC progression.

RESULTS

IGFL2-AS1 was significantly up-regulated in TSCC cells and tissues, and IGFL2-AS1 knockdown inhibited cell proliferation, migration, invasion and EMT in TSCC. Moreover, IGFL2-AS1 functioned as a competing endogenous RNA (ceRNA) to sponge miR-1224-5p and thereby modulated SATB homeobox 1 (SATB1) expression. Additionally, SATB1 activated the Wnt/β-catenin signaling pathway in TSCC cells and IGFL2-AS1 regulated the Wnt/β-catenin signaling pathway and TSCC progression via elevating SATB1 expression.

CONCLUSIONS

The data revealed that IGFL2-AS1 played a cancer promoting role in TSCC and may aid in exploring a brand new biomarker that might contribute to TSCC treatment.

Proteomic Discovery of Plasma Protein Biomarkers and Development of Models Predicting Prognosis of High-Grade Serous Ovarian Carcinoma

Ovarian cancer is one of the most lethal female cancers. For accurate prognosis prediction, this study aimed to investigate novel, blood-based prognostic biomarkers for high-grade serous ovarian carcinoma (HGSOC) using mass spectrometry-based proteomics methods. We conducted label-free liquid chromatography-tandem mass spectrometry using frozen plasma samples obtained from patients with newly diagnosed HGSOC (n = 20). Based on progression-free survival (PFS), the samples were divided into two groups: good (PFS ≥18 months) and poor prognosis groups (PFS <18 months). Proteomic profiles were compared between the two groups. Referring to proteomics data that we previously obtained using frozen cancer tissues from chemotherapy-naïve patients with HGSOC, overlapping protein biomarkers were selected as candidate biomarkers. Biomarkers were validated using an independent set of HGSOC plasma samples (n = 202) via enzyme-linked immunosorbent assay (ELISA). To construct models predicting the 18-month PFS rate, we performed stepwise selection based on the area under the receiver operating characteristic curve (AUC) with 5-fold cross-validation. Analysis of differentially expressed proteins in plasma samples revealed that 35 and 61 proteins were upregulated in the good and poor prognosis groups, respectively. Through hierarchical clustering and bioinformatic analyses, GSN, VCAN, SND1, SIGLEC14, CD163, and PRMT1 were selected as candidate biomarkers and were subjected to ELISA. In multivariate analysis, plasma GSN was identified as an independent poor prognostic biomarker for PFS (adjusted hazard ratio, 1.556; 95% confidence interval, 1.073-2.256; p = 0.020). By combining clinical factors and ELISA results, we constructed several models to predict the 18-month PFS rate. A model consisting of four predictors (FIGO stage, residual tumor after surgery, and plasma levels of GSN and VCAN) showed the best predictive performance (mean validated AUC, 0.779). The newly developed model was converted to a nomogram for clinical use. Our study results provided insights into protein biomarkers, which might offer clues for developing therapeutic targets.

Inhibition of miR-141-3p attenuates apoptosis of neural stem cells via targeting PBX1 to regulate PROK2 transcription in MCAO mice

MicroRNA-141-3p (miR-141-3p) has been found to be altered in the brain following a stroke. Herein, we investigate the impact of miR-141-3p on the apoptosis of neural stem cells (NSCs) in mice with middle cerebral artery occlusion (MCAO) and the potential mechanisms involved. Eight-week-old mice were injected intracerebroventricularly with miR-141-3p, antagomir-141-3p, or agomir negative control 2 h before MCAO, and animal behavior tests and infraction volume measurements were performed 24 h later. MCAO-mediated brain injury and NSCs apoptosis were observed by H&E, TTC, and TUNEL staining. The expression of cleaved caspase-3 and Ki67 was detected by western blotting. The luciferase reporter assay proved that miR-141-3p in combination with its target gene PBX homeobox 1 (PBX1). Exogenous miR-141-3p (agomir-141-3p) treatment increased infraction volume and brain edema and damaged neurological functions compared to control mice. Agomir-141-3p increased miR-141-3p expression in brain tissue of mice with MCAO and suppressed PBX1 expression. The effects of the agomir-141-3p-induced apoptosis in NSCs treated with oxygen-glucose deprivation (OGD)/reoxygenation (R) were abolished by PBX1 overexpression. The results from UCSC and JASPAR database showed that prokineticin 2 (PROK2) was a transcription factor of PBX1. The expression of PROK2 was transcriptionally regulated by PBX1 using RT-PCR and western blot assays. The effects of the apoptosis-promoting caused by PBX1 inhibition in NSCs treated with OGD/R were reversed by PROK2 inhibition. In conclusion, the miR-141-3p/PBX1/PROK2 axis might be a novel therapeutic target for the apoptosis of NSCs in MCAO.

