PBK/TOPK mediates geranylgeranylation signaling for breast cancer cell proliferation

The molecular crosstalk of the hippo cascade in breast cancer: A potential central susceptibility

The incidence of breast cancer is perpetually growing globally, and it remains a major public health problem and the leading cause of mortality in women. Though the aberrant activities of the Hippo pathway have been reported to be associated with cancer, constructive knowledge of the pathway connecting the various elements of breast cancer remains to be elucidated. The Hippo transducers, yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ), are reported to be either tumor suppressors, oncogenes, or independent prognostic markers in breast cancer. Thus, there is further need for an explicative evaluation of the dilemma with this molecular contribution of Hippo transducers in modulating breast malignancy. In this review, we summarize the intricate crosstalk of the Hippo pathway in different aspects of breast malignancy, including stem-likeness, cellular signaling, metabolic adaptations, tumor microenvironment, and immune responses. The collective data shows that Hippo transducers play an indispensable role in mammary tumor formation, progression, and dissemination. However, the cellular functions of YAP/TAZ in tumorigenesis might be largely dependent on the mechanical and biophysical cues they interact with, as well as on the cell phenotype. This review provides a glimpse into the plausible biological contributions of the cascade to the inward progression of breast carcinoma and suggests potential therapeutic prospects.

The design of TOPK inhibitors using similarity search, molecular docking, and MD simulations

Cancer is still a major cause of death worldwide. Unfortunately, the majority of current anticancer treatments suffer many limitations, mainly emergence of resistance and lack of selectivity which necessitate the search for new therapeutics. The TOPK enzyme emerges as a promising target due to its overexpression in many cancer types while being rarely detected in normal tissues. Therefore, targeting TOPK would affect the malignant activity of cancerous cells while sparing normal ones. Further, its vital role in cell division, particularly in cytokinesis, adds to its safety to normal non-multiplying cells. In this study, a combined ligand and structure-based approach was utilized to identify potential TOPK inhibitors. Previously, we identified TOPK inhibitors using a structure-based approach following the construction of a 3D homology model of the TOPK enzyme. Herein, the most active identified inhibitor (lead) was used as a search query to conduct similarity search against PubChem and ChemBridge databases. Retrieved hits were filtered using drug-like filters, docked into the ATP binding site of the enzyme, and finally, the binding free energies of all docked poses were calculated. Based on the computational scores, eight hits were selected as potential TOPK inhibitors. The predicted ADMET descriptors of the eight selected hits were generally favorable. Further, MD simulations of the top scoring hit were conducted to investigate its binding dynamics compared to the lead compound and OTS964 which agreed with the docking results and propose the selected hits as potential TOPK inhibitors. Yet, biochemical testing is still needed to validate these results.Communicated by Ramaswamy H. Sarma.

KRASG12C mutation-induced TOPK overexpression contributes to tumour progression in non-small cell lung cancer

KRAS mutation is the most frequent type of genetic mutation in non-small cell lung cancer (NSCLC), especially in lung adenocarcinoma. However, KRAS mutation can affect many biological processes and the mechanisms underlying KRAS mutation-mediate carcinogenesis in NSCLC have not been fully understood. In this research, we found that KRASG12C mutation was associated with the upregulation of T-LAK cell-originated protein kinase (TOPK), which is a well-known serine/threonine MAPK-like protein kinase implicated in tumorigenesis. The overexpression of TOPK significantly promoted the malignant phenotype of A549 cells, and TOPK silencing impaired the malignant phenotype with KRASG12C mutation. Moreover, we demonstrated that TOPK level was regulated by MAPK/ERK signalling and the transcription factor Elk1. TOPK was also found to promote the activation of NF-κB signalling in A549 cells with KRASG12C mutation via facilitating the phosphorylation of TAK1. In the in vivo tumorigenesis model, the administration of TOPK inhibitor OTS514 enhanced the anticancer effect of 5-FU, and the combinatory use of OTS514 and KRASG12C inhibitor AMG510 showed synergistic anti-tumour effect. These results suggest that KRAS-TOPK axis contributes to the progression of NSCLC and targeting this axis could synergize with anticancer effect of the existing chemotherapeutics.

Network and functional analyses of differentially expressed genes in gastric cancer provide new biomarkers associated with disease pathogenesis

BACKGROUND

Gastric cancer is a dominant source of cancer-related death around the globe and a serious threat to human health. However, there are very few practical diagnostic approaches and biomarkers for the treatment of this complex disease.

METHODS

This study aimed to evaluate the association between differentially expressed genes (DEGs), which may function as potential biomarkers, and the diagnosis and treatment of gastric cancer (GC). We constructed a protein-protein interaction network from DEGs followed by network clustering. Members of the two most extensive modules went under the enrichment analysis. We introduced a number of hub genes and gene families playing essential roles in oncogenic pathways and the pathogenesis of gastric cancer. Enriched terms for Biological Process were obtained from the "GO" repository.

RESULTS

A total of 307 DEGs were identified between GC and their corresponding normal adjacent tissue samples in GSE63089 datasets, including 261 upregulated and 261 downregulated genes. The top five hub genes in the PPI network were CDK1, CCNB1, CCNA2, CDC20, and PBK. They are involved in focal adhesion formation, extracellular matrix remodeling, cell migration, survival signals, and cell proliferation. No significant survival result was found for these hub genes.

CONCLUSIONS

Using comprehensive analysis and bioinformatics methods, important key pathways and pivotal genes related to GC progression were identified, potentially informing further studies and new therapeutic targets for GC treatment.

Identification of Timm13 protein translocase of the mitochondrial inner membrane as a potential mediator of liver fibrosis based on bioinformatics and experimental verification

OBJECTIVE

To explore the association between translocase of the inner mitochondrial membrane 13 (Timm13) and liver fibrosis.

METHODS

Gene expression profiles of GSE167033 were collected from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) between liver disease and normal samples were analyzed using GEO2R. Gene Ontology and Enrichment function were performed, a protein-protein interaction (PPI) network was constructed via the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and the hub genes of the PPI network were calculated by MCODE plug-in in Cytoscape. We validated the transcriptional and post-transcriptional expression levels of the top correlated genes using fibrotic animal and cell models. A cell transfection experiment was conducted to silence Timm13 and detect the expression of fibrosis genes and apoptosis genes.

RESULTS

21,722 genes were analyzed and 178 DEGs were identified by GEO2R analysis. The top 200 DEGs were selected and analyzed in STRING for PPI network analysis. Timm13 was one of the hub genes via the PPI network. We found that the mRNA levels of Timm13 in fibrotic liver tissue decreased (P < 0.05), and the mRNA and protein levels of Timm13 also decreased when hepatocytes were stimulated with transforming growth factor-β1. Silencing Timm13 significantly reduced the expression of profibrogenic genes and apoptosis related genes.

CONCLUSIONS

The results showed that Timm13 is closely related to liver fibrosis and silencing Timm13 significantly reduced the expression of profibrogenic genes and apoptosis related genes, which will provide novel ideas and targets for the clinical diagnosis and treatment of liver fibrosis.

