T-LAK Cell-originated Protein Kinase Inhibitor Research Articles

A Lead Optimization of TOPK Inhibitors Using Complementary Computational and Synthetic Approaches

Background: T-LAK cell-originated protein kinase (TOPK), a member of the MEK3/6-related mitogen-activated protein kinase kinase (MAPKK) family, is highly overexpressed in various cancers. This overexpression is linked to the mitotic phase of the cell cycle, highlighting its potential as a prognostic marker and therapeutic target. Unlike many other cancer targets, TOPK exhibits limited expression or is even absent in non-proliferative tissues. Therefore, TOPK inhibitors hold promise for developing anticancer agents with high selectivity and specificity for cancer cells, potentially leading to fewer side effects compared to conventional therapies. This study builds on our previous success in identifying TOPK inhibitors and aims to optimize them for improved potency. Methods: An integrated approach combining computational modeling and organic synthesis was employed. Ninety-two analogs of the lead compound (N2 ,N7 -dibenzyl-9-oxo-9H-fluorene-2,7-disulfonamide) were designed virtually and assessed for binding affinity to TOPK using docking simulations. Eight top-scoring analogs were synthesized and their inhibitory activity against TOPK was evaluated in vitro. Results: The in-silico analysis identified eight promising analogs. However, the most active synthesized analog (compound 10) exhibited moderate inhibitory activity (IC50 = 86 µM) compared to the lead compound (IC50 = 54 µM). Conclusion: While the computational approach identified potential candidates, further optimization of the synthetic analogs is necessary to achieve superior TOPK inhibitory activity. This study highlights the value of a combined computational and synthetic strategy for TOPK inhibitor development. TOPK inhibitory activity. This study highlights the value of a combined computational and synthetic strategy for TOPK inhibitor development.

The TOPK Inhibitor HI-TOPK-032 Enhances CAR T-cell Therapy of Hepatocellular Carcinoma by Upregulating Memory T Cells.

Chimeric antigen receptor (CAR) T cells are emerging as an effective antitumoral therapy. However, their therapeutic effects on solid tumors are limited because of their short survival time and the immunosuppressive tumor microenvironment. Memory T cells respond more vigorously and persist longer than their naïve/effector counterparts. Therefore, promoting CAR T-cell development into memory T cells could further enhance their antitumoral effects. HI-TOPK-032 is a T-LAK cell-originated protein kinase (TOPK)-specific inhibitor that moderately represses some types of tumors. However, it is unknown whether HI-TOPK-032 works on hepatocellular carcinoma (HCC) and whether it impacts antitumoral immunity. Using both subcutaneous and orthotopic xenograft tumor models of two human HCC cell lines, Huh-7 and HepG2, we found that HI-TOPK-032 significantly improved proliferation/persistence of CD8+ CAR T cells, as evidenced by an increase in CAR T-cell counts or frequency of Ki-67+CD8+ cells and a decrease in PD-1+LAG-3+TIM-3+CD8+ CAR T cells in vivo. Although HI-TOPK-032 did not significantly suppress HCC growth, it enhanced the capacity of CAR T cells to inhibit tumor growth. Moreover, HI-TOPK-032 augmented central memory CD8+ T cell (TCM) frequency while increasing eomesodermin expression in CD8+ CAR T cells in tumor-bearing mice. Moreover, it augmented CD8+ CAR TCM cells in vitro and reduced their expression of immune checkpoint molecules. Finally, HI-TOPK-032 inhibited mTOR activation in CAR T cells in vitro and in tumors, whereas overactivation of mTOR reversed the effects of HI-TOPK-032 on CD8+ TCM cells and tumor growth. Thus, our studies have revealed mechanisms underlying the antitumoral effects of HI-TOPK-032 while advancing CAR T-cell immunotherapy.

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.

