Laser capture microdissection

Laser capture microdissection (LCM) under direct microscopic visualization permits rapid one-step procurement of selected human cell populations from a section of complex, heterogeneous tissue. In this technique, a transparent thermoplastic film (ethylene vinyl acetate polymer) is applied to the surface of the tissue section on a standard glass histopathology slide; a carbon dioxide laser pulse then specifically activates the film above the cells of interest. Strong focal adhesion allows selective procurement of the targeted cells. Multiple examples of LCM transfer and tissue analysis, including polymerase chain reaction amplification of DNA and RNA, and enzyme recovery from transferred tissue are demonstrated.

Isolation and characterization of viruses related to the SARS coronavirus from animals in southern China

A novel coronavirus (SCoV) is the etiological agent of severe acute respiratory syndrome (SARS). SCoV-like viruses were isolated from Himalayan palm civets found in a live-animal market in Guangdong, China. Evidence of virus infection was also detected in other animals (including a raccoon dog, Nyctereutes procyonoides) and in humans working at the same market. All the animal isolates retain a 29-nucleotide sequence that is not found in most human isolates. The detection of SCoV-like viruses in small, live wild mammals in a retail market indicates a route of interspecies transmission, although the natural reservoir is not known.

Positional cloning of the gene for multiple endocrine neoplasia-type 1

Multiple endocrine neoplasia-type 1 (MEN1) is an autosomal dominant familial cancer syndrome characterized by tumors in parathyroids, enteropancreatic endocrine tissues, and the anterior pituitary. DNA sequencing from a previously identified minimal interval on chromosome 11q13 identified several candidate genes, one of which contained 12 different frameshift, nonsense, missense, and in-frame deletion mutations in 14 probands from 15 families. The MEN1 gene contains 10 exons and encodes a ubiquitously expressed 2.8-kilobase transcript. The predicted 610-amino acid protein product, termed menin, exhibits no apparent similarities to any previously known proteins. The identification of MEN1 will enable improved understanding of the mechanism of endocrine tumorigenesis and should facilitate early diagnosis.

Germline and somatic mutations in the tyrosine kinase domain of the MET proto-oncogene in papillary renal carcinomas

Hereditary papillary renal carcinoma (HPRC) is a recently recognized form of inherited kidney cancer characterized by a predisposition to develop multiple, bilateral papillary renal tumours. The pattern of inheritance of HPRC is consistent with autosomal dominant transmission with reduced penetrance. HPRC is histologically and genetically distinct from two other causes of inherited renal carcinoma, von Hippel-Lindau disease (VHL) and the chromosome translocation (3;8). Malignant papillary renal carcinomas are characterized by trisomy of chromosomes 7, 16 and 17, and in men, by loss of the Y chromosome. Inherited and sporadic clear cell renal carcinomas are characterized by inactivation of both copies of the VHL gene by mutation, and/or by hypermethylation. We found that the HPRC gene was located at chromosome 7q31.1-34 in a 27-centimorgan (cM) interval between D7S496 and D7S1837. We identified missense mutations located in the tyrosine kinase domain of the MET gene in the germline of affected members of HPRC families and in a subset of sporadic papillary renal carcinomas. Three mutations in the MET gene are located in codons that are homologous to those in c-kit and RET, proto-oncogenes that are targets of naturally-occurring mutations. The results suggest that missense mutations located in the MET proto-oncogene lead to constitutive activation of the MET protein and papillary renal carcinomas.

Germline mutations of the MEN1 gene in familial multiple endocrine neoplasia type 1 and related states

Familial multiple endocrine neoplasia type 1 (FMEN1) is an autosomal dominant trait characterized by tumors of the parathyroids, gastro-intestinal endocrine tissue, anterior pituitary and other tissues. We recently cloned the MEN1 gene and confirmed its identity by finding mutations in FMEN1. We have now extended our mutation analysis to 34 more unrelated FMEN1 probands and to two related states, sporadic MEN1 and familial hyperparathyroidism. There was a high prevalence of heterozygous germline MEN1 mutations in sporadic MEN1 (8/11 cases) and in FMEN1 (47/50 probands). One case of sporadic MEN1 was proven to be a new MEN1 mutation. Eight different mutations were observed more than once in FMEN1. Forty different mutations (32 FMEN1 and eight sporadic MEN1) were distributed across the MEN1 gene. Most predicted loss of function of the encoded menin protein, supporting the prediction that MEN1 is a tumor suppressor gene. No MEN1 germline mutation was found in five probands with familial hyperparathyroidism, suggesting that familial hyperparathyroidism often is caused by mutation in another gene or gene(s).

