Search

Echovirus 30 (E30), a member of the species B Enterovirus family, is a primary pathogen responsible for aseptic meningitis and encephalitis. E30 is associated with severe nervous system diseases and is a primary cause of child illness, disability, and even mortality. However, the mechanisms underlying E30-induced brain injury remain poorly understood. In this study, we used a neonatal mouse model of E30 to investigate the possible mechanisms of brain injury. E30 infection triggered the activation of microglia in the mouse brain and efficiently replicated within HMC3 cells. Subsequent transcriptomic analysis revealed inflammatory activation of microglia in response to E30 infection. We also detected a significant upregulation of polo-like kinase 1 (PLK1) and found that its inhibition could limit E30 infection in a sucking mouse model. Collectively, E30 infection led to brain injury in a neonatal mouse model, which may be related to excessive inflammatory responses. Our findings highlight the intricate interplay between E30 infection and neurological damage, providing crucial insights that could guide the development of interventions and strategies to address the severe clinical manifestations associated with this pathogen. [ABSTRACT FROM AUTHOR]

This review aims to outline mitotic kinase inhibitors' roles as potential therapeutic targets and assess their suitability as a stand-alone clinical therapy or in combination with standard treatments for advanced-stage solid tumors, including triple-negative breast cancer (TNBC). Breast cancer poses a significant global health risk, with TNBC standing out as the most aggressive subtype. Comprehending the role of mitosis is crucial for understanding how TNBC advances from a solid tumor to metastasis. Chemotherapy is the primary treatment used to treat TNBC. Some types of chemotherapeutic agents target cells in mitosis, thus highlighting the need to comprehend the molecular mechanisms governing mitosis in cancer. This understanding is essential for devising targeted therapies to disrupt these mitotic processes, prevent or treat metastasis, and improve patient outcomes. Mitotic kinases like Aurora kinase A, Aurora Kinase B, never in mitosis gene A-related kinase 2, Threonine-Tyrosine kinase, and Polo-kinase 1 significantly impact cell cycle progression by contributing to chromosome separation and centrosome homeostasis. When these kinases go awry, they can trigger chromosome instability, increase cell proliferation, and activate different molecular pathways that culminate in a transition from epithelial to mesenchymal cells. Ongoing clinical trials investigate various mitotic kinase inhibitors as potential biological treatments against advanced solid tumors. While clinical trials against mitotic kinases have shown some promise in the clinic, more investigation is necessary, since they induce severe adverse effects, particularly affecting the hematopoietic system. [ABSTRACT FROM AUTHOR]

Background: Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays an important role in diverse cellular processes by regulating Rho guanosine triphosphate (GTP)ases activity. RhoGDI1 phosphorylation regulates the spatiotemporal activation of Rho GTPases during cell migration. In this study, we identified polo-like kinase 1 (PLK1) as a novel kinase of RhoGDI1 and investigated the molecular mechanism by which the interaction between RhoGDI1 and PLK1 regulates cancer cell migration. Methods: Immunoprecipitation, GST pull-down assay, and proximity ligation assay (PLA) were performed to analyze the interaction between RhoGDI1 and PLK1. In vitro kinase assay and immunoprecipitation were performed with Phospho-(Ser/Thr) antibody. We evaluated RhoA activation using RhoGTPases activity assay. Cell migration and invasion were analyzed by transwell assays. Results: GST pull-down assays and PLA showed that PLK1 directly interacted with RhoGDI1 in vitro and in vivo. Truncation mutagenesis revealed that aa 90-111 of RhoGDI1 are critical for interacting with PLK1. We also showed that PLK1 phosphorylated RhoGDI1 at Thr7 and Thr91, which induces cell motility. Overexpression of the GFP-tagged RhoGDI1 truncated mutant (aa 90-111) inhibited the interaction of PLK1 with RhoGDI1 and attenuated RhoA activation by PLK1. Furthermore, the overexpression of the RhoGDI1 truncated mutant reduced cancer cell migration and invasion in vitro and suppressed lung metastasis in vivo. Conclusions: Collectively, we demonstrate that the phosphorylation of RhoGDI1 by PLK1 promotes cancer cell migration and invasion through RhoA activation. This study connects the interaction between PLK1 and RhoGDI1 to the promotion of cancer cell behavior associated with malignant progression, thereby providing opportunities for cancer therapeutic interventions. [ABSTRACT FROM AUTHOR]

