Altered Cell Turnover Research Articles

Functional consequences of the first reported mutations of the proto-oncogene PTTG1IP/PBF.

Pituitary tumor-transforming gene 1-binding factor (PTTG1IP; PBF) is a multifunctional glycoprotein, which is overexpressed in a wide range of tumours, and significantly associated with poorer oncological outcomes, such as early tumour recurrence, distant metastasis, extramural vascular invasion and decreased disease-specific survival. PBF transforms NIH 3T3 fibroblasts and induces tumours in nude mice, while mice harbouring transgenic thyroidal PBF expression show hyperplasia and macrofollicular lesions. Our assumption that PBF becomes an oncogene purely through increased expression has been challenged by the recent report of mutations in PBF within the Catalogue of Somatic Mutations in Cancer (COSMIC) database. We therefore sought to determine whether the first 10 PBF missense substitutions in human cancer might be oncogenic. Anisomycin half-life studies revealed that most mutations were associated with reduced protein stability compared to wild-type (WT) PBF. Proliferation assays narrowed our interest to two mutational events which significantly altered cell turnover: C51R and R140W. C51R was mainly confined to the endoplasmic reticulum while R140W was apparent in the Golgi apparatus. Both C51R and R140W lost the capacity to induce cellular migration and significantly reduced cell invasion. Colony formation and soft agar assays demonstrated that, in contrast to WT PBF, both mutants were unable to elicit significant colony formation or anchorage-independent growth. However, C51R and R140W retained the ability to repress radioiodide uptake, a functional hallmark of PBF. Our data reveal new insight into PBF function and confirm that, rather than being oncogenic, mutations in PBF are likely to be passenger effects, with overexpression of PBF the more important aetiological event in human cancer.

Tu1734 A Role of iRhom2 for the Secretion of TNF-α in Inflammatory Bowel Disease

hypoxia, altered cell turnover with increased cell division and increased permeability to FD4. CS exposure led to increases in TNF-α, IFN-γ and TGF-β transcript in colon tissue. Increased mucosal vasculature was accompanied and preceded by induction of, VEGF and iNOS transcript; genes related to angiogenesis and vasodilation. On exposure to TNBS, smoked mice developed a more severe and aggressive colitis. Conclusions: In CS exposed mice, reduced tissue oxygen perfusion drives intestinal tissue hypoxia, leading to ischemic epithelial damage and permeability accompanied by neovascularisation and vasodilation. Combined, these pathologies may increase mucosal exposure to luminal bacteria, driving inflammation as measured by increased TNF-α, IFN-γ and TGF-β transcript in colon tissue. This model may represent the mechanism by which cigarette smokers are at increased risk and severity to gut mucosal inflammation associated with CD.

Biological responses of juvenile European sea bass (Dicentrarchus labrax) exposed to contaminated sediments

Multiple anthropogenic activities present along coastal environments may affect the health status of aquatic ecosystems. In this study, specimens of European sea bass (Dicentrarchus labrax) were exposed for 30 days to highly contaminated sediment collected from the industrial area between Augusta and Priolo (Syracuse, Italy), defined as the most mercury polluted site in the Mediterranean. The aim was to evaluate the responses of juvenile D. labrax to highly contaminated sediments, particularly enriched in Hg, in order to enhance the scarce knowledge on the potential compensatory mechanisms developed by organisms under severe stress conditions. Apoptotic and proliferative activities [cell turnover: Proliferating Cell Nuclear Antigen (PCNA) and FAS Ligand (FasL)], onset of hypoxic condition [hypoxia: Hypoxia Inducibile Factor-1α (HIF-1α)], and changes in the neuroendocrine control mechanisms [neurotransmission: Tyrosine Hydroxylase (TH), Choline Acetyltransferase (ChAT), Acetylcholinesterase (AChE), 5-Hydroxytryptamine (5-HT) and 5-Hydroxytryptamine receptor 3 (5-HT3)] were investigated in sea bass gill tissues. In the specimens exposed to the polluted sediment, the occurrence of altered cell turnover may result in impaired gas exchange that leads to a condition of “functional hypoxia”. Changes in neurotransmission pathways were also observed, suggesting a remodeling process as an adaptive response to increase the O2-carrying capacity and restore the normal physiological conditions of the gills. Overall, these findings demonstrated that although chronic exposure to heavy metal polluted sediments alters the functioning of both the nervous and endocrine systems, as well as plasticity of the gill epithelium, fish are able to trigger a series of physiological adjustments or adaptations interfering with specific neuroendocrine control mechanisms that enable their long-term survival.

