Colonic cell proliferation and growth fraction in young,adult and old rats

Colonic epithelial proliferation was investigated in three groups of rats, aged 3, 60 and 121 weeks. As reported in previous work, the crypts were markedly longer in the young rats, and the number of labelled cells per crypt was significantly greater. There was an upward movement of the marker positions derived from the distribution of labelled cells within the crypt of the young rats. This was a consequence of the increased crypt length, so that the growth fraction, as expressed as a percentage of crypt length, was the same. The proliferative changes between the young rats and the other aged rats were therefore effected by altering the size of the crypts, while maintaining the kinetic organisation. There was no evidence of any proliferative changes or changes in the growth fraction when the colons of the old rats were compared with those of the 60 week old rats.     

Up-regulation of CHAF1A,a poor prognostic factor,facilitates cell proliferation of colon cancer

Deregulation of chromatin assembly factor 1, p150 subunit A (CHAF1A) has recently been reported to be involved in the development of some cancer types. In this study, we identified that the frequency of positive CHAF1A staining in primary tumor mucosa (45.8%, 93 of 203 samples) was significantly elevated compared to that in paired normal mucosa (18.7%, 38 of 203 samples). The increased expression was strongly associated with cancer stage, tumor invasion, and histological grade. The five-year survival rate of patients with CHAF1A-positive tumors was remarkably lower than that of patients with CHAF1A-negative tumors. Colon cancer cells with CHAF1A knockdown exhibited decreased cell growth index, reduction in colony formation ability, elevated cell apoptosis rate as well as impaired colon tumorigenicity in nude mice. Hence, CHAF1A upregulation functions as a poor prognostic indicator of colon cancer, potentially contributing to its progression by mediating cancer cell proliferation.     

PSF3 marks malignant colon cancer and has a role in cancer cell proliferation

PSF3 (partner of Sld five 3) is a member of the tetrameric complex termed GINS, composed of SLD5, PSF1, PSF2, and PSF3, and well-conserved evolutionarily. Previous studies suggested that some GINS complex members are upregulated in cancer, but PSF3 expression in colon carcinoma has not been investigated. Here, we established a mouse anti-PSF3 antibody, and examined PSF3 expression in human colon carcinoma cell lines and colon carcinoma specimens. We found that PSF3 is expressed in the crypt region in normal colonic mucosa and that many PSF3-positive cells co-expressed Ki-67. This suggests that PSF3-positivity of normal mucosa is associated with cell proliferation. Expression of the PSF3 protein was greater in carcinoma compared with the adjacent normal mucosa, and even stronger in high-grade malignancies, suggesting that it may be associated with colon cancer progression. PSF3 gene knock-down in human colon carcinoma cell lines resulted in growth inhibition characterized by delayed S-phase progression. These results suggest that PSF3 is a potential biomarker for diagnosis of progression in colon cancer and could be a new target for cancer therapy.     

Antizyme1基因转染对K562细胞增殖与凋亡的影响

研究鸟氨酸脱羧酶抗酶蛋白对人红白血病K562细胞增殖、三氧化二砷（ As2O3）诱导凋亡时的影响。方法: 定点突变技术构建缺失frameshift位点的pEGFP-N1-AZ1-mutation重组表达载体。脂质体法转染K562细胞,通过G418筛选获得稳定表达antizyme1的K562pAZ1m细胞系。采用不同浓度的As2O3处理细胞,通过MTT法检测细胞增殖,流式细胞术分析细胞周期及凋亡变化。并通过RT-PCR方法检测antiyme1转染对cyclin D1和survivin基因表达的影响。结果：获得稳定表达antizyme1的K562-AZ1m细胞株后,其增殖能力明显减慢。CyclinD1基因表达降低,细胞主要停滞于G0/G1期。在 As2O3的诱导作用下,细胞凋亡增多,survivin基因表达降低。结论：AZ1基因能够抑制K562细胞增殖,通过对cyclinD1的负调控使细胞周期停滞于G0/G1期。并可能通过下调survivin表达来加强 As2O3对其的诱导凋亡作用     

Inhibition of cyclooxygenase-1 lowers proliferation and induces macroautophagy in colon cancer cells

Evolving evidence supports that cyclooxygenase-1 (COX-1) takes part in colon carcinogenesis. The effects of COX-1 inhibition on colon cancer cells, however, remains obscured. In this study, we demonstrate that COX-1 inhibitor sc-560 inhibited colon cancer cell proliferation with concomitant G₀/G₁-phase cell cycle arrest. The anti-proliferative effect was associated with down-regulation of c-Fos, cyclin E₂ and E₂F-1 and up-regulation of p21^Waf1/Cip1 and p27^Kip1. In addition, sc-560 induced macroautophagy, an emerging mechanism of tumor suppression, as evidenced by the formation of LC3⁺ autophagic vacuoles, enhanced LC3 processing, and the accumulation of acidic vesicular organelles and autolysosomes. In this connection, 3-methyladenine, a Class III phosphoinositide 3-kinase inhibitor, significantly abolished the formation of LC3⁺ autophagic vacuoles and the processing of LC3 induced by sc-560. To conclude, this study reveals the unreported relationship between COX-1 and proliferation/macroautophagy of colon cancer cells.     

