Requirement of T-lymphokine-activated killer cell-originated protein kinase for TRAIL resistance of human HeLa cervical cancer cells

TOPK inhibits TNF-α-induced granulosa cell apoptosis via regulation of SIRT1/p53

T-LAK cell originated protein kinase (TOPK) has been shown to regulate proliferation, invasion or migration of various cancer cells. However, the role of TOPK in follicle environments remains unknown. Here we reveal that TOPK inhibits TNF-α-induced human granulosa COV434 cell apoptosis. The expression of TOPK were increased in COV434 cells in response to TNF-α. TOPK inhibition also decreased TNF-α-induced SIRT1 expression but promoted TNF-α-induced p53 acetylation and expression of PUMA or NOXA. Accordingly, TOPK inhibition attenuated TNF-α-mediated SIRT1 transcriptional activity. In addition, SIRT1 inhibition augmented acetylation of p53 or expression of PUMA and NOXA in response to TNF-α, leading to COV434 cell apoptosis. We conclude that TOPK suppresses TNF-α-induced COV434 granulosa cell apoptosis via regulation of p53/SIRT1 axis, suggesting a potential role of TOPK in regulation of ovarian follicular development.

Immunometabolic and potential tumor-promoting changes in 3D cervical cell models infected with bacterial vaginosis-associated bacteria

Specific bacteria of the human microbiome influence carcinogenesis at diverse anatomical sites. Bacterial vaginosis (BV) is the most common vaginal disorder in premenopausal women that is associated with gynecologic sequelae, including cervical cancer. BV-associated microorganisms, such as Fusobacterium, Lancefieldella, Peptoniphilus, and Porphyromonas have been associated with gynecologic and other cancers, though the pro-oncogenic mechanisms employed by these bacteria are poorly understood. Here, we integrated a multi-omics approach with our three-dimensional (3-D) cervical epithelial cell culture model to investigate how understudied BV-associated bacteria linked to gynecologic neoplasia influence hallmarks of cancer in vitro. Lancefieldella parvulum and Peptoniphilus lacrimalis elicited robust proinflammatory responses in 3-D cervical cells. Fusobacterium nucleatum and Fusobacterium gonidiaformans modulated metabolic hallmarks of cancer corresponding to accumulation of 2-hydroxyglutarate, pro-inflammatory lipids, and signs of oxidative stress and genotoxic hydrogen sulfide. This study provides mechanistic insights into how gynecologic cancer-associated bacteria might facilitate a tumor-promoting microenvironment in the human cervix.

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.

PBK promotes aggressive phenotypes of cervical cancer through ERK/c-Myc signaling pathway

Cervical cancer is the fourth most frequent cancer in women worldwide. PDZ-binding kinase (PBK) is proven to promote the malignant behaviors of various carcinomas. However, its functional roles and oncogenic mechanisms in cervical cancer are poorly understood. In this study, we reported that PBK was highly expressed in cervical cancer tissues. PBK promoted the proliferation, metastasis, and cisplatin resistance of cervical cancer cells. OTS514, a specific PBK inhibitor, could significantly suppress proliferation and metastasis of cervical cancer cells in vitro and in a xenograft model. Besides, OTS514 could enhance cisplatin-based chemosensitivity in cervical cancer cells. Mechanistically, PBK promoted the expression and stabilization of c-Myc through phosphorylating ERK1/2. OTS514 suppressed the phosphorylation of ERK1/2 and the transcriptional activity of c-Myc. Furthermore, inhibition of the ERK signal pathway by U0126 reversed the increased proliferation and metastasis induced by overexpression of PBK. Exogenous expression of c-Myc counteracted the decreased proliferation and metastasis evoked by knockdown of PBK. In conclusion, PBK promoted the malignant progression of cervical cancer through ERK/c-Myc signal pathway. PBK might be a promising molecular target for cervical cancer treatment.

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.