Background: KRASG12C inhibitors (KRASG12Ci) AMG510 and MRTX849 have shown promising efficacy in clinical trials and been approved for the treatment of KRASG12C-mutant cancers. However, the emergence of therapy-related drug resistance limits their long-term potential. This study aimed to identify the critical mediators and develop overcoming strategies. Methods: By using RNA sequencing, RT-qPCR and immunoblotting, we identified and validated the upregulation of c-Myc activity and the amplification of the long noncoding RNA ST8SIA6-AS1 in KRASG12Ci-resistant cells. The regulatory axis ST8SIA6-AS1/Polo-like kinase 1 (PLK1)/c-Myc was investigated by bioinformatics, RNA fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and chromatin immunoprecipitation. Gain/loss-of-function assays, cell viability assay, xenograft models, and IHC staining were conducted to evaluate the anti-cancer effects of co-inhibition of ST8SIA6-AS1/PLK1 pathway and KRAS both in vitro and in vivo. Results: KRASG12Ci sustainably decreased c-Myc levels in responsive cell lines but not in cell lines with intrinsic or acquired resistance to KRASG12Ci. PLK1 activation contributed to this ERK-independent c-Myc stability, which in turn directly induced PLK1 transcription, forming a positive feedback loop and conferring resistance to KRASG12Ci. ST8SIA6-AS1 was found significantly upregulated in resistant cells and facilitated the proliferation of KRASG12C-mutant cancers. ST8SIA6-AS1 bound to Aurora kinase A (Aurora A)/PLK1 and promoted Aurora A-mediated PLK1 phosphorylation. Concurrent targeting of KRAS and ST8SIA6-AS1/PLK1 signaling suppressed both ERK-dependent and -independent c-Myc expression, synergistically led to cell death and tumor regression and overcame KRASG12Ci resistance. Conclusions: Our study deciphers that the axis of ST8SIA6-AS1/PLK1/c-Myc confers both intrinsic and acquired resistance to KRASG12Ci and represents a promising therapeutic target for combination strategies with KRASG12Ci in the treatment of KRASG12C-mutant cancers. [ABSTRACT FROM AUTHOR]

Background: More than 90% of the mortality of triple-negative breast cancer (TNBC) patients is attributed to cancer metastasis with organotropism. The lung is a frequent site of TNBC metastasis. However, the precise molecular mechanism for lung-specific metastasis of TNBC is not well understood. Methods: RNA sequencing was performed to identify patterns of gene expression associated with lung metastatic behavior using 4T1-LM3, MBA-MB-231-LM3, and their parental cells (4T1-P, MBA-MB-231-P). Expressions of RGCC, called regulator of cell cycle or response gene to complement 32 protein, were detected in TNBC cells and tissues by qRT-PCR, western blotting, and immunohistochemistry. Kinase activity assay was performed to evaluate PLK1 kinase activity. The amount of phosphorylated AMP-activated protein kinase α2 (AMPKα2) was detected by immunoblotting. RGCC-mediated metabolism was determined by UHPLC system. Oxidative phosphorylation was evaluated by JC-1 staining and oxygen consumption rate (OCR) assay. Fatty acid oxidation assay was conducted to measure the status of RGCC-mediated fatty acid oxidation. NADPH and ROS levels were detected by well-established assays. The chemical sensitivity of cells was evaluated by CCK8 assay. Results: RGCC is aberrantly upregulated in pulmonary metastatic cells. High level of RGCC is significantly related with lung metastasis in comparison with other organ metastases. RGCC can effectively promote kinase activity of PLK1, and the activated PLK1 phosphorylates AMPKα2 to facilitate TNBC lung metastasis. Mechanistically, the RGCC/PLK1/AMPKα2 signal axis increases oxidative phosphorylation of mitochondria to generate more energy, and promotes fatty acid oxidation to produce abundant NADPH. These metabolic changes contribute to sustaining redox homeostasis and preventing excessive accumulation of potentially detrimental ROS in metastatic tumor cells, thereby supporting TNBC cell survival and colonization during metastases. Importantly, targeting RGCC in combination with paclitaxel/carboplatin effectively suppresses pulmonary TNBC lung metastasis in a mouse model. Conclusions: RGCC overexpression is significantly associated with lung-specific metastasis of TNBC. RGCC activates AMPKα2 and downstream signaling through RGCC-driven PLK1 activity to facilitate TNBC lung metastasis. The study provides implications for RGCC-driven OXPHOS and fatty acid oxidation as important therapeutic targets for TNBC treatment. [ABSTRACT FROM AUTHOR]