Somatic mutation of the MEN1 gene in parathyroid tumours

Primary hyperparathyroidism is a common disorder with an annual incidence of approximately 0.5 in 1,000 (ref. 1). In more than 95% of cases, the disease is caused by sporadic parathyroid adenoma or sporadic hyperplasia. Some cases are caused by inherited syndromes, such as multiple endocrine neoplasia type 1 (MEN1; ref. 2). In most cases, the molecular basis of parathyroid neoplasia is unknown. Parathyroid adenomas are usually monoclonal, suggesting that one important step in tumour development is a mutation in a progenitor cell. Approximately 30% of sporadic parathyroid tumours show loss of heterozygosity (LOH) for polymorphic markers on 11q13, the site of the MEN1 tumour suppressor gene. This raises the question of whether such sporadic parathyroid tumours are caused by sequential inactivation of both alleles of the MEN1 gene. We recently cloned the MEN1 gene and identified MEN1 germline mutations in fourteen of fifteen kindreds with familial MEN1 (ref. 10). We have studied parathyroid tumours not associated with MEN1 to determine whether somatic mutations in the MEN1 gene are present. Among 33 tumours we found somatic MEN1 gene mutation in 7, while the corresponding MEN1 germline sequence was normal in each patient. All tumours with MEN1 gene mutation showed LOH on 11q13, making the tumour cells hemi- or homozygous for the mutant allele. Thus, somatic MEN1 gene mutation for the mutant allele. Thus, somatic MEN1 gene mutation contributes to tumorigenesis in a substantial number of parathyroid tumours not associated with the MEN1 syndrome.

Trisomy 7-harbouring non-random duplication of the mutant MET allele in hereditary papillary renal carcinomas

The gene defect for hereditary papillary renal carcinoma (HPRC) has recently been mapped to chromosome 7q, and germline mutations of MET (also known as c-met) at 7q31 have been detected in patients with HPRC (ref. 2). Tumours from these patients commonly show trisomy of chromosome 7 when analysed by cytogenetic studies and comparative genomic hybridization (CGH). However, the relationship between trisomy 7 and MET germline mutations is not clear. We studied 16 renal tumours from two patients with documented germline mutations in exon 16 of MET. Fluorescent in situ hybridization (FISH) analysis showed trisomy 7 in all tumours. To determine whether the chromosome bearing the mutant or wild-type MET gene was duplicated, we performed duplex PCR and phosphoimage densitometry using polymorphic microsatellite markers D7S1801 and D7S1822, which were linked to the disease gene locus, and D1S1646 as an internal control. We determined the parental origin of chromosome alleles by genotyping parental DNA. In all 16 tumours there was an increased signal intensity (2:1 ratio) of the microsatellite allele from the chromosome bearing the mutant MET compared with the allele from the chromosome bearing the wild-type MET. Our study demonstrates a non-random duplication of the chromosome bearing the mutated MET in HPRC and implicates this event in tumorigenesis.

Cognition-activated low-frequency modulation of light absorption in human brain

Animal model studies indicate light-absorption changes of the exposed animal brain in response to visual stimulation. Here we report observations of red-light absorbance changes, attributable to repetitive blood concentration changes in response to stimulation in the human brain frontal region by a cognitive process. These responses are observed as low-frequency recurrence of changes by Fourier transform analysis and are attributed to blood concentration change stimulated by the increased metabolic rate of brain tissue in cognitive function. A simple, portable dual wavelength spectrophotometer was attached noninvasively to the human forehead to measure the low frequency and power spectra of fluctuations of absorbances attributed to variations of brain blood concentration in the frontal region. The responses are associated with brain activity in responses to problem solving of analogies presented visually that require an associative function in the frontal region. The method of subtraction of test -rest Fourier transforms minimizes the arterial pulse frequency contributions and identifies specific frequencies--for example, 0.8, 1.6, 1.8 Hz in 24 of 28 tests of nine individuals (85%). Tests in which no increased brain activity was elicited (rest-rest) showed small differences. It is concluded that low-frequency recurrences of brain activity linked to blood concentration increases can be detected in human subjects with an optical device of potentially for simplified tests of cognitive function in the 0- to 3-Hz region and with modifications for wider band recordings in localized tissue volumes by time-resolved spectroscopy.