Orobol, 3′-hydroxy-genistein, suppresses the development and regrowth of cutaneous SCC

Chronic solar ultraviolet exposure is a major risk factor for cutaneous squamous cell carcinoma (cSCC), which is the second most common type of skin cancer. Our previous data showed that total protein and phosphorylation levels of T-LAK cell-originated protein kinase (TOPK) were enhanced in solar-simulated light (SSL)-induced skin carcinogenesis and overexpressed in actinic keratosis (AK) and cSCC human skin tissues compared to those in matched normal skin. Thus, targeting TOPK activity could be a helpful approach for treating cSCC. Our data showed that orobol directly binds to TOPK in an ATP-independent manner and inhibits TOPK kinase activity. Furthermore, orobol inhibited anchorage-independent colony formation by SCC12 cells in a dose-dependent manner. After discontinuing the treatment, patients commonly return to tumor-bearing conditions; therefore, therapy or intermittent dosing of drugs must be continued indefinitely. Thus, to examine the efficacy of orobol against the development and regrowth of cSCC, we established mouse models including prevention, and therapeutic models on the chronic SSL-irradiated SKH-1 hairless mice. Early treatment with orobol attenuates chronic SSL-induced cSCC development. Furthermore, orobol showed therapeutic efficacy after the formation of chronic SSL irradiation-induced tumor. In the mouse model with intermittent dosing of orobol, our data showed that re-application of orobol is effective for reducing tumor regrowth after discontinuation of treatment. Moreover, oncogenic protein levels were significantly attenuated by orobol treatment in the SSL-stimulated human skin. Thus, we suggest that orobol, as a promising TOPK inhibitor, could have an effective clinical approach to prevent and treat the development and regrowth of cSCC.

Abstract 407: OTS964, a TOPK inhibitor, is susceptible to ABCG2-mediated drug resistance

Abstract The overexpression of ATP-binding cassette (ABC) transporters has known to be one of the most important mechanisms responsible for the development of multidrug resistance (MDR). OTS964 is a potent T-LAK cell-originated protein kinase (TOPK) inhibitor. Herein, we investigated the interaction of OTS964 and MDR-associated ATP-binding cassette sub-family G member 2 (ABCG2, breast cancer resistance protein/BCRP). The cell viability assay indicated that the effectiveness of OTS964 is limited in drug-resistant and gene-transfected cells overexpressing ABCG2. We found that the known ABCG2 inhibitor is able 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 and mRNA expression levels, resulting in enhanced resistance to ABCG2 substrate-drugs. The ATPase assay demonstrated that OTS964 stimulates ATPase activity of ABCG2 in a concentration-dependent manner, and that this stimulation can be antagonized by a verified ABCG2 ATPase inhibitor. Additionally, the computational molecular docking analysis combined with results from ATPase assay suggested that OTS964 interacts with drug-binding pocket of ABCG2 protein 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. Citation Format: Yuqi Yang, Zhuo-Xun Wu, Jing-Quan Wang, Qiu-Xu Teng, Zi-Ning Lei, Sabrina Lusvarghi, Suresh V. Ambudkar, Ning Ji, Zhe-Sheng Chen. OTS964, a TOPK inhibitor, is susceptible to ABCG2-mediated drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 407.

PBK/TOPK Inhibitor Suppresses the Progression of Prolactinomas.

BackgroundProlactinoma is the most common type of pituitary tumors, and its resultant tumor occupying and hormone disturbance greatly damage the health of patients. In this study, we investigated a protein kinase-PDZ Binding Kinase (PBK)/T-LAK Cell-Originated Protein Kinase (TOPK) as a candidate protein regulating prolactin (PRL) secretion and tumor growth of prolactinomas.MethodsDownloaded prolactinoma transcriptome dataset from Gene Expression Omnibus (GEO) database, and screened differentially expressed genes (DEGs) between normal pituitary tissues and prolactinoma tissues. Then, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs were performed, a protein-protein interaction (PPI) network was constructed and the hub genes were identified. After a literature search, TOPK was presumed as an candidate target regulating the prolactinoma. We found a specific inhibitor of TOPK to investigate its effects on the proliferation, migration, apoptosis and PRL secretion of pituitary tumor cells. Finally, the regulation of TOPK inhibitor on its downstream target-p38 Mitogen Activated Protein Kinase (p38 MAPK) was detected to explore the potential mechanism.ResultsA total of 361 DEGs were identified, and 20 hub genes were screened out. TOPK inhibitor HI-TOPK-032 could suppress the proliferation & migration and induce apoptosis of pituitary tumor cells in vitro, and reduce PRL secretion and tumor growth in vivo. HI-TOPK-032 also inhibited the phosphorylation level of the downstream target p38 MAPK, suggesting that TOPK inhibitors regulate the development of prolactinoma by mediating p38 MAPK.ConclusionOur study of identification and functional validation of TOPK suggests that this candidate can be a promising molecular target for prolactinoma 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.

