To explore the hematopoiesis inhibition mechanisms of interferon-gamma (IFN-gamma), the effects of IFN-gamma on the expression of the cyclin D in the umbilical cord blood hematopoietic stem/progenitor cells were observed. In the experiments the CD34(+) cells were isolated from the cord blood with MIDI-MACS system; semi-solid methylcellulose culture technique was used to measure the formation of CFU-GM; the expression levels of cyclin D isoforms were assayed by semi-quantitative RT-PCR, after the hematopoietic stem/progenitor cells were incubated with IFN-gamma. The results indicated that IFN-gamma could inhibit the formation of CFU-GM and down-regulate the expression of cyclin D2 and cyclin D3 at the mRNA level. It is concluded that the IFN-gamma could inhibit the proliferation of hematopoietic stem cells and down-regulate the expression of cyclin D, that may be one mechanism underlying the hematopoietic inhibition of IFN-gamma.
Cyclin D ; Cyclins ; genetics ; Fetal Blood ; cytology ; G1 Phase ; Hematopoietic Stem Cells ; drug effects ; metabolism ; Humans ; Interferon-gamma ; pharmacology ; Protein Isoforms ; RNA, Messenger ; analysis

Dexamethasone converts pluripotent pancreatic AR42J cells into exocrine cells expressing digestive enzymes. In order to address molecular mechanism of this differentiation, we have investigated the role of mitogen-activated protein (MAP) kinase pathway and gene expressions of p21(waf1/cip1)and nuclear oncogenes (c-fos and c-myc) during AR42J cell differentiation. Dexamethasone markedly increased the intracellular and secreted amylase contents as well as its mRNA level. However, cell growth and DNA content were significantly decreased. With these phenotypic changes, AR42J cells induced transient mRNA expression of p21(waf1/cip1)gene, which reached maximal level by 6 h and then declined gradually toward basal state. In contrast to p21(waf1/cip1), c-fos gene expression was transiently inhibited by 6 h and then recovered to basal level by 24 h. Increased c-myc expression detected after 3 h, peaked by 12 h, and remained elevated during the rest of observation. Dexamethasone inhibited epidermal growth factor-induced phosphorylation of extracellular signal regulated kinase. Inhibition of MAP kinase pathway by PD98059 resulted in further elevation of the dexamethasone-induced amylase mRNA and p21(waf1/cip1)gene expression. These results suggest that p21(waf1/cip1)and nuclear oncogenes are involved in dexamethasone-induced differentiation and inhibition of MAP kinase pathway accelerates the conversion of undifferentiated AR42J cells into amylase-secreting exocrine cells.
Amylases/genetics ; Animals ; Cell Differentiation/*drug effects ; Cell Division/drug effects ; Cell Line, Tumor ; Cyclins/genetics/*metabolism ; Dexamethasone/*pharmacology ; Gene Expression Regulation/drug effects ; Genes, fos/genetics ; Genes, myc/genetics ; MAP Kinase Signaling System/*drug effects ; Mitogen-Activated Protein Kinases/*metabolism ; Pancreas/cytology/*drug effects/enzymology/metabolism ; RNA, Messenger/genetics/metabolism ; Rats ; Support, Non-U.S. Gov't

OBJECTIVETo explore the effect of p21(WAF1) on the proliferation and the sensitivity to Vp16 of leukemia cell line K562.

METHODSA p21(WAF1) retroviral expression vector pLXSN-p21(WAF1) was constructed by FuGENE 6, pLXSN-p21(WAF1) and pLXSN-neo, and transfected into p21(WAF1) defect leukemia cell line K562. After selected with G418, K562-p21(WAF1) cell clones that stably expressed p21(WAF1) were isolated. The ectopic expressions of p21(WAF1) mRNA and protein in K562-p21(WAF1) were identified by RT-PCR and Western b1ot. The cell growth rate was tested by trypan blue dye, the cell cycle by FCM and the sensitivity to Vpl6 by cell count and MTT assay.

RESULTSThe expression of p21(WAF1) protein and mRNA could be detected in K562-p21(WAF1) cells. A strong inhibition of cell proliferation was observed in K562-p21(WAF1) cell as compared with that of the control. The cell number in G(0)/G(1) phase was remarkably increased. The sensitivity to Vpl6 decreased, the IC (50) of K562-neo cells was (56.4 +/- 6.5) microgram/ml, and that of K562-p21(WAF1) cells was (131.0 +/- 8.7) microgram/ml (P < 0.01).

CONCLUSIONp21(WAF1) can inhibit the proliferation of leukemia cell and decrease its sensitivity to Vp16.

