TOPK (T-LAK cell-originated protein kinase) inhibitor exhibits growth suppressive effect on small cell lung cancer

Comprehensive Analysis of the Mechanism of Anoikis in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC), ranking as the second-leading cause of global mortality among malignancies, poses a substantial burden on public health worldwide. Anoikis, a type of programmed cell death, serves as a barrier against the dissemination of cancer cells to distant organs, thereby constraining the progression of cancer. Nevertheless, the mechanism of genes related to anoikis in HCC is yet to be elucidated.

Methods

This paper's data (TCGA-HCC) were retrieved from the database of the Cancer Genome Atlas (TCGA). Differential gene expression with prognostic implications for anoikis was identified by performing both the univariate Cox and differential expression analyses. Through unsupervised cluster analysis, we clustered the samples according to these DEGs. By employing the least absolute shrinkage and selection operator Cox regression analysis (CRA), a clinical predictive gene signature was generated from the DEGs. The Cell-Type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm was used to determine the proportions of immune cell types. The external validation data (GSE76427) were procured from Gene Expression Omnibus (GEO) to verify the performance of the clinical prognosis gene signature. Western blotting and immunohistochemistry (IHC) analysis confirmed the expression of risk genes.

Results

In total, 23 prognostic DEGs were identified. Based on these 23 DEGs, the samples were categorized into four distinct subgroups (clusters 1, 2, 3, and 4). In addition, a clinical predictive gene signature was constructed utilizing ETV4, PBK, and SLC2A1. The gene signature efficiently distinguished individuals into two risk groups, specifically low and high, demonstrating markedly higher survival rates in the former group. Significant correlations were observed between the expression of these risk genes and a variety of immune cells. Moreover, the outcomes from the validation cohort analysis aligned consistently with those obtained from the training cohort analysis. The results of Western blotting and IHC showed that ETV4, PBK, and SLC2A1 were upregulated in HCC samples.

Conclusion

The outcomes of this paper underscore the effectiveness of the clinical prognostic gene signature, established utilizing anoikis-related genes, in accurately stratifying patients. This signature holds promise in advancing the development of personalized therapy for HCC.

The oncogenic kinase TOPK upregulates in psoriatic keratinocytes and contributes to psoriasis progression by regulating neutrophils infiltration

BACKGROUND

T-LAK cell-oriented protein kinase (TOPK) strongly promotes the malignant proliferation of cancer cells and is recognized as a promising biomarker of tumor progression. Psoriasis is a common inflammatory skin disease featured by excessive proliferation of keratinocytes. Although we have previously reported that topically inhibiting TOPK suppressed psoriatic manifestations in psoriasis-like model mice, the exact role of TOPK in psoriatic inflammation and the underlying mechanism remains elusive.

METHODS

GEO datasets were analyzed to investigate the association of TOPK with psoriasis. Skin immunohistochemical (IHC) staining was performed to clarify the major cells expressing TOPK. TOPK conditional knockout (cko) mice were used to investigate the role of TOPK-specific deletion in IMQ-induced psoriasis-like dermatitis in mice. Flow cytometry was used to analyze the alteration of psoriasis-related immune cells in the lesional skin. Next, the M5-induced psoriasis cell model was used to identify the potential mechanism by RNA-seq, RT-RCR, and western blotting. Finally, the neutrophil-neutralizing antibody was used to confirm the relationship between TOPK and neutrophils in psoriasis-like dermatitis in mice.

RESULTS

We found that TOPK levels were strongly associated with the progression of psoriasis. TOPK was predominantly increased in the epidermal keratinocytes of psoriatic lesions, and conditional knockout of TOPK in keratinocytes suppressed neutrophils infiltration and attenuated psoriatic inflammation. Neutrophils deletion by neutralizing antibody greatly diminished the suppressive effect of TOPK cko in psoriasis-like dermatitis in mice. In addition, topical application of TOPK inhibitor OTS514 effectively attenuated already-established psoriasis-like dermatitis in mice. Mechanismly, RNA-seq revealed that TOPK regulated the expression of some genes in the IL-17 signaling pathway, such as neutrophils chemokines CXCL1, CXCL2, and CXCL8. TOPK modulated the expression of neutrophils chemokines via activating transcription factors STAT3 and NF-κB p65 in keratinocytes, thereby promoting neutrophils infiltration and psoriasis progression.

CONCLUSIONS

This study identified a crucial role of TOPK in psoriasis by regulating neutrophils infiltration, providing new insights into the pathogenesis of psoriasis.

