Targeted disruption of Nemo-like kinase inhibits tumor cell growth by simultaneous suppression of cyclin D1 and CDK2 in human hepatocellular carcinoma

Grass carp (Ctenopharyngodon idella) NLK2 inhibits IFN I response through blocking MAVS-IRF3 axis

In mammals, nemo-like kinase 2 (NLK2) is a conservative protein kinase involved in Wnt/β-catenin signaling pathway and immune response. However, the role of NLK2 in immune response in teleost remain unclear. In this study, we identified an ortholog of mammalian NLK from grass carp (Ctenopharyngodon idellus) named CiNLK2. CiNLK2 shares a high level of homology with the counterparts, especially with that of Cyprinus carpio. CiNLK2 was ubiquitously expressed in all tested tissues (liver, brain, spleen, gill, kidney and eye) and its expression was up-regulated under the treatment with poly I:C or GCRV. Overexpression of CiNLK2 suppressed the production of IFN I in CIK cells whether or not treated with poly I:C. However, knockdown of CiNLK2 increased the expression level of IFN I. The analysis of subcellular localization showed that CiNLK2 protein was scattered throughout the cytoplasm and nucleus. In terms of mechanism, CiNLK2 can directly interact with MAVS and inhibit MAVS-induced IFN I response. Moreover, CiNLK2 increased the phosphorylation level of MAVS, which led to the degradation of MAVS protein. On the other hand, CiNLK2 suppressed the phosphorylation and nuclear translocation of IRF3. In general, CiNLK2 served as an inhibitor for IFN I response by targeting MAVS-IRF3 signal axis.

Dysregulation of miR-1-3p: An Early Event in Colitis-Associated Dysplasia

Detection of colorectal dysplasia during surveillance colonoscopy remains the best method of determining risk for colitis-associated colorectal cancer (CAC). miRNAs (miRs) show great promise as tissue-specific biomarkers of neoplasia. The goal of this study was to explore the miR expression profile of precancerous dysplastic lesions in the AOM/DSS mouse model and identify early molecular changes associated with CAC. Epithelial cells were laser-microdissected from the colonic mucosa (inflamed versus dysplastic) of mice with AOM/DSS-induced colitis. A miR signature that can distinguish inflamed non-neoplastic mucosa from dysplasia was identified. Bioinformatic analyses led to the discovery of associated miR gene targets and enriched pathways and supported the construction of a network interaction map. miR-1a-3p was one of the miRs with the highest number of predicted targets, including Cdk6. Interestingly, miR-1a-3p and Cdk6 were down- and up-regulated in dysplastic lesions, respectively. Transfection of HCT116 and RKO cells with miR-1a-3p mimics induced apoptosis and cell cycle arrest in G1, suggesting its biological function. A slight reduction in the level of CDK6 transcripts was also observed in cells transfected with miR-1. These data provide novel insight into the early molecular alterations that accompany the development of CAC and identify a miR signature that represents a promising biomarker for the early detection of colitis-associated dysplasia.

The Key Role of microRNAs in Initiation and Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the main type of primary liver malignancy and the fourth leading cause of cancer-related death worldwide. MicroRNAs (miRNAs), a type of non-coding RNA that regulates gene expression mainly on post-transcriptional level has a confirmed and important role in numerous biological process. By regulating specific target genes, miRNA can act as oncogene or tumor suppressor. Recent evidence has indicated that the deregulation of miR-NAs is closely associated with the clinical pathological features of HCC. However, the precise regulatory mechanism of each miRNA and its targets in HCC has yet to be illuminated. This study demonstrates that both oncogenic and tumor suppressive miRNAs are crucial in the formation and development of HCC. miRNAs influence biological behavior including proliferation, invasion, metastasis and apoptosis by targeting critical genes. Here, we summarize current knowledge about the expression profile and function of miRNAs in HCC and discuss the potential for miRNA-based therapy for HCC.

Nemo-like kinase (NLK) gene regulates apoptosis via the p53 signaling pathway in Litopenaeus vannamei under low-temperature stress

The Nemo-like kinase (NLK) is an important serine/threonine-protein kinase in many signaling pathways. However, its function in crustaceans, such as shrimps, is still poorly understood and needs to be further explored. In the present study, the full-length cDNA of NLK from Litopenaeus vannamei (LvNLK) was cloned. The full-length LvNLK cDNA has 2497 bp, including an open reading frame (ORF) of 1524 bp encoding a protein with 507 amino acids and a predicted molecular mass of 56.1 kDa. Phylogenetic analysis revealed that LvNLK shared high similarities with NLK from other known species. Low-temperature stress markedly upregulated the expression of LvNLK. Its overexpression in hemocytes suppressed the expression of BCL2-associated X (Bax) and tumor protein P53 (p53) in vitro. Meanwhile, the BCL2 apoptosis regulator (Bcl-2), MDM2 proto-oncogene (MDM2), and Yin Yang 1 (YY1) were upregulated. Moreover, LvNLK silencing in vivo increased the susceptibility of shrimps to low-temperature stress. The generation of ROS and the rate of hemocyte apoptosis also increased when LvNLK was silenced. Additionally, qPCR results indicated that LvNLK might participate in apoptosis via the p53 signaling pathway in vitro and in vivo. These results suggested that LvNLK is indispensable for the environmental adaptation of L. vannamei. Our current findings also demonstrated that NLK is evolutionarily conserved in crustaceans and provided insights into the environmental adaptation of invertebrates.

MiR-597-5p suppresses the progression of hepatocellular carcinoma via targeting transcriptional enhancer associate domain transcription factor 1 (TEAD1)

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with high incidence and mortality. MiR-597-5p is downregulated in tumor tissues of HCC compared with non-tumor tissues. However, its role in HCC is still unknown. This study aims to assess the function of miR-597-5p in HCC development and investigate the underlying mechanism. To perform gain- and loss-of-function studies, SK-HEP-1 cells and Huh-7 cells were transfected with miR-597-5p mimics and inhibitor, respectively. MiR-597-5p markedly reduced the cell viability and the expression of Ki-67 in HCC cells. MiR-597-5p also repressed the cell cycle progression of HCC cells and the protein levels of cyclin D1 and CDK2. Moreover, miR597-5p inhibited the migration and invasion of HCC cells and decreased MMP2 and MMP9 levels. Transcriptional enhancer associate domain transcription factor 1 (TEAD1) was identified as a target of miR-597-5p by luciferase reporter assay. TEAD1 and its downstream target genes, CTGF and CYR61, were downregulated by miR-597-5p in HCC cells. Furthermore, miR-597-5p was demonstrated to function in HCC progression by targeting TEAD1 via TEAD1 expression gain and loss. Our study demonstrates that miR-597-5p represses the proliferation, migration, and invasion of HCC cells through targeting TEAD1, which provides a therapeutic target for HCC treatment.

