Laser capture microdissection: methodical aspects and applications with emphasis on immuno-laser capture microdissection

Global Gene Expression Profiling: A Complement to Conventional Histopathologic Analysis of Neoplasia

Transcriptional profiling of entire tumors has yielded considerable insight into the molecular mechanisms of heterogeneous cell populations within different types of neoplasms. The data thus acquired can be further refined by microdissection methods that enable the analyses of subpopulations of neoplastic cells. Separation of the various components of a neoplasm (i.e., stromal cells, inflammatory infiltrates, and blood vessels) has been problematic, primarily because of a paucity of tools for accurate microdissection. The advent of laser capture microdissection combined with powerful tools of linear amplification of RNA and high-throughput microarray-based assays have allowed the transcriptional mapping of intricate and highly complex networks within pure populations of neoplastic cells. With this approach, specific “molecular signatures” can be assigned to tumors of distinct or even similar histomorphology, thereby aiding the desired objective of pattern recognition, tumor classification, and prognostication. This review highlights the potential benefits of global gene expression profiling of tumor cells as a complement to conventional histopathologic analyses.

Semiautomated laser capture microdissection of lung adenocarcinoma cytology samples

OBJECTIVE

In the past decade molecular diagnostics has changed the clinical management of lung adenocarcinoma patients. Molecular diagnostics, however, is largely dependent on the quantity and quality of the tumor DNA that is retrieved from the tissue or cytology samples. Frequently, patients are diagnosed on cytology specimens where the tumor cells are scattered within the cell block, making selecting for tumor enrichment difficult. In the past we have used laser capture microdissection (LCM) to select for pure populations of tumor cells to increase the sensitivity of molecular assays. This study explores several methods for semiautomated computer-guided LCM.

STUDY DESIGN

Hematoxylin and eosin- or TTF-1-immunostained slides from a pleural effusion cell block with metastatic lung adenocarcinoma were used for LCM with either AutoScan or a recently described pattern-matching algorithm, spatially invariant vector quantization (SIVQ), to define morphologic predicates (vectors) to select cells of interest.

RESULTS

We retrieved pure populations of tumor cells using both algorithm-guided LCM approaches with slight variations in cellular retrievals. Both methods were semiautomated, requiring minimum technical supervision.

CONCLUSION

In this study we demonstrate the first semiautomated, computer-guided LCM of a cytology specimen using SIVQ and AutoScan, a first step towards the long-term goal of integrating LCM into the clinical cytology-molecular workflow.

Application of laser microdissection and quantitative PCR to assess the response of esophageal cancer to neoadjuvant chemo-radiotherapy

Tissues are complicated three-dimensional structures, composed of different types of interacting cells. Since the cell population of interest might constitute only a minor fraction of the total tissue volume, the problem of tissue heterogeneity has been a major barrier to the molecular analysis of normal versus diseased tissue. Thus, tissue microdissection represents one of the most promising techniques in molecular pathology offering the link between morphology and genetic analysis since it was established in the early 1970s. These first applications and further developments in the techniques enable preparation of morphologically well described and circumscribed cell populations of either tumor cells or surrounding tissue or even cytology specimens without contamination of unwanted cells. Laser capture microdissection is suitable for the dissection of both paraffin embedded and fresh frozen material. Further applications of the dissected genomic material are isolation of DNA and RNA as described later on followed by PCR or RT-PCR and sequencing.

Expression microdissection adapted to commercial laser dissection instruments

Laser-based microdissection facilitates the isolation of specific cell populations from clinical or animal model tissue specimens for molecular analysis. Expression microdissection (xMD) is a second-generation technology that offers considerable advantages in dissection capabilities; however, until recently the method has not been accessible to investigators. This protocol describes the adaptation of xMD to commonly used laser microdissection instruments and to a commercially available handheld laser device in order to make the technique widely available to the biomedical research community. The method improves dissection speed for many applications by using a targeting probe for cell procurement in place of an operator-based, cell-by-cell selection process. Moreover, xMD can provide improved dissection precision because of the unique characteristics of film activation. The time to complete the protocol is highly dependent on the target cell population and the number of cells needed for subsequent molecular analysis.

Immunoguided microdissection techniques

Over the past 15 years, laser-based microdissection has improved the precision by which scientists can procure cells of interest from a heterogeneous tissue section. However, for studies that require a large amount of material (e.g., proteomics) or for cells that are scattered and difficult to identify by standard histological stains, an immunostain-based, automated approach becomes essential. In this chapter, we discuss the use of immunohistochemistry (IHC) and immunofluorescence (IF) to guide the microdissection process via manual and software-driven auto-dissection methods. Although technical challenges still exist with these innovative approaches, we present here methods and protocols to successfully perform immuno-based microdissection on commercially available laser dissection systems.

