E2F1 Facilitates the Proliferation and Stemness of Gastric Cancer Cells by Activating CDC25B Transcription and Modulating the MAPK Pathway.

Gastric cancer (GC) is a health problem that concerns people around the world. CDC25B is an essential cell cycle regulatory factor that is overexpressed in a variety of tumor cells. CDC25B plays a vital part in the progression and proliferation of malignant tumors. However, it is not yet clear that how CDC25B affects the stemness of GC cells. The study used bioinformatics to detect the expression of E2F1 and CDC25B in GC tissues and their correlation, as well as pathways enriched by CDC25B. We detected the expression of E2F1 and CDC25B in GC cell lines using quantitative reverse transcription polymerase chain reaction and tested the combination relationship between E2F1 and CDC25B using chromatin immunoprecipitation (ChIP) and dual-luciferase assays. We measured cell viability using CCK-8 assay, evaluated sphere-forming efficiency using sphere formation assay, and determined cell proliferation ability using colony formation assay. We also analyzed the expression of stemness markers and MAPK pathway-related proteins using western blot. In GC tissues and cells, CDC25B was upregulated. Silencing CDC25B could affect the MAPK pathway, thereby repressing the proliferation and stemness of GC cells. As predicted by bioinformatics, CDC25B had an upstream transcription factor, E2F1, which also had a high expression level in GC. Dual-luciferase and ChIP assays confirmed the combination relationship between the two. Rescue experiments uncovered that overexpression of CDC25B could reverse the impact induced by E2F1 knockdown on proliferation and stemness of cells. In conclusion, E2F1 could activate CDC25B transcription to regulate the MAPK pathway and enhance the proliferation and stemness of GC cells. We revealed a potential regulatory pathway of stemness of GC cells that was mediated by CDC25B, providing new ideas for improving and innovating GC treatment.

Survivin Mediates Mitotic Onset in HeLa Cells Through Activation of the Cdk1-Cdc25B Axis.

The Survivin protein has roles in repairing incorrect microtubule-kinetochore attachments at prometaphase, and the faithful execution of cytokinesis, both as part of the chromosomal passenger complex (CPC) (1). In this context, errors frequently lead to aneuploidy, polyploidy and cancer (1). Adding to these well-known roles of this protein, this paper now shows for the first time that Survivin is required for cancer cells to enter mitosis, and that, in its absence, HeLa cells accumulate at early prophase, or prior to reported before (2, 3). This early prophase blockage is demonstrated by the presence of an intact nuclear lamina and low Cdk1 activity (4). Importantly, escaping the arrest induced by Survivin abrogation leads to multiple mitotic defects, or mitotic catastrophe, and eventually cell death. Mechanistically, Cdk1 does not localize at the centrosome in the absence of Survivin pointing at an impairment in signaling through the Cdc25B-Cdk1 axis. In agreement, even though Survivin directly interacts with Cdc25B, both in vitro and in vivo, in its absence, an inactive cytosolic Cdc25B-Cdk1-Cyclin B1 complex accumulates. This flaw in Cdc25B activation can however be reversed in Survivin-depleted HeLa cell extracts to which the recombinant Survivin protein is added back. Finally, a role for Survivin in the Cdc25B-mediated activation of Cdk1 is confirmed by overriding the early prophase blockage induced in cells lacking Survivin through the expression of a gain-of-function Cdc25B mutant.

Transcription factor E2F3 activates CDC25B to regulate DNA damage and promote mitoxantrone resistance in stomach adenocarcinoma.

BACKGROUND: CDC25B, as a member of the cell cycle regulating protein family, is located in the cytoplasm and is involved in the transition of the cell cycle and mitosis. CDC25B is highly expressed in various tumors and is a newly discovered oncogene. This study aimed to investigate the impact of CDC25B on mitoxantrone resistance in stomach adenocarcinoma (STAD) and its possible mechanisms. METHODS: This study analyzed the expression of CDC25B and its potential transcription factor E2F3 in STAD, as well as the IC50 values of tumor tissues by bioinformatics analysis. Expression levels of CDC25B and E2F3 in STAD cells were measured by qRT-PCR. MTT was utilized to evaluate cell viability and IC50 values of STAD cells, and comet assay was utilized to analyze the level of DNA damage in STAD cells. Western blot was used to analyze the expression of DNA damage-related proteins. The targeting relationship between E2F3 and CDC25B was validated by dual-luciferase and ChIP assays. RESULTS: Bioinformatics analysis and molecular experiments showed that CDC25B and E2F3 were highly expressed in STAD, and CDC25B was enriched in the mismatch repair and nucleotide excision repair pathways. The IC50 values of tumor tissues with high expression of CDC25B were relatively high. Dual-luciferase and ChIP assays confirmed that CDC25B could be transcriptionally activated by E2F3. Cell experiments revealed that CDC25B promoted mitoxantrone resistance in STAD cells by regulating DNA damage. Further research found that low expression of E2F3 inhibited mitoxantrone resistance in STAD cells by DNA damage, but overexpression of CDC25B reversed the impact of E2F3 knockdown on mitoxantrone resistance in STAD cells. CONCLUSION: This study confirmed a novel mechanism by which E2F3/CDC25B mediated DNA damage to promote mitoxantrone resistance in STAD cells, providing a new therapeutic target for STAD treatment.

