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PubMed2001

15S-Hydroxyeicosatetraenoic acid activates peroxisome proliferator-activated receptor gamma and inhibits proliferation in PC3 prostate carcinoma cells.

15-Lipoxygenase (15-LOX)-2 is expressed in benign prostate secretory cells and benign prostate produces 15S-hydroxyeicosatetraenoic acid (15S-HETE) from exogenous arachidonic acid (AA). In contrast, 15S-LOX-2 and 15S-HETE formation are reduced in prostate carcinoma (Pca). The mechanisms whereby reduced 15-LOX-2 may contribute to Pca development or progression are not known. We investigated the expression of peroxisome proliferator-activated receptor (PPAR) gamma in benign and malignant prostate tissues and the ability of 15S-HETE to activate PPARgamma-dependent transcription and modulate proliferation of the Pca cell line PC3. In contrast to benign prostate and similar to most Pca tissues, 15-LOX-2 mRNA was not detected in PC3 cells, and they did not produce detectable 15-HETE from [14C]AA. By reverse transcription-PCR, PPARgamma mRNA was present in 18 of 18 benign and 9 of 9 tumor specimens. The PPARgamma ligand BRL 49653 and 15S-HETE caused a dose-dependent inhibition of PC3 proliferation in a 14-day soft agar colony-forming assay (IC50 of 3 and 30 microM, respectively). 15S-HETE (10 microM) caused greater inhibition than 10 microM 15R-HETE. At 3 days, BRL 49653 and 15S-HETE caused a slight increase in cells in G0-G1 and a corresponding decrease in cells in S phase. In PC3 cells transiently transfected with a luciferase reporter linked to a PPAR response element, 1 microM BRL 49653 and 10 microM 15S-HETE caused approximately threefold and greater than twofold induction of PPAR-dependent transcription, respectively. By quantitative real-time reverse transcription-PCR and Northern analysis, 3-day treatment with BRL 49653 and 15S-HETE caused a reduction of PPARgamma expression but a marked up-regulation of the PPAR response element containing adipocyte type fatty acid binding protein. These results support the hypothesis that 15-LOX-2-derived 15S-HETE may constitute an endogenous ligand for PPARgamma in the prostate and that loss of this pathway by reduced expression of 15-LOX-2 may contribute to increased proliferation and reduced differentiation in prostate carcinoma.

Agar↗

PubMedDate not supplied

[The nature of a proliferation block in differentiated cells with heterokaryons as a model: various types of absence of proliferation in cells in terminal differentiation].

Heterokaryons obtained by fusion of proliferating and terminally differentiated cells were studied. The data obtained suggest that mechanisms of proliferation arrest are different in macrophages on one hand and nucleate erythrocytes and polymorph leukocytes on the other. Macrophages appeared to be devoid of factors preventing replication in nontransformed and spontaneously immortalized cells. Inhibition of proliferation was probably due to certain modifications of macrophage genome which arise during differentiation and can be compensated by the effect of "immortalizing" oncogenes. On the contrary, nucleate erythrocytes and polymorphs evidently contain some factors mediating negative control of proliferation. For reactivation of DNA synthesis in these cell types after fusion with other cells the latter did not have to be immortalized. After cell fusion macrophages specifically inhibit DNA synthesis in cells containing active oncogenes.

Animals↗

PubMed1988

Relationship of hepatic peroxisome proliferation and replicative DNA synthesis to the hepatocarcinogenicity of the peroxisome proliferators di(2-ethylhexyl)phthalate and [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid (Wy-14,643) in rats.

