Nestin expression in cortical dysplasia

Nestin Expression as a Diagnostic and Prognostic Marker in Colorectal Cancer and Other Tumors

Lung cancer, colon cancer, breast cancer, and prostate cancer are the leading causes of death in developed countries. Many cancers display non-specific signs in the early stage of the disease, thus making early diagnosis often difficult. We focused on nestin as a new biomarker of possible clinical importance in the early diagnosis and monitoring of cancer. The expression of nestin takes place at an early stage of neural differentiation, but no expression of the nestin gene can be revealed in normal, mature adult tissues. Nestin plays an important role in the development of the central nervous system and contributes to the organization and maintenance of cell shape. Nestin was found to be a marker of microvessel density, which in turn has proven to be a reliable prognostic factor for neoplastic malignancies in patients. Nestin expression correlates with an increased aggressiveness of tumor cells. The role of nestin in cancers of the colon and rectum, liver, central nervous system, lung cancer, breast cancer, melanoma, and other cancers has been reviewed in the literature. Associations between nestin expression and prognosis or drug-resistance may help in disease management. More research is needed to understand the molecular mechanisms of nestin expression and its role in possible targeted therapy.

Expression of nestin by neural cells in the adult rat and human brain

Neurons and glial cells in the developing brain arise from neural progenitor cells (NPCs). Nestin, an intermediate filament protein, is thought to be expressed exclusively by NPCs in the normal brain, and is replaced by the expression of proteins specific for neurons or glia in differentiated cells. Nestin expressing NPCs are found in the adult brain in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus. While significant attention has been paid to studying NPCs in the SVZ and SGZ in the adult brain, relatively little attention has been paid to determining whether nestin-expressing neural cells (NECs) exist outside of the SVZ and SGZ. We therefore stained sections immunocytochemically from the adult rat and human brain for NECs, observed four distinct classes of these cells, and present here the first comprehensive report on these cells. Class I cells are among the smallest neural cells in the brain and are widely distributed. Class II cells are located in the walls of the aqueduct and third ventricle. Class IV cells are found throughout the forebrain and typically reside immediately adjacent to a neuron. Class III cells are observed only in the basal forebrain and closely related areas such as the hippocampus and corpus striatum. Class III cells resemble neurons structurally and co-express markers associated exclusively with neurons. Cell proliferation experiments demonstrate that Class III cells are not recently born. Instead, these cells appear to be mature neurons in the adult brain that express nestin. Neurons that express nestin are not supposed to exist in the brain at any stage of development. That these unique neurons are found only in brain regions involved in higher order cognitive function suggests that they may be remodeling their cytoskeleton in supporting the neural plasticity required for these functions.

Pinealectomy stimulates and exogenous melatonin inhibits harmful effects of epileptiform activity during pregnancy in the hippocampus of newborn rats: an immunohistochemical study

OBJECTIVES

Epilepsy during the pregnancy is an important problem in clinical practice for newborn individuals. Recently, it has been demonstrated that mothers' epileptic seizures have some harmful effects on newborns, but present data concerning the effects of epileptic phenomena in pregnant mothers on newborn pups are still limited. The current study was undertaken to investigate the morphological changes in the hippocampus of newborn pups of pinealectomized rats subjected to experimental epilepsy during pregnancy.

METHODS

In this study, rats were randomly divided into four groups (ten animals each): intact control group, epilepsy control group, surgical pinealectomy + epilepsy group, and group with melatonin treatment following pinealectomy procedure. The animals in surgical pinealectomy + epilepsy and melatonin treatment groups underwent a surgical intervention consisting of pineal gland removal. At 1 month after surgical pinealectomy, an acute grand mal epileptic seizure was induced by 400 IU penicillin G administration into their hippocampal CA3 region on the 13th day of their pregnancy in all animals except the intact control animals. On the first neonatal day, the hippocampi were removed and processed for microscopic examination. Nestin expression was analysed in the developing hippocampal tissue.

RESULTS

Normal migration and hippocampal maturation were determined in the postnatal rat hippocampus in intact control group, but the morphological structure of the hippocampus in the epilepsy control group corresponded to the early embryonal period. It was found that experimental epilepsy and pinealectomy enhanced nestin immunoreactivity, whereas exogenous melatonin treatment (30 mug/100 g body weight, intraperitoneal) inhibited pinealectomy-stimulated nestin expression in CA1 region of the hippocampus.

