OBJECTIVETo investigate the expression of human telomerase reverse transcripase (hTERT), cyclin D1 mRNA, p16(INK4), p21(WAF1) mRNA and p27(KIP1) protein in human ameloblastoma (ABs).

METHODSThe expression of hTERT, cyclin D1, p16(INK4), p21(WAF1) mRNA and p27(KIP1) protein in 54 cases of human ABs were detected by in situ hybridization or immunohistochemistry.

RESULTSThe positive cases of hTERT mRNA, cyclin D1 mRNA was 51, 23, respectively. The positive cases of p16(INK4), p21(WAF1) mRNA and p27(KIP1) protein was 17, 12, 9. Comparing with recurred and transformed malignantly, the expression of hTERT mRNA, cyclin D1 mRNA increased, and the expression of p16(INK4), p21(WAF1) mRNA and p27(KIP1) protein decreased or lost. The expression of hTERT mRNA and pl6(INK4), p21(WAF1) mRNA and p27(KIP1) protein in ABs had middle to high negative relation (r(k) = -0.587, r(k) = -0.652, r(k) = -0.783, P < 0.001).

CONCLUSIONThe hTERT mRNA expression in ABs is related to the reguation of pl6(INK4), p21(WAF1) mRNA and p27(KIP1) protein.

Ameloblastoma ; Cyclin D1 ; Cyclin-Dependent Kinase Inhibitor p21 ; Cyclin-Dependent Kinase Inhibitor p27 ; Cyclins ; Humans ; Immunohistochemistry ; RNA, Messenger ; Telomerase

BACKGROUNDBoth p16(INK4) and p21(Waf1) are tumor suppressors with similar biological functions in the regulation of cellular senescence. Previous reports showed that p16(INK4) could be activated by p21(Waf1) through transcriptional factor Sp1 in HeLa cells. This study was undertaken to determine the effects of p16(INK4) on the expression and functions of p21(Waf1).

METHODSHuman diploid fibroblast 2BS cells were stably transfected with sense (2BS/p16(INK4)), antisense p16(INK4) (2BS/asp16(INK4)) or empty vector (2BS/neo). Then they were assayed by reverse-transcription polymerase chain reaction (RT-PCR), fluorescence activated cell sorting (FACS) and Western blot.

RESULTS2BS/p16(INK4) cells exhibited cell cycle arrest in both G1 and G2/M phases. Endogenous p21(Waf1) protein levels increased twofold in the 2BS/p16(INK4) cells, but not decreased in the 2BS/asp16(INK4) cells. p21(Waf1) mRNA levels were not affected in neither 2BS/p16(INK4) nor 2BS/asp16(INK4) cells.

CONCLUSIONp16(INK4) may play an important role in the regulation of cellular senescence by modulating the p21(Waf1) protein level via the posttranscriptional mechanism.

Cell Cycle ; Cells, Cultured ; Cellular Senescence ; Cyclin-Dependent Kinase Inhibitor p16 ; physiology ; Cyclin-Dependent Kinase Inhibitor p21 ; physiology ; Fibroblasts ; metabolism ; Humans ; Transcription, Genetic

OBJECTIVE: To investigate the methylation status of CHD5 gene promoter in bone marrow from acute myeloid leukemia (AML) patients, and the underlying mechanism for initiating the pathogenesis of AML via p19/p53/p21 pathway. METHODS: Methylation status of the CHD5 gene promoter was detected by using methylation-specific polymerase chain reaction (MSPCR) in bone marrow from AML patients, and the iron-deficiency anemia (IDA) samples were served as control. The expression of CHD5, p19, p53 and p21 was determined by real-time quantitative reverse transcriptase PCR and Western blot. RESULTS: The methylation of CHD5 gene in bone marrow from AML patients increased significantly (39.06%) as compared with control group (6.67%). The methylation of CHD5 gene significantly correlated with chromosome karyotype differentiation (P＜0.01), but did not correlate with the patient's sex, age and clinical classification (P＞0.05). The mRNA expression of CHD5 gene in AML decreased, compared with control group, the mRNA and protein expression of p19, p53 and p21 in AML with CHD5 methylation promoter decreased. CONCLUSION The hypermeltylation of CHD5 gene promoter in AML patients can lead to decrease of CHD5, p19, p53 and p21 expression levels which may reduce the inhibitory effect on proliferation of leukemia cells through the regulation of p19, p53 and p21 pathway, thus promotes the occurence of AML.
Cyclin-Dependent Kinase Inhibitor p16 ; Cyclin-Dependent Kinase Inhibitor p21 ; DNA Helicases ; DNA Methylation ; Humans ; Leukemia, Myeloid, Acute ; Nerve Tissue Proteins ; Promoter Regions, Genetic ; Tumor Suppressor Protein p53

