Valence coding in amygdala circuits

The neural mechanisms underlying emotional valence are at the interface between perception and action, integrating inputs from the external environment with past experiences to guide the behavior of an organism. Depending on the positive or negative valence assigned to an environmental stimulus, the organism will approach or avoid the source of the stimulus. Multiple convergent studies have demonstrated that the amygdala complex is a critical node of the circuits assigning valence. Here we examine the current progress in identifying valence coding properties of neural populations in different nuclei of the amygdala, based on their activity, connectivity, and gene expression profile.

What is memory? The present state of the engram

The mechanism of memory remains one of the great unsolved problems of biology. Grappling with the question more than a hundred years ago, the German zoologist Richard Semon formulated the concept of the engram, lasting connections in the brain that result from simultaneous “excitations”, whose precise physical nature and consequences were out of reach of the biology of his day. Neuroscientists now have the knowledge and tools to tackle this question, however, and this Forum brings together leading contemporary views on the mechanisms of memory and what the engram means today.

Memory. Engram cells retain memory under retrograde amnesia

Memory consolidation is the process by which a newly formed and unstable memory transforms into a stable long-term memory. It is unknown whether the process of memory consolidation occurs exclusively through the stabilization of memory engrams. By using learning-dependent cell labeling, we identified an increase of synaptic strength and dendritic spine density specifically in consolidated memory engram cells. Although these properties are lacking in engram cells under protein synthesis inhibitor-induced amnesia, direct optogenetic activation of these cells results in memory retrieval, and this correlates with retained engram cell-specific connectivity. We propose that a specific pattern of connectivity of engram cells may be crucial for memory information storage and that strengthened synapses in these cells critically contribute to the memory retrieval process.

Island cells control temporal association memory

Episodic memory requires associations of temporally discontiguous events. In the entorhinal-hippocampal network, temporal associations are driven by a direct pathway from layer III of the medial entorhinal cortex (MECIII) to the hippocampal CA1 region. However, the identification of neural circuits that regulate this association has remained unknown. In layer II of entorhinal cortex (ECII), we report clusters of excitatory neurons called island cells, which appear in a curvilinear matrix of bulblike structures, directly project to CA1, and activate interneurons that target the distal dendrites of CA1 pyramidal neurons. Island cells suppress the excitatory MECIII input through the feed-forward inhibition to control the strength and duration of temporal association in trace fear memory. Together, the two EC inputs compose a control circuit for temporal association memory.

Regional specificity of synaptic plasticity deficits in a knock-in mouse model of DYT1 dystonia

DYT1 dystonia is a movement disorder caused by a deletion in the C-terminal of the protein torsinA. It is unclear how torsinA mutation might disrupt cellular processes encoding motor activity, and whether this impairment occurs in specific brain regions. Here, we report a selective impairment of corticostriatal synaptic plasticity in knock-in mice heterozygous for Δ-torsinA (Tor1a(+/Δgag) mice) as compared to controls (Tor1a(+/+) mice). In striatal spiny neurons from Tor1a(+/Δgag) mice, high-frequency stimulation failed to induce long-term depression (LTD), whereas long-term potentiation (LTP) exhibited increased amplitude. Of interest, blockade of D2 dopamine receptors (D2Rs) increased LTP in Tor1a(+/+) mice to a level comparable to that measured in Tor1a(+/Δgag) mice and normalized the levels of potentiation across mouse groups. A low-frequency stimulation (LFS) protocol was unable to depotentiate corticostriatal synapses in Tor1a(+/Δgag) mice. Muscarinic M1 acetylcholine receptor (mAChR) blockade rescued plasticity deficits. Additionally, we found an abnormal responsiveness of cholinergic interneurons to D2R activation, consisting in an excitatory response rather than the expected inhibition, further confirming an imbalance between dopaminergic and cholinergic signaling in the striatum. Conversely, synaptic activity and plasticity in the CA1 hippocampal region were unaltered in Tor1a(+/Δgag) mice. Importantly, the M1 mAChR-dependent enhancement of hippocampal LTP was unaffected in both genotypes. Similarly, both basic properties of dopaminergic nigral neurons and their responses to D2R activation were normal. These results provide evidence for a regional specificity of the electrophysiological abnormalities observed and demonstrate the reproducibility of such alterations in distinct models of DYT1 dystonia.

Creating a false memory in the hippocampus

Memories can be unreliable. We created a false memory in mice by optogenetically manipulating memory engram-bearing cells in the hippocampus. Dentate gyrus (DG) or CA1 neurons activated by exposure to a particular context were labeled with channelrhodopsin-2. These neurons were later optically reactivated during fear conditioning in a different context. The DG experimental group showed increased freezing in the original context, in which a foot shock was never delivered. The recall of this false memory was context-specific, activated similar downstream regions engaged during natural fear memory recall, and was also capable of driving an active fear response. Our data demonstrate that it is possible to generate an internally represented and behaviorally expressed fear memory via artificial means.

Differential expression of e-cadherin in normal, metaplastic and dysplastic esophageal mucosa - a putative biomarker

Barrett's mucosa is a potentially premalignant columnar lined metaplastic epithelium in the oesophagus about which little is known regarding maintenance of cell adhesion. In this regard E-Cadherin (E-cad) is a 120 kDa polypeptide present in all epithelial tissues and it is the prime mediator of cell-cell interactions. An immunohistochemical technique utilised the monoclonal antibody HECD-1 to evaluate E-cad expression in microwave treated, paraffin embedded sections from 120 patients. The phenotype of the specimens from the patients were metaplastic [41] and dysplastic mucosa [24], invasive squamous carcinoma [15] and adenocarcinoma [18] and corresponding metastatic lesions [10] as well as 12 specimens of normal oesophageal mucosae. Surface expression was high in non-metaplastic tissue and in non-dysplastic metaplasia but was reduced extensively in dysplasia. In addition in squamous carcinoma and adenocarcinoma E-cad was characteristically expressed in the cytoplasm and this was associated with poor morphological differentiation. SDS-PAGE gel protein analysis revealed the characteristic 120 kDa sized protein in normal squamous oesophageal tissue. In Barrett's metaplastic tissue and carcinoma, however, stronger bands at 108 kDa and 45 kDa were also present, suggesting either decreased glycosylation or a truncated protein in the metaplastic and neoplastic tissue, respectively. In conclusion changes in E-cad immunoreactivity and cellular localisation occur in premalignant metaplastic epithelium of the oesophagus. Further studies are in progress to evaluate whether the abnormal E-cad protein reflects both loss of function and may be used as a biomarker in pre-malignant lesions.