Control of G2 Phase Duration by CDC25B Modulates the Switch from Direct to Indirect Neurogenesis in the Neocortex.

During development, cortical neurons are produced in a temporally regulated sequence from apical progenitors, directly or indirectly, through the production of intermediate basal progenitors. The balance between these major progenitor types is critical for the production of the proper number and types of neurons, and it is thus important to decipher the cellular and molecular cues controlling this equilibrium. Here we address the role of a cell cycle regulator, the CDC25B phosphatase, in this process. We show that, in the developing mouse neocortex of both sex, deleting CDC25B in apical progenitors leads to a transient increase in the production of TBR1+ neurons at the expense of TBR2+ basal progenitors. This phenotype is associated with lengthening of the G2 phase of the cell cycle, the total cell cycle length being unaffected. Using in utero electroporation and cortical slice cultures, we demonstrate that the defect in TBR2+ basal progenitor production requires interaction with CDK1 and is because of the G2 phase lengthening in CDC25B mutants. Together, this study identifies a new role for CDC25B and G2 phase length in direct versus indirect neurogenesis at early stages of cortical development.SIGNIFICANCE STATEMENT This study is the first analysis of the function of CDC25B, a G2/M regulator, in the developing neocortex. We show that removing CDC25B function leads to a transient increase in neuronal differentiation at early stages, occurring simultaneously with a decrease in basal intermediate progenitors (bIPs). Conversely, a CDC25B gain of function promotes production of bIPs, and this is directly related to CDC25B's ability to regulate CDK1 activity. This imbalance of neuron/progenitor production is linked to a G2 phase lengthening in apical progenitors; and using pharmacological treatments on cortical slice cultures, we show that shortening the G2 phase is sufficient to enhance bIP production. Our results reveal the importance of G2 phase length regulation for neural progenitor fate determination.

Exploring the mechanism of C473D mutation on CDC25B causing weak binding affinity with CDK2/CyclinA by molecular dynamics study.

CDC25B belongs to the CDC25 family, and it plays an important part in regulating the activity of CDK/CyclinA. Studies have shown that CDC25B is closely related to cancer development. When CYS473 on CDC25B is mutated into ASP, the affinity between CDC25B and CDK2/CyclinA weakens, and their dissociation speed is greatly improved. However, the mechanism by which the CDC25BC473D mutant weakens its binding to CDK2/CyclinA is unclear. In order to study the effect of CDC25BC473D mutants on CDK2/CyclinA substrates, we constructed and verified the rationality of the CDC25BWT:CDK2/CyclinA system and CDC25BC473D:CDK2/CyclinA system and conducted molecular dynamics (MD) simulation analysis. In the post-analysis, the fluctuations of residues ARG488-SER499, LYS541-TRP550 on CDC25B and residues ASP206-ASP210 on CDK2 were massive in the mutant CDC25BC473D:CDK2/CyclinA system. And the interactions between residue ARG492 and residue GLU208, residue ARG544 and residue GLU42, residue ARG544 and TRP550 were weakened in the mutant CDC25BC473D:CDK2/CyclinA system. The results showed that when CYS473 on CDC25B was mutated into ASP473, the mutant CDC25BC473D:CDK2/CyclinA system was less stable than the wild-type CDC25BWT:CDK2/CyclinA system. Finally, active site CYS473 of CDC25B was speculated to be the key residue, which had great effects on the binding between CDC25BCYS473 and CDK2 in the CDC25BC473D:CDK2/CyclinA system. Consequently, overall analyses appeared in this study ultimately provided a useful understanding of the weak interactions between CDC25BCYS473D and CDK2/CyclinA.Communicated by Ramaswamy H. Sarma.