PDZ-Binding Kinase, a Novel Regulator of Vascular Remodeling in Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is high blood pressure in the lungs that originates from structural changes in small resistance arteries. A defining feature of PAH is the inappropriate remodeling of pulmonary arteries (PA) leading to right ventricle failure and death. Although treatment of PAH has improved, the long-term prognosis for patients remains poor, and more effective targets are needed.

METHODS

Gene expression was analyzed by microarray, RNA sequencing, quantitative polymerase chain reaction, Western blotting, and immunostaining of lung and isolated PA in multiple mouse and rat models of pulmonary hypertension (PH) and human PAH. PH was assessed by digital ultrasound, hemodynamic measurements, and morphometry.

RESULTS

Microarray analysis of the transcriptome of hypertensive rat PA identified a novel candidate, PBK (PDZ-binding kinase), that was upregulated in multiple models and species including humans. PBK is a serine/threonine kinase with important roles in cell proliferation that is minimally expressed in normal tissues but significantly increased in highly proliferative tissues. PBK was robustly upregulated in the medial layer of PA, where it overlaps with markers of smooth muscle cells. Gain-of-function approaches show that active forms of PBK increase PA smooth muscle cell proliferation, whereas silencing PBK, dominant negative PBK, and pharmacological inhibitors of PBK all reduce proliferation. Pharmacological inhibitors of PBK were effective in PH reversal strategies in both mouse and rat models, providing translational significance. In a complementary genetic approach, PBK was knocked out in rats using CRISPR/Cas9 editing, and loss of PBK prevented the development of PH. We found that PBK bound to PRC1 (protein regulator of cytokinesis 1) in PA smooth muscle cells and that multiple genes involved in cytokinesis were upregulated in experimental models of PH and human PAH. Active PBK increased PRC1 phosphorylation and supported cytokinesis in PA smooth muscle cells, whereas silencing or dominant negative PBK reduced cytokinesis and the number of cells in the G2/M phase of the cell cycle.

CONCLUSIONS

PBK is a newly described target for PAH that is upregulated in proliferating PA smooth muscle cells, where it contributes to proliferation through changes in cytokinesis and cell cycle dynamics to promote medial thickening, fibrosis, increased PA resistance, elevated right ventricular systolic pressure, right ventricular remodeling, and PH.

Topical application of TOPK inhibitor OTS514 suppresses psoriatic progression by inducing keratinocytes cell cycle arrest and apoptosis

T-LAK cell-oriented protein kinase (TOPK) potently promotes malignant proliferation of tumour cells and is considered as a maker of tumour progression. Psoriasis is a common inflammatory skin disease characterized by abnormal proliferation of keratinocytes. However, the role of TOPK in psoriasis has not been well elucidated. This study aims to investigate the expression and role of TOPK in psoriasis, and the role of TOPK inhibitor in psoriasis attenuation. Gene Expression Omnibus datasets derived from psoriasis patients and psoriatic model mice were screened for analysis. Skin specimens from psoriasis patients were collected for TOPK immunohistochemical staining to investigate the expression and localization of TOPK. Next, psoriatic mice model was established to further confirm TOPK expression pattern. Then, TOPK inhibitor was applied to investigate the role of TOPK in psoriasis progression. Finally, cell proliferation assay, apoptosis assay and cell cycle analysis were performed to investigate the potential mechanism involved. Our study showed that TOPK was upregulated in the lesions of both psoriasis patients and psoriatic model mice, and TOPK levels were positively associated with psoriasis progression. TOPK was upregulated in psoriatic lesions and expressed predominantly by epidermal keratinocytes. In addition, TOPK levels in epidermal keratinocytes were positively correlated with epidermal hyperplasia. Furthermore, topical application of TOPK inhibitor OTS514 obviously alleviated disease severity and epidermal hyperplasia. Mechanismly, inhibiting TOPK induces G2/M phase arrest and apoptosis of keratinocytes, thereby attenuating epidermal hyperplasia and disease progression. Collectively, this study identifies that upregulation of TOPK in keratinocytes promotes psoriatic progression, and inhibiting TOPK attenuates epidermal hyperplasia and psoriatic progression.

