Activation/Proliferation-associated Protein 2 (Caprin-2) Positively Regulates CDK14/Cyclin Y-mediated Lipoprotein Receptor-related Protein 5 and 6 (LRP5/6) Constitutive Phosphorylation

CDK14 regulates the development and repair of lung

Cyclin-dependent kinases (CDK) 14 regulates cell cycle, tumor expansion by influencing the downstream targets of the canonical Wnt signaling pathway. However, the function of CDK14 during organ development and regeneration has not been investigated in genetically-modified animals. Here, we found that genetic ablation of Cdk14 influenced pulmonary vascular endothelial cells and alveolar epithelial cells during mice embryonic development as well as repair of lung after bleomycin or lipopolysaccharide induced injury. Genetic knockout of Cdk14 and the CDK14 covalent inhibitor FMF-04-159-2 resulted in reduction of pulmonary vessel covered area and epithelial cell number, exhibiting increased mortality and more severe lung damage after injury. Mechanistically, Cdk14 ablation inhibited the proliferation of epithelial and vascular endothelial cells, inducing cell cycle arrest at the G2/M phase. Through RNA-seq analysis of both endothelial and epithelial cells, we found that knockdown of Cdk14 controls the expression of signal transducers and activator of transcription 1 (STAT1) as well as associated genes in interferon signaling. Disruption of Cdk14 interferes with IFN-γ induced lung repair in vivo, suggesting potential crosstalk of CDK14 signaling and IFN-γ pathway. Our work highlights the importance of Cdk14 in lung development and regenerative repair through an uncharacterized CDK14- IFN-γ signaling axis.

CDK14 is regulated by IGF2BP2 and involved in osteogenic differentiation via Wnt/β-catenin signaling pathway in vitro

AIMS

Cyclin-dependent kinase (CDK) family proteins involve in various cellular processes via regulating the cell cycle; however, their expression during osteogenic differentiation and postmenopausal osteoporosis remains poorly understood.

MAIN METHODS

Using bioinformatics, we screened for CDK14 bound to Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) and explored its expression in vitro with time-gradient model and in a mouse model of postmenopausal osteoporosis, building on prior research. Subsequently, we investigated its effect on osteoblast proliferation, cell cycle dynamics, and osteogenic differentiation by administering CDK14 siRNA and the covalent inhibitor FMF-04-159-2. Furthermore, we examined the interaction between IGF2BP2 and CDK14. Finally, we validated the regulatory role of CDK14 on the Wnt/β-catenin pathway.

KEY FINDINGS

Our findings demonstrate a time-dependent CDK14 expression patterns during osteogenic differentiation of MC3T3-E1 cell line, with an initial increase followed by gradual decline over time. Notably, CDK14 expression exhibited significant reduction in bone tissue of postmenopausal osteoporosis mouse model. CDK14 inhibition altered osteoblast cell cycle dynamics, significantly reduced cellular proliferation capacity, and impaired osteogenic differentiation ability. IGF2BP2 interacted with CDK14 mRNA, and stabilizing mRNA's structure and inhibiting its degradation. Additionally, CDK14 facilitated Low-density lipoprotein receptor-related protein 6 (LRP6) and Glycogen synthase kinase 3β (GSK3β) phosphorylation, thus regulating β-catenin levels.

SIGNIFICANCE

These findings provide further insight into the molecular mechanisms governing osteoblast proliferation, differentiation and osteoporosis.

