Decreased acylated and total ghrelin levels in bipolar disorder patients recovering from a manic episode

BACKGROUND

To date, only few studies have investigated ghrelin levels in bipolar disorders, and all have exclusively measured acylated ghrelin, with none investigating total ghrelin (acylated and des-acylated). We aimed to investigate peripheral levels of acylated and total ghrelin in subjects experiencing a manic episode of bipolar disorder.

METHODS

Peripheral levels of acylated and total ghrelin were measured in hospitalised medicated individuals recovering from a manic episode. Enzyme-linked immunosorbent assays (ELISA) were used to measure ghrelin levels in patients and compared with healthy controls. The relationship between ghrelin levels in bipolar disorder, self-reported hunger measures, demographic and clinical parameters was investigated with correlational analyses.

RESULTS

Twenty-four subjects (15 males, 9 females) recovering from mania and 27 matched healthy controls (13 males, 14 females) were recruited for the study. Mean values of both acylated (187 vs.520 pg/mL) and total ghrelin (396 vs. 648 pg/mL) were significantly reduced in bipolar disorder (p = 0.001). Ghrelin levels correlated positively with markers of illness severity and negatively with prescribed mood stabilizers, second-generation antipsychotics, weight and body mass index.

CONCLUSION

Peripheral measurements of acylated and total ghrelin were both reduced in bipolar disorder patients compared to healthy controls. Whilst illness severity promotes higher ghrelin levels, pharmacological treatment and weight gain exercise the opposite effect.

Vitamin D Is Necessary for Murine Gastric Epithelial Homeostasis

Unlike other organs, the importance of VD in a normal stomach is unknown. This study focuses on understanding the physiological role of vitamin D in gastric epithelial homeostasis. C57BL/6J mice were divided into three groups that were either fed a standard diet and kept in normal light/dark cycles (SDL), fed a standard diet but kept in the dark (SDD) or fed a vitamin D-deficient diet and kept in the dark (VDD). After 3 months, sera were collected to measure vitamin D levels by LC-MS/MS, gastric tissues were collected for immunohistochemical and gene expression analyses and gastric contents were collected to measure acid levels. The VDD group showed a significant decrease in the acid-secreting parietal cell-specific genes Atp4a and Atp4b when compared with the controls. This reduction was associated with an increased expression of an antral gastrin hormone. VDD gastric tissues also showed a high proliferation rate compared with SDL and SDD using an anti-BrdU antibody. This study indicates the requirement for normal vitamin D levels for proper parietal cell functions.

Modulation of Stem Cell Progeny by Probiotics during Regeneration of Gastric Mucosal Erosions

Patients with gastric mucosal erosions are predisposed to chronic gastritis, ulcer or even cancer. The repair of mucosal erosions involves several events including proliferation of gastric epithelial stem cells. The aim of this study was to investigate the effects of the probiotic mixture of De Simone Formulation on gastric epithelial stem cell lineages in mouse models of gastric mucosal erosions. Gastric erosions were induced by a single oral gavage of 80% ethanol containing 15 mg/mL acetylsalicylic acid (5 mL/kg) following a daily dose of probiotic mixture (5 mg/day/mouse) for 10 days. In another protocol, erosions were induced by a daily gavage of acetylsalicylic acid (400 mg/kg/day/mouse) for 5 days before or after daily administration of probiotic mixture for 5 days. Control mice received water gavage for 10 days. All mice were injected with bromodeoxyuridine two hours before sacrifice to label S-phase cells. The stomachs of all mice were processed for histological examination, lectin binding, and immunohistochemical analysis. The results reveal that mice that received probiotics before or after the induction of erosion showed a decrease in erosion index with an increase in gastric epithelial stem/progenitor cell proliferation and enhanced production of mucus, trefoil factors, and ghrelin by mucous and enteroendocrine cell lineages. These mice also showed restoration of the amount of H⁺,K⁺-ATPase and pepsinogen involved in the production of the harsh acidic environment by parietal and chief cell lineages. In conclusion, this study demonstrates the beneficial effects of probiotics against gastric mucosal erosion and highlights the involvement and modulation of proliferative stem cells and their multiple glandular epithelial cell lineages.

Effects of Diesel Exhaust Particles on Mouse Gastric Stem Cells

Stem cells have attracted many scientists because of their unique properties and therapeutic applications. However, very little is known on the environmental toxins that could affect their biological features. This study focuses on the consequences of the exposure of a cell line representative of the mouse gastric stem/progenitor (mGS) cells to diesel exhaust particles (DEPs). These immortal cells were cultured using routine protocols. The DEPs were added to the culture media at 1, 10, and 100 µg/mL for 1 to 72 h. The cells were assayed for their viability, migration, oxidative stress, and the expression of genes specific for cell proliferation, pluripotency, and death. DEPs induced a reduction in the metabolic activity of mGS cells, only at a high concentration of 100 µg/mL. However, no significant effects were detected on cell migration, oxidative stress markers (glutathione and thiobarbituric acid reactive substances), and cell death related proteins/genes. Interestingly, these findings were associated with down-regulation of Notch 2 and 3 and Bmi-1 proteins and activation of STAT3 involved in the regulation of the fate of stem cells. In conclusion, this study demonstrates that mGS cells have some resistance to oxidative stress and apoptosis when exposed to DEPs at the expense of their stemness.

Probiotics Upregulate Trefoil Factors and Downregulate Pepsinogen in the Mouse Stomach

Probiotics are used in the management of some gastrointestinal diseases. However, little is known about their effects on normal gastric epithelial biology. The aim of this study was to explore how the probiotic mixture VSL#3 affects gastric cell lineages in mice with a special focus on protective and aggressive factors. Weight-matching littermate male mice (n = 14) were divided into treated and control pairs. The treated mice received VSL#3 (5 mg/day/mouse) by gastric gavage for 10 days. Control mice received only the vehicle. Food consumption and bodyweight were monitored. All mice were injected intraperitoneally with bromodeoxyuridine (120 mg/Kg bodyweight) two hours before sacrificed to label S-phase cells. Stomach tissues were processed for lectin- and immunohistochemical examination. ImageJ software was used to quantify immunolabeled gastric epithelial cells. Real-time quantitative polymerase chain reaction was used to provide relative changes in expression of gastric cell lineages specific genes. Results revealed that treated mice acquired (i) increased production of mucus, trefoil factor (TFF) 1 and TFF2, (ii) decreased production of pepsinogen, and (iii) increased ghrelin-secreting cells. No significant changes were observed in bodyweight, food consumption, cell proliferation, or parietal cells. Therefore, VSL#3 administration amplifies specific cell types specialized in the protection of the gastric epithelium.

Genetic polymorphisms and protein expression of P53 and BRCA1 in preneoplastic and neoplastic rat mammary glands

Breast cancer is the most common type of cancer and the leading cause of cancer-related deaths among women in the United Arab Emirates and worldwide. Although many factors contribute to the high incidence of breast cancer, a considerable number of cases are related to environmental factors. In the present study, breast cancer was induced in female rats using a single dose, 80 mg/kg body wt, of the environmental carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The aim of the present study, was to characterize some of the molecular changes that occur during breast cancer development in the DMBA-treated rat model. Mammary gland tissues of control and DMBA-treated rats were processed for: i) immunohistochemical probing using anti-BRCA1 antibody to characterize and correlate the localization of this cell cycle protein during progression to cancer, ii) western blotting to analyze the alteration of p53 protein expression in preneoplastic and neoplastic lesions of the mammary glands, and iii) polymerase chain reactions using primers specific for BRCA1 and P53 genes followed by single stranded conformational polymorphism (SSCP) or restriction fragment length polymorphism (RFLP) assays to detect possible mutations in these genes during development of breast cancer. Microscopic examination revealed a wide range of preneoplastic and neoplastic lesions providing a sequence representing the multistep process of breast cancer formation in DMBA-treated rats. Probing for BRCA1 protein revealed a gradual defect in its translocation from the cytoplasm to the nucleus during breast cancer progression. In control rats, BRCA1 was present in the nuclei of terminal duct epithelial cells. However, in the preneoplastic lesions, BRCA1 was localized in both the cytoplasm and nuclei of the epithelial duct cells. In all malignant lesions, BRCA1 was mostly found in the cytoplasm. Western blotting revealed initial downregulation in the expression of p53 protein during breast cancer development. However, with progression towards malignancy, upregulation of p53 was observed. These changes were associated with polymorphism in p53 gene, which was detected in exon 5 using SSCP assay. However, using RFLP and BamHI to digest the PCR products of exon 11 of BRCA1 gene revealed no detectable polymorphisms. In conclusion, molecular characterization of the early changes that occur during development of breast cancer provides some clues for better understanding of its pathogenesis.