Background: Understanding the mechanism behind immune cell plasticity in cancer metastasis is crucial for identifying key regulators. Previously we found that mitotic factors regulate epithelial-mesenchymal transition, but how these factors convert to metastatic players in the tumor microenvironment (TME) is not fully understood. Methods: The clinical importance of mitotic factors was analyzed by heatmap analysis, a KM plot, and immunohistochemistry in lung adenocarcinoma (LUAD) patients. Immunoprecipitation, LC–MS/MS, kinase assay, and site-directed mutagenesis were performed for the interaction and phosphorylation. A tail-vein injection mouse model, Transwell-based 3D culture, microarray analysis, coculture with monocytes, and chromatin immunoprecipitation assays were used to elucidate the function of phosphorylated FoxM1 in metastasis of TME. Results: The phosphorylated FoxM1 at Ser25 by PLK1 acquires the reprogramming ability to stimulate the invasive traits in cancer and influence immune cell plasticity. This invasive form of p-FoxM1 upregulates the expression of IL1A/1B, VEGFA, and IL6 by direct activation, recruiting monocytes and promoting the polarization of M2d-like tumor-associated macrophages (TAMs). Upregulation of PD-L1 in LUAD having phosphomimetic FoxM1 facilitates immune evasion. In invasive LUAD with phosphomimetic FoxM1, IFITM1 is the most highly expressed through the activation of the STING-TBK1-IRF3 signaling, which enhances FoxM1-mediated signaling. Clinically, higher expression of FOXM1, PLK1, and IFITM1 is inversely correlated with the survival rate of advanced LUAD patients, providing a promising therapeutic strategy for the treatment of LUAD. Conclusion: FoxM1-based therapy would be a potential therapeutic strategy for LUAD to reduce TAM polarization, immune escape, and metastasis, since FoxM1 functions as a genetic reprogramming factor reinforcing LUAD malignancy in the TME. [ABSTRACT FROM AUTHOR]