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.

Monoclonal origin of multicentric Kaposi's sarcoma lesions

BACKGROUND

Kaposi's sarcoma has features of both hyperplastic proliferation and neoplastic growth. Multiple lesions, in which spindle cells are prominent, often arise synchronously over widely dispersed areas. We tested the hypothesis that the spindle cells in these multicentric lesions originate from a single clone of precursor cells.

METHODS

To determine whether Kaposi's sarcoma is a monoclonal disorder, we assessed the methylation patterns of the androgen-receptor gene (HUMARA) in multiple lesions from women with the acquired immunodeficiency syndrome. In polyclonal tissues, about half the copies of each HUMARA allele are methylated, whereas in cells derived from a single clone all the copies of only one allele are methylated. To minimize contamination by normal DNA, we used microdissection to isolate areas composed primarily of spindle cells, the putative tumor cells.

RESULTS

Eight patients with a total of 32 tumors were studied. Of these tumors, 28 had highly unbalanced methylation patterns (i.e., predominant methylation of one HUMARA allele). In all the tumors that had unbalanced methylation from a given patient, the same allele predominated.

CONCLUSIONS

These data indicate that Kaposi's sarcoma is a disseminated monoclonal cancer and that the changes that permit the clonal outgrowth of spindle cells occur before the disease spreads.

Induction of M2 Macrophages Prevents Bone Loss in Murine Periodontitis Models

Periodontitis is characterized by the progressive destruction of tooth-supporting alveolar bone, which is mainly caused by chronic inflammation in response to persistent bacterial insult. It has recently become clear that the pathogenesis of periodontitis is associated with a high ratio of proinflammatory M1 (classically activated) macrophages to anti-inflammatory M2 (alternatively activated). To decrease the inflammatory activity, we locally delivered the C-C motif chemokine ligand 2 (CCL2) using controlled-release microparticles (MPs). CCL2 is known to promote chemotaxis of M0 or M2 phenotype macrophages to the inflamed site and induce M2 phenotype polarization locally. Our in vitro data showed that CCL2 increased the number of M2 phenotype macrophages, decreased TNF-α secretion, and enhanced chemotaxis of RAW264.7 cells toward CCL2 MPs. Moreover, we induced periodontal disease in 2 animal models through inoculation of Porphyromonas gingivalis and ligature around the murine molar. Micro-computed tomography analysis showed significant reduction of alveolar bone loss in the CCL2 MP treatment group when compared with a blank MP group and a no-treatment periodontitis group in both models. Immunohistologic analysis showed a significant increase in the M2 phenotype subset and a decrease in the M1 phenotype subset in the CCL2 MP group of the P. gingivalis-induced model. Also, in both models, tartrate-resistant acidic phosphatase staining showed significantly fewer numbers of osteoclasts in the CCL2 MP group in alveolar bone area. Moreover, quantitative polymerase chain reaction results showed a significant increase in IL-1RA (interleukin 1 receptor antagonist) mRNA expression and a decrease in RANKL (receptor activator of nuclear factor kappa-Β ligand) mRNA expression in the CCL2 MP group in the ligature model. In summary, manipulation of endogenous M2 phenotype macrophages with CCL2 MPs decreased the M1 phenotype:M2 phenotype ratio and prevented alveolar bone loss in mouse periodontitis models. The delivery of CCL2 MPs provides a novel approach to treat periodontal disease.

SiO2 nanoparticles induce cytotoxicity and protein expression alteration in HaCaT cells

Background

Nanometer silicon dioxide (nano-SiO₂) has a wide variety of applications in material sciences, engineering and medicine; however, the potential cell biological and proteomic effects of nano-SiO₂ exposure and the toxic mechanisms remain far from clear.