A Huluwa phosphorylation switch regulates embryonic axis induction

Embryonic axis formation is essential for patterning and morphogenesis in vertebrates and is tightly regulated by the dorsal organizer. Previously, we demonstrated that maternally derived Huluwa (Hwa) acts as a dorsal determinant, dictating axis formation by activating β-catenin signaling in zebrafish and Xenopus. However, the mechanism of activation and fine regulation of the Hwa protein remains unclear. Through candidate screening we identified a mutation at Ser168 in the PPNSP motif of Hwa that dramatically abolishes its axis-inducing activity. Mechanistically, mutating the Ser168 residue reduced its binding affinity to Tankyrase 1/2 and the degradation of the Axin protein, weakening β-catenin signaling activation. We confirmed that Ser168 is phosphorylated and that phosphorylation increases Hwa activity in β-catenin signaling and axis induction. Several kinases including Cdk16, Cdk2, and GSK3β, were found to enhance Ser168 phosphorylation in vitro and in vivo. Both dominant-negative Cdk16 expression and pHwa (Ser168) antibody treatment reduce Hwa function. Lastly, a knock-in allele mutating Ser168 to alanine resulted in embryos lacking body axes, demonstrating that Ser168 is essential to axis formation. In summary, Ser168 acts as a phosphorylation switch in Hwa/β-catenin signaling for embryonic axis induction, regulated by multiple kinases.

Structural insights into the Caprin-2 HR1 domain in canonical Wnt signaling

The canonical Wnt signaling pathway plays crucial roles in cell fate decisions as well as in pathogenesis of various diseases. Previously, we reported Caprin-2 as a new regulator of canonical Wnt signaling through a mechanism of facilitating LRP5/6 phosphorylation. Here, we resolved the crystal structure of the N-terminal homologous region 1 (HR1) domain of human Caprin-2. HR1 domain is so far only observed in Caprin-2 and its homologous protein Caprin-1, and the function of this domain remains largely mysterious. Here, the structure showed that HR1 domain of human Caprin-2 forms a homo-dimer and exhibits an overall structure roughly resembling the appearance of a pair of scissors. Moreover, we found that residues R200 and R201, which located at a basic cluster within the N-terminal "blades" region, are critical for Caprin-2's localization to the plasma membrane. In line with this, mutations targeting these two residues decrease Caprin-2's activity in the canonical Wnt signaling. Overall, we characterized a previously unknown "scissors"-like structure of the full-length HR1 domain and revealed its function in mediating Caprin-2's localization to the plasma membrane.

LncRNAs as nodes for the cross-talk between autophagy and Wnt signaling in pancreatic cancer drug resistance

Pancreatic cancer is a malignancy with high mortality. In addition to the few symptoms until the disease reaches an advanced stage, the high fatality rate is attributed to its rapid development, drug resistance and lack of appropriate treatment. In the selection and research of therapeutic drugs, gemcitabine is the first-line drug for pancreatic cancer. Solving the problem of gemcitabine resistance in pancreatic cancer will contribute to the progress of pancreatic cancer treatment. Long non coding RNAs (lncRNAs), which are RNA transcripts longer than 200 nucleotides, play vital roles in cellular physiological metabolic activities. Currently, our group and others have found that some lncRNAs are aberrantly expressed in pancreatic cancer cells, which can regulate the process of cancer through autophagy and Wnt/β-catenin pathways simultaneously and affect the sensitivity of cancer cells to therapeutic drugs. This review presents an overview of the recent evidence concerning the node of lncRNA for the cross-talk between autophagy and Wnt/β-catenin signaling in pancreatic cancer, together with the practicability of lncRNAs and the core regulatory factors as targets in therapeutic resistance.

The role of cyclin Y in normal and pathological cells

The family protein of cyclins, as well as cyclin-dependent kinases (CDKs) cooperating with them, are broadly researched, as a matter of their dysfunction may lead to tumor transformation. Cyclins are defined as key regulators that have a controlling function of the mammalian nuclear cell divides. Cyclin Y (CCNY) is a recently characterized member of the cyclin family and was first identified from the human testis cDNA library. It is an actin-binding protein acting through decreased actin dynamics at a steady state and during glycine-induced long-term potentiation (LTP) and involves the inhibition of cofilin activation. What is more, CCNY is a positive regulatory subunit of the CDK14/PFTK1 complexes affected by the activation of the Wnt signaling pathway in the G2/M phase by recruiting CDK14/PFTK1 to the plasma membrane and promoting phosphorylation of LRP6. The expression of CCNY has been significantly mentioned within the cell migration and invasion activity both in vivo and in vitro. The aim of this review is evaluation of the expression of CCNY in the physiology processes and compare the expression of this protein in cancer cells, taking into account the impact of the level of expression on tumor progression.