Characterization of a Novel Oral Glucocorticoid System and Its Possible Role in Disease

Synthetic corticosteroids are used widely for the treatment of a variety of diseases of the mouth. However, little is known as to whether the oral mucosa is able to modulate the local concentration of active corticosteroids or to produce steroids de novo. This has important clinical implications, because tissue-specific regulation of glucocorticoids is a key determinant of the clinical efficacy of these drugs. In the present study, we show that oral fibroblasts and keratinocytes expressed ACTH receptor (MC2R), glucocorticoid receptor (GR), and 11β-hydroxysteroid dehydrogenases (11β-HSDs). Unlike keratinocytes, fibroblasts lacked 11β-HSD2 and could not effectively deactivate exogenously administered cortisol. However, both cell types were able not only to activate cortisone into the active form cortisol, but also to synthesize cortisol de novo following stimulation with ACTH. 11β-HSD2, the enzyme controlling cortisol deactivation, exhibited different patterns of expression in normal (squamous epithelium and salivary glands) and diseased oral mucosa (squamous cell carcinoma and mucoepidermoid carcinoma). Blocking of endogenous cortisol catabolism in keratinocytes with the 11β-HSD2 inhibitor 18β-glycyrrhetinic acid mimicked the effect of exogenous administration of hydrocortisone and partially prevented the detrimental effects induced by pemphigus vulgaris sera. Analysis of the data demonstrates that a novel, non-adrenal glucocorticoid system is present in the oral mucosa that may play an important role in disease.

Neural circuits underlying the generation of theta oscillations

Theta oscillations represent the neural network configuration underlying active awake behavior and paradoxical sleep. This major EEG pattern has been extensively studied, from physiological to anatomical levels, for more than half a century. Nevertheless the cellular and network mechanisms accountable for the theta generation are still not fully understood. This review synthesizes the current knowledge on the circuitry involved in the generation of theta oscillations, from the hippocampus to extra hippocampal structures such as septal complex, entorhinal cortex and pedunculopontine tegmentum, a main trigger of theta state through direct and indirect projections to the septal complex. We conclude with a short overview of the perspectives offered by technical advances for deciphering more precisely the different neural components underlying the emergence of theta oscillations.

The London APP mutation (Val717Ile) associated with early shifting abilities and behavioral changes in two Italian families with early-onset Alzheimer's disease

BACKGROUND/AIMS

Mutations in the amyloid precursor protein gene were the first to be recognized as a cause of Alzheimer's disease (AD).

METHODS

We describe 2 Italian families showing the missense mutation in exon 17 of the amyloid precursor protein gene on chromosome 21 (Val717Ile), known as London mutation.

RESULTS

In 1 family, this mutation was responsible for AD in 3 out of 7 siblings and it is also present in a fourth sibling who has only shown signs of executive dysfunction so far. Two subjects of the other family with AD diagnosis were carriers of the same mutation.

CONCLUSION

All AD subjects showed a cognitive profile characterized by early impairment in long-term memory, shifting abilities and affective symptoms beginning in the fifth decade of life.

Enhanced expression of the neuronal K+/Cl- cotransporter, KCC2, in spontaneously depressed Flinders Sensitive Line rats

We used Flinder Sensitive Line (FSL) rats, a genetic model of unipolar depression, to examine whether changes in central GABAergic transmission are associated with a depressed phenotype. FSL rats showed an increased behavioral response to low doses of diazepam, as compared to either Sprague Dawley (SD) or Flinder Resistant Line (FRL) rats used as controls. Diazepam at a dose of 0.3 mg/kg, i.p., induced a robust impairment of motor coordination in FSL rats, but was virtually inactive in SD or FRL rats. The increased responsiveness of FSL rats was not due to changes in the brain levels of diazepam or its active metabolites, or to increases in the number or affinity of benzodiazepine recognition sites, as shown by the analysis of [(3)H]-flunitrazepam binding in the hippocampus, cerebral cortex or cerebellum. We therefore examined whether FSL rats differed from control rats for the expression levels of the K(+)/Cl(-) cotransporter, KCC2, which transports Cl(-) ions out of neurons, thus creating the concentration gradient that allows Cl(-) influx through the anion channel associated with GABA(A) receptors. Combined immunoblot and immunohistochemical data showed a widespread increase in KCC2 expression in FSL rats, as compared with control rats. The increase was more prominent in the cerebellum, where KCC2 was largely expressed in the granular layer. These data raise the interesting possibility that a spontaneous depressive state in animals is associated with an amplified GABAergic transmission in the CNS resulting from an enhanced expression of KCC2.

The pea aphid phylome: a complete catalogue of evolutionary histories and arthropod orthology and paralogy relationships for Acyrthosiphon pisum genes

Phylogenetic analyses serve many purposes, including the establishment of orthology relationships, the prediction of protein function and the detection of important evolutionary events. Within the context of the sequencing of the genome of the pea aphid, Acyrthosiphon pisum, we undertook a phylogenetic analysis for every protein of this species. The resulting phylome includes the evolutionary relationships of all predicted aphid proteins and their homologues among 13 other fully-sequenced arthropods and three out-group species. Subsequent analyses have revealed multiple gene expansions that are specific to aphids and have served to transfer functional annotations to 4058 pea aphid genes that display one-to-one orthology relationships with Drosophila melanogaster annotated genes. All phylogenies and alignments are accessible through the PhylomeDB database. Here we provide a description of this dataset and provide some examples on how can it be exploited.

The actin-bundling protein fascin is overexpressed in colorectal adenomas and promotes motility in adenoma cells in vitro

Background:

Fascin is overexpressed in many cancers, including colorectal, but its role in the malignant transformation of benign colorectal adenomas is unclear.

Methods:

Immunohistochemical analysis of fascin expression was carried out in resected human colorectal adenoma specimens. The effects of forced overexpression of fascin on adenoma cell motility were also analysed.

Results:

We show fascin overexpression in adenomas increasing with tumour size, histological type, and degree of dysplasia and increased cell motility in adenoma cell lines following fascin transfection.

Conclusion:

These data suggest an important role for fascin in the malignant progression of colorectal tumours.

Inhibition of COX-2 with NS-398 decreases colon cancer cell motility through blocking epidermal growth factor receptor transactivation: possibilities for combination therapy

The use of non-steroidal anti-inflammatory drugs has proved of great interest in the prevention and treatment of colorectal cancer, although their precise mechanisms of action remain unclear. Overexpression of cyclooxygenase-2 (COX-2) and subsequent prostaglandin production promote metastasis and have been shown to increase cell motility in vitro.

OBJECTIVE

We have aimed to elucidate whether specific inhibition of COX-2 with NS-398 (NS-398 is a selective inhibitor of COX-2) would be able to inhibit motility of colorectal cancer cells and whether this was modulated through epidermal growth factor receptor (EGFR) transactivation.

MATERIALS AND METHODS

A transwell filter assay was used to study cell motility. Expression of COX-2, EGFR phosphorylation and prostaglandin E(2) (PGE(2)) receptors were assessed by Western blot analysis and reverse transcriptase-polymerase chain reaction. PGE(2) concentrations after NS-398 treatment were estimated by enzyme immunoassay.

RESULTS

Treatment with NS-398 significantly reduced PGE(2) levels and reduced cell migration in the HT29 and HCA7 colorectal carcinoma cell lines and this effect was rescued by addition of PGE(2). Furthermore, specific inhibition of COX-2 with NS-398 reduced EGFR phosphorylation in colorectal cancer cells. Direct inhibition of EGFR activity with AG1478 reduced PGE(2)-stimulated motility, clearly demonstrating that PGE(2 )acts via the EGFR-signalling pathway. The novel combination of NS-398 and AG1478 dramatically reduced migration of colorectal cancer cells.

