PURPOSE: The study was aimed to detect the induction of apoptosis, cell cycle arrest and calcified nodule formation after irradiation on primarily cultured osteoblasts. MATERIALS AND METHODS: Using rat calvarial osteoblasts, the effects of irradiation on apoptosis, cell cycle arrest, and calcified nodule formation were studied. The single irradiation of 10, 20 Gy was done with 5.38 Gy/min dose rate using the 137Cs cell irradiator at 4th and 14th day of culture. Apoptosis induction and cell cycle arrest were assayed by the flowcytometry at 1, 2, 3, and 4 days after irradiation. The formation of calcified nodules was observed by alizarin red staining at 1, 3, 10, 14 days after irradiation at 4th day of culture, and at 1, 4, 5 days after irradiation at 14th day of culture. RESULTS: Apoptosis was not induced by 10 or 20 Gy independent of irradiation and culture period. Irradiation did not induced G1 arrest in post-irradiated ostedblasts. After irradiation at 4th-day of culture, G2 arrest was induced but it was not statistically significant after irradiation at 14th-day of culture. In the case of irradiated cells at 4th day of culture, calcified nodules were not formed and at 14th-day of culture after irradiation, calcified nodule formation did not affected. CONCLUSION: Taken together, these results suggest that irradiation at the dose of 10-20 Gy would not affect apoptosis induction of osteoblasts. Cell cycle and calcified nodule formation were influenced by the level of differentiation of osteblasts.
Animals ; Apoptosis* ; Cell Cycle Checkpoints* ; Cell Cycle* ; Osteoblasts* ; Rats*

PURPOSE: Phenylbutyrate is an effective redifferentiating agent in several human cancers. Recently phenylbutyrate has been reported to inhibit histone deacetylase activity. We investigated the effects of sodium 4-henylbutyrate (Na-4-PB) on cell proliferation in a human pancreatic cancer cell line. METHODS: A human pancreatic cancer cell line, Aspc-1 was purchased from Korean Cell Line Bank. Antiproliferative effects of sodium 4-phenylbutyrate were measured by MTT assay and their mechanisms were evaluated by apoptosis assay and cell cycle analysis. RESULTS: After 3 days of treatment with Na-4-PB at the concentration of 2.5, 5, 7.5, and 10 mM, relative growth inhibition compared to control was 21.3+/-8.3% (mean+/-SD), 37.8+/-2.3%, 46.7+/-0.5%, and 56.7+/-1.7% respectively (p < 0.05). Antiproliferative effect of Na-4-PB was also time-dependent. Combination treatment with Na-4-PB and troglitazone, a PPARg agonist, increased antiproliferative effects but was not synergistic. After 48 hour treatment with Na-4-PB, early apoptotic cell population in control, 2.5, and 5 mM of Na-4-PB was 29.6%, 44.2%, and 65.9%, respectively. After 24 hour treatment with Na-4- PB, G0/G1 phase population in control, 2.5, and 5 mM of Na-4-PB was 55.0%, 67.4%, and 65.8%, respectively. CONCLUSION: Na-4-PB inhibited pancreatic cancer cell proliferation by inducing apoptosis and cell cycle arrest at G0/G1 phase in time- and dose-dependent manner. Combination treatment with Na-4-PB and other chemotherapeutic agents such as troglitazone, a PPARg agonist, can enhance antiproliferative effects. Na-4-PB might be a promising potential therapeutic agent for patients with pancreatic cancer.
Apoptosis ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Line* ; Cell Proliferation ; Histone Deacetylases ; Humans ; Pancreatic Neoplasms* ; Sodium