Abstract 6380: Suppression of the solar ultraviolet-induced skin carcinogenesis by TOPK inhibitor HI-TOPK-032

Abstract Non-melanoma skin cancer (NMSC) such as cutaneous squamous cell carcinoma (cSCC) is caused by solar ultraviolet (SUV) exposure and is the most common cancer in the United States. T-LAK cell-originated protein kinase (TOPK), a serine-threonine kinase is activated by SUV irradiation and involved in skin carcinogenesis. Strategies with research focusing on the TOPK signaling pathway and targeted therapy in skin carcinogenesis may helpful for the discovery of additional treatments against skin cancer. In this study, we found that TOPK can directly bind to and phosphorylate c-Jun (as one of the core member of AP-1) at Ser63 and Ser73 after SSL exposure in a JNKs-independent manner. TOPK knocking down, or HI-TOPK-032 (TOPK specific inhibitor) attenuated colony formation and cell proliferation of skin cancer cells. Phosphorylated levels of c-Jun were overexpressed in human AK and cSCC compared to normal skin tissues, and HI-TOPK-032 inhibited the phosphorylation of c-Jun in SCC cell line in a dose-dependent manner. Furthermore, HI-TOPK-032 decreased SSL-induced AP-1 transactivation activity. Moreover, acute SSL-induced inflammation was attenuated by the topical application of HI-TOPK-032 in SKH1 hairless mice. Importantly, HI-TOPK-032 suppressed chronic SSL-induced skin carcinogenesis and c-Jun phosphorylation levels in SKH1 hairless mice. Our results demonstrate that TOPK can phosphorylate and activate c-Jun at Ser63 and Ser73 in the process of skin carcinogenesis and HI-TOPK-032 could be used as a potential chemopreventive drug against cSCC development. Citation Format: Eunmiri Roh, Yaping Han, Kanamata Reddy, Tatyana A. Zykova, Mee Hyun Lee, Ke Yao, Ruihua Bai, Clara Curiel-Lewandrowski, Zigang Dong. Suppression of the solar ultraviolet-induced skin carcinogenesis by TOPK inhibitor HI-TOPK-032 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6380.

Suppression of the solar ultraviolet-induced skin carcinogenesis by TOPK inhibitor HI-TOPK-032.

Nonmelanoma skin cancer (NMSC) such as cutaneous squamous cell carcinoma (cSCC) is caused by solar ultraviolet (SUV) exposure and is the most common cancer in the United States. T-LAK cell-originated protein kinase (TOPK), a serine-threonine kinase is activated by SUV irradiation and involved in skin carcinogenesis. Strategies with research focusing on the TOPK signaling pathway and targeted therapy in skin carcinogenesis may helpful for the discovery of additional treatments against skin cancer. In this study, we found that TOPK can directly bind to and phosphorylate c-Jun (as one of the core member of AP-1) at Ser63 and Ser73 after SSL exposure in a JNKs-independent manner. TOPK knocking down, or HI-TOPK-032 (TOPK specific inhibitor) attenuated colony formation and cell proliferation of skin cancer cells. Phosphorylated levels of c-Jun were overexpressed in human AK and cSCC compared with normal skin tissues, and HI-TOPK-032 inhibited the phosphorylation of c-Jun in SCC cell line in a dose-dependent manner. Furthermore, HI-TOPK-032 decreased SSL-induced AP-1 transactivation activity. Moreover, acute SSL-induced inflammation was attenuated by the topical application of HI-TOPK-032 in SKH1 hairless mice. Importantly, HI-TOPK-032 suppressed chronic SSL-induced skin carcinogenesis and c-Jun phosphorylation levels in SKH1 hairless mice. Our results demonstrate that TOPK can phosphorylate and activate c-Jun at Ser63 and Ser73 in the process of skin carcinogenesis and HI-TOPK-032 could be used as a potential chemopreventive drug against cSCC development.

TOPK promotes metastasis of esophageal squamous cell carcinoma by activating the Src/GSK3\u03b2/STAT3 signaling pathway via \u03b3-catenin

BackgroundEsophageal 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.MethodsTissue 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.ResultsThe 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.ConclusionThe 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.

