BACKGROUND: Angiogenesis is an important process in the development of tumor. PD 0332991, a cell cycle inhibitor, can specifically inhibit CD4/6 phosphorylation and cell cycle progression. In xeongraft mice models, PD 0332991 treated mice had significantly decreased angiogenesis and vascular density compared with the control group, but the mechanism remains unknown. The purpose of this study is to investigate the role and molecular mechanism of PD 0332991 on vascular endothelial cells. METHODS: EA.hy926 cells, a kind of vascular endothelial cell, were used as the research model. The effects of PD 0332991 on the activity and proliferation of EA.hy926 cells were detected by the MTT, EdU assays. Wound-healing assays and transwell assays were used to determine the effects of PD 0332991 on the mobility of EA.hy926. The influence of PD 0332991 on cell cycle and apoptosis of endothelial cells was tested by flow cytometry, and the Western blot was applied to observe the expression of cell cycle related proteins in EA.hy926 cells treated by PD 0332991. RESULTS: PD 0332991 significantly inhibited the proliferation and mobility of EA.hy926 cells, caused cell cycle arrest and apoptosis. At the same time, PD 0332991 inhibited the expression of CDK4/6 and phosphorylation of Rb, and thus inhibited the cell cycle progression of EA.hy926 cells. CONCLUSIONS PD 0332991 can inhibit the proliferation and activity of endothelial cells and induces apoptosis.
Angiogenesis Inhibitors ; pharmacology ; Animals ; Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Cyclin-Dependent Kinase 4 ; genetics ; metabolism ; Cyclin-Dependent Kinase 6 ; genetics ; metabolism ; Endothelial Cells ; cytology ; drug effects ; metabolism ; Humans ; Lung Neoplasms ; drug therapy ; genetics ; metabolism ; physiopathology ; Mice ; Piperazines ; pharmacology ; Pyridines ; pharmacology

Senescence-associated secretory phenotype (SASP) is often a concomitant result of cell senescence, embodied by the enhanced function of secretion. The SASP factors secreted by senescent cells include cytokines, proteases and chemokines, etc, which can exert great influence on local as well as systemic environment and participate in the process of cell senescence, immunoregulation, angiogenesis, cell proliferation and tumor invasion, etc. Relative to the abundance of SASP models in human cells, the in vitro SASP model derived from mouse cells is scarce at present. Therefore, the study aimed to establish a mouse SASP model to facilitate the research in the field. With this objective, we treated the INK4a-deficient mouse NIH-3T3 cells and the wildtype mouse embryonic fibroblasts (MEF) respectively with mitomycin C (MMC), an anticarcinoma drug which could induce DNA damage. The occurring of cell senescence was evaluated by cell morphology, β-gal staining, integration ratio of EdU and Western blot. Quantitative RT-PCR and ELISA were used to detect the expression and secretion of SASP factors, respectively. The results showed that, 8 days after the treatment of NIH-3T3 cells with MMC (1 μg/mL) for 12 h or 24 h, the cells became enlarged and the ratios of β-gal-positive (blue-stained) cells significantly increased, up to 77.4% and 90.4%, respectively. Meanwhile, the expression of P21 protein increased and the integration ratios of EdU significantly decreased (P < 0.01). Quantitative RT-PCR detection showed that the mRNA levels of several SASP genes, including IL-6, TNF-α, IL-1α and IL-1β increased evidently. ELISA detection further observed an enhanced secretion of IL-6 (P < 0.01). On the contrary, although wildtype MEF could also be induced into senescence by MMC treatment for 12 h or 24 h, embodied by the enlarged cell volume, increased ratios of β-gal-positive cells (up to 71.7% and 80.2%, respectively) and enhanced expression of P21 protein, the secretion of IL-6 displayed no significant change. Our study indicated that, although MMC could induce senescence in both mouse NIH-3T3 cells and wildtype MEF, only senescent NIH-3T3 cells displayed the canonical SASP phenomena. Current study suggested that senescent NIH-3T3 cells might be an appropriate in vitro SASP model of mouse cells.
Animals ; Cell Proliferation ; Cellular Senescence ; drug effects ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Cytokines ; genetics ; metabolism ; DNA Damage ; Fibroblasts ; drug effects ; Interleukin-6 ; secretion ; Mice ; Mitomycin ; pharmacology ; NIH 3T3 Cells ; Phenotype

OBJECTIVETo investigate the expression of p16INK4a protein in breast cancer and analyze its clinical significance.

METHODSA total of 132 surgical specimens of primary breast cancer obtained between 2014 and 2015 were examined for expressions of ER, PR, CK5/6, Her-2 and p16INK4a proteins using immunohistochemistry.