Aging is an independent risk factor for chronic diseases in the elderly, and understanding aging mechanisms is one of the keys to achieve early prevention and effective intervention for the diseases. Aging process is dynamic and systemic, making it difficult for mechanistic study. With recent advances in aging biomarkers and development of live-imaging technologies, more and more reporter mouse models have been generated, which can live monitor the aging process, and help investigate aging mechanisms at systemic level and develop intervention strategies. This review summarizes recent advances in live-imaging aging reporter mouse models based on widely used aging biomarkers (p16^Ink4a, p21^Waf1/Cip1, p53 and Glb1), and discusses their applications in aging research.
Humans ; Animals ; Mice ; Aged ; Aging ; Cyclin-Dependent Kinase Inhibitor p16/metabolism* ; Cyclin-Dependent Kinase Inhibitor p21/metabolism* ; Biomarkers ; Tumor Suppressor Protein p53

OBJECTIVE: To investigate the expression and clinicopathological significance of the cell cycle regulators cyclin E, cyclin D1, p21, p16 in laryngeal carcinogenesis tissus. METHOD: The expression of cell cycle regulators were detected by flow cytometry method in 23 cases of polyps of vocal cord, 69 cases of laryngeal precancerous change and 33 cases of laryngeal squamous cell carcinoma (LSCC), which tissue was paraffin embedded, sliced, dewaxed, and prepared into the cell suspension, then fluorescently labeled by cyclin E, cyclin D1, p21 and p16. RESULT: In polyps of vocal cord, laryngeal precancerous change and LSCC, The positive expression rate of cyclin E and cyclin D1 were respectively 13.04%, 20.29D, 42.420 and 26.09%, 43.48% and 93.94%. The positive expression rate of p16 and p21 were respectively 61.90%, 40.98%, 14.28% and 47.62%, 23.81%, 26.23%. Those showed the positive expression rate of cyclin D1, cyclin E gradually decreased from vocal cord polyps, laryngeal precancerous change to LSCC, (P < 0.05, P < 0.01), while the positive expression rate of p21 and p16 gradually decreased (P < 0.01). CONCLUSION The abnormal expression of cell cycle regulatory factors is the molecular events of laryngeal carcinoma. High expression of positive regulatory factors cyclin D1 and cyclin E, and low expression of negative regulatory factors p16 and p21, which showed the imbalance of multiple positive and negative regulatory factors related with cell cycle play an important role in the occurrence of laryngeal cancer.
Adult ; Cyclin D1 ; metabolism ; Cyclin E ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Female ; Flow Cytometry ; Humans ; Laryngeal Neoplasms ; metabolism ; pathology ; Male ; Middle Aged ; Oncogene Proteins ; metabolism

Cell Cycle ; Cyclin-Dependent Kinase Inhibitor p21 ; Cyclins ; analysis ; DNA Damage ; Dactinomycin ; pharmacology ; Humans ; Viral Nonstructural Proteins ; physiology