Activation of NF-κB by TOPK upregulates Snail/Slug expression in TGF-β1 signaling to induce epithelial-mesenchymal transition and invasion of breast cancer cells

TGF-β1 is known to induce epithelial-mesenchymal transition (EMT), which is a prerequisite for cancer cell invasion. Here we reveal that TOPK upregulates EMT and invasion of human breast cancer MDA-MB-231 or Hs578T cells via NF-κB-dependent Snail/Slug in TGF-β1 signaling. Endogenous TOPK expression was significantly increased in response to TGF-β1 and TOPK knockdown mitigated TGF-β1-induced breast cancer cell invasion. Interestingly, TOPK knockdown restored TGF-β1 suppression of E-cadherin expression and markedly reduced N-cadherin induced by TGF-β1. Also, NF-κB activity or expression of EMT markers Snail and Slug induced by TGF-β1 was decreased by TOPK knockdown. Meanwhile, knockdown of Snail or TOPK attenuated TGF-β1-induced breast cancer cell invasion. Taken, we conclude that TOPK mediates TGF-β1-induced EMT and invasion in breast cancer cells via NF-κB/Snail signaling, suggesting novel role of TOPK as therapeutic target in TGF-β1-mediated breast cancer development.

PBK attenuates paclitaxel-induced autophagic cell death by suppressing p53 in H460 non-small-cell lung cancer cells

PDZ‐binding kinase (PBK) has previously been shown to mediate chemoresistance of cancer cells to anticancer drugs. However, it remains unclear how PBK regulates paclitaxel‐induced cancer cell death. Here, we demonstrate that PBK hinders paclitaxel‐mediated autophagic cell death in H460 non‐small‐cell lung cancer cells. PBK knockdown increased apoptosis, autophagy, p53 level, and LC3 puncta upon paclitaxel treatment. Moreover, p53 expression facilitated an increase in the LC3‐II/LC3‐I ratio in response to paclitaxel, and PBK knockdown augmented paclitaxel‐mediated p53 transcriptional activity. Meanwhile, paclitaxel induced PBK‐mediated p53 nuclear export and its subsequent ubiquitination in control cells, but not in PBK knockdown cells. We conclude that PBK hampers paclitaxel‐induced autophagic cell death by suppressing p53, suggesting a potential role of PBK in p53‐mediated H460 cell death.

TOPK promotes epithelial-mesenchymal transition and invasion of breast cancer cells through upregulation of TBX3 in TGF-β1/Smad signaling

TOPK has been suggested to contribute to invasion of lung, prostate, gastric, pancreatic or breast cancer cells. However, how TOPK mediates TGF-β1/Smad signaling leading to epithelial-mesenchymal transition (EMT) and invasion of breast cancer cells remains unknown. Here we report that TOPK upregulates T-box transcription factor TBX3 to enhance TGF-β1-induced EMT and invasion of MDA-MB-231 breast cancer cells. Expression of endogenous TOPK was promoted by TGF-β1 treatment of MDA-MB-231 cells time-dependently. In addition, knockdown of TOPK attenuated TGF-β1-induced phosphorylation or transcriptional activity of Smad3. Meanwhile, levels of both mRNA and protein of TBX3 induced by TGF-β1 were abolished by TOPK depletion. Also, knockdown of TBX3 inhibited TGF-β1 induction of EMT-related genes Snail, Slug or Fibronectin. Furthermore, ablation of TOPK or TBX3 suppressed TGF-β1-induced MDA-MB-231 cell invasion. Collectively, we conclude that TOPK positively regulates TBX3 in TGF-β1/Smad signaling pathway, thereby enhancing EMT and invasion of breast cancer cells, implying a mechanistic role of TOPK in TGF-β1/Smad signaling.

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.