Overexpression of PBK/TOPK relates to poor prognosis of patients with breast cancer: a retrospective analysis

Background

PDZ-binding kinase/T-lymphokine-activated killer cell-derived protein kinase (PBK/TOPK) is a potential prognostic indicator for patients with breast cancer. The objective of the present study was to explore the relationship between PBK/TOPK expression and clinicopathological indicators as well as the survival of patients with breast cancer.

Methods

Immunohistochemical staining was used to detect the expression of PBK/TOPK in 202 cases of breast cancer tissues. The relationship between PBK/TOPK and clinicopathological parameters was evaluated using Spearman’s rank-order correlation. The difference in PBK/TOPK expression among different molecular types was analyzed with the chi-square test. Kaplan-Meier analysis was used to create a survival curve and the log rank test was used to analyze the overall survival (OS) and disease-free survival (DFS). Prognostic correlation was assessed using univariate and multivariate Cox regression analyses.

Results

Among 202 breast cancer samples, PBK/TOPK was expressed (“+” and “++”) in 182 samples (90.1%). In addition, the histological grade, TNM stages, lymph node metastasis, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and Ki-67 were positively associated with PBK/TOPK expression. With regard to the molecular type, the expression of PBK/TOPK is different. The expression level of PBK/TOPK was negatively correlated with both the OS and DFS of breast cancer patients. The difference in the above results is meaningful (P < 0.05).

Conclusions

PBK/TOPK is overexpressed in breast cancer, and the expression is closely related to the clinicopathological characteristics of the disease. Breast cancer patients with high expression of PBK/TOPK have a poor prognosis. Therefore, healthcare providers can optimize breast cancer management using this indicator.

Breast cancer stage prediction: a computational approach guided by transcriptome analysis

Breast cancer is the second leading cancer among women in terms of mortality rate. In recent years, its incidence frequency has been continuously rising across the globe. In this context, the new therapeutic strategies to manage the deadly disease attracts tremendous research focus. However, finding new prognostic predictors to refine the selection of therapy for the various stages of breast cancer is an unattempted issue. Aberrant expression of genes at various stages of cancer progression can be studied to identify specific genes that play a critical role in cancer staging. Moreover, while many schemes for subtype prediction in breast cancer have been explored in the literature, stage-wise classification remains a challenge. These observations motivated the proposed two-phased method: stage-specific gene signature selection and stage classification. In the first phase, meta-analysis of gene expression data is conducted to identify stage-wise biomarkers that were then used in the second phase of cancer classification. From the analysis, 118, 12 and 4 genes respectively in stage I, stage II and stage III are determined as potential biomarkers. Pathway enrichment, gene network and literature analysis validate the significance of the identified genes in breast cancer. In this study, machine learning methods were combined with principal component and posterior probability analysis. Such a scheme offers a unique opportunity to build a meaningful model for predicting breast cancer staging. Among the machine learning models compared, Support Vector Machine (SVM) is found to perform the best for the selected datasets with an accuracy of 92.21% during test data evaluation. Perhaps, biomarker identification performed here for stage-specific cancer treatment would be a meaningful step towards predictive medicine. Significantly, the determination of correct cancer stage using the proposed 134 gene signature set can possibly act as potential target for breast cancer therapeutics.

Colorectal cancer concurrent gene signature based on coherent patterns between genomic and transcriptional alterations

Background

The aim of the study was to enhance colorectal cancer prognostication by integrating single nucleotide polymorphism (SNP) and gene expression (GE) microarrays for genomic and transcriptional alteration detection; genes with concurrent gains and losses were used to develop a prognostic signature.

Methods

The discovery dataset comprised 32 Taiwanese colorectal cancer patients, of which 31 were assayed for GE and copy number variations (CNVs) with Illumina Human HT-12 BeadChip v4.0 and Omni 25 BeadChip v1.1. Concurrent gains and losses were declared if coherent manners were observed between GE and SNP arrays. Concurrent genes were also identified in The Cancer Genome Atlas Project (TCGA) as the secondary discovery dataset (n = 345).

Results

The “universal” concurrent genes, which were the combination of z-transformed correlation coefficients, contained 4022 genes. Candidate genes were evaluated within each of the 10 public domain microarray datasets, and 1655 (2000 probe sets) were prognostic in at least one study. Consensus across all datasets was used to build a risk predictive model, while distinct relapse-free/overall survival patterns between defined risk groups were observed among four out of five training datasets. The predictive accuracy of recurrence, metastasis, or death was between 61 and 86% (cross-validation area under the receiver operating characteristic (ROC) curve: 0.548-0.833) from five independent validation studies.

Conclusion

The colorectal cancer concurrent gene signature is prognostic in terms of recurrence, metastasis, or mortality among 1746 patients. Genes with coherent patterns between genomic and transcriptional contexts are more likely to provide prognostication for colorectal cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09627-9.

Acetylshikonin suppresses diffuse large B-Cell Lymphoma cell growth by targeting the T-lymphokine-activated killer cell-originated protein kinase signalling pathway

Diffuse large B-cell lymphoma (DLBCL) is one of the most common causes of cancer death worldwide, and responds poorly to the existing treatments. Thus, identifying novel therapeutic targets of DLBCL is urgently needed. In this study, we found that T-lymphokine-activated killer cell-originated protein kinase (TOPK) was highly expressed in DLBCL cells and tissues. Data from the GEPIA database also indicated that TOPK was highly expressed in DLBCL tissues. The high expression levels of proteins were identified via Western blots and immunohistochemistry (IHC). TOPK knockdown inhibited cell growth and induced apoptosis of DLBCL cells with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium (MTS) and flow cytometry. Further experiments demonstrated that acetylshikonin, a compound that targeted TOPK, could attenuate cell growth and aggravate cell apoptosis through TOPK/extracellular signal-regulated kinase (ERK)-1/2 signaling, as shown by MTS, flow cytometry and Western blots. In addition, we demonstrated that TOPK modulated the effect of acetylshikonin on cell proliferation and apoptosis in U2932 and OCI-LY8 cells using MTS, flow cytometry and Western blots. Taken together, the present study suggests that acetylshikonin suppresses the growth of DLBCL cells by attenuating TOPK signaling, and the targeted inhibition of TOPK by acetylshikonin may be a promising approach for the treatment of DLBCL.

High expression of PDZ-binding kinase is correlated with poor prognosis and immune infiltrates in hepatocellular carcinoma

Background

PDZ-binding kinase (PBK) encodes a serine/threonine protein kinase related to the dual specific mitogen-activated protein kinase kinase (MAPKK) family. There is evidence that overexpression of this gene is associated with tumorigenesis. However, the role of PBK in hepatocellular carcinoma (HCC) remains unclear. Therefore, we evaluated the prognostic role of PBK and its correlation with immune infiltrates in hepatocellular carcinoma.

