Humans ; Cyclin D1 ; Melanoma ; Skin Neoplasms ; Cyclin-Dependent Kinase 4

The development and progression of most cancers have been well recognized as the result of highly activated cell cycle. Cyclin dependent kinase 4/6 plays important roles not only in mitosis, but also in multiple biological processes that contribute to cancer development, such as aging, apoptosis and histone modification. Three FDA approved CDK4/6 inhibitors, Palbociclib, Ribociclib and Abemaciclib, have been used as targeted cancer therapeutic agents to benefit patients with endocrine therapy-resistant breast cancer and other types of cancer, prolonging their survival. However, the clinical application of these inhibitors also leads to acquired drug resistance and other problems. This paper reviews the regulatory roles of CDK4/6, the application of CDK4/6 inhibitors in cancer and the challenge of drug resistance.
Breast Neoplasms ; Cyclin-Dependent Kinase 4/therapeutic use* ; Cyclin-Dependent Kinase 6/therapeutic use* ; Female ; Humans ; Molecular Targeted Therapy ; Protein Kinase Inhibitors/therapeutic use* ; Signal Transduction

OBJECTIVETo investigate the effect of PD98059 on the proliferation and cell cycle of rat hepatic stellate cells (HSCs) stimulated by acetaldehyde and explore its mechanism.

METHODSRat HSCs stimulated by acetaldehyde were incubated with different concentrations of PD98059. Cell proliferation was assessed by MTT colorimetric assay. Cell cycle was analysed by flow cytometry. The mRNA of cyclin D1 and CDK4 were examined by RT-PCR.

RESULTS20, 50, 100 micromol/L PD98059 could significantly inhibit the proliferation of HSCs stimulated by acetaldehyde in a does-dependent manner (0.109+/-0.020, 0.081+/-0.010 and 0.056+/-0.020 vs 0.146+/-0.030, F=31.385, P<0.05) and provoke G0/G1 phase arrest of HSCs stimulated by acetaldehyde in a does-dependent manner (61.9%+/-6.3%, 64.1%+/-3.3% and 70.9%+/-4.8% vs 55.2%+/-4.4%, F=16.402, P<0.05). 50, 100 micromol/L PD98059 could markedly inhibit cyclin D1 mRNA expression of HSC stimulated by acetaldehyde (0.56+/-0.04 and 0.46+/-0.03 vs 0.65+/-0.07, F=68.758, P<0.05) and CDK4 mRNA expression (0.39+/-0.07 and 0.33+/-0.05 vs 0.50+/-0.06, F=29.406, P<0.05).

CONCLUSIONThe Erk signal transduction pathway plays an important role in regulating the proliferation and cell cycle of rat hepatic stellate cells stimulated by acetaldehyde, which may be partly related to its regulative effect on the expression of cyclin D1 gene and CDK4 gene

Acetaldehyde ; pharmacology ; Animals ; Cells, Cultured ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 4 ; Cyclin-Dependent Kinases ; metabolism ; Enzyme Inhibitors ; pharmacology ; Flavonoids ; pharmacology ; Hepatocytes ; drug effects ; Proto-Oncogene Proteins ; Rats

BACKGROUND: Altered cell cycle regulation may underlie the development and/or progression of human malignancies. The purpose of this study is to determine if the oncogenesis of soft tissue sarcomas could be better explained by examining the components involved in G1 phase progression. METHODS: Sixty-seven soft tissue sarcomas were studied for the immunohistochemical expression of cdk4, cyclin D1, retinoblastoma (Rb) and p16 proteins. For Rb and p16, samples showing either negative or heterogeneous (<80% of tumor cells) staining were considered to be altered. RESULTS: The cdk4 protein was observed in 64 cases (95.5%). Cyclin D1 was expressed in 14 cases (20.9%). The Rb expression was altered in 48 (71.6%). Sixty-three (94%) sarcomas demonstrated altered p16 expressions. All of the samples displayed altered expressions of either Rb or p16. A high percentage of the tumors with altered Rb were observed in relapsed patients (p<0.05). CONCLUSIONS: Disturbance in the cell cycle regulatory system involving the Rb/p16/cdk4/cyclin D1 pathway appears to be relatively frequent in soft tissue sarcomas and may play an important role in the tumorigenesis of these tumors. It is noteworthy that the reduced Rb expression correlates with tumor relapse, suggesting its prognostic significance.
Carcinogenesis ; Cell Cycle ; Cyclin D1* ; Cyclin-Dependent Kinase 4 ; Cyclins* ; G1 Phase ; Humans* ; Recurrence ; Retinoblastoma ; Retinoblastoma Protein* ; Sarcoma*

Glioblastoma is a common brain tumor and the overall survival rate of the patients is very low, so it is an effective way to develop the potential chemotherapy or adjuvant chemotherapy drugs in glioblastoma treatment. As a well-known antimalarial drug, artesunate(ARTs) has clear side effects, and recently it has been reported to have antitumor effects, but rarely reported in glioblastoma. Different concentrations of ARTs were used to treat the glioblastoma cells, and then the inhibitory effect of ARTs on glioblastoma proliferation was detected by MTT assay; Ki67 immunofluorescence assay was used to detect the proliferation of cells; Soft agar experiment was used to explain the clonal formation abilities ; Flow Cytometry was used to detect the cell cycle; and Western blot assay was used to determine the expression of key cell cycle protein. MTT assay results indicated that ARTs-treated glioblastoma cell A172, U251, U87 were significantly inhibited in a time-and-dose dependent manner as compared to the control group(DMSO treatment group). Soft agar experiment showed that ARTs could significantly reduce the clonal formation ability of glioblastoma. Furthermore, Flow cytometry analysis showed that ARTs could obviously increase the cell proportion in G₀/G₁ phase and reduce the cell proportion in S phase. Western blot results showed that the expressions of cell cycle-related proteins CDK2, CDK4, cyclin D1 and cyclin B1 were all obviously down-regulated. Above all, ARTs may inhibit the proliferation of glioblastoma cells by arresting cell cycle in G₀/G₁ phase through down-regulating the expression of CDK2, CDK4, cyclin D1, cyclin B1. These results may not only provide a novel method for rediscovering and reusing ARTs but also provide a new potential drug for treating glioblastoma.
Antineoplastic Agents ; pharmacology ; Apoptosis ; Artesunate ; pharmacology ; Cell Cycle Checkpoints ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cyclin B1 ; metabolism ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 2 ; metabolism ; Cyclin-Dependent Kinase 4 ; metabolism ; Glioblastoma ; drug therapy ; pathology ; Humans