Molecular mechanisms of microRNA-216a during tumor progression

MicroRNAs (miRNAs) as the members of non-coding RNAs family are involved in post-transcriptional regulation by translational inhibiting or mRNA degradation. They have a critical role in regulation of cell proliferation and migration. MiRNAs aberrations have been reported in various cancers. Considering the importance of these factors in regulation of cellular processes and their high stability in body fluids, these factors can be suggested as suitable non-invasive markers for the cancer diagnosis. MiR-216a deregulation has been frequently reported in different cancers. Therefore, in the present review we discussed the molecular mechanisms of the miR-216a during tumor progression. It has been reported that miR-216a mainly functioned as a tumor suppressor through the regulation of signaling pathways and transcription factors. This review paves the way to suggest the miR-216a as a probable therapeutic and diagnostic target in cancer patients.

Toxicological impacts and likely protein targets of bisphenol a in Paramecium caudatum

Bisphenol A (BPA) is a widely used plasticizer agent and a well-known ubiquitous endocrine disruptor, which is frequently associated with a series of reproductive, developmental, and transgenerational effects over wildlife, livestocks, and humans. Although extensive toxicological data is available for metazoans, the impact of BPA over unicellular eukaryotes, which represents a considerable proportion of eukaryotic diversity, remains largely overlooked. Here, we used acute end-point toxicological assay and an inverted virtual-screening (IVS) approach to evaluate cellular impairments infringed by BPA over the cosmopolitan ciliated protist, Paramecium caudatum. Our data indicate a clear time-dependent effect over P. caudatum survival, which seems to be a consequence of disruptions to multiple core cellular functions, such as DNA and cell replication, transcription, translation and signaling pathways. Finally, the use of this ciliate as a biosensor to monitor BPA within environments and the relevance of bioinformatic methods to leverage our current knowledge on the impacts of emerging contaminants to biological systems are discussed.

Regulation of the Low-Density Lipoprotein Receptor-Related Protein LRP6 and Its Association With Disease: Wnt/β-Catenin Signaling and Beyond

Wnt signaling plays crucial roles in development and tissue homeostasis, and its dysregulation leads to various diseases, notably cancer. Wnt/β-catenin signaling is initiated when the glycoprotein Wnt binds to and forms a ternary complex with the Frizzled and low-density lipoprotein receptor-related protein 5/6 (LRP5/6). Despite being identified as a Wnt co-receptor over 20 years ago, the molecular mechanisms governing how LRP6 senses Wnt and transduces downstream signaling cascades are still being deciphered. Due to its role as one of the main Wnt signaling components, the dysregulation or mutation of LRP6 is implicated in several diseases such as cancer, neurodegeneration, metabolic syndrome and skeletal disease. Herein, we will review how LRP6 is activated by Wnt stimulation and explore the various regulatory mechanisms involved. The participation of LRP6 in other signaling pathways will also be discussed. Finally, the relationship between LRP6 dysregulation and disease will be examined in detail.

The Candidate IBD Risk Gene CCNY Is Dispensable for Intestinal Epithelial Homeostasis

The CCNY gene, which encodes cyclin Y, has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Cyclin Y promotes Wnt/β-catenin signaling and autophagy, which are critical for intestinal epithelial cell (IEC) homeostasis, and may thereby contribute to wound repair in colitis. However, whether cyclin Y has an essential function in IECs is unknown. We, therefore, investigated the epithelial injury response and mucosal regeneration in mice with conditional knock-out of Ccny in the intestinal epithelium. We observed that Ccny-deficient mice did not exhibit any differences in cell proliferation and disease activity compared to wild-type littermates in the dextran sulfate sodium (DSS) colitis model. Complementary in vitro experiments showed that loss of CCNY in model IECs did not affect Wnt signaling, cell proliferation, or autophagy. Additionally, we observed that expression of the cyclin-Y-associated cyclin-dependent kinase (CDK) 14 is exceedingly low specifically in IEC. Collectively, these results suggest that cyclin Y does not contribute to intestinal epithelial homeostasis, possibly due to low levels of specific CDKs in these cells. Thus, it is unlikely that CCNY mutations are causatively involved in IBD pathogenesis.

