Cyclin-dependent Kinase Inhibitor Protein Research Articles

MiR-192–5p targets cell cycle regulation in diabetic kidney disease via cyclin-dependent kinase inhibitor 3

Diabetic kidney disease (DKD), a.k.a diabetic nephropathy, is a leading cause of end-stage renal disease. However, in a fair percentage of patients with type-2 diabetes, renal involvement also occurs due to non-diabetic reasons (non-diabetic kidney disease, NDKD). In this study, we identified miRNA-mRNA regulatory networks specific to human DKD pathogenesis. miRNA profiling of the renal biopsy from cases (DKD, n = 5), disease controls (T2DM with NDKD, n = 6), and non-diabetic, non-CKD controls (patients undergoing nephrectomy for renal cancer, n = 3) revealed 68 DKD-specific miRNA regulation. Sixteen target mRNAs of these DKD-miRNAs were found to have a negative association with the estimated glomerular filtration rate (eGFR) in patients with DKD. The renal gene expression and eGFR data of DKD patients (n = 10–18) in the NephroSeq database were used. Based on these findings, 11 miRNA-mRNA regulatory networks were constructed for human DKD pathogenesis. Of these, in-vitro validation of miR-192-5p- CDKN3 (Cell cycle-dependent kinase inhibitor 3) network was done as miR-192–5p exhibited a maximum number of target genes in the identified DKD regulatory networks, and CDKN3 appeared as a novel target of miR-192–5p in our study. We demonstrated that miR-192–5p overexpression or knockdown of CDKN3 attenuated high glucose-induced apoptosis, fibrotic gene expression, cell hypertrophy, and cell cycle dysregulation and improved viability of proximal tubular cells. Moreover, miR-192–5p overexpression significantly inhibited CDKN3 mRNA and protein expression in proximal tubular cells. Overall, 11 miRNA-mRNA regulatory networks were predicted for human DKD pathogenesis; among these, the association of miR-192-5p- CDKN3 network DKD pathogenesis was confirmed in proximal tubular cell culture.

AB003. Clinical analysis of central nervous system (CNS) World Health Organization (WHO) grade 4 gliomas with IDH-mutant versus IDH-wildtype focused on CDKN2A homozygous deletion.

We are primarily investigating the prognostic role of cell-cycle-dependent kinase inhibitor (CDKN)-2A homozygous deletion in central nervous system (CNS) World Health Organization (WHO) grade 4 gliomas. Additionally, traditional prognostic factors for grade 4 gliomas will be examined, and our results will be validated. We conducted a retrospective analysis of glioma cohorts in our institute. Medical records were reviewed for 142 glioblastoma patients for 15 years, and pathological slides were examined again for the updated diagnosis according to the 2021 WHO classification of CNS tumors. The isocitrate dehydrase (IDH) mutation and CDKN2A deletion were examined by next generation sequencing (NGS) analysis using ONCO accuPanel®. Traditional prognostic factors including age, WHO performance status, extent of resection, and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation were examined. After the exclusion of 6 patients with poor status of pathologic samples, 136 glioblastoma that were diagnosed by previous WHO criteria were changed into 29 (21.3%) astrocytoma, IDH-mutant, CNS WHO grade 4 and 107 (78.7%) glioblastoma, IDH-wildtype, CNS WHO grade 4. Among them, 61 patients (56.0%) had CDKN2A deletion. Group A with IDH-wildtype and CDKN2A deletion had a mean overall survival (OS) of 15.70 months [95% confident interval (CI): 13.86-17.54], group B with IDH-mutant and CDKN2A deletion had a mean OS of 19.37 months (95% CI: 13.43-25.30), group C with IDH-wildtype and intact CDKN2A had a mean OS of 22.63 months (95% CI: 20.10-25.17), and group D with IDH-mutant and intact CDKN2A had a mean OS of 33.38 months (95% CI: 29.35-37.40). Multifactor analysis showed following factors were independently associated with OS: age [≥50 vs. <50 years; hazard ratio (HR) 4.642], extent of resection (gross total resection vs. others; HR 5.523), WHO performance (0, 1 vs. 2; HR 5.007), MGMT promoter methylation, (methylated vs. unmethylated; HR 5.075), IDH mutation (mutant vs. wildtype; HR 6.358), and CDKN2A deletion (absence vs. presence; HR 13.452). The presenting study suggests that CDKN2A deletion should play a powerful prognostic role in CNS WHO grade 4 gliomas as well as low-grade glioma. Even if CNS WHO grade 4 gliomas had mutant IDH, they can have poor clinical outcomes due to CDKN2A deletion.