RESULTSThe breast cancer samples were classified into 5 molecular subtypes, namely Luminal A (58 cases), Luminal B (32 cases), Her-2-positive (21 cases), basal-like (12 cases) and normal-like (9 cases) types. p16INK4a expression was negative in 7/132 (5.30%) cases, weakly positive in 15/132 (11.36%) cases, positive in 40/132 (30.30%) cases, and strongly positive in 70/132 (53.03%) cases. When categorizing negative and weakly positive cases into negative group and the positive and strongly positive cases into positive group, the total negative and positive expression rates of p16INK4a were 16.67% (22/132) and 83.33% (110/132) in the carcinoma tissues. Statistical analysis showed the expression intensity of p16INK4a differed significantly between the age groups (P<0.05) but was not significantly correlated with ER, PR, Her-2, molecular subtypes or metastasis of the tumors.

CONCLUSIONThe compensatory high expression of p16INK4a is the main mechanism of cell cycle deregulation in invasive breast cancer and can be an important specific molecular marker for invasive breast cancer.

Biomarkers, Tumor ; metabolism ; Breast Neoplasms ; classification ; diagnosis ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Female ; Humans ; Keratin-5 ; metabolism ; Keratin-6 ; metabolism ; Receptor, ErbB-2 ; metabolism ; Receptors, Estrogen ; metabolism ; Receptors, Progesterone ; metabolism

Osteosarcoma is the most common primary sarcoma of bone, and it is a leading cause of cancer death among adolescents and young adults. However, the molecular mechanism underlying osteosarcoma carcinogenesis remains poorly understood. Recently, cyclin-dependent kinase 6 (CDK6) was identified as an important oncogene. We found that CDK6 protein level, rather than CDK6 mRNA level, is much higher in osteosarcoma tissues than in normal adjacent tissues, which indicates a post-transcriptional mechanism involved in CDK6 regulation in osteosarcoma. MiRNAs are small non-coding RNAs that repress gene expression at the post-transcriptional level and have widely been shown to play important roles in many human cancers. In this study, we investigated the role of miR-29b as a novel regulator of CDK6 using bioinformatics methods. We demonstrated that CDK6 can be downregulated by miR-29b via binding to the 3'-UTR region in osteosarcoma cells. Furthermore, we identified an inverse correlation between miR-29b and CDK6 protein levels in osteosarcoma tissues. Finally, we examined the function of miR-29b-driven repression of CDK6 expression in osteosarcoma cells. The results revealed that miR-29b acts as a tumor suppressor of osteosarcoma by targeting CDK6 in the proliferation and migration processes. Taken together, our results highlight an important role for miR-29b in the regulation of CDK6 in osteosarcoma and may open new avenues for future osteosarcoma therapies.
3' Untranslated Regions ; Animals ; Base Sequence ; Bone Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Cyclin-Dependent Kinase 6 ; antagonists & inhibitors ; genetics ; metabolism ; Humans ; Mice ; MicroRNAs ; metabolism ; Osteosarcoma ; metabolism ; pathology ; RNA Interference ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; metabolism ; Rats ; Sequence Alignment ; Up-Regulation

OBJECTIVETo observe the effect of high-mobility group box-1 protein (HMGB1) on the proliferation of human nasopharyngeal carcinoma cell line C666-1 and explore the possible underlying mechanisms.

METHODSCultured C666-1 cells were treated with a siRNA targeting HMGB1 gene. The changes in the cell proliferation were detected by CCK8 analysis, the cell cycle distribution was assayed with flow cytometry, and the expressions of cyclin D1, CDK6 and related pathway proteins were detected with Western blotting. The effect of a HMGB1 plasmid carrying the reporter gene GFP on the proliferation of C666-1 cells was tested with CCK8 and EDU analysis.

RESULTSCompared with the control cells, the cells transfected with the siRNA targeting HMGB1 showed obviously suppressed cell proliferation (P<0.001), cell cycle arrest in G1 phase (P<0.001), and down-regulated expressions of cyclin D1, CDK6, STAT3 and P-STAT3. Overexpression of HMGB1 in cells transfected with the HMGB1 plasmid showed a significantly increased ratio of S phase cells (P<0.05) and obviously enhanced cell proliferation (P<0.001).

CONCLUSIONHMGB1 can promote the proliferation of human nasopharyngeal carcinoma cell line C666-1 by up- regulating cyclin D1 and CDK6 via the STAT3 signaling pathway.

Carcinoma ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Division ; Cell Line, Tumor ; Cell Proliferation ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 6 ; metabolism ; Down-Regulation ; HMGB1 Protein ; genetics ; Humans ; Nasopharyngeal Neoplasms ; pathology ; RNA, Small Interfering ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; Transfection ; Up-Regulation

OBJECTIVETo investigate the effects of bromodomain-containing protein 4 (BRD4) inhibitor GSK525762A on the proliferation and apoptosis of primary common B-cell acute lymphoblastic leukemia (common B-ALL) cells from adult patients, then to further explore the possible mechanisms.