OBJECTIVE: The effectiveness of gamma knife radiosurgery to malignant glioma has been controversial. The goal of this study is to elucidate the in vitro biological response of malignant glioma cells to gamma knife radiosurgery. METHODS: The human glioma cell lines U87 MG (p53-wild type) and U373 MG (p53-mutant type) were irradiated in vitro via Gamma Knife 23004B2 using specially designed well holder, with a maximal dose of 10, 20, 40, 80Gy. Those two cell lines were used to study a variety of gamma knife effects on morphological change by microscopic observation, on cell viability by MTT assay, on postirradiated apoptosis by annexin assay, and on cell cycle by flow cytometry. RESULTS: With increasing dosage, more spheroid cells were observed in tumor cells and this phenomenon peaked at the second day after gamma knife irradiation. MTT assay performed 3 hours after irradiation revealed reduced cell survival in the cells irradiated with over 20Gy (p=0.000). The annexin assay showed that apoptosis tended to increase on escalating the radiation dose in U87 cells. G2-M phase cell cycle arrest markedly increased 48 hours after irradiation, and this was more exaggerated in U373 MG than in U87 MG. CONCLUSION: These results suggest that the biological effect of gamma knife on malignant glioma cell line in vitro is mainly mediated by G2-M phase cell cycle arrest.
Apoptosis ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Line* ; Cell Survival ; Flow Cytometry ; Glioma* ; Humans ; Radiosurgery

OBJECTIVE: To investigate the effect of atovaquone on the cell cycle and apoptosis of non-Hodgkin's lymphoma Raji cells, and clarify the related mechanisms. METHODS: MTT assay and trypan blue dye exclusion method were used to evaluate the effect of atovaquone on the proliferation of Raji cells. After the cells were stained by PI staining, the cell cycle distribution was detected by flow cytometry. Cell apoptosis was analyzed by Annexin V/PI double binding assay. The intracellular alterations of reactive oxygen species were detected by 2', 7'-dichlorofluorescein diacetate (DCFH-DA). The protein expression of cell cycle and apoptosis related molecules were detected by Western blot. RESULTS: Various concentrations of atovaquone (5-40 μmol/L) inhibited the growth of Raji cells in a concentration-dependent manner (r=0.951). The proliferation of Raji cells was significantly inhibited after treated by atovaquone (20 and 30 μmol/L) for 24, 48 and 72 h, which showed statistically different with that in the control group (P<0.01, P<0.001, P<0.001). G₁ phase arrest (P<0.01, P<0.001) and apoptosis (P<0.01) of Raji cells was induced by atovaquone (20 and 30 μmol/L) significantly for 24 h and 48 h, respectively. The expression of p-JAK2 and p-STAT3(Y705) protein were down-regulated significantly induced by atovaquone (P<0.001, P<0.05). Furthermore, atovaquone treatment could induce the decreasing of antiapoptotic protein Mcl-1, Bcl-2, and Bcl-xl expression level (P<0.05) and increasing of cleaved caspase-3 protein expression level. In addition, atovaquone could also induce the down-regulation of c-Myc (P<0.001, P<0.01) and cell cycle related molecules Cyclin D1, CDK4, and CDK6 (P<0.01, P<0.05) protein expression. CONCLUSION Atovaquone effectively inhibits cell proliferation and induces cell cycle arrest and apoptosis by suppression of STAT3 signaling pathway in Raji cells. It can be a potential therapeutic agent against non-Hodgkin's lymphoma.
Humans ; Atovaquone/pharmacology* ; Cell Cycle Checkpoints ; Apoptosis ; Lymphoma, Non-Hodgkin

PURPOSE: Retinonic acid (RA) has been reported to induce differentiation and growth inhibition in various head and neck squamous cancer cell (HNSCC) lines. We hypothesized that this growth inhi bition might be explained by RA-induced apoptosis on cell cycle arrest mechanism. Therefore, we studied the degree of RA-induced apoptosis with variable RA concentration and exposure duration. MATERIAL AND METHODS: The flow cytometric evaluation of apoptosis degree and cell cycles were carried out with 7-amino actinomycin D (7AAD) and propium iodide (PI) respectively, with var ious RA exposure durations (2, 3, 6 day) and concentrations (conrol, 10 6, 10 7, 10 8, 10 9, 10 10 mole). Two different HNSCC lines (1483, SqCC/Y1) were used and the experiment was repeated twice. RESULTS: The maximal fraction of apoptosis in 1483 and SqCC/Y1 cell lines were observed at same concentration and exposure duration (1483: 6th day & 10 6, mole, and SqCC/Y1: 6th day & 10 6 mole). In our experimental model, RA did not induce specific cell cycle arrest in these HNSCC lines. However we observed S phase fraction increase in SqCC/Y1 cell line after RA treatment. CONCLUSION: We suppossed that in HNSCC lines, RA-induced cell growth inhibition could be explained by not only RA-induced apoptosis but also cell cycle arrest. Futher, in vitro study has been carried out to elucidate the RA-iduced cell growth inhibition mechanism in our laboratory.
Apoptosis ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Line* ; Dactinomycin ; Head* ; Models, Theoretical ; Neck* ; S Phase ; Tretinoin