Dysregulated FOXM1 signaling in the regulation of cancer stem cells

Since the introduction of the cancer stem cell (CSC) paradigm, significant advances have been made in understanding the functional and biological plasticity of these elusive components in malignancies. Endowed with self-renewing abilities and multilineage differentiation potential, CSCs have emerged as cellular drivers of virtually all facets of tumor biology, including metastasis, tumor recurrence/relapse, and drug resistance. The functional and biological characteristics of CSCs, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation are regulated by an array of extracellular factors, signaling pathways, and pluripotent transcriptional factors. Besides the well-characterized regulatory role of transcription factors OCT4, SOX2, NANOG, KLF4, and MYC in CSCs, evidence for the central role of Forkhead box transcription factor FOXM1 in the establishment, maintenance, and functions of CSCs is accumulating. Conventionally identified as a master regulator of the cell cycle, a comprehensive understanding of this molecule has revealed its multifarious oncogenic potential and uncovered its role in angiogenesis, invasion, migration, self-renewal, and drug resistance. This review compiles the large body of literature that has accumulated in recent years that provides evidence for the mechanisms by which FOXM1 expression promotes stemness in glioblastoma, breast, colon, ovarian, lung, hepatic, and pancreatic carcinomas. We have also compiled the data showing the association of stem cell mediators with FOXM1 using TCGA mRNA expression data. Further, the prognostic importance of FOXM1 and other stem cell markers is presented. The delineation of FOXM1-mediated regulation of CSCs can aid in the development of molecularly targeted pharmacological approaches directed at the selective eradication of CSCs in several human malignancies.

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.

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.

Omics- and Pharmacogenomic Evidence for the Prognostic, Regulatory, and Immune-Related Roles of PBK in a Pan-Cancer Cohort

PDZ-binding kinase (PBK) is known to regulate tumor progression in some cancer types. However, its relationship to immune cell infiltration and prognosis in different cancers is unclear. This was investigated in the present study by analyzing data from TCGA, GEO, GETx, TIMER, CPTAC, GEPIA2, cBioPortal, GSCALite, PROGNOSCAN, PharmacoDB, STRING, and ENCORI databases. PBK was overexpressed in most tumors including adenocortical carcinoma (hazard ratio [HR] = 2.178, p < 0.001), kidney renal clear cell carcinoma (KIRC; HR = 1.907, p < 0.001), kidney renal papillary cell carcinoma (HR = 3.024, p < 0.001), and lung adenocarcinoma (HR = 1.255, p < 0.001), in which it was associated with poor overall survival and advanced pathologic stage. PBK methylation level was a prognostic marker in thyroid carcinoma (THCA). PBK expression was positively correlated with the levels of BIRC5, CCNB1, CDC20, CDK1, DLGAP5, MAD2L1, MELK, PLK1, TOP2A, and TTK in 32 tumor types; and with the levels of the transcription factors E2F1 and MYC, which regulate apoptosis, the cell cycle, cell proliferation and invasion, tumorigenesis, and metastasis. It was also negatively regulated by the microRNAs hsa-miR-101-5p, hsa-miR-145-5p, and hsa-miR-5694. PBK expression in KIRC, liver hepatocellular carcinoma, THCA, and thymoma was positively correlated with the infiltration of immune cells including B cells, CD4+T cells, CD8⁺ T cells, macrophages, monocytes, and neutrophils. The results of the functional enrichment analysis suggested that PBK and related genes contribute to tumor development via cell cycle regulation. We also identified 20 drugs that potentially inhibit PBK expression. Thus, PBK is associated with survival outcome in a variety of cancers and may promote tumor development and progression by increasing immune cell infiltration into the tumor microenvironment. These findings indicate that PBK is a potential therapeutic target and has prognostic value in cancer treatment.

T-LAK cell-originated protein kinase (TOPK): an emerging prognostic biomarker and therapeutic target in osteosarcoma

T-lymphokine-activated killer (T-LAK) cell-originated protein kinase (TOPK) is an emerging target with critical roles in various cancers; however, its expression and function in osteosarcoma remain unexplored. We evaluated TOPK expression using RNA sequencing and gene expression data from public databases (TARGET-OS, CCLE, GTEx, and GENT2) and immunohistochemistry in an osteosarcoma tissue microarray (TMA). TOPK gene expression was significantly higher in osteosarcoma than normal tissues and directly correlated with shorter overall survival. TOPK was overexpressed in 83.3% of the osteosarcoma specimens within our TMA and all osteosarcoma cell lines, whereas normal osteoblast cells had no aberrant expression. High expression of TOPK associated with metastasis, disease status, and shorter overall survival. Silencing of TOPK with small interfering RNA (siRNA) decreased cell viability, and inhibition with the selective inhibitor OTS514 suppressed osteosarcoma cell proliferation, migration, colony-forming ability, and spheroid growth. Enhanced chemotherapeutic sensitivity and a synergistic effect were also observed with the combination of OTS514 and either doxorubicin or cisplatin in osteosarcoma cell lines. Taken together, our study demonstrated that TOPK is a potential prognostic biomarker and therapeutic target for osteosarcoma treatment.