CONCLUSION

These findings suggest that epileptic seizures during pregnancy may cause an impaired hippocampal neurogenesis and neuronal maturation in the newborn, and the negative effects in the postnatal rat hippocampus are more dramatic after pinealectomy of the mother; conversely, melatonin administration suppresses these negative changes. This is the first report investigating the effects of maternal epilepsy during pregnancy in pinealectomized rats on nestin immunoexpression in the newborn rat hippocampus.

Immunohistochemical expression of nestin in the non-tumorous hypophysis and in pituitary neoplasms

The aim of the present work was to investigate whether nestin, a member of the intermediate filament family, is immunohistochemically expressed in the non-tumoral human hypophysis and pituitary neoplasms. Twenty-three normal pituitaries and 125 pituitary neoplasms were included. The tissues were formalin-fixed and paraffin embedded. The neoplasms were identified on hematoxylin-eosin stained sections and were classified by immunohistochemistry as well as electron microscopy. For immunohistochemistry, the streptavidin-biotin-peroxidase complex method was applied using appropriate controls. Several corticotrophs in the autopsy obtained pituitaries showed cytoplasmic nestin immunopositivity. No nestin immunoreactivity was found in other cell types in non-tumorous adenohypophyses and in the cells of various pituitary adenomas. Nestin was, however, expressed in a small proportion of endothelial cells in both anterior and posterior lobes. Staining was also noted in several pituicytes, neurohypophysial nerve fibers, and Herring bodies. In contrast to CD-34 and Factor-8 immunostaining which demonstrated immunopositivity in practically all endothelial cells of every capillary, nestin expression was only focally seen suggesting that the functional status of the immunoreactive and non-staining endothelial cells was not the same. No statistically significant correlation was apparent between nestin immunoreactivity and patient age, gender, tumor size, mitotic index, Ki-67, labeling nuclear index, hormonal immunoprofile, and tumor type. In conclusion, nestin expression in adenomas cannot be viewed as a biologically relevant marker of cell proliferation and as a prognostic indicator. The patchy expression of nestin in endothelial cells remains unexplained and its significance requires further studies.

Expression of neural stem cell surface marker CD133 in balloon cells of human focal cortical dysplasia

PURPOSE

Focal cortical dysplasia (CD) is characterized by the presence of dysmorphic neurons, laminar and columnar disorganization. A few patients with CD have balloon cells intermixed with dysmorphic neurons. The cellular characteristics of balloon cells remain unknown. This study was intended to determine further the cellular characteristics of balloon cells.

METHODS

Neocortical tissue resected from five patients with medically intractable focal epilepsy due to CD was studied. The presence of balloon cells (large opalescent cells with eccentric nuclei) was confirmed in all five patients by using cresylecht violet staining. Immunocytochemistry used antibodies against markers of pluripotential stem cells (CD133), multipotential progenitor cells (nestin), antiapoptotic gene products (Bcl-2), immature neurons (beta-tubulin 3, TUJ1), immature glia (vimentin), mature neurons (MAP2 and NeuN), and astrocytes (glial fibrillary acidic protein; GFAP).

RESULTS

Balloon cells (BCs) were found to be immunoreactive to Bcl-2 (46%), vimentin (41%), Nestin (28%), CD133 (28%), MAP2 (27%), GFAP (14%), and TUJ1 (10%). An extremely small number of BCs were immunopositive for NeuN. Confocal double labeling showed that balloon cells were dually immunopositive for CD133/nestin; CD133/GFAP; CD133/Bcl-2, and nestin/GFAP.

CONCLUSIONS

These results show that balloon cells are heterogeneous cell populations expressing cell-surface markers for pluripotential stem cells and proteins for multipotent progenitors, or immature neurons/glia. The presence of stem cell/progenitor markers in the balloon cells could be due to a persistent postnatal neurogenesis or early embryonic insult that resulted in arrest of proliferation/differentiation at their early stages. Additionally, the coexpression of Bcl-2 in CD133-positive balloon cells suggests that a resistance to programmed cell death may be involved in the pathogenesis of cortical dysplasia.

