Cell cycle plays a crucial role in cell development. Cell cycle progression is mainly regulated by cyclin dependent kinase (CDK), cyclin and endogenous CDK inhibitor (CKI). Among these, CDK is the main cell cycle regulator, binding to cyclin to form the cyclin-CDK complex, which phosphorylates hundreds of substrates and regulates interphase and mitotic progression. Abnormal activity of various cell cycle proteins can cause uncontrolled proliferation of cancer cells, which leads to cancer development. Therefore, understanding the changes in CDK activity, cyclin-CDK assembly and the role of CDK inhibitors will help to understand the underlying regulatory processes in cell cycle progression, as well as provide a basis for the treatment of cancer and disease and the development of CDK inhibitor-based therapeutic agents. This review focuses on the key events of CDK activation or inactivation, and summarizes the regulatory processes of cyclin-CDK at specific times and locations, as well as the progress of research on relevant CDK inhibitor therapeutics in cancer and disease. The review concludes with a brief description of the current challenges of the cell cycle process, with the aim to provide scientific references and new ideas for further research on cell cycle process.
Cyclin-Dependent Kinases/metabolism* ; Cyclins/metabolism* ; Protein Serine-Threonine Kinases ; Cell Cycle Proteins/metabolism* ; Cell Cycle/physiology* ; Cyclin-Dependent Kinase 2

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These f indings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.
Mesenchymal Stem Cells/physiology* ; Cellular Senescence ; Homeostasis ; Cell Cycle Proteins/metabolism* ; Adaptor Proteins, Signal Transducing/metabolism* ; Mitochondria/metabolism* ; Electron Transport Complex III/metabolism* ; Humans ; Cells, Cultured

BACKGROUNDBrain acid soluble protein 1 (BASP1) is identified as a novel potential tumor suppressor in several cancers. However, its role in thyroid cancer has not been investigated yet. In the present study, the antitumor activities of BASP1 against the growth and migration of thyroid cancer cells were evaluated.

METHODSBASP1 expression in thyroid cancer tissues and normal tissues were examined by immunohistochemical staining and the association between its expression and prognosis was analyzed. pcDNA-BASP1 carrying full length of BASP1 cDNA was constructed to restore the expression of BASP1 in thyroid cancer cell lines (BHT-101 and KMH-2). The cell proliferation in vitro and in vivo was evaluated by WST-1 assay and xenograft tumor models, respectively. Cell cycle distribution after transfection was analyzed using flow cytometry. Cell apoptosis after transfection was examined by annexin V/propidium iodide assay. The migration was examined using transwell assay.

RESULTSBASP1 expression was abundant in normal tissues while it is significantly decreased in cancer tissues (P = 0.000). pcDNA-BASP1 restored the expression of BASP1 and significantly inhibited the growth of BHT-101 and KMH-2 cells as well as xenograft tumors in nude mice (P = 0.000). pcDNA-BASP1 induced G1 arrest and apoptosis in BHT-101 and KMH-2 cells. In addition, pcDNA-BASP1 significantly inhibited the cell migration.

CONCLUSIONSDownregulation of BASP1 expression may play a role in the tumorigenesis of thyroid cancer. Restoration of BASP1 expression exerted extensive antitumor activities against growth and migration of thyroid cancer cells, which suggested that BASP1 gene might act as a potential therapeutic agent for the treatment of thyroid cancer.

Aged ; Animals ; Apoptosis ; genetics ; physiology ; Calmodulin-Binding Proteins ; genetics ; metabolism ; Cell Cycle ; genetics ; physiology ; Cell Line, Tumor ; Cell Movement ; genetics ; physiology ; Cell Proliferation ; genetics ; physiology ; Cytoskeletal Proteins ; genetics ; metabolism ; Female ; Gene Expression Regulation, Neoplastic ; genetics ; physiology ; Humans ; Male ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mice, Nude ; Middle Aged ; Nerve Tissue Proteins ; genetics ; metabolism ; Repressor Proteins ; genetics ; metabolism ; Thyroid Neoplasms ; metabolism ; pathology ; Xenograft Model Antitumor Assays

BACKGROUNDRetinal degenerative diseases are the leading causes of blindness in developed world. Retinal progenitor cells (RPCs) play a key role in retina restoration. Triamcinolone acetonide (TA) is widely used for the treatment of retinal degenerative diseases. In this study, we investigated the role of TA on RPCs in hypoxia condition.