CONCLUSION

The data presented indicate that the use of NS-398 in chemoprevention and adjuvant therapy for colorectal cancer may work in part, through the inhibition of cell motility. Furthermore, our data suggest that the combined use of non-steroidal anti-inflammatory drugs with EGFR antagonists could be explored further for future use in the clinic.

Galactosilated dopamine increases attention without reducing activity in C57BL/6 mice

Different strategies can be used to carry dopamine into the brain such as L-Dopa precursors or galactosilated form of DA (GAL-DA). The aim of this study was to investigate whether GAL-DA would reduce hyperactivity and increase non-selective attention (NSA) in a mouse model of attention deficit hyperactivity disorder (ADHD), as, i.e. C57BL/6 as did in NHE rats. Here we report that GAL-DA increases NSA in a spatial novelty in C57BL/6 mice. They received a single i.p. injection of GAL-DA (10 mg/kg or 100 mg/kg) or equimolar galactose vehicle. Another mouse strain the Swiss albino was introduced as inbred control group. Three hours after last injection mice were tested in a Làt-maze for 30-min. Behaviour was analyzed for horizontal (traveled distance) and vertical activity (orienting frequency and scanning durations) which shares cognitive and non-cognitive nature, respectively. Ten milligram per kilograms of GAL-DA, increases scanning duration in C57BL/6 mice. Thus a low dose of GAL-DA increases NSA without reducing hyperactivity in this mouse model of ADHD.

Characterisation of adherens and tight junctional molecules in normal animal larynx; determining a suitable model for studying molecular abnormalities in human laryngopharyngeal reflux

BACKGROUND

The disruption of intercellular junctions in the larynx is a pathological feature of laryngopharyngeal reflux (LPR). Good experimental models are necessary to gain greater insight into the molecular mechanisms and alterations that result from abnormal exposure of the laryngeal epithelium to acid refluxate.

AIMS

To characterise laryngeal tissues from different species to determine the most suitable for use in experimental studies of LPR.

METHODS

Human and non-human laryngeal tissues (mouse, rat, guinea pig, porcine, and rabbit) were studied. Histological characterisation was performed by light microscopy. The expression and subcellular localisation of adherens junctional molecules (E-cadherin and beta catenin) was evaluated by immunohistochemistry, and tight junction molecules (occludin and zonula occludens 1 (ZO-1)) by western blotting. The ultrastructural features of porcine and human tissue were assessed by electron microscopy.

RESULTS

Porcine tissue revealed both respiratory-type and stratified squamous epithelium, as seen in the human larynx. The expression and subcellular localisation of the E-cadherin-catenin complex was detected in all species except mouse and rat. The pattern of ZO-1 and occludin expression was preserved in all species.

CONCLUSION

The expression of intercellular junctional complexes in porcine epithelium is similar to that seen in humans. These results confirm the suitability of these species to study molecular mechanisms of LPR in an experimental system.

Activated Akt expression in breast cancer: Correlation with p53, Hdm2 and patient outcome

Activation of protein kinase-B/Akt (pAkt) is mediated by oestrogen and involves HER-2 in vitro, to phosphorylate Hdm2 and influence p53 cytoplasmic localisation and degradation. Expression of all active Akt isoforms (pAkt) were examined, together with p53/Hdm2 subcellular expression in invasive ductal breast cancers (IDCs), to evaluate whether in vitro findings were related to clinical data and determine the effect on outcome. Immunohistochemical expression of serine 473 specific phosphorylated Akt (pAkt) isoforms (Akt-1,2,3) was evaluated in 97 patients, together with subcellular expression of p53/Hdm2. The results show that pAkt was evaluable in 95 patients with cytoplasmic expression in 81% and more likely to be associated with larger tumours (P=0.007), with no correlation with HER-2 expression. pAkt correlated with increasing levels of cytoplasmic p53 (P=0.025) and was associated with a reduced disease-free survival (P=0.04; univariate). In conclusion, pAkt has implications in breast cancer growth through mechanisms inactivating p53 with an association with immunohistochemical p53 expression, which is preferentially cytoplasmic. Despite in vitro associations, pAkt appears to be a variable marker of HER-2 expression.

Adhesion molecules: opportunities for modulation and a paradigm for novel therapeutic approaches in cancer

In the past decade, there have been major advances in the elucidation of processes underlying tumour invasion and metastasis, in which adhesion molecules play a critical role. These advances have revolutionised our ability to devise novel approaches for cancer treatment. This review gives an insight into the adhesion pathways, and highlights the current status of adhesion molecules as potential therapeutic targets.

Lectins: from basic science to clinical application in cancer prevention

Many physiological functions are attributable to lectin-carbohydrate interactions. Lectins are currently being studied for their ability to destroy tumour growth by binding to specific carbohydrate motifs on cancer cells. Cell-surface molecules, including growth factor receptors are often glycosylated, and lectins may act by binding to these. Certain lectins effect the proliferation of intestinal epithelial cells. This effect is cell-type and lectin specific and occurs in the intestine of intact animals, in human colonic explants and colorectal cancer cell lines. Lectins present in mammalian tissue are involved in cell-matrix adhesion, differentiation, lymphocyte circulation and immunomodulation. Mammalian lectins contribute to detection, diagnosis and prognosis of tumour cells, and can be targeted for therapy. New lectins of plant and mammalian origin that have one or more of these functions are currently being developed as tools that could be used to target tumour cells.

p14ARF expression in invasive breast cancers and ductal carcinoma in situ--relationships to p53 and Hdm2

Introduction

p14^ARF stabilises nuclear p53, with a variable expression of p14^ARF mRNA in breast cancers. In vitro, nuclear p14^ARF binds Hdm2 to block Hdm2-dependent nucleocytoplasmic shuttling of p53, which is required before cytoplasmic degradation of p53. p14^ARF is negatively regulated by p53 and through p53-independent pathways. No studies have yet examined levels of p14^ARF protein expression in breast cancer and their relationship to Hdm2/p53 immunoreactivity or subcellular localisation. Previously, immunohistochemical expression of cytoplasmic p14^ARF, p53 and Hdm2 has been described. HER-2 (c-erbB2/neu) predicts prognosis and interacts with the p14^ARF/Hdm2 pathway to inactivate p14^ARF and to influence Hdm2 activity and localisation. This study examined p14^ARF and p53/Hdm2 expression and subcellular localisation by using immunohistochemistry in a series of invasive ductal breast cancers (IDCs) with concomitant ductal carcinoma in situ (DCIS), to evaluate whether findings in vitro were related to clinicopathological parameters such as HER-2 and their effect on patient outcome.

Methods

The 4C6 anti-p14^ARF monoclonal antibody and Dako Envision Plus system were used to evaluate p14^ARF expression in 103 patients; p53/Hdm2 staining was performed.