Growth and Differentiation of Dental Stem Cells of Apical Papilla on Polycaprolactone Scaffolds

Biodegradable scaffolds are useful tools in the field of tissue engineering and regenerative medicine. The aim of this study was to test the potential of the human stem cells of apical papilla (SCAP) to attach, proliferate and differentiate on a polycaprolactone (PCL)-based scaffolds. SCAP were extracted from the root apical papillae of freshly extracted immature premolar teeth by using enzymatic digestion. Porous PCL scaffolds were fabricated using particle leaching method and NaCl or mannitol as porogens. SCAP of passage 3 were seeded on non-porous and porous PCL scaffolds for up to 14 days. For control, cells were cultured on glass coverslips. Picogreen DNA quantification was used to assay for cell proliferation. Cell differentiation and development of calcification nodules were examined using scanning electron microscopy and alizarin red staining. SCAP showed a comparable attachment, growth and proliferation patterns on PCL scaffolds and coverslips. Cell proliferation was enhanced on mannitol scaffolds at all time points. Calcification nodules were detected in all PCL scaffolds while it was not present on glass coverslips. These nodules were detected on NaCl-scaffolds by day 7 and on mannitol and non-porous scaffolds by day 14. In conclusion, SCAP were able to attach, proliferate and differentiate on PCL scaffolds without using any inductive media, indicating their potential application for dental tissue regeneration.

SMARCAD1 in Breast Cancer Progression

BACKGROUND/AIMS

Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-negative breast cancers have the worst prognosis. The identification of new genes associated with triple-negative breast cancer progression is crucial for developing more specific anti-cancer targeted therapies, which could lead to a better management of these patients. In this context, we have recently demonstrated that SMARCAD1, a DEAD/H box-containing helicase, is involved in breast cancer cell migration, invasion, and metastasis. The aim of this study was to investigate the impact of the stable knockdown of SMARCAD1 on human breast cancer cell progression.

METHODS

Using two different designs of shRNA targeting SMARCAD1, we investigated the impact of the stable knockdown of SMARCAD1 on human breast cancer cell proliferation and colony growth in vitro and on tumour growth in chick embryo and nude mouse xenograft models in vivo using MDA-MB-231 (ER-/PR-/ HER2-) and T47D (ER+/PR+/-/HER2-) human breast cancer cell lines.

RESULTS

We found that SMARCAD1 knockdown resulted in a significant decrease in breast cancer cell proliferation and colony formation, leading to the significant inhibition of tumour growth in both the chick embryo and nude mouse xenograft models. This inhibition was due, at least in part, to a decrease in IKKβ expression.

CONCLUSION

These results indicate that SMARCAD1 is involved in breast cancer progression and can be a promising target for breast cancer therapy.

Development of a therapeutic model of precancerous liver using crocin-coated magnetite nanoparticles

Despite considerable advances in understanding hepatocellular carcinoma, it is one of the common and deadliest cancers worldwide. Hence, increasing efforts are needed for early diagnosis and effective treatments. Saffron has been recently found to inhibit growth of liver cancer in rats. The aim of this study was to develop an effective method for treatment of liver cancer using magnetite nanoparticles (MNPs) coated with crocin, the main active component of saffron. MNPs were prepared and initially coated with dextran and a cross-linker to enhance conjugation of crocin using a modified coprecipitation method. Cultured HepG2 cells and diethylnitrosamine-injected mice were treated with corcin-coated MNPs and analyzed using cell proliferation assay and immunohistochemical analysis, respectively. Treatment of HepG2 cells with crocin-coated MNPs led to a significant inhibition of their growth as compared to control or those treated with free crocin or uncoated MNPs. Histological examinations of the livers of diethylnitrosamine-injected mice revealed several precancerous changes: multiple proliferative hepatic foci, hyper- or dysplastic transformations of bile ducts/ductules, and nuclear atypia associated with polyploidy, karyomegaly, and vacuolation. Immunohistochemistry using antibodies specific for cell proliferation (Ki-67) and apoptosis (M30-CytoDEATH and Bcl-2) revealed their upregulation during development of precancerous lesions. Using antibodies specific for inflammation (cyclooxygenase-2), oxidative stress (glutathione) and angiogenesis (vascular endothelial growth factor) indicated the involvement of multiple signaling pathways in the development of precancerous lesions. Treatment with crocin-coated MNPs was associated with regression of precancerous lesions, significant upregulation of apoptotic cells and downregulation of Bcl-2 labeling and markers of cell proliferation, inflammation, oxidative stress and angiogenesis. In conclusion, crocin-coated MNPs are more effective than free corcin for treatment of liver precancerous lesions in mice. These findings will help to develop new modalities for early detection and treatment of liver precancerous lesions.

3D culture of mouse gastric stem cells using porous microcarriers

The lining epithelium of the stomach includes multipotent stem cells which undergo proliferation and migration-associated differentiation. These cells give rise to multiple cell lineages that produce mucus, acid, pepsinogen and various hormones/peptides. A 3D culture for stem cells would facilitate identification of the factors that control proliferation and/or differentiation programs. Here, we report on the use of disk-like ImmobaSil HD silicone-rubber matrix based microcarriers that are permeable to oxygen and reduce the creation of toxic environment within the center of the microcarrierd for culturing the mouse gastric stem (mGS) cells. We define several parameters that affect the initial cell attachment such as size of cell inoculum, serum concentration, mode and speed of agitation. We show that although such a microcarrier allows for attachment and growth of gastric stem cells, it does not lend itself and does not support the functional differentiation of such cells.

Potential role of probiotics in the management of gastric ulcer

Gastric ulcer is one of the most common chronic gastrointestinal diseases characterized by a significant defect in the mucosal barrier. Helicobacter pylori (H. pylori) infection and the frequent long-term use of non-steroidal anti-inflammatory drugs are major factors involved in gastric ulcer development. Acid inhibitors and antibiotics are commonly used to treat gastric ulcer. However, in the last few decades, the accumulating evidence for resistance to antibiotics and the side effects of antibiotics and acid inhibitors have drawn attention to the possible use of probiotics in the prevention and treatment of gastric ulcer. Probiotics are live microorganisms that when administered in adequate amounts confer health benefits on the host. Currently, the available experimental and clinical studies indicate that probiotics are promising for future applications in the management of gastric ulcers. This review aims to provide an overview of the general health benefits of probiotics on various systemic and gastrointestinal disorders with a special focus on gastric ulcer and the involved cellular and molecular mechanisms: i) Protection of gastric mucosal barrier; ii) upregulation of prostaglandins, mucus, growth factors and anti-inflammatory cytokines; iii) increased cell proliferation to apoptosis ratio; and iv) induction of angiogenesis. Finally, some of the available data on the possible use of probiotics in H. pylori eradication are discussed.

NOTCH3 is expressed in human apical papilla and in subpopulations of stem cells isolated from the tissue

NOTCH plays a role in regulating stem cell function and fate decision. It is involved in tooth development and injury repair. Information regarding NOTCH expression in human dental root apical papilla (AP) and its residing stem cells (SCAP) is limited. Here we investigated the expression of NOTCH3, its ligand JAG1, and mesenchymal stem cell markers CD146 and STRO-1 in the AP or in the primary cultures of SCAP isolated from AP. Our in situ immunostaining showed that in the AP NOTCH3 and CD146 were co-expressed and associated with blood vessels having NOTCH3 located more peripherally. In cultured SCAP, NOTCH3 and JAG1 were co-expressed. Flow cytometry analysis showed that 7%, 16% and 98% of the isolated SCAP were positive for NOTCH3, STRO-1 and CD146, respectively with a rare 1.5% subpopulation of SCAP co-expressing all three markers. The expression level of NOTCH3 reduced when SCAP underwent osteogenic differentiation. Our findings are the first step towards defining the regulatory role of NOTCH3 in SCAP fate decision.