Proton pump inhibitor ilaprazole suppresses cancer growth by targeting T-cell-originated protein kinase

T-cell-originated protein kinase (TOPK) is highly and frequently expressed in various cancer tissues and plays an indispensable role in the mitosis of cancer cells, and therefore, it is an important target for drug treatment of tumor. Ilaprazole was identified to be a potent TOPK inhibitor. The data indicated that ilaprazole inhibited TOPK activities with high affinity and selectivity. In vitro studies showed that ilaprazole inhibited TOPK activities in HCT116, ES-2, A549, SW1990 cancer cells. Moreover, knockdown of TOPK in these cells decreased their sensitivities to ilaprazole. Results of an in vivo study demonstrated that gavage of ilaprazole in HCT116 colon tumor-bearing mice effectively suppressed cancer growth. The TOPK downstream signaling molecule phospho-histone H3 in tumor tissues was also decreased after ilaprazole treatment. Our results suggested that ilaprazole inhibited the cancer growth by targeting TOPK both in vitro and in vivo.

Role of TOPK in lipopolysaccharide-induced breast cancer cell migration and invasion

Inflammation has been known to be linked to invasion or metastasis of breast cancer, which has poor prognosis, although the regulatory mechanism remains to be undiscovered. Here we show that T-LAK cell-originated protein kinase (TOPK) mediates pro-inflammatory endotoxin lipopolysaccharide (LPS)-induced breast cancer cell migration and invasion. The mRNA or protein level of TOPK, toll- like receptor4 (TLR4), interleukin (IL)-6, vascular endothelial growth factor (VEGF) or matrix metalloproteinase9 (MMP9) genes related to TLR4 signaling or tumor progression was induced by LPS treatment in MCF7 breast cancer cells, but the induction was abolished by stable knocking down of TOPK in MCF7 cells. Also, TOPK depletion decreased LPS-induced phosphorylation of p38, but not ERK and JNK among mitogen-activated protein kinases (MAPKs). On the other hand, we revealed that TOPK is essential for transcriptional activity of NF-κB or MMP9 promoter triggered by LPS. The induced promoter activity of NF-κB or MMP9 but not AP-1 was inhibited by knocking down of TOPK. Furthermore, we demonstrated that inhibitor of TOPK or MMP9 as well as MMP9 siRNA efficiently blocked LPS-induced migration or invasion of breast cancer cell lines. Interestingly, both of expression of TOPK and TLR4 were markedly increased in high-grade breast cancer. Collectively, we conclude that TOPK functions as a key mediator of LPS/TLR4-induced breast cancer cell migration and invasion through regulation of MMP9 expression or activity, implying a potential role of TOPK as a therapeutic target linking LPS-induced inflammation to breast cancer development.

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.

Identification of the oncogenic kinase TOPK/PBK as a master mitotic regulator of C2H2 zinc finger proteins

TOPK/PBK is an oncogenic kinase upregulated in most human cancers and its high expression correlates with poor prognosis. TOPK is known to be activated by Cdk1 and needed for mitotic cell division; however, its mitotic functions are not yet fully understood. In this study, we show that TOPK plays a global mitotic role by simultaneously regulating hundreds of DNA binding proteins. C2H2 zinc finger proteins (ZFPs) constitute the largest family of human proteins. All C2H2 ZFPs contain a highly conserved linker sequence joining their multi-zinc finger domains. We have previously shown that phosphorylation of this conserved motif serves as a global mechanism for the coordinate dissociation of C2H2 ZFPs from condensing chromatin, during mitosis. Here, using a panel of kinase inhibitors, we identified K252a as a potent inhibitor of mitotic ZFP linker phosphorylation. We generated a biotinylated form of K252a and used it to purify candidate kinases. From these candidates we identified TOPK/PBK, in vitro and in vivo, as the master ZFP linker kinase. Furthermore, we show precise temporal correlation between TOPK activating phosphorylation by Cdk1 and linker phosphorylation in mitosis. The identification of this fundamental role of TOPK underscores its significance as a promising novel target of cancer therapeutics.