The effect of selenium on cell proliferation in liver and colon

Epidemiologic and experimental evidence support a chemoprotective role for selenium (Se) in malignancy. Many mechanisms have been proposed to explain this phenomenon. In this study, the effect of Se intake on proliferation of hepatocytes and normal colonic epithelial cells in rats was determined using autoradiographic analysis of thymidine incorporation into DNA. Hepatocyte proliferation was measured 24 h after partial hepatectomy. Selenium-dosed animals demonstrated a significant reduction in hepatocyte labeling compared to the control group (6.1±2.6 vs 29.2±15.6,p=0.003). However, Se dosing did not affect the thymidine-labeling indices or distribution of labeling in colonic epithelium. Selenium may inhibit cell proliferation when it is the result of an unusually intense stimulus. This finding could explain in part the inhibitory effect of Se in some experimental cancer models. Dr. Tempero is a recipient of a Junior Clinical Faculty Fellowship from the American Cancer Society.     

Effect of an inhibitor of noradrenaline uptake,desipramine, on cell proliferation in the intestinal crypt epithelium

The intestinal mucosa receives an adrenergic innervation for which there is no commonly accepted function. However, in recent years, cell kinetic studies have raised the possibility that this innervation may be an important regulator of crypt cell proliferation. The effects of noradrenaline released from adrenergic nerves is terminated principally by re-uptake of the amine into the nerve and this process can be inhibited by the antidepressant drug, desipramine. In this report desipramine is shown to accelerate crypt cell proliferation in intact, but not in chemically sympathectomized rats, thus adding support to the notion that regulation of crypt cell division is an important function of the sympathetic nervous system.     

The effect of dietary carbohydrate on the rise in plasma glutamate concentrations following oral glutamate ingestion in rats

Plasma glutamate concentrations were examined in male rats following oral intubation of monosodium L-glutamic acid (MSG, 250 mg/kg) soon after ingesting one of several meals differing in carbohydrate content. Intubation of MSG alone produced a 4-fold rise in plasma glutamate that peaked at 15 min, and returned to baseline by 60 min. Red blood cell glutamate concentrations were unchanged. The ingestion of a meal lacking carbohydrate produced a modest attenuation of the post-MSG intubation rise in plasma glutamate concentrations. This attenuating effect increased progressively with the carbohydrate content of the meal (and as the protein content declined, to maintain isocaloric meals), though as little as 5% carbohydrate marked attenuated the plasma glutamate rise. This effect diminished as the time interval between the meal and MSG intubation increased from 1 to 4 hrs. Similar, but not identical effects were noted when meals substituted fat (instead of protein) for carbohydrate. The intubation of MSG alone produced a slight increase in plasma alanine concentrations over the 60-min post-intubation period examined. The ingestion of any of the meals just prior to intubation did not influence this effect. Overall, the results indicate that although the ingestion of carbohydrate can markedly attenuate the rise in plasma glutamate that follows MSG consumption in rats, this effect is also influenced by the other macronutrients present. The absence of notable, meal related changes in plasma alanine suggests that this parameter does not provide a useful indication of gut glutamate transamination.     

The completion of cell proliferation and growth in wheat radicle

The pattern of proliferation and growth of cortical and central metaxylem cells in a radicle and the transitional zone of a wheat embryo was studied during the final stages of embryogenesis. Cell divisions finished nearer the root tip in the central metaxylem than was the case in the cortex. After divisions ceased the cells of both tissues maintained the ability to synthesize DNA and the cells began DNA endoreduplication. The maximal levels of endoreduplication were 4C and 8C in cortical and central metaxylem cells, respectively. As a result of nonsimultaneous cessation of divisions, the metaxylem cells were two or three times longer than cortical cells. The proportion of cells with the maximal DNA content was smaller in the transitional zone than in the radicle. During the final embryonal stages cell growth rate was decreased. It was established that the transition of cells to DNA synthesis was inhibited in all sites of the radicle during the completion of embryogenesis. The cell growth was topped in proximal sites of the radicle. In the division zone the cells which had already begun DNA synthesis were able to complete it and divided. Cell growth stopped simultaneously with completion of proliferation in this zone.     

