NEK2 plays an active role in Tumorigenesis and Tumor Microenvironment in Non-Small Cell Lung Cancer

Abnormal expression and dysfunction of Never-in-mitosis-A-related kinase 2 (NEK2) result in tumorigenesis. High levels of NEK2 are related to malignant progression, drug resistance, and poor prognosis. However, the relationship between NEK2 levels and the occurrence of non-small cell lung cancer (NSCLC) remains unknown. This study aimed to explore the impacts of NEK2 on the oncogenesis of NSCLC and the tumor microenvironment. Downregulation of NEK2 inhibited A549 and H1299 cell proliferation, migration, and invasion, blocking cell cycle at the G0/G1 phase. Loss of NEK2 inhibited the release of IL-10 from tumor cells, M2-like polarization of macrophages, angiogenesis, and vascular endothelial cell migration. Furthermore, NEK2 deficiency inhibited tumor growth in vivo. Taken together, NEK2 knockdown inhibited the occurrence and development of NSCLC, M2 polarization of macrophages, and angiogenesis. The abnormal expression of NEK2 might not only indicate tumor progression and patient prognosis but also serve as a potential molecular therapeutic target with great development prospects.

NEK2 regulates cellular proliferation and cabergoline sensitivity in pituitary adenomas

Objective: To identify critical roles played by NEK2 in prolactinomas and to clarify the corresponding underlying mechanisms. Methods: We performed RNA-seq on MMQ cell lines treated with the dopamine receptor agonist cabergoline (CAB) to identify genes involved in prolactinoma progression and dopamine receptor-agonist (DA) sensitivity. NEK2 was then selected for further study. The expression of NEK2 was examined using quantitative real-time PCR, western immunoblotting, and immunohistochemistry - both in pituitary adenomas (PA) and in normal pituitary tissue. We used gain-of-function and loss-of-function assays to explore the biologic roles of NEK2 in cell growth in vivo and in vitro. Co-immunoprecipitation was also used to detect the binding between NEK2 and USP7. Results: Herein, we reported that NEK2 was upregulated in prolactinomas, particularly dopamine-resistant prolactinomas. NEK2 overexpression significantly promoted pituitary tumor GH3 and MMQ cell proliferation, and it impaired cellular sensitivity to CAB. Conversely, knockdown of NEK2 inhibited GH3 and MMQ cell growth, and sensitized the cells to CAB. Mechanistically, NEK2 regulated cell proliferation via the Wnt-signaling pathway; and in addition, we demonstrated that USP7 interacted with, deubiquitylated, and stabilized NEK2. Conclusions: Collectively, our results suggest that NEK2 might be a potential therapeutic target for prolactinoma.

High expression of NEK2 promotes gastric cancer progression via activating AKT signaling

Never in mitosis gene A-related kinase 2 (NEK2) has been recognized as an oncogene involved in the initiation and progression of various human cancers. However, our knowledge is still lacking in regard to the function of NEK2 in gastric cancer, the most common cancer in Eastern Asia associated with poor prognosis. Therefore, in the present study, we investigated the association of NEK2 with gastric cancer. We found that the development of gastric cancer is associated with NEK2 overexpression, particularly in patients with large tumor size and lymph node metastasis. We also provided evidence that NEK2 overexpression binds to and inhibits protein phosphatase 1 (PP1), which subsequently activates AKT and the downstream oncogenic pathways. As a result, via AKT/HIF1α axis, the glucose metabolism is reprogrammed towards aerobic glycolysis to provide rapid energy for the growth of gastric cancer cells. Moreover, the autophagic activity is suppressed via AKT/mTOR axis, leading to impaired response to cancer treatment and enhanced cell survival. In contrast, inactivating AKT by NEK2 silencing decreases aerobic glycolysis and promotes autophagic cell death, which eventually inhibits the growth of gastric cancer cell. All these results revealed that NEK2 promotes gastric cancer progression via activating AKT-mediated signaling pathways, which expanded our knowledge on gastric cancer pathogenesis and also provided novel target for clinical treatment.

lncRNA SNHG1 Promotes Progression of Cervical Cancer Through miR-195/NEK2 Axis

Objective

Cervical cancer is a common gynecologic cancer, and no study has been reported on the way through which lncRNA SNHG1, miR-195 and NEK2 jointly affect cervical cancer cells (CCCs), so this paper will explore a new approach to the development of cervical cancer in this respect.

Methods

Altogether 72 cervical cancer tissues and 54 adjacent tissues were collected. qPCR was performed to quantify lncRNA SNHG1 and miR-195, whose expression vectors were constructed and then transfected into CCCs, so as to observe their effects on the cells. Western blotting (WB) was carried out to detect protein levels. MTT assay was conducted to detect cell activity. Flow cytometry was performed to detect cell apoptosis. Transwell was carried out to detect cell invasion and migration.