Background: HeberFERON is a co-formulation of α2b and γ interferons, based on their synergism, which has shown its clinical superiority over individual interferons in basal cell carcinomas. In glioblastoma (GBM), HeberFERON has displayed promising preclinical and clinical results. This led us to design a microarray experiment aimed at identifying the molecular mechanisms involved in the distinctive effect of HeberFERON compared to the individual interferons in U-87MG model. Methods: Transcriptional expression profiling including a control (untreated) and three groups receiving α2b-interferon, γ-interferon and HeberFERON was performed using an Illumina HT-12 microarray platform. Unsupervised methods for gene and sample grouping, identification of differentially expressed genes, functional enrichment and network analysis computational biology methods were applied to identify distinctive transcription patterns of HeberFERON. Validation of most representative genes was performed by qPCR. For the cell cycle analysis of cells treated with HeberFERON for 24 h, 48 and 72 h we used flow cytometry. Results: The three treatments show different behavior based on the gene expression profiles. The enrichment analysis identified several mitotic cell cycle related events, in particular from prometaphase to anaphase, which are exclusively targeted by HeberFERON. The FOXM1 transcription factor network that is involved in several cell cycle phases and is highly expressed in GBMs, is significantly down regulated. Flow cytometry experiments corroborated the action of HeberFERON on the cell cycle in a dose and time dependent manner with a clear cellular arrest as of 24 h post-treatment. Despite the fact that p53 was not down-regulated, several genes involved in its regulatory activity were functionally enriched. Network analysis also revealed a strong relationship of p53 with genes targeted by HeberFERON. We propose a mechanistic model to explain this distinctive action, based on the simultaneous activation of PKR and ATF3, p53 phosphorylation changes, as well as its reduced MDM2 mediated ubiquitination and export from the nucleus to the cytoplasm. PLK1, AURKB, BIRC5 and CCNB1 genes, all regulated by FOXM1, also play central roles in this model. These and other interactions could explain a G2/M arrest and the effect of HeberFERON on the proliferation of U-87MG. Conclusions: We proposed molecular mechanisms underlying the distinctive behavior of HeberFERON compared to the treatments with the individual interferons in U-87MG model, where cell cycle related events were highly relevant. [ABSTRACT FROM AUTHOR]

Background: Intestinal barrier integrity in the pathogenesis of sepsis is critical. Despite an abundance of evidence, the molecular mechanism of the intestinal barrier in sepsis pathology remains unclear. Here, we report a protective role of polo-like kinase 1 (PLK1) in intestinal barrier integrity during sepsis. Methods: Mice with PLK1 overexpression (CAG-PLK1 mice) or PLK1 inhibition (BI2536-treated mice) underwent caecal ligation and puncture (CLP) to establish a sepsis model. The intestinal barrier function, apoptosis in the intestinal epithelium, mitochondrial function and NF-κB signalling activity were evaluated. To suppress the activation of NF-κB signalling, the NF-κB inhibitor PDTC, was administered. The Caco-2 cell line was chosen to establish an intestinal epithelial injury model in vitro. Results: Sepsis destroyed intestinal barrier function, induced excessive apoptosis in the intestinal epithelium, and disrupted the balance of mitochondrial dynamics in wild-type mice. PLK1 overexpression alleviated sepsis-induced damage to the intestinal epithelium by inhibiting the activation of NF-κB signalling. PLK1 colocalized and interacted with TANK in Caco-2 cells. Transfecting Caco-2 cells with TANK-SiRNA suppressed NF-κB signalling and ameliorated mitochondrial dysfunction, apoptosis and the high permeability of cells induced by lipopolysaccharide (LPS). Furthermore, TANK overexpression impaired the protective effect of PLK1 on LPS-induced injuries in Caco-2 cells. Conclusion: Our findings reveal that the PLK1/TANK/NF-κB axis plays a crucial role in sepsis-induced intestinal barrier dysfunction by regulating mitochondrial dynamics and apoptosis in the intestinal epithelium and might be a potential therapeutic target in the clinic. [ABSTRACT FROM AUTHOR]

Background: Decidualization is essential to the successful pregnancy in mice. The molecular mechanisms and effects of Aurora kinase A (Aurora A) remain poorly understood during pregnancy. This study is the first to investigate the expression and role of Aurora A during mouse decidualization. Methods: Quantitative real time polymerase chain reaction, western blotting and in situ hybridization were used to determine the expression of Aurora A in mouse uteri. Aurora A activity was inhibited by Aurora A inhibitor to explore the role of Aurora A on decidualization via regulating the Aurora A/Stat3/Plk1/Cdk1 signaling pathway. Results: Aurora A was strongly expressed at implantation sites compared with inter-implantation sites. Furthermore, Aurora A was also significantly increased in oil-induced deciduoma compared with control. Both Aurora A mRNA and protein were significantly increased under in vitro decidualization. Under in vitro decidualization, Prl8a2, a marker of mouse decidualization, was significantly decreased by TC-S 7010, an Aurora A inhibitor. Additionally, Prl8a2 was reduced by Stat3 inhibitor, Plk1 inhibitor and Cdk1 inhibitor, respectively. Moreover, the protein levels of p-Stat3, p-Plk1 and p-Cdk1 were suppressed by TC-S 7010. The protein levels of p-Stat3, p-Plk1 and p-Cdk1 were also suppressed by S3I-201, a Stat3 inhibitor). SBE 13 HCl (Plk1 inhibitor) could reduce the protein levels of p-Plk1 and p-Cdk1. Collectively, Aurora A could regulate Stat3/Plk1/Cdk1 signaling pathway. Conclusion: Our study shows that Aurora A is expressed in decidual cells and should be important for mouse decidualization. Aurora A/Stat3/Plk1/Cdk1 signaling pathway may be involved in mouse decidualization. [ABSTRACT FROM AUTHOR]