The mechanism of hepatocarcinogenesis caused by peroxisome proliferators (PP) is poorly understood, making it difficult to predict the carcinogenicity of PP to rodents or other species. It has been suggested that the carcinogenic potential of individual PP in rodents is correlated with the degree of PP-induced hepatic peroxisome proliferation. To evaluate this possible correlation, di(2-ethylhexyl)phthalate (DEHP) at 1.2% and [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid (Wy-14,643) at 0.1% were fed to male F-344 rats for up to 365 days and hepatocytic peroxisome proliferation and DNA replication were measured. All rats fed Wy-14,643 for 365 days had numerous grossly visible nodules in comparison to none in the livers of DEHP-fed or control rats. Despite this difference in the induction of tumors, both DEHP and Wy-14,643 increased the peroxisomal volume density 4- to 6-fold from 8 to 365 days of treatment. Peroxisomal beta-oxidation enzyme activities were increased 8-fold by both DEHP and Wy-14,643 after 18 days. At later time points (77 to 365 days), these enzyme activities were about 25% higher in livers of Wy-14,643- than DEHP-fed rats. DEHP or Wy-14,643 increased absolute liver weights 50 to 75% above controls after 18 to 365 days of feeding. Labeling of hepatocyte nuclei with a single injection of tritiated thymidine revealed a rapid burst in replicative DNA synthesis in both DEHP and Wy-14,643-fed rats, with a return to control levels by 4 days. Additional rats were implanted with 7-day osmotic pumps containing tritiated thymidine. With this more extended method of labeling a 5- to 10-fold increase in replicative DNA synthesis was observed in rats receiving Wy-14,643 for 39 to 365 days as compared to DEHP-fed rats or controls. In conclusion, when performed under conditions similar to the tumorigenicity studies, the degree of peroxisome proliferation correlated poorly with the relative hepatocarcinogenicity of DEHP and Wy-14,643. However, a strong correlation was observed between the relative hepatocarcinogenicity of DEHP and Wy-14,643 and the ability to induce a persistent increase in replicative DNA synthesis. These data emphasize the possible importance of cell replication in the mechanism of PP-induced hepatocarcinogenesis.

Animals↗

PubMed1979

[Arterial intimal proliferation in the rat : nature and origin of the proliferating cells].

This study had two objectives: 1) Identification of the type of cell involved in intimal proliferation (endothelial cells, smooth muscle fibres or fibroblasts). 2) Determination of the origin. For this purpose a model was used which consisted of implantation in the rat of femoral arterial segments in the interstitial tissue. Sequential examination of tissue collected on days 1, 2, 3, 4, 5, 6, 7 revealed that proliferation was more marked if not solely present at the extremities of the segments. The proliferating cells were also in continuity with the extravascular granulation tissue, which would appear to indicate that the intimal proliferation in this model came from the cells of the granulation tissue and "muscular" differentiation occurred in contact with the endothelium.

Animals↗

PubMed1984

T cell proliferation in Mycobacterium lepraemurium infection. I. Lack of correlation between antigen-specific proliferation of Lyt 1 + 23- cells and resistance in lethal infections.

Antigen specific T lymphocyte proliferation and Lyt phenotypes of the T lymphocytes were studied in BALB/c and C57BL/6 mice infected with 10(9) M. lepraemurium organisms intravenously. A highly disseminated form of the disease developed to which all mice succumbed by 17 weeks. Maximal antigen-specific T lymphocyte proliferation was detected at 4 weeks after the infection and persisted thereafter even when the mice started to die of the infection. Accessory cells of phagocytic and adherent type did not appear to be a requirement for this proliferation. The T lymphocytes generated during the course of the infection were mostly of the Lyt 1 phenotype. However, there appeared to be no correlation between sensitized Lyt 1 cells capable of antigen-induced T lymphocyte proliferation and protective immunity.

Animals↗

PubMed1994

[Proliferation of pulmonary fibroblasts obtained from rats with bleomycin-induced pulmonary fibrosis and effects of rat rIL-1 alpha on this proliferation].

To clarify the mechanism of pulmonary fibrosis, the growth rate of fibroblasts obtained from bleomycin (BLM)-treated rats was compared with that of fibroblasts obtained from control rats. Proliferation of fibroblasts obtained from rats at 4 days after BLM instillation (BRF) was significantly more rapid than that of fibroblasts obtained from rats at 4 days after saline instillation (CRF), as assessed by cell counting and 3H-TdR incorporation. CRF and BRF were separated by the method of discontinuous Percoll gradients. Three fibroblast fractions of specific gravity (S.G.), S.G. < 1.036, 1.036 < or = S.G. < 1.050, 1.050 < or = S.G. < 1.062, were obtained. Percentages of the densest fibroblast fraction were 46.2 +/- 5.2 in BRF and 6.4 +/- 2.8 in CRF. The densest fibroblasts in BRF proliferated more rapidly than the least dense fibroblasts. Rat rIL-1 alpha suppressed the proliferation of CRF and BRF, dose dependently. These results suggest that an increase in the densest fibroblasts in the lung might correlate with BLM-induced pulmonary fibrosis and that IL-1 alpha suppresses the proliferation of pulmonary fibroblasts.