Effect of Bone Marrow Mesenchymal Stem Cells (BMSCs) with High miR-183-5p Expression on Ovarian Cancer Cells by Regulating Signal Transducer and Activator of Transcription 3 (STAT3)

Currently, the treatment for ovarian cancer (OC) is not satisfactory. The microRNAs may have an important function in tumor pathogenesis. miR-183-5p involves in several tumors. However, its effect on OC cells is unclear. The BMSCs could regulate the micro-environment of tumor and participate in tumor procession. In this study, effect of BMSCs with highly-expressed miR-183-5p on OC cells was assessed. The BMSCs with highly-expressed miR-183-5p was established and co-cultivated with OC cell line SKOV3 followed by measuring miR-183-5p level by PCR, STAT3 and ADAM9 expression by western blot. miR-183-5p level in OC cells was reduced and further decreased after co-culture with BMSCs along with enhance cell proliferation and upregulated STAT3 expression (P < 0.05). In addition, miR-183-5p level was increased in BMSCs with highly-expressed miR-183-5p and STAT3 expression was reduced along with restrained cell proliferation (P < 0.05). In conclusion, miR-183-5p in OC cells is downregulated and malignant biological behaviors of OC cells are restrained by BMSCs with highly-expressed miR-183-5p possibly through regulating the expression of STAT3.

Inflammation and Oxidative Stress Role of S100A12 as a Potential Diagnostic and Therapeutic Biomarker in Acute Myocardial Infarction

Acute myocardial infarction (AMI) is one of the most serious cardiovascular diseases with high morbidity and mortality. Numerous studies have indicated that S100A12 may has an essential role in the occurrence and development of AMI, and in-depth studies are currently lacking. The purpose of this study is to investigate the effect of S100A12 on inflammation and oxidative stress and to determine its clinical applicability in AMI. Here, AMI datasets used to explore the expression pattern of S100A12 in AMI were derived from the Gene Expression Omnibus (GEO) database. The pooled standard average deviation (SMD) was calculated to further determine S100A12 expression. The overlapping differentially expressed genes (DEGs) contained in all included datasets were recognized by the GEO2R tool. Then, functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, were carried out to determine the molecular function of overlapping DEGs. Gene set enrichment analysis (GSEA) was conducted to determine unrevealed mechanisms of S100A12. Summary receiver operating characteristic (SROC) curve analysis and receiver operating characteristic (ROC) curve analysis were carried out to identify the diagnostic capabilities of S100A12. Moreover, we screened miRNAs targeting S100A12 using three online databases (miRWalk, TargetScan, and miRDB). In addition, by comprehensively using enzyme-linked immunosorbent assay (ELISA), real-time quantitative PCR (RT-qPCR), Western blotting (WB) methods, etc., we used the AC16 cells to validate the expression and underlying mechanism of S100A12. In our study, five datasets related to AMI, GSE24519, GSE60993, GSE66360, GSE97320, and GSE48060 were included; 412 overlapping DEGs were identified. Protein-protein interaction (PPI) network and functional analyses showed that S100A12 was a pivotal gene related to inflammation and oxidative stress. Then, S100A12 overexpression was identified based on the included datasets. The pooled standard average deviation (SMD) also showed that S100A12 was upregulated in AMI (SMD = 1.36, 95% CI: 0.70-2.03, p = 0.024). The SROC curve analysis result suggested that S100A12 had remarkable diagnostic ability in AMI (AUC = 0.90, 95% CI: 0.87-0.92). And nine miRNAs targeting S100A12 were also identified. Additionally, the overexpression of S100A12 was further confirmed that it maybe promote inflammation and oxidative stress in AMI through comprehensive in vitro experiments. In summary, our study suggests that overexpressed S100A12 may be a latent diagnostic biomarker and therapeutic target of AMI that induces excessive inflammation and oxidative stress. Nine miRNAs targeting S100A12 may play a crucial role in AMI, but further studies are still needed. Our work provides a positive inspiration for the in-depth study of S100A12 in AMI.