Abstract LB-182: Effects of methyl donor status on intestinal tumorigenesis in ApcMin/+ mice

Abstract The goal of the present study is to determine the effects of folate deficiency on intestinal tumorigenesis in ApcMin/+ mice, a widely used animal model for human familial adenomatous polyposis (FAP). Since folate plays an important role in maintaining methyl donor status, dietary folate levels were reduced in combination with a panel of methyl donors, including choline, methionine and vitamin B12. Although the impact of folate on colorectal cancer (CRC) has been studied extensively, its role in cancer chemoprevention remains controversial. For example, folate supplementation has been widely discussed as a strategy for lowering cancer incidence. However, excess folate has also been associated with increased cancer risk. The following studies were designed to evaluate the effects of folate deficiency on intestinal tumorigenesis in ApcMin/+ mice. In Study 1, methyl donor sufficient diet (MDS) and methyl donor deficient diet (MDD) were fed to mice, beginning at either 5 or 10 weeks of age. Intestinal tumors were evaluated at 16 weeks of age. MDD diet suppressed intestinal tumor formation in ApcMin/+ mice by ∼80% when started at 5 weeks of age. Importantly, the protective effect was lost when the MDD diet was started at 10 weeks of age, indicating an important time-dependency on cancer suppression. Gene expression profiling of normal colonic mucosa after 11 weeks on MDD diet identified the most significantly down-regulated genes related to immune response and inflammation, data that are consistent with a recently published human colon expression profiling study (Protiva et al., 2011). The cancer suppression, however, was associated with reduced food intake and lowered body weight gain (up to 40%) throughout the experimental period. To control for this effect, Study 2 was performed in which ApcMin/+ mice were pair-fed with either methyl donor sufficient (MDS) or methyl donor deficient (MDD) diet, beginning at 5 weeks of age for a total of 11 weeks. A third group received MDS ad libitum. At 16 weeks of age, intestinal tumor formation was significantly reduced (54%, p<0.001) in the caloric-restricted MDS group. In the MDD group, however, tumor suppression was almost complete (∼96%, p<0.001). Associated with tumor protection were increased numbers of apoptotic cells within the villous epithelium of the small intestine, with a concomitant reduction in cell proliferation assessed by Ki-67 and Phospho-histone H3 (pHH3). While cancer protection by methyl donor deficiency is partially dependent on reduced caloric intake, additional mechanisms dependent on altered cell turnover must be invoked to explain these results. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-182. doi:1538-7445.AM2012-LB-182

Histological and immunohistochemical evaluation of new epithelium after removal of oral leukoplakia with Nd:YAG laser treatment