Background: ALDOA is a glycolytic enzyme found mainly in developing embryos, adult muscle and various malignant tumours, including pancreatic tumours. Our previous study revealed that ALDOA, an oncogene, can promote the proliferation and metastasis of pancreatic tumours. Furthermore, ALDOA could predict poor prognosis in patients with pancreatic tumours. Methods: IHC analysis of PDAC tissues was conducted. Western blotting, PCR, cellular IF experiments and cell cycle assessment were conducted utilizing cell lines. GSEA and KEGG pathway analysis were used to identify potential downstream pathways. Results: To explore the effects of ALDOA on the occurrence and development of pancreatic tumours, we analysed the RNA sequencing results and found that ALDOA could inhibit the DDR. Under normal circumstances, when DNA is damaged, initiation of the DDR causes cell cycle arrest, DNA repair or cell apoptosis. Further experiments showed that ALDOA could inhibit DNA repair and reverse cell cycle arrest induced by DNA damage so that DNA damage persisted to promote the occurrence and progression of cancer. Conclusions: Regarding the molecular mechanism, we found that ALDOA inhibited the DDR and improved activation of the cell cycle checkpoint PLK1 by suppressing ATM, which promotes tumour cell progression. Consequently, ALDOA has a profound effect on pancreatic cancer development. [ABSTRACT FROM AUTHOR]

RSF1, remodelling and spacing factor 1, is an important interphase centromere protein and is overexpressed in many types of cancers and correlated with poor overall survival. RSF1 has functions mainly in maintaining chromosome stability, facilitating DNA repair, maintaining the protein homeostasis of RSF1 and suppressing the transcription of some oncogenes when RSF1 protein is expressed at an optimal level; however, RSF1 overexpression facilitates drug resistance and cell cycle checkpoint inhibition to prompt cancer proliferation and survival. The RSF1 expression level and gene background are crucial for RSF1 functions, which may explain why RSF1 has different functions in different cancer types. This review summarizes the functional domains of RSF1, the overexpression status of RSF1 and SNF2H in cancer based on the TCGA and GTEX databases, the cancer-related functions of RSF1 in interacting with H2Aub, HDAC1, CENP-A, PLK1, ATM, CENP-S, SNF2H, HBX, BubR1, cyclin E1, CBP and NF-κB and the potential clinical value of RSF1, which will lay a theoretical foundation for the structural biology study of RSF1 and application of RSF1 inhibitors, truncated RSF1 proteins and SNF2H inhibitors in the treatment of RSF1-overexpressing tumours. [ABSTRACT FROM AUTHOR]