O-GlcNAcylation of E3 ubiquitin ligase SKP2 promotes hepatocellular carcinoma proliferation.

O-linked-β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) and ubiquitination are critical posttranslational modifications that regulate tumor development and progression. The continuous progression of the cell cycle is the fundamental cause of tumor proliferation. S-phase kinase-associated protein 2 (SKP2), an important E3 ubiquitin ligase, assumes a pivotal function in the regulation of the cell cycle. However, it is still unclear whether SKP2 is an effector of O-GlcNAcylation that affects tumor progression. In this study, we found that SKP2 interacted with O-GlcNAc transferase (OGT) and was highly O-GlcNAcylated in hepatocellular carcinoma (HCC). Mechanistically, the O-GlcNAcylation at Ser34 stabilized SKP2 by reducing its ubiquitination and degradation mediated by APC-CDH1. Moreover, the O-GlcNAcylation of SKP2 enhanced its binding ability with SKP1, thereby enhancing its ubiquitin ligase function. Consequently, SKP2 facilitated the transition from the G1-S phase of the cell cycle by promoting the ubiquitin degradation of cell cycle-dependent kinase inhibitors p27 and p21. Additionally, targeting the O-GlcNAcylation of SKP2 significantly suppressed the proliferation of HCC. Altogether, our findings reveal that O-GlcNAcylation, a novel posttranslational modification of SKP2, plays a crucial role in promoting HCC proliferation, and targeting the O-GlcNAcylation of SKP2 may become a new therapeutic strategy to impede the progression of HCC.

Long-term administration of royal jelly regulates age-related disorders and improves gut function in naturally aging mice.

A natural aging mouse model can exhibit physiological characteristics that closely resemble those of human aging. Through long-term observation, it reflects the occurrence and development of the aging process more accurately. Although numerous beneficial effects of royal jelly (RJ) have been extensively demonstrated in multiple experimental models, the effects of RJ on naturally aging mice have not yet been investigated. In this study, middle-aged male C57BL/6J mice were given RJ for 9 consecutive months to investigate its impact on the intestinal barrier function, gut microbiota, short-chain fatty acids (SCFAs) content and possible mechanisms. The results confirmed that RJ modulated serum lipids by reducing the levels of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C). Additionally, it protected the liver by increasing antioxidant enzyme levels while decreasing inflammatory cytokines TNF-α (by 51.97%), IL-6 (by 29.73%), and IL-1β (by 43.89%). Furthermore, RJ inhibited the expression of cell cycle-dependent kinase inhibitors including p16, p21, and p53. Importantly, RJ ameliorated gut dysfunctions by inhibiting reduction of tight junction proteins and reducing inflammatory cytokines content in the colon. We also observed an alteration in gut microbiota characterized by an elevated ratio of Firmicutes to Bacteroides (F/B) along with increased abundance of beneficial bacteria, i.e., Lachnospiraceae NK4A136 and Akkermansia. Correlation analysis revealed positive associations between most bacterial genera and SCFAs production. Functional profiling of gut microbiota composition indicated that RJ intervention regulated amino acid metabolism, glycan biosynthesis, and cofactor/vitamin metabolism. Overall, our findings provide an effective dietary intervention strategy for modulating age-associated frailty through the modulation of the gut microbiota.