Methods

The expression of PBK in pan-cancers was studied by Onconmine and TIMER. The expression of PBK in HCC patients and its relationship with clinicopathological characteristics were analyzed using The Gene Expression Profiling Interactive Analysis (GEPIA), The human protein atlas database (HPA), The Cancer Genome Atlas (TCGA), and Gene Expression Omnibus (GEO) databases. Receiver operating characteristic (ROC) curve was used to determine the diagnostic value of PBK in HCC patients. The relationship between PBK and prognosis of HCC was performed by GEPIA and Kaplan Meier plotter web tool. The correlations between the clinical characteristics and overall survival were analyzed by Univariate Cox regression and Multivariate Cox hazards regression to identify possible prognostic factors for HCC patients. LinkedOmics was applied to investigate co-expression associated with PBK and to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The network map of PBK and related genes is constructed by GeneMANIA. Finally, TIMER and TISIDB were used to analyze the correlations between PBK and tumor-infiltrating immune cells.

Results

Multiple database analysis shows that PBK was highly expressed in many types of tumors, including hepatocellular carcinoma, and was significantly related to tumor stage (P=0.0089), age (P=0.0131), and race (P=0.0024) of HCC patients. The receiver operating characteristic (ROC) curve analysis showed that PBK had high diagnostic potential to HCC in GSE76427 (AUC=0.8799), GSE121248 (AUC=0.9224), GSE62232 (AUC=0.9975), and GSE84402 (AUC=0.9541). Multivariate Cox hazards regression showed that high expression of PBK may be an independent risk factor for overall survival in HCC patients (HR = 1.566, 95% CI=1.062–2.311, P= 0.024). The Protein–protein interaction network showed that PBK significantly interacted with LRRC47, ARAF, LGALS9B, TTK, DLG1, and other essential genes. Furthermore, enrichment analysis showed that PBK and co-expressed genes participated in many biological processes, cell composition, molecular functions, and pathways in HCC. Finally, the immune infiltration analysis by TIMER and TISIDB indicated that a significant tightly correlation between PBK and macrophages, neutrophils, as well as chemokines and receptors.

Conclusions

High expression of PBK is significantly correlated with poor survival and immune infiltrates in hepatocellular carcinoma. Our study suggests that PBK can be used as a biomarker of poor prognosis and potential immune therapy target in hepatocellular carcinoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02479-w.

The role of T-LAK cell-originated protein kinase in targeted cancer therapy

Targeted therapy has gradually become the first-line clinical tumor therapy due to its high specificity and low rate of side effects. TOPK (T-LAK cell-originated protein kinase), a MAP kinase, is highly expressed in various tumor tissues, while it is rarely expressed in normal tissues, with the exceptions of testicular germ cells and some fetal tissues. It can promote cancer cell proliferation and migration and is also related to drug resistance. Therefore, TOPK is considered a good therapeutic target. Moreover, a number of studies have shown that targeting TOPK can inhibit the proliferation of cancer cells and promote their apoptosis. Here, we discussed the biological functions of TOPK in cancer and summarized its tumor-related signaling network and known TOPK inhibitors. Finally, the role of TOPK in targeted cancer therapy was concluded, and future research directions for TOPK were assessed.

The design of TOPK inhibitors using structure-based pharmacophore modeling and molecular docking based on an MD-refined homology model

The TOPK enzyme (also known as PBK) is a serine-threonine protein kinase that is rarely detected in normal tissues yet is found to be overexpressed and activated in a variety of cancers such as lung, colorectal, breast, and esophageal cancer. Its prevalence in cancerous cells is associated with their poor prognosis and responsiveness to treatment. This enzyme plays a vital role in cell division, specifically in regulating cytokinesis. Unlike drugs targeting early phases in mitosis, inhibition of cytokinesis by targeting biomolecules that are unique to multiplying cells poses no threat to the normal function of non-multiplying cells. Studies have shown that inhibition of cytokinesis is promising in suppressing the growth of proliferating cancerous cells as exemplified by the complete tumor regression seen with the suppression of TOPK. Herein, we report the identification of potent TOPK inhibitors with anticancer potential using a structure-based drug design approach. The only available crystal structure of TOPK corresponds to a double mutant (T9E and T198E) dimer with a distorted N-lobe conformation, thus 3D homology modeling was implemented to rebuild the enzyme's native conformation. The resulting refined model was used to generate 3D pharmacophore models for the virtual screening of small molecules databases. Retrieved hits were filtered, docked into the ATP binding site of the enzyme, rescored, and the binding free energies for the top consensually scoring hits were calculated. Consequently, 45 compounds were selected and their in vitro inhibitory activity against TOPK was tested revealing four potential hits with the most active compound having an IC₅₀ of 3.85 µM. This compound will be chosen as a lead compound to synthesize analogs aiming to enhance potency and drug-like properties and to enrich the SAR data.

Interplay Among Metabolism, Epigenetic Modifications, and Gene Expression in Cancer

Epigenetic modifications and metabolism are two fundamental biological processes. During tumorigenesis and cancer development both epigenetic and metabolic alterations occur and are often intertwined together. Epigenetic modifications contribute to metabolic reprogramming by modifying the transcriptional regulation of metabolic enzymes, which is crucial for glucose metabolism, lipid metabolism, and amino acid metabolism. Metabolites provide substrates for epigenetic modifications, including histone modification (methylation, acetylation, and phosphorylation), DNA and RNA methylation and non-coding RNAs. Simultaneously, some metabolites can also serve as substrates for nonhistone post-translational modifications that have an impact on the development of tumors. And metabolic enzymes also regulate epigenetic modifications independent of their metabolites. In addition, metabolites produced by gut microbiota influence host metabolism. Understanding the crosstalk among metabolism, epigenetic modifications, and gene expression in cancer may help researchers explore the mechanisms of carcinogenesis and progression to metastasis, thereby provide strategies for the prevention and therapy of cancer. In this review, we summarize the progress in the understanding of the interactions between cancer metabolism and epigenetics.

An Integrative Pan-Cancer Analysis of PBK in Human Tumors

Background: PDZ binding kinase (PBK) is a serine/threonine kinase, which belongs to the mitogen-activated protein kinase kinase (MAPKK) family. It has been shown to be a critical gene in the regulation of mitosis and tumorigenesis, but the role of PBK in various cancers remains unclear. In this study, we systematically explored the prognostic and predictive value of PBK expression in 33 cancer types.

Methods: Public databases including the cBioPortal database, GDSC database, GTEx database, CCLE database, and TCGA database were used to detect the PBK expression and its association with the prognosis, clinicopathologic stage, TMB, MSI, immune microenvironment, immune checkpoints, immune cell infiltration, enrichment pathways, and IC50 across pan-cancer. The statistical analyses and visualization were conducted using R software.

Results: PBK expression is relatively high in most cancers compared to their normal counterparts, and this gene is barely expressed in normal tissues. High expression of PBK is significantly associated with poor prognosis and clinicopathologic stages I, II, and III in different cancers. Furthermore, PBK expression is strongly associated with TMB in 23 cancer types and associated with MSI in nine cancer types. Moreover, the correlation analysis of the microenvironment and immune cells indicated that PBK is negatively correlated with the immune infiltration levels but positively correlated with the infiltration levels of M0 and M1 macrophages, T cells CD4 memory activated, and T cells follicular helper. GSEA analysis revealed that the biological function or pathways relevant to the cell cycle and mitosis were frequently enriched at the level of high expression of PBK.