Up-regulation of neuropoiesis generating glial progenitors that infiltrate rat intracranial glioma

To investigate adult neural stem cell (NSC) biology in relation to glioma, the C6 glioma cell line was tagged with green fluorescent protein (GFP) and inoculated into the brain of adult rats. The in vivo biological response of the brain to glioma was studied using immunohistochemical analysis of the subventricular zone (SVZ), peritumoral areas, and glioma. Nestin immunoreactive cells were found infiltrating glioma, but the distribution of abnormal immunoreactivity was restricted to the dorsal and medial border of the tumor relative to the ipsilateral ventricle. The SVZ was found to be hypertrophic, hypercellular, and up-regulated nestin expression. Furthermore, a dense contiguous population of nestin immunoreactive cells could be found streaming from ipsilateral dorsal tip of the SVZ, tracking along the ventral margin of the corpus callosum, and fanning out to encompass and infiltrate the proximal tumor border. Although most cells were either nestin or glial fibrillary acidic protein (GFAP) immunoreactive in the SVZ and along the ventral margin of the corpus callosum, the number of cells co-expressing both markers increased proportionally as the tumor was approached so that the predominant cell population along the proximal tumor border was GFAP immunoreactive. Finally, we demonstrated that a significant proportion of cells found in areas of abnormal immunoreactivity were proliferating, especially in peritumoral areas. In summary, there is an induction of neuropoietic activity in a rat intracranial glioma model that results in an infiltration and accumulation of abnormal nestin and GFAP expressing cells with proliferative potential along the dorsal and medial border of intracranial C6 glioma.

Aberrant neuronal-glial differentiation in Taylor-type focal cortical dysplasia (type IIA/B)

Focal cortical dysplasia (FCD) type IIA/B (Taylor type) is a malformation of cortical development characterized by laminar disorganization and dysplastic neurons. FCD IIA and FCD IIB denote subtypes in which balloon cells are absent or present, respectively. The etiology of FCD IIA/B is unknown, but previous studies suggest that its pathogenesis may involve aberrant, mixed neuronal-glial differentiation. To investigate whether aberrant differentiation is a consistent phenotype in FCD IIA/B, we studied a panel of neuronal and glial marker antigens in a series of 15 FCD IIB cases, and 2 FCD IIA cases. Double-labeling immunofluorescence and confocal imaging revealed that different combinations of neuronal and glial antigens were co-expressed by individual cells in all cases of FCD IIA/B, but not in control cases of epilepsy due to other causes. Co-expression of neuronal and glial markers was most common in balloon cells, but was also observed in dysplastic neurons. The relative expression of neuronal and glial antigens varied over a broad range. Microtubule-associated protein 1B, an immature neuronal marker, was more frequently co-expressed with glial antigens than were mature neuronal markers, such as neuronal nuclear antigen. Our results indicate that aberrant neuronal-glial differentiation is a consistent and robust phenotype in FCD IIA/B, and support the hypothesis that developmental defects of neuronal and glial fate specification play an important role in its pathogenesis.

Insulin signaling pathways in cortical dysplasia and TSC-tubers: tissue microarray analysis

To evaluate the possible roles of the Akt/PKB-mTOR-p70S6K-S6 and cap-dependent translation (eIF4G) pathways in the pathogenesis of tuberous sclerosis complex (TSC)-associated cortical tubers and focal cortical dysplasia (FCD), we performed qualitative and semiquantitative immunohistochemical evaluation on surgically resected corticectomy specimens to detect phosphorylated molecules as activated downstream targets of the signaling pathways. A tissue microarray paraffin block was constructed from 63 archival specimens of surgically resected TSC tubers, FCDs with balloon cells, cortical dysplasia without balloon cells, and histologically normal-appearing neocortex obtained from cases with Rasmussen encephalitis, cystic-gliotic encephalopathy, and temporal lobe epilepsy. Abnormal neuroglial cells were positive for phospho-S6 and phospho-eIF4G with various staining intensities in FCDs and TSC tubers. Both proteins were much less abundantly expressed in normal-appearing neocortex. Phospho-mTOR expression was observed in neurons in all groups. The expression of phospho-S6 and phospho-eIF4G was associated with dysplastic lesions (p < 0.05), and the cytoplasmic phospho-p70S6K expression was most specific for and abundant in TSC tubers and much less prominent in other groups (p < 0.01). These results suggest that constitutive activation of cytoplasmic p70S6K plays a pivotal role in the pathogenesis of TSC tubers and that FCDs possess a distinct mechanism for activation of S6 and eIF4G.