CDKN2B-AS1 gene rs4977574 polymorphism in the severity of coronary artery disease in the Kazakh population

Coronary artery disease (CAD) is one of the leading diseases contributing to mortality. Although it has a hereditary nature, its genetic etiology remains unclear. Recently, many studies showed genetic risk factors using genome-wide association studies, and gene variant association with CAD. Despite the recent breakthroughs on various single nucleotide polymorphisms (SNP) linked to CAD, encompassing genes affecting metabolic disorders, influencing endothelial and smooth muscle dysfunctions, leading to plaque formation and myocardial infarction, most of those SNPs` functions remain to be pinpointed. Many studies showed significant associations between rs4977574 polymorphism of cyclin-dependent protein kinase inhibitors antisense RNA 1 (CDKN2B-AS1) gene on CAD in various ethnic groups. This review discusses the potential link between the CDKN2B-AS1 gene rs4977574 polymorphism and CAD in the Kazakh population.

Analysis of ANRIL Isoforms and Key Genes in Patients with Severe Coronary Artery Disease.

ANRIL (Antisense Noncoding RNA in the INK4 Locus), also named CDKN2B-AS1, is a long non-coding RNA with outstanding functions that regulates genes involved in atherosclerosis development. ANRIL genotypes and the expression of linear and circular isoforms have been associated with coronary artery disease (CAD). The CDKN2A and the CDKN2B genes at the CDKN2A/B locus encode the Cyclin-Dependent Kinase inhibitor protein (CDKI) p16INK4a and the p53 regulatory protein p14ARF, which are involved in cell cycle regulation, aging, senescence, and apoptosis. Abnormal ANRIL expression regulates vascular endothelial growth factor (VEGF) gene expression, and upregulated Vascular Endothelial Growth Factor (VEGF) promotes angiogenesis by activating the NF-κB signaling pathway. Here, we explored associations between determinations of the linear, circular, and linear-to-circular ANRIL gene expression ratio, CDKN2A, VEGF and its receptor kinase insert domain-containing receptor (KDR) and cardiovascular risk factors and all-cause mortality in high-risk coronary patients before they undergo coronary artery bypass grafting surgery (CABG). We found that the expression of ANRIL isoforms may help in the prediction of CAD outcomes. Linear isoforms were correlated with a worse cardiovascular risk profile while the expression of circular isoforms of ANRIL correlated with a decrease in oxidative stress. However, the determination of the linear versus circular ratio of ANRIL did not report additional information to that determined by the evaluation of individual isoforms. Although the expressions of the VEFG and KDR genes correlated with a decrease in oxidative stress, in binary logistic regression analysis it was observed that only the expression of linear isoforms of ANRIL and VEGF significantly contributed to the prediction of the number of surgical revascularizations.

Protein Kinase C Epsilon Overexpression in Prostate Adenocarcinoma is Associated with Oncogenesis

Background: PKCε, an isozyme of serine-threonine kinase, has been implicated in epithelial cancer metastasis and progression. This study investigates the impact of the oncogenic PKCε, overexpressed abnormally in human Prostate tumor samples and cell lines, to understand its efficacy. Methods: The microarray dataset, GSE86257, was processed for normalization. The identification of upregulated and downregulated genes was based on FDR &gt;1 and p &lt;0.05 values. Cytoscape analysis and functional enrichment of significant genes were done. The identified genes were validated on the TCGA dataset and survival analysis was performed by Kaplan-Meier analysis. Results: A total of 1524 DEGs were identified with 728 upregulated genes and 818 downregulated genes. The two significant modules with MCODE score:9.0 and Venn analysis provided cyclin-dependent kinase inhibitor protein (CDK1), Cyclin B1 (CCNB1), Phospholipase C Gamma 1 (PLCG1), Cyclin Dependent Kinase 9 (CDK9), Phosphoinositide-3-Kinase Regulatory Subunit 3 (PIK3R3), H4 Clustered Histone 6 (H4C6), Phospholipase C Gamma 2 (PLCG2) as most interacting genes. TCGA data analysis and Prognostic analysis revealed CCNBI, CDK9, and PLCG1 associated with poor prognosis. Conclusion: PKCε regulates genes that are responsible for cancer progression. Therefore, targeting PKCε in Prostate cancer may serve as an important regulatory effect and may improve the prognosis of the disease.