The Role and Mechanism of microRNA-1224 in Human Cancer

microRNAs (miRNAs) are a type of small endogenous non-coding RNAs composed of 20-22 nucleotides, which can regulate the expression of a gene by targeting 3’ untranslated region (3’-UTR) of mRNA. Many studies have reported that miRNAs are involved in the occurrence and progression of human diseases, including malignant tumors. miR-1224 plays significant roles in different tumors, including tumor proliferation, metastasis, invasion, angiogenesis, biological metabolism, and drug resistance. Mostly, it serves as a tumor suppressor. With accumulating proofs of miR-1224, it can act as a potential bio-indicator in the diagnosis and prognosis of patients with cancer. In this article, we review the characteristics and research progress of miR-1224 and emphasize the regulation and function of miR-1224 in different cancer. Furthermore, we conclude the clinical implications of miR-1224. This review may provide new horizons for deeply understanding the role of miR-1224 as biomarkers and therapeutic targets in human cancer.

Noncoding RNAs Interplay in Ovarian Cancer Therapy and Drug Resistance

Noncoding RNAs (ncRNAs) are several types of RNA that do not encode proteins, but are essential for cell regulation. Ovarian cancer (OC) is a type of gynecological cancer with a high mortality rate and a 5-year prognosis. OC is becoming more common with each passing year, and the symptoms of early-stage OC are sometimes undetectable. Meanwhile, early-stage OC has no symptoms and is difficult to diagnose. Because ncRNA has been shown to affect the development of OC and is widely distributed, it could be employed as a new biomarker for early OC. Furthermore, ncRNA has the potential to promote or inhibit drug resistance in OC, potentially giving a solution to multiple drug resistance. Various prior studies have found that different ncRNAs perform differently in OC. This article examines how mainstream ncRNAs have been expressed in OC in recent years, as well as their function in tumor growth.

microRNA-671-5p reduces tumorigenicity of ovarian cancer via suppressing HDAC5 and HIF-1α expression

OBJECTIVE

microRNA (miR)-based therapeutic reference has been established and expanded in the treatment of cancers. For this reason, we explored how miR-671-5p regulated tumorigenicity of ovarian cancer (OC) through regulating histone deacetylase 5 (HDAC5) and hypoxia-inducible factor-1α (HIF-1α).

METHODS

miR-671-5p, HDAC5 and HIF-1α expression levels were determined in OC clinical tissues. The OC cell line H8910 was screened and transfected with the vector that altered miR-671-5p, HDAC5 and HIF-1α levels. Finally, the proliferation, migration, invasion and apoptosis of the transfected H8910 cells were determined and the role of miR-671-5p and HDAC5 in vivo tumor growth was further discussed.

RESULTS

Low miR-671-5p and high HDAC5 and HIF-1α levels were tested in OC tissues. Up-regulating miR-671-5p or down-regulating HDAC5 or HIF-1α suppressed proliferation, migration, invasion and augmented apoptosis of H8910 cells while the silenced miR-671-5p or enhanced HDAC5 caused the opposite consequences. Overexpression of HDAC5 reduced while depletion of HDAC5 enhanced the influence of up-regulated miR-671-5p on OC cell growth. In animal models, suppressing miR-671-5p or promoting HDAC5 encouraged OC tumor growth.

CONCLUSION

A summary delineates that miR-671-5p reduces tumorigenicity of OC via suppressing HDAC5 and HIF-1α levels.

Circ-RNF121 regulates tumor progression and glucose metabolism by miR-1224-5p/FOXM1 axis in colorectal cancer

Aim

Previous studies have reported that circular RNA (circRNA) is associated with the pathogenesis of CRC. This study was designed to reveal the mechanism of circ-ring finger protein 121 (circ-RNF121) in colorectal cancer (CRC).