Laser excision has been used with increasing success to treat oral leukoplakia. The aim of the present study was to evaluate whether clinical healing of a leukoplakia after laser surgery is associated with a normal functional status of the new epithelium and whether pathological alterations in these parameters are related to the risk of local recurrence. The study population consisted of 13 consecutive patients with oral leukoplakia in which clinical healing was achieved after laser therapy using an Nd:YAG laser (Model 6000, Laser Sonics, Cooper Laser Sonics). At the end of the therapy, all patients underwent a second biopsy of the clinically healthy tissue. Epithelial cell turnover was evaluated before and after laser surgery by Ki67 protein expression, and positive staining of more than 20% was considered abnormal. All patients were followed on a monthly basis. Eight patients had abnormally high Ki67 values before laser therapy (mean 27.4 ± 6.2%), but the levels decreased significantly after treatment (17.6 ± 8.5%; t = 2.6, p < 0.05). High Ki67 values persisted in three patients, and local recurrences in the new epithelium was observed in two of these patients. Kaplan-Meier statistics showed that the between-group difference was statistically significant (Chi square 7.3; p < 0.01). In conclusion, this is the first prospective study to show that clinical healing of leukoplakia treated by laser surgery may be accompanied by altered cell turnover in 20% of the cases. Ki67, as a marker of proliferative status, may be a prognostic indicator in the mucosa replacing the lesion.

Intra-uterine growth restriction is associated with increased apoptosis and altered expression of proteins in the p53 pathway in villous trophoblast

Intrauterine growth restriction (IUGR) affects 3-8% of pregnancies and is associated with altered cell turnover in the villous trophoblast, an essential functional cell type of the human placenta. The intrinsic pathway of apoptosis, particularly p53, is important in regulating placental cell turnover in response to damage. We hypothesised that expression of proteins in the p53 pathway in placental tissue would be altered in IUGR. Expression of constituents of the p53 pathway was assessed using real-time PCR, Western blotting and immunohistochemistry. p53 mRNA and protein expression was increased in IUGR, which localised to the syncytiotrophoblast. Similar changes were noted in p21 and Bax expression. There was no change in the expression of Mdm2, Bak and Bcl-2. The association between altered trophoblast cell turnover in IUGR and increased p53 expression is reminiscent of that following exposure to hypoxia. These observations provide further insight into the potential pathogenesis of IUGR. Further research is required to elicit the role and interactions of p53 and its place in the pathogenesis of IUGR.

Extracellular matrix overproduction vs. altered cell turnover in glomeruli from experimental diabetic rats

Extracellular matrix overproduction vs. altered cell turnover in glomeruli from experimental diabetic rats

Prenatal exposure to pesticides disrupts testicular histoarchitecture and alters testosterone levels in male Caiman latirostris

The increased use of agrochemical pesticides, such as atrazine (ATZ) and endosulfan (END), may have a significant impact on ecosystem health and biodiversity. The aim of this study was to investigate the consequences of in ovum exposure to ATZ and END on Caiman latirostris gonadal histo-functional features. Caiman eggs were collected from environmentally pristine areas and incubated in controlled conditions at male producing temperature (33 °C). At stage 20 of embryonic development, the sensitive stage for gonadal sex determination, eggs were exposed to one dose of either END or ATZ. Gonadal histo-morphology was examined in caiman hatchlings and serum levels of testosterone were measured. Regardless of treatment condition, all eggs incubated at 33 °C resulted in male hatchlings. Tortuous seminiferous tubules with increased perimeter, disrupted distribution of peritubular myoid cells (desmin positive), and emptied tubular lumens characterized the testes of pesticide-exposed caiman. An imbalance between proliferative activity and cell death was observed in the testes of caiman exposed to the higher doses of END, mainly due to a high frequency of apoptosis in intratubular cells. This altered cell turnover was associated with decreased testosterone levels. Prenatal exposure to only one dose of END and ATZ disrupted neonatal male gonadal histo-functional features. Alterations described here could have detrimental effects on the sexual maturation of the caiman and, ultimately, on the success of male caiman reproduction.

Does altered oxygenation or reactive oxygen species alter cell turnover of BeWo choriocarcinoma cells?