Profiling cellular bioenergetics, glutathione levels, and caspase activities in stomach biopsies of patients with upper gastrointestinal symptoms

AIM: To measure biochemical parameters in stomach biopsies and test their suitability as diagnostic biomarkers for gastritis and precancerous lesions.

METHODS: Biopsies were obtained from the stomachs of two groups of patients (n = 40) undergoing fiber-optic endoscopy due to upper gastrointestinal symptoms. In the first group (n = 17), only the corpus region was examined. Biopsies were processed for microscopic examination and measurement of mitochondrial O₂ consumption (cellular respiration), cellular adenosine triphosphate (ATP), glutathione (GSH), and caspase activity. In the second group of patients (n = 23), both corpus and antral regions were studied. Some biopsies were processed for microscopic examination, while the others were used for measurements of cellular respiration and GSH level.

RESULTS: Microscopic examinations of gastric corpus biopsies from 17 patients revealed normal mucosae in 8 patients, superficial gastritis in 7 patients, and chronic atrophic gastritis in 1 patient. In patients with normal histology, the rate (mean ± SD) of cellular respiration was 0.17 ± 0.02 μmol/L O₂ min^-1 mg^-1, ATP content was 487 ± 493 pmol/mg, and GSH was 469 ± 98 pmol/mg. Caspase activity was detected in 3 out of 8 specimens. The values of ATP and caspase activity were highly variable. The presence of superficial gastritis had insignificant effects on the measured biomarkers. In the patient with atrophic gastritis, cellular respiration was high and ATP was relatively low, suggesting uncoupling oxidative phosphorylation. In the second cohort of patients, the examined biopsies showed either normal or superficial gastritis. The rate of cellular respiration (O_2.μmol/L min^-1 mg^-1) was slightly higher in the corpus than the antrum (0.18 ± 0.05 vs 0.15 ± 0.04, P = 0.019). The value of GSH was about the same in both tissues (310 ± 135 vs 322 ± 155, P = 0.692).

CONCLUSION: The corpus mucosa was metabolically more active than the antrum tissue. The data in this study will help in understanding the pathophysiology of gastric mucosa.

Establishment of a three-dimensional culture system of gastric stem cells supporting mucous cell differentiation using microfibrous polycaprolactone scaffolds

OBJECTIVES

To generate various polycaprolactone (PCL) scaffolds and test their suitability for growth and differentiation of immortalized mouse gastric stem (mGS) cells.

MATERIALS AND METHODS

Non-porous, microporous and three-dimensional electrospun microfibrous PCL scaffolds were prepared and characterized for culture of mGS cells. First, growth of mGS cells was compared on these different scaffolds after 3 days culture, using viability assay and microscopy. Secondly, growth pattern of the cells on microfibrous scaffolds was studied after 3, 6, 9 and 12 days culture using DNA PicoGreen assay and scanning electron microscopy. Thirdly, differentiation of the cells grown on microfibrous scaffolds for 3 and 9 days was analysed using lectin/immunohistochemistry.

RESULTS

The mGS cells grew preferentially on microfibrous scaffolds. From 3 to 6 days, there was increase in cell number, followed by reduction by days 9 and 12. To test whether the reduction in cell number was associated with cell differentiation, cryosections of cell-containing scaffolds cultured for 3 and 9 days were probed with gastric epithelial cell differentiation markers. On day 3, none of the markers examined bound to the cells. However by day 9, approximately, 50% of them bound to N-acetyl-d-glucosamine-specific lectin and anti-trefoil factor 2 antibodies, indicating their differentiation into glandular mucus-secreting cells.

CONCLUSIONS

Microfibrous PCL scaffolds supported growth and differentiation of mGS cells into mucus-secreting cells. These data will help lay groundwork for future experiments to explore use of gastric stem cells and PCL scaffolds in stomach tissue engineering.

Short-term effects of oral administration of Pistacia lentiscus oil on tissue-specific toxicity and drug metabolizing enzymes in mice

BACKGROUND

Pistacia lentiscus (Anacardiaceae) is a flowering plant traditionally used in the treatment of various skin, respiratory, and gastrointestinal disorders. The aim of this study was to assess whether Pistacia lentiscus oil has any short term toxic effects in vivo and in vitro.

METHODS

Pistacia lentiscus oil (100µl) was administered orally into mice for 5 days.

RESULTS

Measurements of body weight did not show any weight loss. Serum concentration of LDH did not show any significant statistical difference when compared to control mice. Similarly, blood, kidney or liver function tests showed no toxicity with Pistacia lentiscus oil when compared to the control group. Examination of gastrointestinal tissues sections revealed similar structural features with no difference in cell proliferation. In this context, pharmacological dilutions of Pistacia lentiscus oil (10(-6) - 10(-3)) did not affect the viability (cell death and proliferation) of mouse gastric stem cells, human colorectal cancer cells HT29, human hepatoma cells HepG2. However, it appears that at the dose and time point studied, Pistacia lentiscus oil treatment has targeted various cytochrome P450s and has specifically inhibited the activities and the expression of CYP2E1, CYP3A4, CYP1A1 and CYP1A2 differentially in different tissues. Our results also demonstrate that there is no appreciable effect of Pistacia lentiscus oil on the GSH-dependent redox homoeostasis and detoxification mechanism in the tissues.

CONCLUSION

These data suggest a good safety profile of short term oral use of Pistacia lentiscus oil as a monotherapy in the treatment of various skin, respiratory, and gastrointestinal disorders. However, due to its inhibitory effect of various cytochrome P450s and mainly CYP3A4, this might have implications on the bioavailability and metabolism of drugs taken in combination with Pistacia lentiscus oil. More attention is needed when Pistacia lentiscus oil is intended to be uses in combination with other pharmacological agents in order to avoid potential drug-drug interaction leading to toxicity. This study will help in safer use of Pistacia lentiscus oil for therapeutic purpose.

Ghrelin knockout mice show decreased voluntary alcohol consumption and reduced ethanol-induced conditioned place preference

Recent work suggests that stomach-derived hormone ghrelin receptor (GHS-R1A) antagonism may reduce motivational aspects of ethanol intake. In the current study we hypothesized that the endogenous GHS-R1A agonist ghrelin modulates alcohol reward mechanisms. For this purpose ethanol-induced conditioned place preference (CPP), ethanol-induced locomotor stimulation and voluntary ethanol consumption in a two-bottle choice drinking paradigm were examined under conditions where ghrelin and its receptor were blocked, either using ghrelin knockout (KO) mice or the specific ghrelin receptor (GHS-R1A) antagonist "JMV2959". We showed that ghrelin KO mice displayed lower ethanol-induced CPP than their wild-type (WT) littermates. Consistently, when injected during CPP-acquisition, JMV2959 reduced CPP-expression in C57BL/6 mice. In addition, ethanol-induced locomotor stimulation was lower in ghrelin KO mice. Moreover, GHS-R1A blockade, using JMV2959, reduced alcohol-stimulated locomotion only in WT but not in ghrelin KO mice. When alcohol consumption and preference were assessed using the two-bottle choice test, both genetic deletion of ghrelin and pharmacological antagonism of the GHS-R1A (JMV2959) reduced voluntary alcohol consumption and preference. Finally, JMV2959-induced reduction of alcohol intake was only observed in WT but not in ghrelin KO mice. Taken together, these results suggest that ghrelin neurotransmission is necessary for the stimulatory effect of ethanol to occur, whereas lack of ghrelin leads to changes that reduce the voluntary intake as well as conditioned reward by ethanol. Our findings reveal a major, novel role for ghrelin in mediating ethanol behavior, and add to growing evidence that ghrelin is a key mediator of the effects of multiple abused drugs.