Eupafolin Suppresses Esophagus Cancer Growth by Targeting T-LAK Cell-Originated Protein Kinase

Eupafolin is the main bioactive component extracted from the traditional Chinese medicine Ay Tsao (Artemisia vulgaris L.), and its anti-tumor activity has had been studied in previous researches. T-LAK cell-originated protein kinase (TOPK) belongs to serine/threonine protein kinase and is highly expressed in several cancer cells and tissues, such as colon cancer, lung cancer, esophagus cancer, and so on. Therefore, it was recognized as an important target for treating tumors. Nowadays, we found that eupafolin suppressed TOPK activities at the first time in vitro and in vivo. The cells study indicated that eupafolin suppressed TOPK activities in JB6 Cl41 and KYSE450 cells. Furthermore, knockdown of TOPK in KYSE450 cells decreased their sensitivities to eupafolin. The animal study showed that the injection of eupafolin in patient-derived xenograft (PDX) mouse effectively suppressed tumor growth. Histone H3 and Ki67 were reduced, and cleaved caspase 3 was increased in tumor tissues after eupafolin treatment. To sum up, eupafolin as an TOPK inhibitor can suppress growth of esophagus cancer in vitro and in vivo. The TOPK downstream signaling molecule histone H3 in tumor tissues was also reduced after eupafolin treatment. In short, eupafolin can suppress growth of esophagus cancer cells as an TOPK inhibitor both in vitro and in vivo.

Abstract 2373: ADA-07 suppresses solar ultraviolet-induced skin carcinogenesis by directly inhibiting TOPK

Abstract Cumulative exposure to solar ultraviolet (SUV) irradiation is regarded as the major etiologic factor in the development of skin cancer. The activation of the mitogen-activated protein kinase (MAPK) cascades occurs rapidly and is vital in the regulation of SUV-induced cellular responses. The T-LAK cell-originated protein kinase (TOPK), an upstream activator of MAPKs, is heavily involved in inflammation, DNA damage, and tumor development. However, the chemopreventive and therapeutic effects of specific TOPK inhibitors in SUV-induced skin cancer have not yet been elucidated. In the current study, ADA-07, a novel TOPK inhibitor, was synthesized and characterized. Pull-down assay results, ATP competition and in vitro kinase assay data revealed that ADA-07 interacted with TOPK at the ATP-binding pocket and inhibited its kinase activity. Western blot analysis showed that ADA-07 suppressed SUV-induced phosphorylation of ERK1/2, p38, and JNKs, and subsequently inhibited AP-1 activity. Importantly, topical treatment with ADA-07 dramatically attenuated tumor incidence, multiplicity, and volume in SKH-1 hairless mice exposed to chronic SUV. Our findings suggest that ADA-07 is a promising chemopreventive or potential therapeutic agent against SUV-induced skin carcinogenesis that acts by specifically targeting TOPK. Citation Format: Tianshun Zhang, Qiushi Wang, Ge Gao, Bode Ann, Zigang Dong. ADA-07 suppresses solar ultraviolet-induced skin carcinogenesis by directly inhibiting TOPK [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2373.

ADA-07 Suppresses Solar Ultraviolet-Induced Skin Carcinogenesis by Directly Inhibiting TOPK.

Cumulative exposure to solar ultraviolet (SUV) irradiation is regarded as the major etiologic factor in the development of skin cancer. The activation of the MAPK cascades occurs rapidly and is vital in the regulation of SUV-induced cellular responses. The T-LAK cell-originated protein kinase (TOPK), an upstream activator of MAPKs, is heavily involved in inflammation, DNA damage, and tumor development. However, the chemopreventive and therapeutic effects of specific TOPK inhibitors in SUV-induced skin cancer have not yet been elucidated. In the current study, ADA-07, a novel TOPK inhibitor, was synthesized and characterized. Pull-down assay results, ATP competition, and in vitro kinase assay data revealed that ADA-07 interacted with TOPK at the ATP-binding pocket and inhibited its kinase activity. Western blot analysis showed that ADA-07 suppressed SUV-induced phosphorylation of ERK1/2, p38, and JNKs and subsequently inhibited AP-1 activity. Importantly, topical treatment with ADA-07 dramatically attenuated tumor incidence, multiplicity, and volume in SKH-1 hairless mice exposed to chronic SUV. Our findings suggest that ADA-07 is a promising chemopreventive or potential therapeutic agent against SUV-induced skin carcinogenesis that acts by specifically targeting TOPK. Mol Cancer Ther; 16(9); 1843-54. ©2017 AACR.