This study assessed the effect of 20 and 6% ambient oxygen (O 2) or 5–50 μmol/l hydrogen peroxide (H 2O 2) on apoptosis, necrosis, proliferation and fusion of BeWo cells. The expression of p53, Mdm2 and Bax was assessed by western blotting. Apoptosis was increased in cells cultured in 6% O 2 tension and 50 μmol/l H 2O 2 ( P < 0.05, P < 0.01 by ADP:ATP ratio). In the same conditions, cell viability as estimated by the MTT assay was decreased (6% O 2 P < 0.01, 50 μmol/l H 2O 2 P < 0.05). Human chorionic gonadotrophin secretion was decreased by culture in 6%O 2 and 50 μmol/l H 2O 2 ( P < 0.05). Cell fusion was also decreased by treatment with 50 μmol/l H 2O 2 ( P < 0.05). Treatment with 50 μmol/l H 2O 2 was associated with increased expression of p53 and decreased expression of Mdm2 ( P < 0.05). This study provides evidence that BeWo cell turnover is altered following exposure to hypoxia or ROS. It is concluded that BeWo cell culture is an appropriate model for investigating the regulation of trophoblast cell turnover. In addition, these data support a role for p53 in mediating altered trophoblast cell turnover in response to oxidative stress.

Effect of exercise on the rat mammary gland: implications for carcinogenesis

Physical activity has been associated with decreased risk for developing breast cancer yet to date, the mechanism remains unknown. The purpose of this investigation was to evaluate the effects of moderate exercise training on the normal mammary gland in an attempt to identify alterations or differences that might be associated with tumour inhibition. A total of 170 female Sprague-Dawley rats were randomized to baseline (n=10), exercise (EX; n=80), or sham-exercise groups (SHAM; n=80). Treadmill training (20-25 m min-1, 15% grade, 30 min day-1, 5 days week-1) was started at 28 days of age (DOA). Animals were killed at 28, 42, 56, 70 and 84 DOA. Mammary glands were evaluated by histology and immunohistochemistry. Terminal end buds (TEB), structures susceptible to carcinogenesis, were counted. Sexual maturation, estradiol and progesterone, and organ and muscle weights were also evaluated. No differences in growth, sexual maturation, or steroid hormones were observed in response to training. No difference in the number of TEBs was observed at any timepoint between EX and SHAM. Proliferation was significantly increased at 56 DOA and tended to be increased at 42 and 70 DOA in the EX animals whereas cell death was significantly increased at 70 DOA and tended to be increased at 84 DOA in the EX animals. These data suggest no difference in the number of carcinogen-susceptible structures as a result of moderate exercise. The changes in cell proliferation and apoptosis with exercise training suggest altered cell turnover that will necessitate future study particularly with relevance to carcinogenesis.

Protein restriction in pregnancy is associated with increased apoptosis of mesenchymal cells at the start of rat metanephrogenesis

In rats, offspring born to mothers supplied low protein diets during pregnancy have fewer glomeruli than normal. We hypothesized that such nephron deficits are associated with altered cell turnover in the metanephros, the embryonic precursor of the adult kidney. Wistar rats were supplied with one of three isocaloric diets from day 0 of pregnancy: control (18% protein) or low protein (9% or 6%) diets. All had a normal chow after birth. Groups were compared by multilevel statistical modeling. At two weeks postnatally, when nephrogenesis has finished, controls had 16.8 x 103 +/- 0.7 x 10(3) (mean +/- SEM) glomeruli/kidney, whereas offspring exposed to 9% diet had 5.1 x 10(3) +/- 1.2 x 10(3) fewer and those exposed to 6% diet had 6.9 x 10(3) +/- 1.7 x 10(3) fewer glomeruli/kidney (P < 0.001, both diets). At embryonic day 13 (E13), when the metanephros has just formed, control metanephroi contained 2.35 x 10(4) +/- 0.15 x 10(4) cells, with no significant differences in low protein groups. At E15, when mesenchyme begins forming primitive nephrons but glomeruli are still absent, controls had 2.00 x 10(6) +/- 0.13 x 10(6) cells. E15 embryos exposed to 9% protein had 1.09 x 10(6) +/- 0.36 x 10(6) fewer cells/metanephros than controls, while those exposed to 6% diet had 1.45 x 10(6) +/- 0.37 x 10(6) fewer (P < 0.01, both diets). Apoptotic cells were detected by molecular (in-situ end-labeling) and morphological (propidium iodide staining) techniques. In all diets, apoptosis was noted in condensing mesenchyme (nephron precursors) and loose mesenchyme (interstitial precursors). Control E13 metanephroi had 63 +/- 7 apoptotic cells/mm2, whereas those exposed to 9% diet had an increase of 77 +/- 26 cells/mm2 (P < 0.01) and those exposed to 6% diet had an increase of 55 +/- 26 cells/mm2 (P < 0.05). By E15, apoptosis was similar in all groups but metanephric mitosis was significantly increased in the 6% protein diet group. No change was found in the level of apoptosis in E13 mesonephroi. Maternal low protein diets reduce final numbers of glomeruli in association with enhanced deletion of mesenchymal cells at the start of kidney development. Whether aberrant nephrogenesis is a direct effect from deletion of nephron precursors, or an indirect effect from loss of supportive interstitial precursors, requires further investigation.