Background: Ovarian cancer (OC) is a life-threatening gynecological malignancy where dysregulation of microRNAs (miRNAs) is frequently implicated. This study focuses on the function of miR-545 on OC development and the molecules involved.Methods: miR-545 expression in OC tissues and cell lines was determined, and its link to the survival of patients was analyzed. Altered expression of miR-545 was induced to determine its role in proliferation, apoptosis, migration and invasion of OC cells and the angiogenesis ability of human umbilical vein endothelial cells (HUVECs). The targeting mRNAs of miR-545 were predicted and validated through luciferase assays. Gain-of-function studies of KDM4B and PLK1 were performed to explore their involvements in OC development. In vivo experiments were conducted by inducing xenograft tumors in nude mice.Results: Poor expression of miR-545 was found in OC tissues and cells compared to the normal ones and it indicated unfavorable prognosis in patients. Overexpression of miR-545 suppressed growth, migration, invasion and angiogenesis of OC cells as well as the angiogenesis ability of HUVECs. miR-545 was found to target mRNAs of KDM4B and PLK1, while KDM4B promoted the transcription of the PLK1 promoter through demethylation of H3K9me3. Either overexpression of KDM4B or PLK1 partially blocked the inhibitory effects of miR-545 mimic on OC cell growth, especially the former one. The in vitro results were reproduced in vivo.Conclusion: This study evidenced that miR-545 suppresses progression of OC through mediating PLK1 expression by a direct binding and an indirect regulation involving KDM4B-mediated demethylation. [ABSTRACT FROM AUTHOR]

Background: The significance of PLK1 (polo-like kinase 1) has become increasingly essential as both a biomarker and a target for cancer treatment. Here, we aimed to determine the downstream genes of PLK1 and their effects on the carcinogenesis and progression of bladder cancer.Methods: Specific siRNA was utilized to silence the target gene expression. The cell proliferation, invasion and migration of bladder cancer cells by MTT assay, BrdU assay and transwell assay. The differential expression genes were identified using Affymetrix HTA2.0 Array. The KEGG, GO and STRING analysis were used to analyze the signaling pathway and protein-protein interaction. Spearman analysis was used to analyze the correlation between protein and protein, between protein and clincopathologic characteristics.Results: PLK1 siRNA hindered the proliferation, invasion and migration of bladder cancer cells, as determined by the MTT, BrdU and transwell assays. A total of 561 differentially expressed genes were identified using an Affymetrix HTA2.0 Array in PLK1 knockdown T24 cells. According to KEGG, GO and STRING analysis, five key genes (BUB1B, CCNB1, CDC25A, FBXO5, NDC80) were determined to be involved in cell proliferation, invasion and migration. PLK1 knockdown decreased BUB1B, CCNB1, CDC25A and NDC80 expressions but increased FBXO5 expression. BUB1B, CCNB1, CDC25A and NDC80 were positively correlated with cell proliferation, invasion, migration and PLK1 expression in tissues, but FBXO5 was negatively correlated with each of those factors. The results showed that the five genes expressions were significantly correlation with the PLK1 expression in normal bladder tissues and bladder cancer tissues. Four of them (BUB1B, CCNB1, CDC25A, NDC80) were obviously positive correlations with pT stage and metastasis. But FBXO5 was negative correlated with pT stage and metastasis. Furthermore, significant correlations were found between CCNB1 or CDC25A or NDC80 and histological grade; between BUB1B or NDC80 and recurrence.Conclusion: Five downstream genes of PLK1 were associated with the regulation of cell proliferation, invasion and migration in bladder cancer. Furthermore, these genes may play important roles in bladder cancer and become important biomarkers and targets for cancer treatment. [ABSTRACT FROM AUTHOR]

Background: Lysine-specific histone demethylase 1 (LSD1) modulates chromatin status through demethylation of H3K4 and H3K9. It has been demonstrated that LSD1 is hyperphosphorylated and dissociates from chromatin during mitosis. However, the molecular mechanism of LSD1 detachment is unknown. Results: In this report, we found that polo-like kinase 1 (PLK1) directly interacted with LSD1 and phosphorylated LSD1 at Ser-126 . Nocodazole-induced metaphase arrest promoted release of LSD1 from chromatin, and the phosphorylation- defective mutant LSD1 (S126A) failed to dissociate from chromatin upon nocodazole treatment. Conclusions: Taken together, our findings demonstrate that phosphorylation of LSD1 at Ser-126 by PLK1 promotes its release from chromatin during mitosis. [ABSTRACT FROM AUTHOR]