Inhibitory Effect of PPARδ Agonist GW501516 on Proliferation of Hypoxia-induced Pulmonary Arterial Smooth Muscle Cells by Regulating the mTOR Pathway.

This study aimed to investigate the effects of the peroxisome proliferator-activated receptor δ (PPARδ) agonist GW501516 on the proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by hypoxia, in order to search for new drugs for the treatment and prevention of pulmonary vascular remodeling. PASMCs were incubated with different concentrations of GW501516 (10, 30, 100 nmol/L) under the hypoxic condition. The proliferation was determined by a CCK-8 assay. The cell cycle progression was analyzed by flow cytometry. The expression of PPARδ, S phase kinase-associated protein 2 (Skp2), and cell cycle-dependent kinase inhibitor p27 was detected by Western blotting. Then PASMCs were treated with 100 nmol/ L GW501516, 100 nmol/L mammalian target of rapamycin (mTOR) inhibitor rapamycin and/or 2 µmol/L mTOR activator MHY1485 to explore the molecular mechanisms by which GW501516 reduces the proliferation of PASMCs. The presented data demonstrated that hypoxia reduced the expression of PPARδ in an oxygen concentration- and time-dependent manner, and GW501516 decreased the proliferation of PASMCs induced by hypoxia by blocking the progression through the G0/G1 to S phase of the cell cycle. In accordance with these findings, GW501516 downregulated Skp2 and upregulated p27 in hypoxia-exposed PASMCs. Further experiments showed that rapamycin had similar effects as GW501516 in inhibiting cell proliferation, arresting the cell cycle, regulating the expression of Skp2 and p27, and inactivating mTOR in hypoxia-exposed PASMCs. Moreover, MHY1485 reversed all the beneficial effects of GW501516 on hypoxia-stimulated PASMCs. GW501516 inhibited the proliferation of PASMCs induced by hypoxia through blocking the mTOR/Skp2/p27 signaling pathway.

Imidazole-4-N-acetamide Derivatives as a Novel Scaffold for Selective Targeting of Cyclin Dependent Kinases.

The rational design of cyclin-dependent protein kinase (CDK) inhibitors presumes the development of approaches for accurate prediction of selectivity and the activity of small molecular weight anticancer drug candidates. Aiming at attenuation of general toxicity of low selectivity compounds, we herein explored the new chemotype of imidazole-4-N-acetamide substituted derivatives of the pan-CDK inhibitor PHA-793887. Newly synthesized compounds 1-4 containing an aliphatic methyl group or aromatic radicals at the periphery of the scaffold were analyzed for the prediction of relative free energies of binding to CDK1, -2, -5, and -9 using a protocol based on non-equilibrium (NEQ) thermodynamics. This methodology allows for the demonstration of a good correlation between the calculated parameters of interaction of 1-4 with individual targets and the values of inhibitory potencies in in vitro kinase assays. We provide evidence in support of NEQ thermodynamics as a time sparing, precise, and productive approach for generating chemical inhibitors of clinically relevant anticancer targets.

Cell cycle-dependent kinase inhibitor GhKRP6, a direct target of GhBES1.4, participates in BR regulation of cell expansion in cotton.