Involvement of over-expressed BMP4 in pentylenetetrazol kindling-induced cell proliferation in the dentate gyrus of adult rats

The dentate gyrus (DG) of the hippocampus is one of a few regions in the adult mammalian brain characterized by ongoing neurogenesis. Proliferation of neural precursors in the granule cell layer of the DG has been identified in pentylenetetrazol (PTZ) kindling epilepsy model, however, little is known about the molecular mechanism. We previously reported that the expression pattern of bone morphogenetic proteins-4 (BMP4) mRNA in the hippocampus was developmentally regulated and mainly localized in the DG of the adult. To explore the role of BMP4 in epileptic activity, we detected BMP4 expression in the DG during PTZ kindling process and explore its correlation with cell proliferation combined with bromodeoxyuridine (BrdU) labeling technique. We found that dynamic changes in BMP4 level and BrdU labeled cells dependent on the kindling stage of PTZ induced seizure-prone state. The number of BMP4 mRNA-positive cells and BrdU labeled cells reached the top level 1 day after PTZ kindled, then declined to base level 2 months later. Furthermore, there was a significant correlation between increased BMP4 mRNA expression and increased number of BrdU labeled cells. After effectively blocked expression of BMP4 with antisense oligodeoxynucleotides(ASODN), the BrdU labeled cells in the dentate gyrus subgranular zone(DG-SGZ) and hilus were significantly decreased 16d after the first PTZ injection and 1, 3, 7, 14d after kindled respectively. These findings suggest that increased proliferation in the DG of the hippocampus resulted from kindling epilepsy elicited by PTZ maybe be modulated by BMP4 over-expression.     

The influence of cell volume changes on tumour cell proliferation

Ion channels and cell volume control participate in a wide variety of cellular functions, including cell proliferation. According to the pump-leak model or the double Donnan system, the cell volume is constant in physiological medium so long as the cell metabolism and the Na-K pump are not inhibited and the passive Na⁺ permeability is not dramatically increased. At short term, this model has been supported by a large number of experiments made on different cell types. However, at long term, it may be insufficient to describe the volume control because it does not take into account the fact that cells possess a large number of membrane transporters and interconnected volume regulatory mechanisms. In this review, we present recent results indicating that, in physiological conditions, ion channels may have important roles in cell volume control. Furthermore, we emphasize that cell proliferation and volume are phenomenologically correlated. On the basis of the macromolecular crowding theory, the possibility that the cell osmolyte and water content mediates this correlation is discussed.Abbreviations 4-AP 4-aminopyridine - NPPB 5-nitro-2-(3-phenylpropylamino)benzoic acid - TEA tetraethylammonium - TOR target of rapamycin Presented at the Biophysical Society Meeting on Ion channels—from structure to desease held in May 2003, Rennes, France     

Stimulating effect of pentagastrin on cancer cell proliferation kinetics in chemically induced colon cancer in rats

Pharmacological doses of pentagastrin or gastrin are known to stimulate cell proliferation in normal colonic epithelium but the growth-promoting effect of gastrin on colon carcinoma is still controversial. In this study morphological parameters were measured to study the effect of pentagastrin (240 micrograms/kg) on the cell proliferation kinetics in experimental tumours. Colon cancer was produced in rats by weekly injections (20 mg/kg b.wt.) of 1.2-dimethylhydrazine for 24 weeks. Tritiated thymidine was given after administration of pentagastrin or the control solution to the animals. 75% of the animals from the pentagastrin group and 66% of the controls had at least one colon cancer. Autoradiographs of the colonic tumors were performed and the percentage of labeled cells in the cancer cell population was determined after counting 4000 to 16,000 cancer cells per tumor. The labeling index for cancer cells in the pentagastrin-treated group (21.49 +/- 1.76%) was higher (P less than 0.01) than in the control group (14.76 +/- 0.66%). In a second study vincristine sulphate (1 mg/kg) was given to the animals 20 h after administering pentagastrin or the control solution. The percentage of arrested metaphases in the tumours was determined after counting 10,000 to 24,000 cancer cells per histological section. Pentagastrin increased (P less than 0.01) the mean metaphase index by 108% (4.9 +/- 0.44% vs 2.35 +/- 0.32%). These data indicate that cell cycle manipulation of colon cancer is possible with hormonal peptides.     