Upregulation and inhibition of the nuclear translocation of Oct4 during multistep gastric carcinogenesis

Gastric cancer is the fourth most commonly diagnosed malignancy and the second leading cause of cancer-related mortality worldwide. Recent research suggests that tissue stem cells and the self renewal transcription factor, octamer-binding transcription factor 4 (Oct4), could be involved in the development of certain tumors. The aim of this study was to investigate the expression pattern of Oct4 in normal human stomach and during multistep gastric carcinogenesis. Pyloric antral mucosal tissues were obtained from consenting individuals undergoing endoscopy (due to upper gastrointestinal symptoms) and gastrectomy (due to pyloric antral adenocarcinoma). Some tissue samples were processed to assemble an array of tissue sections representing multistep carcinogenesis and probed using anti-Oct4 antibodies and lectins specific for α-L-fucose or N-acetyl-D-glucosamine. Some tissue samples were processed for subcellular fractionation and western blot analysis using the same antibodies. The results revealed that Oct4-expressing cells were found in the proliferative cell compartment of the pit-gland units of microscopically normal gastric mucosal biopsies. Mucosal tissues with evidence of severe gastritis, metaplastic/dysplastic transformation and gastric cancer showed a significant increase in the expression of Oct4 (the labeled area increased from 2% in the control to 6 and 16% in the gastritis and cancerous tissues, respectively), suggesting a role for Oct4 in the early stages of cancer development. Furthermore, the data revealed an alteration in the subcellular distribution of Oct4, possibly due to the inhibition of cytoplasm-to-nucleus translocation during carcinogenesis. In conclusion, this study demonstrates an alteration in the expression pattern and nuclear translocation of Oct4 during gastric carcinogenesis and may be helpful in designing new modalities for the early detection and/or therapy of gastric cancer.

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

In a few recent studies, the presence of arrhythmias based on reentry and circus movement of the slow wave have been shown to occur in normal and diseased stomachs. To date, however, reentry has not been demonstrated before in any other part of the gastrointestinal system. No animals had to be killed for this study. Use was made of materials obtained during the course of another study in which 11 rats were treated with streptozotocin and housed with age-matched controls. After 3 and 7 mo, segments of duodenum, jejunum, and ileum were isolated and positioned in a tissue bath. Slow wave propagation was recorded with 121 extracellular electrodes. After the experiment, the propagation of the slow waves was reconstructed. In 10 of a total of 66 intestinal segments (15%), a circus movement of the slow wave was detected. These reentries were seen in control (n = 2) as well as in 3-mo (n = 2) and 7-mo (n = 6) diabetic rats. Local conduction velocities and beat-to-beat intervals during the reentries were measured (0.42 ± 0.15 and 3.03 ± 0.67 cm/s, respectively) leading to a wavelength of 1.3 ± 0.5 cm and a circuit diameter of 4.1 ± 1.5 mm. This is the first demonstration of a reentrant arrhythmia in the small intestine of control and diabetic rats. Calculations of the size of the circuits indicate that they are small enough to fit inside the intestinal wall. Extrapolation based on measured velocities and rates indicate that reentrant arrhythmias are also possible in the distal small intestine of larger animals including humans.

Slow wave propagation and plasticity of interstitial cells of Cajal in the small intestine of diabetic rats

The number of myenteric interstitial cells of Cajal (ICC-MY), responsible for the generation and propagation of the slow wave in the small intestine, has been shown to decrease in diabetes, suggesting impairment of slow-wave (SW) propagation and related motility. To date, however, this expected decrease in SW propagation has neither been recorded nor analysed. Eleven rats were treated with streptozotocin and housed in pairs with 11 age-matched control animals. After 3 or 7 months, segments of duodenum, jejunum and ileum were isolated and divided into two parts. One part was processed for immediate freezing, cryosectioning and immunoprobing using anti-c-Kit antibody to quantify ICC-MY. The second part was superfused in a tissue bath, and SW propagation was recorded with 121 extracellular electrodes. In addition, a cellular automaton was developed to study the effects of increasing the number of inactive cells on overall propagation. The number of ICC-MY was significantly reduced after 3 months of diabetes, but rebounded to control levels after 7 months of diabetes. Slow-wave frequencies, velocities and extracellular amplitudes were unchanged at any stage of diabetes. The cellular automaton showed that SW velocity was not linearly related to the number of inactive cells. The depletion of ICC-MY is not as severe as is often assumed and in fact may rebound after some time. In addition, at least in the streptozotocin model, the initial reduction in ICC-MY is not enough to affect SW propagation. Diabetic intestinal dysfunction may therefore be more affected by impairments of other systems, such as the enteric system or the muscle cells.

Ghrelin attenuates gastrointestinal epithelial damage induced by doxorubicin

AIM: To examine the influence of ghrelin on the regenerative potential of gastrointestinal (GI) epithelium.

METHODS: Damage to GI epithelium was induced in mice by two intravenous injections of doxorubicin (10 and 6 mg/kg). Some of the doxorubicin-treated mice received a continuous subcutaneous infusion of ghrelin (1.25 μg/h) for 10 d via implanted mini-osmotic pumps. To label dividing stem cells in the S-phase of the cell cycle, all mice received a single intraperitoneal injection of 5’-bromo-2’-deoxyuridine (BrdU) one hour before sacrifice. The stomach along with the duodenum were then removed and processed for histological examination and immunohistochemistry using anti-BrdU antibody.

RESULTS: The results showed dramatic damage to the GI epithelium 3 d after administration of chemotherapy which began to recover by day 10. In ghrelin-treated mice, attenuation of GI mucosal damage was evident in the tissues examined post-chemotherapy. Immunohistochemical analysis showed an increase in the number of BrdU-labeled cells and an alteration in their distribution along the epithelial lining in response to damage by doxorubicin. In mice treated with both doxorubicin and ghrelin, the number of BrdU-labeled cells was reduced when compared with mice treated with doxorubicin alone.

CONCLUSION: The present study suggests that ghrelin enhances the regenerative potential of the GI epithelium in doxorubicin-treated mice, at least in part, by modulating cell proliferation.

Sequential alterations in gastric biopsies and tumor tissues support the multistep process of carcinogenesis

Gastric cancer is the second leading cause of cancer related death worldwide. In the UAE, recent data show an increase in the number of patients with gastric cancer highlighting the need for greater understanding of its pathogenesis. Gastric cancer is generally believed to develop on a background of chronic atrophic gastritis which eventually leads to intestinal metaplasia, dysplasia and finally invasive carcinoma. Recently this multistep process of carcinogenesis has been challenged. Therefore, the aim of this study is to define alterations in antral mucosal biopsies and cancer tissues to investigate whether they could be used to assemble a tissue array supporting the multistep model of carcinogenesis. Gastric mucosal tissues were obtained from informed individuals undergoing endoscopy (for upper gastrointestinal symptoms) and gastrectomy (for adenocarcinoma) in Tawam Hospital. All tissues were processed for microscopic examination. Eighty nine antral biopsies were categorized as: normal (33%), mild superficial gastritis (34%) and severe atrophic gastritis (33%). About 5% of the latter exhibited evidence of intestinal metaplasia. Cancer tissues obtained from three patients were microscopically examined in three regions: safe resected margin, tumor edge and tumor center. Progressive changes in mucosal thickness, dysplasia and cellular transformation were observed, and when compared with alterations in biopsies, all appeared to represent a continuum of progression toward invasive adenocarcinoma. In conclusion, the tissue array presented in this study supports the multistep process of gastric carcinogenesis and will be helpful in examining the expression pattern of tumor markers or molecules that could help in the early detection of gastric cancer.

A focus on parietal cells as a renewing cell population

The fact that the acid-secreting parietal cells undergo continuous renewal has been ignored by many gastroenterologists and cell biologists. In the past, it was thought that these cells were static. However, by using (3)H-thymidine radioautography in combination with electron microscopy, it was possible to demonstrate that parietal cells belong to a continuously renewing epithelial cell lineage. In the gastric glands, stem cells anchored in the isthmus region are responsible for the production of parietal cells. The stem cells give rise to three main progenitors: prepit, preneck and preparietal cells. Parietal cells develop either directly from the non-cycling preparietal cells or less commonly via differentiation of the cycling prepit and preneck cell progenitors. The formation of a parietal cell is a sequential process which involves diminishment of glycocalyx, production of cytoplasmic tubulovesicles, an increase in number and length of microvilli, an increase in number and size of mitochondria, and finally, expansion and invagination of the apical membrane with the formation of an intracellular canalicular system. Little is known about the genetic counterparts of these morphological events. However, the time dimension of parietal cell production and the consequences of its alteration on the biological features of the gastric gland are well documented. The production of a new parietal cell takes about 2 d. However, mature parietal cells have a long lifespan during which they migrate bi-directionally while their functional activity for acid secretion gradually diminishes. Following an average lifespan of about 54 d, in mice, old parietal cells undergo degeneration and elimination. Various approaches for genetic alteration of the development of parietal cells have provided evidence in support of their role as governors of the stem/progenitor cell proliferation and differentiation programs. Revealing the dynamic features and the various roles of parietal cells would help in a better understanding of the biological features of the gastric glands and would hopefully help in providing a basis for the development of new strategies for prevention, early detection and/or therapy of various gastric disorders in which parietal cells are involved, such as atrophic gastritis, peptic ulcer disease and gastric cancer.