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 (IC 50; 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.

T-LAK Cell-Originated Protein Kinase (TOPK) as a Prognostic Factor and a Potential Therapeutic Target in Ovarian Cancer.

We aimed to clarify the clinical significance of TOPK (T-lymphokine-activated killer cell-originated protein kinase) expression in ovarian cancer and evaluate the possible effect of TOPK inhibitors, OTS514 and OTS964, on ovarian cancer cells. TOPK expression was examined by immunohistochemistry using 163 samples with epithelial ovarian cancer (EOC). TOPK protein level and FOXM1 transcriptional level in ovarian cancer cell lines were examined by Western blot and RT-PCR, respectively. Half-maximum inhibitory concentration (IC50) values against TOPK inhibitors were examined by the MTT assay. Using the peritoneal dissemination model of ES-2 ovarian cancer cells, we examined the in vivo efficacy of OTS514. In addition, the cytotoxic effect of OTS514 and OTS964 on 31 patient-derived primary ovarian cancer cells was examined. TOPK was expressed very highly in 84 (52%) of 163 EOC tissues, and high TOPK expression was significantly associated with poor progression-free survival and overall survival in early-stage cases of EOC (P = 0.008 and 0.006, respectively). Both OTS514 and OTS964 showed significant growth-inhibitory effect on ovarian cancer cell lines with IC50 values of 3.0 to 46 nmol/L and 14 to 110 nmol/L, respectively. TOPK protein and transcriptional levels of FOXM1 were reduced by TOPK inhibitor treatment. Oral administration of OTS514 significantly elongated overall survival in the ES-2 abdominal dissemination xenograft model, compared with vehicle control (P < 0.001). Two drugs showed strong growth-inhibitory effect on primary ovarian cancer cells regardless of tumor sites or histological subtypes. Our results demonstrated the clinical significance of high TOPK expression and potential of TOPK inhibitors to treat ovarian cancer. Clin Cancer Res; 22(24); 6110-7. ©2016 AACR.

Remote ischemic postconditioning protects against renal ischemia/reperfusion injury by activation of T-LAK-cell-originated protein kinase (TOPK)/PTEN/Akt signaling pathway mediated anti-oxidation and anti-inflammation

BackgroundRecent clinical and animal studies suggested that remote limb ischemic postconditioning (RIPostC) can invoke potent cardioprotection or neuroprotection. However, the effect and mechanism of RIPostC against renal ischemia/reperfusion injury (IRI) are poorly understood. T-LAK-cell-originated protein kinase (TOPK) is crucial for the proliferation and migration of tumor cells. However, the function of TOPK and the molecular mechanism underlying renal protection remain unknown. Therefore, this study aimed to evaluate the role of TOPK in renoprotection induced by RIPostC. Materials and MethodsThe renal IRI model was induced by left renal pedicle clamping for 45min followed by 24h reperfusion and right nephrectomy. All mice were intraperitoneally injected with vehicle, TOPK inhibitor HI-TOPK-032 or Akt inhibitor LY294002. After 24h reperfusion, renal histology, function, and inflammatory cytokines and oxidative stress were assessed. The proteins were measured by Western blotting. ResultsThe results showed that RIPostC significantly protected the kidneys against IRI. The protective effects were accompanied by the attenuation of renal dysfunction, tubular damage, inflammation and oxidative stress. In addition, RIPostC increased the phosphorylation of TOPK, PTEN, Akt, GSK3β and the nuclear translocation of Nrf2 and decreased the nuclear translocation of NF-κB. However, all of the above renoprotective effects of RIPostC were eliminated either by the inhibition of TOPK or Akt with HI-TOPK-032 or LY294002. ConclusionsThe current data reveal that RIPostC protects against renal IRI via activation of TOPK/PTEN/Akt signaling pathway mediated anti-oxidation and anti-inflammation.

T-LAK cell-originated protein kinase presents a novel therapeutic target in FLT3-ITD mutated acute myeloid leukemia.