The steroidal hormone brassinosteroid (BR) has been shown to positively regulate cell expansion in plants. However, the specific mechanism by which BR controls this process has not been fully understood. In this study, RNA-seq and DAP-seq analysis of GhBES1.4 (a core transcription factor in BR signaling) were used to identify a cotton cell cycle-dependent kinase inhibitor called GhKRP6. The study found that GhKRP6 was significantly induced by the BR hormone and that GhBES1.4 directly promoted the expression of GhKRP6 by binding to the CACGTG motif in its promoter region. GhKRP6-silenced cotton plants had smaller leaves with more cells and reduced cell size. Furthermore, endoreduplication was inhibited, which affected cell expansion and ultimately decreased fiber length and seed size in GhKRP6-silenced plants compared with the control. The KEGG enrichment results of control and VIGS-GhKRP6 plants revealed differential expression of genes related to cell wall biosynthesis, MAPK, and plant hormone transduction pathways - all of which are related to cell expansion. Additionally, some cyclin-dependent kinase (CDK) genes were upregulated in the plants with silenced GhKRP6. Our study also found that GhKRP6 could interact directly with a cell cycle-dependent kinase called GhCDKG. Taken together, these results suggest that BR signaling influences cell expansion by directly modulating the expression of cell cycle-dependent kinase inhibitor GhKRP6 via GhBES1.4.

Acrylamide induces human chondrocyte cell death by initiating autophagy‑dependent ferroptosis.

Acrylamide (ACR) is formed during heat treatment of foodstuffs and ACR may serve as a probable malignant neoplastic disease agent in all organs and tissues of the human body. However, it is unknown if ACR is associated with ankylosing spondylitis (AS) pathogenesis. Cell viability and proliferation were determined using CCK-8 assay and EdU staining. Flow cytometry was used to determine cell death and cell cycle arrest. Intracellular lipid reactive oxygen species, Fe2+ and mitochondrial membrane potential (MMP) were analyzed using a C11-BODIPY581/591 fluorescent probe, FerroOrange staining and a JC-1 MMP Assay kit, respectively. The present study showed that ACR decreased chondrocyte cell viability in a dose-dependent manner and that ACR significantly promoted chondrocyte senescence. ACR also elevated the expression of cell cycle arrest-associated proteins, including p53, cyclin-dependent kinase inhibitor 1 and cyclin-dependent kinase inhibitor protein, in human chondrocytes. Similarly, DNA damage was also enhanced following ACR treatment in chondrocytes. In addition, the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) and the autophagy inhibitor 3-methyladenine abolished ACR-induced cell death in chondrocytes. ACR was shown to activate autophagic flux and induce mitochondrial dysfunction by increasing the MMP. Western blot analysis of ferroptosis-related proteins demonstrated that ACR decreased the expression of glutathione peroxidase 4, solute carrier family 7 member 11, transferrin receptor protein 1 and ferritin heavy chain 1 in chondrocytes whereas Fer-1 abolished these effects. ACR treatment significantly elevated the phosphorylation levels of AMP-activated protein kinase (AMPK) and serine/threonine-protein kinase ULK1 in human chondrocytes. Notably, the effect of ACR was diminished by knockdown of AMPK, as evidenced by reduced lipid reactive oxygen species accumulation and Fe2+ levels. Hence, ACR inhibited cell proliferation and contributed to cell death by inducing autophagy-dependent ferroptosis while promoting autophagy by activating AMPK-ULK1-mTOR signaling in human chondrocytes. It was hypothesized that the presence of ACR in foodstuffs may increase the risk of AS and that decreasing ACR in food products is of importance.

Abstract 1422: Fibroblast growth factor receptor-1 is a novel therapeutic target in mantle cell Lymphoma

Abstract Cell cycle dysregulation and significant enrichment of E2F1 target genes are hallmarks of MCL, and the inability to directly target E2F1-dependent processes is a clinical hindrance. Despite several treatment options, mantle cell lymphoma is associated with poor clinical outcomes and the development of resistance. We identified Fibroblast Growth Factor Receptor-1 is upregulated in relapsed mantle cell lymphoma patients and high FGFR-1 expression in MCL correlates with poor overall and progression-free survival. Genetic ablation of FGFR1 in MCL cells induced cell cycle arrest, and cell death in-vitro, inhibited tumor progression, and improved overall survival in-vivo. Functionally, FGFR1 loss upregulates the expression of the cell-cycle dependent Kinase inhibitor 1C (CDKN1C) through epigenetic repression via EZH2. CDKN1C binds to E2F1 and regulates the transactivation of its target genes, including CDK1. CDK1 further stabilizes MYC and positively regulates the expression of EZH2, activating the feed-forward loop to promote cell survival. Conversely, losing FGFR1 disrupts this feed-forward loop in malignant cells. This is the first report establishing FGFR1 as a novel therapeutic target and providing a rationale to target FGFR1 to treat Mantle cell lymphoma and disrupt the feed-forward loops contributing to the survival of malignant cells. Citation Format: Anuvrat Sircar, Satishkumar Singh, Ken H. Young, Narendranath Epperla, Lalit Sehgal. Fibroblast growth factor receptor-1 is a novel therapeutic target in mantle cell Lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1422.