Materials and methods

The levels of circ-RNF121, microRNA-1224-5p (miR-1224-5p) and forkhead box M1 (FOXM1) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Protein level was detected by western blot. Cell proliferation was analyzed by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and cell colony formation assays. Flow cytometry analysis was performed to investigate cell apoptosis. Cell migration and invasion were investigated by transwell and wound-healing assays. Cell glycolysis was detected using glucose, lactate and ADP/ATP ratio assay kits. The binding relationship between miR-1224-5p and circ-RNF121 or FOXM1 was predicted by starBase online database, and identified by dual-luciferase reporter assay. The impacts of circ-RNF121 silencing on tumor formation in vivo were disclosed by in vivo tumor formation assay.

Key findings

Circ-RNF121 and FOXM1 expression were dramatically upregulated, while miR-1224-5p expression was downregulated in CRC tissues or cells compared with control groups. Circ-RNF121 silencing repressed cell proliferation, migration, invasion and glycolysis but induced cell apoptosis in CRC, which were attenuated by miR-1224-5p inhibitor. Additionally, circ-RNF121 acted as a sponge of miR-1224-5p and miR-1224-5p bound to FOXM1. Circ-RNF121 silencing inhibited tumor growth in vivo. Furthermore, circ-RNF121 was secreted through being packaged into exosomes.

Significance

The finding provided a novel insight into studying circRNA-mediated CRC therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02290-3.

MiR-192-5p inhibits proliferation, migration, and invasion in papillary thyroid carcinoma cells by regulation of SH3RF3

Background: The decreased level of miR-192-5p has been reported in several kinds of cancers, including bladder, colon, ovarian, and non-small cell lung cancer. However, the expression and function of miR-192-5p in papillary thyroid carcinoma/cancer (PTC) remains unknown.

Objective: The present study aimed to explore the function and underlying mechanism of miR-192-5p in PTC development.

Methods: PTC tissues and relative normal controls from PTC patients were collected. qRT-PCR analysis was performed to measure miR-192-5p and SH3RF3 mRNA level in PTC tissues and cell lines. CCK-8 method and FCM assay were used to test cell proliferation and apoptosis in TPC-1 cells, respectively. The abilities of cell migration and invasion were detected by wound healing and transwell assays, respectively. The protein expression was evaluated by Western blot. The interaction between miR-192-5p and Src homology 3 (SH3) domain containing ring finger 3 (SH3RF3) were confirmed by dual-luciferase reporter assay.

Results: MiR-192-5p level was obviously decreased in PTC tissues and cell lines. Overexpression of miR-192-5p suppressed proliferation, migration, invasion, and EMT process, while induced apoptosis in TPC-1 cells. In addition, miR-192-5p negatively modulated SH3RF3 expression by binding to its 3′-untranslated region (3′UTR). Silencing SH3RF3 inhibited the migration, invasion, and EMT of TPC-1 cells. In the meantime, matrine, an alkaloid extracted from herb, exerted its anti-cancer effects in PTC cells dependent on increase in miR-192-5p expression and decrease in SH3RF3 expression.

Conclusion: We firstly declared that miR-192-5p played a tumor suppressive role in PTC via targeting SH3RF3. Moreover, matrine exerted its anti-cancer effects in PTC via regulating miR-192-5p/SH3RF3 pathway.

Exosomal-mediated transfer of APCDD1L-AS1 induces 5-fluorouracil resistance in oral squamous cell carcinoma via miR-1224-5p/nuclear receptor binding SET domain protein 2 (NSD2) axis