METHODSRPCs were primary cultured and identified by immunofluorescence staining. Cells were cultured under normoxia, hypoxia 6 h, and hypoxia 6 h with TA treatment conditions. For the TA treatment groups, after being cultured under hypoxia condition for 6 h, RPCs were treated with different concentrations of TA for 48-72 h. Cell viability was measured by cell counting kit-8 (CCK-8) assay. Cell cycle was detected by flow cytometry. Western blotting was employed to examine the expression of cyclin D1, Akt, p-Akt, nuclear factor (NF)-κB p65, and caspase-3.

RESULTSCCK-8 assays indicated that the viability of RPCs treated with 0.01 mg/ml TA in hypoxia group was improved after 48 h, comparing with control group (P < 0.05). After 72 h, the cell viability was enhanced in both 0.01 mg/ml and 0.02 mg/ml TA groups compared with control group (all P < 0.05). Flow cytometry revealed that there were more cells in S-phase in hypoxia 6 h group than in normoxia control group (P < 0.05). RPCs in S and G2/M phases decreased in groups given TA, comparing with other groups (all P < 0.05). There was no significant difference in the total Akt protein expression among different groups, whereas upregulation of p-Akt and NF-κB p65 protein expression and downregulation of caspase-3 and cyclin D1 protein expression were observed in 0.01 mg/ml TA group, comparing with hypoxia 6 h group and control group (all P < 0.05).

CONCLUSIONLow-dose TA has anti-apoptosis effect on RPCs while it has no stimulatory effect on cell proliferation.

Animals ; Apoptosis ; drug effects ; physiology ; Caspase 3 ; metabolism ; Cell Cycle ; drug effects ; physiology ; Cell Hypoxia ; drug effects ; physiology ; Cell Proliferation ; drug effects ; physiology ; Cell Survival ; drug effects ; physiology ; Cells, Cultured ; Cyclin D1 ; metabolism ; NF-kappa B ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Sprague-Dawley ; Retina ; cytology ; Stem Cells ; cytology ; drug effects ; Triamcinolone Acetonide ; pharmacology

BACKGROUNDThe Notch-regulated ankyrin repeat protein (NRARP) is recently found to promote proliferation of breast cancer cells. The role of NRARP in carcinogenesis deserves extensive investigations. This study attempted to investigate the expression of NRARP in thyroid cancer tissues and assess the influence of NRARP on cell proliferation, apoptosis, cell cycle, and invasion in thyroid cancer.

METHODSThirty-four cases with thyroid cancer were collected from the Department of General Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine between 2011 and 2012. Immunohistochemistry was used to detect the level of NRARP in cancer tissues. Lentivirus carrying NRARP-shRNA (Lenti-NRARP-shRNA) was applied to down-regulate NRARP expression. Cell viability was tested after treatment with Lenti-NRARP-shRNA using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis and cell cycle distribution were determined by flow cytometry. Cell invasion was tested using Transwell invasion assay. In addition, expressions of several cell cycle-associated and apoptosis-associated proteins were examined using Western blotting after transfection. Student's t-test, one-way analysis of variance (ANOVA), or Kaplan-Meier were used to analyze the differences between two group or three groups.

RESULTSNRARP was highly expressed in thyroid cancer tissues. Lenti-NRARP-shRNA showed significantly inhibitory activities against cell growth at a multiplicity of infection of 10 or higher (P < 0.05). Lenti-NRARP-shRNA-induced G1 arrest (BHT101: 72.57% ± 5.32%; 8305C: 75.45% ± 5.26%) by promoting p21 expression, induced apoptosis by promoting bax expression and suppressing bcl-2 expression, and inhibited cell invasion by suppressing matrix metalloproteinase-9 expression.