METHODSPurified leukemia cells from 14 common B-ALL adult patients (4 Ph⁺ and 10 Ph⁻ cases) were obtained by flow cytometry sorting, and maintained in a mimic bone marrow microenvironment culture system for short-term culture. Leukemia cells were treated with various concentrations of GSK525762A. The inhibitory effects of BRD4 inhibitor on common B-ALL leukemia cells were measured by CCK-8 assay and the apoptosis of those cells was determined by AnnexinⅤ/7-AAD staining using flow cytometry. The transcripts of c-MYC, CDK6 and Bcl-2 were detected by quantitative RT-PCR, and the expression of c-MYC, CDK6 and Bcl-2 proteins were detected via Western blot.

RESULTSGSK525762A could inhibit the proliferation of leukemia cells from all 14 common B-ALL patients in a dose-dependent manner, the median value of IC50 was 256.25 (90.64-1 378.39)nmol/L. GSK525762A could promote cells apoptosis of B-ALL leukemia cells in a dose-dependent manner, the median apoptosis rates respectively were 45.17%(9.38%-70.91%), 66.02% (24.36%-96.34%) and 89.29% (39.29%-99.37%) after treated by 500, 1 000 and 2 500 nmol/L GSK525762A. GSK525762A has a similar effect on Ph⁺ ALL and Ph⁻ B-ALL, but the effect of proliferation inhibition and apoptosis enhancement on Ph+ B-ALL is weaker than that on Ph⁻ B-ALL. Compared with vehicle control group, the levels of c-MYC, Bcl-2 and CDK6 transcripts in leukemic cells were reduced after treatment for 24 h and 48 h by 1 000 nmol/L GSK525762A, and there are no significant differences in the downregulation of c-MYC and CDK6 mRNA between Ph⁺ and Ph⁻ B-ALL; however, the inhibitory effect on Bcl-2 transcription was weaker in Ph⁺ B-ALL cells than that in Ph⁻ B-ALL cells. Moreover, c-MYC, Bcl-2 and CDK6 protein levels decreased in GSK525762A treated group.

CONCLUSIONGSK525762A could strongly inhibit the proliferation of common B-ALL and trigger apoptosis; meanwhile it has certain effects against Ph⁺ ALL in vitro. The effect may be achieved by down-regulation of c-MYC, CDK6 and Bcl-2 expression.

Apoptosis ; Benzodiazepines ; pharmacology ; Cell Line, Tumor ; drug effects ; Cyclin-Dependent Kinase 6 ; metabolism ; Down-Regulation ; Flow Cytometry ; Humans ; Nuclear Proteins ; antagonists & inhibitors ; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Proto-Oncogene Proteins c-myc ; metabolism ; Transcription Factors ; antagonists & inhibitors

The elucidation of the molecular mechanisms underlying the differentiation and proliferation of human adipose tissue-derived stromal cells (hADSCs) represents a critical step in the development of hADSCs-based cellular therapies. To examine the role of the microRNA-103a-3p (miR-103a-3p) in hADSCs functions, miR-103a-3p mimics were transfected into hADSCs in order to overexpress miR-103a-3p. Osteogenic differentiation was induced for 14 days in an osetogenic differentiation medium and assessed by using an Alizarin Red S stain. The regulation of the expression of CDK6 (cyclin-dependent kinase 6), a predicted target of miR-103a-3p, was determined by western blot, real-time PCR and luciferase reporter assays. Overexpression of miR-103a-3p inhibited the proliferation and osteogenic differentiation of hADSCs. In addition, it downregulated protein and mRNA levels of predicted target of miR-103a-3p (CDK6 and DICER1). In contrast, inhibition of miR-103a-3p with 2'O methyl antisense RNA increased the proliferation and osteogenic differentiation of hADSCs. The luciferase reporter activity of the construct containing the miR-103a-3p target site within the CDK6 and DICER1 3'-untranslated regions was lower in miR-103a-3p-transfected hADSCs than in control miRNA-transfected hADSCs. RNA interference-mediated downregulation of CDK6 and DICER1 in hADSCs inhibited their proliferation and osteogenic differentiation. The results of the current study indicate that miR-103a-3p regulates the osteogenic differentiation of hADSCs and proliferation of hADSCs by direct targeting of CDK6 and DICER1 partly. These findings further elucidate the molecular mechanisms governing the differentiation and proliferation of hADSCs.
Adipose Tissue/*cytology ; Cell Differentiation ; *Cell Proliferation ; Cells, Cultured ; Cyclin-Dependent Kinase 6/genetics ; DEAD-box RNA Helicases/genetics ; *Gene Expression Regulation ; Humans ; MicroRNAs/genetics/*metabolism ; *Osteogenesis ; Ribonuclease III/genetics ; Stromal Cells/cytology/metabolism

OBJECTIVETo assess the effect of small interfering RNA (siRNA)-mediated suppression of CDK6 expression on the proliferation and cell cycles of nasopharyngeal carcinoma (NPC) cells in vitro.