Results

Here, we evaluated the effects of amorphous nano-SiO₂ (15-nm, 30-nm SiO₂). on cellular viability, cell cycle, apoptosis and protein expression in HaCaT cells by using biochemical and morphological analysis, two-dimensional differential gel electrophoresis (2D-DIGE) as well as mass spectrometry (MS). We found that the cellular viability of HaCaT cells was significantly decreased in a dose-dependent manner after the treatment of nano-SiO₂ and micro-sized SiO₂ particles. The IC₅₀ value (50% concentration of inhibition) was associated with the size of SiO₂ particles. Exposure to nano-SiO₂ and micro-sized SiO₂ particles also induced apoptosis in HaCaT cells in a dose-dependent manner. Furthermore, the smaller SiO₂ particle size was, the higher apoptotic rate the cells underwent. The proteomic analysis revealed that 16 differentially expressed proteins were induced by SiO₂ exposure, and that the expression levels of the differentially expressed proteins were associated with the particle size. The 16 proteins were identified by MALDI-TOF-TOF-MS analysis and could be classified into 5 categories according to their functions. They include oxidative stress-associated proteins; cytoskeleton-associated proteins; molecular chaperones; energy metabolism-associated proteins; apoptosis and tumor-associated proteins.

Conclusions

These results showed that nano-SiO₂ exposure exerted toxic effects and altered protein expression in HaCaT cells. The data indicated the alterations of the proteins, such as the proteins associated with oxidative stress and apoptosis, could be involved in the toxic mechanisms of nano-SiO₂ exposure.

Evidence of independent origin of multiple tumors from patients with prostate cancer

BACKGROUND

In men with prostate cancer, the gland usually contains two or more widely separate tumors. A critical issue of prostatic carcinogenesis is whether these multiple tumors are independent in origin. Molecular analysis of microsatellite (i.e., highly repeated, short nucleotide sequences) alterations in the DNA from separate tumors in the same prostate can be used to determine whether or not these separate tumors arise independently.

METHODS

Four microsatellite polymorphic markers (D8S133, D8S136, and D8S137, for a putative tumor suppressor gene on chromosome 8p, and D17S855, for the BRCA1 gene on chromosome 17q) were used to examine the pattern of allelic loss in prostate cancer from 19 patients who had two or more distantly separate tumors (i.e., located on contralateral sides or separated by at least half the anterior-posterior diameter of the prostate). Forty distantly separate tumors were microdissected, DNA samples were prepared from formalin-fixed, paraffin-embedded wholemount prostate tissue section, and the overall frequencies of loss of heterozygosity at the four loci were determined.

RESULTS

The pattern of allelic loss was compatible with independent tumor origin in 15 of 18 informative cases. A random discordant pattern of allelic deletion was observed in distantly separate tumors, whereas the same allele was consistently lost in cells from different regions of the same tumor. For three patients, the results were compatible with either intraglandular dissemination or independent origin of prostate cancer.

CONCLUSIONS

Our data suggest that multiple tumors in some patients with prostate cancer have independent origin.

Multiple neuroendocrine tumors of the pancreas in von Hippel-Lindau disease patients: histopathological and molecular genetic analysis

Although pancreatic neuroendocrine tumors (NETs) in von Hippel-Lindau (VHL) disease have been reported, their pathological features have not been characterized. In addition, it is unknown whether alterations of the VHL gene are responsible for pancreatic NET development. To evaluate NETs in VHL patients, we performed histopathological analysis of 30 pancreatic tumors in 14 patients. In addition, DNA from NETs and normal pancreatic tissue from 6 patients with documented germ-line VHL gene mutations was studied for allelic deletions of the second copy of the VHL gene by fluorescence in situ hybridization and polymerase chain reaction-based single-strand conformational polymorphism analysis. Morphologically, the tumors were characterized by solid, trabecular, and/or glandular architecture and prominent stromal collagen bands. Sixty percent of the tumors revealed at least focally clear-cell cytology. All tumors were positive for panendocrine immunohistochemistry markers (chromogranin A and/or synaptophysin); 35% of NETs demonstrated focal positivity for pancreatic polypeptide, somatostatin, insulin, and/or glucagon; and no immunostaining for pancreatic and gastrointestinal hormones was observed in 65% of tumors. Dense core neurosecretory granules were evident by electron microscopic examination, and the clear cells additionally revealed abundant intracytoplasmic lipid. All NETs that were subjected to genetic analysis showed allelic loss of the second copy of the VHL gene. We conclude that multiple, nonfunctional pancreatic NETs occur in VHL patients. Stromal collagen bands and clear-cell morphology are important histological features of VHL-associated NETs. The presence of allelic deletions of the VHL gene in pancreatic NETs provides direct molecular evidence for a role of the gene in their tumorigenesis and establishes NET as an independent tumor type of VHL disease.