Parsing β-catenin's cell adhesion and Wnt signaling functions in malignant mammary tumor progression

During malignant progression, epithelial cancer cells dissolve their cell-cell adhesion and gain invasive features. By virtue of its dual function, β-catenin contributes to cadherin-mediated cell-cell adhesion, and it determines the transcriptional output of Wnt signaling: via its N terminus, it recruits the signaling coactivators Bcl9 and Pygopus, and via the C terminus, it interacts with the general transcriptional machinery. This duality confounds the simple loss-of-function analysis of Wnt signaling in cancer progression. In many cancer types including breast cancer, the functional contribution of β-catenin's transcriptional activities, as compared to its adhesion functions, to tumor progression has remained elusive. Employing the mouse mammary tumor virus (MMTV)-PyMT mouse model of metastatic breast cancer, we compared the complete elimination of β-catenin with the specific ablation of its signaling outputs in mammary tumor cells. Notably, the complete lack of β-catenin resulted in massive apoptosis of mammary tumor cells. In contrast, the loss of β-catenin's transcriptional activity resulted in a reduction of primary tumor growth, tumor invasion, and metastasis formation in vivo. These phenotypic changes were reflected by stalled cell cycle progression and diminished epithelial-mesenchymal transition (EMT) and cell migration of breast cancer cells in vitro. Transcriptome analysis revealed subsets of genes which were specifically regulated by β-catenin's transcriptional activities upon stimulation with Wnt3a or during TGF-β-induced EMT. Our results uncouple the signaling from the adhesion function of β-catenin and underline the importance of Wnt/β-catenin-dependent transcription in malignant tumor progression of breast cancer.

Cytoplasmic Localization Isoform of Cyclin Y Enhanced the Metastatic Ability of Lung Cancer via Regulating Tropomyosin 4

Cyclin Y (CCNY) is a novel cyclin and highly conserved in metazoan species. Previous studies from our and other laboratory indicate that CCNY play a crucial role in tumor progression. There are two CCNY isoform which has different subcellular distributions, with cytoplasmic isoform (CCNYc) and membrane distribution isoform (CCNYm). However, the expression and function of CCNY isoforms is still unclear. We firstly found CCNYc was expressed in natural lung cancer tissue and cells through the subcellular distribution. Co-IP and immunofluorescence showed that both CCNYm and CCNYc could interact with PFTK1. Further studies illustrated that CCNYc but not CCNYm enhanced cell migration and invasion activity both in vivo and vitro. The function of CCNYc could be inhibited by suppression of PFTK1 expression. In addition, our data indicated that tropomyosin 4 (TPM4), a kind of actin-binding proteins, was down-regulated by suppression of CCNY. F-actin assembly could be controlled by CCNYc as well as PFTK1 and TPM4. As a result, CCNY was mainly expressed in lung cancer. CCNYc could promote cell motility and invasion. It indicated that CCNYc/PFTK1 complex could promote cell metastasis by regulating the formation of F-actin via TPM4.

A Novel Transcriptome Integrated Network Approach Identifies the Key Driver lncRNA Involved in Cell Cycle With Chromium (VI)-Treated BEAS-2B Cells