Animals↗

PubMed1995

A single amino acid change in the mouse peroxisome proliferator-activated receptor alpha alters transcriptional responses to peroxisome proliferators.

The mouse peroxisome proliferator-activated receptor alpha (mP-PAR alpha) can activate transcription from the CYP4A6 promoter in transient cotransfection experiments in the absence (intrinsic transactivation) or presence of added peroxisome proliferator. However, mPPAR alpha-G, in which glycine is substituted for Glu282, exhibits very low intrinsic transactivation and responds fully to added peroxisome proliferators. The two receptors, when expressed in COS-1 cells, are nuclear in localization, are expressed at similar levels, have similar stability, and bind DNA in vitro with similar efficiency. The phenotypic difference in intrinsic transactivation is not altered by overexpression of the human retinoid X receptor alpha. The mPPAR alpha-G mutant receptor displays a higher EC50 for pirinixic acid and for 5,8,11,14-eicosatetraynoic acid than the wild-type PPAR alpha. This difference in the apparent EC50 value is independent of the cell lines used and indicates that the Glu282 to glycine substitution alters the response of mPPAR alpha to peroxisome proliferators. The EC50 values obtained for each receptor with the CYP4A6 reporter construct are lower than those for a reporter derived from the acyl-CoA oxidase gene. In general, an inverse relation is evident between the apparent EC50 values and the extent of intrinsic transactivation observed. The difference in intrinsic transactivation may reflect the presence of an endogenous activator at a concentration that is not sufficient to activate the mPPAR alpha-G but that is sufficient to effect the intrinsic transactivation seen for the wild-type mPPAR alpha.

Acyl-CoA Oxidase↗

PubMed1999

The prognostic significance of proliferation-associated nucleolar protein p120 expression in prostate adenocarcinoma: a comparison with cyclins A and B1, Ki-67, proliferating cell nuclear antigen, and p34cdc2.

BACKGROUND: In this study, the authors evaluated the prognostic significance of the expression of nucleolar antigen p120, along with other cell proliferation-associated proteins, in prostate adenocarcinomas (PACs) and compared the results with previously reported data on p34cdc2 cyclin-dependent kinase (p34 cdk). METHODS: Archival sections from 132 PACs were immunostained with monoclonal antibodies against p120, cyclin A, cyclin B1, Ki-67, and proliferating cell nuclear antigen (PCNA). The DNA content of each tumor was determined by the Feulgen method using image analysis. The immunohistochemistry (IHC) results were correlated with tumor grade, stage, margin positivity, metastasis, ploidy, and postsurgical disease recurrence. RESULTS: The overall positivity for the various proteins follows: p120, 36%; cyclin A, 35%; cyclin B1, 43%; Ki-67, 46%; and PCNA, 32%. p120 correlated with grade (P = 0.004), stage (P = 0.01), ploidy (P = 0.02), margin positivity (P = 0.03), and metastasis (P = 0.004). Cyclin B1 correlated with ploidy (P = 0.04) and grade (P = 0.05), Ki-67 with grade (P = 0.02) and margins (P = 0.03), and PCNA with grade (P = 0.01). Significant coexpression among these proteins was noted, as was a significant association between the expression of these markers and that previously reported for p34 cdk. In univariate analysis, p120 (P = 0.01), cyclin A (P = 0.01) and p34 cdk (P = 0.002) correlated with disease recurrence. In multivariate analysis of all these proteins, only p34 cdk independently predicted postsurgical recurrence (P = 0.05). CONCLUSIONS: Nucleolar antigen p120 expression appears to be an additional marker of aggressiveness in PACs. The significant coexpression of the various cell cycle regulatory proteins support their collective role in tumor cell proliferation, with p34 cdk positivity being an independent predictor of postsurgical recurrence.

Adenocarcinoma↗

PubMed1997

Inhibition of rheumatoid synovial fibroblast proliferation by antisense oligonucleotides targeting proliferating cell nuclear antigen messenger RNA.