Mitochondria continuously fuse and divide to maintain homeostasis. An impairment in the balance between the fusion and fission processes can trigger mitochondrial dysfunction. Accumulating evidence suggests that mitochondrial dysfunction is related to neurodegenerative diseases such as Parkinson's disease (PD), with excessive mitochondrial fission in dopaminergic neurons being one of the pathological mechanisms of PD. Here, we investigated the balance between mitochondrial fusion and fission in the substantia nigra of a non-human primate model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. We found that MPTP induced shorter and abnormally distributed mitochondria. This phenomenon was accompanied by the activation of dynamin-related protein 1 (Drp1), a mitochondrial fission protein, through increased phosphorylation at S616. Thereafter, we assessed for activation of the components of the cyclin-dependent kinase 5 (CDK5) and extracellular signal-regulated kinase (ERK) signaling cascades, which are known regulators of Drp1(S616) phosphorylation. MPTP induced an increase in p25 and p35, which are required for CDK5 activation. Together, these findings suggest that the phosphorylation of Drp1(S616) by CDK5 is involved in mitochondrial fission in the substantia nigra of a non-human primate model of MPTP-induced PD.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine ; Cyclin-Dependent Kinase 5 ; Cyclin-Dependent Kinases ; Dopaminergic Neurons ; Homeostasis ; Mitochondria ; Mitochondrial Dynamics ; Neurodegenerative Diseases ; Parkinson Disease ; Phosphorylation ; Phosphotransferases ; Primates ; Substantia Nigra

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

OBJECTIVETo investigate the mechanism of pilose antler polypeptides (PAP) resisting replicative senescence of rat chondrocyte serially subcultivated in vitro by means of PAP interfering and controlled experiment.

METHODSThe successive tert-generation (2nd passage, 3rd passage, 4th passage) chondrocytes and the 4th passage cells intervented by PAP were studied for senenscence mechanism. In this course, immunocytochemistry was applied for pl6, pRb, E2F, CyclinD, CDK4 and TRAP-ELISA (telomerase repeat amplification protocol assay-enzyme linked immunosorbent assay) was applied for telomerase activation to observe targets' changing regarding to senescence and the function of PAP.

RESULTSAlong with cell's replicative senescence, pl6, pRb and Cyclin D express significantly rised (P < 0.01), while E2F, CDK4 and telomerase express significantly lowerd (P < 0.01). Meanwhile, in PAP interfered group compared with which in 4th passage group, pl6, pRb and Cyclin D express significantly lowerd (P < 0.01l), while E2F, CDK4 and telomerase express significantly rised (P < 0.01).

CONCLUSIONPAP has function that it reversingly affect the express of factors which controlling cell life cycle and cell growth to postpone chondrocyte senenscence.

Animals ; Antlers ; chemistry ; Cellular Senescence ; drug effects ; Chondrocytes ; cytology ; drug effects ; Cyclin D ; Cyclin-Dependent Kinase 4 ; analysis ; Cyclin-Dependent Kinase Inhibitor p16 ; analysis ; Cyclins ; analysis ; E2F Transcription Factors ; analysis ; Peptides ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Retinoblastoma Protein ; analysis

This study was purposed to investigate the proliferation, differentiation and apoptosis of human promyelocytic leukemia HL-60 cells induced by proanthocyanidin (PAC). HL-60 cells were incubated with 20 mg/L PAC for 24 h, the cell growth was evaluated by CCK-8 assay. the effect of PAC on HL-60 cells was evaluated and the cells morphology was observed by optical microscopy. Expression of CD14 and CD11b, and cell cycle were analyzed by flow cytometry. The results showed that the growth of HL-60 cells was inhibited after treatment with PAC of different concentration in a dose-dependent manner (P < 0.05). 20 mg/L PAC displayed significant effect on HL-60 cells with inhibition ratio (72.3 ± 1.8)% for 24 h. Microscopy displayed that some cells differentiated to relative mature cells after treating for 48 h. Expression of CD14 increased and the expression of CD11b increased a little after treating with 20 mg/L PAC for 24 h, the ratio of cells in G0/G1 phase increased, but the ratio of cells in S phase decreased. The mRNA and protein expression of P21 gene increased, but the protein expression of CDK4 and Cyclin D1 decreased. It is concluded that PAC may inhibit the proliferation of HL-60 cells in vitro, induces the differentiation of HL-60 cells, and arrests the cells in G0/G1 phase. The possible mechanism may be related to up-regulation of P21 gene expression and down-regulation of the protein expression of CDK4 and Cyclin D1.
Cell Cycle Checkpoints ; drug effects ; Cell Differentiation ; drug effects ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 4 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Gene Expression Regulation, Leukemic ; HL-60 Cells ; Humans ; Proanthocyanidins ; pharmacology