Gain-of-function mutations of FLT3 (FLT3-ITD), comprises up to 30% of normal karyotype acute myeloid leukemia (AML) and is associated with an adverse prognosis. Current FLT3 kinase inhibitors have been tested extensively, but have not yet resulted in a survival benefit and novel therapies are awaited. Here we show that T-LAK cell-originated protein kinase (TOPK), a mitotic kinase highly expressed in and correlated with more aggressive phenotype in several types of cancer, is expressed in AML but not in normal CD34+ cells and that TOPK knockdown decreased cell viability and induced apoptosis. Treatment of AML cells with TOPK inhibitor (OTS514) resulted in a dose-dependent decrease in cell viability with lower IC50 in FLT3-mutated cells, including blasts obtained from patients relapsed after FLT3-inhibitor treatment. Using a MV4-11-engrafted mouse model, we found that mice treated with 7.5 mg/kg IV daily for 3 weeks survived significantly longer than vehicle treated mice (median survival 46 vs 29 days, P < 0.001). Importantly, we identified TOPK as a FLT3-ITD and CEBPA regulated kinase, and that modulating TOPK expression or activity resulted in significant decrease of FLT3 expression and CEBPA phosphorylation. Thus, targeting TOPK in FLT3-ITD AML represents a novel therapeutic approach for this adverse risk subset of AML.

Abstract 4381: High efficacy of T-LAK cell-originated protein kinase inhibitor in acute myeloid leukemia with FLT3-ITD mutation

Abstract The internal tandem duplication (FLT3-ITD) a gain-of-function mutation of FLT3, is associated with poor outcome in acute myeloid leukemia (AML). The use of FLT3 inhibitors currently undergoing clinical investigation has not yet improved overall survival. Therefore, novel therapies are needed. T-LAK cell-originated protein kinase (TOPK), a serine-threonine protein kinase, is highly expressed and associated with an aggressive cancer phenotype, but is hardly detectable in normal tissues. Here, we investigate TOPK in AML and demonstrate that it is highly expressed in most AML cell lines and some primary blasts, but is not detected in CD34+ cells of healthy donors. MV4-11 and U937 cells transfected with TOPK-siRNA showed significant decrease in cell viability (∼70%, P&amp;lt;0.001). We then examined the anti-leukemia activity of TOPK inhibitor OTS514 in AML. Primary blasts obtained from 3 patients (pts) with AML showed significant decrease in cell viability in a dose-dependent manner (IC50 values were 10-20nM). Moreover, OTS514 treatment resulted in significant decrease in number of colonies of CD34+ cells obtained from a pt with AML (41 vs 73, P = 0.01), but not of CD34+ cells obtained from healthy donors (39 vs 36, P = 0.67). Treatment of 10 AML cell lines with OTS514 showed that FLT3 mutated cell lines were significantly more sensitive (IC5020nM). Annexin/PI staining showed 80% and 70% increase in apoptosis in FLT3-ITDmut cells (MV4-11 and MOLM13) treated with OTS514 (40nM; 48hrs). In contrast, only 40% and 10% apoptosis was observed in FLT3wt cells (U937 and KG1, respectively) treated under the same conditions. Additionally, cell cycle analysis in cells treated with OTS514 (20nM; 24 and 48 hrs) showed a dramatic decrease of S phase (∼98%; P = 0.003) in MV4-11 but only 70% (P&amp;lt;0.001) and 30% (P = 0.02) in THP-1 (FLT3wt) cells compared with untreated cells. Importantly, OTS514 treatment decreased cell viability and increased cell differentiation and apoptosis in primary blasts from pts relapsed after FLT3 inhibitor treatment (AC220). Furthermore, using a MV4-11-engrafted mouse model, we found that mice treated with 7.5mg/kg IV every day for 3 weeks survived significantly longer than vehicle treated mice (median survival 46 vs 29, P&amp;lt;0.001). Mechanistically, OTS514 or TOPK-siRNA significantly decreased FLT3 mRNA and protein levels and decreased CEBPA phosphorylation in FLT3-ITDmut cells. Furthermore, activating FLT3 in THP-1 cells via FLT3 ligand increased TOPK protein. Also, FLT3 knockdown or inhibition with MLN518 (50 and 100nM) decreased TOPK levels in MV4-11 and MOLM13 cells, but not in U937 cells, suggesting that TOPK is a downstream target of FLT3. In conclusion, TOPK inhibitor exhibits preferential activity in FLT3-ITDmut AML, partially via inhibition of FLT3 expression. Thus, OTS514 represents new targeted therapy for this adverse risk subset of AML. Citation Format: Houda Alachkar, Martin Mutonga, Jae-Hyun Park, Gregory Malnassy, Alex Woods, Gordana Raca, Olatoyosi M. Odenike, Naofumi Takamatsu, Takashi Miyamoto, Shoji Hisada, Yo Matsuo, Wendy Stock, Yusuke Nakamura. High efficacy of T-LAK cell-originated protein kinase inhibitor in acute myeloid leukemia with FLT3-ITD mutation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4381. doi:10.1158/1538-7445.AM2015-4381