Hexavalent chromium [Cr(VI)] is a well-known occupational carcinogen, but the mechanisms contributing to DNA damage and cell cycle alternation have not been fully characterized. To study the dose-response effects of Cr(VI) on transcription, we exposed BEAS-2B cells to Cr(VI) at concentrations of 0.2, 0.6, and 1.8 μmol/L for 24 h. Here, we identified 1,484 differentially expressed genes (DEGs) in our transcript profiling data, with the majority of differentially expressed transcripts being downregulated. Our results also showed that these DEGs were enriched in pathways associated with the cell cycle, including DNA replication, chromatin assembly, and DNA repair. Using the differential expressed genes related to cell cycle, a weighted gene co-expression network was constructed and a key mRNA-lncRNA regulation module was identified under a scale-free network with topological properties. Additionally, key driver analysis (KDA) was applied to the mRNA-lncRNA regulation module to identify the driver genes. The KDA revealed that ARD3 (FDR = 1.46 × 10^–22), SND1 (FDR = 5.24 × 10^–8), and lnc-DHX32-2:1 (FDR = 1.43 × 10^–17) were particularly highlighted in the category of G2/M, G1/S, and M phases. Moreover, several genes we identified exhibited great connectivity in our causal gene network with every key driver gene, including CDK14, POLA1, lnc-NCS1-2:1, and lnc-FOXK1-4:1 (all FDR < 0.05 in those phases). Together, these results obtained using mathematical approaches and bioinformatics algorithmics might provide potential new mechanisms involved in the cytotoxicity induced by Cr.

CCNY Accelerates Cylcin E Expression to Regulate the Proliferation of Laryngeal Carcinoma Cells via MEK/ERK Signaling Pathway

Background

Laryngeal carcinoma is a common cancer among head and neck tumors, accounting for 0.5–1% new cancer cases or deaths of all tumors throughout the body. Despite improvements in diagnostic and therapy, the prognosis of laryngeal carcinoma patients still remains poor. Thus, it is very important to identify the biomarkers involved in the molecular pathogenesis of laryngeal carcinoma. Cyclin Y (CCNY) is a conserved cell cycle regulator that acts as a growth factor in many cancers. The clinical significance of CCNY in laryngeal carcinoma remains unknown. The function of CCNY in laryngocarcinoma was studied in this paper.

Materials and Methods

CCNY knock-out cells were constructed by CRISPR/CAS9 technique. CCNY overexpression cells were also constructed based on CCNY knock-out cells. Cell growth ability was detected by MTS assay, high-content cell analysis, colony formation assays, and anchorage-independent growth assays. The protein levels in laryngocarcinoma cells were determined by Western blot. The role of CCNY in cell cycle progression was evaluated by flow cytometry.

Results

CCNY knock-out cells and CCNY up-regulation cell models were obtained successfully. Suppression of CCNY expression inhibited Hep2 cell growth. Cell growth was enhanced by the up-regulation of CCNY. The percentage of cells in G1 phase was altered when CCNY expression was down-regulated or up-regulated. The phosphorylation level of MEK and ERK as well as cyclin E protein level was also regulated by the expression level of CCNY.

Conclusion

In laryngocarcinoma cell line Hep2 cells, cell proliferation was controlled by CCNY. The expression of CCNY was involved in the cell cycle progress of Hep2 cells. It indicated that CCNY could promote cell growth by activating MEK/ERK/cyclin E signaling pathway.

Upregulation of miR-1825 inhibits the progression of glioblastoma by suppressing CDK14 though Wnt/β-catenin signaling pathway

BACKGROUND

Mounting evidences displayed that miRNAs play crucial roles in tumor initiation and development. However, the regulation and relevant mechanism of miR-1825 in glioblastoma (GBM) remain unclear.

METHODS

qRT-PCR was used to detect miR-1825 and CDK14 mRNA expression. Western blot was applied for testing protein levels (VEGF, E-cadherin, N-cadherin, vimentin, β-catenin, c-myc, p-c-Jun). MTT and transwell assays were used for detecting GBM cell progression, including cell viability, migration, and invasion.

RESULTS

The results showed that miR-1825 was decreased in GBM tissue specimens by qRT-PCR and it was confirmed as a prognostic marker of GBM by Kaplan-Meier survival analysis. Moreover, we also found that miR-1825 upregulation suppressed GBM cell viability, tumor growth, invasion, and migration. Furthermore, CDK14 was first identified as the direct target of miR-1825 by Luciferase reporter assay. CDK14 acted as an oncogene in GBM development by immunohistochemistry. In addition, Western blot analysis demonstrated that miR-1825 regulated Wnt/β-catenin signaling pathway in GBM development.

CONCLUSION

In conclusion, miR-1825 upregulation suppressed GBM progression by targeting CDK14 through Wnt/β-catenin pathway.