OTS964, a TOPK Inhibitor, Is Susceptible to ABCG2-Mediated Drug Resistance

OTS964 is a potent T-LAK cell-originated protein kinase (TOPK) inhibitor. Herein, we investigated the interaction of OTS964 and multidrug resistance (MDR)-associated ATP-binding cassette sub-family G member 2 (ABCG2). The cell viability assay indicated that the effect of OTS964 is limited in cancer drug-resistant and transfected cells overexpressing ABCG2. We found that the known ABCG2 transporter inhibitor has the ability to sensitize ABCG2-overexpressing cells to OTS964. In mechanism-based studies, OTS964 shows inhibitory effect on the efflux function mediated by ABCG2, and in turn, affects the pharmacokinetic profile of other ABCG2 substrate-drugs. Furthermore, OTS964 upregulates ABCG2 protein expression, resulting in enhanced resistance to ABCG2 substrate-drugs. The ATPase assay demonstrated that OTS964 stimulates ATPase activity of ABCG2 in a concentration-dependent manner. The computational molecular docking analysis combined with results from ATPase assay suggested that OTS964 interacts with drug-binding pocket of ABCG2 and has substrate-like behaviors. Thus, OTS964 is an MDR-susceptible agent due to its interactions with ABCG2, and overexpression of ABCG2 transporter may attenuate its therapeutic effect in cancer cells.

T-LAK cell-originated protein kinase (TOPK) is a Novel Prognostic and Therapeutic Target in Chordoma

Objectives

To assess the expression, prognostic value, and functionality of T‐lymphokine‐activated killer (T‐LAK) cell‐originated protein kinase (TOPK) in chordoma pathogenesis.

Materials and Methods

TOPK expression in chordoma was assessed via immunohistochemical staining of a tissue microarray (TMA) and correlated with patient clinicopathology. TOPK expression in chordoma cell lines and fresh patient tissues was then evaluated by Western blot. TOPK small interfering RNA (siRNA) and the specific inhibitor OTS514 were applied to determine the roles of TOPK in chordoma pathogenicity. The effect of TOPK expression on chordoma cell clonogenicity was also investigated using clonogenic assays. A 3D cell culture model was utilized to mimic in vivo environment to validate the effect of TOPK inhibition on chordoma cells.

Results

TOPK was highly expressed in 78.2% of the chordoma specimens in the TMA and all chordoma cell lines. High TOPK expression significantly correlated with metastasis, recurrence, disease status and shorter overall survival. Knockdown of TOPK with specific siRNA resulted in significantly decrease chordoma cell viability. Inhibition of TOPK with OTS514 significantly inhibited chordoma cell growth and proliferation, colony‐forming capacity and ex vivo spheroid growth.

Conclusions

High expression of TOPK is an important predictor of poor prognosis in chordoma. Inhibition of TOPK resulted in significantly decrease chordoma cell proliferation and increase apoptosis. Our results indicate TOPK as a novel prognostic biomarker and therapeutic target for chordoma.

Liposomal OTS964, a TOPK inhibitor: a simple method to estimate OTS964 association with liposomes that relies on enhanced OTS964 fluorescence when bound to albumin

OTS964 is an inhibitor of T-lymphokine-activated killer cell-originated protein kinase (TOPK), a protein kinase important for mitosis and highly expressed in ovarian and lung cancers. This compound demonstrated potent anti-proliferative activity in a panel of cell lines positive for TOPK; however, when administered to mouse xenograft models, adverse hematopoietic toxicities were observed. To overcome this problem, OTS964 was encapsulated into liposomes and a liposomal formulation of OTS964 is now considered a lead candidate for clinical development. To support clinical development of this formulation, it is critically important to define assays that can easily distinguish between free and liposomal OTS964. Here, we develop a new assay to determine liposomal OTS964 encapsulation (percentage of drug associated with the liposomes) and OTS964 that is dissociated from the liposomes (percentage of drug released from liposomes) by monitoring the enhanced OTS964 fluorescence after its binding to albumin. The optical properties of OTS964 were investigated and three absorbance peaks were identified (235 nm, 291 nm, and 352 nm). Fluorescence was observed at 350 nm (excitation) and 470 nm (emission). Interestingly, the fluorescence of OTS964 increased 18-fold in the presence of serum proteins and more specifically albumin. This phenomenon was used to discriminate between the amounts of drug associated with the liposomes or released from the liposomes. Controls consisting of liposomal OTS964 permeabilized with saponins or octyl glucopyranoside served to confirm that drug release could be monitored by albumin-associated increases in fluorescence. The OTS964 liposomal formulation proved to be very stable with less than 10% release after 4 days in phosphate-buffered saline at 37 °C. The quantity of drug associated with the liposomal surface but not inside the liposomes could also be estimated using this approach. These studies present a novel approach to characterize liposomal release of OTS964, in real time and in a non-invasive manner while acquiring additional information about the spatial distribution of liposomal drug.