Conclusion: These results revealed the oncogenic role of PBK, which is significantly upregulated in various cancers and indicated poor prognosis and immune infiltration in multiple cancers. It also suggested that PBK may serve as a biomarker in multiple tumor progress and patient survival.

Identification of cancer-related module in protein-protein interaction network based on gene prioritization

With the rapid development of deep sequencing technologies, a large amount of high-throughput data has been available for studying the carcinogenic mechanism at the molecular level. It has been widely accepted that the development and progression of cancer are regulated by modules/pathways rather than individual genes. The investigation of identifying cancer-related active modules has received an extensive attention. In this paper, we put forward an identification method ModFinder by integrating both biological networks and gene expression profiles. More concretely, a gene scoring function is devised by using the regression model with [Formula: see text]-step random walk kernel, and the genes are ranked according to both of their active scores and degrees in the PPI network. Then a greedy algorithm NSEA is introduced to find an active module with high score and strong connectivity. Experiments were performed on both simulated data and real biological one, i.e. breast cancer and cervical cancer. Compared with the previous methods SigMod, LEAN and RegMod, ModFinder shows competitive performance. It can successfully identify a well-connected module that contains a large proportion of cancer-related genes, including some well-known oncogenes or tumor suppressors enriched in cancer-related pathways.

TOPK: A new predictor of the therapeutic response to neoadjuvant chemotherapy and prognosis in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) has a high probability of relapse and poor overall survival. Neoadjuvant chemotherapy (NACT) is currently a routine treatment strategy for TNBC, but some patients do not respond well. T-LAK cell-originated protein kinase (TOPK) is highly expressed in breast cancer cells and contributes to cancer cell proliferation. The present study aimed to investigate the correlation of TOPK expression with NACT treatment response and prognosis in TNBC.

METHODS

We collected 66 pairs of TNBC samples before and after NACT with docetaxel+ epirubicin+ cyclophosphamide (TEC). The Miller-Payne (MP) system was used to assess the therapeutic response to NACT in TNBC patients.

RESULTS

Immunohistochemistry analysis showed that TNBC patients with high TOPK expression before NACT had a poor treatment response and a poor prognosis. The expression of TOPK after NACT was significantly higher than that before NACT in patients with MP grade 1-3. In contrast, patients with MP grade 4-5 had significantly lower TOPK expression after NACT than before NACT, and the expression change in Ki-67 in patients with MP grade 4-5 exhibited the same trend. Survival analysis revealed that patients with TNBC accompanied by elevated TOPK expression before NACT had a worse prognosis than those with lower TOPK expression.

CONCLUSION

TOPK may be a novel predictor for the therapeutic response to NACT and prognosis for patients with TNBC.

Geranylgeraniol prevents zoledronic acid-mediated reduction of viable mesenchymal stem cells via induction of Rho-dependent YAP activation

Long-term use of zoledronic acid (ZA) increases the risk of medication-related osteonecrosis of the jaw (MRONJ). This may be attributed to ZA-mediated reduction of viable mesenchymal stem cells (MSCs). ZA inhibits protein geranylgeranylation, thus suppressing cell viability and proliferation. Geranylgeraniol (GGOH), which is a naturally found intermediate compound in the mevalonate pathway, has positive effects against ZA. However, precise mechanisms by which GGOH may help preserve stem cell viability against ZA are not fully understood. The objective of this study was to investigate the cytoprotective mechanisms of GGOH against ZA. The results showed that while ZA dramatically decreased the number of viable MSCs, GGOH prevented this negative effect. GGOH-rescued ZA-exposed MSCs formed mineralization comparable to that produced by normal MSCs. Mechanistically, GGOH preserved the number of viable MSCs by its reversal of ZA-mediated Ki67+ MSC number reduction, cell cycle arrest and apoptosis. Moreover, GGOH prevented ZA-suppressed RhoA activity and YAP activation. The results also established the involvement of Rho-dependent YAP and YAP-mediated CDK6 in the cytoprotective ability of GGOH against ZA. In conclusion, GGOH preserves a pool of viable MSCs with osteogenic potency against ZA by rescuing the activity of Rho-dependent YAP activation, suggesting GGOH as a promising agent and YAP as a potential therapeutic target for MRONJ.

PBK/TOPK: An Effective Drug Target with Diverse Therapeutic Potential

Simple Summary

Cancer is a major public health problem worldwide, and addressing its morbidity, mortality, and prevalence is the first step towards appropriate control measures. Over the past several decades, many pharmacologists have worked to identify anti-cancer targets and drug development strategies. Within this timeframe, many natural compounds have been developed to inhibit cancer growth by targeting kinases, such as AKT, AURKA, and TOPK. Kinase assays and computer modeling are considered to be effective and powerful tools for target screening, as they can predict physical interactions between small molecules and their bio-molecular targets. In the present review, we summarize the inhibitors and compounds that target TOPK and describe its role in cancer progression. The extensive body of research that has investigated the contribution of TOPK to cancer suggests that it may be a promising target for cancer therapy.

Abstract

T-lymphokine-activated killer cell-originated protein kinase (TOPK, also known as PDZ-binding kinase or PBK) plays a crucial role in cell cycle regulation and mitotic progression. Abnormal overexpression or activation of TOPK has been observed in many cancers, including colorectal cancer, triple-negative breast cancer, and melanoma, and it is associated with increased development, dissemination, and poor clinical outcomes and prognosis in cancer. Moreover, TOPK phosphorylates p38, JNK, ERK, and AKT, which are involved in many cellular functions, and participates in the activation of multiple signaling pathways related to MAPK, PI3K/PTEN/AKT, and NOTCH1; thus, the direct or indirect interactions of TOPK make it a highly attractive yet elusive target for cancer therapy. Small molecule inhibitors targeting TOPK have shown great therapeutic potential in the treatment of cancer both in vitro and in vivo, even in combination with chemotherapy or radiotherapy. Therefore, targeting TOPK could be an important approach for cancer prevention and therapy. Thus, the purpose of the present review was to consider and analyze the role of TOPK as a drug target in cancer therapy and describe the recent findings related to its role in tumor development. Moreover, this review provides an overview of the current progress in the discovery and development of TOPK inhibitors, considering future clinical applications.

PBK/TOPK promotes chemoresistance to oxaliplatin in hepatocellular carcinoma cells by regulating PTEN

Oxaliplatin (OXA) resistance limits the efficiency of treatment for hepatocellular carcinoma (HCC). Studies have shown that the PDZ-binding kinase (PBK) plays important roles in tumors. However, the role of PBK in HCC is still a problem. In this study, we explored whether PBK is involved in the chemoresistance to OXA in HCC. Expressions of PBK in six HCC cell lines and one human hepatocytes line were determined by real-time quantitative PCR and western blot analysis. SNU-182 and HepG2 cells were chosen to induce OXA resistance. PBK was silenced or overexpressed in OXA-resistant and sensitive cell lines. Then, cell proliferation, migration, and invasion were measured by cholecystokinin-8 assay and Transwell assay, respectively. The Cancer Genome Atlas dataset showed that PBK is highly expressed in HCC and signifies poor prognosis to patient with HCC. Results showed that expression of PBK in HCC cells was significantly higher than that in THLE2 cells, and it was further increased in OXA-resistant HCC cells. Silencing of PBK promoted the sensitivity of drug-resistant HCC cells to OXA. Overexpression of PBK relieved the apoptosis induced by OXA and promoted the migration and invasion of OXA-sensitive HCC cells. Thus, this study revealed that high PBK expression is correlated with OXA resistance in HCC cells, which may provide a promising therapeutic target for treating HCC.