Altered mucin expression in the gastrointestinal tract: a review.

Early studies of changes in mucin expression in disorders of the gastrointestinal tract focused on alterations in the carbohydrate chain. This review briefly considers the various mechanisms by which such alterations may come about: (a) normal variation, (b) sialic acid alterations, (c) defective assembly of carbohydrate side-chains, (d) changed expression of core proteins and (e) epithelial metaplasia. The availability of monoclonal antibodies to mucin core proteins adds a new dimension to mucin histochemistry. It is now possible to offer explanations for traditional mucin histochemical findings on the basis of lineage-specific patterns of mucin core protein expression. Changes in core protein expression are described in inflammatory, metaplastic and neoplastic disorders of the gastrointestinal tract. The possibility that mucin change could be important in the aetiology of some diseases such as ulcerative colitis and H. pylori gastritis is considered. It is more probable, however, that changes in mucin expression are secondary to reprogramming of cellular differentiation and altered cell turnover. As such they may serve as markers to explain pathogenesis and provide novel diagnostic and prognostic information.

Bacteria in the aetio-pathogenesis of gastric cancer: a review.

Severe atrophic gastritis, a precursor lesion of gastric carcinoma, is connected, in two different ways, with intragastric bacterial colonization: (1) in advanced atrophic body gastritis (type A), achlorhydria or severe hypochlorhydria leads to bacterial overgrowth with aerobic and anaerobic flora enabling the conversion of nitrate to nitrite and further to N-nitroso compounds; (2) the newly re-discovered Helicobacter pylori is probably one of the major causes of chronic atrophic antral gastritis (type B). Both types of bacteria may be involved in the pathogenesis of multifocal gastritis (type AB). In the western world, achlorhydric atrophic gastritis is not only found in pernicious anaemia but is latent in about 2 to 6% of the general population. In one study from the Mayo Clinic, about one-third of consecutive gastric carcinomas were present in achlorhydric stomachs, the remainder in acid-secretors. Apart from the N-nitroso compounds, other carcinogenic mechanisms may be active in type A gastritis: elevated serum gastrin; altered cell turnover; immunologic and hereditary traits. The association of H. pylori with gastric carcinoma is mainly based on circumstantial evidence: (i) epidemiological studies indicate a moderately increased risk for gastric cancer in H. pylori-positive subjects compared with H. pylori-negative; (ii) in the presence of H. pylori intragastric levels of the anti-oxidant ascorbic acid are lowered; (iii) H. pylori seems to be linked to mucosal atrophy and intestinal metaplasia; (iv) recent follow-up studies show a significant development of atrophic gastritis in H. pylori-positive patients compared to H. pylori-negative.(ABSTRACT TRUNCATED AT 250 WORDS)