A kinome screen reveals that Nemo-like kinase is a key suppressor of hepatic gluconeogenesis

Antihyperglycemic therapy is an important priority for the treatment of type 2 diabetes (T2D). Excessive hepatic glucose production (HGP) is a major cause of fasting hyperglycemia. Therefore, a better understanding of its regulation would be important to develop effective antihyperglycemic therapies. Using a gluconeogenesis-targeted kinome screening approach combined with transcriptome analyses, we uncovered Nemo-like kinase (NLK) as a potent suppressor of HGP. Mechanistically, NLK phosphorylates and promotes nuclear export of CRTC2 and FOXO1, two key regulators of hepatic gluconeogenesis, resulting in the proteasome-dependent degradation of the former and the inhibition of the self-transcriptional activity and expression of the latter. Importantly, the expression of NLK is downregulated in the liver of individuals with diabetes and in diabetic rodent models and restoring NLK expression in the mouse model ameliorates hyperglycemia. Therefore, our findings uncover NLK as a critical player in the gluconeogenic regulatory network and as a potential therapeutic target for T2D.

Elevated Expression of PDZD11 Is Associated With Poor Prognosis and Immune Infiltrates in Hepatocellular Carcinoma

Epithelial cells are held together by tight and adherent junctions, which are destroyed by the activation of epithelial-to-mesenchymal transition (EMT). The PLEKHA7-PDZD11 complex has been reported to be important for epithelial cell adhesion and connecting tissues. However, there is no research regarding the expression and role of PDZD11 in liver hepatocellular carcinoma (LIHC) progression. Here, we analyzed PDZD11 mRNA expression and its clinical results in LIHC patient RNA sequencing data based on different open databases. Furthermore, we examined differences in PDZD11 expression in LIHC tissues and cell lines using western blotting and real-time qPCR. These results are the first to report that the mRNA and protein levels of PDZD11 are significantly overexpressed in LIHC. Moreover, high expression of PDZD11 was correlated with poor overall survival in patients with LIHC. Gene regulatory network analysis suggested that PDZD11 is mainly involved in copper ion homeostasis, proteasome, and oxidative phosphorylation pathways. Interestingly, we found that PDZD11 levels were positively correlated with the abundance of immune infiltrates. In particular, higher infiltration levels of CD4⁺ T cells and macrophage subsets significantly affected LIHC patient prognosis. Taken together, these results demonstrate that PDZD11 could be a potential diagnostic and prognostic biomarker in LIHC.

Exosome-transferred long non-coding RNA ASMTL-AS1 contributes to malignant phenotypes in residual hepatocellular carcinoma after insufficient radiofrequency ablation

Objectives

Long non‐coding RNAs (lncRNAs) are emerging RNA regulators in cancer progression, including in hepatocellular carcinoma (HCC). Recently, insufficient radiofrequency ablation (RFA) has been reported to lead to recurrence and metastasis of residual HCC tumours. Herein, we aimed to the role of ASMTL‐AS1 in residual HCC after insufficient RFA.

Materials and methods

In vitro insufficient RFA model was simulated in Huh7 cells and subsequently named Huh7‐H cells. In vitro and in vivo assays were conducted to investigate ASMTL‐AS1 function in HCC.

Results

LncRNA ASMTL‐AS1 low expressed in normal human liver was found to be highly expressed in HCC tissues and further increased in tumours after insufficient RFA. ASMTL‐AS1 expression was related to stage, metastasis and prognosis in HCC. Huh7‐H possessed higher ASMTL‐AS1 level and more aggressive than Huh7 cells. ASMTL‐AS1 contributed to the malignancy of HCC cells both in vitro and in vivo. Mechanistically, ASMTL‐AS1 was trans‐activated by MYC and promoted NLK expression to activate YAP signalling via sequestering miR‐342‐3p in HCC. Interestingly, ASMTL‐AS1 could be wrapped by exosomes and then convey malignancy through NLK/YAP axis between cells even in residual HCC after insufficient RFA.

Conclusions

Exosomal ASMTL‐AS1 aggravates the malignancy in residual HCC after insufficient RFA via miR‐342‐3p/NLK/YAP signalling, opening a new road for the treatment of HCC and the prevention of recurrence or metastasis of residual HCC after insufficient RFA.

Role of cyclin-dependent kinases (CDKs) in hepatocellular carcinoma: Therapeutic potential of targeting the CDK signaling pathway

Liver cancer is the fourth leading cause of cancer related mortality in the world, with hepatocellular carcinoma (HCC) representing the most common primary subtype. Two-thirds of HCC patients have advanced disease when diagnosed, and for these patients, treatment strategies remain limited. In addition, there is a high incidence of tumor recurrence after surgical resection with the current treatment regimens. The development of novel and more effective agents is required. Cyclin-dependent kinases (CDKs) constitute a family of 21 different protein kinases involved in regulating cell proliferation, apoptosis, and drug resistance, and are evaluated in preclinical and clinical trials as chemotherapeutics. To summarize and discuss the therapeutic potential of targeting CDKs in HCC, recent published articles identified from PubMed were comprehensively reviewed. The key words included hepatocellular carcinoma, cyclin-dependent kinases, and CDK inhibitors. This review focuses on the emerging evidence from studies describing the genetic and functional aspects of CDKs in HCC. We also present an overview of CDK inhibitors that have shown efficacy in laboratory studies of HCC. Although many of the studies assessing CDK-targeting therapies in HCC are at the preclinical stage, there is significant evidence that CDK inhibitors used alone or in combination with established chemotherapy drugs could have significant applications in HCC.