Laser capture microdissection of human pancreatic beta-cells and RNA preparation for gene expression profiling

Human beta-cell gene profiling is a powerful tool for understanding beta-cell biology in normal and pathological conditions. The assessment is complicated when isolated islets are studied because of contamination by non-beta-cells and the exposure to the trauma of isolation that causes changes in gene expression. These limitations can be overcome by dissecting the beta-cells from the pancreatic tissue directly using the laser capture microdissection (LCM) technique. LCM allows the sampling of specific cell types from tissue sections. The technique requires morphological criteria or specific stains for targeted cells, and the protocols must preserve the condition of the sought-after macromolecules. We have developed a protocol of rapid tissue dehydration followed by identification of human beta-cells by their intrinsic autofluorescence, which allows laser microdissection for gene-profiling studies.

Development and characterization of a novel method to analyze global gene expression profiles in endothelial cells derived from primary tissues

Homogenous cells separated directly from clinical samples with laser capture microdissection (LCM) contain their original transcript messages, which accurately reflects the physiological and pathological changes of the cell before fixation. Analysis of such samples provides a direct understanding of in vivo physiological and pathological processes. The development of modern large-scale analytical techniques have given us a chance to determine the entire transcript profile of interesting cells. Therefore, LCM and gene expression microarray analysis are becoming common tools across a broad range of disciplines, particularly in the basic and clinical biomedical sciences. However, the combination of these technologies is limited in the study of vascular endothelial cell (VEC) since the precise location and separation of VECs is not easily realized and the requirement for relatively large amount of intact RNA for labeling and hybridization is not easily available. In this report, we describe an approach for tissue fixation and isolation of RNA from laser-captured cells retrieved from frozen sections, which had previously been subjected to immunohistochemistry and subsequently subjected to linear amplification and gene expression microarray analysis. Our results demonstrate that nanogram quantities of total RNA isolated from about 3,000 VECs can be amplified and that the amplified RNA can generate enough signal intensity for GeneChip analysis. analysis.

Analysis of T-cell clonality using laser capture microdissection and high-resolution microcapillary electrophoresis

Identification of clonal lymphocytic populations by polymerase chain reaction may be difficult in cases with scant cellular infiltrates or those with a heterogeneous population of cells. Here, we assessed the diagnostic utility of laser capture microdissection (LCM) and high-resolution microcapillary electrophoresis in the analysis of clonality of small biopsy specimens. Clonality was determined in 24 cases: five reactive tonsils, five reactive lymph nodes, six inflammatory skin lesions, and eight T-cell lymphomas. CD3-positive T lymphocytes were captured by LCM from paraffinized immunohistochemically stained sections. Genomic DNA was analyzed for T-cell receptor-gamma gene rearrangement by polymerase chain reaction followed by high-resolution microcapillary electrophoresis with the DNA 500 LabChip and the Agilent Bioanalyzer. In the reactive specimens, T-cell receptor-gamma polymerase chain reaction revealed monoclonal bands when 10 to 1000 cells were captured. This pattern changed to polyclonal when higher numbers of cells were microdissected (2000 to 10,000 cells). In contrast, lymphoma cells were consistently monoclonal whether low or high numbers were microdissected. Microcapillary electrophoresis coupled with LCM facilitated clonality analysis in equivocal cases. In two of eight lymphoma cases, LCM revealed diagnostic monoclonal bands, whereas routine T-cell receptor-gamma assessment of whole tissue sections with 10% polyacrylamide gel electrophoresis demonstrated only minor clonal bands. We conclude that clonality determined by LCM is cell number-dependent. Biopsy specimens containing low numbers of reactive polyclonal T cells may produce pseudomonoclonal bands and therefore should be interpreted with great caution.

Biomarkers for prostate cancer

Novel biomarkers for prostate cancer (PCa) are currently being assessed for utility in PCa diagnosis. This article aims to provide concise information on the current findings that impact prostate cancer research. Results of enzyme-linked immunosorbent assays (ELISA) for single biomarkers, quantitative polymerase chain reaction (PCR)-based assays for DNA/RNA markers will be reviewed in addition to high-throughput proteomic profiling of PCa specimens. The advantages/disadvantages of tissue, blood, urine or seminal plasma as sources for potential biomarkers are discussed emphasizing the consequences for PCa diagnosis. In summary, the majority of promising marker candidates available today needs further validation. Some of the identified markers have the potential to yield novel prognostic tools for PCa, provide novel insights into its pathophysiology, and contribute to the establishment of novel treatment strategies.