Fosfatase Cdc25B: Interações transientes intramoleculares e complexação com pequenos ligantes / Cdc25B phosphatase: Transient intramolecular interactions and small molecules complexation

Proteínas tirosina-fosfatase (PTPs) possuem papel fundamental na regulação da transdução de sinais e estão envolvidas em diversos processos fundamentais do ciclo celular. As Cdc25 (Cell Division Cycle 25) são fosfatases duais encontradas em todos os organismos eucarióticos e atuam em checkpoints do ciclo celular, permitindo ou inibindo o prosseguimento deste. Este grupo de proteínas pertence à classe de PTPs com atividade baseada em cisteína, apresenta domínio catalítico altamente conservado assim como o motivo catalítico, P-loop. Devido sua função, as Cdc25 são consideradas possíveis alvos terapêuticos para tratamento de câncer e sua interação com pequenas moléculas e inibidores tem sido investigada de forma que análises estruturais e de ligação das Cdc25 com inibidores podem elucidar aspectos importantes do mecanismo de ação destes além de direcionar para o desenho racional de fármacos. Interações cátion-π são interações intra ou intermoleculares não-covalentes que ocorrem entre uma espécie química catiônica, como o grupo guanidino de argininas, e uma das faces de um sistema π rico em elétrons, como dos anéis indólicos de triptofanos. Apesar de pouco discutidas na literatura, quando em comparação às interações não-covalentes mais convencionais, do ponto de vista energético as interações cátion-π são tão importantes na estruturação de proteínas quanto às ligações de hidrogênio ou pontes salinas. De fato estas interações são observadas com frequência em estruturas proteicas resolvidas. O domínio catalítico da Cdc25B possui diversas argininas expostas em sua superfície e um único resíduo de triptofano localizado na região C-terminal flexível, muito próximo do sítio catalítico da proteína. A flexibilidade de proteínas ou de regiões proteicas apresenta importante papel no reconhecimento entre biomoléculas participantes de vias de sinalização e tem sido muito estudada atualmente. Aqui, simulações de dinâmica molecular, experimentos de 1H-15N HSQC RMN, ensaios de cinética de inibição e de ancoragem molecular, evidenciam a existência de contatos cátion-π transientes na superfície de um importante membro da família das Cdc25, a Cdc25B, e de sítios de interação entre inibidores testados e a proteína com destaque a sítios na proximidades do P-loop, região próxima ao C-terminal desordenado, onde se demonstra estabilidade da interação com os pequenos ligantes

Protein tyrosine phosphatase (PTPs) play a fundamental role in the regulation of signal transduction and are involved in several fundamental processes of the cell cycle. Cdc25 (Cell Division Cycle 25) are dual phosphatases found in all eukaryotic organisms and act at checkpoints of the cell cycle, allowing or inhibiting its progression. This group of proteins belongs to the class of PTPs with cysteine-based activity, presenting a highly conserved catalytic domain as well as the catalytic motif, P-loop. Due to their function, Cdc25 are considered possible therapeutic targets for cancer treatment and their interaction with small molecules and inhibitors has been investigated so that structural and binding analyzes of Cdc25 with inhibitors can elucidate important aspects of their mechanism of action besides directing to rational drug design. Cation-π interactions are non-covalent intra- or intermolecular interactions that occur between a cationic chemical species, such as the guanidino group of arginines, and one of the faces of an electron-rich system, such as the indole rings of tryptophans. Although little discussed in the literature, when compared to more conventional non-covalent interactions, from the energetic point of view, cation-π interactions are as important in the structuring of proteins as hydrogen bonds or salt bridges. In fact, these interactions are frequently observed in solved protein structures. The catalytic domain of Cdc25B has several arginines exposed on its surface and a single tryptophan residue located in the flexible C-terminal region, very close to the catalytic site of the protein. The flexibility of proteins or protein regions plays an important role in the recognition between biomolecules participating in signaling pathways and has been extensively studied today. Here, molecular dynamics simulations, 1H-15N HSQC NMR experiments, inhibition kinetics and molecular anchoring assays, evidence the existence of transient cation-π contacts on the surface of an important member of the Cdc25 family, Cdc25B, and of sites of interaction between tested inhibitors and the protein, with emphasis on sites in the vicinity of the P-loop, a region close to the disordered C-terminus, where stability of the interaction with the small ligands is demonstrated

Corrigendum: Dual-specificity phosphatase CDC25B was inhibited by natural product HB-21 through covalently binding to the active site.