PURPOSE: Dieckol, a phlorotannin compound isolated from Ecklonia cava, has been reported to have antioxidant, antiviral, anti-inflammatory, and anticancer properties. The purpose of this study was to investigate its anticancer effects on human breast cancer cell lines. METHODS: In this study, the viability of two human breast cancer cell lines SK-BR-3 and MCF-7 was investigated after dieckol treatment using a WST-1 assay. Apoptosis and cell cycle distribution were assayed via Annexin V-fluorescein isothiocyanate and propidium iodide staining followed by flow cytometric analysis. Immunoblotting analysis was also performed using Bax/Bcl-2 to determine whether the dieckol-induced apoptosis was mediated by the intrinsic apoptotic pathway. RESULTS: In a dose dependent manner, dieckol reduced the number of viable cells and increased the number of apoptotic cells. The effect of dieckol on the cell cycle distribution was analyzed using flow cytometry. Dieckol treatment significantly increased the percentage of MCF-7 and SK-BR-3 in the G2/M phase. Immunoblot analysis revealed that 24 hours of dieckol exposure increased the Bax/Bcl-2 ratio. CONCLUSION: Dieckol induced cytotoxicity in MCF-7 and SK-BR-3 human breast cancer cells inducing apoptosis and cell cycle arrest. Therefore, it is suggested that dieckol may be a potential therapeutic agent for breast cancer.
Apoptosis* ; Breast Neoplasms* ; Breast* ; Cell Cycle Checkpoints* ; Cell Cycle* ; Cell Line* ; Flow Cytometry ; Humans* ; Immunoblotting ; Propidium

PURPOSE: p53 and p21 act as a cell cycle regulator. p21 has been thought to be an important mediator of p53-induced cell cycle arrest. p53 alterations can induce the uncontrolled growth of tumor cells by loss of p21 expression in cancer patients. The objective of this study was to characterize the alterations of p53 and p21 expression and to assess the relationship between p53 and p21 in bladder cancer patients. MATERIALS AND METHODS: p53 and p21 expressions were evaluated immunohistochemically in 97 patients of bladder cancer according to grade, stage and recurrence. We compared p53 expression with p21. Nuclear expression was scored as negative, patchy(<20%), heterogeneous(20-75%) or homogeneous(>75%). RESULTS: p53 was expressed in 34(35.1%) of 97 patients and p21 in 23 patients(23.7%). p53 expression was significantly related with grade(18.2% in lower grade vs. 71% in higher) and stage(18.2% in superficial vs. 57.1% in invasive). p21 was not expressed in 74(76.3%) of 97 patients and not correlated with grade and stage. Recurrence in superficial bladder cancer was lower for patients with p53-negative(27%) than patients with p53-positive(64.3%). There was no correlation between loss of p21 expression and recurrence. Inverse expression of these two proteins was seen in 39 patients(40.2%). CONCLUSIONS: These results suggest that p21 is induced by p53-dependent pathway, but that there may also indicate p53-independent pathways of induction. p53 could be a reliable indicator of recurrence in superficial bladder cancer.
Cell Cycle ; Cell Cycle Checkpoints ; Humans ; Immunohistochemistry ; Recurrence ; Urinary Bladder Neoplasms* ; Urinary Bladder*