Results

The expression of lncRNA SNHG1 up-regulated while that of miR-195 down-regulated in CCCs. lncRNA SNHG1 regulated NEK2 through its targeted binding to miR-195. The down-regulation of lncRNA SNHG1 or the up-regulation of miR-195 led to the decrease of NEK2 and the reduction of cells’ activity, migration and invasion, also resulting in the increase of cell apoptosis. Rescue experiments showed that the down-regulation of miR-195 could offset the cell changes caused by lncRNA SNHG1.

Conclusion

lncRNA SNHG1 promotes the progression of cervical cancer through the miR-195/NEK2 axis, so lncRNA SNHG1, miR-195 and NEK2 may have potential values for diagnosing and treating cervical cancer.

Involvement of NEK2 and its interaction with NDC80 and CEP250 in hepatocellular carcinoma

BACKGROUND

NEK2 has an established involvement in hepatocellular carcinoma (HCC) but the roles of NEK2 and its interacting proteins in HCC have not been systematically explored.

METHODS

This study examined NEK2 and its interacting proteins in HCC based on multiple databases.

RESULTS

NEK2 mRNA was highly expressed in HCC tissues compared with normal liver tissues. The survival of HCC patients with high NEK2 mRNA expression was shorter than those with low expression. MAD1L1, CEP250, MAPK1, NDC80, PPP1CA, PPP1R2 and NEK11 were the interacting proteins of NEK2. Among them, NDC80 and CEP250 were the key interacting proteins of NEK2. Mitotic prometaphase may be the key pathway that NEK2 and its interacting proteins contributed to HCC pathogenesis. NEK2, NDC80 and CEP250 mRNAs were highly expressed in HCC tissues compared with normal liver tissues. The mRNA levels of NEK2 were positively correlated with those of NDC80 or CEP250. Univariate regression showed that NEK2, NDC80 and CEP250 mRNA expressions were significantly associated with HCC patients' survival. Multivariate regression showed that NDC80 mRNA expression was an independent predictor for HCC patients' survival. Methylations and genetic alterations of NEK2, NDC80 and CEP250 were observed in HCC samples. The alterations of NEK2, NDC80 and CEP250 genes were co-occurrence. Patients with high mRNA expression and genetic alterations of NEK2, NDC80 and CEP250 had poor prognosis.

CONCLUSIONS

NEK2 and its interacting proteins NDC80 and CEP250 play important roles in HCC development and progression and thus may be potentially used as biomarkers and therapeutic targets of HCC.

Targeting NEK2 impairs oncogenesis and radioresistance via inhibiting the Wnt1/β-catenin signaling pathway in cervical cancer

BACKGROUND

NEK2, a serine/threonine kinase involved in mitosis, has been found to function in chromosome instability, tumor progression and metastasis, but its role in cervical cancer radioresistance remains unknown.

METHODS

We detected the protein levels of NEK2 in cervical carcinoma tissues and paired paracarcinoma tissues by immunohistochemistry. The roles of NEK2 in oncogenesis were examined using cell growth and colony formation assays, EdU assay, apoptosis assay as well as in vivo mouse model. γ-H2AX and Rad51 foci formation, neutral comet assay and clonogenic cell survival assay were applied to determine the radiosensitivity of cervical cancer cells. RNA-seq was performed to identify the downstream effector of NEK2. The gene expression levels were measured by Real-time PCR.

RESULTS

We report that NEK2 protein level is overexpressed and correlated with the tumor stage and lymph node metastasis in cervical cancer tissues. Furthermore, we provided evidence that depletion of NEK2 impairs oncogenesis and enhances radiosensitivity in cervical cancer. Using RNA sequencing, we identify Wnt1 as a key downstream effector of NEK2. Knockdown of NEK2 downregulates the mRNA and protein levels of Wnt1, thereby inhibiting the activation of the Wnt/β-catenin signaling pathway. More importantly, the observed consequences induced by NEK2 depletion in cervical cancer cells can be partially rescued by Wnt1 overexpression.

CONCLUSIONS

Our results demonstrate that NEK2 activates the Wnt/β-catenin signaling pathway via Wnt1 to drive oncogenesis and radioresistance in cervical cancer, indicating that NEK2 may be a promising target for the radiosensitization of cervical cancer.