Infectious Recombinant Senecavirus A Expressing p16INK4A Protein.

Senecavirus A (SVA) is an oncolytic RNA virus, and it is the ideal oncolytic virus that can be genetically engineered for editing. However, there has not been much exploration into creating SVA viruses that carry antitumor genes to increase their oncolytic potential. The construction of SVA viruses carrying antitumor genes that enhance oncolytic potential has not been fully explored. In this study, a recombinant SVA-CH-01-2015 virus (p15A-SVA-clone) expressing the human p16INK4A protein, also known as cell cycle-dependent protein kinase inhibitor 2A (CDKN2A), was successfully rescued and characterized. The recombinant virus, called SVA-p16, exhibited similar viral replication kinetics to the parent virus, was genetically stable, and demonstrated enhanced antitumor effects in Ishikawa cells. Additionally, another recombinant SVA virus carrying a reporter gene (iLOV), SVA-iLOV, was constructed and identified using the same construction method as an auxiliary validation. Collectively, this study successfully created a new recombinant virus, SVA-p16, that showed increased antitumor effects and could serve as a model for further exploring the antitumor potential of SVA as an oncolytic virus.

Transcriptional Reprogramming Regulates Tumor Cell Survival in Response to Ionizing Radiation: a Role of p53.

Senexin B, a non-toxic selective inhibitor of cyclin-dependent protein kinases 8 and 19 (CDK8 and CDK19), in combination with γ-photon irradiation in doses of 2-10 Gy increased the death of colon adenocarcinoma cell line HCT116 (intact p53) in a logarithmically growing culture, which was accompanied by the prevention of cell cycle arrest and a decrease of "senescence" phenotype. The effect of senexin B in cells with intact p53 is similar to that of Tp53 gene knockout: irradiated HCT116p53KO cells passed through the interphase and died independently of senexin B. The inhibitor reduced the ability of cells to colony formation in response to irradiation; p53 status did not affect the effectiveness of the combination of radiation and senexin B. Thus, the CDK8/19 inhibitor senexin B increased cell sensitivity to radiotherapy by mechanisms dependent and independent of p53 status.

Platycodin D confers oxaliplatin Resistance in Colorectal Cancer by activating the LATS2/YAP1 axis of the hippo signaling pathway.

Oxaliplatin-based therapy is used as a first-line drug to treat metastatic colorectal cancer. However, long-term and repeated drug treatment resulted in drug resistance and the failure of chemotherapy. Various natural compounds were previously reported to act as chemosensitizers to reverse drug resistance. In this study, we found that platycodin D (PD), a saponin found in Platycodon grandiflorum, inhibited LoVo and OR-LoVo cells proliferation, invasion, and migration ability. Our results indicated that combined treatment of oxaliplatin with PD dramatically reduced the cellular proliferation in both LoVo and OR-LoVo cells. Furthermore, treatment with PD dose-dependently decreased LATS2/YAP1 hippo signaling and survival marker p-AKT expression, as well as increased cyclin-dependent kinase inhibitor proteins such as p21 and p27 expression. Importantly, PD activates and promotes YAP1 degradation through the ubiquitination and proteasome pathway. The nuclear transactivation of YAP was significantly reduced under PD treatment, leading to transcriptional inhibition of the downstream genes regulating cell proliferation, pro-survival, and metastasis. In conclusion, our results showed that PD is suitable as a promising agent for overcoming oxaliplatin-resistant colorectal cancer.