Phosphorylation of MAVS/VISA by Nemo-like kinase (NLK) for degradation regulates the antiviral innate immune response

MAVS is essential for antiviral immunity, but the molecular mechanisms responsible for its tight regulation remain poorly understood. Here, we show that NLK inhibits the antiviral immune response during viral infection by targeting MAVS for degradation. NLK depletion promotes virus-induced antiviral cytokine production and decreases viral replication, which is potently rescued by the reintroduction of NLK. Moreover, the depletion of NLK promotes antiviral effects and increases the survival times of mice after infection with VSV. NLK interacts with and phosphorylates MAVS at multiple sites on mitochondria or peroxisomes, thereby inducing the degradation of MAVS and subsequent inactivation of IRF3. Most importantly, a peptide derived from MAVS promotes viral-induced IFN-β production and antagonizes viral replication in vitro and in vivo. These findings provide direct insights into the molecular mechanisms by which phosphorylation of MAVS regulates its degradation and influences its activation and identify an important peptide target for propagating antiviral responses.

eRF3b-37 inhibits the TGF-β1-induced activation of hepatic stellate cells by regulating cell proliferation, G0/G1 arrest, apoptosis and migration

The therapeutic management of liver fibrosis remains an unresolved clinical problem. The activation of hepatic stellate cells (HSCs) serves a pivotal role in the formation of liver fibrosis. In our previous study, matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry (MALDI‑TOF MS) was employed to identify potential serum markers for liver cirrhosis, such as eukaryotic peptide chain releasing factor 3b polypeptide (eRF3b‑37), which was initially confirmed by our group to serve a protective role in liver tissues in a C‑C motif chemokine ligand 4‑induced liver cirrhosis mouse model. Therefore, eRF3b‑37 was hypothesized to affect the activation state of HSCs, which was determined by the expression of pro‑fibrogenic associated factors in HSCs. In the present study, peptide synthesis technology was employed to elucidate the role of eRF3b‑37 in the expression of pro‑fibrogenic factors induced by transforming growth factor‑β1 (TGF‑β1) in LX‑2 cells that were treated with either control, TGF‑β1 and TGF‑β1+eRF3b‑37. 3‑(4,5‑Dimethyl‑2‑thiazolyl)‑2,5‑diphenyltetrazolium bromide and flow cytometric assays, and fluorescent microscope examinations were performed to evaluate the effects of eRF3b‑37 on proliferation viability, G0/G1 arrest, apoptosis and cell migration. The results of the present study indicated that eRF3b‑37 inhibited the activation of HSCs. The increased mRNA and protein expression of the pro‑fibrogenic factors collagen I, connective tissue growth factor and α‑smooth muscle actin (SMA) stimulated by TGF‑β1 were reduced by eRF3b‑37 via the following mechanisms: i) Inhibiting LX‑2 cell proliferation, leading to G0/G1 cell cycle arrest and inhibition of DNA synthesis by downregulating the mRNA expressions of Cyclin D1 and cyclin dependent kinase‑4, and upregulating the levels of P21; ii) increasing cell apoptosis by upregulating the mRNA level of B‑cell lymphoma-2 (Bcl‑2)‑associated X protein (Bax) and Fas, and downregulating the expression of Bcl‑2; and iii) reducing cell migration by downregulating the mRNA and protein expression of α‑SMA. In addition, eRF3b‑37 is thought to serve a role in HSCs by inhibiting TGF‑β signaling. Therefore, eRF3b‑37 may be a novel therapeutic agent for targeting HSCs for hepatic fibrosis.

Expression of Nemo-like kinase in cervical squamous cell carcinoma: a clinicopathological study

Objective

Nemo-like kinase (NLK) has been reported to play different roles in tumors. However, the role of NLK in cervical squamous cell carcinoma (CSCC) remains unknown. In this study, we explored the clinical significance including survival of NLK protein expression in CSCCs.

Patients and methods

Immunohistochemical method was performed using tissues from 130 patients with CSCC. The associations between NLK expression and the clinicopathological factors and prognosis of CSCCs were evaluated. Statistical analyses were performed using the chi-square test, the multivariate Cox proportional hazard model, and the Kaplan–Meier method.

Results

Immunohistochemical staining analysis showed that NLK was localized predominately in the nucleus of the tumor cells, and increased NLK expression was detected in 71 (54.6%) of 130 patients. NLK overexpression significantly correlated with higher histological grade (P=0.001), vascular/lymphatic invasion (P=0.010), lymph node metastasis (P=0.012), and recurrence (P=0.022). Patients with elevated NLK expression had poorer overall survival (OS) and disease-free survival (DFS) (P=0.006 and P=0.004, respectively) compared with patients with decreased NLK expression. Multivariate Cox analysis demonstrated that NLK overexpression was an independent factor for OS and DFS (P=0.034 and P=0.025, respectively).

Conclusion

NLK may be a valuable biomarker for predicting the prognosis of CSCC patients and may serve as a potential target for cancer therapy.

A systems medicine approach for finding target proteins affecting treatment outcomes in patients with non-Hodgkin lymphoma

Autoantibody profiling with a systems medicine approach can help identify critical dysregulated signaling pathways (SPs) in cancers. In this way, immunoglobulins G (IgG) purified from the serum samples of 92 healthy controls, 10 pre-treated (PR) non-Hodgkin lymphoma (NHL) patients, and 20 NHL patients who underwent chemotherapy (PS) were screened with a phage-displayed random peptide library. Protein-protein interaction networks of the PR and PS groups were analyzed and visualized by Gephi. The results indicated AXIN2, SENP2, TOP2A, FZD6, NLK, HDAC2, HDAC1, and EHMT2, in addition to CAMK2A, PLCG1, PLCG2, GRM5, GRIN2B, GRIN2D, CACNA2D3, and SPTAN1 as hubs in 11 and 7 modules of PR and PS networks, respectively. PR- and PS-specific hubs were evaluated in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. The PR-specific hubs were involved in Wnt SP, signaling by Notch1 in cancer, telomere maintenance, and transcriptional misregulation. In contrast, glutamate receptor SP, Fc receptor-related pathways, growth factors-related SPs, and Wnt SP were statistically significant enriched pathways, based on the pathway analysis of PS hubs. The results revealed that the most PR-specific proteins were associated with events involved in tumor development, while chemotherapy in the PS group was associated with side effects of drugs and/or cancer recurrence. As the findings demonstrated, PR- and PS-specific proteins in this study can be promising therapeutic targets in future studies.

microRNA-221 Enhances MYCN via Targeting Nemo-like Kinase and Functions as an Oncogene Related to Poor Prognosis in Neuroblastoma