High Expression of NEK2 and PIM1, but Not PIM3, Is Linked to an Aggressive Phenotype of Bronchopulmonary Neuroendocrine Neoplasms

Dysregulations of the NEK2 and PIM1-3 kinase signaling axes have been implicated in the pathogenesis of several cancers, including those with a neuroendocrine phenotype. However, their impact on bronchopulmonary neuroendocrine neoplasms (BP-NENs) has not been investigated. The aim of this pilot study was to determine mRNA and protein levels of NEK2, PIM1, and PIM3 in a group of 49 patients with BP-NENs: 11 typical carcinoids, 5 atypical carcinoids, 11 large cell neuroendocrine carcinomas, 22 small cell lung carcinomas (SCLC). The expression was measured using TaqMan-based RT-PCR and immunohistochemistry. NEK2 and PIM1 mRNA levels were higher in the SCLC patients than in the other BP-NEN groups (p < 0.001). There was an association between NEK2 mRNA and protein expression (p = 0.023) and elevated NEK2 mRNA levels were related to reduced survival in BP-NEN patients (p = 0.015). Patients with higher PIM1 protein expression had also diminished survival comparing with those with weak or no PIM1 expression (p = 0.037). Elevated NEK2 and PIM1 expression were related to aggressive tumor phenotype and indirectly affected the overall survival of BP-NEN patients. Our pilot study supports the need for future investigation of the biological function of NEK2 and PIM1 in BP-NEN transformation to verify the clinical value of our findings.

High expression of NEK2 promotes lung cancer progression and drug resistance and is regulated by mutant EGFR

Activating mutations within the tyrosine kinase (TK) domain of epidermal growth factor receptor (EGFR) gene are observed in 10 ~ 30% of the patients diagnosed with non-small cell lung cancer (NSCLC), and are causally related to NSCLC initiation and progression. Treatments with tyrosine kinase inhibitors (TKIs) targeting EGFR significantly improve the outcome of NSCLC patients with EGFR mutation, but are often associated with drug resistance, which is the main cause of treatment failure and cancer relapse. In the present study, by screening the transcriptome of NSCLC patients, we found that EGFR activation is highly correlated with the up-regulation of mitotic regulator, never in mitosis gene A-related kinase 2 (NEK2). NEK2 overexpression is associated with the poor survival of EGFR-mutant patients but not the wild-type patients. Further functional validation revealed that EGFR mutation induces NEK2 expression by activating ERK signaling pathway. Elevated NEK2 level promotes the rapid cell cycle progression and favors the rapid proliferation of EGFR-mutant NSCLC cells. Of note, NEK2 overexpression also impairs the efficacy of TKI treatment via inhibiting apoptosis, while depleting NEK2 suppresses cell growth and restored the sensitivity of TKI in NSCLC cells. Taken together, our study revealed that NEK2 is an oncogene regulated by EGFR mutation and is involved in disease progression and treatment response in NSCLC with EGFR mutation. These findings will pave the road for optimizing personalized treatment strategies to overcome drug resistance and improve the prognosis of lung cancer patients with EGFR mutation.

Exosome-Derived miR-486-5p Regulates Cell Cycle, Proliferation and Metastasis in Lung Adenocarcinoma via Targeting NEK2

Objective

This study aimed to describe the mechanism of exosome-derived miR-486-5p underlying the cell cycle and progression in lung adenocarcinoma (LUAD).

Methods

Bioinformatics methods were applied for identifying the differentially expressed genes (DEGs) in the GEO-LUAD dataset, predicting where the potential target miRNA was expressed and exploring the corresponding downstream target mRNA. qRT-PCR was conducted to detect the levels of the target genes in cancer cells. Thereafter, a series of in vitro experiments were performed for cell activities evaluation, including CCK-8, EdU, colony formation assay and transwell. Besides, Western blot was applied to determine the protein levels of the migration and invasion-related factors (NEK2, E-cadherin, N-cadherin, Vimentin, MMP-2, and MMP-9). Dual-luciferase reporter gene assay was employed for validating the targeted relationship between the target genes. Furthermore, nude mouse transplantation tumor experiment was conducted to further validate the role of the target miRNA in tumor development, and immunohistochemistry was used for Ki67 detection and TUNEL was applied for cell apoptosis assay.

Results

miR-486-5p was observed to be enriched in serum exosomes, and seen to be significantly down-regulated in cancer tissues as well as in cancer serum exosomes. It was proven that exosomes could release miR-486-5p, thus regulating LUAD progression and affecting cell cycle. Moreover, NEK2 was identified as a target of miR-486-5p both in vivo and in vitro. Enrichment analysis revealed that NEK2 was mainly activated in cell cycle and mitosis-related pathways. Meanwhile, NEK2 was found to present significant difference in different TNM stages. Furthermore, rescue experiments indicated that the inhibitory effect of miR-486-5p overexpression on LUAD progression could be abrogated when miR-486-5p and NEK2 were simultaneously up-regulated.

Conclusion

Exosome-derived miR-486-5p is responsible for cell cycle arrest as well as the inhibition of cell proliferation and metastasis in LUAD via targeting NEK2.