Suppression of intrahepatic cholangiocarcinoma cell growth by SKI via upregulation of the CDK inhibitor p21.

Cholangiocarcinoma (CC) has a poor prognosis and different driver genes depending on the site of onset. Intrahepatic CC is the second-most common liver cancer after hepatocellular carcinoma, and novel therapeutic targets are urgently needed. The present study was conducted to identify novel therapeutic targets by exploring differentially regulated genes in human CC. MicroRNA (miRNA) and mRNA microarrays were performed using tissue and serum samples obtained from 24 surgically resected hepatobiliary tumor cases, including 10 CC cases. We conducted principal component analysis to identify differentially expressed miRNA, leading to the identification of miRNA-3648 as a differentially expressed miRNA. We used an in silico screening approach to identify its target mRNA, the tumor suppressor Sloan Kettering Institute (SKI). SKI protein expression was decreased in human CC cells overexpressing miRNA-3648, endogenous SKI protein expression was decreased in human CC tumor tissues, and endogenous SKI mRNA expression was suppressed in human CC cells characterized by rapid growth. SKI-overexpressing OZ cells (human intrahepatic CC cells) showed upregulation of cyclin-dependent kinase inhibitor p21 mRNA and protein expression and suppressed cell proliferation. Nuclear expression of CDT1 (chromatin licensing and DNA replication factor 1), which is required for the G1/S transition, was suppressed in SKI-overexpressing OZ cells. SKI knockdown resulted in the opposite effects. Transgenic p21-luciferase was activated in SKI-overexpressing OZ cells. These data indicate SKI involvement in p21 transcription and that SKI-p21 signaling causes cell cycle arrest in G1, suppressing intrahepatic CC cell growth. Therefore, SKI may be a potential therapeutic target for intrahepatic CC.

In vitro pharmacodynamic studies of novel class Ⅰ and Ⅱb selective histone deacetylase inhibitor purinostat mesylate in the treatment of diffuse large B-cell lymphoma and its mechanism

Objective: To investigate the in vitro inhibitory activity of a novel class Ⅰ and Ⅱb selective histone deacetylase (HDAC) inhibitor, purinostat mesylate (PM) , in diffuse large B-cell lymphoma and its mechanism. Methods: The 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide method was used to detect the effect of PM on cell proliferation. The effects of PM on cell cycle and apoptosis were detected by flow cytometry. The acetylation levels of HDAC substrate, cell cycle protein, apoptosis-related protein, and oncogene protein expression were detected by Western blot. Results: PM significantly inhibited the proliferation of lymphoma SUDHL-4 and SUDHL-6 cells and increased the acetylation levels of HDAC substrates H3, H4, and α-tubulin. In cell cycle experiments, PM induced G(0)/G(1) phase arrest in SUDHL-4 and SUDHL-6 cells. Western blot experiment showed that PM could significantly downregulate the expression of cyclin-dependent kinases Cdk2, Cdk4, Cdk6, cyclin D1, and cyclin E and upregulate the expression of CDK inhibitor protein p21. In the apoptosis experiment, PM could induce the apoptosis of SUDHL-4 and SUDHL-6 cells. Western blot experiment demonstrated that PM promoted endogenous apoptosis by activating caspase-3 kinase and affecting antiapoptotic protein Bcl-2. In addition, PM could downregulate the expression of oncogene marker proteins MYC, IKZF1, and IKZF3. Conclusion: PM has an efficient biological activity in vitro for diffuse large B-cell lymphoma, including double-hit lymphoma, and provides valuable experimental evidence for PM in clinical treatment.

CDK inhibitor Palbociclib targets STING to alleviate autoinflammation.