Genetic instability is considered to be a major driving force of malignancy of cancer cells, and at least some of cancer-associated genetic instability is known to be caused by defects in the cell cycle checkpoint control. Patients of the cancer-prone genetic disorder ataxia telangiectagia frequently develop malignant lymphoma and their cells are defective in gamma-irradiation responsive checkpoint control, whereas cells inactivated for the p53 recessive oncoprotein are defective in DNA damage-induced checkpoint control and develop genetic instability. Cells contain two major cell cycle checkpoint control systems: DNA-replication checkpoint, DNA-damage checkpoint. These checkpoint systems are thought to consist of three functionally distinct components: sensors, checkpoint signal transducers and cell cycle effecters. Recent rapid progress in the identification of these components is beginning to prove this conceptual model and the generality of the checkpoint system among eukaryotes. The full understanding of the cell cycle checkpoint control system will provide deeper insights into the highly complex mechanisms of carcinogenesis and highlight possible targets for cancer therapy.
Ataxia ; Carcinogenesis ; Cell Cycle Checkpoints* ; Cell Cycle* ; DNA ; DNA Damage ; DNA Replication ; Eukaryota ; Humans ; Lymphoma ; Transducers

PURPOSE: This study was aimed to investigate the role of poly(A)-binding protein-interacting protein 1 (Paip1) in cervical carcinogenesis. MATERIALS AND METHODS: The expression of Paip1 in normal cervical epithelial tissues and cervical cancer (CC) tissues were detected by immunohistochemistry. In vivo and in vitro assays were performed to validate effect of Paip1 on CC progression. RESULTS: Paip1 was found to be up-regulated in CC, which was linked with shorter survival. Knockdown of Paip1 inhibited cell growth, induced apoptosis and cell cycle arrest in CC cells, whereas its overexpression reversed these effects. The in vivo tumor model confirmed the pro-tumor role of Paip1 in CC growth. CONCLUSION: Altogether, the investigation demonstrated the clinical significance of Paip1 expression, which prompted that the up-regulated of Paip1 can presumably be a potential prognostic and progression marker for CC.
Apoptosis ; Carcinogenesis ; Cell Cycle ; Cell Cycle Checkpoints ; Immunohistochemistry ; In Vitro Techniques ; Prognosis ; Uterine Cervical Neoplasms

BACKGROUND: Type I collagen is a major component of extracellular cellular matrix in tissue. It is synthesized by human skin fibroblasts. However, synthesis of type I collagen is markedly-decreased in senescent fibroblasts. In the cell cycle, the hallmark of senescent fibroblasts is a permanent G1 phase arrest. However it is largely unknown whether the expression of type I collagen protein is decreased by the G1 phase arrest in human skin fibroblasts after UVB irradiation, serum starvation, or mimosine, an inducer of the G1 phase arrest treatment. OBJECTIVE: The purpose of this study was to investigate the expression of type I collagen protein in G1 phase- arrested human skin fibroblasts after UVB irradiation, serum starvation, and mimosine treatment. METHODS: To induce G1 phase arrest in the cell cycle, human skin fibroblasts were irradiated by UVB (100, 200, 300 mJ/cm(2)), subjected to serum starvation for 5 days, or mimosine treatment (50, 100, 200 uM). The expressions of type I collagen protein were analyzed by Western blot analysis. RESULTS: The G1 phase of cell populations were increased by a dose or time-dependent manner with UVB irradiation, serum starvation, and mimosine-treated human skin fibroblasts. The expression of type I collagen protein was markedly-decreased by UVB, serum starvation, and mimosine treatment. CONCLUSION: The expression of type I collagen protein in human skin fibroblasts is decreased by UVB irradiation, serum starvation, and mimosine treatment through induction of G1 phase cell cycle arrest.
Blotting, Western ; Cell Cycle ; Cell Cycle Checkpoints ; Collagen Type I* ; Down-Regulation* ; Fibroblasts* ; G1 Phase ; G1 Phase Cell Cycle Checkpoints* ; Gene Expression* ; Humans* ; Mimosine ; Skin* ; Starvation