NEK2 induces autophagy-mediated bortezomib resistance by stabilizing Beclin-1 in multiple myeloma

NEK2 is associated with drug resistance in multiple cancers. Our previous studies indicated that high NEK2 confers inferior survival in multiple myeloma (MM); thus, a better understanding of the mechanisms by which NEK2 induces drug resistance in MM is required. In this study, we discovered that NEK2 enhances MM cell autophagy, and a combination of autophagy inhibitor chloroquine (CQ) and chemotherapeutic bortezomib (BTZ) significantly prevents NEK2-induced drug resistance in MM cells. Interestingly, NEK2 was found to bind and stabilize Beclin-1 protein but did not affect its mRNA expression and phosphorylation. Moreover, autophagy enhanced by NEK2 was significantly prevented by knockdown of Beclin-1 in MM cells, suggesting that Beclin-1 mediates NEK2-induced autophagy. Further studies demonstrated that Beclin-1 ubiquitination is decreased through NEK2 interaction with USP7. Importantly, knockdown of Beclin-1 sensitized NEK2-overexpressing MM cells to BTZ in vitro and in vivo. In conclusion, we identify a novel mechanism whereby autophagy is activated by the complex of NEK2/USP7/Beclin-1 in MM cells. Targeting the autophagy signaling pathway may provide a promising therapeutic strategy to overcome NEK2-induced drug resistance in MM.

Circular RNA circPITX1 knockdown inhibits glycolysis to enhance radiosensitivity of glioma cells by miR-329-3p/NEK2 axis

Background

Numerous circular RNAs (circRNAs) have been recognized as vital modulators of human malignancies, including glioma. Whereas, the functional role of circRNA Pituitary Homeo Box 1 (circPITX1) in the radioresistance of glioma cells remains largely uncertain.

Methods

Quantitative real-time PCR (qRT-PCR) or western blot analysis was employed to examine the expression of circPITX1, microRNA (miR)-329-3p and NIMA-related kinase 2 (NEK2). 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) assay was used to determine cell viability. Glycolysis was assessed by commercial kits and western blot analysis. Colony formation assay was conducted to analyze cell survival and clonogenicity capacity. The relationship among circPITX1, miR-329-3p and NEK2 was confirmed via dual-luciferase reporter assay. The in vivo function of circPITX1 was evaluated by tumor xenograft assay.

Results

Expression of circPITX1 and NEK2 was up-regulated in glioma tissues and cells, while miR-329-3p exhibited reverse trend. CircPITX1 knockdown repressed viability, glycolysis and colony formation, but promoted radiosensitivity of glioma cells, as well as inhibited tumor growth in vivo. MiR-329-3p was a target miRNA of circPITX1 and miR-329-3p deficiency reversed knockdown of circPITX1-mediated glycolysis inhibition and radioresistance reduction. MiR-329-3p exerted inhibitory effects on glycolysis and radioresistance of glioma cells by targeting NEK2. CircPITX1 facilitated NEK2 expression by sponging miR-329-3p. Glycolytic inhibitor 2-deoxy-d-glucose (2-DG) disposition weakened the promoted impact on glycolysis caused by circPITX1.

Conclusion

CircPITX1 knockdown reduced glycolysis to contribute to radiosensitivity in glioma through miR-329-3p/NEK2 axis, providing a possible mechanism of circPITX1 in the development of glioma.

Comparative phosphorylation map of Dishevelled 3 links phospho-signatures to biological outputs

Background

Dishevelled (DVL) is an essential component of the Wnt signaling cascades. Function of DVL is controlled by phosphorylation but the molecular details are missing. DVL3 contains 131 serines and threonines whose phosphorylation generates complex barcodes underlying diverse DVL3 functions. In order to dissect the role of DVL phosphorylation we analyzed the phosphorylation of human DVL3 induced by previously reported (CK1ε, NEK2, PLK1, CK2α, RIPK4, PKCδ) and newly identified (TTBK2, Aurora A) DVL kinases.

Methods

Shotgun proteomics including TiO₂ enrichment of phosphorylated peptides followed by liquid chromatography tandem mass spectrometry on immunoprecipitates from HEK293T cells was used to identify and quantify phosphorylation of DVL3 protein induced by 8 kinases. Functional characterization was performed by in-cell analysis of phospho-mimicking/non-phosphorylatable DVL3 mutants and supported by FRET assays and NMR spectroscopy.

Results

We used quantitative mass spectrometry and calculated site occupancies and quantified phosphorylation of > 80 residues. Functional validation demonstrated the importance of CK1ε-induced phosphorylation of S268 and S311 for Wnt-3a-induced β-catenin activation. S630–643 cluster phosphorylation by CK1, NEK2 or TTBK2 is essential for even subcellular distribution of DVL3 when induced by CK1 and TTBK2 but not by NEK2. Further investigation showed that NEK2 utilizes a different mechanism to promote even localization of DVL3. NEK2 triggered phosphorylation of PDZ domain at S263 and S280 prevents binding of DVL C-terminus to PDZ and promotes an open conformation of DVL3 that is more prone to even subcellular localization.

Conclusions

We identify unique phosphorylation barcodes associated with DVL function. Our data provide an example of functional synergy between phosphorylation in structured domains and unstructured IDRs that together dictate the biological outcome.