Results

p14^ARF was evaluable in 96 patients, with nuclear p14^ARF expression (modified Quick-score ≥ 3) in 79% (n = 76) of IDCs and in associated DCIS in 74 patients. Cytoplasmic p14^ARF was detectable in 23 breast cancers. Nuclear and cytoplasmic p14^ARF showed no correlation with p53 subcellular immunoreactivity. Increasing levels of cytoplasmic p14^ARF were associated with nuclear and cytoplasmic Hdm2 expression (P < 0.001). Subcellular ARF expression was not associated with clinicopathological parameters, and although not an independent prognosticator, these preliminary findings suggest that cytoplasmic p14^ARF might be associated with a better overall survival (P = 0.09; log rank). The association between HER-2 positivity and nuclear p14^ARF (P = 0.038), as well as nuclear Hdm2 (P = 0.019), reflects the in vitro findings of HER-2 interaction with the ARF/Hdm2 pathway. Cytoplasmic p53 and Hdm2 expression might have biological implications, through an association of cytoplasmic p53 with increased tumour proliferation (P = 0.005), and an improved overall survival (P = 0.002, log rank) in cytoplasmic Hdm2-expressing tumours, that independently predict favourable overall survival (P = 0.02) and disease-free survival (P = 0.03).

Conclusions

Nuclear p14^ARF expression is similar in IDCs and DCIS and is associated with Hdm2 immunoreactivity. Nuclear p14^ARF and Hdm2 might be regulated by HER-2. Clearly, our findings in vivo suggest a complexity of p14^ARF/Hdm2 and p53 pathways in which consideration of cytoplasmic p14^ARF and Hdm2 might have tumorigenic implications.

Biochemical analysis and subcellular distribution of E-cadherin-catenin in adenocarcinomas of the gastro-oesophageal junction

BACKGROUND

Disturbances in the expression or structure of E-cadherin-catenin, a cell-cell adhesion complex, perturb its cell adhesive function.

MATERIALS AND METHODS

We studied the expression and distribution of the E-cadherin-catenin complex in 24 adenocarcinomas of the gastro-oesophageal junction (GOJ) by immunohistochemistry and Western blotting of the Triton X-100-soluble (membrane bound) and insoluble fractions (cytoskeleton bound).

RESULTS

Immunohistochemistry demonstrated redistribution of E-cadherin, alpha-, beta- and gamma-catenin from the membrane to the cytoplasm in 13/24 (54%), 18/24 (75%), 16/24 (67%) and 15/24 (63%) tumours, respectively. Five tumours showed nuclear localisation of beta-catenin. Western blotting showed redistribution between the TX-100 soluble and insoluble fraction of E-cadherin and the catenins in 5/11 (45%), 4/10 (40%), 5/11 (45%) and 5/11 (45%) tumours, respectively.

CONCLUSION

Loss of membrane bound E-cadherin-catenin is frequently observed in adenocarcinomas of the GOJ and this may reflect loss of function of the E-cadherin-catenin complex in these cancers.

Butyrate downregulates alpha2beta1 integrin: a possible role in the induction of apoptosis in colorectal cancer cell lines

BACKGROUND

Integrins mediate cell matrix adhesion and regulate cell growth and survival. In colonic epithelial cells, alpha(2)beta(1) integrin controls glandular differentiation and proliferation. Butyrate stimulates differentiation and induces apoptosis in vitro.

AIMS

We investigated whether butyrate induction of apoptosis was associated with perturbation of integrin mediated cell matrix adhesion.

METHODS

Three colonic cancer cell lines (SW1222, SW620, LS174T) were studied. Adhesion to extracellular matrix proteins, expression of alpha(2)beta(1) integrin, and apoptosis were studied in adherent cells after treatment with 4 mM butyrate.

RESULTS

Butyrate decreased the attachment to type I collagen in SW620 cells and type I and IV collagen in LS174T cells. The decreased cell attachment was associated with downregulation of alpha(2)beta(1) integrin and increased apoptosis in adherent cells. No changes in alpha(2)beta(1) expression or matrix adhesion were seen in SW1222 cells, which were also found to be less sensitive to butyrate induction of apoptosis. Downregulation of alpha(2)beta(1) integrin preceded the detection of apoptosis.

CONCLUSION

Apoptosis induced by butyrate is associated with downregulation of expression and functional activity of alpha(2)beta(1) integrin. Perturbation of cell matrix adhesion may be a novel mechanism by which butyrate induces apoptosis in colorectal cancer cells.

Prenatal elevation of endocannabinoids corrects the unbalance between dopamine systems and reduces activity in the Naples High Excitability rats

Several evidences suggest that endocannabinoids exert a neurotrophic effect on developing mesencephalic dopamine neurons. Since an altered mesocorticolimbic system seems to underlie hyperactivity and attention deficit in clinical and animal studies of attention deficit hyperactivity disorder (ADHD), prenatal elevation of anandamide has been induced in Naples high excitability (NHE) rats by inhibition of its reuptake. To this aim, pregnant NHE and random-bred females received a subcutaneous injection of AM-404 (1 mg/kg) or vehicle daily from E11 until E20. Young adult male offsprings were exposed to a spatial novelty (Làt-maze) for 30 min and the behavior was videotaped and analysed for indices of activity (travelled distance, rearing frequency) and attention (rearing duration). Moreover, morphological analysis of the brains was carried out that pertained to cytochrome oxydase as marker of metabolic activity and thyrosine hydroxylase as marker of the dopamine systems. The results indicate that prenatal AM-404 treatment significantly reduces activity by about 20% during the entire testing period and modifies the distribution of scanning times towards short duration episodes in the first part of the test only in NHE-treated rats. In addition, image analysis revealed a significant increase in relative optical density of TH+terminals in the dorsal striatum and substantia nigra of AM-404 treated NHE rats and minor changes in the dorsal cortex of AM-404 treated NRB rats. The data suggest a corrected unbalance between the two dopamine systems that apparently leads to reduced hyperactivity and modified scanning times in this animal model of ADHD. This, in turn, might open new strategies in the treatment of a subset of ADHD cases.

Abnormal alpha-catenin expression in invasive breast cancer correlates with poor patient survival

AIMS

alpha-Catenin is a member of the E-cadherin-catenin family of adhesion molecules whose role is essential for the function of the E-cadherin complex. In this study, we have evaluated the expression of alpha-catenin but also of the other catenins (beta-, gamma- and p120-catenin) and E-cadherin in invasive breast cancer and statistically analysed these expressions with known clinicopathological parameters, c-erbB-2 oncoprotein expression and patient survival.

METHODS AND RESULTS

Abnormal E-cadherin and beta-catenin expression, especially loss of expression, was associated with lobular histological type of breast carcinomas (P=0.03 and P=0.01, respectively). Abnormal E-cadherin and alpha-catenin expression was associated with high histological grade ductal carcinomas (P=0.01 and P=0.03, respectively). Abnormal E-cadherin and beta-catenin expression was correlated with lymph node metastases (P=0.02 and P=0.05, respectively), while abnormal alpha- and beta-catenin were correlated with the advanced stage of the disease (P=0.04 and P=0.05, respectively). Abnormal p120-catenin expression was associated with loss of PR (P=0.008). Survival analysis demonstrated a statistically significant association between abnormal alpha-catenin expression and poor patient survival (P=0.02). When survival analysis was performed according to the different patterns of abnormal expression, statistically significant associations were seen between cytoplasmic alpha- and beta-catenin expression and poor survival (P=0.006 and P=0.04, respectively).

CONCLUSIONS

alpha-Catenin, especially its cytoplasmic expression, seems to be a more sensitive prognostic marker than the other members of the E-cadherin complex in invasive breast cancer.