不同测压方法测试大鼠结肠破裂压

目的比较不同测压方法测试大鼠结肠破裂压的优缺点。方法45只雄性SD大鼠随机等分为手动皮球测压组（H组）、机器测压压力表头描记测试组（MP组）、“实验动物空腔脏器耐压力测试系统”测试组（ME组）。各组大鼠经尾静脉注射麻醉后,切取结肠测试结肠破裂压;大鼠结肠端-端吻合一周后切取各组大鼠结肠吻合口,同法测试吻合口破裂压。结果三种测压方法所测得正常结肠及结肠吻合口破裂压差异无统计学意义（P〉0．05）,但ME组的标准差最小,MP组次之,H组的标准差最大。结论不同测压方法均可应用于大鼠正常结肠和结肠吻合口破裂压测试,但“实验动物空腔脏器耐压力测试系统”使实验更简便、直观,实验结果更客观、精确。     

Caco-2 and LS174T cell lines provide different models for studying mucin expression in colon cancer

To compare the differences in MUC2 and MUC5AC mRNA among four colon cancer cell lines and to identify the best in vitro models for studying mucin expression, quantitative real-time polymerase chain reaction was used to measure the expression of MUC2 and MUC5AC mRNA in Caco-2, HT29, LoVo, and LS174T cell lines. The levels of MUC2 mRNA expression in the four colon cancer cell lines ranked in order of mRNA abundance were: LS174T > LoVo > HT-29 > Caco-2. In contrast to MUC2, the abundances of MUC5AC mRNA were in the order: Caco-2 > HT-29 > LS174T > LoVo. Caco-2 (highest level of MUC5AC mRNA) and LS174T (highest level of MUC2 mRNA) were used to investigate the phenotypes. Morphologically, Caco-2 cells were larger with low electron density mucus-storing vacuoles, many cell surface microvilli, and no obvious intercellular spaces between cells, compared to LS174T cells. The proliferative and invasive capacities of LS174T cells were significantly higher than those of Caco-2 cells. Caco-2 and LS174T cells provide excellent in vitro models for studying mucin expression in colon cancer.     

The effect of an LH pulse on 3H-thymidine incorporation into cultured ovaries of metestrous rats

Summary The effect of an LH pulse on the rate at which ³H-thymidine is incorporated into cultured ovaries of metestrous rats was studied. In comparison to ovaries cultured with tonic LH, an LH pulse (1) rescued follicles from atresia, (2) induced thecal cell proliferation, and (3) increased the rate at which granulosa cells enter mitosis. It is concluded that LH pulses increase follicular growth by first triggering thecal cell proliferation and then inducing mitotic divisions within the granulosa cells of both atretic and non-atretic follicles.     

Sphingomyelin in the suppression of colon tumors: prevention versus intervention

Intestinal cells are regularly exposed to sphingolipid metabolites, i.e., ceramide and sphingoid bases, after hydrolysis of complex sphingolipids from the diet. These metabolites are known regulators of cell growth, differentiation, and death. Non-pharmacological amounts in the diet have been shown to inhibit early stages of chemically induced colon cancer in mice. To distinguish between chemopreventive and chemotherapeutic effects of sphingomyelin supplements, mice were fed sphingomyelin before and after tumor initiation. Both applications drastically reduced tumor formation, without a significant difference among the groups, indicating that sphingolipids are as effective in the chemoprevention of tumors as in early intervention. The normalization of cell proliferation and rate of apoptosis, but not the induction of differentiation, seem to be key players in the suppression of tumor formation by dietary sphingomyelin. This may have implications for the development of a cancer prevention or treatment strategy with sphingolipids as an alternative to conventional drugs.     

The effect of bacterial DNA gyrase inhibitors on DNA synthesis in mammalian mitochondria

Using isolated rat liver mitochondria, which have previously been shown to carry out true replicative DNA synthesis, we have obtained results which are in accord with the presence and functioning of a DNA gyrase in this organelle. The effects of the Escherichia coli DNA gyrase inhibitors, novobiocin, coumermycin, nalidixic acid and oxolinic acid, upon mtDNA replication suggest the involvement of the putative mitochondrial enzyme in various aspects of this process. First, the preferential inhibition of [³H]dATP incorporation into highly supercoiled DNA together with the appearance of labeled, relaxed DNA are consistent with the involvement of a gyrase in the process of generating negative supercoils in mature mtDNA. Second, the overall depression of incorporation of labeled dATP into mtDNA, including the reduction of radioactivity incorporated into replicative intermediates, suggests a ‘swivelase’ role for the putative gyrase, and this hypothesis is further supported by results obtained on sucrose gradient centrifugation of heat-denatured, d-loop mtDNA. Here, the synthesis of the completed clean circles is inhibited while 9 S initiator strand synthesis is not, suggesting that chain elongation is blocked by the gyrase inhibitors.     