von Hippel-Lindau gene deletion detected in the stromal cell component of a cerebellar hemangioblastoma associated with von Hippel-Lindau disease

Central nervous system hemangioblastoma is a neoplasm with characteristic and well-described histopathological features, including proliferation of vascular and stromal cells. yet, the histogenesis of the stromal cell component and its neoplastic capacity as compared with the vascular component are still controversial. Stromal cells were selectively procured from formalin-fixed, paraffin-embedded archival tissue from a von Hippel-Lindau (VHL) disease patient with a cerebellar hemangioblastoma and studied for loss of heterozygosity (LOH) of the VHL gene locus and associated microsatellite regions. The stromal cells consistently showed LOH. Analysis of mixed stromal anti vascular areas of this tumor and four other hemangioblastomas of VHL patients showed that loss of heterozygosity was partially obscured. These preliminary results suggest that the stromal component of hemangioblastomas contains genetic alterations consistent with a neoplastic nature. Additional samples of pure stromal cells need to be analyzed to establish the prevalence of VHL gene deletion in stromal cells of capillary hemangioblastoma and, hence, its pathogenetic significance.

Concordance of genetic alterations in poorly differentiated colorectal neuroendocrine carcinomas and associated adenocarcinomas

BACKGROUND

The histopathologic spectrum of colorectal neuroendocrine tumors ranges from benign to highly malignant. In this spectrum, poorly differentiated neuroendocrine carcinoma (PDNC) is the most aggressive type, characterized by early dissemination and a rapidly fatal course. Since it is unclear whether PDNC originates from neoplastic transformation of preexisting neuroectodermal cells, pluripotent epithelial stem cells, or adenocarcinoma precursor cells, we investigated the histogenesis of this type of cancer by performing genetic analyses on a series of colorectal tumors.

METHODS

Archived histologic sections of colorectal PDNC from nine patients were analyzed; gastrointestinal carcinoid tumor specimens from four patients were used as controls. The specimens were deparaffinized, microdissected, and analyzed genetically. After DNA extraction, polymerase chain reaction amplification was performed to investigate alteration (i.e., loss of heterozygosity [LOH]) of the APC (adenomatous polyposis coli), DCC (deleted in colorectal carcinoma), and p53 (also known as TP53) genes.

RESULTS

LOH of the APC, DCC, or p53 genes was observed in six of eight informative PDNC tumors; no LOH was detected in the carcinoid control specimens. Four of five informative PDNC tumors had associated adenocarcinoma; LOH of the APC and p53 genes in these tumors involved the same allele in both tissue components. Four of the five tumors with associated adenocarcinoma showed LOH of the DCC gene; in three of these four tumors, the PDNC and adenomatous components showed LOH of the same allele.

CONCLUSIONS

PDNC and associated adenocarcinoma appear to be derived from the same cell of origin, which is most likely either a pluripotent epithelial stem cell or an adenocarcinoma precursor cell.

Utility of microdissection and polymerase chain reaction for the detection of immunoglobulin gene rearrangement and translocation in primary intraocular lymphoma

OBJECTIVE

Primary intraocular lymphoma, a non-Hodgkin's lymphoma, is a primary central nervous system lymphoma (PCNSL). Diagnosis is usually made by identifying malignant, large B lymphocytes in the vitreous, eye, brain, and cerebral spinal fluid; however, these cells are few, friable, and difficult to recognize. Recently, clonal heavy chain immunoglobulin (IgH) gene rearrangement and bcl-2 gene translocation have been reported in systemic B-cell lymphoma and are used for the detection of malignant cells and in making a diagnosis. The authors investigated the molecular changes in three eyes and a chorioretinal biopsy specimen of four patients with PCNSL.

DESIGN

Human tissue study.

MATERIALS

Five ocular specimens of PCNSL were collected.