Purpose:MYCN is one of the most well-characterized genetic markers of neuroblastoma. However, the mechanisms as to how MYCN mediate neuroblastoma tumorigenesis are not fully clear. Increasing evidence has confirmed that the dysregulation of miRNAs is involved in MYCN-mediated neuroblastoma tumorigenesis, supporting their potential as therapeutic targets for neuroblastoma. Although miR-221 has been reported as one of the upregulated miRNAs, the interplay between miR-221 and MYCN-mediated neuroblastoma progression remains largely elusive.Experimental Design: The expression of miR-221 in the formalin-fixed, paraffin-embedded tissues from 31 confirmed patients with neuroblastoma was detected by locked nucleic acid-in situ hybridization and qRT-PCR. The correlation between miR-221 expression and clinical features in patients with neuroblastoma was assessed. The mechanisms as to how miR-221 regulate MYCN in neuroblastoma were addressed. The effect of miR-221 on cellular proliferation in neuroblastoma was determined both in vitro and in vivoResults: miR-221 was significantly upregulated in neuroblastoma tumor cells and tissues that overexpress MYCN, and high expression of miR-221 was positively associated with poor survival in patients with neuroblastoma. Nemo-like kinase (NLK) as a direct target of miR-221 in neuroblastoma was verified. In addition, overexpression of miR-221 decreased LEF1 phosphorylation but increased the expression of MYCN via targeting of NLK and further regulated cell cycle, particularly in S-phase, promoting the growth of neuroblastoma cells.Conclusions: This study provides a novel insight for miR-221 in the control of neuroblastoma cell proliferation and tumorigenesis, suggesting potentials of miR-221 as a prognosis marker and therapeutic target for patients with MYCN overexpressing neuroblastoma. Clin Cancer Res; 23(11); 2905-18. ©2016 AACR.

Lentivirus-mediated knockdown of NLK inhibits small-cell lung cancer growth and metastasis

Nemo-like kinase (NLK), an evolutionarily conserved serine/threonine kinase, has been recognized as a critical regulator of various cancers. In this study, we investigated the role of NLK in human small-cell lung cancer (SCLC), which is the most aggressive form of lung cancer. NLK expression was evaluated by quantitative real-time polymerase chain reaction in 20 paired fresh SCLC tissue samples and found to be noticeably elevated in tumor tissues. Lentivirus-mediated RNAi efficiently suppressed NLK expression in NCI-H446 cells, resulting in a significant reduction in cell viability and proliferation in vitro. Moreover, knockdown of NLK led to cell cycle arrest at the S-phase via suppression of Cyclin A, CDK2, and CDC25A, which could contribute to cell growth inhibition. Furthermore, knockdown of NLK decreased the migration of NCI-H446 cells and downregulated matrix metalloproteinase 9. Treatment with NLK short hairpin RNA significantly reduced SCLC tumor growth in vivo. In conclusion, this study suggests that NLK plays an important role in the growth and metastasis of SCLC and may serve as a potential therapeutic target for the treatment of SCLC.

Nemo-like kinase regulates the expression of vascular endothelial growth factor (VEGF) in alveolar epithelial cells

The canonical Wnt signaling can be silenced either through β-catenin-mediated ubiquitination and degradation or through phosphorylation of Tcf and Lef by nemo-like kinase (NLK). In the present study, we generated NLK deficient animals and found that these mice become cyanotic shortly before death because of lung maturation defects. NLK-/- lungs exhibited smaller and compressed alveoli and the mesenchyme remained thick and hyperplastic. This phenotype was caused by epithelial activation of vascular endothelial growth factor (VEGF) via recruitment of Lef1 to the promoter of VEGF. Elevated expression of VEGF and activation of the VEGF receptor through phosphorylation promoted an increase in the proliferation rate of epithelial and endothelial cells. In summary, our study identifies NLK as a novel signaling molecule for proper lung development through the interconnection between epithelial and endothelial cells during lung morphogenesis.

Dysregulated miRNA in progression of hepatocellular carcinoma: A systematic review

Hepatocellular carcinoma (HCC) is the fifth most frequent cancer and the third cause of cancer-related mortality worldwide. The primary risk factor for HCC is liver cirrhosis secondary to persistent infection with hepatitis B virus or hepatitis C virus. Although a number of cellular phenomena and molecular events have been reported to facilitate tumor initiation, progression and metastasis, the exact etiology of HCC has not yet been fully uncovered. miRNA, a class of non-coding RNA, negatively regulate post-transcriptional processes that participate in crucial biological processes, including development, differentiation, apoptosis and proliferation. In the liver, specific miRNA can be negative regulators of gene expression. Recent studies have uncovered the contribution of miRNA to cancer pathogenesis as they can function as oncogenes or tumor suppressor genes. In addition, other studies have demonstrated their potential value in the clinical management of patients with HCC as some miRNA may be used as prognostic or diagnostic markers. In this review, we summarize the current knowledge about the roles of miRNA in the carcinogenesis and progression of HCC.

miR-362-3p targets nemo-like kinase and functions as a tumor suppressor in renal cancer cells

MicroRNAs (miRNAs) have been demonstrated to exhibit abnormal expression patterns in various types of human cancer. The aim of the present study was to identify a novel tumor suppressor microRNA (miR) and investigate its physiological function and mechanism in renal cell carcinoma (RCC). The expression levels of miRNA (miR)‑362‑3p expres were measured in 47 pairs of RCC and adjacent normal tissue samples, using reverse transcription-quantitative polymerase chain reaction analysis. In addition, miR‑362‑3p was transfected into renal cancer cells to investigate its role in the regulation of cell proliferation, migration, invasion, apoptosis and cell cycle. Identification of the target gene of miR‑362‑3p was performed using luciferase reporter assays and western blot analyses. The results demonstrated that the expression levels of miR‑362‑3p were downregulated in the RCC tissue samples, compared with the adjacent normal tissue samples. The upregulation of miR‑362‑3p using a synthesized mimic suppressed the proliferation, migration and invasion of the renal cancer cells, and induced cell apoptosis and G1 phase arrest. Further experiments demonstrated that the overexpression of miR‑362‑3p resulted in decrease expression levels of nemo-like kinase. These results suggested that miR-362-3p functions as a tumor suppressor in RCC, and may serve as a potential molecular target in the treatment of RCC.

NLK functions to maintain proliferation and stemness of NSCLC and is a target of metformin

Objective

Nemo-like kinase (NLK) is an evolutionarily conserved serine/threonine kinase that regulates the activity of a wide range of signal transduction pathways. Metformin, an oral antidiabetic drug, is used for cancer prevention. However, the significance and underlying mechanism of NLK and metformin in oncogenesis has not been fully elucidated. Here, we investigate a novel role of NLK and metformin in human non-small cell lung cancer (NSCLC).