Background: shRNA-mediated lethality screening is a useful tool to identify essential targets in cancer biology. Ovarian cancer (OC) is extremely heterogeneous and most cases are advanced stages at diagnosis. OC has a high response rate initially, but becomes resistant to standard chemotherapy. We previously employed high throughput global shRNA sensitization screens to identify NF-kB related pathways. Here, we re-analyzed our previous shRNA screens in an unbiased manner to identify clinically applicable molecular targets.Methods: We proceeded with siRNA lethality screening using the top 55 genes in an expanded set of 6 OC cell lines. We investigated clinical relevance of candidate targets in The Cancer Genome Atlas OC dataset. To move these findings towards the clinic, we chose four pharmacological inhibitors to recapitulate the top siRNA effects: Oxozeaenol (for MAP3K7/TAK1), BI6727 (PLK1), MK1775 (WEE1), and Lapatinib (ERBB2). Cytotoxic effects were measured by cellular viability assay, as single agents and in 2-way combinations. Co-treatments were evaluated in either sequential or simultaneous exposure to drug for short term and extended periods to simulate different treatment strategies.Results: Loss-of-function shRNA screens followed by short-term siRNA validation screens identified therapeutic targets in OC cells. Candidate genes were dysregulated in a subset of TCGA OCs although the alterations of these genes showed no statistical significance to overall survival. Pharmacological inhibitors such as Oxozeaenol, BI6727, and MK1775 showed cytotoxic effects in OC cells regardless of cisplatin responsiveness, while all OC cells tested were cytostatic to Lapatinib. Co-treatment with BI6727 and MK1775 at sub-lethal concentrations was equally potent to BI6727 alone at lethal concentrations without cellular re-growth after the drugs were washed off, suggesting the co-inhibition at reduced dosages may be more efficacious than maximal single-agent cytotoxic concentrations.Conclusions: Loss-of-function screen followed by in vitro target validation using chemical inhibitors identified clinically relevant targets. This approach has the potential to systematically refine therapeutic strategies in OC. These molecular target-driven strategies may provide additional therapeutic options for women whose tumors have become refractory to standard chemotherapy. [ABSTRACT FROM AUTHOR]

Background: Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive, fatal, childhood tumors that arise in the brainstem. DIPGs have no effective treatment, and their location and diffuse nature render them inoperable. Radiation therapy remains the only standard of care for this devastating disease. New therapeutic targets are needed to develop novel therapy for DIPG.Methods: We examined the expression of PLK1 mRNA in DIPG tumor samples through microarray analysis and found it to be up regulated versus normal pons. Using the DIPG tumor cells, we inhibited PLK1 using a clinically relevant specific inhibitor BI 6727 and evaluated the effects on, proliferation, apoptosis, induction of DNA damage and radio sensitization of the DIPG tumor cells.Results: Treatment of DIPG cell lines with BI 6727, a new generation, highly selective inhibitor of PLK1, resulted in decreased cell proliferation and a marked increase in cellular apoptosis. Cell cycle analysis showed a significant arrest in G2-M phase and a substantial increase in cell death. Treatment also resulted in an increased γH2AX expression, indicating induction of DNA damage. PLK1 inhibition resulted in radiosensitization of DIPG cells.Conclusion: These findings suggest that targeting PLK1 with small-molecule inhibitors, in combination with radiation therapy, will hold a novel strategy in the treatment of DIPG that warrants further investigation. [ABSTRACT FROM AUTHOR]