INTERVENTION

The first patient had a diagnostic enucleation of the left eye. The second patient underwent diagnostic chorioretinal biopsy. In the third case, a pair of autopsied eyes with reactive lymphoplasmacytic infiltrates of a patient with acquired immune deficiency syndrome (AIDS) were studied. In the fourth case, an enucleated eye of a patient with AIDS-associated lymphoma was sampled.

MAIN OUTCOME MEASURES

The bcl-2 and IgH genes of the lymphoma cells from routine, paraffin-embedded, formaldehyde-fixed, or frozen histologic tissue sections were analyzed using microdissection and polymerase chain reaction (PCR) technique.

RESULTS

Lymphoma cells obtained from the above four cases showed IgH rearrangement gene in the third framework of the VH region. Bcl-2-associated translocation also was detected in three cases (cases 1, 2, and 4).

CONCLUSION

Rearrangement of the IgH gene can serve as a molecular marker for PCNSL. Microdissection allows for procurement and analysis of specific, selected, minute cell populations that are obtained from histologic sections of the complex, heterogeneous tissue. Translocation of IgH and bcl-2, the apoptotic "survival" signal and proto-oncogene, could contribute to the pathogenesis of PCNSL. The combination of microdissection and PCR is a powerful tool for studies of small lesions and cell populations and for understanding disease mechanisms.

VHL gene deletion and enhanced VEGF gene expression detected in the stromal cells of retinal angioma

OBJECTIVE

Retinal angioma frequently occurs in von Hippel-Lindau (VHL) disease. However, VHL gene alterations have not been documented in retinal angiomas.

METHODS

Using tissue microdissection and polymerase chain reaction amplification, we have analyzed 7 retinal angiomas associated with VHL disease for loss of heterozygosity of the VHL gene. In addition, vascular endothelial growth factor expression was evaluated in these tumors by immunohistochemistry and in situ hybridization.

RESULTS

All 6 informative retinal angiomas showed loss of heterozygosity of the VHL gene. Loss of heterozygosity was detected in vacuolated "stromal" cells, but not in vascular cells or reactive glial tissue. Vascular endothelial growth factor protein and messenger RNA were also present in vacuolated "stromal" cells.

CONCLUSIONS

These findings suggest that vacuolated "stromal" cells represent the true neoplastic component in retinal angioma. These cells express vascular endothelial growth factor and therefore may be responsible for abundant neovascularization of retinal angioma.

Molecular cytogenetic fingerprinting of esophageal squamous cell carcinoma by comparative genomic hybridization reveals a consistent pattern of chromosomal alterations

Esophageal cancer is the third most prevalent gastrointestinal malignancy in the world. The tumor responds poorly to various therapeutic regimens and the genetic events underlying esophageal carcinogenesis are not well understood. To identify overall chromosomal aberrations in esophageal squamous cell carcinoma, we performed comparative genomic hybridization (CGH). All 17 tumor samples were found to exhibit multiple gains and losses involving different chromosomal regions. The frequency of chromosomal loss associated with this type of tumor was as follows: in 2q (100%), 3p (100%), 13q (100%), Xq (94%), 4 (82%), 5q (82%), 18q (76%), 9p (76%), 6q (70%), 12q (70%), 14q (65%), 11q (59%), and 1p (53%). Interstitial deletions on 1p, 3p, 5q, 6q, 11q, and 12q were detected also. Chromosomal gains were displayed by chromosomes and chromosome areas: 19 (100%), 20q (94%), 22 (94%), 16p (65%), 17 (59%), 12q (59%), 8q (53%), 9q (53%), and 3q (50%). Two sites showing apparent amplification were 11q (70%) and 5p15 (47%). To validate the CGH data, we isolated a BAC clone mapping to 18q12.1. This clone was used as a probe in interphase fluorescence in situ hybridization of tumor touch preparations and allelic loss was clearly revealed. This study represents the first whole-genome analysis in esophageal squamous cell carcinoma for associated chromosomal aberrations that may be involved in either the genesis or progression of this malignancy.