WNT Signaling in Tumors: The Way to Evade Drugs and Immunity

WNT/β-catenin signaling is involved in many physiological processes. Its implication in embryonic development, cell migration, and polarization has been shown. Nevertheless, alterations in this signaling have also been related with pathological events such as sustaining and proliferating the cancer stem cell (CSC) subset present in the tumor bulk. Related with this, WNT signaling has been associated with the maintenance, expansion, and epithelial-mesenchymal transition of stem cells, and furthermore with two distinctive features of this tumor population: therapeutic resistance (MDR, multidrug resistance) and immune escape. These mechanisms are developed and maintained by WNT activation through the transcriptional control of the genes involved in such processes. This review focuses on the description of the best known WNT pathways and the molecules involved in them. Special attention is given to the WNT cascade proteins deregulated in tumors, which have a decisive role in tumor survival. Some of these proteins function as extrusion pumps that, in the course of chemotherapy, expel the drugs from the cells; others help the tumoral cells hide from the immune effector mechanisms. Among the WNT targets involved in drug resistance, the drug extrusion pump MDR-1 (P-GP, ABCB1) and the cell adhesion molecules from the CD44 family are highlighted. The chemokine CCL4 and the immune checkpoint proteins CD47 and PD-L1 are included in the list of WNT target molecules with a role in immunity escape. This pathway should be a main target in cancer therapy as WNT signaling activation is essential for tumor progression and survival, even in the presence of the anti-tumoral immune response and/or antineoplastic drugs. The appropriate design and combination of anti-tumoral strategies, based on the modulation of WNT mediators and/or protein targets, could negatively affect the growth of tumoral cells, improving the efficacy of these types of therapies.

Identification of key genes and pathways downstream of the β-catenin-TCF7L1 complex in pancreatic cancer cells using bioinformatics analysis

As a key component of the Wnt signaling pathway, the β-catenin-transcription factor 7 like 1 (TCF7L1) complex activates transcription and regulates downstream target genes that serve important roles in the pathology of pancreatic cancer. To identify associated key genes and pathways downstream of the β-catenin-TCF7L1 complex in pancreatic cancer cells, the current study used the gene expression profiles GSE57728 and GSE90926 downloaded from the Gene Expression Omnibus. GSE57728 is an array containing information regarding β-catenin knockdown and GSE90926 was developed by high throughput sequencing to provide information regarding TCF7L1 knockdown. Subsequently, differentially expressed genes (DEGs) were sorted separately and the shared 88 DEGs, including 37 upregulated and 51 downregulated genes, were screened. Clustering analysis of these DEGs was performed by heatmap analysis. Functional and pathway enrichment analyses were then performed using FunRich software and Database for Annotation, Visualization and Integrated Discovery, which revealed that the DEGs were predominantly enriched in terms associated with transport, transcription factor activity, and cytokine and chemokine mediated signaling pathway process. A DEG-associated protein-protein interaction (PPI) network, consisting of 58 nodes and 171 edges, was then constructed using Cytoscape software and the 15 genes with top node degrees were selected as the hub genes. Overall survival (OS) analysis of the 88 DEGs was performed and the relevant gene expression datasets were downloaded from The Cancer Genome Atlas. Consequently, three upregulated and seven downregulated genes were identified to be associated with prognosis. Furthermore, high expression levels of five downregulated genes, including CXCL5, CYP27C1, FUBP1, CDK14 and TRIM24, were associated with worse OS. In addition, CDK14 and TRIM24 were revealed as hub genes in the PPI network and both were confirmed to be involved in the Wnt/β-catenin pathway and phosphoinositide 3-kinase/Akt signaling pathway. Promoter analysis was also applied to the five downregulated DEGs associated with prognosis, which revealed that TCF7L1 may serve as a transcription factor of the DEGs. In conclusion, the genes and pathways identified in the current study may provide potential targets for the diagnosis and treatment of pancreatic cancer.