Materials and methods

NLK expression was analyzed in 121 NSCLCs and 92 normal lung tissue samples from benign pulmonary disease. Lentivirus vectors with NLK-shRNA were used to examine the effect of NLK on cell proliferation and tumorigenesis in vitro. Then, tumor xenograft mouse models revealed that NLK knockdown cells had a reduced ability for tumor formation compared with the control group in vivo. Multiple cell cycle regulator expression patterns induced by NLK silencing were examined by western blots in A549 cells. We also employed metformin to study its anti-cancer effects and mechanisms. Cancer stem cell property was checked by tumor sphere formation and markers including CD133, Nanog, c-Myc, and TLF4.

Results

Immunohistochemical (IHC) analysis revealed that NLK expression was up-regulated in NSCLC cases (p < 0.001) and correlated with tumor T stage (p < 0.05). Silencing of NLK suppressed cell proliferation and tumorigenicity significantly in vitro and in vivo, which might be modulated by JUN family proteins. Furthermore, metformin selectively inhibits NLK expression and proliferation in NSCLC cells, but not immortalized noncancerous lung bronchial epithelial cells. In addition, both NLK knockdown and metformin treatment reduced the tumor sphere formation capacity and percentage of CD133+ cells. Accordingly, the expression level of stem cell markers (Nanog, c-Myc, and TLF4) were decreased significantly.

Conclusion

NLK is critical for cancer cell cycle progression, and tumorigenesis in NSCLC, NLK knockdown, and metformin treatment inhibit cancer cell proliferation and stemness. Metformin inhibits NLK expression and might be a potential treatment strategy for NSCLC.

Upregulation of nemo-like kinase is an independent prognostic factor in colorectal cancer

AIM: To investigate the expression and oncogenic role of nemo-like kinase (NLK) in colorectal cancer.

METHODS: Expression of NLK protein was assessed by immunohistochemistry in tissue specimens from 56 cases of normal colorectal mucosa, 51 cases of colorectal adenoma, and 712 cases of colorectal cancer. In addition, NLK expression was knocked down using a lentivirus carrying NLK small hairpin RNA in colorectal cancer cells. Cell viability methylthiazoletetrazolium assays, colony formation assays, flow cytometry cell cycle assays, Transwell migration assays, and gene expression assays were performed to explore its role on proliferation and migration of colorectal cancer.

RESULTS: Expression of NLK protein progressively increased in tissues from the normal mucosa through adenoma to various stages of colorectal cancer. Overexpression of NLK protein was associated with advanced tumor-lymph node-metastasis stages, poor differentiation, lymph node and distant metastases, and a higher recurrence rate of colorectal cancer (P < 0.05). Multivariate analyses showed that NLK expression was an independent prognostic factor to predict overall survival (hazard ratio 2.57, 95% confidence interval: 1.66-3.98; P < 0.001) and disease-free survival (hazard ratio 1.96, 95% confidence interval: 1.40-2.74: P < 0.001) of colorectal cancer patients. Furthermore, knockdown of NLK expression in colorectal cancer cell lines reduced cell viability, colony formation, and migration, and arrested tumor cells at the G0/G1 phase of the cell cycle. At the gene level, knockdown of NLK expression inhibited matrix metalloproteinase-2 expression in colorectal cancer cells.

CONCLUSION: NLK overexpression is an independent prognostic factor in colorectal cancer and knockdown of NLK expression inhibits colorectal cancer progression and metastasis.

Lentivirus‑delivered nemo‑like kinase small interfering RNA inhibits laryngeal cancer cell proliferation in vitro

Laryngeal squamous cell carcinoma is the most common form of head and neck squamous cell carcinoma. Multiple approaches have been applied to treat this type of cancer; however, no significant improvement in survival rate has been achieved. In the present study, the role of nemo‑like kinase (NLK) in human laryngeal carcinoma Hep‑2 cells was investigated. NLK has been identified as an important regulator of cell growth, patterning and cell death in a variety of organisms. Lentivirus‑mediated‑shRNA was employed to silence endogenous NLK expression. Downregulation of the expression of NLK following lentivirus infection was confirmed using reverse transcription quantitative polymerase chain reaction and western blot analysis. The effects of NLK downregulation on Hep‑2 cell proliferation and cell cycle progression were analyzed using an MTT assay and flow cytometry, respectively. Downregulation of NLK also inhibited tumorigenesis and regulated the expression of cell cycle protein expression levels. Therefore, it was hypothesized that NLK is necessary for cell survival and tumorigenesis in laryngeal cancer cells. Furthermore, the absence of NLK may lead to cancer cell death. Collectively, the results of the present study demonstrated that the lentivirus‑mediated targeted disruption of NLK may be a promising therapeutic method for the treatment of laryngeal cancer.

Zinc finger X-chromosomal protein (ZFX) is a significant prognostic indicator and promotes cellular malignant potential in gallbladder cancer

The Zinc finger X-chromosomal protein (ZFX), a novel member of the Krueppel C2H2-type zinc finger protein family, has been implicated in multiple human cancers. However, the clinical significance of ZFX expression in gallbladder cancer (GBC) remains largely unknown. In this study, we focused on the clinical significance, biological function and mechanism of ZFX in GBC, and found that ZFX protein overexpression was frequently detected in GBC tissues. The expression of ZFX was significantly correlated with histological grade, perineural invasion, and margin status and lead to a significantly poorer prognosis in GBC patients(P <0.001). Furthermore, knockdown of ZFX result in significant inhibition of proliferation, migration, invasion and cause cell cycle arrest in GBC-SD cells, while over-expression of ZFX in NOZ shows the opposite results. Activation of PI3K/AKT pathway maybe the potential mechanism behind these effects. In conclusion, ZFX may serve as a oncogene and could be used as a potential prognostic marker and genetic treatment target for GBC patients.

Downregulation of microRNA-409-3p promotes aggressiveness and metastasis in colorectal cancer: an indication for personalized medicine

BACKGROUND

MicroRNAs play an essential role in colorectal cancer development and progression. Aberrant miR-409-3p expression has been reported in several cancers. However, the clinical significance and functions of miR-409-3p in human CRC were not entirely clear.

METHODS

miR-409-3p expression levels were determined in 45 pairs of primary CRC and their corresponding adjacent non-tumor tissues by qPCR. The effects of ectopic expression of miR-409-3p on CRC cells proliferation, wound healing, metastasis were investigated by CCK-8, transwell assay and peritoneal spreading nude mice model.

RESULTS

Statistical analysis of clinical cases revealed that low miR-409-3p expression had inclinations towards lager tumor size and local invasion. Ectopic expression of miRNA mimics suggested that miR-409-3p could inhibits the abilities of proliferation, wound healing, metastasis and invasion in CRC cells. Notably, we found the NLK could be a potential target of miR-409-3p.