NEK2 promotes proliferation, migration and tumor growth of gastric cancer cells via regulating KDM5B/H3K4me3

The mechanisms of how Never in Mitosis (NIMA) Related Kinase 2 (NEK2) coordinates altered signaling to malignant gastric cancer (GC) transformation remain unclear. Overexpression of NEK2 and KDM5B were observed in GC cell lines with high sensitivity to NEK2 inhibitors. Here we investigated the biological behaviors of NEK2 and the possible mechanisms of regulative effects of NEK2 on KDM5B in GC cell lines both in vitro and in vivo. The results showed that NEK2 and KDM5B were highly expressed in most of the 10 GC cell lines. NEK2 knockdown in MGC-803 cells led to suppression of cell proliferation and migration in vitro and tumor growth in vivo, while NEK2 overexpression in BGC-823 cells exhibited the reverse biological effect. When NEK2 was inhibited by NEK2 inhibitors or shNEK2, cellular KDM5B level decreased and H3K4me3 level increased, while overexpression of NEK2 resulted in enhanced KDM5B expression and decreased H3K4me3 level. Though direct interaction between NEK2 and KDM5B was excluded, NEK2 could regulate KDM5B/H3K4me3 expression through β-catenin/Myc both in vitro and in vivo, which was double confirmed by c-myc and KDM5B inhibitor experiments. Taken together, our study showed that NEK2 was highly expressed in GC cell lines and related to promoting cell proliferation, migration and tumor growth. A NEK2/β-catenin/Myc/KDM5B/H3K4me3 signaling pathway may contribute to the important carcinogenic role of NEK2-mediated malignant behaviors in GC.

NEK2 Is an Effective Target for Cancer Therapy With Potential to Induce Regression of Multiple Human Malignancies

Cancer is characterized by uncontrolled cell proliferation due to the aberrant activity of various proteins. Cell cycle-related proteins are thought to be important in several functions, such as proliferation, invasion and drug resistance in human malignancies. Never in mitosis gene A-related kinase 2 (NEK2) is a cell cycle-related protein. NEK2 is highly expressed in various tumor types and cancer cell lines. NEK2 expression is correlated with rapid relapse and poor outcome in multiple cancer types. Several researchers have demonstrated that NEK2 inhibition results in anticancer effects against many types of cancers, both in vitro and in vivo. Recent research strongly indicates the advantages of NEK2-targeted therapy for cancer. This review focuses on the current understanding of NEK2 in cancer and the rationale of a xenograft cancer model for cancer treatment. A possible therapeutic strategy, such as inhibitor and nucleic acid medicine targeting of NEK2, is also discussed.

microRNA-138 induces cell survival and reduces WNT/β-catenin signaling of osteoarthritis chondrocytes through NEK2

Osteoarthritis (OA) is a degenerative joint disease characterized by joint pain, stiffness, and function degeneration with high incidence. Recent studies have been inspired based on the association between microRNAs (miRs) and therapeutic research of OA. Hence, the present study evaluates the effects of miR-138 on chondrocyte proliferation, differentiation, and apoptosis through the WNT/β-catenin signaling pathway in mice with OA by binding to NIMA-related kinase 2 (NEK2). Appropriate dataset was selected from the Gene Expression Omnibus database, and differentially expressed genes and potential miRNAs that could regulate NEK2 were explored. A mouse model of OA was established. The expressions of miR-138, NEK2, β-catenin, GSK3β, Bcl-2, Bcl-2-associated X protein (Bax), p53, MMP-13, Col2, and Aggrecan and the phosphorylation levels of β-catenin were determined by the reverse transcription quantitative polymerase chain reaction and Western blot analysis. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and flow cytometry were employed to detect cell proliferation and apoptosis, respectively. The potential functional role of NEK2 was revealed to be related to the WNT/β-catenin signaling pathway, and miR-138 was the putative regulator of NEK2. miR-138 expression was downregulated while expressions of NEK2 and β-catenin as well as the phosphorylation levels of β-catenin were upregulated in mice with OA. The chondrocytes treated with miR-138 mimic and siRNA-NEK2 exhibited reduced expressions of NEK2, β-catenin, MMP-13, Bax, and p53 and elevated expressions of Col2, Aggrecan, and Bcl-2 as well as phosphorylation levels of β-catenin along with enhanced chondrocytes' proliferation and suppressed cell apoptosis. Overexpression of miR-138 induces cell survival and reduces WNT/β-catenin signaling of OA chondrocytes through NEK2. © 2019 IUBMB Life, 71(9):1355-1366, 2019.