Discovery of Covalent CDK14 Inhibitors with Pan-TAIRE Family Specificity

Cyclin-dependent kinase 14 (CDK14) and other TAIRE family kinases (CDKs 15-18) are proteins that lack functional annotation but are frequent off-targets of clinical kinase inhibitors. In this study we develop and characterize FMF-04-159-2, a tool compound that specifically targets CDK14 covalently and possesses a TAIRE kinase-biased selectivity profile. This tool compound and its reversible analog were used to characterize the cellular consequences of covalent CDK14 inhibition, including an unbiased investigation using phospho-proteomics. To reduce confounding off-target activity, washout conditions were used to deconvolute CDK14-specific effects. This investigation suggested that CDK14 plays a supporting role in cell-cycle regulation, particularly mitotic progression, and identified putative CDK14 substrates. Together, these results represent an important step forward in understanding the cellular consequences of inhibiting CDK14 kinase activity.

MicroRNA-613 impedes the proliferation and invasion of glioma cells by targeting cyclin-dependent kinase 14

Increasing evidence has suggested that microRNAs (miRNAs) are critical regulators of tumorigenesis. MicroRNA-613 (miR-613) has recently been reported as a novel tumor-related miRNA that plays an important role in multiple cancers. However, the expression and functional significance of miR-613 in glioma remains unclear. In this study, we aimed to investigate the biological function of miR-613 in glioma. We found that miR-613 expression was frequently downregulated in glioma tissues and cell lines compared with normal controls. Overexpression of miR-613 impeded proliferation and colony formation and induced cell cycle arrest in G0/G1 phase, and also inhibited the invasive ability of glioma cells. By contrast, miR-613 inhibition had the opposite effects. Bioinformatic analysis and dual-luciferase reporter assays showed that miR-613 directly targets the 3'-untranslated region of cyclin-dependent kinase 14 (CDK14). Real-time quantitative PCR and Western blot analysis showed that CDK14 expression is negatively regulated by miR-613. In addition, miR-613 expression was inversely correlated with CDK14 expression in clinical glioma tissues. Moreover, overexpression of miR-613 decreased the protein expression of β-catenin and inhibited the activation of Wnt signaling. Importantly, the antitumor effects of miR-613 were significantly reversed by CDK14 overexpression. Overall, our results show that miR-613 inhibits glioma cell proliferation and invasion by downregulating CDK14, suggesting that miR-613 and CDK14 may serve as potential therapeutic targets for the treatment of glioma.

miR-216a inhibits osteosarcoma cell proliferation, invasion and metastasis by targeting CDK14

Osteosarcoma (OS) has emerged as the most common primary musculoskeletal malignant tumour affecting children and young adults. Cyclin-dependent kinases (CDKs) are closely associated with gene regulation in tumour biology. Accumulating evidence indicates that the aberrant function of CDK14 is involved in a broad spectrum of diseases and is associated with clinical outcomes. MicroRNAs (miRNAs) are crucial epigenetic regulators in the development of OS. However, the essential role of CDK14 and the molecular mechanisms by which miRNAs regulate CDK14 in the oncogenesis and progression of OS have not been fully elucidated. Here we found that CDK14 expression was closely associated with poor prognosis and overall survival of OS patients. Using dual-luciferase reporter assays, we also found that miR-216a inhibits CDK14 expression by binding to the 3′-untranslated region of CDK14. Overexpression of miR-216a significantly suppressed cell proliferation, migration and invasion in vivo and in vitro by inhibiting CDK14 production. Overexpression of CDK14 in the miR-216a-transfected OS cells effectively rescued the suppression of cell proliferation, migration and invasion caused by miR-216a. In addition, Kaplan–Meier analysis indicated that miR-216a expression predicted favourable clinical outcomes for OS patients. Moreover, miR-216a expression was downregulated in OS patients and was negatively associated with CDK14 expression. Overall, these data highlight the role of the miR-216a/CDK14 axis as a novel pleiotropic modulator and demonstrate the associated molecular mechanisms, thus suggesting the intriguing possibility that miR-216a activation and CDK14 inhibition may be novel and attractive therapeutic strategies for treating OS patients.