METHODSQRT-PCR was used to examine the differential expression of CDK6 in 30 NPC tissues and 18 normal nasopharyngeal tissues. A siRNA targeting CDK6 was transfected in NPC CNE2 cells, and MTT assay and flow cytometry were used to analyze the changes in cell proliferation and cell cycle distribution. Western blotting was used to examine the expressions of the cell cycle-related factors.

RESULTSCompared with normal nasopharyngeal tissues, NPC tissues showed an increased expression of CDK6 mRNA. Knocking down CDK6 expression obviously inhibited tumor cell growth and cell cycle transition from G1 to S phase and caused reduced expressions of CDK4, CCND1, and E2F1 and enhanced expression of the tumor suppressor p21.

CONCLUSIONNPC tissues overexpress CDK6. Knocking down CDK6 expression inhibits the growth and cell cycle transition of NPC cells in vitro by inhibiting the expressions of CDK4, CCND1, and E2F1 and upregulating tumor suppressor p21 expression.

Carcinoma ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 4 ; metabolism ; Cyclin-Dependent Kinase 6 ; genetics ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; E2F1 Transcription Factor ; metabolism ; Gene Expression Regulation, Neoplastic ; Gene Knockdown Techniques ; Humans ; Nasopharyngeal Neoplasms ; pathology ; RNA, Messenger ; RNA, Small Interfering ; Transfection ; Up-Regulation

OBJECTIVETo explore the expression of CDK6 in nasopharyngeal carcinoma (NPC) and explore its clinical significance.

METHODSImmunohistochemistry was used to examine the differential expression of CDK6 protein in 101 NPC and 30 nasopharyngeal tissues, and the correlation of CDK6 expression with the clinical characteristics was analyzed in NPC cases.

RESULTSImmunohistochemistry demonstrated that CDK6 protein was a co-expressed factor in the cytoplasm and cell nuclei. CDK6 was expressed predominantly in the cytoplasm in nasopharyngeal tissues, but in NPC tissues, CDK6 was co-expressed predominantly in the cytoplasm and nuclei. Compared to the nasopharyngeal tissues, NPC tissues showed significantly up-regulated CDK6 expression (P=0.009) in positive correlation with tumor size (P=0.020) and clinical stages (P=0.0039).

CONCLUSIONSIncreased CDK6 protein expression is an unfavorable factor that promotes the development and progression of NPC.

Carcinoma ; Cell Nucleus ; Cyclin-Dependent Kinase 6 ; metabolism ; Cytoplasm ; Disease Progression ; Humans ; Immunohistochemistry ; Nasopharyngeal Neoplasms ; metabolism ; Up-Regulation

OBJECTIVETo investigate the expression of microRNA-218 (miR-218) and its role in hepatocellular carcinoma (HCC).

METHODSForty-six pairs of fresh surgical specimens of HCC and adjacent tissues were examined for miR-218 expression using qRT-PCR. A miR-218 mimic was transfected into HepG2 cells, and the cell viability and apoptosis were analyzed by MTT assay and flow cytometry, and the potential targets of miR-218 were detected by qRT-PCR and Western blotting.

RESULTSThe expressions of miR-218 in HCC tissues were significantly down-regulated compared to those in the adjacent tissues (P<0.05). Down-regulation of miR-218 was found to correlate significantly with the tumor size (>5 cm) and an advanced TNM stage (III+IV) (P<0.05). Ectopic expression of miR-218 in HepG2 cells resulted in suppressed cell proliferation and enhanced cell apoptosis as well as the down-regulation of Bmi-1 and CDK6 mRNA and protein expressions (P<0.05).

CONCLUSIONThe low-expression of miR-218 is correlated with malignant clinicopathological characteristics of HCC, and miR-218 may inhibit cell proliferation and promote cell apoptosis by down-regulating Bmi-1 and CDK6 in HCC.

Adult ; Aged ; Apoptosis ; Carcinoma, Hepatocellular ; genetics ; metabolism ; pathology ; Cell Proliferation ; Cyclin-Dependent Kinase 6 ; metabolism ; Female ; Hep G2 Cells ; Humans ; Liver Neoplasms ; genetics ; metabolism ; pathology ; Male ; MicroRNAs ; genetics ; metabolism ; Middle Aged ; Polycomb Repressive Complex 1 ; metabolism