CONCLUSION

Our results suggest that miR-409-3p functions as a tumor suppressor by inhibiting the development and metastasis of CRC, suggesting that miR-409-3p is expected to become a new diagnostic marker and a new target of the treatment of CRC.

Prognostic significance of Nemo-like kinase expression in patients with hepatocellular carcinoma

Nemo-like kinase (NLK) is an evolutionarily conserved serine/threonine protein kinase and belongs to the extracellular signal-regulated kinases/microtubule-associated protein kinase families (Erks/MAPKs). Previous studies have indicated that abnormal expressions of NLK played critical roles in various types of human cancers. Recent studies suggested that NLK expression was significantly upregulated in the hepatocellular carcinoma (HCC) specimens. However, the clinical significance of NLK expression in HCC remains largely unknown. In this study, we focused on the clinical significance of NLK in HCC and found that high expression of NLK was significantly associated with Edmondson-Steiner grade (P = 0.002), tumor size (P = 0.022), and no. of tumor nodules (P < 0.001), and NLK was positively correlated with proliferation marker Ki-67 (P < 0.01). Univariate analysis suggested that NLK expression was associated with poor prognosis (P < 0.001). Multivariate analysis indicated that NLK expression was an independent prognostic indicator for HCC (P = 0.0370). In conclusion, NLK overexpression is associated with poor overall survival in patients with HCC, it might be an independent poor prognostic marker for HCC.

Nemo‑like kinase expression predicts poor survival in colorectal cancer

Nemo‑like kinase (NLK), a serine/threonine protein kinase, was previously reported to be associated with tumor proliferation and invasion. The present study aimed to evaluate whether NLK participates in the tumorigenesis and progression of colorectal cancer (CRC). NLK expression was examined using reverse transcription quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis in 50 paired CRC tissues as well as immunohistochemical analysis of 406 cases of primary CRC tissues and paired non‑cancerous tissues. Correlations between NLK expression, the clinicopathological features of CRC patients and clinical outcome were then analyzed. NLK expression was found to be significantly higher in CRC tissues as well as associated with the depth of tumor invasion, lymph node metastasis, distant metastasis, histological differentiation, vascular invasion and advanced tumor stage. Patients with NLK‑positive tumors demonstrated higher rates of recurrence and mortality than patients with NLK‑negative tumors. Multivariate analyses revealed that NLK expression was an independent factor for overall survival [hazard ratio (HR)=0.035; 95% confidence interval (CI)=0.02‑0.19; P<0.001] and disease‑free survival (HR=0.033; 95% CI=0.007‑0.09; P<0.001) in CRC patients. In conclusion, the results of the present study indicated that NLK may serve as a novel biomarker for tumor recurrence and survival for CRC patients.

Role of MicroRNAs in Hepatocellular Carcinoma

CONTEXT

MicroRNAs (miRNAs) are small, noncoding RNAs that play an important role in posttranscriptional gene regulation and function as negative gene regulators. They are an abundant class of RNA, each of which can control hundreds of gene targets and regulate diverse biological processes such as hematopoiesis, organogenesis, apoptosis and cell proliferation. Aberrant miRNA expression contributes to tumorigenesis and cancer progression.

EVIDENCE ACQUISITION

In this study we provided a summarized review of the most important new data available on hepatocellular carcinoma (HCC)-associated miRNAs. The data were collected through searching the related keywords and were categorized and summarized in different sections.

RESULTS

Researchers have reported that miRNAs can repress the expression of important cancer-related genes and might be helpful in the diagnosis and treatment of cancer. During the past two decades, numerous studies have shown that miRNAs play an essential role in inhibiting HCC via several different pathways. Deregulated miRNAs may contribute to carcinogenesis, indicating that miRNAs can act as tumor suppressors and oncogenes.

CONCLUSIONS

In this mini review, we highlight current findings and discuss recent work to determine the contribution of miRNA expression to the maintenance and growth of HCC, thereby providing a significant source of hope that miRNAs could serve as therapeutic targets.

Nemo-like kinase is critical for p53 stabilization and function in response to DNA damage

The DNA damage response (DDR) acts as a protective mechanism for maintaining cell homeostasis. Nemo-like kinase (NLK) is a serine/threonine-protein kinase that has an important role in many pathways; however, its function in the DDR has not yet been defined. In our study, NLK-deficient HCT116 cells were found to be resistant to etoposide-induced cell death. We demonstrated that NLK is required for p53 activation in response to DNA damage. Remarkably, mechanistic studies revealed that NLK interacts with p53 and stabilizes p53 by blocking MDM2-mediated p53 ubiquitination and degradation. Furthermore, NLK enhances p53 activity and affects expression downstream of p53. Interestingly, these functions of NLK are not related to its kinase activity. Consistent with these results, NLK-deficient cells have a resistance effect on DNA damage. Therefore, these findings emphasize that NLK is a novel factor in DDR mechanisms.

NLK, a novel target of miR-199a-3p, functions as a tumor suppressor in colorectal cancer

We previously reported that miR-199a-3p is a newly biomarker for diagnosis and novel prognostic indicator in colorectal cancer. However, the miR-199a-3p regulatory mechanism and its target genes are still unclear. In our present study, we demonstrated miR-199a-3p could directly target 3'-UTR of NLK gene by luciferase reporter assay and western blot analysis. We detected NLK expressions in 92 colorectal cancer cases to evaluate its clinicopathologic characteristics in colorectal cancer. Our results showed that NLK expression was significantly downregulated in cancer tissues than NATs, and NLK low-expression was associated with lymph node metastasis, venous invasion, liver metastasis and the TNM stage (P<0.05). Moreover, Kaplan-Meier analysis showed that low expression of NLK correlated with a shorter overall survival rates of patients with CRC (P<0.05). In vitro, we also found that NLK suppressed the biological behaviors of colorectal cancer cells, including the abilities of cell proliferation, clone formation, wound healing, migration and invasion (P<0.05), while overexpression of NLK increased the apoptotic rate of colorectal cancer cells. All these results suggested that NLK was an identified miR-199a-3p target gene and functioned as a tumor suppressor gene in colorectal cancer. NLK could be a novel direction for developing diagnostic and therapeutic approaches in colorectal cancer.