Molecular histology in the study of solid tumours

Dominant oncogenes and tumour suppressor gene abnormalities are crucial events in human cancer. Many molecular techniques are used to identify these abnormalities, including single strand conformational polymorphism, the polymerase chain reaction, cloning, and sequencing, although the biological relevance of these changes is not always apparent. Immuno-histochemistry (ICH) or western blotting of abnormal gene products can provide information about their cellular localisation and expression in neoplastic versus normal cells, and can sometimes give a clue to their function. For example, ICH has shown how loss of the intercellular adhesion molecule E-cadherin, or abnormal localisation from the cell membrane to the cytoplasm, correlates with a diffuse tumour phenotype and a less favourable clinical outcome. Similarly, ICH of beta-catenin (a protein that binds E-cadherin and is essential for its function) has shown abnormal cellular localisation in the nucleus in a variety of human malignancies; in particular, colorectal carcinomas, where abnormal forms of the adenomatous polyposis coli gene product cause nuclear and cytoplasmic sequestration of beta-catenin. Such studies show how morphological assessment can sometimes provide insight into molecular function and dysfunction in human malignancy.

Activity, non-selective attention and emotionality in dopamine D2/D3 receptor knock-out mice

In order to assess the role of dopamine (DA) D2 and D3 receptors in the modulation of behaviour, we analysed exploration in a spatial novelty in mouse model systems. Genetically engineered mice mutants have been used that carry normal, partial or no expression of D2R, D3R, or both D2R/D3R (double mutants) DA receptor subtypes. Adult male mice were exposed for 30 min to a Làte-maze. The behaviour was analysed for indices of activity, orienting (rearing frequency), scanning times (rearing duration) and defecation score (emotionality). D2R - / - and + / - as well as the D2R/D3R double homozygous mutants were less active than wild-type (WT) controls in travelled distance. In contrast D3R + / - were more active than WT mice in the first part of the test. As to orienting frequency, the D2R - / - were less active than WT during the entire test-period, whereas the D2 + / - mutants were less active than WT only in the second part of the test. Moreover, the D3R - / - and + / - mutants showed less and more rearing frequency than WT, respectively, during the entire test. Finally, the D2/D3R - / - double mutants were also less active than WT during the entire test period. As to scanning times, D2R + / - and - / - mutants were higher than WT during the entire test or only in the second part, respectively. The D3R + / - and - / - were not different from WT, whereas the D2/D3R - / - double mutants showed shorter scanning times only in the first part of the test. As to emotionality index, the defecation score, was lower only in D3R + / - mutants. Thus, the dopamine D2 and D3 receptor subtypes appear to be differentially involved in the modulation of activity, orienting and scanning phases of attention. Lastly double mutation experiments reveal an interaction between D2R and D3R with the former prevailing on the latter.

Environmental factors during postnatal period modify activity and non-selective attention in the Naples High-Excitability rat

The involvement of epigenetic factors in the phenotypic expression of the neural systems underlying activity and attentive processes has been investigated in an animal model of hyperactivity and attention-deficit, the Naples High-Excitability rat (NHE). To this aim, male NHE pups have been reared in small (four) or normal litter size (nine) during the first 4 weeks of postnatal life. Both groups underwent a differential handling procedure occurring once, twice or four times a week. After weaning (28 days), rats were housed in groups of two and tested as young adults for activity and non-selective attention in a spatial novelty situation for three consecutive tests at 24-h intervals. The behaviour was videotaped and analysed off line for the frequency of corner crossings and rearings and duration of rearings. The results indicate that the increased maternal care and high fat diet induced by the small litter size produced long lasting effects on activity and duration of rearing episodes that indexes non-selective attention. These effects were complex as differential handling was beneficial only at low stimulation level. Thus, these findings suggest that epigenetic factors acting during critical periods of post-natal development may interact with genetic determinants that in turn influence the maturation of the neural systems controlling activity, orienting and scanning time.

Selective inhibition of neuronal nitric oxide synthesis reduces hyperactivity and increases non-selective attention in the Naples High-Excitability rat

The involvement of neuron-derived NO in the process of orienting and scanning times (non-selective attention: NSA) towards environmental stimuli has been investigated in the Naples High-Excitability rat (NHE), a putative animal model of Hyperactivity and Attention Deficit (ADHD). To this aim, orienting and scanning times have been monitored by the frequency and duration of rearing episodes, respectively. Adult male NHE rats were tested in a novelty situation (Làt-maze) for 30 min following single or repeated injections of the non competitive inhibitor 7-Nitroindazole (7-NINA) of the neuronal isoform of the enzyme nitric oxide synthase (n-NOS). In the acute experiments, rats received a single injection of 7-NINA (1 mg/kg) intraperitonealy in a saline vehicle (exp. 1, fast release) or subcutaneously in a lipid carrier, dimethyl sulfoxide (DMSO; exp. 2, slow release) or the vehicles alone as controls 30 min before testing. In the repeated injection experiments, rats received a subcutaneus injection of 1 mg/kg in DMSO or DMSO alone daily for 14 days, and tested 24 h after the last injection (exp. 3, slow release). The results showed a significant differential effect of the drug that was dependent on the release rate, i.p. saline-diluted 7-NINA increased the duration of individual rearing episodes whereas, both single and repeated subcutaneous DMSO-carried 7-NINA exerted an opposite effect. Thus, selective inhibition of n-NOS by an allosteric inhibitor that increases arginine availability without displacing the inhibitor from n-NOS, strengthens the hypothesized role of NO in NSA. These findings may shed light on the mechanism of action of drug treatment of and be useful in the treatment of ADHD in children.

FGF-1 and FGF-2 regulate the expression of E-cadherin and catenins in pancreatic adenocarcinoma

E-cadherin is a transmembrane protein that mediates Ca2+-dependent cell-cell adhesion and is implicated in a number of biologic processes, including cell growth and differentiation, cell recognition and cell sorting during development. We have previously demonstrated that both cell-cell adhesion and invasion are modulated by fibroblast growth factor (FGF)-1 and FGF-2 in a panel of pancreatic adenocarcinoma cell lines (BxPc3, T3M4 and HPAF). Here, we examine further the role of FGFs in the expression and activation of the E-cadherin/catenin system. We demonstrate that both FGF-1 and FGF-2 upregulate E-cadherin and beta-catenin at the protein level in the BxPc3 and HPAF cell lines and modestly in T3M4 cells. FGF-1 and FGF-2 facilitate the association of E-cadherin and alpha-catenin with the cytoskeleton, as demonstrated by the increase in the detergent-insoluble fraction of E-cadherin in BxPc3 and HPAF cells. Since the correct function of the E-cadherin/catenin complex requires its association with the cytoskeleton, our data suggest that FGF-1 and FGF-2 contribute to the integrity and thus the function of the complex. Furthermore, FGFs facilitate the assembly of the E-cadherin/catenin axis. The effect is associated with elevation of tyrosine phosphorylation of E-cadherin, alpha-catenin, beta-4051 mu-catenin and gamma-catenin, but not p120ctn. These findings indicate that the E-cadherin/catenin system is a target of the FGF/FGFR system and that coordinated signals from both systems may determine the ultimate biologic responses.