PBK/TOPK: A Therapeutic Target Worthy of Attention

Accumulating evidence supports the role of PDZ-binding kinase (PBK)/T-lymphokine-activated killer-cell-originated protein kinase (TOPK) in mitosis and cell-cycle progression of mitotically active cells, especially proliferative malignant cells. PBK/TOPK was confirmed to be associated with the development, progression, and metastasis of malignancies. Therefore, it is a potential therapeutic target in cancer therapy. Many studies have been conducted to explore the clinical applicability of potent PBK/TOPK inhibitors. However, PBK/TOPK has also been shown to be overexpressed in normal proliferative cells, including sperm and neural precursor cells in the subventricular zone of the adult brain, as well as under pathological conditions, such as ischemic tissues, including the heart, brain, and kidney, and plays important roles in their physiological functions, including proliferation and self-renewal. Thus, more research is warranted to further our understanding of PBK/TOPK inhibitors before we can consider their applicability in clinical practice. In this study, we first review the findings, general features, and signaling mechanisms involved in the regulation of mitosis and cell cycle. We then review the functions of PBK/TOPK in pathological conditions, including tumors and ischemic conditions in the heart, brain, and kidney. Finally, we summarize the advances in potent and selective inhibitors and describe the potential use of PBK/TOPK inhibitors in clinical settings.

Constitutive Activity of Serotonin Receptor 6 Regulates Human Cerebral Organoids Formation and Depression-like Behaviors

Serotonin receptor 6 (5-HT₆R), a typical G protein-coupled receptor (GPCR) mainly expressed in the neurogenic area with constitutive activity, is of particular interest as a promising target for emotional impairment. Here, we found that 5-HT₆R was highly expressed in human NSCs and activation of the receptor promoted self-renewal of human NSCs, and thus induced the expansion and folding of human cerebral organoids; dysfunction of receptor or inhibition of its constitutive activity resulted in the premature differentiation of NSCs, which ultimately depleted the NSC pool. The following mechanistic study revealed that EPAC-CREB signaling was involved in 5-HT₆R regulation. Furthermore, we showed that mice with genetic deletion of 5-HT₆R or knockin A268R mutant presented depression-like behaviors and impaired hippocampal neurogenesis for progressive decrease of the NSC pool. Thus, this study indicates that the modulation of 5-HT₆R and its constitutive activity may provide a therapeutic alternative to alleviate depression.

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5-HT₆R regulates human neural stem cell proliferation

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The constitutive activity of 5-HT₆R is essential for human neural stem cell's multipotency

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5-HT₆R modulates neurogenesis of human cerebral organoids

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Mice with reduced constitutive activity of 5-HT₆R show depression-like behaviors

The Global Phosphorylation Landscape of SARS-CoV-2 Infection

The causative agent of the coronavirus disease 2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected millions and killed hundreds of thousands of people worldwide, highlighting an urgent need to develop antiviral therapies. Here we present a quantitative mass spectrometry-based phosphoproteomics survey of SARS-CoV-2 infection in Vero E6 cells, revealing dramatic rewiring of phosphorylation on host and viral proteins. SARS-CoV-2 infection promoted casein kinase II (CK2) and p38 MAPK activation, production of diverse cytokines, and shutdown of mitotic kinases, resulting in cell cycle arrest. Infection also stimulated a marked induction of CK2-containing filopodial protrusions possessing budding viral particles. Eighty-seven drugs and compounds were identified by mapping global phosphorylation profiles to dysregulated kinases and pathways. We found pharmacologic inhibition of the p38, CK2, CDK, AXL, and PIKFYVE kinases to possess antiviral efficacy, representing potential COVID-19 therapies.

TOPK promotes metastasis of esophageal squamous cell carcinoma by activating the Src/GSK3β/STAT3 signaling pathway via γ-catenin

Background

Esophageal squamous cell carcinoma (ESCC) is a fatal disease with poor prognosis. The predominant reason for ESCC-related death is distal metastasis. A comprehensive understanding of the molecular mechanism underlying metastasis is needed for improving patient prognosis. T-LAK cell-originated protein kinase (TOPK) is a MAPKK-like kinase, which plays a vital role in various physiological and pathophysiological processes. However, the role of TOPK in ESCC metastasis is unclear.

Methods

Tissue array was used to evaluate the correlation between TOPK expression and ESCC lymph node metastasis. Wound healing assay, transwell assay, and lung metastasis mice model were used to examine the role of TOPK in the migration of ESCC cells in vitro and in vivo. Protein kinase array, mass spectrometry (MS), and molecular modeling were used to examine the pathways and direct target proteins of TOPK that are involved in ESCC metastasis. Additionally, immunofluorescence and western blotting analyses were performed to verify these findings.

Results

The enhanced expression of TOPK was correlated with lymph node metastasis in the ESCC tissues. TOPK knockdown or treatment with the TOPK inhibitor (HI-TOPK-032) decreased the invasion and migration of ESCC cells in vitro. HI-TOPK-032 also inhibited the lung metastasis in ESCC cell xenograft in vivo model. Moreover, TOPK promoted the invasion of ESCC cells by activating the Src/GSK3β/STAT3 and ERK signaling pathways via γ-catenin.

Conclusion

The findings of this study reveal that TOPK is involved in ESCC metastasis and promoted the ESCC cell mobility by activating the Src/GSK3β/STAT3 and ERK signaling pathways. This indicated that TOPK may be a potential molecular therapeutic target for ESCC metastasis.

PDZ-Binding Kinase-Dependent Transcriptional Regulation of CCNB2 Promotes Tumorigenesis and Radio-Resistance in Glioblastoma

Increasing evidence has indicated that PDZ binding kinase (PBK) promotes proliferation, invasion, and therapeutic resistance in a variety of cancer types. However, the physiological function and therapy-resistant role of PBK in GBM remain underexplored. In this study, PBK was identified as one of the most therapy-resistant genes with significantly elevated expression level in GBM. Moreover, the high expression level of PBK was essential for GBM tumorigenesis and radio-resistance both in vitro and in vivo. Clinically, aberrant activation of PBK was correlated with poor clinical prognosis. In addition, inhibition of PBK dramatically enhanced the efficacy of radiation therapy in GBM cells. Mechanically, PBK-dependent transcriptional regulation of CCNB2 was critical for tumorigenesis and radio-resistance in GBM cells. Collectively, PBK promotes tumorigenesis and radio-resistance in GBM and may serve as a novel therapeutic target for GBM treatment.