Gossypetin Inhibits Solar-UV Induced Cutaneous Basal Cell Carcinoma Through Direct Inhibiting PBK/TOPK Protein Kinase

BACKGROUND

Skin photoaging, skin inflammation and skin cancer are related with excessive exposure to solar UV. PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK), a member of the serine/threonine protein kinase, which regulates the signaling cascades of p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal regulated kinase 1/2 (ERK1/2). PBK/TOPK plays a significant role in solar-UV-induced cutaneous basal cell carcinoma (BCC), and targeting PBK/TOPK can be supposed to treat and prevent cutaneous BCC.

METHODS

The pathological feature and the expression level of PBK/TOPK in cutaneous BCC tissues of human were studied in clinical samples. SUV-induced the phosphorylation of p38 MAPK and ERK1/2 were demonstrated ex vivo. Moreover, the interaction between Gossypetin and PBK/TOPK were detected by in vitro kinase assay and Microscale thermophoresis (MST) assay. Furthermore, the effect of Gossypetin to solar UV-induced the activity of PBK/TOPK were detected ex vivo and in vivo.

RESULTS

The clinical samples showed that the expression levels of PBK/TOPK, phosphor-p38 MAPK and phosphor- ERK1/2 were up-regulated in cutaneous BCC tissues of human. The expression of phosphor-p38 MAPK or phosphor-ERK1/2 increased in a dose and time dependent manner after solar UV treatment in HaCaT cells. MTT cytotoxicity assay results showed that Gossypetin has no effect on HaCaT cells. In vitro kinase assay and MST assay results showed that Gossypetin bound with PBK/TOPK and suppressed PBK/TOPK activity. Ex vivo results showed Gossypetin inhibited solar UV-induced phosphorylation of PBK/TOPK, p38 MAPK, ERK1/2 and H2AX by suppressing PBK/TOPK activity. In vivo test results indicated that Gossypetin suppressed solar UV-induced increase of PBK/TOPK, phosphor-p38 MAPK, phosphor-ERK1/2 and phosphor- H2AX in SKH-1 hairless mice.

CONCLUSION

Our data demonstrated that Gossypetin can alleviate solar-UV-induced cutaneous BCC by blocking PBK/TOPK, and Gossypetin could be a remarkable agent for treating solar-UV induced cutaneous basal cell carcinoma.

In Vitro Employment of Recombinant Taenia solium Calreticulin as a Novel Strategy Against Breast and Ovarian Cancer Stem-like Cells

BACKGROUND AND AIMS

Calreticulin is a chaperone and master regulator of intracellular calcium homeostasis. Several additional functions have been discovered. Human and parasite calreticulin have been shown to suppress mammary tumor growth in vivo. Here, we explored the capacity of recombinant Taenia solium calreticulin (rTsCRT) to modulate cancer cell growth in vitro.

METHODS

We used different concentrations of rTsCRT to treat cancer cell lines and analyzed viability and colony formation capacity. We also tested the combination of the IC₂₀ or IC₅₀ doses of rTsCRT and of the chemotherapeutic drug 5-fluorouracil on MCF7 and SKOV3 cell lines. As a control, the non-tumorigenic cell line MCF10-A was employed. The effect of the drug combinations was also assessed in cancer stem-like cells. Additionally, scavenger receptor ligands were employed to identify the role of this receptor in the rTsCRT anti-tumoral effect.

RESULTS

rTsCRT has a dose-dependent in vitro anti-tumoral effect, being SKOV3 the most sensitive cell line followed by MCF7. When rTsCRT/5-fluorouracil were used, MCF7 and SKOV3 showed a 60% reduction in cell viability; colony formation capacity was also diminished. Treatment of cancer stem-like cells from MCF7 showed a higher reduction in cell viability, while those from SKOV3 were more sensitive to colony disaggregation. Finally, pharmacological inhibition of the scavenger receptor, abrogated the reduction in viability induced by rTsCRT in both the parental and stem-like cells.

CONCLUSION

Our data suggest that rTsCRT alone or in combination with 5-fluorouracil inhibits the growth of breast and ovarian cancer cell lines through its interaction with scavenger receptors.