The peroxisome proliferator-activated receptor γ is an inhibitor of ErbBs activity in human breast cancer cells

One of the most interesting recent developments in the nuclear receptor field has been the identification of natural and synthetic agonists of the peroxisome proliferator-activated receptor (PPAR) family, coupled with a growing recognition that the γ isoform (PPARγ) affects pathways important in a variety of human diseases. Here we show that the activation of PPARγ through the 15-deoxy-Δ-12,14-prostaglandin J2 (PG-J2) ligand causes a dramatic inhibition of ErbB-2 and ErbB-3 tyrosine phosphorylation caused by neuregulin 1 (NRG1) and neuregulin 2 (NRG2) in MCF-7 cells. This effect is accompanied by a very efficient blocking of ErbBs effects upon proliferation, differentiation and cell death in these cells. Preincubation of MCF-7 cells with PG-J2 before addition of NRG1 and NRG2 had a dramatic growth-suppressive effect accompanied by accumulation of cells in the G0/G1 compartment of the cell cycle, and a marked increase in apoptosis. NRG1 and NRG2 induce G1 progression, which was associated with stimulation of the phosphatidylinositol-3 kinase (PI 3-K) pathway, whereas survival was dependent on ERK1/ERK2 activation. Both pathways were inhibited by PG-J2. Furthermore, PG-J2 can abolish the NRG1 and NRG2-induced increase in anchorage-independent growth of these cells. PG-J2 also blocks phosphorylation of other receptor tyrosine kinases, such as IGF-IR, in MCF-7 cells, and suppress proliferation of other breast cancer cell lines. In summary, our data show a specific inhibitory action of PG-J2 on the activity of the ErbB receptors in breast cancer cells.

The potential role of abnormal E-cadherin and alpha-, beta- and gamma-catenin immunoreactivity in the determination of the biological behaviour of keratoacanthoma

BACKGROUND

Failure of E-cadherin and its associated proteins alpha-, beta- and gamma-catenin is believed to lead to disruption of cell-cell adhesion and to contribute to neoplasia.

OBJECTIVES

To determine the pattern of E-cadherin and alpha-, beta- and gamma-catenin immunostaining in keratoacanthoma (KA) and to evaluate its potential value in routine histopathology in differentiating KA with benign from that with malignant biological behaviour.

METHODS

We examined the expression of E-cadherin and alpha-, beta- and gamma-catenin in KA and correlated the histopathological features with the immunohistochemical findings. Next, we compared the immunohistochemical findings of KA with those found in malignant (squamous cell carcinoma, SCC) and benign (warts) lesions. In addition to the established histopathological criteria we used the Ki-67 index, a well-known marker of cell proliferation. Immunoperoxidase staining of E-cadherin and alpha-, beta- and gamma-catenin, and Ki-67 determination, were performed in paraffin-embedded sections of 12 KAs taken from archival material. On reviewing the histology, seven of the 12 KAs were characterized as 'classical' KA, and the rest as 'borderline' KA or KA resembling SCC. Additionally, 28 well, nine moderately and five poorly differentiated SCCs and 20 warts were examined.

RESULTS

Most 'classical' KAs (79-86%) showed normal membranous immunostaining and a low Ki-67 index. The remaining 'classical' KAs showed abnormal expression, in a staining pattern resembling that of well-differentiated SCC. All 'borderline' KAs showed a high Ki-67 index (> 40%) and abnormal expression of the adhesion molecules studied, identical to that of poorly differentiated SCC. Expression of E-cadherin and alpha-, beta- and gamma-catenin was found to be more frequently abnormal in 'borderline' KA compared with that in 'classical' KA (P < 0.05). Among E-cadherin and alpha-, beta- and gamma-catenin expression and Ki-67 index, only the expression of beta-catenin was more frequently found to be abnormal in total SCC than in total KA (P < 0.05). Expression of E-cadherin and alpha-, beta- and gamma-catenin was more frequently found to be abnormal in well-differentiated SCC than in 'classical' KA (P < 0.05). In total, as well as in 'classical' or 'borderline' KA, an agreement between expression of E-cadherin and of catenins was seen.

CONCLUSIONS

These findings suggest that E-cadherin and catenins may be very helpful in distinguishing between 'classical' and 'borderline' KA, as the expression of these adhesion molecules in 'classical' KA is identical to that found in normal epidermis, overlapping with well-differentiated SCC in some cases. In 'borderline' KA, expression of adhesion molecules is identical to that in poorly differentiated SCC.

FGF-1 and FGF-2 modulate the E-cadherin/catenin system in pancreatic adenocarcinoma cell lines

Fibroblast growth factors (FGFs) and fibroblast growth factor receptors (FGFRs) have been increasingly recognized to play an important role in the pathobiology of pancreatic malignancy. We have investigated the effects of FGF-1 and FGF-2 on the behaviour and adhesion properties of human pancreatic adenocarcinoma cell lines (BxPc3, T3M4 and HPAF) that were previously characterised for the expression of FGFRs. Here we show that exposure to FGF-1 and FGF-2 leads to significant and dose-dependent increase in E-cadherin-dependent cell-cell adhesion, tubular differentiation, and a reduced capacity to invade collagen gels. FGF stimulation produces phosphorylation of E-cadherin and beta-catenin on tyrosine residues, as well as increased E-cadherin localisation to the cytoplasmic membrane and association with FGFR1 demonstrable by coimmunoprecipitation. These results demonstrate that FGF-1 and FGF-2 may be involved in the regulation of cell adhesion, differentiation and invasion of pancreatic cancer.

Expression of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex correlates with the macroscopic appearance of early gastric cancer

E-cadherin and its associated cytoplasmic proteins, alpha-, beta-, and gamma-catenins, play an essential role in the control of epithelial differentiation. We have previously shown that loss or down-regulation of E-cadherin/catenin correlates with poor survival in advanced gastric adenocarcinoma. The aim of this study was to assess the expression of E-cadherin and catenins in early gastric cancers (EGCs). Immunohistochemical staining for E-cadherin and alpha-, beta-, and gamma-catenins was performed on 41 paraffin-embedded gastrectomy specimens of EGC using an indirect immunoperoxidase technique. The pattern of expression and cellular localization of the E-cadherin/catenin complex in tumour cells were correlated with the macroscopic appearance of the tumour according to the Japanese Endoscopic Society classification. The tumours were classified as follows: three type I (protruding) and 38 type II (superficial), of which ten were type IIa (elevated), one was type IIb (flat), and 27 were type IIc (depressed). E-cadherin and alpha-, beta-, and gamma-catenins were expressed at the cell-cell junctions in normal mucosa. Forty out of 41 tumours showed abnormal expression (loss of membranous immunoreactivity and/or nuclear staining) of at least one component of the E-cadherin catenin complex. Loss of E-cadherin immunoreactivity was more frequently seen in type IIb (1/1, 100%) and type IIc (27/27, 100%) than in type I (1/3, 33%) and type IIa (1/10, 10%) (p<0.01). Abnormal expression of E-cadherin and alpha-catenin was more frequently seen in diffuse-type than in intestinal type tumours (p<0.05). Abnormal immunoreactivity of beta- and gamma-catenin, including nuclear localization, was observed in 34% and 7.3% of tumours, respectively, but there was no significant correlation with tumour type or endoscopic appearance. In conclusion, abnormal expression of the E-cadherin/catenin complex occurs in EGC and seems to correlate with macroscopic appearances.