Targeting PDZ-binding kinase is anti-tumorigenic in novel preclinical models of ACC

Adrenocortical carcinoma (ACC) is an aggressive orphan malignancy with less than 35% 5-year survival and 75% recurrence. Surgery remains the primary therapy and mitotane, an adrenolytic, is the only FDA-approved drug with wide-range toxicities and poor tolerability. There are no targeted agents available to date. For the last three decades, H295R cell line and its xenograft were the only available preclinical models. We recently developed two new ACC patient-derived xenograft mouse models and corresponding cell lines (CU-ACC1 and CU-ACC2) to advance research in the field. Here, we have utilized these novel models along with H295R cells to establish the mitotic PDZ-binding kinase (PBK) as a promising therapeutic target. PBK is overexpressed in ACC samples and correlates with poor survival. We show that PBK is regulated by FOXM1 and targeting PBK via shRNA decreased cell proliferation, clonogenicity and anchorage-independent growth in ACC cell lines. PBK silencing inhibited pAkt, pp38MAPK and pHistone H3 altering the cell cycle. Therapeutically, targeting PBK with the small-molecule inhibitor HITOPK032 phenocopied PBK-specific modulation of pAkt and pHistone H3, but also induced apoptosis via activation of JNK. Consistent with in vitro findings, treatment of CU-ACC1 PDXs with HITOPK032 significantly reduced tumor growth by 5-fold (P < 0.01). Treated tumor tissues demonstrated increased rates of apoptosis and JNK activation, with decreased pAkt and Histone H3 phosphorylation, consistent with effects observed in ACC cell lines. Together these studies elucidate the mechanism of PBK in ACC tumorigenesis and establish the potential therapeutic potential of HITOPK032 in ACC patients.

Off-target toxicity is a common mechanism of action of cancer drugs undergoing clinical trials

Ninety-seven percent of drug-indication pairs that are tested in clinical trials in oncology never advance to receive U.S. Food and Drug Administration approval. While lack of efficacy and dose-limiting toxicities are the most common causes of trial failure, the reason(s) why so many new drugs encounter these problems is not well understood. Using CRISPR-Cas9 mutagenesis, we investigated a set of cancer drugs and drug targets in various stages of clinical testing. We show that-contrary to previous reports obtained predominantly with RNA interference and small-molecule inhibitors-the proteins ostensibly targeted by these drugs are nonessential for cancer cell proliferation. Moreover, the efficacy of each drug that we tested was unaffected by the loss of its putative target, indicating that these compounds kill cells via off-target effects. By applying a genetic target-deconvolution strategy, we found that the mischaracterized anticancer agent OTS964 is actually a potent inhibitor of the cyclin-dependent kinase CDK11 and that multiple cancer types are addicted to CDK11 expression. We suggest that stringent genetic validation of the mechanism of action of cancer drugs in the preclinical setting may decrease the number of therapies tested in human patients that fail to provide any clinical benefit.

Design, Synthesis and Biological Evaluation of a New Series of 1-Aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea Derivatives as Antiproliferative Agents

To discover new antiproliferative agents with high efficacy and selectivity, a new series of 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea derivatives (7a–7t) were designed, synthesized and evaluated for their antiproliferative activity against A549, HCT-116 and PC-3 cancer cell lines in vitro. Most of the target compounds demonstrated significant antiproliferative effects on all the selective cancer cell lines. Among them, the target compound, 1-[4-chloro-3-(trifluoromethyl)phenyl]-3-{4-{{[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methyl}thio}phenyl}urea (7i) was identified to be the most active one against three cell lines, which was more potent than the positive control with an IC₅₀ value of 1.53 ± 0.46, 1.11 ± 0.34 and 1.98 ± 1.27 μM, respectively. Further cellular mechanism studies confirmed that compound 7i could induce the apoptosis of A549 cells in a concentration-dependent manner and elucidated compound 7i arrests cell cycle at G1 phase by flow cytometry analysis. Herein, the studies suggested that the 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea skeleton might be regarded as new chemotypes for designing effective antiproliferative agents.

PBK overexpression promotes metastasis of hepatocellular carcinoma via activating ETV4-uPAR signaling pathway

Invasion and metastasis are the predominant causes of lethal outcomes in patients with hepatocellular carcinoma (HCC). However, the molecular mechanism underlying the invasive or metastatic process are still insufficiently understood. Here, we first integrated several public databases and identified a novel protein kinase, PDZ-binding kinase (PBK) that was frequently upregulated and correlated with poor prognosis in patients with HCC. Gain- or loss-of-function analysis revealed that PBK promoted migration and invasion of HCC cells both in vitro and in vivo. Mechanistically, PBK enhanced uPAR expression by activating its promoter activity. Chromatin immunoprecipitation (ChIP) assay showed that ETV4 directly bound to the core region of uPAR promoter while PBK could enhance the binding of ETV4 to uPAR promoter. In orthotopic mouse model, PBK knockdown markedly inhibited the lung metastasis of HCC cells, while this effect was significantly restored by uPAR overexpression. Finally, there was a positive correlation between PBK and uPAR, ETV4 and uPAR in HCC clinical samples. Collectively, these findings revealed that PBK acted as a crucial kinase by promoting invasion and migration via the ETV4-uPAR signaling pathway, and it therefore could be a promising diagnostic biomarker and therapeutic target for HCC metastasis.

Prognostic Value of PDZ-Binding Kinase/T-LAK Cell-Originated Protein Kinase (PBK/TOPK) in Patients with Cancer

Background: PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK) plays a critical role in tumorigenesis and cancer progression. However, the prognostic roles in cancer patients are inconsistent or even controversial. Therefore, we performed a meta-analysis to investigate the prognostic value of PBK/TOPK in cancers.

Methods: Literature search was performed using several online databases (PubMed, Web of Science, Embase, Cochrane Library, and Google Scholar, National Knowledge Infrastructure and Wanfang) for eligible articles published up to May 1, 2018. The relationship between PBK/TOPK expression and prognosis in cancers was investigated by using pooled hazard ratios (HRs) with 95% confidence intervals (CIs) through STATA 12.0 software.

Results: Totally 20 eligible studies were included in this meta-analysis. The pooled results showed that carriers with high protein expression of PBK/TOPK were significantly associated with poor OS (HR: 1.69, 95% CI: 1.33-2.04) in various cancers, and patients with increased PBK/TOPK protein expression were significantly correlated with inferior RFS (HR: 1.63, 95% CI: 1.02-2.24) and short DFS (HR: 1.69, 95% CI: 1.16-2.23).

Conclusions: The findings suggest that PBK/TOPK protein expression might serve as a prognostic tumor marker in cancers.

Transcriptome profiling reveals PDZ binding kinase as a novel biomarker in peritumoral brain zone of glioblastoma

PURPOSE

Peritumoural brain zone (PT) of glioblastoma (GBM) is the area where tumour recurrence is often observed. We aimed to identify differentially regulated genes between tumour core (TC) and PT to understand the underlying molecular characteristics of infiltrating tumour cells in PT.