BACKGROUND/AIMS: The cyclin-dependent kinase inhibitors (CDKI) including p21, p27, and p57 of the kinase inhibitor protein (KIP) family are negative regulators of cell cycle progression and potentially act as tumor suppressor. Tumor behavior and growth are influenced by the extent of tumor cell proliferation. The aim of this study was to evaluate the expression of KIP family CDKI in gastric cancer tissue, and to examine the relationship between these expression and various clinicopathological parameters including tumor cell proliferation. METHODS: We conducted an immunohistochemical analysis of p21, p27, and p57 expression in 109 gastric cancer tissues. Tumor cell proliferation was assessed by immunohistochemistry with antibody against Ki-67. RESULTS: Negative expression of p21, p27, and p57 was demonstrated in 45.9%, 65.1%, and 57.8% of cancer tissues, respectively. Negative expression of p21 correlated with larger tumor size, poor differentiation, depth of invasion, lymph node metastasis and advanced TNM stage (p=0.048, 0.041, 0.001, 0.005, and 0.001 respectively). Negative expression of p21 correlated with poor survival (p=0.037). Tumors with negative p21 expression had higher Ki-67 expression than those with positive p21 expression (p=0.024). No significant correlation could be observed between status of p27 and p57 expression and various clinicopathological parameters including survival and tumor cell proliferation. CONCLUSIONS: These results suggest that negative expression of p21 may play an important role in carcinogenesis by stimulating tumor cell proliferation, and may help in predicting the prognosis of gastric cancer.
Adult ; Aged ; Cell Division ; Cyclin-Dependent Kinase Inhibitor Proteins/*metabolism ; Cyclin-Dependent Kinase Inhibitor p21/metabolism ; Cyclin-Dependent Kinase Inhibitor p27/metabolism ; Cyclin-Dependent Kinase Inhibitor p57/metabolism ; English Abstract ; Female ; Humans ; Male ; Middle Aged ; Stomach Neoplasms/*metabolism/mortality/pathology ; Survival Rate

BACKGROUND/AIMS: Eukaryotic cell cycle is regulated by signal transduction pathways mediated by complexes of cyclin dependent kinases (CDKs) and their partner cyclins, or by interaction with CDK inhibitors. Thioacetamide (TA) is a weak hepatocarcinogen causing several types of liver damage in a dose dependent manner and ultimately producing malignant transformation. We investigated alterations of expression of cell cycle regulators in the rat liver, involved in G1 entry and progression during TA administration. METHODS: We studied expression patterns of cyclin D1, CDK4, CDK6, p21(CIP1) and p16(INK4a) during daily intraperitoneal injection of low dose TA (50 mg/kg) till 7 day. We used western blot and immunohistochemistry for detection. RESULTS: Expression of cyclin D1, CDK4, CDK6 and p21(CIP1) increased from 6 hour and peaked at 2, 3 day, then decreased next 2 days, and re-increased at 6 day. Cytoplasmo-nuclear translocation of cyclin D1 and p21(CIP1) was evident within 1 day and prominent at 2 and 7 day. Expression of p16(INK4a) increased immediately after TA treatment and remarkably increased from 3 day and progressed till 7 day, showing cytoplasmic location, suggestive of inactive form. Most of in situ immunoreactions occurred at the centrilobular hepatocytes. Concomitant nuclear translocation of p21(CIP1) and cyclin D1, different with p16(INK4a) suggests that p21(CIP1) might be a transporter for nuclear translocation rather than cell cycle inhibitor. CONCLUSIONS: Daily administration of low dose TA makes cell cycle open and G1 progress, possibly due to cyclin D1, CDK4 and CDK 6, their transporter p21(CIP1), and inactive p16(INK4a), which occur at quiescent hepatocytes, not stem cells.
Animals ; Cell Cycle Proteins/*metabolism ; Cyclin D1/metabolism ; Cyclin-Dependent Kinase 4/metabolism ; Cyclin-Dependent Kinase 6/metabolism ; Cyclin-Dependent Kinase Inhibitor p16/metabolism ; Cyclin-Dependent Kinase Inhibitor p21/metabolism ; G1 Phase ; Immunohistochemistry ; Liver/*drug effects/enzymology/metabolism ; Liver Diseases/chemically induced/metabolism/pathology ; Male ; Rats ; Rats, Sprague-Dawley ; Thioacetamide/*toxicity