CONCLUSIONDownregulation of NRARP expression exerts significant antitumor activities against cell growth and invasion of thyroid cancer, that suggests a potential role of NRARP in thyroid cancer targeted therapy.

Adult ; Aged ; Animals ; Apoptosis ; genetics ; physiology ; Cell Cycle ; genetics ; physiology ; Cell Line, Tumor ; Cell Proliferation ; genetics ; physiology ; Cell Survival ; genetics ; physiology ; Female ; Humans ; In Vitro Techniques ; Kaplan-Meier Estimate ; Male ; Mice ; Mice, Nude ; Middle Aged ; Neoplasm Proteins ; genetics ; metabolism ; Proteins ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Thyroid Neoplasms ; genetics ; metabolism ; mortality ; pathology

The BCCIP (BRCA2- and CDKN1A-interacting protein) is an important cofactor for BRCA2 in tumor suppression. Although the low expression of BCCIP is observed in multiple clinically diagnosed primary tumor tissues such as ovarian cancer, renal cell carcinoma and colorectal carcinoma, the mechanism of how BCCIP is regulated in cells is still unclear. The human INO80/YY1 chromatin remodeling complex composed of 15 subunits catalyzes ATP-dependent sliding of nucleosomes along DNA. Here, we first report that BCCIP is a novel target gene of the INO80/YY1 complex by presenting a series of experimental evidence. Gene expression studies combined with siRNA knockdown data locked candidate genes including BCCIP of the INO80/YY1 complex. Silencing or over-expressing the subunits of the INO80/YY1 complex regulates the expression level of BCCIP both in mRNA and proteins in cells. Also, the functions of INO80/YY1 complex in regulating the transactivation of BCCIP were confirmed by luciferase reporter assays. Chromatin immunoprecipitation (ChIP) experiments clarify the enrichment of INO80 and YY1 at +0.17 kb downstream of the BCCIP transcriptional start site. However, this enrichment is significantly inhibited by either knocking down INO80 or YY1, suggesting the existence of both INO80 and YY1 is required for recruiting the INO80/YY1 complex to BCCIP promoter region. Our findings strongly indicate that BCCIP is a potential target gene of the INO80/YY1 complex.
Calcium-Binding Proteins ; genetics ; metabolism ; Cell Cycle Proteins ; genetics ; metabolism ; Chromatin Assembly and Disassembly ; physiology ; DNA Helicases ; genetics ; metabolism ; HeLa Cells ; Humans ; Multiprotein Complexes ; genetics ; metabolism ; Nuclear Proteins ; genetics ; metabolism ; Promoter Regions, Genetic ; physiology ; Transcription, Genetic ; physiology ; YY1 Transcription Factor ; genetics ; metabolism

Animals ; Cadherins ; metabolism ; Cell Cycle Proteins ; genetics ; metabolism ; Cell Differentiation ; Cell Line, Tumor ; Early Growth Response Protein 1 ; genetics ; metabolism ; Estradiol ; physiology ; Eukaryotic Initiation Factor-3 ; metabolism ; Genes, Tumor Suppressor ; physiology ; HSP90 Heat-Shock Proteins ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Iron ; metabolism ; Neoplasms ; metabolism ; pathology

Animals ; Apoptosis ; Cell Cycle ; Cell Movement ; Cell Proliferation ; Connexin 43 ; genetics ; metabolism ; Down-Regulation ; Gap Junctions ; metabolism ; physiology ; Humans ; Neoplasms ; metabolism ; pathology ; Tumor Suppressor Proteins ; genetics ; metabolism

OBJECTIVETo study the influence of hepatitis B virus (HBV) replication and expressions of different viral genes on CDC37 level in hepatocytes.