[This corrects the article DOI: 10.3389/fchem.2018.00531.].

CDC25B Inhibition by Menadione: A Potential New Therapeutical Approach.

Gastric cancer (GC) is the fifth most common type of tumor and the third leading cause of cancer death worldwide. The evolution of gastric carcinogenesis is still poorly understood and, for this reason, preclinical research protocols were established that included the development of gastric cancer cell lines and the establishment of models of gastric carcinogenesis in non-human primates such as Sapajus apella. A comprehensive literature search was performed in relevant databases such as PubMed, ResearchGate, and Google Scholar to identify studies related to the topic. After an in-depth study of these reports, significant data were collected and compiled under appropriate headings. The main result of the studies carried out by the group on GC is the demonstration of the MYC gene overexpression as a common phenomenon in stomach carcinogenesis. Furthermore, we revealed that reducing the expression of the CDC25B gene, regulated by the MYC protein, is a therapeutic strategy against stomach tumors. This review article reveals preclinical evidence that treatment with menadione in experimental models of gastric tumorigenesis, in vivo and in vitro, inhibits the action of the phosphatase CDC25B and, consequently, prevents cell proliferation, invasion, and migration.

CDC25B is required for the metaphase I-metaphase II transition in mouse oocytes.

Mammalian oocytes are arrested at meiotic prophase I. The dual-specificity phosphatase CDC25B is essential for cyclin-dependent kinase 1 (CDK1) activation that drives resumption of meiosis. CDC25B reverses the inhibitory effect of the protein kinases WEE1 and MYT1 on CDK1 activation. Cdc25b-/- female mice are infertile because oocytes cannot activate CDK1. To identify a role for CDC25B following resumption of meiosis, we restored CDK1 activation in Cdc25b-/- oocytes by inhibiting WEE1 and MYT1, or expressing EGFP-CDC25A or constitutively active EGFP-CDK1 from microinjected complementary RNAs. Forced CDK1 activation in Cdc25b-/- oocytes allowed resumption of meiosis, but oocytes mostly arrested at metaphase I (MI) with intact spindles. Similarly, approximately a third of Cdc25b+/- oocytes with a reduced amount of CDC25B arrested in MI. MI-arrested Cdc25b-/- oocytes also displayed a transient decrease in CDK1 activity similar to Cdc25b+/+ oocytes during the MI-MII transition, whereas Cdc25b+/- oocytes exhibited only a partial anaphase-promoting complex/cyclosome activation and anaphase I entry. Thus, CDC25B is necessary for the resumption of meiosis and the MI-MII transition.

METTL3 modulates m6A modification of CDC25B and promotes head and neck squamous cell carcinoma malignant progression.

BACKGROUND: N6-methyladenosine (m6A) RNA methylation and its methyltransferase METTL3 have been widely reported to be involved in different cancers by regulating RNA metabolism and function. Here, we aimed to explore the biological function and clinical significance of m6A modification and METTL3 in head and neck squamous cell carcinoma (HNSCC). METHODS: The prognostic value of METTL3 expression was evaluated using tissue microarray and immunohistochemical staining analyses in a human HNSCC cohort. The biological role and mechanism of METTL3 in HNSCC tumour growth, metastasis and angiogenesis were determined in vitro and in vivo. RESULTS: M6A levels and METTL3 expressions in HNSCC tissues were significantly increased compared with paired adjacent tissues. Meanwhile, METTL3 was an independent risk factor for the prognosis of HNSCC patients. Moreover, METTL3 overexpression promoted HNSCC cell proliferation, migration, invasion, and angiogenesis, while knockdown of METTL3 had an opposite effect in vivo and in vitro. Mechanistically, METTL3 enhanced the m6A modification of CDC25B mRNA, which maintained its stability and upregulated its expression, thereby activating G2/M phase of cell cycle and leading to HNSCC malignant progression. CONCLUSIONS: METTL3 may be a potential prognostic biomarker and therapeutic target for HNSCC.

Cyclin-dependent kinase 5 promotes the growth of tongue squamous cell carcinoma through the microRNA 513c-5p/cell division cycle 25B pathway and is associated with a poor prognosis.