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.

Protective effects of glycycoumarin on liver diseases

Licorice, an edible and medicinal plant, has long been used to treat various diseases, including liver diseases. Glycycoumarin (GCM) is a representative coumarin compound in licorice with favorable bioavailability feature. Recent studies by us demonstrated that GCM is highly effective against alcoholic liver disease, nonalcoholic fatty liver disease, acetaminophen-induced hepatotoxicity, and liver cancer through mechanisms involved in activation of Nrf2 antioxidant system, stimulation of AMPK-mediated energy homeostasis, induction of autophagy degradation process, and inhibiting oncogenic kinase T-lymphokine-activated killer cell-originated protein kinase activity. In this review, we summarize the findings on the hepatoprotective effect of GCM, discuss the signaling pathways underlying GCM-induced protective effect on liver diseases, and propose the issues that need to be addressed to promote further development of GCM as a clinically useful hepatoprotective agent.

Potent anti-myeloma activity of the TOPK inhibitor OTS514 in pre-clinical models

Multiple myeloma (MM) continues to be considered incurable, necessitating new drug discovery. The mitotic kinase T‐LAK cell‐originated protein kinase/PDZ‐binding kinase (TOPK/PBK) is associated with proliferation of tumor cells, maintenance of cancer stem cells, and poor patient prognosis in many cancers. In this report, we demonstrate potent anti‐myeloma effects of the TOPK inhibitor OTS514 for the first time. OTS514 induces cell cycle arrest and apoptosis at nanomolar concentrations in a series of human myeloma cell lines (HMCL) and prevents outgrowth of a putative CD138⁺ stem cell population from MM patient‐derived peripheral blood mononuclear cells. In bone marrow cells from MM patients, OTS514 treatment exhibited preferential killing of the malignant CD138⁺ plasma cells compared with the CD138⁻ compartment. In an aggressive mouse xenograft model, OTS964 given orally at 100 mg/kg 5 days per week was well tolerated and reduced tumor size by 48%‐81% compared to control depending on the initial graft size. FOXO3 and its transcriptional targets CDKN1A (p21) and CDKN1B (p27) were elevated and apoptosis was induced with OTS514 treatment of HMCLs. TOPK inhibition also induced loss of FOXM1 and disrupted AKT, p38 MAPK, and NF‐κB signaling. The effects of OTS514 were independent of p53 mutation or deletion status. Combination treatment of HMCLs with OTS514 and lenalidomide produced synergistic effects, providing a rationale for the evaluation of TOPK inhibition in existing myeloma treatment regimens.

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.

Cell growth inhibition by 3-deoxysappanchalcone is mediated by directly targeting the TOPK signaling pathway in colon cancer

BACKGROUND

Colorectal cancer is one of the most common causes of cancer death worldwide. Unfortunately, chemotherapies are limited due to many complications and development of resistance and recurrence. The T-lymphokine-activated killer cell-originated protein kinase (TOPK) is highly expressed and activated in colon cancer, and plays an important role in inflammation, proliferation, and survival of cancer cells. Therefore, suppressing TOPK activity and its downstream signaling cascades is considered to be a rational therapeutic/preventive strategy against colon cancers.

PURPOSE

3-Deoxysappanchalcone (3-DSC), a component of Caesalpinia sappan L., is a natural oriental medicine. In this study, we investigated the effects of 3-DSC on colon cancer cell growth and elucidated its underlying molecular mechanism of targeting TOPK.

STUDY DESIGN AND METHODS

To evaluate the effects of 3-DSC against colon cancer, we performed cell proliferation assays, propidium iodide- and annexin V-staining analyses and Western blotting. Targeting TOPK by 3-DSC was identified by a kinase-binding assay and computational docking models.

RESULTS

3-DSC inhibited the kinase activity of TOPK, but not mitogen-activated protein kinase (MEK). The direct binding of 3-DSC with TOPK was explored using a computational docking model and binding assay in vitro and ex vivo. 3-DSC inhibited colon cancer cell proliferation and anchorage-independent cell growth, and induced G2/M cell cycle arrest and apoptosis. Treatment of colon cancer cells with 3-DSC induced expression of protein that are involved in cell cycle (cyclin B1) and apoptosis (cleaved-PARP, cleaved-caspase-3, and cleaved-caspase-7), and suppressed protein expressions of extracellular signal-regulated kinase (ERK)-1/2, ribosomal S6 kinase (RSK), and c-Jun, which are regulated by the upstream kinase, TOPK.