OBJECTIVE: To evaluate the feasibility of antisense oligonucleotides as therapeutic agents to inhibit synovial cell growth in rheumatoid arthritis (RA). METHODS: Fibroblast-like cells established from RA synovium were stimulated with interleukin-1beta (IL-1beta) and treated with antisense or sense oligonucleotides targeting proliferating cell nuclear antigen (PCNA) messenger RNA (mRNA). Proliferation of these cells was determined by 3H-thymidine incorporation. Effects of antisense oligonucleotides on the expression of mRNA and protein were evaluated by reverse transcriptase-polymerase chain reaction and immunohistochemical staining, respectively. RESULTS: Antisense oligonucleotides targeting PCNA inhibited IL-1-stimulated fibroblast proliferation, whereas sense oligonucleotides had no effect. Both mRNA and protein levels of PCNA were suppressed in the cells treated with antisense oligonucleotides, indicating that the antiproliferative effect was occurring through an antisense mechanism. CONCLUSION: These results suggest that antisense strategies designed to suppress PCNA expression have potential use as therapeutic agents for RA.

Arthritis, Rheumatoid↗

PubMed1990

Proliferating cell nuclear antigen (PCNA) immunolocalization in paraffin sections: an index of cell proliferation with evidence of deregulated expression in some neoplasms.

Proliferating cell nuclear antigen (PCNA) is a 36 kD nuclear protein associated with the cell cycle. A monoclonal antibody, PC10, that recognizes a fixation and processing resistant epitope has been used to investigate its tissue distribution. Nuclear PCNA immunoreactivity is found in the proliferative compartment of normal tissues. PCNA immunoreactivity is induced in lectin stimulated peripheral blood mononuclear cells in parallel with bromodeoxyuridine incorporation and the number of cells with PCNA immunoreactivity is reduced by induction of differentiation in HL60 cells. In non-Hodgkin's lymphomas a linear relation between Ki67 and PCNA staining was demonstrated. These data suggest that in normal tissues and lymphoid neoplasms, PCNA immunolocalization can be used as an index of cell proliferation. However, in some forms of neoplasia, including breast and gastric cancer and in vitro cell lines, the simple relation between PCNA expression and cell proliferation is lost. In some breast and pancreatic tumours there is apparent deregulation of PCNA with increased expression in tissues adjacent to the tumours. The over-expression in some tumours and in adjacent morphologically normal tissue may represent autocrine or paracrine growth factor influence on PCNA gene expression.

Adult↗

PubMed2001

Mouse hepatocyte response to peroxisome proliferators: dependency on hepatic nonparenchymal cells and peroxisome proliferator activated receptor alpha (PPARalpha).

Peroxisome proliferators (PPs) are rodent nongenotoxic hepatocarcinogens that induce peroxisome proliferation and DNA synthesis, and suppress apoptosis in rodent hepatocytes. PPs act through the PP-activated receptor alpha (PPARalpha); tumour necrosis factor alpha (TNFalpha) and hepatic nonparenchymal cells (NPCs), the major source of TNF alpha in the liver, have also been implicated in mediating the rodent hepatic response to PPs. Here we investigate the interaction between PPARalpha and NPCs in regulating the response to PPs. Using normal hepatocyte cultures containing around 20% NPCs, the PP nafenopin (50 microM) induced DNA synthesis and suppressed transforming growth factor beta1-induced apoptosis. However, when the NPCs were removed by differential centrifugation, nafenopin did not induce DNA synthesis or suppress apoptosis in the pure hepatocytes. Reconstitution of the normal hepatocyte cultures by mixing together the pure hepatocytes and the previously separated NPCs in the same proportions as the original cell preparation (17.7+/-8.7% NPCs) restored the response to nafenopin. Interestingly, nafenopin was still able to induce beta-oxidation in the pure hepatocyte cultures, consistent with NPCs being required for PP-induced growth but not for peroxisome proliferation. Next, we evaluated the role of PPARalpha in the hepatocyte dependency upon NPCs. Interestingly, NPCs isolated from PPARalpha-null mice, like those isolated from the wild-type NPCs, restored the hepatocyte response to nafenopin. However, as expected, PPARalpha-null hepatocytes remained non-responsive to PPs, irrespective of the genotype of the added NPCs. These data support a role for NPCs in facilitating a response of hepatocytes to PPs that is ultimately dependent on the presence of PPARalpha in the hepatocyte.