BACKGROUND: The objective of this study was to investigate the role and molecular mechanism of cyclin-dependent kinase 5 (CDK5) in regulating the growth of tongue squamous cell carcinoma (TSCC). METHODS: The authors used multiple methods to detect the levels of CDK5 expression in samples of TSCC and to explore the relation between CDK5 expression and various clinicopathologic factors. In vivo and in vitro cell experiments were performed to detect the proliferation, invasion, and migration of TSCC cells with CDK5 knockdown or overexpression. These studies verified that CDK5 regulates the occurrence and development of TSCC cells through the microRNA 513c-5p/cell division cycle 25B pathway. RESULTS: An elevated level of CDK5 expression in TSCC tissues was identified as an independent risk factor affecting TSCC growth and patient prognosis. Patients who had TSCC with low levels of CDK5 expression had a higher survival rate than those with high levels. Knockdown of CDK5 reduced the proliferation, migration, and invasion of TSCC cells both in vitro and in vivo. In addition, the authors observed that CDK5 regulated the growth of TSCC through the microRNA 513c-5p/cell division cycle C25B pathway. CONCLUSIONS: CDK5 functions as an oncogene in TSCC and might serve as a molecular marker for use in the diagnosis and treatment of TSCC. LAY SUMMARY: Tongue squamous cell carcinoma (TSCC) is 1 of the most common malignant tumors of the head and neck, and the survival rate of patients with tongue cancer has been very low. Therefore, it is important to study the molecular mechanism of TSCC progression to identify biomarkers that can be used to improve its clinical diagnosis and treatment. Cyclin-dependent kinase 5 (CDK5) is an atypical member of the cyclin-dependent kinase family and is involved in regulating the cell cycle. Changes in the cell cycle are of great significance for the occurrence and development of tumor cells; and, in recent years, increasing evidence has suggested that CDK5 exists in a disordered state in cancer cells. In this study, the authors demonstrate that CDK5 functions as an oncogene in TSCC and might serve as a molecular marker for use in the diagnosis and treatment of TSCC.

Aß monomers protect lens epithelial cells against oxidative stress by upregulating CDC25B.

Our previous studies showed high ß-amyloid (Aß) expression levels in the nuclei of the lens epithelial cells (LECs) of healthy subjects and revealed that Aß monomers could protect LECs from oxidative damage. Here, we further explored the mechanism by which Aß monomers act as transcription factors to regulate the oxidative stress of LECs through high-throughput studies. First, we compared the Aß-binding sites in the lens epithelia (LE) of age-related cataract patients with those in the LE of healthy donors via chromatin immunoprecipitation-sequencing (ChIP-seq), and we identified comparable numbers (1648 and 1445, respectively) of Aß peaks. Then, the KEGG tool was used for gene function enrichment analysis of these genes, which were more highly enriched in healthy LE. Combining the literature review with these KEGG analysis results, in the current study, we chose four target genes related to oxidative stress, namely, CDC25B, SOS2, CTNNA1 and Cox6a1. Then, ChIP-PCR assays, dual-luciferase reporter assays, real-time PCR and Western blotting were performed to validate the regulatory effects of Aß on these targets. Our data suggested that Aß monomers could upregulate the mRNA and protein expression levels of CDC25B in LECs. We also confirmed that Aß monomers could activate the Akt/Nrf2 pathway in a CDC25B-dependent manner by knockdown experiments in cultured LECs. Furthermore, we performed functional verification of the CDC25B-mediated protective effects of Aß monomers against oxidative stress. We observed that Aß monomers significantly improved the antioxidant capacity (the GSH level, SOD activity and total antioxidant capacity) and decreased the oxidative stress (the ROS and MDA levels) of LECs, while CDC25B knockdown decreased the antioxidant effects of Aß, disrupting redox homeostasis. Therefore, we propose that Aß monomers activate the Akt/Nrf2 pathway by upregulating CDC25B expression, increase various downstream antioxidant enzyme levels, maintain peroxidation-antioxidant homeostasis in LECs, and prevent the cell damage caused by oxidative stress.

Cdc25B is transcriptionally inhibited by IER5 through the NF-YB transcription factor in irradiation-treated HeLa cells.