Association of nuclear-localized Nemo-like kinase with heat-shock protein 27 inhibits apoptosis in human breast cancer cells

Nemo-like kinase (NLK), a proline-directed serine/threonine kinase regulated by phosphorylation, can be localized in the cytosol or in the nucleus. Whether the localization of NLK can affect cell survival or cell apoptosis is yet to be disclosed. In the present study we found that NLK was mainly localized in the nuclei of breast cancer cells, in contrast to a cytosolic localization in non-cancerous breast epithelial cells. The nuclear localization of NLK was mediated through direct interaction with Heat shock protein 27 (HSP27) which further protected cancer cells from apoptosis. The present study provides evidence of a novel mechanism by which HSP27 recognizes NLK in the breast cancer cells and prevents NLK-mediated cell apoptosis.

Prognostic significance of nemo-like kinase in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a highly metastatic malignancy, which is highly prevalent in Southeast Asia and North Africa. Recent studies implicated the critical role of nemo‑like kinase (NLK) in tumor biology. However, the functional role of NLK in NPC has yet to be elucidated. In the present study, the significance of NLK positivity in NPC was examined. NLK expression was evaluated by immunohistochemistry in a relatively large sample of patients with NPC (n=352) from December 1, 2002 to December 1, 2009. The correlation between the NLK expression status and clinicopathological features and prognosis was investigated. Univariate and multivariate Cox regression models were developed to evaluate the association between the NLK status and the relative risks for relapse and mortality. In total, 54% (190/352) of NPC samples were identified as positive for NLK. By contrast, all 176 specimens of adjacent normal tissue were negative for NLK. NLK positivity was associated with tumor extent, regional lymph node status and distant metastases. A Kaplan‑Meier survival analysis demonstrated that patients with NLK‑positive NPC exhibited significantly shorter disease‑free survival (DFS) and overall survival (OS). Furthermore, Cox regression analysis revealed that NLK positivity was an unfavorable prognostic indicator of DFS and OS in NPC, independent of other features. Additionally, NLK‑positive patients with NPC without distant metastases were more likely to relapse compared with NLK‑negative patients with NPC without distant metastases. The present study indicates that NLK is a good prognostic marker for NPC.

MiR-101 functions as a tumor suppressor by directly targeting nemo-like kinase in liver cancer

Nemo-like kinase (NLK), an evolutionarily conserved MAP kinase-related kinase, has been reported to be involved in the development of hepatocellular carcinoma (HCC), but the underlying mechanisms leading to oncogenic NLK are poorly understood. A comprehensive microRNA (miRNA) profiling analysis on human HCC tissues identified four downregulated miRNAs that may target NLK. Ectopic expression of miRNA mimics suggested that miR-101 could suppress NLK in HCC cells. Notably, ectopic miR-101 expression repressed cancer cell growth and proliferation and imitated NLK knockdown effect on HCC cells. In conclusion, we suggest that miR-101 functions as a tumor suppressor by regulating abnormal NLK activity in liver.

Transcript profiling identifies iqgap2(-/-) mouse as a model for advanced human hepatocellular carcinoma

It is broadly accepted that genetically engineered animal models do not always recapitulate human pathobiology. Therefore identifying best-fit mouse models of human cancers that truly reflect the corresponding human disease is of vital importance in elucidating molecular mechanisms of tumorigenesis and developing preventive and therapeutic approaches. A new hepatocellular carcinoma (HCC) mouse model lacking a novel putative tumor suppressor IQGAP2 has been generated by our laboratory. The aim of this study was to obtain the molecular signature of Iqgap2^−/− HCC tumors and establish the relevance of this model to human disease. Here we report a comprehensive transcriptome analysis of Iqgap2^−/− livers and a cross-species comparison of human and Iqgap2^−/− HCC tumors using Significance Analysis of Microarray (SAM) and unsupervised hierarchical clustering analysis. We identified the Wnt/β-catenin signaling pathway as the top canonical pathway dysregulated in Iqgap2^−/− livers. We also demonstrated that Iqgap2^−/− hepatic tumors shared genetic signatures with HCC tumors from patients with advanced disease as evidenced by a 78% mouse-to-human microarray data set concordance rate with 117 out of 151 identified ortholog genes having similar expression profiles across the two species. Collectively, these results indicate that the Iqgap2 knockout mouse model closely recapitulates human HCC at the molecular level and supports its further application for the study of this disease.

Prognostic significance of nemo-like kinase (NLK) expression in patients with gallbladder cancer

Nemo-like kinase (NLK), a serine/threonine protein kinase, has been implicated in tumor development and progression, and plays an important role in diverse signaling pathways by phosphorylating a variety of transcription factors. Recent studies demonstrated that altered expression of NLK was observed in various types of human cancers. However, the clinical significance of NLK expression in gallbladder cancer (GBC) remains largely unknown. In this study, we focused on the clinical significance of NLK in GBC, and found that nuclear NLK protein overexpression was frequently detected in GBC tissues. The overexpression of NLK was significantly correlated with histological grade, TNM stage, and perineural invasion. The results of Kaplan-Meier analysis indicated that a high expression level of NLK resulted in a significantly poorer prognosis of GBC patients (P = 0.002). Furthermore, multivariate Cox regression analysis showed that high NLK expression was an independent prognostic factor for GBC patients (HR = 3.077). In conclusion, overexpression of NLK is closely related to progression of GBC, and NLK could be used as a potential prognostic marker for GBC patients.

Lentivirus-based RNA silencing of Nemo-like kinase (NLK) inhibits the CAL 27 human adenosquamos carcinoma cells proliferation and blocks G0/G1 phase to S phase

BACKGROUND

The Nemo-like kinase (NLK) is a serine/threonine-protein kinase that involved in a number of signaling pathways regulating cell fate. Variation of NLK has been shown to be associated with the risk of cancer. However, the function of NLK in oral adenosquamous carcinoma cells line CAL-27 is unknown.

METHODS

In this study, we evaluated the function of NLK in CAL-27 cells by using lentivirus-mediated RNA silence. The targeted gene expression, cell proliferation and cell cycle are investigated by RT-PCR, western-blot, MTT method, colony forming assay and flow cytometry analysis respectively.

RESULTS

After NLK silencing, the number of colonies was significantly reduced (54 ± 5 colonies/well compared with 262 ± 18 colonies/well in non-infected or 226 ± 4 colonies/well in negative control group (sequence not related to NLK sequence with mismatched bases). Using crystal violet staining, we also found that the cell number per colony was dramatically reduced. The RNA silencing of NLK blocks the G0/G1 phase to S phase progression during the cell cycle.