Carcinoma of the uterine cervix is one of the most common malignancies among women worldwide. Human papillomaviruses (HPV) have been identified as the major etiological factor in cervical carcinogenesis. However, the time lag between HPV infection and the diagnosis of cancer indicates that multiple steps, as well as multiple factors, may be necessary for the development of cervical cancer. The development and progression of cervical carcinoma have been shown to be dependent on various genetic and epigenetic events, especially alterations in the cell cycle checkpoint machinery. In mammalian cells, control of the cell cycle is regulated by the activity of cyclin-dependent kinases (CDKs) and their essential activating coenzymes, the cyclins. Generally, CDKs, cyclins, and CDK inhibitors function within several pathways, including the p16INK4A-cyclin D1-CDK4/6-pRb-E2F, p21WAF1-p27KIP1-cyclinE-CDK2, and p14ARF-MDM2-p53 pathways. The results from several studies showed aberrant regulation of several cell cycle proteins, such as cyclin D, cyclin E, p16 INK4A, p21WAF1, and p27KIP1, as characteristic features of HPV- infected and HPV E6/E7 oncogene-expressing cervical carcinomas and their precursors. These data suggested further that interactions of viral proteins with host cellular proteins, particularly cell cycle proteins, are involved in the activation or repression of cell cycle progression in cervical carcinogenesis.
Uterine Cervical Neoplasms/*pathology ; Tumor Suppressor Protein p53/physiology ; Tumor Suppressor Protein p14ARF/physiology ; Retinoblastoma Protein/physiology ; Proto-Oncogene Proteins c-mdm2/physiology ; Humans ; Female ; E2F Transcription Factors/physiology ; Cyclin-Dependent Kinase Inhibitor p27/physiology ; Cyclin-Dependent Kinase Inhibitor p21/physiology ; Cyclin-Dependent Kinase Inhibitor p16/physiology ; Cyclin-Dependent Kinase 4/physiology ; Cyclin-Dependent Kinase 2/physiology ; Cyclin E/physiology ; Cyclin D1/physiology ; Cell Cycle/*physiology

OBJECTIVETissue kallikrein cleaves kininogen substrate to produce vasoactive kinin peptides that have been implicated in the proliferation of vascular smooth muscle cells. We investigated the effects of adenovirus-mediated human tissue kallikrein (Ad-hKLK1) gene delivery on the proliferation of vascular smooth muscle cells of SHR (VSMCs(SHR)) induced by platelet derived growth factor-BB (PDGF-BB).

METHODSPrimary VSMCs(SHR) were isolated and cultured from thoracic aorta of male SHR. The VSMCs(SHR) proliferation induced by PDGF-BB was accessed by cell counting and methyl thiazolyl tetrazolium (MTT). Western blot was used to determine the protein expression of hKLK1, the cycle-independent kinase inhibitors p27(Kip1) and p21(Cip1). The mRNA expressions of bradykinin B1 receptor and B2 receptor were detected by RT-PCR in VSMCs(SHR).

RESULTSProliferation of VSMCs(SHR) induced by PDGF-BB was significantly inhibited post transfection of Ad-hKLK1 (20-100 MOI) in a MOI-dependent manner. The peak inhibition titer of Ad-hKLK1 was 100 MOI with peak inhibition rate of 39.3% (cell counting, n = 3, P < 0.01), 30.2% (MTT, n = 3, P < 0.01) and 36.4% (peak stunning rate of cell-cycle in phase G(0)/G(1)). The inhibitory effects of proliferation and cell-cycle caused by hKLK1 gene delivery could be abolished by Hoe140, a bradykinin B2 receptor antagonist. The protein expression of p27(Kip1) and p21(Cip1) increased significantly after the hKLK1 gene delivery, whereas Hoe140 nearly completely blocked these effects (n = 3, P < 0.001, respectively). PDGF-BB also significantly upregulated the mRNA expression of B2 receptor but not B1 receptor in VSMCs(SHR).

CONCLUSIONThe hKLK1 gene delivery could inhibit PDGF-BB induced proliferation in VSMCs(SHR) through Bradykinin B2 receptor and up-regulate expression of p27(Kip1) and p2l(Cip1).

Animals ; Cell Division ; drug effects ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p27 ; metabolism ; Humans ; Kallikreins ; genetics ; pharmacology ; Male ; Muscle, Smooth, Vascular ; cytology ; drug effects ; Rats ; Rats, Inbred SHR ; Recombination, Genetic