METHODSWe amplified and cloned 6 HBV genes (P, preS1, preS2, S, C and X) into pCMV expression vectors, which were transfected in Huh7 and HepG2 hepatoma cell lines, and CDC37 expression level in the cells was detected using Western blotting. Wealso cloned the promoter sequence of CDC37 into pGL3 vector, and co-transfected pGL3 with pCMV recombinant plasmids into Huh7 and HepG2 cells and the fluorescent signals were detected. To study the influence of HBV replication on CDC37 expression, we constructed 1.28-copy overlength genomes of HBV genotypes B, C, D and CD recombinant. The overlength HBV genomes were transformed into Adeasier-1 cells for recombination and into 293 cells for packaging. Huh7 and HepG2 cell lines infected with the packaged HBV recombinant adenoviruses were examined for CDC37 expression with Western blotting.

RESULTSWestern blotting showed that the expression of different HBV genes did not obviously affect the protein level of CDC37 in the hepatocytes. The protein expression of HBV genes had no effect on the activity of CDC37 promoter. Huh7 and HepG2 cells infected with 1.28-copy HBV replicon showed no significant changes in the expression level of CDC37.

CONCLUSIONHBV replication and its gene expression have no effect on the level of CDC37 in hepatocytes in vitro.

Adenoviridae ; Cell Cycle Proteins ; metabolism ; Chaperonins ; metabolism ; Gene Expression Regulation, Viral ; Genetic Vectors ; Hep G2 Cells ; Hepatitis B virus ; genetics ; physiology ; Hepatocytes ; virology ; Humans ; Transfection ; Virus Replication

BACKGROUNDMicroRNAs (miRNAs) contribute to tumorigenesis by acting as either oncogenes or tumor suppressor genes. In this study, we investigated the role of miR-145 in the pathogenesis of uveal melanoma.

METHODSExpression profiles of miRNAs in uveal melanoma were performed using Agilent miRNA array. Quantitative real-time polymerase chain reaction was used to screen the expression levels of miR-145 in normal uveal tissue, uveal melanoma tissue, and uveal melanoma cell lines. Lenti-virus expression system was used to construct MUM-2B and OCM-1 cell lines with stable overexpression of miR-145. Cell proliferation, cell cycle, and cell apoptosis of these miR-145 overexpression cell lines were examined by MTT assay and flow cytometry respectively. The target genes of miR-145 were predicted by bioinformatics and confirmed using a luciferase reporter assay. The expression of insulin-like growth factor-1 receptor (IGF-1R), insulin receptor substrate-1 (IRS-1) proteins was determined by Western blotting analysis. IRS-1 was knocked down in OCM-1 cells. TUNEL, BrdU, and flow cytometry assay were performed in IRS-1 knocked down OCM-1 cell lines to analyze its function.

RESULTSForty-seven miRNAs were up regulated in uveal melanoma and 61 were down regulated. miR-145 expression was significantly lower in uveal melanoma sample and the cell lines were compared with normal uveal sample. Overexpression of miR-145 suppressed cell proliferation by blocking the G1 phase entering S phase in uveal melanoma cells, and promoted uveal melanoma cell apoptosis. IRS-1 was identified as a potential target of miR-145 by dual luciferase reporter assay. Knocking down of IRS-1 had similar effect as overexpression of miR-145.

CONCLUSIONmiR-145 might act as a tumor suppressor in uveal melanoma, and downregulation of the target IRS-1 might be a potential mechanism.

Apoptosis ; genetics ; physiology ; Blotting, Western ; Cell Cycle ; genetics ; physiology ; Cell Line, Tumor ; Cell Proliferation ; genetics ; physiology ; Humans ; In Vitro Techniques ; Insulin Receptor Substrate Proteins ; genetics ; metabolism ; Melanoma ; genetics ; metabolism ; pathology ; MicroRNAs ; genetics ; metabolism ; Polymerase Chain Reaction ; Uveal Neoplasms ; genetics ; metabolism ; pathology