Pc2-mediated SUMOylation of WWOX is essential for its suppression of DU145 prostate tumorigenesis

Tumor suppressor WW domain-containing oxidoreductase (WWOX) is depleted in various cancer types. Here we report that WWOX is modified by small ubiquitin-like modifier (SUMO) proteins and represses DU145 prostate cancer tumorigenesis in a SUMOylation-dependent manner. Ectopic WWOX was shown to associate with SUMO2/3 or E2 Ubc9. Furthermore, we revealed that WWOX SUMOylation was promoted by E3 ligase polycomb2 (Pc2), and that WWOX associated with Pc2. Meanwhile, anisomycin-induced activator protein-1 (AP-1) activity was markedly diminished by co-expression of SUMO and WWOX. Also, WWOX wild type (WT), but not WWOX SUMO mutant (K176A) markedly reduced both DU145 prostate cancer cell proliferation and xenograft tumorigenesis. Collectively, our findings demonstrate that SUMO modification of WWOX is essential for its suppressive activity for DU145 prostate cancer tumorigenesis.

Targeting death receptors for TRAIL by agents designed by Mother Nature

Selective killing of cancer cells is one of the major goals of cancer therapy. Although chemotherapeutic agents are being used for cancer treatment, they lack selectivity toward tumor cells. Among the six different death receptors (DRs) identified to date, DR4 and DR5 are selectively expressed on cancer cells. Therefore, unlike chemotherapeutic agents, these receptors can potentially mediate selective killing of tumor cells. In this review we outline various nutraceuticals derived from 'Mother Nature' that can upregulate DRs and thus potentiate apoptosis. These nutraceuticals increase tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of cancer cells through different mechanisms. First, nutraceuticals have been found to induce DRs through the upregulation of various signaling molecules. Second, nutraceuticals can downregulate tumor cell-survival pathways. Third, nutraceuticals alone have been found to activate cell-death pathways. Although both TRAIL and agonistic antibodies against DR4 and DR5 are in clinical trials, combination with nutraceuticals is likely to boost their anticancer potential.

Activation of TOPK by lipopolysaccharide promotes induction of inducible nitric oxide synthase through NF-κB activity in leukemia cells

T-LAK cell-originated protein kinase (TOPK) is known to be involved in tumorigenesis or cancer progression. However, the role of TOPK in inflammatory response remains elusive. Here we show that TOPK positively regulates inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) production in response to lipopolysaccharide (LPS). In TOPK-depleted cells, the iNOS expression was shown to be greatly abolished. Also, we revealed that LPS treatment augmented the expression and activity of TOPK, the interaction of TOPK with IκBα, and promoted TOPK kinase activity against IκBα. Moreover, NF-κB or iNOS promoter-driven transcriptional activity in response to LPS was markedly reduced by knocking down of TOPK or deletion of NF-κB sites. On the other hand, endogenous TOPK level was expressed very lowly in bone marrow-derived macrophage (BMDM) prepared from Toll-like receptor 4 (TLR4) knockout mice, compared to BMDM from wild type (WT) mice. Collectively, these findings demonstrate that TOPK upregulates iNOS gene expression in T cell leukemia Jurkat cells or macrophage leukemic Raw 264.7 cells via NF-κB activation in response to LPS, and might act as a critical effector in LPS/TLR4-mediated signaling cascade, suggesting a possible role of TOPK in inflammatory response or inflammation-related diseases.