Antineoplastic Agents, Phytogenic ; pharmacology ; Blotting, Western ; Cell Division ; drug effects ; Cell Survival ; drug effects ; Cyclin-Dependent Kinase Inhibitor p21 ; Cyclins ; genetics ; metabolism ; physiology ; Dose-Response Relationship, Drug ; Etoposide ; pharmacology ; G1 Phase ; drug effects ; Gene Expression ; Humans ; K562 Cells ; cytology ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Resting Phase, Cell Cycle ; drug effects ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors

Repetitive low dose thioacetamide (TA) treatment of hepatocytes was found to induce cells in G2 arrest. In the present study, an attempt was made to investigate alterations in expression of cell cycle regulators after G1 progression in the same repetitive low dose TA treated hepatocytes system and to define the determinators involved in G2 arrest. TA was daily administered intraperitoneally, with a dose of 50 mg/kg for 7 days. Expression levels of cyclin E and CDK2 were similar, increased at day 1 and reached a peak at day 2. And they recycled from day 3 reaching a second peak at day 5. Expression level of cyclin A was similar to p27(Kip1) and p57(Kip2) but not to CDK2 and increased to a peak level at day 2. Expression levels of cyclin B1 and cdc2 were similar although the cyclin B1 level was generally low, decreased from day 1 to basal levels at day 3 and persisted at a low level till day 7. The expression level of cyclin G1 was similar to p53 that peaked at day 3 and again at day 6 elevated over basal level. BrdU-labeled hepatocytic nuclei increased from 12 h, reached a peak at day 2, then decreased, and were not detectable from day 6. The number of PCNA-labeled nuclei increased immediately, peaked at day 2, and maintained till day 7. These results suggest that G2 arrest induced by repeated TA treatment might be p53-dependent, via activation of cyclin G1, rather than inhibition of cyclin B1- cdc2 complex, and inhibitors holding S phase progression might be p27(Kip1) and p57(Kip2).
Animals ; Bromodeoxyuridine/metabolism ; CDC2 Protein Kinase/drug effects/metabolism ; *CDC2-CDC28 Kinases ; Cell Cycle/drug effects/*physiology ; Cell Cycle Proteins/drug effects/metabolism ; Cyclin-Dependent Kinases/antagonists & inhibitors/drug effects/metabolism ; Cyclins/drug effects/metabolism ; Dose-Response Relationship, Drug ; G1 Phase/drug effects/*physiology ; Liver/*drug effects/pathology ; Male ; Nuclear Proteins/drug effects/metabolism ; Proliferating Cell Nuclear Antigen/metabolism ; Protein p53/metabolism ; Protein-Serine-Threonine Kinases/antagonists & inhibitors/drug effects/metabolism ; Rats ; Rats, Sprague-Dawley ; Thioacetamide/administration & dosage/*pharmacology ; Tumor Suppressor Proteins/drug effects/metabolism

Epidemiological studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of colon cancer. In addition, NSAIDs reduce the number and size of polyps in patients with familial adenomatous polyposis. The mechanisms of the anti-neoplastic effect of NSAIDs are still far from complete understanding, but one possible mechanism is the induction of apoptosis. Several lines of evidence suggest that NSAIDs-induced apoptosis in colon cancer cells are mediated through the cyclooxygenase (COX)-independent pathway. In this study we explored the mechanism of NSAIDs-induced apoptosis in the colon cancer cell line, HT-29. We confirmed that NSAIDs induce apoptosis in HT-29 cells irrespective of their COX-selectivity. Indomethacin enhanced the expression of p21waf-1 in HT-29 cells. However the expression of apoptosis-related genes such as Fas, bcl-2 and bax was not affected by indomethacin. Intra- and extra-cellular calcium chelators, protein tyrosine kinase (PTK) inhibitor, protein kinase A (PKA) inhibitor and protein kinase C (PKC) inhibitors did not influence indomethacin-induced apoptosis in HT-29 cells. We concluded that NSAIDs-induced apoptosis in colon cancer cells may be independent from signals transducted through [Ca++]i, PTK, PKA, PKC or the expression of apoptosis-related genes. In contrast, our results demonstrating the induction of p21waf-1 transcription by NSAIDs suggest the possible association of NSAIDs-induced apoptosis and cell-cycle control in colon cancer cells.
Anti-Inflammatory Agents, Non-Steroidal/pharmacology* ; Apoptosis/drug effects* ; Calcium/metabolism ; Cell Survival/drug effects ; Colonic Neoplasms/prevention & control* ; Colonic Neoplasms/pathology ; Cyclins/genetics ; Cyclins/biosynthesis ; HT29 Cells ; Human ; Protein Kinases/physiology ; Protein p53/physiology ; Proto-Oncogene Proteins c-bcl-2/analysis ; RNA, Messenger/analysis