Growth Inhibitory Function Of a Novel T-LAK Cell-Originated Protein Kinase Inhibitor On FLT3-ITD Positive Acute Myeloid Leukemia (AML) Cells

Abstract T-LAK cell-originated protein kinase (TOPK/PBK), a serine-threonine mitogen-activated protein kinase kinase is highly expressed and correlated with more aggressive disease in several types of cancer, but is undetectable in normal tissues except the testis and fetal tissues. TOPK is up-regulated in a variety of hematologic malignancies including acute myeloid leukemia (AML) and may be involved in disease pathogenesis. To investigate the role of TOPK in AML and to develop the rationale for therapeutic targeting, we initially examined the expression level of TOPK protein in AML cell lines by western blot analysis. TOPK expression was detected at high levels in 8 out of 11 AML cell lines. Importantly, TOPK was not detected in mobilized, peripheral blood-derived stem cells from healthy donors. To determine the role of TOPK in AML, we utilized a loss of function approach in two AML cell lines (MV4-11 and U937 cells) and assessed cell viability and apoptosis by MTS and Annexin/PI staining assays, respectively. Cells transfected with TOPK-siRNA showed significant decrease in cell viability (∼70%, P&lt;0.001, both cell lines) and significant increase in apoptosis 48 hours following transfection compared to cells transfected with control-siRNA. A small molecule compound that inhibits TOPK kinase is currently undergoing pharmaceutical development for cancer treatment. We treated nine AML cell lines with the compound for 48 hours and assessed cells viability by MTS assay. Decrease in cell viability following treatment with increasing doses of the compound was noted with variable sensitivities among AML cell lines. In addition, the compound showed enhancement of cell differentiation assessed by CD11b staining in U937 cells. Cell lines with FLT3 mutations (MV4-11, MOLM13 and KOCL-48) were significantly more sensitive to the treatment compared to cell lines with unmutated FLT3. We next treated cells with increasing doses of the compound and assessed cells viability and apoptosis by MTS and flow cytometry assays. Following the treatment with the compound, IC50 was &lt;10nM for MV4-11 and MOLM13 cells (FLT3-ITD positive cell lines), and &gt;20nM for U937 and KG1 (FLT3-ITD negative cell lines). 40 nM of the compound induced apoptosis by ∼80% in MV4-11 and MOLM13 cells compared to 49% in U937 and 9% in KG1 cells, at 48 hours following treatment. We also validated the anti-leukemia activity in primary blasts from patients with AML (n=2). FLT3-ITD positive blasts had an IC50 of ∼15nM and showed 40% increase in apoptosis following treatment with 20nM of the compound. To gain a mechanistic insight into why FLT3-ITD mutant cells are preferentially sensitive to this TOPK inhibitor, we performed a gene expression profile microarray analysis on MV4-11 cells treated with 20nM of the compound or transfected with TOPK siRNA in comparison with untreated cells and cells transfected with control-siRNA. We observed significant downregulation in genes involved in cell cycle control pathways in the signatures associated with the compound-treated and TOPK siRNA-transfected cells. Interestingly, FLT3 was among the significantly downregulated genes in the compound treated cells (∼80%) and in TOPK-siRNA transfected cells (∼30%). We then examined the activity and the expression levels of FLT3 protein following the treatment. Consistently, we found that both the phospho-FLT3 and the total FLT3 protein levels were completely depleted in cells treated with 10, 20 and 40 nM of the compound as early as 16 hours following treatment. In conclusion, TOPK is highly expressed in AML and may act as novel therapeutic target. A novel TOPK kinase inhibitor exhibits preferential cytotoxicity to FLT3-ITD mutated AML cells, possibly through inhibition of FLT3 protein expression. Although further research is needed to determine the mechanism by which the compound inhibits FLT3 protein expression, this novel compound may represent a new targeted therapy for this adverse risk subset of patients with AML. Disclosures: Matsuo: OncoTherapy Science, Inc.: Employment. Nakamura:Oncotherapy Science. Ltd.: share holder Other.