Expression patterns of beta-catenin in in situ and invasive breast cancer

BACKGROUND

beta-Catenin plays a central role in the E-cadherin/catenin cell-cell adhesion complex and is possibly involved in cellular signalling pathways. In this study, we evaluated the expression patterns of this molecule in in situ and invasive breast cancer.

METHODS

The expression of beta-catenin was evaluated in 121 breast cancer specimens by immunohistochemistry. Its relationship to clinicopathological features was also investigated.

RESULTS

Altered beta-catenin expression was found in 68% of tumours. Lobular carcinomas showed abnormal beta-catenin expression more frequently (77%) than ductal carcinomas (64%) with 46% of lobular cases showing complete absence of beta-catenin immunoreactivity. Cytoplasmic beta-catenin localization was seen only in ductal carcinomas. Aberrant beta-catenin expression was observed in 54% of ductal carcinomas in situ with highly concordant beta-catenin expression patterns in the nearby in situ and invasive components.

CONCLUSIONS

Quantitative and qualitative changes in beta-catenin expression occur in a considerable proportion of in situ and invasive ductal carcinomas and are more prominent in invasive lobular carcinomas.

Expression of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex correlates with the macroscopic appearance of early gastric cancer

E-cadherin and its associated cytoplasmic proteins, alpha-, beta-, and gamma-catenins, play an essential role in the control of epithelial differentiation. We have previously shown that loss or down-regulation of E-cadherin/catenin correlates with poor survival in advanced gastric adenocarcinoma. The aim of this study was to assess the expression of E-cadherin and catenins in early gastric cancers (EGCs). Immunohistochemical staining for E-cadherin and alpha-, beta-, and gamma-catenins was performed on 41 paraffin-embedded gastrectomy specimens of EGC using an indirect immunoperoxidase technique. The pattern of expression and cellular localization of the E-cadherin/catenin complex in tumour cells were correlated with the macroscopic appearance of the tumour according to the Japanese Endoscopic Society classification. The tumours were classified as follows: three type I (protruding) and 38 type II (superficial), of which ten were type IIa (elevated), one was type IIb (flat), and 27 were type IIc (depressed). E-cadherin and alpha-, beta-, and gamma-catenins were expressed at the cell-cell junctions in normal mucosa. Forty out of 41 tumours showed abnormal expression (loss of membranous immunoreactivity and/or nuclear staining) of at least one component of the E-cadherin catenin complex. Loss of E-cadherin immunoreactivity was more frequently seen in type IIb (1/1, 100%) and type IIc (27/27, 100%) than in type I (1/3, 33%) and type IIa (1/10, 10%) (p<0.01). Abnormal expression of E-cadherin and alpha-catenin was more frequently seen in diffuse-type than in intestinal type tumours (p<0.05). Abnormal immunoreactivity of beta- and gamma-catenin, including nuclear localization, was observed in 34% and 7.3% of tumours, respectively, but there was no significant correlation with tumour type or endoscopic appearance. In conclusion, abnormal expression of the E-cadherin/catenin complex occurs in EGC and seems to correlate with macroscopic appearances.

Epithelial mucin expression in bladder cancer: correlation with pathological and clinical parameters

Recently, attention has been drawn to the role of polymorphic epithelial mucin (PEM) as a possible target for cancer immunotherapy. To investigate the expression of this molecule in bladder tissue, we used two mouse monoclonal antibodies (HMFGI and HMFG2) raised against the core protein of the PEM. The localization of these two anti-PEM antibodies was examined in normal (n = 10), inflammatory (n = 10) and malignant (n = 67) bladder tissue samples with the use of a three-step avidin-biotin method. For HMFG1 and HMFG2 localization was successful in 78% and 60% of the bladder cancer samples, respectively, where as they were localized only in 30% and 40% of normal bladder tissue samples, respectively. Staining of either antibodies did not correlate with the grade, stage, or survival of bladder cancer patients. We conclude that PEM is frequently overexpressed by bladder cancer cells and HMFG1 is the antibody of choice to be used as a carrier of a cytotoxic agent for application of intravesical targeted therapy of bladder cancer.

E-cadherin-catenin cell-cell adhesion complex and human cancer

BACKGROUND

The E-cadherin-catenin complex plays a crucial role in epithelial cell-cell adhesion and in the maintenance of tissue architecture. Perturbation in the expression or function of this complex results in loss of intercellular adhesion, with possible consequent cell transformation and tumour progression. Recently, much progress has been made in understanding the interaction between the different components of this protein complex and how this cell-cell adhesion complex is modulated in cancer cells.

METHODS

This is an update of the role of the E-cadherin-catenin complex in human cancers. It emphasizes new features and the possible role of the complex in clinical practice, discussed in the light of 165 references obtained from the Medline database from 1995 to 1999.

RESULTS

More evidence is now appearing to suggest that disturbance in protein-protein interaction in the E-cadherin-catenin adhesion complex is one of the main events in the early and late steps of cancer development. An inverse correlation is found between expression of the E-cadherin-catenin complex and the invasive behaviour of tumour cells. Therefore, E-cadherin-catenin may become a significant prognostic marker for tumour behaviour. Besides its role in establishing tight cell-cell adhesion, beta- catenin plays a major role in cell signalling and promotion of neoplastic growth. This suggests its dual role as a tumour suppressor and as an oncogene in human cancers.

CONCLUSION

Recent developments show that the E-cadherin-catenin complex is more than a 'sticky molecular complex'. Further studies may yield greater insight into the early molecular interactions critical to the initiation and progression of tumours. This should aid the development of novel strategies for both prevention and treatment of cancer.

Microsatellite instability and allelic imbalance in primary and secondary colorectal cancer

BACKGROUND

Several studies of colorectal cancer have shown an association between the number and type of genomic defects and the stage of disease. A subset of colorectal tumours are due to inactivation of DNA mismatch repair genes and these tumours exhibit microsatellite instability. The aim of the present study was to compare and contrast the genomic defects present in both the primary and metastatic stages of the disease using microsatellite probes.

METHODS

Modifications of the allelic profiles of 25 microsatellite regions were studied in a total of 85 colorectal tumours using fluorescent polymerase chain reaction (PCR) technology and subsequent direct analysis on an automatic sequencer. This approach was used because it allows the study of microsatellite instability and allelic imbalance. Stepwise logistic regression analysis was used to develop a model to predict whether the tumour was primary or secondary from the percentage of allelic imbalance. Subsequently, a group of 17 patients with primary colorectal tumours was analysed prospectively to test the proposed model.

RESULTS

Six of 39 primary tumours showed microsatellite instability compared to 0 of 29 liver metastases (P = 0.03). Primary tumours showed significantly less allelic imbalance than liver metastases (P < 0.001). Three probes (d18s53, d9s158 and d10s191) were selected for use in a model to classify a tumour as primary or secondary on the basis of the degree of allelic imbalance. When tested prospectively this model had a specificity of 82%.