The multiple endocrine neoplasia type I gene locus is involved in the pathogenesis of type II gastric carcinoids

BACKGROUND & AIMS

Both gastrin and genetic factors were suggested to underlie the pathogenesis of multiple gastric enterochromaffin-like (ECL) cell carcinoids. To assess the role of genetic alterations in carcinoid tumorigenesis, loss of heterozygosity (LOH) at the locus of the multiple endocrine neoplasia type 1 (MEN-1) gene was studied in gastric carcinoids of patients with MEN-1 and chronic atrophic type A gastritis (A-CAG), as well as in sporadically arising intestinal carcinoids.

METHODS

DNA extracted from archival tissue sections of 35 carcinoid tumors was assessed for LOH with eight polymorphic markers on chromosome 11q13. A combined tumor and family study was performed in 1 patient with MEN-1-Zollinger-Ellison syndrome (ZES).

RESULTS

LOH at 11q13 loci was detected in 15 of 20 (75%) MEN-1-ZES carcinoids, and each ECL-cell carcinoid with LOH showed deletion of the wild-type allele. Only 1 of 6 A-CAG carcinoids displayed LOH at the MEN-1 gene locus, and none of the 9 intestinal and rectal carcinoids showed 11q13 LOH.

CONCLUSIONS

Gastric ECL-cell carcinoid is an independent tumor type of MEN-1 that shares a common developmental mechanism (via inactivation of the MEN-1 gene) with enteropancreatic and parathyroid MEN-1 tumors. Further analysis of sporadic and A-CAG carcinoids is needed to elucidate genetic factors involved in their tumorigenesis.

SiO(2) nanoparticles induce global genomic hypomethylation in HaCaT cells

The increasing amount of nanotechnological products, found in our environment and those applicable in engineering, material sciences and medicine has stimulated a growing interest in examining their long-term impact on genetic and epigenetic processes. We examined here the epigenomic response to nm-SiO(2) particles in human HaCaT cells and methyltransferases (DNMTs) and DNA-binding domain proteins (MBDs) induced by nano-SiO(2) particles. Nm-SiO(2) treatment induced global hypoacetylation implying a global epigenomic response. The levels of DNMT1, DNMT3a and methyl-CpG binding protein 2 (MBD2) were also decreased in a dose dependent manner at mRNA and protein level. Epigenetic changes may have long-term effects on gene expression programming long after the initial signal has been removed, and if these changes remain undetected, it could lead to long-term untoward effects in biological systems. These studies suggest that nanoparticles could cause more subtle epigenetic changes which merit thorough examination of environmental nanoparticles and novel candidate nanomaterials for medical applications.

Comparison of genetic alterations in colonic adenoma and ulcerative colitis-associated dysplasia and carcinoma

Carcinoma is an important complication of ulcerative colitis (UC) and develops from dysplastic precursor lesions. Genetic changes involved in the malignant transformation have not been fully characterized. We studied 19 cases of UC with high-grade dysplasia (HGD) and eight samples of associated carcinoma (CA). Microdissection of normal epithelium, epithelium at the site of chronic inflammation, HGD, and CA was performed. Polymerase chain reaction (PCR) amplification for loss of heterozygosity (LOH) of the following polymorphic microsatellites of putative tumor suppressor gene loci was done: APC (5q), DCC (18q), p16 (9p), p53 (17p), and 8p12. To compare genetic alterations, 22 typical adenomas of the colon were studied with the markers for APC and pl6 gene loci. The results indicated that LOH of p16 and p53 were present in nondysplastic epithelium, HGD, and CA. However, the LOH in nondysplastic epithelium was detected in some associated HGD, but not all. Whereas LOH of p16 was present in 7 of 14 cases of HGD (50%), it was noted in only 1 of 22 adenomas (5.0%). LOH in the APC and DCC gene loci in UC was noted in HGD with associated CA, but LOH of APC was not present either in cases of nondysplastic epithelium or in HGD alone. Conversely, LOH in APC was present in 4 of 19 colonic adenomas. We conclude that LOH of p53 and p16 in nondysplastic epithelium may be associated with chronic reparative processes. These changes may lead to susceptibility to further genetic damage involving the APC and DCC gene loci in the development of dysplasia and progression of CA in UC. The low frequency of LOH in the p16 gene (9p) in adenomas compared with dysplasia in UC combined with infrequent LOH in APC gene loci in cases of pure dysplasia in UC may support this combination of markers as a clinical test for the differentiation of polypoid dysplasia from adenomas in UC.