Mouse models demonstrating the role of stem/progenitor cells in gastric carcinogenesis

Advances have been made in identifying the gastric epithelial stem cells and their immediate descendents which act as uncommitted or committed progenitors giving rise to cell lineages producing the various contents of the gastric juice and several hormones. New research suggests that these epithelial stem/progenitor cells also play an important role in the development of gastric cancer. In this review, we summarize results of examining three genetically manipulated mouse models in which the biological features and differentiation program of the gastric stem/progenitor cells were altered by three different approaches: 1) knockout of the trefoil factor 1 gene which is expressed initially in the partially committed pre-pit cell progenitors known to produce both mucus- and acid-secreting cell lineages, 2) expression of Simian virus 40 large T antigen gene in the acid-secreting parietal cell lineage, and 3) ablation of the parietal cells by using the attenuated diphtheria toxin A fragment. Systematic analysis of these animal models provided some clues to the role played by gastric stem/progenitor cells during carcinogenesis and to the cellular origin of gastric cancer.

Dysregulation of gastric H,K-ATPase by cigarette smoke extract

AIM

To test whether the expression and activity of H,K-ATPase in parietal cells would be affected by cigarette smoke extract.

METHODS

Extracts of cigarette smoke were administered into mice by gastric gavage (5 mg/kg body weight/day) for 3 d or in drinking water for 7 or 14 d. For the latter, each day a mouse consumed 5 mL water containing extracts of two cigarettes, on average. Control littermate mice received only vehicle. To compare the amount of H,K-ATPase in control and smoke-treated mice, the stomach was processed for Western blotting and immunohistochemical analysis using monoclonal antibodies specific for alpha- or beta-subunits of H,K-ATPase. The p-nitrophenylphosphatase activity assay was used as a measurement for K-dependent H,K-ATPase activity.

RESULTS

Probed transblots showed an increase in the amount of H,K-ATPase in smoke-treated mice which was confirmed by immunohistochemistry and was found to be due to increased amounts of protein per parietal cell rather than an increased parietal cell number. The increase in the amount of H,K-ATPase was associated with an enhancement of its enzymatic activity. K-dependent activity in control and smoke-treated mice was significantly different (respectively, 0.12 micromol/mg vs 0.27 micromol/mg per minute, P < 0.05).

CONCLUSION

Administration of cigarette smoke extract is associated with an increase in the amount and activity of H,K-ATPase and hence, smokers are susceptible to development of peptic ulcer.

Amplification and invasiveness of epithelial progenitors during gastric carcinogenesis in trefoil factor 1 knockout mice

OBJECTIVE

It is not known whether or not epithelial progenitors of the pyloric antrum are involved in gastric carcinogenesis. Normally, these progenitors give rise to two main cell lineages: pit and gland mucous cells. This study was designed to examine the changes that occur in pyloric antral mucous cell lineages and their progenitors during development of gastric adenoma and carcinoma in trefoil factor 1 (TFF1) knockout mice.

MATERIALS AND METHODS

Pyloric antral mucosal tissues of TFF1 knockout mice at ages from 3 days to 17 months were processed for histochemical analysis using Ulex europaeus and Grifforia simplifolica lectins as markers for pit and gland mucous cells, respectively. The dividing epithelial progenitors were identified by using immunohistochemical and electron microscopy techniques.

RESULTS

TFF1 loss was associated with amplification of both mucus-secreting pit and gland cells. Both lectins examined bound not only to mature mucous cells, but also to most of epithelial progenitors which gradually amplified with age and frequently were seen in mitosis. Analysis of 12- to 17-month-old TFF1-deficient stomachs revealed occasional groups of poorly differentiated mucosal cells with features similar to those of epithelial progenitors (or stem cells), in the basal portion of the antral mucosa. These cells eventually invaded the muscularis mucosa while maintaining some capacity to differentiate.

CONCLUSION

This study shows that the progenitors of pit and gland mucous cells contribute to gastric carcinogenesis in the pyloric antrum of TFF1 knockout mice, strongly supporting the concept of stem cell origin of cancer.

Cellular origin of gastric cancer

Gastric cancer is the second leading cause of cancer deaths worldwide. Although the link between Helicobacter pylori infection and gastric cancer is well established, little is known about the early development and detection of this malignant disease. Cancer is the disease of epithelia and recently, it has been suggested that some cancers originate in adult stem cells. Advances have been made in identifying the gastric epithelial stem cells and their immediate descendents, which act as progenitors giving rise to mucus-, acid-, pepsinogen-, and hormone-secreting cell lineages. Analyses of some genetically manipulated animal models in which the proliferation and differentiation program of the gastric stem/progenitor cells was altered by different approaches have provided some clues to the cellular origin of gastric cancer. Despite the challenges and the similarity between gastric epithelial progenitors and their differentiation program in mice and humans, it remains to be determined whether observations made in genetically engineered mice are also applicable to humans.

Characterization of breast cancer progression in the rat

The incidence of breast cancer is continuously increasing worldwide. This increasing trend is attributed partly to the fact that a considerable number of cases are related to environmental factors and partly to the little information available on the early changes that occur during mammary gland carcinogenesis. To characterize some of these early cellular changes, breast cancer was induced in female rats using a single intragastric dose of the environmental carcinogen 7,12-dimethylbenz[a]anthracene (DMBA; 80 mg/kg body weight). Mammary gland tissues of control and DMBA-treated rats were processed for routine histopathological examination and immunohistochemical analysis using an antibody specific for the proliferating cell nuclear antigen (PCNA). Microscopic examination of all mammary glands of DMBA-treated rats revealed a wide range of preneoplastic stages in addition to the well-characterized benign and malignant tumors that developed. The first stage was characterized by slightly dilated terminal ducts with accumulation of dead cells. This was designated the stage of cell death. Then, stages of hyperplasia, dysplasia, and carcinoma in situ followed. Immunohistochemical localization of PCNA in these preneoplastic lesions revealed an initial decrease followed by a gradual increase in the labeling index of PCNA. In conclusion, the DMBA-treated rats provide a useful model to dissect the early changes that occur during the multistep process of mammary gland carcinogenesis.

Establishment of a gastric epithelial progenitor cell line from a transgenic mouse expressing the simian virus 40 large T antigen gene in the parietal cell lineage

OBJECTIVE

In this study the gastric mucosa of transgenic mice expressing the simian virus 40 large T antigen gene in the parietal cell lineage is used to establish and characterize a new epithelial progenitor cell line. In these mice, proliferation and amplification of preparietal cells preclude their maturation into acid-secreting parietal cells leading to achlorohydria, hyperplasia, dysplasia and eventually gastric adenocarcinoma.

MATERIALS AND METHODS

Enzymatically dispersed gastric epithelial cells were cultured, cloned and screened using immunohistochemical methods, for expression of a variety of biomarkers of differentiated pit, parietal, enteroendocrine and neck/zymogenic cells.

RESULTS

A biomarker-deficient cell line whose ultrastructural features resembled those of mouse gastric epithelial progenitor cells was established. Treatment with either hydrocortisone or oestrogen significantly enhanced proliferation of these cells, whereas retinoic acid inhibited their growth. No change in differentiation was detected with any of these treatments; however, when these cells were injected subcutaneously into nude mice, they proliferated to form tumours and undergo partial differentiation towards parietal cell lineage.

CONCLUSION

This mouse gastric epithelial progenitor cell line could be useful as an in vitro model to study growth properties, proliferation and differentiation of a subpopulation of gastric epithelial progenitor cells and also to study gastric carcinogenesis.