Animals↗

PubMed1992

Reactive proliferation of astrocytes studied by immunohistochemistry for proliferating cell nuclear antigen.

Astrocyte proliferation in the stab-wounded cerebral cortex of mice was studied using double immunohistochemistry for proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GFAP). The number of GFAP-positive astrocytes increased markedly from day 0.5 to day 3 after stab wounding. Some GFAP-positive astrocytes in the immediate vicinity of the wound were found to be positive for PCNA. However, the maximum number of these double positive astrocytes was only 5-6% of the number of GFAP-positive astrocytes. This maximum value was observed on days 2.5 and 3. The present study revealed that astrocytes are able to reactively express PCNA, an intrinsic marker of DNA replication. On the other hand, it is suggested that the proliferation of astrocytes in the wounded cerebral cortex is limited, in contrast with their marked reactive up-regulation of GFAP.

Animals↗

PubMed1992

Epithelial proliferation in Barrett's esophagus by proliferating cell nuclear antigen immunolocalization.

Proliferating cell nuclear antigen (PCNA) is an auxiliary protein to DNA polymerase delta and is an absolute requirement for cellular proliferation. Specialized-type Barrett's columnar-lined esophagus (CLE) is associated with adenocarcinomatous change. In the present study, the cellular proliferation of three histological types of CLE was assessed by semiquantitative evaluation of PCNA immunolocalization in 93 biopsy specimens from 45 patients using the murine monoclonal PC10. Statistical comparison was performed by the Mann-Whitney U test. Luminal surface cell labeling was uncommon in all histological types other than specialized CLE where 25 of the 43 biopsy specimens had at least occasional luminal surface cell labeling. Mean crypt labeling score of 4.06 for specialized type exceeded that for junctional (mean, 3.12; P < 0.001) and fundic types (mean, 1.6; P < 0.001). Gland cell PCNA staining scores for specialized-type CLE (mean, 3.18) exceeded that of junctional (mean, 1.97; P < 0.001) and fundic (mean, 1.04; P < 0.001). Summated PCNA scores for specialized-type, mean of 8.29, exceeded junctional mean score of 5.45 (P < 0.001) and fundic mean score of 2.76 (P < 0.001). PCNA immunolocalization reveals a high proportion of cells in cycle in the specialized-type CLE and expansion of the proliferative compartment, which may explain the association of specialized-type CLE with malignancy.

Antibodies, Monoclonal↗

PubMed1993

DNA hypomethylation of proliferating cell nuclear antigen gene in human hepatocellular carcinoma is not due to cell proliferation.

Proliferating cell nuclear antigen (PCNA) gene expresses preferentially in proliferative cells or tissues. The levels of PCNA mRNA are very low in livers of adult mammals. Expression of PCNA gene in hepatocellular carcinoma tissues was, however, elevated; and 5'-CCGG-3' sequences of the gene in neoplastic tissue were less methylated. Such DNA hypomethylation was concluded, on the basis of two observations, not to be due to the cell proliferation in hepatoma tissues. First, while the expression of PCNA was increased during serum-stimulation of quiescent Hep G2 cells, the DNA methylation pattern of PCNA gene remained unchanged. Second, in rat liver regeneration, the PCNA mRNA level rose and declined, but the DNA methylation status of PCNA gene was unaltered. Therefore, the DNA hypomethylation of the PCNA gene found in hepatocellular carcinoma was not due to cell proliferation, but a possible consequence of cell transformation.

Animals↗

PubMed2005

Proliferation markers in the adult rodent brain: bromodeoxyuridine and proliferating cell nuclear antigen.