Oral squamous cell carcinoma (OSCC) poses a threat to public health worldwide. LncRNA APCDD1L-AS1 has been reported to participate in tumorigenesis and development of acquired chemoresistance. However, the role of APCDD1L-AS1 in 5-fluorouracil (5-FU) resistance regulation within OSCC is still obscure. In this study, 5-FU-resistant cell models were established with OSCC cell lines (HSC-3 and HN-4). Gene expressions and protein levels were detected by RT-qPCR and Western blotting, respectively. CCK-8, colony forming, and flow cytometry were utilized to measure IC50 value, cell viability, and cell apoptosis of 5-FU-resistant OSCC cells. Dual-luciferase reporter assay and RIP assay were applied to identify the associations between miR-1224-5p and APCDD1L-AS1 or NSD2. Herein, high APCDD1L-AS1 expression was shown in OSCC tissues and cells resistant to 5-FU and related to the worse prognosis of OSCC patients. APCDD1L-AS1 knockdown impaired 5-FU resistance in 5-FU-resistant OSCC cells by reducing IC₅₀ value, suppressing cell viability, and accelerating cell apoptosis. Besides, extracellular APCDD1L-AS1 could be transferred to sensitive cells via exosome incorporation, thereby transmitting 5-FU resistance in OSCC cells. Besides, miR-1224-5p was a molecular target of APCDD1L-AS1 and directly targeted NSD2 in 5-FU-resistant cells. MiR-1224-5p exhibited a much lower level in 5-FU-resistant tissues and increased 5-FU sensitivity in 5-FU-resistant OSCC cells. Moreover, NSD2 upregulation neutralized the influence of blocking APCDD1L-AS1 in HSC-3/5-FU and HN-4/5-FU cells on 5-FU resistance. To sum up, our study demonstrated that exosomal APCDD1L-AS1 conferred resistance to 5-FU in HSC-3/5-FU and HN-4/5-FU cells via the miR-1224-5p/NSD2 axis, thus providing a novel target for OSCC chemoresistance.

Splice and Dice: Intronic microRNAs, Splicing and Cancer

Introns span only a quarter of the human genome, yet they host around 60% of all known microRNAs. Emerging evidence indicates the adaptive advantage of microRNAs residing within introns is attributed to their complex co-regulation with transcription and alternative splicing of their host genes. Intronic microRNAs are often co-expressed with their host genes, thereby providing functional synergism or antagonism that is exploited or decoupled in cancer. Additionally, intronic microRNA biogenesis and the alternative splicing of host transcript are co-regulated and intertwined. The importance of intronic microRNAs is under-recognized in relation to the pathogenesis of cancer.

MiR-1224-5p Activates Autophagy, Cell Invasion and Inhibits Epithelial-to-Mesenchymal Transition in Osteosarcoma Cells by Directly Targeting PLK1 Through PI3K/AKT/mTOR Signaling Pathway

Background

Osteosarcoma (OS) is one of the most common malignant bone tumors with a poor overall prognosis. MiR-1224-5p plays an important role in cancer, but its function and mechanism in OS have not been studied.

Materials and Methods

The expression of miR-1224-5p and PLK1 was detected by qRT-PCR in OS cells, adjacent tissues, and cell lines. Dual-luciferase reporter gene assay was used to verify the interaction between miR-1224-5p and PLK1. The expression of miR-1224-5p and PLK1 was intervened by transfection with miR-1224-5p mimic, NC mimic, pc-NC and PLK1, respectively. MTT, colony formation assay, Transwell and flow cytometry were used to observe the cell proliferation, invasion and apoptosis. Western blot was used to detect the expression levels of PLK1, PI3K/AKT/mTOR signaling pathway-related proteins, autophagy-related proteins, and epithelial-mesenchymal transition (EMT)-related proteins in the cells.

Results

We found that miR-1224-5p was down-regulated and PLK1 expression was up-regulated in OS tissues and cells. On the other hand, it is further confirmed that PLK1 was a target gene of miR-1224-5p. Overexpression of miR-1224-5p inhibited the proliferation, invasion while promoted the apoptosis of OS cells, whereas overexpression of PLK1 promoted the proliferation, invasion and inhibited the apoptosis of OS cells. In the miR-1224-5p group (overexpression of miR-1224-5p), PI3K, AKT, and mTOR protein phosphorylation levels were significantly reduced, while autophagic activity was significantly activated, and the degree of EMT was significantly reduced. But the results in the PLK1 group (overexpression of PLK1) were the opposite. In addition, overexpression of miR-1224-5p reversed the effect of PLK1 upregulation on OS cells.

Conclusion

MiR-1224-5p targets PLK1 to inhibit PI3K/AKT/mTOR signaling pathway, thus mediating the proliferation, invasion, apoptosis, autophagy and EMT in OS cells.