Cancer upregulated gene (CUG)2 elevates YAP1 expression, leading to enhancement of epithelial-mesenchymal transition in human lung cancer cells

Although our previous studies have showed that a novel oncogene, cancer upregulated gene (CUG)2 induced epithelial-mesenchymal transition (EMT), the detailed molecular mechanism remains unknown. Because several lines of evidence documented that Yes-Associated Protein (YAP)1 is closely associated with cancer stem cell (CSC)-like phenotypes including EMT, stemness, and drug resistance, we wondered if YAP1 is involved in CUG2-induced EMT. We herein found that the overexpression of CUG2 increased YAP1 expression at the transcriptional as well as protein levels. Chromatin immunoprecipitation assay revealed that the elevated YAP1 transcripts are attributed to c-Jun and AP2 bindings to the YAP1 promoter. Akt and MAPK kinases including ERK, JNK, and p38 MAPK enhanced the level of YAP1 protein. In spite of a close relationship between β-catenin and YAP1, not β-catenin but NEK2 played the role in increasing YAP1 expression. Silencing YAP1 inhibited CUG2-induced cell migration and invasion. N-cadherin and vimentin expressions were decreased during YAP1 knockdown. The suppression of YAP1 diminished TGF-β transcriptional activity and expression as well as phosphorylation level of Smad2 and Twist protein. Conversely, LY2109761 or Smad2 siRNA treatment reduced YAP1 protein levels, indicating a close interplay between YAP1 and TGF-β signaling. Taken together, we suggest that CUG2 induces up-regulation of YAP1 expression, leading to enhancing CUG2-induced EMT via a close crosstalk between YAP1 and TGF-β signaling.

NIMA-related kinase 2 overexpression is associated with poor survival in cancer patients: a systematic review and meta-analysis

Objective

NIMA-related kinase 2 (NEK2) has been reported to be overexpressed in various types of cancer and correlated with poor prognosis. The role(s) of NEK2 in cancer, however, is still uncertain. The aim of this study was to evaluate the prognostic value of NEK2 in human tumors.

Methods

A comprehensive literature search was performed for PubMed, Embase, Web of Science, and CNKI databases, and eligible studies were included based on the inclusion and exclusion criteria. A meta-analysis of the included studies was then carried out.

Results

Fifteen studies with 3,280 cancer patients were included in the present meta-analysis. All publications were of moderate to high quality, and had no significant heterogeneity (I^2=46%, P=0.03) or publication bias was discovered. The results showed that a high NEK2 level was associated with shorter overall survival (OS) in patients with various types of cancers (pooled HR=1.72, 95% CI 1.49–2.00, P<0.00001). However, the disease-free survival (DFS) had no significant association with NEK2 level (HR=1.13, 95% CI: 0.29–4.38, P=0.85). In the subgroup analyses, high NEK2 level was correlated with an increased risk of poor OS in patients with hepatocellular carcinoma (HR=1.62, 95% CI: 1.25–2.10, P=0.02) and lung cancer (HR=2.18, 95% CI: 1.40–3.38, P=0.0005). However, other factors, including sample size, follow-up period, HR estimation method, and country, also affect the association between NEK2 expression and OS. Analysis of clinicopathological parameters further showed that increased NEK2 level was correlated with younger age, male gender, better tumor differentiation, and lower number of tumor nodules.

Conclusion

The results of this study indicated that increased expression of NEK2 was associated with unfavorable survival of cancer patients and that NEK2 could be used as a prognostic predictor for cancers.

The Prognostic Significance of NEK2 in Hepatocellular Carcinoma: Evidence from a Meta-Analysis and Retrospective Cohort Study

BACKGROUND/AIMS

Numerous studies have shown that NIMA-related kinase 2 (NEK2) expression in hepatocellular carcinoma (HCC) tissue is associated with survival and clinicopathological features; however, the evidence remains inconclusive. Thus, we aimed to further explore the prognostic and clinicopathological significance of NEK2 expression in HCC using a two-part study consisting of a retrospective cohort study and a meta-analysis.

METHODS

In the cohort study, NEK2 expression in 206 HCC samples and adjacent normal liver tissues was detected by immunohistochemistry (IHC). Patients were divided into a high NEK2 expression group and a low NEK2 expression group by the median value of the immunohistochemical scores. The Kaplan-Meier method with the log-rank test was used to analyze survival outcomes in the two groups, and multivariate analysis based on Cox proportional hazard regression models was applied to identify independent prognostic factors. In the meta-analysis, eligible studies were searched in PubMed, EMBASE, Web of Science, and CNKI databases. STATA version 12.0 (Stata Corporation, College Station, TX) was used for statistical analyses.

RESULTS

The IHC results of our cohort study showed higher NEK2 expression in HCC tissues compared with adjacent normal liver tissues. Multivariate analysis revealed that high NEK2 expression was an independent risk factor for poor overall survival (OS) [hazard ratio (HR) = 1.763; 95% CI, 1.060-2.935; P = 0.029] and disease-free survival (DFS) [hazard ratio (HR) = 1.687; 95% CI, 1.102-2.584; P = 0.016] in HCC patients. A total of 11 studies with 1,698 patients were enrolled in the meta-analysis, consisting of 10 studies from the database search and our cohort study. The pooled results revealed that high NEK2 expression correlated closely with poor OS among HCC patients (HR = 1.47; 95% CI, 1.21-1.80; P < 0.01), and DFS/recurrence-free survival (RFS) (HR = 1.92; 95% CI, 1.41-2.63; P < 0.01). Additionally, our meta-analysis also showed that the proportion of HCC patients with high NEK2 expression was greater in the group with larger tumors (> 5 cm) than in the group with smaller tumors (≤ 5 cm) [odds ratio (OR) = 2.02; 95% CI, 1.13-3.64; P < 0.01).