Helicobacter pylori evolution during progression from chronic atrophic gastritis to gastric cancer and its impact on gastric stem cells

We have characterized the adaptations of Helicobacter pylori to a rarely captured event in the evolution of its impact on host biology-the transition from chronic atrophic gastritis (ChAG) to gastric adenocarcinoma-and defined the impact of these adaptations on an intriguing but poorly characterized interaction between this bacterium and gastric epithelial stem cells. Bacterial isolates were obtained from a single human host colonized with a single dominant strain before and after his progression from ChAG to gastric adenocarcinoma during a 4-year interval. Draft genome assemblies were generated from two isolates, one ChAG-associated, the other cancer-associated. The cancer-associated strain was less fit in a gnotobiotic transgenic mouse model of human ChAG and better able to establish itself within a mouse gastric epithelial progenitor-derived cell line (mGEP) that supports bacterial attachment. GeneChip-based comparisons of the transcriptomes of mGEPs and a control mouse gastric epithelial cell line revealed that, upon infection, the cancer-associated strain regulates expression of GEP-associated signaling and metabolic pathways, and tumor suppressor genes associated with development of gastric cancer in humans, in a manner distinct from the ChAG-associated isolate. The effects on GEP metabolic pathways, some of which were confirmed in gnotobiotic mice, together with observed changes in the bacterial transcriptome are predicted to support aspects of an endosymbiosis between this microbe and gastric stem cells. These results provide insights about how H. pylori may adapt to and influence stem cell biology and how its intracellular residency could contribute to gastric tumorigenesis.

Expression of TFF3 during multistep colon carcinogenesis

The pathogenesis of colon cancer is not well understood. This common type of cancer is generally believed to occur in a multistep process which involves alterations of various tumor suppressor genes and oncogenes during the progression through benign lesions towards carcinoma. TFF3 is a product of the colonic epithelium and has been implicated in colonic mucosal protection and also in the aggressiveness of colon cancer cells. The aim of this study was to analyze the expression of TFF3 during propagation towards cancer development in the human colon. Colonic tissues representing colitis, adenomatous polyposis, tubulovillous adenoma, and mucoid/adeno-carcinomas were processed for immunohistochemistry using an antibody specific for human TFF3. The results were correlated with those of PCNA-labeling, quantified, and compared with those of control tissues obtained from the safe margin of macroscopically normal colonic mucosa of patients with colon cancer. The data showed marked down-regulation of TFF3 expression in adenomatous polyposis, then TFF3 expression returns to about control level during adenoma and remains high during mucoid- and adeno-carcinomas. Colonic tissues with highly invasive cancer cells were characterized by statistically significant down-regulation of TFF3 expression. The changes observed in expression of TFF3 showed an inverse correlation with cell proliferation and suggest that it might play a protective role against colon carcinogenesis.

Expression of retinoid receptors in multiple cell lineages in the gastric mucosae of mice and humans

BACKGROUND AND AIM

In mice and humans, the gastric epithelial progenitors undergo proliferation and bipolar migration from the isthmus associated with their differentiation into mucus-, acid- and pepsinogen-secreting cell lineages. Little is known about factors that control the dynamics of these isthmal progenitor cells. Retinoids have long been known as chemopreventive agents against gastric mucosal damage and carcinogenesis. The aim of the present study was to examine the cellular localization of the various retinoid receptors proteins (RAR and RXR) in the gastric epithelium of mice and humans.

METHODS

Gastric antral biopsies of normal individuals and the oxyntic and antral regions of the mouse stomach were processed for immunohistochemistry using anti-RAR and anti-RXR antibodies. To label the progenitor cell zone, some sections were also probed with antibodies specific for proliferating cell nuclear antigen.

RESULTS

The immunoprobed oxyntic mucosal sections of the mice showed that RXRbeta protein was present in the epithelial isthmal cells, neck cells, zymogenic cells and some pit and parietal cells. In addition, RARbeta was found in isthmal and neck cells, and RARgamma was mainly found in neck cells. In the mouse antrum, only RXRbeta was detected in the isthmal cells and their pit and gland cell descendents. In humans, immunoprobed antral sections showed that RARbeta, RARgamma, RXRalpha and RXRgamma proteins are expressed in the isthmal, pit and gland cells.

CONCLUSIONS

Retinoid receptors are expressed in multiple cell lineages of the mouse and human gastric epithelium and may, therefore, account for the possible effects of retinoids on gastric epithelial cell proliferation and differentiation.

Intracellular Helicobacter pylori in gastric epithelial progenitors

Helicobacter pylori is generally viewed as an extracellular pathogen. We have analyzed the tropism of H. pylori clinical isolates in a gnotobiotic transgenic mouse model of human chronic atrophic gastritis, a preneoplastic condition. These mice lack acid-producing parietal cells and have an amplified population of dividing gastric epithelial progenitors (GEPs) that express NeuAc alpha 2,3Gal beta 1,4-glycans recognized by H. pylori adhesins. Scanning confocal and transmission electron microscopic studies of stomachs that had been colonized for 1 month or 1 year revealed intracellular bacterial collections (IBCs) in a small subset of multi- and oligopotential epithelial progenitors. Transmission electron microscopic and multilabel immunohistochemical analyses disclosed bacteria with several morphotypes, including spiral-shaped, in the cytoplasm and endosomes. Several stages in IBC evolution were documented, from a few solitary bacteria to consolidated populations in dividing and nondividing GEPs, to microorganisms traversing breaches in the GEP plasma cell membrane. IBC formation was not a unique feature of H. pylori strains isolated from patients with chronic atrophic gastritis. The notion that adult mammalian epithelial progenitors can function as a repository for H. pylori broadens the view of host habitats available to this and perhaps other pathogens.

Retinoic acid stimulates the dynamics of mouse gastric epithelial progenitors

The gastric epithelial progenitors proliferate and undergo bipolar migration associated with their differentiation into pit, parietal, and zymogenic cell lineages. Retinoids have long been known to modulate proliferation and differentiation of various renewing epithelia, and the expression of their receptors has been demonstrated in the gastric mucosa. The aim of this study was to examine the effects of retinoic acid on progenitor cell proliferation and cell lineage formation in the mouse stomach. By using subcutaneously inserted osmotic pumps, mice were continuously infused with all-trans retinoic acid (5 mg/kg per day) for 3 days. To label S-phase cells and their progeny, bromodeoxyuridine was administered for different time intervals. Analysis of gastric mucosal tissues of retinoic acid-treated mice revealed a significant increase in the number of S-phase progenitor cells and an enhancement in the production of their progeny. The life span of pit cells was reduced, and their apoptosis became apparent at the luminal surface. Immunofluoresence probing of pit, parietal and enteroendocrine cell lineages in control and retinoic acid-treated mice showed no significant change in their labeling pattern. However, there was an increase in the labeled gland area of zymogenic cells. In conclusion, 3-day treatment of retinoic acid enhances the proliferation of gastric epithelial progenitors and the dynamics of their progeny.

Trefoil factor 1 is required for the commitment programme of mouse oxyntic epithelial progenitors

BACKGROUND

Trefoil factor 1 (TFF1/pS2) is a major secretory product of the stomach and TFF1 knockout mice constantly develop adenomas and occasional carcinomas in the pyloric antrum.

AIM

To analyse the role of TFF1 in the differentiation of gastric epithelial cell lineages using oxyntic mucosae from normal and TFF1 knockout mice.

METHODS

The various cell lineages were labelled using specific markers of pit, neck, parietal, and enteroendocrine cells. Patterns of TFF1, TFF2, and TFF3 expressions were defined using western blotting, immunohistochemistry, and/or immunogold electron microscopy.

RESULTS

In normal mice, starting from postnatal day 1 (P1), TFF1 and TFF2 were produced by mucus secreting cells of the developing epithelium. At P7, TFF3 expression occurred in pit and parietal cells. When oxyntic glands were compartmentalised, at P21 and in older mice, TFF1 and TFF2 were expressed in pit and neck cells, respectively, and TFF3 was no longer in parietal cells but became a feature of zymogenic cells. In TFF1 deficient mice, alteration of oxyntic epithelial differentiation became obvious at P21, showing significant amplification of pit cells at the expense of parietal cells. At the molecular level, lack of TFF1 induced dramatic inhibition of TFF2 expression and more precocious TFF3 expression.

CONCLUSION

In the oxyntic mucosa, all three TFFs are produced in a lineage specific manner and TFF1 is essential in maintaining the normal commitment programme of epithelial progenitors.