It has been known that estrogen-17beta stimulates proliferation of mouse embryonic stem (mES) cells. To explore the function of another steroid hormone progesterone, we used MTT method and BrdU incorporation assay to obtain growth curves, clone forming assay to detect the propagation and viability of individual mES cells, Western blot to test the expression of ES cell marker gene Oct-4, fluorescence activated cell sorter (FACS) to test cell cycle, and real-time PCR to detect the expressions of cyclins, cyclin-dependent kinases and proto-oncogenes. The results showed that progesterone promoted proliferation of mES cells. The number of clones was more in progesterone-treated group than that in the control group. The expression of pluripotency-associated transcriptional factor Oct-4 changed little after progesterone treatment as shown by Western blot, indicating that most of mES cells were in undifferentiated state. The results of FACS proved that progesterone promoted DNA synthesis in mES cells. The proportion of mES cells in S+G(2)/M phase was higher in progesterone-treated group than that in the control group. Cyclins and cyclin-dependent kinases, as well as proto-oncogenes (c-myc, c-fos) were up-regulated when cells were treated with progesterone. The results obtained indicate that progesterone promotes propagation and viability of mES cells. The up-regulation of cell cycle-related factors might contribute to the function of progesterone.
Animals ; Cell Division ; Cells, Cultured ; Cyclin-Dependent Kinases ; metabolism ; Cyclins ; metabolism ; Embryonic Stem Cells ; cytology ; drug effects ; Mice ; Octamer Transcription Factor-3 ; metabolism ; Progesterone ; pharmacology ; Proto-Oncogenes ; Up-Regulation

OBJECTIVESThis study is to investigate the effects of tea polyphenols and tea pigments on cell cycle regulators in rat liver precancerous lesions.

METHODSThe modified Solt-Farber precancerous liver rat model was used. Rats were given water, tea polypheol solution (0.1%) or tea pigment solution (0.1%) throughout the whole experiment (56 days). Cyclin D1, P21(WAF1/CIP1), GADD45 and PCNA protein expression were detected by Western blotting and the RT-PCR method was applied to study the expression of Cdk4.

RESULTSCyclin D1, Cdk4 and PCNA expressions were significantly inhibited, and the expression of P21(WAF1/CIP1) and GADD45 were significantly induced by tea polyphenols and tea pigments treatments.

CONCLUSIONTea polyphenols and tea pigments induced cell cycle arrest and inhibited cell proliferation by regulating cell cycle regulators.

Animals ; Blotting, Western ; Cell Cycle Proteins ; drug effects ; genetics ; metabolism ; Cyclin D1 ; drug effects ; metabolism ; Cyclin-Dependent Kinase 4 ; Cyclin-Dependent Kinase Inhibitor p21 ; Cyclin-Dependent Kinases ; genetics ; Cyclins ; drug effects ; metabolism ; Flavonoids ; Intracellular Signaling Peptides and Proteins ; Liver Neoplasms ; genetics ; metabolism ; pathology ; Male ; Phenols ; pharmacology ; Pigments, Biological ; pharmacology ; Polymers ; pharmacology ; Polyphenols ; Precancerous Conditions ; genetics ; metabolism ; pathology ; Proliferating Cell Nuclear Antigen ; drug effects ; metabolism ; Proteins ; Proto-Oncogene Proteins ; RNA, Messenger ; drug effects ; genetics ; metabolism ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction ; Tea ; chemistry

American ginseng (AG) has been demonstrated to inhibit breast cancer cell growth in vitro. p21 protein, a universal cell cycle inhibitor, binds cyclin-CDK complexes, an important mechanism in cell cycle regulation. The purpose of this investigation was to determine if AG induces p21 gene expression in hormone sensitive (MCF-7) and insensitive (MDA-MB-231) breast cancer cell lines. Cells grown in steroid stripped medium (SSM) were treated with AG, 17-beta-estradiol (E2), genistein or cycloheximide (CHX). Northern blot analyses were performed using human p21Cip1 and 36B4 cDNA probes. Cell lines were transiently transfected with select mouse p21 CAT reporter constructs, including those lacking a p53 binding site. Cell cycle analyses was performed by FACScan. The results revealed that AG induced p21 mRNA expression in MCF-7 and MDA-MB-231 cells (p=0.0004; p< or =0.0001, respectively). Neither E2 nor genistein alter p21 mRNA expression. CHX, a protein synthesis inhibitor, did not block p21 mRNA expression induced by AG, indicating that p21 is induced as an immediate early gene. AG activated p21 reporter constructs in transfected cells, independent of p53 binding sites. The cell cycle proliferative phase was significantly decreased by AG and increased by E2 (p< or =0.0001). AG may inhibit breast cancer cell growth by transcriptional activation of the p21 gene, independent of p53.
Animal ; Binding Sites ; Breast Neoplasms ; Cell Division/drug effects ; Chloramphenicol O-Acetyltransferase/genetics ; Cyclins/*genetics ; Female ; Genes, Reporter ; HT29 Cells ; Human ; Mice ; *Panax ; Plant Extracts/pharmacology ; Protein p53/metabolism ; *RNA, Messenger ; *Trans-Activation (Genetics) ; Tumor Cells, Cultured

Animals ; Antineoplastic Agents ; pharmacology ; therapeutic use ; Cell Cycle ; drug effects ; physiology ; Cyclin-Dependent Kinases ; antagonists & inhibitors ; metabolism ; Cyclins ; metabolism ; Flavonoids ; pharmacology ; therapeutic use ; Humans ; Neoplasms ; drug therapy ; metabolism ; pathology ; Piperidines ; pharmacology ; therapeutic use ; Purines ; pharmacology ; therapeutic use ; Staurosporine ; analogs & derivatives ; pharmacology ; therapeutic use