CONCLUSION

Our study demonstrated that high NEK2 expression is a risk factor for poor survival in HCC patients. More prospective, homogeneous, and multiethnic studies are required to validate our findings.

CircRNA circPDSS1 promotes the gastric cancer progression by sponging miR-186-5p and modulating NEK2

The aim of this study is to investigate the regulatory mechanism of circPDSS1/miR-186-5p/NEK2 axis on the viability and proliferation in gastric cancer (GC) cell line. Differentially expressed circRNAs, miRNAs, and mRNAs in GC tissues and paracarcinoma tissues were analyzed using gene chips GSE83521, GSE89143, and GSE93415. Then, the expression of circPDSS1, miR-186-5p, and NEK2 was analyzed via quantitative real-time polymerase chain reaction (qRT-PCR). Survival analysis was adopted to explore the association between the circPDSS1 expression and the prognosis of GC. The effect of circPDSS1 on GC cell cycle and apoptosis was verified with the flow cytometry. Targeting relationships among circPDSS1, miR-186-5p, and NEK2 were predicted via bioinformatics analysis and demonstrated by the dual-luciferase reporter assay. Our results showed that circPDSS1 and NEK2 were high-expressed whereas miR-186-5p was low-expressed in GC tissues and cells. CircPDSS1 promoted GC cell cycle and inhibited apoptosis by sponging miR-186-5p, while miR-186-5p inhibited cell cycle and promoted apoptosis by targeting NEK2. Thus, circPDSS1 acts as a tumor promoter by regulating miR-186-5p and NEK2, which could be a potential biomarker and therapeutic target for the management of GC.

Prognostic value of NEK2 overexpression in digestive system cancers: a meta-analysis and systematic review

Background and objective

Many studies have reported that NEK2 is overexpressed in digestive system cancers (DSCs) and is also correlated with patient survival. We performed a meta-analysis to comprehensively evaluate the prognostic role of NEK2 expression in DSCs.

Materials and methods

A comprehensive literature search was performed using PubMed, EMBASE, and Web of Science. Synthesized hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the influence of NEK2 overexpression on the prognosis and clinicopathological features of patients with DSCs.

Results

A total of 13 studies involving 1,917 patients was included. Overall, patients with high NEK2 expression had poorer overall survival (HR =1.45; 95% CI: 1.15–1.83; P=0.002) and disease-free survival/recurrence-free survival (HR =2.28; 95% CI: 1.54–3.37; P<0.0001). Furthermore, subgroup analysis also suggested that elevated NEK2 expression was associated with poorer overall survival in patients with hepatocellular carcinoma (HR =1.45; 95% CI: 1.05–2.00; P=0.02) and colorectal cancer (HR =2.03; 95% CI: 1.16–3.54; P=0.01). Additionally, NEK2 overexpression was also associated with pretreatment serum AFP level (OR =1.79; 95% CI: 1.23–2.61; P<0.01) and portal vein thrombosis (OR =2.74; 95% CI: 1.22–6.17; P=0.01) in hepatocellular carcinoma.

Conclusion

NEK2 might act as a useful prognostic predictor and a potential therapeutic target in DSCs. However, multicenter homogeneous studies with larger sample sizes are needed to further confirm our findings owing to some limitations in our meta-analysis.

High NEK2 confers to poor prognosis and contributes to cisplatin-based chemotherapy resistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a common malignant tumor in southern China and Southeast Asia, but the molecular mechanism of its pathogenesis is poorly understood. Our previous work demonstrated that NEK2 is overexpressed in multiple cancers. However, how NEK2 involves in NPC development remains to be elucidated. In this study, we firstly identified NEK2, located at +1q32‐q33, a late event in NPC pathogenesis, overexpressed in the stage III‐IV and paired sequential recurrent patients with NPC by immunohistochemistry. Furthermore, Kaplan‐Meier analysis indicated high NEK2 conferred an inferior overall survival in NPC. In addition, cisplatin experiments with cell counting kit‐8, colony formation, and a xenograft mice model of NPC demonstrated that NEK2 contributed to proliferation and cisplatin resistance in vitro and in vivo. On the contrary, downregulation of NEK2 by short hairpin RNA inhibited NPC cell growth and increased the sensitivity of cisplatin treatment in vitro. Thus, increased expression of NEK2 protein could not be predicted for poor survival but used as a novel biomarker for recurrence of NPC. Targeting NEK2 has the potential to eradicate the cisplatin‐based chemotherapy resistant NPC cells.