Antibody to H(+) V-ATPase subunit E colocalizes with portasomes in alkaline larval midgut of a freshwater mosquito (Aedes aegypti)

The pH profile, gross structure, ultrastructure and immunolabeling of the mosquito (Aedes aegypti) larval midgut are described as a first step in analyzing the role of plasma membrane H(+)V-ATPase in the alkalization of the gut, nutrient uptake and ionic regulation. Binding of an antibody to H(+)V-ATPase subunit E colocalizes with ‘portasomes’ (approximately 10 nm in diameter), which are thought to correspond to the V(1) part of the H(+) V-ATPase. In gastric caeca (pH 8), both antibody-binding sites and portasomes are located apically; in the anterior midgut (pH 10–11), they are located basally; and in the posterior midgut (pH approximately equal to 8) they are again located apically. The hypothesis that the energization of alkalization is mediated by an H(+) V-ATPase is supported by the inability of larvae to maintain the high pH after 72 h in 10 (micro)M bafilomycin B1. Confirming earlier reports, the two principal epithelial cell types are designated as ‘columnar’ and ‘cuboidal’ cells. The apical plasma membranes (microvilli) of epithelial cells in the gastric caeca and basal infoldings of anterior midgut are invaded by mitochondria that lie within approximately 20 nm of the portasome-studded plasma membranes. The colocalization of V-ATPase-immunolabeling sites and portasomes to specific plasma membranes within so-called ‘mitochondria-rich’ cells of gastric caeca and anterior midgut suggests that midgut alkalization in mosquitoes is achieved by molecular mechanisms similar to those that have been described in caterpillars, even though the gross structure of the midgut and the localization of the V-ATPase are dissimilar in the two species. In caterpillars, the high alkalinity is thought to break down dietary tannins, which block nutrient absorption; it may play a similar role in plant-detritus-feeding mosquito larvae. The colocalization of immunolabeling sites and portasomes, together with the presence of long, ‘absorptive-type’ microvilli in the posterior midgut, suggest that the V-ATPase energizes nutrient uptake there.

Uptake of silica nanoparticles: neurotoxicity and Alzheimer-like pathology in human SK-N-SH and mouse neuro2a neuroblastoma cells

Growing concern has been raised over the potential adverse effects of engineered nanoparticles on human health due to their increasing use in commercial and medical applications. Silica nanoparticles (SiNPs) are one of the most widely used nanoparticles in industry and have been formulated for cellular and non-viral gene delivery in the central nerve system. However, the potential neurotoxicity of SiNPs remains largely unclear. In this study, we investigated the cellular uptake of SiNPs in human SK-N-SH and mouse neuro2a (N2a) neuroblastoma cells treated with 10.0 μg/ml of 15-nm SiNPs for 24 h by transmission electron microscopy. We found that SiNPs were mainly localized in the cytoplasm of the treated cells. The treatment of SiNPs at various concentrations impaired the morphology of SK-N-SH and N2a cells, characterized by increased number of round cells, diminishing of dendrite-like processes and decreased cell density. SiNPs significantly decreased the cell viability, induced cellular apoptosis, and elevated the levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner in both cell lines. Additionally, increased deposit of intracellular β-amyloid 1-42 (Aβ(1-42)) and enhanced phosphorylation of tau at Ser262 and Ser396, two specific pathological hallmarks of Alzheimer's disease (AD), were observed in both cell lines with SiNPs treatment. Concomitantly, the expression of amyloid precursor protein (APP) was up-regulated, while amyloid-β-degrading enzyme neprilysin was down-regulated in SiNP-treated cells. Finally, activity-dependent phosphorylation of glycogen syntheses kinase (GSK)-3β at Ser9 (inactive form) was significantly decreased in SiNP-treated SK-N-SH cells. Taken together, these data demonstrated that exposure to SiNPs induced neurotoxicity and pathological signs of AD. The pre-Alzheimer-like pathology induced by SiNPs might result from the dys-regulated expression of APP/neprilysin and activation of GSK-3β. This is the first study with direct evidence indicating that in addition to neurotoxicity induced by SiNPs, the application of SiNPs might increase the risk of developing AD.