METHODS

17 each histologically characterised TC and PT tissues of GBM along with eight control tissues were subjected to cDNA Microarray. PT tissues contained 25-30% infiltrating tumour cells. Data was analysed using R Bioconductor software. Shortlisted genes were validated using qRT-PCR. Expression of one selected candidate gene, PDZ Binding Kinase (PBK) was correlated with patient survival, tumour recurrence and functionally characterized in vitro using gene knock-down approach.

RESULTS

Unsupervised hierarchical clustering showed that TC and PT have distinct gene expression profiles compared to controls. Further, comparing TC with PT, we observed a significant overlap in gene expression profile in both, despite PT having fewer infiltrating tumour cells. qRT-PCR for 13 selected genes validated the microarray data. Expression of PBK was higher in PT as compared to TC and recurrent when compared to newly diagnosed GBM tumours. PBK knock-down showed a significant reduction in cell proliferation, migration and invasion with increase in sensitivity to radiation and Temozolomide treatment.

CONCLUSIONS

We show that several genes of TC are expressed even in PT contributing to the vulnerability of PT for tumour recurrence. PBK is identified as a novel gene up-regulated in PT of GBM with a strong role in conferring aggressiveness, including radio-chemoresistance, thus contributing to recurrence in GBM tumours.

Targeting the T-Lak cell originated protein kinase by OTS964 shrinks the size of power-law coded heterogeneous glioma stem cell populations

Glioblastoma resists chemoradiotherapy, then, recurs to be a fatal space-occupying lesion. The recurrence is caused by re-growing cell populations such as glioma stem cells (GSCs), suggesting that GSC populations should be targeted. This study addressed whether a novel anti-cancer drug, OTS964, an inhibitor for T-LAK cell originated protein kinase (TOPK), is effective in reducing the size of the heterogeneous GSC populations, a power-law coded heterogeneous GSC populations consisting of glioma sphere (GS) clones, by detailing quantitative growth properties. We found that OTS964 killed GS clones while suppressing the growth of surviving GS clones, thus identifying clone-eliminating and growth-disturbing efficacies of OTS964. The efficacies led to a significant size reduction in GS populations in a dose-dependent manner. The surviving GS clones reconstructed GS populations in the following generations; the recovery of GS populations fits a recurrence after the chemotherapy. The recovering GS clones resisted the clone-eliminating effect of OTS964 in sequential exposure during the growth recovery. However, surprisingly, the resistant properties of the recovered-GS clones had been plastically canceled during self-renewal, and then the GS clones had become re-sensitive to OTS964. Thus, OTS964 targets GSCs to eliminate them or suppress their growth, resulting in shrinkage of the power-law coded GSC populations. We propose a therapy focusing on long-term control in recurrence of glioblastoma via reducing the size of the GSC populations by OTS964.

TOPK modulates tumour-specific radiosensitivity and correlates with recurrence after prostate radiotherapy

BACKGROUND

Tumour-specific radiosensitising treatments may enhance the efficacy of radiotherapy without exacerbating side effects. In this study we determined the radiation response following depletion or inhibition of TOPK, a mitogen-activated protein kinase kinase family Ser/Thr protein kinase that is upregulated in many cancers.

METHODS

Radiation response was studied in a wide range of cancer cell lines and normal cells using colony formation assays. The effect on cell cycle progression was assessed and the relationship between TOPK expression and therapeutic efficacy was studied in a cohort of 128 prostate cancer patients treated with radical radiotherapy.

RESULTS

TOPK knockdown did not alter radiation response in normal tissues, but significantly enhanced radiosensitivity in cancer cells. This result was recapitulated in TOPK knockout cells and with the TOPK inhibitor, OTS964. TOPK depletion altered the G1/S transition and G2/M arrest in response to radiation. Furthermore, TOPK depletion increased chromosomal aberrations, multinucleation and apoptotic cell death after irradiation. These results suggest a possible role for TOPK in the radiation-induced DNA damage checkpoints. These findings have clinical relevance, as elevated TOPK protein expression was associated with poorer clinical outcomes in prostate cancer patients treated with radical radiotherapy.

CONCLUSIONS

This study demonstrates that TOPK disruption may cause tumour-specific radiosensitisation in multiple different tumour types.

CDK1-mediated mitotic phosphorylation of PBK is involved in cytokinesis and inhibits its oncogenic activity

PDZ-binding kinase (PBK) plays a major role in proliferation and in safeguarding mitotic fidelity in cancer cells. Frequently upregulated in many cancers, PBK drives tumorigenesis and metastasis. PBK has been shown to be phosphorylated in mitosis by cyclin-dependent kinase 1 (CDK1)/cyclin B, however, no studies have been done examining PBK mitotic phosphorylation in oncogenesis. Additionally to the previously identified Threonine-9 phosphorylation, we found that Threonine-24, Serine-32, and Serine-59 of PBK are also phosphorylated. PBK is phosphorylated in vitro and in cells by CDK1 during antimitotic drug-induced mitotic arrest and in normal mitosis. We demonstrated that mitotic phosphorylation of Threonine-9 is involved in cytokinesis. The non-phosphorylatable mutant PBK-T9A augments tumorigenesis to a greater extent than wild type PBK in breast cancer cells, suggesting that PBK mitotic phosphorylation inhibits its tumor promoting activity. The PBK-T9A mutant also transforms and increases the proliferation of immortalized breast epithelial cells. Collectively, this study reveals that CDK1-mediated mitotic phosphorylation of PBK is involved in cytokinesis and inhibits its oncogenic activity.

miR-216b promotes cell growth and enhances chemosensitivity of colorectal cancer by suppressing PDZ-binding kinase

PDZ-binding kinase (PBK/TOPK) acts as oncogene in various cancers and correlates with drug response. However, few studies have examined the expression and roles of PBK in colonrectal cancer (CRC). In this study, we found a significant increase in the expression of PBK in CRC tissues and cell lines. While overexpression of PBK promoted cell growth and decreased the toxicity effect of oxaliplation (OXA), targeting PBK with short hairpin RNA (shRNA) or novel PBK inhibitor HI-TOPK-032 effectively suppressed tumor growth and potentiated chemosensitivity in vitro and in vivo. Furthermore, there was a significant inverse correlation between the expressions of miR-216b and PBK. Further found that miR-216b could down-regulate PBK levels by binding to the 3' untranslated region (3'UTR) of PBK. Notably, while miR-216b decreased cell proliferation and enhanced sensitivity of CRC cells to oxaliplation, re-expression of PBK dramatically reversed these events. Collectively, our data indicated that miR-216b may function as a tumor suppressor though regulating PBK expression, which provided promising targets and possible therapeutic strategies for CRC treatment.