CONCLUSIONS

These results suggest that NLK silencing by lentivirus-mediated RNA interference would be a potential therapeutic method to control oral squamous carcinoma growth.

Nemo-like kinase, a multifaceted cell signaling regulator

Nemo-like kinase (NLK) is an evolutionarily conserved MAP kinase-related kinase. Although NLK was originally identified as a Drosophila gene affecting cell movement during eye development, recent studies show that NLK also contributes to cell proliferation, differentiation, and morphological changes during early embryogenesis and nervous system development in vertebrates. In addition, NLK has been reported to be involved in the development of several human cancers. NLK is able to play a role in multiple processes due to its capacity to regulate a diverse array of signaling pathways, including the Wnt/β-catenin, Activin, IL-6, and Notch signaling pathways. Although the molecular mechanisms that regulate NLK activity remain unclear, our recent research has presented a new model for NLK activation. Here, we summarize the current understanding of the function and regulation of NLK and discuss the aspects of NLK regulation that remain to be resolved.

M-HIFU inhibits tumor growth, suppresses STAT3 activity and enhances tumor specific immunity in a transplant tumor model of prostate cancer

Objective

In this study, we explored the use of mechanical high intensity focused ultrasound (M-HIFU) as a neo-adjuvant therapy prior to surgical resection of the primary tumor. We also investigated the role of signal transducer and activator of transcription 3 (STAT3) in M-HIFU elicited anti-tumor immune response using a transplant tumor model of prostate cancer.

Methods

RM-9, a mouse prostate cancer cell line with constitutively activated STAT3, was inoculated subcutaneously in C57BL/6J mice. The tumor-bearing mice (with a maximum tumor diameter of 5∼6 mm) were treated by M-HIFU or sham exposure two days before surgical resection of the primary tumor. Following recovery, if no tumor recurrence was observed in 30 days, tumor rechallenge was performed. The growth of the rechallenged tumor, survival rate and anti-tumor immune response of the animal were evaluated.

Results

No tumor recurrence and distant metastasis were observed in both treatment groups employing M-HIFU + surgery and surgery alone. However, compared to surgery alone, M-HIFU combined with surgery were found to significantly inhibit the growth of rechallenged tumors, down-regulate intra-tumoral STAT3 activities, increase cytotoxic T cells in spleens and tumor draining lymph nodes (TDLNs), and improve the host survival. Furthermore, M-HIFU combined with surgery was found to significantly decrease the level of immunosuppression with concomitantly increased number and activities of dendritic cells, compared to surgery alone.

Conclusion

Our results demonstrate that M-HIFU can inhibit STAT3 activities, and when combined synergistically with surgery, may provide a novel and promising strategy for the treatment of prostate cancers.

NLK is a key regulator of proliferation and migration in gallbladder carcinoma cells

Gallbladder cancer (GBC) is one of the most lethal neoplasm and is the fifth most common malignancy of gastrointestinal tract. The prognosis of gallbladder cancer is extremely terrible partially due to metastasis. Thus, understanding the molecular pathways controlling metastasis of this lethal disease may provide new targets for targeted therapeutic approach. In this study, we investigated the function of nemo-like kinase (NLK) in GBC growth and migration. Lentivirus-mediated siRNA was employed to alleviate the expression level of NLK in GBC cell lines (GBC-SD and SGC-996). Real-time PCR and western-blot analysis demonstrated that both mRNA and protein levels of NLK in GBC-SD and SGC-996 cells were decreased after infection with NLK-siRNA-expressing lentivirus (Lv-shNLK). The proliferation and in vitro tumorigenesis (colony formation) ability as well as migration of GBC-SD and SGC-996 cells with low NLK expression decreased significantly. Our results suggested that NLK is a key regulator involved in proliferation and migration of GBC, and it could be used as a potential therapeutic target for GBC.

Effect of small interfering RNA targeting wild-type FLT3 in acute myeloid leukaemia cells in vitro and in vivo

This study investigated the effect of using small interfering RNA (siRNA) to silence the wild-type FMS-like tyrosine kinase 3 (FLT3) gene in acute myeloid leukaemia (AML) cells, in vitro and in vivo. FLT3 siRNA was introduced into the human AML cell line, THP1, and into a THP1 xenograft tumour model in BALB/c nude mice. FLT3 siRNA effectively reduced both the mRNA and the protein levels of FLT3, arrested cells in G(0)/G(1) phase, inhibited THP1 cell proliferation and increased apoptosis. Intraperitoneal injection of FLT3 siRNA suppressed tumour growth in BALB/c nude mice. FLT3 siRNA treatment also reduced cyclin D1 and Bcl-2 protein levels, and increased the nuclear level of silencing mediator for retinoic acid and thyroid hormone receptors protein both in vitro and in vivo. These data suggest that FLT3 siRNA is a strong inhibitor of FLT3 expression in vitro and in vivo, and may provide a new therapeutic target for AML.

Common variation in Nemo-like kinase is associated with risk of ovarian cancer

BACKGROUND

Overexpression of mitotic kinases has been associated with prognosis, histologic grade, and clinical stage in ovarian cancer, but the relationship between inherited variation in these genes and ovarian cancer risk has not been well defined.

METHODS

We measured associations between 397 single nucleotide polymorphisms (SNPs) from 67 mitotic kinases and invasive epithelial ovarian cancer risk in two case-control studies (n = 671 cases; n = 939 controls). Thirty-six candidate SNPs (P < 0.05) were assessed in a replication analysis consisting of three additional studies (n = 1,094 cases; n = 829 controls).

RESULTS

In initial analysis, thirty-six SNPs were suggestive of association with risk of serous ovarian cancer, all subtypes of ovarian cancer, or both (P < 0.05). Replication analyses suggested an association between rs2125846 in the Nemo-like kinase (NLK) gene and ovarian cancer (serous OR = 1.36, 95% CI: 1.11-1.67, P = 1.77 × 10(-3); all subtypes OR = 1.30, 95% CI: 1.08-1.56, P = 2.97 × 10(-3)). Furthermore, rs2125846 was associated with risk in the combined discovery and replication sets (serous OR = 1.33, 95% CI: 1.15-1.54; all subtypes OR = 1.27, 95% CI: 1.12-1.45).

CONCLUSIONS

Variation in NLK may be associated with risk of invasive epithelial ovarian cancer. Further studies are needed to confirm and understand the biologic relationship between this mitotic kinase and ovarian cancer risk.

IMPACT

An association between SNPs in NLK and ovarian cancer may provide biologic insight into the development of this disease.