Preclinical activity of MBM-5 in gastrointestinal cancer by inhibiting NEK2 kinase activity

NEK2 is a conserved mitotic regulator critical for cell cycle progression. Aberrant expression of NEK2 has been found in a variety of human cancers, making it an attractive molecular target for the design of novel anticancer therapeutics. In the present study, we have identified a novel compound MBM-5, which was found to bind to NEK2 with high affinity by docking simulations study. MBM-5 potently inhibited NEK2 kinase activity in vitro in a concentration-dependent manner. MBM-5 also suppressed cellular NEK2 kinase activity, as evidenced by the decreased phosphorylation of its substrate Hec1 on S165 in a concentration- and time-dependent manner. This inhibition impeded mitotic progression by inducing chromosome segregation defects and cytokinesis failure; therefore leading to accumulation of cells with ≥4N DNA content, which finally underwent apoptosis. More importantly, MBM-5 treatment effectively suppressed the tumor growth of human gastric and colorectal cancer cells xenografts. Taken together, we demonstrated that MBM-5 effectively inhibited the kinase activity of NEK2 and showed a potential application in anti-cancer treatment regimens.

MicroRNA-128 promotes apoptosis in lung cancer by directly targeting NIMA-related kinase 2

Background

MicroRNA‐128 (miR‐128) serves as a regulator by inducing cancer cell apoptosis, differentiation, the epithelial‐to‐mesenchymal transition process, and tumor growth by mediating different targets. NIMA‐related kinase 2 (NEK2) is aberrantly expressed in lung cancer. The miR‐128/NEK2 pathway has been reported to predict prognosis in colorectal cancer; however, the determination of a relationship between miR‐128 and NEK2 in lung cancer has remained elusive. We explored the association between miR‐128 and NEK2 in lung cancer.

Methods

MiR‐128 and NEK2 expression were examined in 15 lung cancer tissues by real time‐PCR. Lung cancer SK‐MES‐1 cells were transfected with miR‐128 mimic, an inhibitor or a negative control. MiR‐128 and NEK2 expression levels were detected using quantitative real time‐PCR and Western blot. SK‐MES‐1 cell apoptosis was performed by flow cytometry.

Results

Compared to adjacent non‐tumor tissues, miR‐128 was downregulated and NEK2 was upregulated in 15 lung cancer tissues. Lung cancer SK‐MES‐1 cells transfected with miR‐128 mimic induced a higher apoptotic rate than those transfected with the negative control. Dual luciferase assay further confirmed that NEK2 was a direct target of miR‐128 in lung cancer, and transfection with miR‐128 mimic could decrease the NEK2 protein level while the miR‐128 inhibitor increased NEK2 expression. Finally, the apoptotic effect of lung cancer cells induced by miR‐128 mimic could be reversed by NEK2 overexpression.

Conclusions

NEK2 was regulated by miR‐128 in lung cancer and miR‐128 induced lung cancer cell apoptosis by mediating NEK2 expression.

Deguelin inhibits epithelial-to-mesenchymal transition and metastasis of human non-small cell lung cancer cells by regulating NIMA-related kinase 2

Background

Non‐small cell lung cancer is a lethal malignancy with a high mortality rate. Deguelin displays an anti‐tumor effect and inhibits metastasis in various cancers. The aberrant expression of NIMA‐related kinase 2 (NEK2) indicates poor prognosis and induces epithelial‐to‐mesenchymal transition (EMT) and metastasis processes. However, the underlying mechanism between deguelin and NEK2 has remained elusive.

Methods

NSCLC cell lines were treated with deguelin. Wound‐healing and invasion assays were applied to study the inhibitory effect of deguelin on NSCLC cells. EMT markers, E‐cadherin and Vimentin, were also detected by Western blot. NEK2 protein and messenger RNA expression levels were evaluated when NSCLC cells were treated with different concentrations of deguelin. The effect of NEK2 on NSCLC cell metastasis was evaluated through NEK2 knockdown. To investigate whether deguelin induced EMT by regulating NEK2, we overexpressed NEK2 in both NCI‐H520 and SK‐MES‐1 cell lines, and then used real time‐PCR to study the E‐cadherin and Vimentin messenger RNA expression in both NSCLC cells.

Results

Deguelin inhibited migration and invasion processes in NSCLC cell lines and decreased NEK2 expression in a concentration‐dependent manner. Furthermore, NEK2 knockdown inhibited NSCLC cell migration and invasion. Finally, overexpressing NEK2 in NCI‐H520 and SK‐MES‐1 cells could restore the inhibition of metastasis induced by deguelin.

Conclusions

Deguelin could inhibit EMT and metastasis, while overexpression of NEK2 promotes these processes. Deguelin could decrease NEK2 expression, while NEK2 overexpression could restore deguelin‐induced inhibition of metastasis.