A transgenic mouse model of metastatic carcinoma involving transdifferentiation of a gastric epithelial lineage progenitor to a neuroendocrine phenotype

Human neuroendocrine cancers (NECs) arise in various endoderm-derived epithelia, have diverse morphologic features, exhibit a wide range of growth phenotypes, and generally have obscure cellular origins and ill-defined molecular mediators of initiation and progression. We describe a transgenic mouse model of metastatic gastric cancer initiated by expressing simian virus 40 large tumor antigen (SV40 TAg), under control of regulatory elements from the mouse Atp4b gene, in the progenitors of acid-producing parietal cells. Parietal cells normally do not express endocrine or neural features, and Atp4b-Cre bitransgenic mice with a Cre reporter confirmed that the Atp4b regulatory elements are not active in gastric enteroendocrine cells. GeneChip analyses were performed on laser capture microdissected SV40 TAg-expressing cells in preinvasive foci and invasive tumors. Genes that distinguish invasive from preinvasive cells were then hierarchically clustered with DNA microarray datasets obtained from human lung and gastric cancers. The results, combined with immunohistochemical and electron microscopy studies of Apt4b-SV40 TAg stomachs, revealed that progression to invasion was associated with transdifferentiation of parietal cell progenitors to a neuroendocrine phenotype, and that invasive cells shared molecular features with NECs arising in the human pulmonary epithelium, including transcription factors that normally regulate differentiation of various endocrine lineages and maintain neural progenitors in an undifferentiated state. The 399 mouse genes identified as regulated during acquisition of an invasive phenotype and concomitant neuroendocrine transdifferentiation, plus their human orthologs associated with lung NECs, provide a foundation for molecular classification of NECs arising in other tissues and for genetic tests of the molecular mechanisms underlying NEC pathogenesis.

Retinol enhances differentiation of the gastric parietal cell lineage in developing rabbits

In the gastric glands, parietal cells are the targets for anti-ulcer drugs because they contain the proton pump or HK-ATPase responsible for acid secretion. Little is known about factors influencing developmental expression and activity of HK-ATPase. In this study, the parietal cell lineage was investigated in rabbits at post-natal days 0 (P0) to P60 by using morphological and biochemical methods. Immunohistochemical and ultrastructural studies show that the HK-ATPase-expressing cells that appear at P0 and P3 are pre-parietal cells. However, terminally differentiated, mature parietal cells make their appearance at P7. These data correlate with the activity of HK-ATPase, measured as K(+)-dependent hydrolysis of p-nitrophenyl phosphate. Three-day-retinol treatment of P3-P30 rabbits induced an increase in the (i) production of parietal cells, (ii) intensity of the HK-ATPase immunostaining per cell, (iii) activity of HK-ATPase and (iv) amount of HK-ATPase protein measured by Western blotting. In conclusion, retinol upregulates the development of HK-ATPase in rabbits, perhaps due to precocious acceleration of the differentiation program of parietal cell lineage.

Defining epithelial cell progenitors in the human oxyntic mucosa

In the human stomach, the oxyntic epithelium includes numerous tubular invaginations consisting of short pits opening into long glands. The pit is lined by pit cells, whereas the gland is composed of three regions: the base, containing zymogenic cells; the neck, containing neck cells; and the isthmus, composed of little known immature cells and of parietal cells, which are also scattered through the neck and base. The aim of this study was to examine the ultrastructure of the immature cells and to determine their relation to mature cells. To do so, normal oxyntic mucosal biopsies from subjects ranging from 20-43 years old were fixed in aldehydes and postfixed in reduced osmium for electron microscopy and morphometric analysis. The immature cells were sorted out into four classes, whose roles were clarified by comparison with the thoroughly investigated mouse oxyntic epithelium. The first class was composed of the least differentiated immature cells, which were rare and characterized by minute, dense, or cored secretory granules and were accordingly named mini-granule cells. Their function was not clarified. The second class consisted of pre-pit cells, which were characterized by few dense mucous granules and give rise to pit cells that ascend the pit wall and, after reaching the luminal surface, die or are extruded. Both pre-pit and pit cells underwent continuous renewal and, therefore, together constituted a renewal system referred to as pit cell lineage. The third class, or pre-neck cells, characterized by cored secretory granules, give rise to neck cells that descend toward the base region and differentiate further into pre-zymogenic cells, which finally become zymogenic cells. The latter eventually degenerate and die. Thus pre-neck cells and their progeny constitute a renewing system, designated zymogenic cell lineage. The fourth class, or pre-parietal cells, characterized by long microvilli and few tubulovesicles, differentiate into parietal cells that descend along the neck and base regions and eventually degenerate and die. Pre-parietal and parietal cells represent a renewing system referred to as parietal cell lineage. While the origin of the last three classes of progenitor cells has not been elucidated, it is likely that they arise either from an unidentified multipotential stem cell, possibly the mini-granule cell itself, or from the mitotic activity of pre-pit and pre-neck cells. In conclusion, the human oxyntic epithelium is composed of continually renewing cells organized in distinct cell lineages.

Growth inhibition of MCF-7 human breast cancer cells by progesterone is associated with cell differentiation and phosphorylation of Akt protein

Progesterone inhibits the proliferation of normal breast epithelial cells as well as breast cancer cells. The molecular mechanisms of this inhibition are not fully understood. The purpose of this study was to investigate the capacity of progesterone to induce apoptosis and to alter the activity of a key regulator of cell growth and differentiation, the Akt protein. We show here that (i) growth inhibition of breast cancer cells by progesterone is due to the induction of cell differentiation and not to apoptosis; (ii) progesterone activates the PI3-kinase/Akt pathway as shown by the increase in the phosphorylation of Akt protein; (iii) inhibiting PI3-kinase/Akt pathway with LY294002 causes stimulation of apoptosis; and (v) progesterone enhances LY294002 induced-growth inhibition and apoptosis. These results suggest that progesterone may protect breast cancer cells from apoptosis by altering PI3-kinase activity and that MCF-7 cells become more sensitive to progesterone and die by apoptosis upon inhibition of the PI3-kinase/Akt pathway.

Trefoil factor 1 (TFF1/pS2) deficiency activates the unfolded protein response

BACKGROUND

The trefoil factor 1 (TFF1/pS2) is a secreted gastrointestinal peptide that is often altered or lost in human gastric cancers. Consistently, mouse TFF1 deficiency leads to antropyloric tumors.

MATERIALS AND METHODS

To investigate the gene expression alterations in response to the lack of TFF1, we performed differential expression analyses of TFF1 null antropyloric tumors using an array containing 588 cDNAs.

RESULTS

Using total and enriched probes, 22 genes were found to be up-regulated. The identification of the genes for endoplasmic reticulum (ER)-resident GRP78, ERp72, and p58IPK proteins connected TFF1 deficiency to the unfolded protein response (UPR). Accordingly, CHOP10, a transcription factor induced early in response to ER stress, and the pleiotropic Clusterin, involved in protein folding, were also overexpressed. Northern blot analyses of 8 weeks and 1 year TFF1 null tumors confirmed that GRP78, ERp72, p58IPK, CHOP10, and Clusterin overexpression is a common and permanent feature shared by all TFF1 null antropyloric tumors. Finally, consistent with UPR, ultrastructural analyses showed that tumor rough ER was enlarged and contained dense material, supporting the hypothesis that TFF1 deficiency leads to the accumulation of misfolded proteins in the ER.

CONCLUSION

Together, our data provide the first evidence of a relationship between a member of the TFF family and the ER machinery. Whereas to date TFF1 is believed to act as an extracellular molecule, our results suggest a possible additional function for TFF1 in protein folding and/or secretion.

Trefoil factor 1 (TFF1/pS2) deficiency activates the unfolded protein response

BACKGROUND

The trefoil factor 1 (TFF1/pS2) is a secreted gastrointestinal peptide that is often altered or lost in human gastric cancers. Consistently, mouse TFF1 deficiency leads to antropyloric tumors.

MATERIALS AND METHODS

To investigate the gene expression alterations in response to the lack of TFF1, we performed differential expression analyses of TFF1 null antropyloric tumors using an array containing 588 cDNAs.

RESULTS

Using total and enriched probes, 22 genes were found to be up-regulated. The identification of the genes for endoplasmic reticulum (ER)-resident GRP78, ERp72, and p58IPK proteins connected TFF1 deficiency to the unfolded protein response (UPR). Accordingly, CHOP10, a transcription factor induced early in response to ER stress, and the pleiotropic Clusterin, involved in protein folding, were also overexpressed. Northern blot analyses of 8 weeks and 1 year TFF1 null tumors confirmed that GRP78, ERp72, p58IPK, CHOP10, and Clusterin overexpression is a common and permanent feature shared by all TFF1 null antropyloric tumors. Finally, consistent with UPR, ultrastructural analyses showed that tumor rough ER was enlarged and contained dense material, supporting the hypothesis that TFF1 deficiency leads to the accumulation of misfolded proteins in the ER.