CONCLUSIONS

The present study demonstrates the potential importance of using microsatellite probes both as a diagnostic tool and as a research technique to investigate the mechanisms of tumour progression. An important clinical finding is that none of the colorectal liver metastases showed microsatellite instability (0 of 29). This analysis also confirmed other work that has shown a direct relationship between the degree of allelic imbalance and the stage of disease.

Systemic effect of peanut agglutinin following intravenous infusion into rats

BACKGROUND

Ingested peanut agglutinin stimulates colonic proliferation in humans. In rats, ingested peanut agglutinin stimulates hormone release and proliferation in the small and large intestines. Peanut agglutinin is absorbed into the circulation but little is known about the systemic effect of this lectin. Therefore, we studied the effect of intravenous peanut agglutinin on hormone release and intestinal growth.

METHOD

Six rats per group received peanut agglutinin infusion at 0, 2, 20 or 200 microg/rat/day for 6 days via the right jugular vein. Organ weights were measured, pancreatic enzymes, DNA, RNA and protein levels were analysed. Plasma hormones were measured by radioimmunoassay. All tissues were examined histologically. Small intestinal and colonic proliferation rates were estimated by metaphase arrest.

RESULTS

High-dose peanut agglutinin significantly reduced the wet weight of the stomach by 7% (P < 0.05) and large intestine by 10% (P < 0.05). Peanut agglutinin dose-dependently released enteroglucagon; low-, medium- and high-dose by 64%, 126% (P < 0.01) and 180% (P < 0.01), respectively, and glucagon-like peptide-1 by 127% (P < 0.01), 169% (P < 0.01) and 315% (P < 0.001), respectively. Peanut agglutinin had no effect on cholesystokinin, gastrin or insulin levels. Peanut agglutinin, low-, medium- and high-dose stimulated proliferation in the mid colon by 42% (P < 0.01), 30% and 38%, respectively. Only high-dose peanut agglutinin stimulated proliferation in the distal colon by 54% (P < 0.01). No histological changes were evident in any tissue.

CONCLUSION

Intravenous peanut agglutinin released hormones and stimulated colonic proliferation. Proliferation of the small intestine seen after ingestion of peanut agglutinin in previous studies appears to require luminal contact between enterocytes and the lectin. Possible clinical applications include reversal of atrophy during total parenteral nutrition, anastomotic healing after surgery and restoration of mucosa integrity in colitis.

Up-regulated cytoplasmic expression, with reduced membranous distribution, of the src substrate p120(ctn) in gastric carcinoma

p120(ctn) is a substrate of the tyrosine kinase pp60 src. Tyrosine kinases such as src localize to the adherens junctions and phosphorylate junctional proteins in both normal and transformed cells.(1) p120(ctn) forms a complex with E-cadherin at the adherens junction and is phosphorylated by ligands such as epidermal growth factor receptor as well as pp60 src. Phosphorylation of p120(ctn) has been shown to correlate with cell transformation. The aim of this study was to investigate in vivo expression of p120(ctn) in gastric carcinoma and to examine any relationship to pathological characteristics and patient survival. Immunohistochemical staining for p120(ctn) was performed in 68 gastric carcinoma specimens (19 diffuse, 49 intestinal type), in 22 lymph node metastases, and in gastric mucosal biopsies from 16 patients with gastric dysplasia and ten healthy controls. Up-regulation of p120(ctn) cytoplasmic staining was seen in six (37 per cent) of the gastric dysplasia cases and in 45 (66 per cent) tumours (89 per cent of diffuse and 57 per cent of intestinal tumours). Loss of membranous distribution of staining for p120(ctn) was seen in 22 (32 per cent) tumours (52 per cent of diffuse and 24 per cent of intestinal tumours). The staining pattern in the primary tumour showed no correlation with tumour type, grade, or stage, or patient survival. Of 22 lymph node metastases examined, 13 (60 per cent) showed loss of membranous staining. In conclusion, staining for p120(ctn) in gastric carcinoma and dysplasia revealed marked up-regulation of cytoplasmic staining, sometimes associated with reduced membranous expression. Up-regulation of expression of p120(ctn) has not previously been described in human epithelial malignancy. The significance of these findings is uncertain, but they may reflect a change in tyrosine kinase signal transduction pathways, and a role for p120(ctn) in ligand-induced mitogenic signalling and cell transformation.

Source of oncofetal ED-B-containing fibronectin: implications of production by both tumor and endothelial cells

ED-B fibronectin (FN) is a FN isoform derived from alternative splicing of the primary transcript of a single gene. Its expression on tumor stroma and neoformed tumor vasculature and its absence, with few exceptions, in normal adult tissues imply a prognostic and diagnostic value for ED-B FN. We investigated the location and source of ED-B FN because this will be of importance both in understanding its role in tumor development and in designing strategies to target this molecule. We have confirmed that ED-B FN is expressed in the majority of breast and colorectal carcinoma tissue samples, with strong immunohistochemical staining around the tumor cells and in the tumor stroma. No staining of tumor neovasculature was seen. ED-B FN is produced by a range of tumor and endothelial (both primary and transformed) cell lines, as detected by reverse transcription-PCR, but is not expressed at the plasma membrane. Strong expression of human ED-B FN is seen in tumor xenografts. These data indicate that neoplastic cells can act as the source of ED-B FN in tumors. The lack of cell surface expression on tumor cell lines has clear implications for the design of therapeutic strategies which target this molecule.

Catenins and their associated proteins in colorectal cancer

Colorectal cancer is the second most common cause of cancer mortality in the western world. Colorectal cancer has been well studied, and the genetic steps involved in the adenoma to carcinoma sequence have been well elucidated. The first genetic alteration, found in 85% of adenomas, are mutations in the adenomatous polyposis coli (APC) gene. However, the consequences of this and the exact function of APC in the colon is not fully understood. It has been suggested that APC could function through its regulation of beta-catenin, an ubiquitous cytoskeletal protein with multiple binding specificities resulting in diverse functions including cell growth, adhesion, and migration. Any change in these associations may play a role in colorectal cancer development and progression.

Abnormal expression of the E-cadherin-catenin complex in dysplastic Barrett's oesophagus

It is now accepted that altered E-cadherin-catenin complex expression in oesophageal cancer correlates with clinical and pathological parameters, while abnormal E-cadherin expression occurs early in Barrett's oesophagus. We evaluated immunohistochemically the expression and cellular localization of alpha-, beta-, and gamma-catenin, and E-cadherin in 5 dysplastic and 26 non-dysplastic cases of Barrett's oesophagus. Usually all three catenins were localized at the cell membrane, as was E-cadherin. A similar staining pattern for E-cadherin and the catenins was observed in all cases of non-dysplastic Barrett's syndrome. However, 60% (3/5) of cases with dysplasia showed loss of membranous beta-catenin staining and diffuse cytoplasmic distribution, with predominantly nuclear localization in two cases. Membranous staining and concomitant cytoplasmic localization of E-cadherin, alpha-catenin and gamma-catenin were seen in one case with abnormal beta-catenin immunoreactivity. Our results indicate that altered subcellular distribution of beta-catenin occurs frequently in dysplastic Barrett's oesophagus and possibly reflects the signalling function of this molecule.