Cervical cancer (CC) is a type of pelvic malignant tumor that severely threatens women's health. Current evidence suggests that IER5, as a potential radiosensitizer, promotes irradiation-induced apoptosis in CC tissues in patients undergoing chemoradiotherapy. IER5 has been shown to be involved in the G2/M-phase transition. In the present study, we used Cdc25B as the breakthrough point to explore the underlying mechanism of IER5 in the cell cycle regulation of radiation-damaged HeLa cells. IER5 was evidently upregulated after irradiation, but Cdc25B was significantly downregulated. In monoclonal IER5-silenced HeLa cells, irradiation-induced downregulation of Cdc25B was attenuated. The effect of irradiation on Cdc25B promoter activity was determined by dual-luciferase reporter assays. The response elements on the Cdc25B promoter related to irradiation were predicted by JASPAR. These conserved sequences were mutated individually or in combination by splicing-by-overlap extension PCR, and their function was confirmed by dual-luciferase reporter assays. The enrichment efficiency of transcription factors after irradiation was determined by chromatin immunoprecipitation (ChIP) assay. Both Sp1/Sp3 and NF-YB binding sites were involved in irradiation-mediated regulation of Cdc25B. IER5 was involved in irradiation-mediated regulation of Cdc25B through the NF-YB binding site. Furthermore, ChIP assays showed that IER5 bound to the Cdc25B promoter, and the binding of IER5 to the Cdc25B promoter region in irradiation-induced HeLa cells induced the release of the coactivator p300 through interaction with NF-YB. Taken together, these findings indicate that IER5 is the transcriptional repressor that accelerates the downregulation of Cdc25B expression after irradiation.

Multi-Epitope-Based Vaccines for Colon Cancer Treatment and Prevention.

Background: Overexpression of nonmutated proteins involved in oncogenesis is a mechanism by which such proteins become immunogenic. We questioned whether overexpressed colorectal cancer associated proteins found at higher incidence and associated with poor prognosis could be effective vaccine antigens. We explored whether vaccines targeting these proteins could inhibit the development of intestinal tumors in the azoxymethane (AOM)-induced colon model and APC Min mice. Methods: Humoral immunity was evaluated by ELISA. Web-based algorithms identified putative Class II binding epitopes of the antigens. Peptide and protein specific T-cells were identified from human peripheral blood mononuclear cells using IFN-gamma ELISPOT. Peptides highly homologous between mouse and man were formulated into vaccines and tested for immunogenicity in mice and in vivo tumor challenge. Mice treated with AOM and APC Min transgenic mice were vaccinated and monitored for tumors. Results: Serum IgG for CDC25B, COX2, RCAS1, and FASCIN1 was significantly elevated in colorectal cancer patient sera compared to volunteers (CDC25B p=0.002, COX-2 p=0.001, FASCIN1 and RCAS1 p<0.0001). Epitopes predicted to bind to human class II MHC were identified for each protein and T-cells specific for both the peptides and corresponding recombinant protein were generated from human lymphocytes validating these proteins as human antigens. Some peptides were highly homologous between mouse and humans and after immunization, mice developed both peptide and protein specific IFN-γ-secreting cell responses to CDC25B, COX2 and RCAS1, but not FASCIN1. FVB/nJ mice immunized with CDC25B or COX2 peptides showed significant inhibition of growth of the syngeneic MC38 tumor compared to control (p<0.0001). RCAS1 peptide vaccination showed no anti-tumor effect. In the prophylactic setting, after immunization with CDC25B or COX2 peptides mice treated with AOM developed significantly fewer tumors as compared to controls (p<0.0002) with 50% of mice remaining tumor free in each antigen group. APC Min mice immunized with CDC25B or COX2 peptides developed fewer small bowel tumors as compared to controls (p=0.01 and p=0.02 respectively). Conclusions: Immunization with CDC25B and COX2 epitopes consistently suppressed tumor development in each model evaluated. These data lay the foundation for the development of multi-antigen vaccines for the treatment and prevention of colorectal cancer.

Molecular dynamics study of CDC25BR492L mutant causing the activity decrease of CDC25B.