Background The Polo-like Kinase 1 (PLK1) protein regulates cell cycle progression and is overexpressed in many malignant tissues. Overexpression is associated with poor prognosis in several cancer entities, whereby expression of PLK1 shows high inter-individual variability. Although PLK1 is extensively studied, not much is known about the genetic variability of the PLK1 gene. The function of PLK1 and the expression of the corresponding gene could be influenced by genomic variations. Hence, we investigated the gene for functional polymorphisms. Such polymorphisms could be useful to investigate whether PLK1 alters the risk for and the course of cancer and they could have an impact on the response to PLK1 inhibitors. Methods The coding region, the 5' and 3'UTRs and the regulatory regions of PLK1 were systematically sequenced. We determined the allele frequencies and genotype distributions of putatively functional SNPs in 120 Caucasians and analyzed the linkage and haplotype structure using Haploview. The functional analysis included electrophoretic mobility shift assay (EMSA) for detected variants of the silencer and promoter regions and reporter assays for a 3'UTR polymorphism. Results Four putatively functional polymorphisms were detected and further analyzed, one in the silencer region (rs57973275), one in the core promoter region (rs16972787), one in intron 3 (rs40076) and one polymorphism in the 3'untranslated region (3'UTR) of PLK1 (rs27770). Alleles of rs27770 display different secondary mRNA structures and showed a distinct alleledependent difference in mRNA stability with a significantly higher reporter activity of the A allele (p < 0.01). Conclusion The present study provides evidence that at least one genomic variant of PLK1 has functional properties and influences expression of PLK1. This suggests polymorphisms of the PLK1 gene as an interesting target for further studies that might affect cancer risk, tumor progression as well as the response to PLK1 inhibitors. [ABSTRACT FROM AUTHOR]

Background: The significance of PLK1 (polo-like kinase 1) has become increasingly essential as both a biomarker and a target for cancer treatment. Here, we aimed to determine the downstream genes of PLK1 and their effects on the carcinogenesis and progression of bladder cancer., Methods: Specific siRNA was utilized to silence the target gene expression. The cell proliferation, invasion and migration of bladder cancer cells by MTT assay, BrdU assay and transwell assay. The differential expression genes were identified using Affymetrix HTA2.0 Array. The KEGG, GO and STRING analysis were used to analyze the signaling pathway and protein-protein interaction. Spearman analysis was used to analyze the correlation between protein and protein, between protein and clincopathologic characteristics., Results: PLK1 siRNA hindered the proliferation, invasion and migration of bladder cancer cells, as determined by the MTT, BrdU and transwell assays. A total of 561 differentially expressed genes were identified using an Affymetrix HTA2.0 Array in PLK1 knockdown T24 cells. According to KEGG, GO and STRING analysis, five key genes (BUB1B, CCNB1, CDC25A, FBXO5, NDC80) were determined to be involved in cell proliferation, invasion and migration. PLK1 knockdown decreased BUB1B, CCNB1, CDC25A and NDC80 expressions but increased FBXO5 expression. BUB1B, CCNB1, CDC25A and NDC80 were positively correlated with cell proliferation, invasion, migration and PLK1 expression in tissues, but FBXO5 was negatively correlated with each of those factors. The results showed that the five genes expressions were significantly correlation with the PLK1 expression in normal bladder tissues and bladder cancer tissues. Four of them (BUB1B, CCNB1, CDC25A, NDC80) were obviously positive correlations with pT stage and metastasis. But FBXO5 was negative correlated with pT stage and metastasis. Furthermore, significant correlations were found between CCNB1 or CDC25A or NDC80 and histological grade; between BUB1B or NDC80 and recurrence., Conclusion: Five downstream genes of PLK1 were associated with the regulation of cell proliferation, invasion and migration in bladder cancer. Furthermore, these genes may play important roles in bladder cancer and become important biomarkers and targets for cancer treatment.

Background: Lysine-specific histone demethylase 1 (LSD1) modulates chromatin status through demethylation of H3K4 and H3K9. It has been demonstrated that LSD1 is hyperphosphorylated and dissociates from chromatin during mitosis. However, the molecular mechanism of LSD1 detachment is unknown., Results: In this report, we found that polo-like kinase 1 (PLK1) directly interacted with LSD1 and phosphorylated LSD1 at Ser-126 . Nocodazole-induced metaphase arrest promoted release of LSD1 from chromatin, and the phosphorylation-defective mutant LSD1 (S126A) failed to dissociate from chromatin upon nocodazole treatment., Conclusions: Taken together, our findings demonstrate that phosphorylation of LSD1 at Ser-126 by PLK1 promotes its release from chromatin during mitosis.