CONCLUSION

3-DSC suppresses colon cancer cell growth by directly targeting the TOPK- mediated signaling pathway.

The multifaceted roles of FOXM1 in pulmonary disease

Forkhead box M1 (FOXM1), a transcriptional regulator of G1/S and G2/M transition and M phase progression in the cell cycle, plays a principal role in many physiological and pathological processes. A growing number of studies have focused on the relationship between abnormal FOXM1 expression and pulmonary diseases, such as lung cancer, chronic obstructive pulmonary disease (COPD), asthma, acute lung injury (ALI), pulmonary fibrosis, and pulmonary arterial hypertension (PAH). These studies indicate that the FOXM1 regulatory network is a major predictor of poor outcomes, especially in lung cancer, and provide novel insight into various pulmonary diseases. For the first time, this review summarizes the mechanistic relationship between FOXM1 dysregulation and pulmonary diseases, the benefits of targeting abnormal FOXM1 expression, and the questions that remain to be addressed in the future.

Baicalin suppresses lung cancer growth by targeting PDZ-binding kinase/T-LAK cell-originated protein kinase

Baicalin is the main bioactive component extracted from the traditional Chinese medicine Baical Skullcap Root, and its anti-tumor activity has been studied in previous studies. PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK), a serine/threonine protein kinase, is highly expressed in many cancer cells and stimulates the tumorigenic properties, and so, it is a pivotal target for agent to cure cancers. We reported for the first time that baicalin suppressed PBK/TOPK activities by directly binding with PBK/TOPK in vitro and in vivo. Ex vivo studies showed that baicalin suppressed PBK/TOPK activity in JB6 Cl41 cells and H441 lung cancer cells. Moreover, knockdown of PBK/TOPK in H441 cells decreased their sensitivity to baicalin. In vivo study indicated that injection of baicalin in H441 tumor-bearing mice effectively suppressed cancer growth. The PBK/TOPK downstream signaling molecules Histone H3 and ERK2 in tumor tissues were also decreased after baicalin treatment. Taken together, baicalin can inhibit proliferation of lung cancer cells as a PBK/TOPK inhibitor both in vitro and in vivo.

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.

Novel selective TOPK inhibitor SKLB-C05 inhibits colorectal carcinoma growth and metastasis

The mitogen-activated protein kinase (MAPK) signaling pathway member T-LAK cell-originated protein kinase/PDZ-binding kinase (TOPK/PBK) is closely involved in tumorigenesis and progression. Its overexpression in colorectal carcinoma (CRC) exacerbates tumor malignancy, promotes metastasis and results in dismal prognosis. Therefore, targeting TOPK is a promising approach for CRC therapy. Here, we report the development of a TOPK selective inhibitor SKLB-C05, with subnanomolar inhibitory potency. In vitro, SKLB-C05 exhibited excellent cytotoxicity and anti-migration and invasion activity on TOPK high-expressing CRC cells and induced cell apoptosis. These activities could attribute to its inhibition of TOPK downstream signaling including extracellular signal-regulated kinase 1/2 (ERK1/2), p38, and c-Jun N-terminal kinase 1, 2, and 3 (JNK1/2/3), as well as downregulation of FAK/Src- MMP signaling. Furthermore, SKLB-C05 disrupted cell mitosis and blocked CRC cell cycle. In vivo, oral administration of SKLB-C05 at concentrations of 20 and 10 mg kg^-1·day^-1 dramatically attenuated CRC tumor xenograft growth and completely suppressed hepatic metastasis of HCT116 cells, respectively. Thus, these findings suggest that SKLB-C05 is a specific TOPK inhibitor with potent anti-CRC oncogenic activity in vitro and in vivo.

Design, synthesis and biological evaluation of novel 1-phenyl phenanthridin-6(5H)-one derivatives as anti-tumor agents targeting TOPK

T-lymphokine-activated killer cell-originated protein kinase (TOPK) is a serine-threonine mitogen-activated protein kinase that is highly expressed in many types of human cancer. Due to its important role in cancer progression, TOPK is becoming an attractive target in chemotherapeutic drug design. In this study, a series of 1-phenyl phenanthridin-6(5H)-one derivatives have been identified as a novel chemical class of TOPK inhibitors. Some of them displayed very potent anti-cancer activity with IC₅₀s less than 100 nM, superior than reference compound OTS964. The most potent compound, 9g suppressed the growth of cancer cells by apoptosis and specifically inhibited the activities of TOPK. Oral administration of 9g effectively suppressed tumor growth with TGI >79.7% in colorectal cancer xenograft models, demonstrating superior efficacy compared to OTS964. Pharmacokinetic studies reveal its good oral bioavailability. Our findings therefore show that 9g is a specific inhibitor of TOPK both in vitro and in vivo that may be further developed as a potential therapeutic agent against colorectal cancer.