Cell division cycle 25B (CDC25B) was responsible for regulating the various stages of cell division in the cell cycle. R492L was one of the common types of CDC25B mutants. Researches showed that compared to CDC25BWT, CDC25BR492L mutant had a ∼100-fold reduction in the rate constant for forming phosphatase intermediate (k2). However, the molecular basis of how the CDC25BR492L mutant influenced the process of binding between CDC25B and CDK2/CyclinA was not yet known. Therefore, the optimizations of three-dimensional structure of the CDC25BWT-CDK2/CyclinA system and the CDC25BR492L-CDK2/CyclinA system were constructed by ZDOCK and RDOCK, and five methods were employed to verify the reasonability of the docking structure. Then the molecular dynamics simulations on the two systems were performed to explore the reason why CDC25BR492L mutant caused the weak interactions between CDC25BR492L and CDK2/CyclinA, respectively. The remote docking site (Arg488-Tyr497) and the second active site (Lys538-Arg544) of CDC25B were observed to have high fluctuations in the CDC25BR492L-CDK2/CyclinA system with post-analysis, where the high fluctuation of these two regions resulted in weak interactions between CD25B and CDK2. In addition, Asp38-Glu42 and Asp206-Asp210 of CDK2 showed the slightly descending fluctuation, and CDK2 revealed an enhanced the self-interaction, which made CDK2 keep a relatively stable state in the CDC25BR492L-CDK2/CyclinA system. Finally, Leu492 of CDC25B was speculated to be the key residue, which had great effects on the binding between CDC25BR492L and CDK2 in the CDC25BR492L-CDK2/CyclinA system. Consequently, overall analyses appeared in this study ultimately offered a helpful understanding of the weak interactions between CDC25BR492L and CDK2.

Design, synthesis, and functional evaluation of triazine-based bivalent agents that simultaneously target the active site and hot spot of phosphatase Cdc25B.

Cdc25B phosphatase catalyzes the dephosphorylation and activation of cyclin-dependent kinases 2 (CDK2/CycA) and their overexpression has been reported in cancers. Although Cdc25B has received much attention as a drug target, its flat and featureless surface makes it challenging to develop new agents targeting this protein. In this study, we investigated the rational design of a series of bivalent triazine-based derivatives with the aim of simultaneously targeting the active site and the remote hotspot critical for the interaction with CDK2/CycA. Compounds 1e and 10, containing aromatic residues, were shown to inhibit Cdc25B activity selectively over Cdc25A at low micromolar concentration.

New possible silver lining for pancreatic cancer therapy: Hydrogen sulfide and its donors.

As one of the most lethal diseases, pancreatic cancer shows a dismal overall prognosis and high resistance to most treatment modalities. Furthermore, pancreatic cancer escapes early detection during the curable period because early symptoms rarely emerge and specific markers for this disease have not been found. Although combinations of new drugs, multimodal therapies, and adjuvants prolong survival, most patients still relapse after surgery and eventually die. Consequently, the search for more effective treatments for pancreatic cancer is highly relevant and justified. As a newly re-discovered mediator of gasotransmission, hydrogen sulfide (H2S) undertakes essential functions, encompassing various signaling complexes that occupy key processes in human biology. Accumulating evidence indicates that H2S exhibits bimodal modulation of cancer development. Thus, endogenous or low levels of exogenous H2S are thought to promote cancer, whereas high doses of exogenous H2S suppress tumor proliferation. Similarly, inhibition of endogenous H2S production also suppresses tumor proliferation. Accordingly, H2S biosynthesis inhibitors and H2S supplementation (H2S donors) are two distinct strategies for the treatment of cancer. Unfortunately, modulation of endogenous H2S on pancreatic cancer has not been studied so far. However, H2S donors and their derivatives have been extensively studied as potential therapeutic agents for pancreatic cancer therapy by inhibiting cell proliferation, inducing apoptosis, arresting cell cycle, and suppressing invasion and migration through exploiting multiple signaling pathways. As far as we know, there is no review of the effects of H2S donors on pancreatic cancer. Based on these concerns, the therapeutic effects of some H2S donors and NO-H2S dual donors on pancreatic cancer were summarized in this paper. Exogenous H2S donors may be promising compounds for pancreatic cancer treatment.

CDC25B induces cellular senescence and correlates with tumor suppression in a p53-dependent manner.

The phosphatase cell division cycle 25B (Cdc25B) regulates cell cycle progression. Increased Cdc25B levels are often detected in cancer cell lines and human cancers and have been implicated in contributing to tumor growth, potentially by providing cancer cells with the ability to bypass checkpoint controls. However, the specific mechanism by which increased Cdc25B impacts tumor progression is not clear. Here we analyzed The Cancer Genome Atlas (TCGA) database and found that patients with high CDC25B expression had the expected poor survival. However, we also found that high CDC25B expression had a p53-dependent tumor suppressive effect in lung cancer and possibly several other cancer types. Looking in more detail at the tumor suppressive function of Cdc25B, we found that increased Cdc25B expression caused inhibition of cell growth in human normal fibroblasts. This effect was not due to alteration of specific cell cycle stage or inhibition of apoptosis, nor by induction of the DNA damage response. Instead, increased CDC25B expression led cells into senescence. We also found that p53 was required to induce senescence, which might explain the p53-dependent tumor suppressive function of Cdc25B. Mechanistically, we found that the Cdc25B phosphatase activity was required to induce senescence. Further analysis also found that Cdc25B stabilized p53 through binding and dephosphorylating p53. Together, this study identified a tumor-suppressive function of Cdc25B that is mediated through a p53-dependent senescence pathway.