The rostral migratory stream is one of the few regions of the adult mammalian central nervous system in which cellular migration and proliferation have been described. Most rostral migratory stream cells divide rapidly and hence different proliferation markers have been employed to identify them. Nitrogen base substitutes, such as tritiated thymidine or 5-bromo-2'-deoxyuridine (BrdU), together with endogenous molecules, such as Proliferating Cell Nuclear Antigen (PCNA), are the cell cycle markers most widely employed. Protocols for BrdU and PCNA localization are both plentiful and diverse, but to date no optimized protocol for obtaining trustworthy double staining of both markers has been described. In this work, we propose optimized protocols for achieving both single staining and the joint detection of BrdU and PCNA in the rodent brain using double-immunofluorescence procedures. The double labeling described allows the discrimination of different cell cycle stages in migratory cells from the mouse brain.

Animals↗

PubMed2005

Pivotal role of peroxisome proliferator-activated receptor gamma (PPARgamma) in regulation of erythroid progenitor cell proliferation and differentiation.

OBJECTIVE: The aim of this study was to reveal the role of peroxisome proliferator-activated receptor gamma (PPARgamma) in erythropoiesis. METHODS: The effects of PPARgamma ligands on cellular proliferation and differentiation were investigated in erythroid colony-forming cells (ECFCs) purified from human peripheral blood. RESULTS: RT-PCR analysis revealed that PPARgamma mRNA is expressed in ECFCs. Synthetic PPARgamma ligands, troglitazone or pioglitazone, suppressed cellular proliferation without inducing apoptosis and delayed maturation of ECFCs, as determined by flow cytometry. The delay in erythroid maturation by troglitazone was confirmed by the down-regulation of gamma-globin, beta-globin and GATA-1 mRNA, and the maintenance of GATA-2 mRNA. CONCLUSIONS: Our results suggest that PPARgamma modulates the differentiation process of erythroid progenitor cells, and plays a crucial role in regulating the balance of hematopoiesis.

Antineoplastic Agents↗

PubMed2001

Further evidence for the involvement of inhibition of cell proliferation and development in thymic and splenic atrophy induced by the peroxisome proliferator perfluoroctanoic acid in mice.

We recently demonstrated that severe thymic and splenic atrophy occur upon dietary treatment of mice with potent peroxisome proliferators (PPs), e.g. perfluorooctanoic acid (PFOA), WY-14,643, nafenopin, and di(2-ethylhexyl)phthalate (DEHP). In the present study, we investigated this phenomenon further employing a relative inert PP, PFOA. Comparison of the dose-dependencies and time-courses indicated that the peroxisome proliferative effect occurred prior to atrophy of both the thymus and spleen. However, following withdrawal of PFOA from the diet, the weight of the thymus and spleen rapidly returned to normal within 10 and 5 days, respectively, in contrast to the more persistent peroxisome proliferation. Furthermore, the changes in thymus and spleen weight upon PFOA treatment and the following withdrawal from diet paralleled the changes in total thymocyte and splenocyte counts, respectively. It was found previously that the decreases in the thymocyte populations present in the S and G2/M phases, as well as in the number of CD4+CD8+ cells upon PFOA treatment, were the most dramatic, perhaps reflecting inhibition of thymocyte proliferation in connection with thymocyte development. Here, the recovery of thymocytes began with increases in the populations in these same phases of the cell cycle, with CD4+CD8+ cells recovering most rapidly, lending further support to our previous hypothesis. The possible relationship of these immunotoxic effects of PPs to the changes they cause in fatty acid metabolism is discussed.

Animals↗

PubMed1994

Comparison of villous trophoblast proliferation rate in hydatidiform mole and non-molar abortion by assessment of proliferating cell nuclear antigen expression.

This study examines the proliferative activity of trophoblast in hydatidiform mole, non-molar hydropic abortion and non-molar spontaneous abortion. Nine cases of complete mole, 10 cases of partial mole, eight cases of non-molar hydropic abortion and six cases of non-hydropic second trimester abortion were examined by routine histopathology and the rate of cell proliferation was assessed by immunoreactivity for proliferating cell nuclear antigen (PCNA). Hydropic abortion showed a significantly lower PCNA index than complete mole and partial mole. There was no significant difference in PCNA index between partial mole and non-hydropic abortion. The trophoblast of partial hydatidiform mole demonstrates significant cell proliferation but this, although higher than that of hydropic abortion, is no higher than that of non-hydropic abortion of a similar gestational age. The role of partial mole as a precursor of persistent gestational trophoblastis disease remains unclear.

Abortion, Spontaneous↗