Apoptosis induced by copper oxide quantum dots in cultured C2C12 cells via caspase 3 and caspase 7: a study on cytotoxicity assessment

We report herein the synthesis and characterization of copper oxide quantum dots and their cytotoxic impact on mouse C2C12 cells. The utilized CuO quantum dots were prepared by the one-pot wet chemical method using copper acetate and hexamethylenetetramine as precursors. The physicochemical characterization of the synthesized CuO quantum dots was carried out using X-ray diffraction, energy-dispersive X-ray analysis, and transmission electron microscopy. To examine the in vitro cytotoxicity, C2C12 cell lines were treated with different concentrations of as-prepared quantum dots and the viability of cells was analyzed using Cell Counting Kit-8 assay at regular time intervals. The morphology of the treated C2C12 cells was observed under a phase-contrast microscope, whereas the quantification of cell viability was carried out via confocal laser scanning microscopy. To gain insight into the mechanism of cell death, we examined the effect of CuO quantum dots on the candidate genes such as caspases 3 and 7, which are key mediators of apoptotic events. In vitro investigations of the biological effect of CuO quantum dots have shown that it binds genomic DNA, decreases significantly the viability of cells in culture in a concentration (10-20 μg/mL) dependent manner, and inhibits mitochondrial caspases 3 and 7. To sum up, the elucidation of the pathways is to help in understanding CuO quantum dot-induced effects and evaluating CuO quantum dot-related hazards to human health.

Phosphorylation of IκBα at serine 32 by T-lymphokine-activated killer cell-originated protein kinase is essential for chemoresistance against doxorubicin in cervical cancer cells

T-lymphokine-activated killer cell-originated protein kinase (TOPK) is known to be up-regulated in cancer cells and appears to contribute to cancer cell proliferation and survival. However, the molecular mechanism by which TOPK regulates cancer cell survival still remains elusive. Here we show that TOPK directly interacted with and phosphorylated IκBα at Ser-32, leading to p65 nuclear translocation and NF-κB activation. We also revealed that doxorubicin promoted the interaction between nonphosphorylated or phosphorylated TOPK and IκBα and that TOPK-mediated IκBα phosphorylation was enhanced in response to doxorubicin. Also, exogenously overexpressed TOPK augmented transcriptional activity driven by either NF-κB or inhibitor of apoptosis protein 2 (cIAP2) promoters. On the other hand, NF-κB activity including IκBα phosphorylation and p65 nuclear translocation, as well as cIAP2 gene expression, was markedly diminished in TOPK knockdown HeLa cervical cancer cells. Moreover, doxorubicin-mediated apoptosis was noticeably increased in TOPK knockdown HeLa cells, compared with control cells, which resulted from caspase-dependent signaling pathways. These results demonstrate that TOPK is a molecular target of doxorubicin and mediates doxorubicin chemoresistance of HeLa cells, suggesting a novel mechanism for TOPK barrier of doxorubicin-mediated cervical cancer cell apoptosis.

Cell death in HeLa mediated by thermoplastic polyurethane with co-immobilized IFN-γ plus TNF-α

In order to prohibit the toxicity of free IFN-γ plus TNF-α in treating human cervical cancer HeLa cells, two kinds of thermoplastic polyurethane (polyester/polyether) biomaterials with co-immobilized IFN-γ plus TNF-α on the surfaces are prepared. The programmed cell death of HeLa induced by these biomaterials is investigated. The surface modification of these biomaterials with co-immobilized IFN-γ plus TNF-α is performed by the photo-immobilization method, and the surface structures are characterized by various techniques. The cell morphology, cell mortality, cell cycle arrest, and functional status of caspases, upon the treatment by these biomaterials, are characterized. The results show that the as-prepared biomaterials have high inhibition activity against the growth of HeLa cells. The HeLa cells mediated by the two kinds of biomaterials are mainly arrested in the G(1) phase, while those cells mediated directly by free IFN-γ plus TNF-α are mainly arrested in the S phase. It is suggested that the programmed cell death mechanism induced by these two kinds of biomaterials is both caspase-dependent and caspase-independent. Our data provide the knowledge of microscopic surface structures and cell biology basis for synthesizing the thermoplastic polyurethane biomaterials with co-immobilized IFN-γ plus TNF-α, which are promising for novel therapeutics (e.g. drug cup) design for cervical cancer patients.