LncRNA FAM83A-AS1 promotes ESCC progression by regulating miR-214/CDC25B axis.

Background: Recent researches have pinpointed that long non-coding RNA (lncRNA) was tightly related to the carcinogenesis. However, the function of lncRNA in esophageal cell squamous carcinoma (ESCC) remains to be explored. In the current study, we assessed the expression pattern and the biological function of FAM83A-AS1 in ESCC. Methods: qRT-PCR was used to detect the expression of FAM83A-AS1, miR-214, and CDC25B expression in ESCC tissues and cell lines. CCK-8, transwell, apoptosis and cell cycle assays were performed to define the function of FAM83A-AS1 in ESCC cells. Furthermore, the regulation of miR-214 by FAM83A-AS1 was defined by qRT- PCR and rescue assays. In addition, the association between CDC25B, miR-214, CDC25B was confirmed by qRT-PCR. Results: Here, we discovered that FAM83A-AS1 was strongly expressed in ESCC tissues. FAM83A-AS1 abundance was associated with TNM stages and the differentiation grade of ESCC patients. The receiver operating characteristic curve (ROC) analysis indicated the high accuracy of FAM83A-AS1 in ESCC diagnosis. Functionally, inhibiting FAM83A-AS1 repressed cell proliferation, migration, and invasion in ESCC. In addition, we found that FAM83A-AS1 accelerated the cell cycle while inhibited cell apoptosis. Mechanistically, we found that FAM83A-AS1 regulated miR-214 expression, and there was a negative correlation between miR-214 and FAM83A-AS1 in ESCC. Rescue assay indicated that miR-214 could impair the suppressing effect of cell migration induced by FAM83A-AS1 depletion. Furthermore, CDC25B was a direct target of miR-214, and FAM83A-AS1 enhanced CDC25B expression while miR-214 positively CDC25B expression in ESCC. Conclusions: Collectively, we concluded that FAM83A-AS1 facilitated ESCC progression by regulating the miR-214/CDC25B axis. Our study showed FAM83A-AS1 may act as a promising target for ESCC diagnosis and therapy.

One-Pot Green Synthesis of Acridine Alkaloid Derivatives and Screening of in vitro Anti-cancer Activity Against Cdc25b and SHP1.

AIM: To develop anti-cancer active pharmaceutical intermediates. BACKGROUND: Acridone derivatives possess a wide range of pharmacological activities: 1) they intercalate DNA and 2) form a covalent bond with DNA. OBJECTIVE: To screen in vitro anti-cancer activity against Cdc25b and SHP1 of new acridone derivatives and preliminary study on the structure-activity relationship. MATERIALS AND METHODS: The synthesis of new acridone derivatives and in vitro evaluation of their anti-cancer activity on Cdc25b and SHP1 was achieved. Natural products that contain acridine structures, such as cystodytin A and acronycine, are isolated from certain marine (tunicates & ascidians, sponges, sea anemones) and plant (bark of Australian scrub ash tree) species. Herein, we report the efficient one-pot green synthesis of twelve novel 3,4-dihydro-1 (2H) acridone derivatives, using montmorillonite K10 as the catalyst and iron/citric acid in water. Also, their inhibitory activity against Cdc25B and SHP1 is examined, in which specific derivatives show enhanced inhibitory activity compared to others. RESULTS AND DISCUSSION: Twelve new acridone derivatives were prepared, starting from 2-nitrobenzaldehyde derivatives and 1, 3-cyclohexanedione derivatives, which exhibited substantial anti-cancer activity against Cdc25b and SHP1 cells. CONCLUSION: Preliminary studies on the structure-activity relationship have shown the influence of the structural parameters and, in particular, the nature of the substituent on aromatic ring structure and cyclohexanone. Other: Further study on the structure-activity relationship is required.