Gene expression profile analyses of cortical dysplasia by cDNA arrays

Cortical dysplasia (CD) is a well-recognized cause of intractable epilepsy, especially in children and is characterized histologically by derangements in cortical development and organization. The objective of this study was to expand the current knowledge of altered gene expression in CD as a first step towards in the identification of additional genes operative in the evolution of CD. Surgical specimens were obtained from eight patients (4 males and 4 females; age range 2-38 years; mean 15 years) with a pathologic diagnosis of CD. Nondysplastic temporal neocortex was obtained from a 2-year-old boy with intractable epilepsy and medial temporal lobe ganglioglioma. After total RNA isolation from frozen brain tissues, we carried out gene expression profiling using a cDNA expression array. Differences in gene expressions between CD and the nondysplastic neocortex were confirmed by semi-quantitative conventional reverse transcription-PCR. Three genes (recombination activating gene 1 (RAG1), heat shock 60 kDa protein 1 (HSP-60), and transforming growth factor beta1 (TGF beta1)) were found to be up-regulated more than two-fold in CD, whereas four genes (phosphoinositide-3-kinase regulatory subunit polypeptide 1 [p85 alpha] (PI3K), frizzled homolog 2 [Drosophila], Bcl-2/adenovirus E1B 19 kDa interacting protein (NIP3), and glia maturation factor beta (GMF beta)) were down-regulated to less than 50% of their normal levels. Interestingly, the majority of genes showing altered expression were associated with apoptosis. Our study demonstrates diverse changes in gene expression in CD. However, it remains to be shown which of these are causally related to the evolution of CD.

Nestin expression after experimental intracerebral hemorrhage

The current study examines nestin expression after intracerebral hemorrhage (ICH), the role of different blood components in nestin upregulation, and the possibility that low doses of thrombin that induce tolerance to brain injury (thrombin preconditioning) might also induce nestin expression. Adult male Sprague-Dawley rats received an intracaudate injection of either whole blood, thrombin (1 or 5 U) or red blood cells (RBCs). Animals were sacrificed for single and double labeling immunohistochemistry to identify which cells express nestin, and for Western blotting to quantify nestin expression. By immunohistochemistry, nestin immunoreactivity was present in large numbers of astrocytes, surrounding the hematoma from day 3 to 1 week after ICH. After 2 weeks, nestin immunoreactivity was co-localized with a neuronal marker (neuronal specific enolase). By Western blot analysis, nestin was strongly expressed at day 3 (P<0.01) and 1 week (P<0.01), and expression persisted for at least 1 month (P<0.05). Intracerebral injection of thrombin or lysed RBCs resulted in a marked increase in nestin expression. Interestingly, injection of a low dose of thrombin that induces brain tolerance also upregulated nestin. The ICH-induced nestin expression in astrocytes may reflect an early response of these cells to injury, while the delayed expression in neurons might be a part of the adaptative response to injury perhaps leading to recovery of function. Nestin induction by a low dose of thrombin suggests that specific receptor-mediated pathways are involved in inducing nestin expression and that nestin may play a role in thrombin preconditioning.

Characteristics of prolonged afterdischarges in children with malformations of cortical development

We investigated aberrant cortical excitability in malformations of cortical development From subdural electrodes, we recorded afterdischarges lasting > or = 6 seconds in 12 of 13 patients with malformations of cortical development and 6 of 10 pediatric patients with nonmalformations of cortical development and reviewed amperage thresholds, distribution of afterdischarges, and motor responses. In patients with malformation of cortical development, motor response thresholds were high; afterdischarge and motor response thresholds, which essentially overlapped, inversely correlated with age (P < .01); afterdischarge thresholds declined with age; and 8 patients showed afterdischarges in remote sites. In nonmalformation of cortical development, afterdischarge thresholds did not significantly correlate with age; motor response thresholds tended to decline with age; and 2 patients had remote afterdischarges. Adolescent patients with malformations of cortical development had lower afterdischarge thresholds than adolescents with nonmalformation of cortical development (P < .05). From their high afterdischarge (and motor response) thresholds, we concluded that preadolescent patients with malformation of cortical development have less excitable, immature cortices, whereas adolescent patients with malformation of cortical development with low afterdischarge thresholds have hyperexcitable cortices. Remote afterdischarges over focal dysplastic cortex suggest aberrant cortical excitability and neural circuits.

A review of gene expression patterns in the malformed brain

Major advances in the identification of genes expressed in malformation-associated epileptic disorders have been made. Some of these changes reflect the complex gene interactions necessary for proper neurodevelopment, whereas others suggest specific synaptic aberrations that could result in a hyperexcitable, and ultimately, epileptic condition. Here we review reported changes in gene expression associated with a malformed brain, with particular emphasis on how these changes provide clues to seizure genesis.