T-LAK cell-originated protein kinase (TOPK): an emerging target for cancer-specific therapeutics

'Targeted' or 'biological' cancer treatments rely on differential gene expression between normal tissue and cancer, and genetic changes that render tumour cells especially sensitive to the agent being applied. Problems exist with the application of many agents as a result of damage to local tissues, tumour evolution and treatment resistance, or through systemic toxicity. Hence, there is a therapeutic need to uncover specific clinical targets which enhance the efficacy of cancer treatment whilst minimising the risk to healthy tissues. T-LAK cell-originated protein kinase (TOPK) is a MAPKK-like kinase which plays a role in cell cycle regulation and mitotic progression. As a consequence, TOPK expression is minimal in differentiated cells, although its overexpression is a pathophysiological feature of many tumours. Hence, TOPK has garnered interest as a cancer-specific biomarker and biochemical target with the potential to enhance cancer therapy whilst causing minimal harm to normal tissues. Small molecule inhibitors of TOPK have produced encouraging results as a stand-alone treatment in vitro and in vivo, and are expected to advance into clinical trials in the near future. In this review, we present the current literature pertaining to TOPK as a potential clinical target and describe the progress made in uncovering its role in tumour development. Firstly, we describe the functional role of TOPK as a pro-oncogenic kinase, followed by a discussion of its potential as a target for the treatment of cancers with high-TOPK expression. Next, we provide an overview of the current preclinical progress in TOPK inhibitor discovery and development, with respect to future adaptation for clinical use.

T-lymphokine-activated killer cell-originated protein kinase (TOPK) as a prognostic factor and a potential therapeutic target in glioma

TOPK is overexpressed in various types of cancer and associated with poor outcomes in different types of cancer. In this study, we first found that the expression of T-lymphokine-activated killer cell-originated protein kinase (TOPK) was significantly higher in Grade III or Grade IV than that in Grade II in glioma (P = 0.007 and P < 0.001, respectively). Expression of TOPK was positively correlated with Ki67 (P < 0.001). Knockdown of TOPK significantly inhibited cell growth, colony formation and increased sensitivities to temozolomide (TMZ) in U-87 MG or U-251 cells, while TOPK overexpression promoted cell growth and colony formation in Hs 683 or A-172 cells. Glioma patients expressing high levels of TOPK have poor survival compared with those expressing low levels of TOPK in high-grade or low-grade gliomas (hazard ratio = 0.2995; 95% CI, 0.1262 to 0.7108; P = 0.0063 and hazard ratio = 0.1509; 95% CI, 0.05928 to 0.3842; P < 0.0001, respectively). The level of TOPK was low in TMZ-sensitive patients compared with TMZ-resistant patients (P = 0.0056). In TMZ-resistant population, patients expressing high TOPK have two months’ shorter survival time than those expressing low TOPK. Our findings demonstrated that TOPK might represent as a promising prognostic and predictive factor and potential therapeutic target for glioma.

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.

TOPK (T-LAK cell-originated protein kinase) inhibitor exhibits growth suppressive effect on small cell lung cancer

T-lymphokine-activated killer cell-originated protein kinase (TOPK) plays critical roles in cancer cell proliferation as well as maintenance of cancer stem cells (CSC). Small cell lung cancer (SCLC) has highly aggressive phenotype, reveals early spread to distant sites, and results in dismal prognosis with little effective treatment. In this study, we demonstrate that TOPK expression was highly upregulated in both SCLC cell lines and primary tumors. Similar to siRNA-mediated TOPK knockdown effects, treatment with a potent TOPK inhibitor, OTS514, effectively suppressed growth of SCLC cell lines (IC₅₀ ; 0.4-42.6 nM) and led to their apoptotic cell death. TOPK inhibition caused cell morphologic changes in SCLC cells, elongation of intercellular bridges caused by cytokinesis defects or neuronal protrusions induced by neuronal differentiation in a subset of CSC-like SCLC cells. Treatment with OTS514 suppressed forkhead box protein M1 (FOXM1) activity, which was involved in stemness of CSC. Furthermore, OTS514 treatment reduced CD90-positive SCLC cells and showed higher cytotoxic effect against lung sphere-derived CSC-like SCLC cells. Collectively, our results suggest that targeting TOPK is a promising approach for SCLC therapy.