CONCLUSION

Together, our data provide the first evidence of a relationship between a member of the TFF family and the ER machinery. Whereas to date TFF1 is believed to act as an extracellular molecule, our results suggest a possible additional function for TFF1 in protein folding and/or secretion.

Characterization of the rabbit gastric epithelial lineage progenitors in short-term culture

Little is known about the mechanisms that establish and maintain the proliferation and differentiation programs of the gastric epithelium. This is largely due to the complexity of the gastric epithelial units and the presence of the different epithelial lineage progenitors among heterogeneous populations of various mature cell types. This study is undertaken to establish an in vitro system highly enriched for gastric epithelial lineage progenitors. By using adult male rabbits, a simple method of isolating gastric epithelial cell fractions enriched in lineage progenitors was applied. Cultured cells labeled with bromodeoxyuridine were characterized by using lectin and immunohistochemical studies at light- and electronmicroscopical levels. Analysis of primary cultures derived from the progenitor cell region of the epithelial units revealed that this system can support the proliferation and some of the differentiation programs of the progenitor cells. Cultured cells can be maintained for up to 5 days, while retaining most of the morphological features, molecular markers, and dynamic behavior of gastric epithelial progenitors. Differential cell counts at 1-day culture revealed that, while the undifferentiated progenitors formed about 30% of all attached cells, pre-pit, pit, and preparietal cells represented about 30%, 10%, and 2%, respectively. By 3 days, the increase in the percentage of pit and preparietal cells up to 25% and 9%, respectively, reflected their production in vitro. In conclusion, we have established a culture system enriched for gastric epithelial lineage progenitors that would hopefully allow the identification of factors and mechanisms involved in controlling their proliferative activity and differentiation pathways.

Blocking of histamine H2 receptors enhances parietal cell degeneration in the mouse stomach

The effects of the histamine H2 receptor antagonist, ranitidine, on parietal cell lineage was studied in the mouse stomach by using light and electron microscopy techniques. Mice were continuously infused for 15, 30, and 42 hr with ranitidine. Semithin sections examined under the light microscope revealed spherical light areas in the cytoplasm of parietal cells which in thin sections under the electron microscope appeared to be vacuoles. Cells were categorized as normal, altered and damaged. While altered cells were characterized by dilated canaliculi and vacuoles, the damaged cells showed signs of necrosis or apoptosis. In control mice, altered and damaged parietal cells were consistently few and only found in the pit or base regions of the epithelial units. After 15-hr-treatment with ranitidine, 40% of the parietal cells were altered. After 30 hr infusion, altered parietal cells became 53% of the examined population, and after 42 hr, 72% of the parietal cells were affected (42% altered and 30%, damaged). The gradual increase in parietal cell vacuolation was associated with an increase in the census of pre-parietal cells. Some mice were allowed to recover from treatment for 4 days. The appearance of normal parietal cells and disappearance of damaged cells was observed and the gastric glands became morphologically normal. In conclusion, inhibiting acid secretion by blocking the histamine H2 receptors, enhanced not only the degenerative elimination of parietal cells but also the production of pre-parietal cells and thus, the recovery of the population was prompt.

Identification and characterization of a novel gastric peptide hormone: the motilin-related peptide

BACKGROUND & AIMS

This study looked for new proteins with expression restricted to the gastric epithelium that may provide insight to the differentiation and function of the gastric unit.

METHODS

A novel complementary DNA was isolated and sequenced, and its expression was examined in mouse tissues at both messenger RNA and protein levels. Subcellular localization was studied using immunoelectron microscopy. The posttraductional processing of the protein was analyzed in vitro by protein microsequencing and in vivo by Western blotting.

RESULTS

We identified a novel protein that is mainly expressed by the secretory granules of the stomach enteroendocrine cells. This protein has sequence similarity with prepromotilin, the precursor of the motilin hormone and the motilin-associated peptide. As for the prepromotilin, a posttraductional maturation leads to a secreted peptide that is further cleaved at a dibasic site and gives rise to the motilin-related peptide (MTLRP) and MTLRP-associated peptide.

CONCLUSIONS

We have identified and characterized a novel gene encoding the preproMTLRP protein. MTLRP presents similarity to motilin and is specifically expressed by enteroendocrine cells of the stomach and therefore represents a novel hormone.

Vitamin A deficiency in mice enhances the colonic level of purine enzyme activity

BACKGROUND

Vitamin A is an important nutritional factor that regulates normal growth and functions of epithelial cells of the gastrointestinal tract.

OBJECTIVE

The objective of this study was to examine the role of vitamin A on the histological and biochemical changes in the colon of mice.

METHODS

To address this issue, vitamin A deficiency (VAD) was developed in mice by placing them on a VAD diet from weaning up to 120-170 days. Infiltration of inflammatory cells in the colon was determined histologically. Activities of adenosine deaminase, adenylate deaminase, purine nucleoside phosphorylase and myeloperoxidase were determined.

RESULTS

VAD in mice induced a significant increase in the number of mast cells per 100 crypts. There was also an abundance of other connective tissue cells such as plasma cells, lymphocytes and neutrophils around the crypts in the lamina propria. The colonic activity of adenosine deaminase and adenylate deaminase was increased due to VAD, whereas purine nucleoside phosphorylase activity remained unchanged. Immunohistochemical analysis showed an increased expression of adenosine deaminase in VAD mice colon. The increase in myeloperoxidase activity was not statistically significant.

CONCLUSIONS

VAD causes upregulation of purine enzyme, which together with an increased number of inflammatory cells might exacerbate colonic injuries in VAD condition.

Lineage commitment and maturation of epithelial cells in the gut

The dynamic concepts of gut epithelial cell populations which heralded the era of modern gut cell biology have been generally substantiated by recent studies and are still being correlated with functional properties. Multipotent stem cells are anchored in specific locations along the gut epithelium where decisions concerning proliferation and differentiation/migration pathways are made. Stem cells give rise to lineage precursors which transform into transit cells and sequentially express lineage specific features during their differentiation program. Morphologically and functionally mature cells along the gut epithelium are dynamically heterogeneous. 1) The squamous lineage of the esophagus forms a stratified epithelium which has an average turnover time of about 7. 5 days. 2) In the stomach, the oxyntic pit-gland unit includes pit, zymogenic and parietal cells which respectively migrate outwards, inwards, and in both directions; their turnover times average 3, 194 and 54 days, respectively. 3) The mucous units of the pyloric antrum are populated by pit cells which migrate outwards and gland cells which migrate inwards; their turnover times are about 3 and 1-60 days, respectively. 4) In the crypt-villus units of the small intestine, while both absorptive and goblet cells migrate outwards and for each the turnover time is about 3 days, Paneth cells migrate inwards and their turnover time is about 15 days. 5) In the crypts of the descending colon, both vacuolated-columnar and goblet cells migrate outwards and for each the turnover time is about 5 days. The ascending colon has an additional cell type called deep crypt secretory cells which migrate inwards and their turnover time is about 14-21 days. Finally, while the factors maintaining the gut epithelium in a steady state remain to be elucidated, this epithelium represents a remarkable system for studying the biological features of stem cells and their hierarchies.

Helicobacter pylori attaches to NeuAc alpha 2,3Gal beta 1,4 glycoconjugates produced in the stomach of transgenic mice lacking parietal cells

Helicobacter pylori infection of the human stomach is associated with altered acid secretion, loss of acid-producing parietal cells, and, in some hosts, adenocarcinoma. We have used a transgenic mouse model to study the effects of parietal cell ablation on H. pylori pathogenesis. Ablation results in amplification of the presumptive gastric epithelial stem cell and its immediate committed daughters. The amplified cells produce sialylated oncofetal carbohydrate antigens that function as receptors for H. pylori adhesins. Attachment results in enhanced cellular and humoral immune responses. NeuAc alpha 2,3Gal beta 1,4 glycoconjugates may not only facilitate persistent H. pylori infection in a changing gastric ecosystem, but by promoting interactions with lineage progenitors and/or initiated cells contribute to tumorigenesis in patients with chronic atrophic gastritis.