TOPK promotes lung cancer resistance to EGFR tyrosine kinase inhibitors by phosphorylating and activating c-Jun

Tyrosine kinase inhibitors (TKIs) targeting the epidermal growth factor receptor (EGFR) have shown promising clinical efficacy in non-squamous non-small cell lung cancer (NSCLC); however, resistance is frequently observed in malignant cells, operating through a mechanism that remains largely unknown. The present study shows that T-lymphokine-activated killer cell-originated protein kinase (TOPK) is upregulated in NSCLC and excessively activated in TKI-refractory cells. TOPK dictates the responsiveness of lung cancers to the EGFR-targeted TKI gefitinib through the transcription factor AP-1 component c-Jun. TOPK binds directly to and phosphorylates c-Jun, which consequently activates the transcription of AP-1 target genes, including CCND1 and CDC2. TOPK silencing sensitizes EGFR-TKI-resistant lung cancer cells to gefitinib and increases gefitinib efficacy in preclinical lung adenocarcinoma xenograft models. These findings represent a novel mechanism of lung cancer resistance to TKIs and suggest that TOPK may have value both as a predictive biomarker and as a therapeutic target: TOPK-targeted therapy may synergize with EGFR-targeted therapy in lung cancers.

The crystal structure of an inactive dimer of PDZ-binding kinase

The overexpression of PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK) has been associated with hematologic tumors, breast cancer and various other cancers. However, the three-dimensional structure of PBK has not been solved. In this study, we determined the crystal structure of human PBK, which has two phospho-mimicking mutations T9E and T198E. The structural data indicated that PBK may assemble into an inactive dimer in alkaline conditions. Analytical size-exclusion chromatography and analytical ultracentrifugation confirmed that PBK exists in a conformational transition between dimers and monomers at different pH conditions. Co-IP and kinase assays suggested that the active state of PBK is a monomer and does not form a dimer even under alkaline conditions. These results showed that the conformational transition of PBK is important for its kinase activity regulation. Collectively, our observations may provide a novel starting point for structure-based functional studies.

Identification of Predictive Gene Markers for Multipotent Stromal Cell Proliferation

Multipotent stromal cells (MSCs) are known for their distinctive ability to differentiate into different cell lineages, such as adipocytes, chondrocytes, and osteocytes. They can be isolated from numerous tissue sources, including bone marrow, adipose tissue, skeletal muscle, and others. Because of their differentiation potential and secretion of growth factors, MSCs are believed to have an inherent quality of regeneration and immune suppression. Cellular expansion is necessary to obtain sufficient numbers for use; however, MSCs exhibit a reduced capacity for proliferation and differentiation after several rounds of passaging. In this study, gene markers of MSC proliferation were identified and evaluated for their ability to predict proliferative quality. Microarray data of human bone marrow-derived MSCs were correlated with two proliferation assays. A collection of 24 genes were observed to significantly correlate with both proliferation assays (|r| >0.70) for eight MSC lines at multiple passages. These 24 identified genes were then confirmed using an additional set of MSCs from eight new donors using reverse transcription quantitative polymerase chain reaction (RT-qPCR). The proliferative potential of the second set of MSCs was measured for each donor/passage for confluency fraction, fraction of EdU+ cells, and population doubling time. The second set of MSCs exhibited a greater proliferative potential at passage 4 in comparison to passage 8, which was distinguishable by 15 genes; however, only seven of the genes (BIRC5, CCNA2, CDC20, CDK1, PBK, PLK1, and SPC25) demonstrated significant correlation with MSC proliferation regardless of passage. Our analyses revealed that correlation between gene expression and proliferation was consistently reduced with the inclusion of non-MSC cell lines; therefore, this set of seven genes may be more strongly associated with MSC proliferative quality. Our results pave the way to determine the quality of an MSC population for a particular cellular therapy in lieu of an extended in vitro or in vivo assay.

Inhibitory effect of isoamericanol A from Jatropha curcas seeds on the growth of MCF-7 human breast cancer cell line by G2/M cell cycle arrest

Although various parts of J. curcas (Jatropha curcas L., Euphorbiaceae) have long been used as traditional folk medicines for their antiviral, analgesic, and/or antidotal efficacies, we are the first to investigate the role of anti-carcinogenicity of isoamericanol A (IAA) from the seed extract. Our results showed that IAA is capable of inhibiting cell proliferation in a dose-dependent manner on the human cancer cell lines of MCF-7, MDA-MB231, HuH-7, and HeLa. Flow cytometry analysis showed IAA significantly induces cell cycle arrest at G2/M on MCF-7 cells. At both protein and mRNA levels examined by western blot and real-time PCR, the results revealed increased expression of BTG2 (B-cell translocation gene 2), p21 (p21^WAF1/CIPI), and GADD45A (growth arrest and DNA-damage-inducible, alpha) after IAA treatment, but inversed expression in CDK1 (cyclin-dependent kinase 1) and cyclins B1 and B2. All these effects contribute to G2/M cell cycle arrest. Furthermore, these results coincide with the changes in molecular expressions determined by DNA-microarray analysis. Our findings indicate that IAA has an inhibitory effect on cell proliferation of MCF-7 through cell cycle arrest, giving it great potential as a future therapeutic reagent for cancers.

Downregulation of ubiquitin-specific protease 14 (USP14) inhibits breast cancer cell proliferation and metastasis, but promotes apoptosis

Breast cancer is the second leading cause of cancer-related death in women. Previously, evidence suggested that ubiquitin-specific protease 14 (USP14) was associated with various signal transduction pathways and tumourigenesis. In this study, we demonstrate that USP14 is a novel therapeutic target in breast cancer. A Western blot analysis of USP14 was performed using seven breast cancer tissues and paired adjacent normal tissues and showed that the expression of USP14 was increased in the breast cancer tissues. Immunohistochemistry was conducted on formalin-fixed paraffin-embedded sections of breast cancer samples from 100 cases. Using Pearson's χ(2) test, it was demonstrated that USP14 expression was associated with the histological grade, lymph node status and Ki-67 expression in the tumour. The Kaplan-Meier analysis revealed that increased USP14 expression in patients with breast cancer was associated with a poorer prognosis. In in vitro experiments, the highly migratory MDA-MB-231 cells that were treated with USP14-shRNA (shUSP14) exhibited decreased motility using Transwell migration assays. Next, we employed a starvation and re-feeding assay, and the CCK-8 assay demonstrated that USP14 regulated breast cancer cell proliferation. Furthermore, we used flow cytometry to analyse cellular apoptosis following USP14 knockdown. Taken together, our results suggested that USP14 was involved in the progression of breast cancer.

YAP and TAZ Take Center Stage in Cancer

The Hippo pathway was originally identified and named through screening for mutations in Drosophila, and the core components of the Hippo pathway are highly conserved in mammals. In the Hippo pathway, MST1/2 and LATS1/2 regulate downstream transcription coactivators YAP and TAZ, which mainly interact with TEAD family transcription factors to promote tissue proliferation, self-renewal of normal and cancer stem cells, migration, and carcinogenesis. The Hippo pathway was initially thought to be quite straightforward; however, recent studies have revealed that YAP/TAZ is an integral part and a nexus of a network composed of multiple signaling pathways. Therefore, in this review, we will summarize the latest findings on events upstream and downstream of YAP/TAZ and the ways of regulation of YAP/TAZ. In addition, we also focus on the crosstalk between the Hippo pathway and other tumor-related pathways and discuss their potential as therapeutic targets.