Consequences of the salvage of purine compounds on the proliferation of rat T-lymphocytes with normal or inhibited purine de novo synthesis

We studied the ability of purine compounds to restore the proliferation of concanavalin-A-stimulated rat T-lymphocytes under conditions of purine de novo synthesis inhibition and, on the other hand, the inhibition by purine nucleosides of the response of these cells to a mitogenic stimulation under conditions of normal purine de novo synthesis. The use of 50 μM azaserine, a potent inhibitor of purine de novo synthesis, allowed us to define the physiologically active salvage pathways of purine bases, ribo- and deoxyribonucleosides in concanavalin-A-stimulated rat T-lymphocytes. Except for guanylic compounds, all purines completely restored cell proliferation at a concentration of 50 μM. Guanine, guanosine and 2′-deoxyguanosine at concentrations up to 500 μM did not allow us to restore more than 50% of the cell proliferation. In conditions of normal purine de novo synthesis, the addition of 1000 μM adenine, adenosine, 2′-deoxyadenosine or 100 μM 2′-deoxyguanosine inhibited rat T-lymphocyte proliferation. The differences between the degree of inhibition of cell proliferation could be explained only in part by the differences between the capacities of salvage of these compounds. Furthermore, the fact that 2′-deoxyguanosine toxicity was dependent and 2′-deoxyadenosine toxicity independent on the activation state of the cells provided more evidence that the biochemical mechanisms of inhibition of cell proliferation should be different for these two nucleosides.     

Scleractinian coral cell proliferation is reduced in primary culture of suspended multicellular aggregates compared to polyps

Cell cultures from reef-building scleractinian corals are being developed to study the response of these ecologically important organisms to environmental stress and diseases. Despite the importance of cell division to support propagation, cell proliferation in polyps and in vitro is under-investigated. In this study, suspended multicellular aggregates (tissue balls) were obtained after collagenase dissociation of Pocillopora damicornis coral, with varying yields between enzyme types and brands. Ultrastructure and cell type distribution were characterized in the tissue balls (TBs) compared to the polyp. Morphological evidence of cellular metabolic activity in their ciliated cortex and autophagy in their central mass suggests involvement of active tissue reorganization processes. DNA synthesis was evaluated in the forming multicellular aggregates and in the four cell layers of the polyp, using BrdU labeling of nuclei over a 24 h period. The distribution of BrdU-labeled coral cells was spatially heterogeneous and their proportion was very low in tissue balls (0.2 ± 0.1 %), indicating that suspended multicellular aggregate formation does not involve significant cell division. In polyps, DNA synthesis was significantly lower in the calicoderm (<1 %) compared to both oral and aboral gastroderm (about 10 %) and to the pseudostratified oral epithelium (15–25 % at tip of tentacle). DNA synthesis in the endosymbiotic dinoflagellates dropped in the forming tissue balls (2.7 ± 1.2 %) compared to the polyp (14 ± 3.4 %) where it was not different from the host gastroderm (10.3 ± 1.2 %). A transient (24 h) increase was observed in the cell-specific density of dinoflagellates in individually dissociated coral cell cultures. These results suggest disruption of coral cell proliferation processes upon establishment in primary culture.     

The effect of a high carbohydrate diet on running performance during a 30-km treadmill time trial

The purpose of the present study was to examine the influence of a high carbohydrate diet on running performances during a 30-km treadmill time trial. Eighteen runners (12 men and 6 women) took part in this study and completed a 30-km time trial on a level treadmill without modifying their food intake (trial 1). The runners were then randomly assigned to a control or a carbohydrate (CHO) group. The CHO group supplemented their normal diets with additional carbohydrate in the form of confectionery products during the 7 days before trial 2; the control group matched the increased energy intake of the CHO group by consuming additional fat and protein. The mean (SEM) carbohydrate intake of both groups was 334 (22) g before trial 1, after which the CHO group consumed 566 (29) g.day-1 for the first 3 days and 452 (26) g.day-1 for the remaining 4 days of recovery. Although there was no overall difference between the performance times for the two groups during trial 2, the CHO group ran faster during the last 5 km of trial 2 than during trial 1 [3.64 (0.24) m.s-1 vs 3.44 (0.26) m.s-1; P less than 0.05]. Furthermore, the 6 men in the CHO group ran the 30 km faster after carbohydrate loading [131.0 (5.4) min vs 127.4 (4.9) min; P less than 0.05], whereas there was no such improvement in times of the men in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)