Aberrant activation of stimulator of interferon genes (STING) is tightly associated with multiple types of disease, including cancer, infection, and autoimmune diseases. However, the development of STING modulators for the therapy of STING-related diseases is still an unmet clinical need. We employed a high-throughput screening approach based on the interaction of small-molecule chemical compounds with recombinant STING protein to identify functional STING modulators. Intriguingly, the cyclin-dependent protein kinase (CDK) inhibitor Palbociclib was found to directly bind STING and inhibit its activation in both mouse and human cells. Mechanistically, Palbociclib targets Y167 of STING to block its dimerization, its binding with cyclic dinucleotides, and its trafficking. Importantly, Palbociclib alleviates autoimmune disease features induced by dextran sulphate sodium or genetic ablation of three prime repair exonuclease 1 (Trex1) in mice in a STING-dependent manner. Our work identifies Palbociclib as a novel pharmacological inhibitor of STING that abrogates its homodimerization and provides a basis for the fast repurposing of this Food and Drug Administration-approved drug for the therapy of autoinflammatory diseases.

Isolation, crystal structure, absolute configuration and molecular docking of butyrolactone I as a potential inhibitor of topoisomerase II

Butyrolactone I is a natural butenolide that has been isolated from the culture broth of the thermophilic fungus Aspergillus terreus TM8. Its structure was determined by HR-ESI-MS as well as NMR spectroscopic data. The crystal structure and absolute configuration of butyrolactone I are reported herein for the first time based on single crystal X-ray diffraction. Butyrolactone I is known as a highly selective inhibitor of cyclin-dependent protein kinases which inhibits cell cycle progression at the G1/S and G2/M transitions. Through this study, we investigate the action of butyrolactone I against the human topoisomerase II (topo II) and vascular endothelial growth factor receptor2 (VEGFR2) kinase. The molecular docking results introduced butyrolactone I either as a catalytic inhibitor against topo IIα or a poison to topo IIβ while the first mechanism is the most likely to take place. Contrarily to topo II, butyrolactone I displayed a low affinity toward VEGFR2 kinase. In the light of the molecular docking investigation, butyrolactone I, in synchronizing to a catalytic inhibitor and poison control, was subjected to the in vitro topo IIα relaxation assay. The results revealed the capability of butyrolactone I to suppress the relaxation of the supercoiled DNA plasmid in a concentration-dependent manner, with IC50 value of 6.64 μM. Interestingly, this IC50 was more comparable to the catalytic inhibitor (staurosporine) rather than the poison one (doxorubicin).

AB1, a novel protein targeting TP53 mutated GI tumors.

96 Background: The tumor suppressor gene TP53 is one of the most frequently deleted or mutated genes in gastrointestinal cancers. Normal p53 regulates several important proteins that control cell cycle, cell death, DNA damage/repair, stemness, differentiation and other key cellular functions. If the TP53 gene is damaged, tumor suppression is severely compromised. On the other hand, and downstream of p53, p21 a potent cyclin-dependent kinase inhibitor (CKI) protein binds and inhibitsthe activity of cyclin - CDK2, - CDK1, and - CDK4/6, thus functioning as a regulator ofcell cycle progression at G 1 and S phase. It can act as de facto p53 repair/ replacement mechanism. We have thus hypothesised that, if we were able to deliver wild type p21 into all p53 mutated cancer cells, it would have a possible therapeutic effect. Methods: We have constructed recombinantly a new fusion protein, named AB1, composed of a cell penetrating protein (antennapedia) ANTP and wild type p21 and tested it in in vitro and in vivo preclinical models prior to clinical studies. AB1 could also be constructed semi-synthetically by conjugating recombinant ANTP chemically to p21 protein. Results: AB1 penetrated and killed p53 mutated cancer cells but did not kill cells that did not have p53 mutations AB1 penetrated but did not kill p53- or p21- wild-type cells. AB1 was not immunogenic in normal New Zealand White rabbits. AB1 was more cytotoxic when administered with conventionally-used chemotherapeutic agents. Conclusions: We have generated a selectively cytotoxic fusion protein against p53 mutated GI cancers which is effective when used as a single agent but more so when used in combination with chemotherapy. The phaseI/II clinical trial will include eligible patients who have p53 mutated GI cancers