Complementary techniques: laser capture microdissection--increasing specificity of gene expression profiling of cancer specimens

Recent developments in sensitive genome characterization and quantitative gene expression analyses that permit precise molecular genetic fingerprinting of tumoral tissue are having a huge impact on cancer diagnostics. However, the significance of the data obtained with these techniques strictly depends on the composition of the biological sample to be analyzed and is greatly enhanced by including a preprocessing step that allows the researcher to distinguish and isolate selected cell populations from surrounding undesired material. This may represent a remarkable problem: indeed, genomic and proteomic analysis in the context of cancer investigation is susceptible to contamination by nonneoplastic cells, which can mask some tumor-specific alterations. Moreover, the heterogeneity of the tissues of a histological section, in which the cell population of interest may constitute only a small fraction, can represent an insurmountable difficulty for the use of quantitative techniques that absolutely depend on genomic material strictly derived from the cells that require analysis. This is obviously not possible if DNA or RNA is extracted from entire biopsies. In the past, this obstacle was partially overcome by manual dissection from slides with a needle or scalpel; however, this method is feasible only if there is a clear demarcation between the tissue under consideration and its surroundings and moreover, allows only an approximate separation of tissues. The recent development of microdissection systems based on laser technology has largely solved this important problem. Laser microdissection is a powerful tool for the isolation of specific cell populations (or single cells) from stained sections of both formalin-fixed, paraffin-embedded and frozen tissues, from cell cultures and even of a single chromosome within a metaphase cell. Resulting material is suitable for a wide range of downstream assays such LOH (loss of heterozygosity) studies, gene expression analysis at the mRNA level and a variety of proteomic approaches such as 2D gel analysis, reverse phase protein array and SELDI protein profiling. This chapter describes the characteristics of the most widely utilized laser microdissection systems and their current applications.

Identification of a unique epigenetic sub-microenvironment in prostate cancer

The glutathione S-transferase P1 (GSTP1) gene promoter is methylated in tumour cells in more than 90% of prostate carcinomas. Recently, GSTP1 promoter methylation was identified in tumour-associated stromal cells in addition to the tumour epithelium. To define the extent and location of stromal methylation, epigenetic mapping using pyrosequencing quantification of GSTP1 promoter methylation and an anatomical three-dimensional reconstruction of an entire human prostate specimen with cancer were performed. Normal epithelium and stroma, tumour epithelium, and tumour-associated stromal cells were laser capture-microdissected from multiple locations throughout the gland. As expected, the GSTP1 promoter in both normal epithelium and normal stromal cells distant from the tumour was not methylated and the tumour epithelium showed consistently high levels of promoter methylation throughout. However, tumour-associated stromal cells were found to be methylated only in a localized and distinct anatomical sub-field of the tumour, revealing the presence of an epigenetically unique microenvironment within the cancer. Morphologically, the sub-field consisted of typical, non-reactive stroma, representing a genomic alteration in cells that appeared otherwise histologically normal. Similar epigenetic anatomical mapping of a control prostate gland without cancer showed low background methylation levels in all cell types throughout the specimen. These data suggest that stromal cell methylation can occur in a distinct sub-region of prostate cancer and may have implications for understanding tumour biology and clinical intervention.

Altered expression pattern of topoisomerase IIalpha in ovarian tumor epithelial and stromal cells after platinum-based chemotherapy

OBJECTIVE

The aim of this study was to evaluate the expression of topoisomerase IIalpha (TOP2A) in epithelial and stromal cells of ovarian cancer.

METHODS

TOP2A expression was analyzed prospectively in normal and tumor epithelial and adjacent stromal cells using quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) after laser microdissection (n = 38), RNA in situ hybridization (n = 13), and immunohistochemistry (n = 69).

RESULTS

TOP2A mRNA was detected by RNA in situ hybridization in all ovarian cancer samples, with stronger hybridization signals in tumor epithelial cells compared to adjacent stromal cells. The same expression pattern was found by immunohistochemistry (P = .0001). Very interestingly, specific change was found in recurrent ovarian cancer after platinum-based chemotherapy: TOP2A expression decreased in tumor epithelial cells of recurrent ovarian cancer compared to primary ovarian cancer (P = .056), whereas it increased in tumor-adjacent stromal cells in carboplatin-treated recurrent tumors compared to primary ovarian cancer (P = .023).

CONCLUSION

TOP2A mRNA and protein expression in ovarian cancer exhibits specific patterns in tumor epithelial and adjacent stromal cells, which are differentially modulated after platinum-based chemotherapy. These data support the recently discovered importance of the stromal compartment in tumor progression and suggest that tumor stromal cells might be relevant to the development of chemotherapy resistance in ovarian cancer.

Validation of a novel ultra-short immunolabeling method for high-quality mRNA preservation in laser microdissection and real-time reverse transcriptase-polymerase chain reaction

Laser microdissection allows isolation of tiny samples from tissue sections for analysis of gene expression by real-time quantitative polymerase chain reaction (PCR). Although immunohistochemical labeling is often required to identify target structures, it drastically degrades mRNA so that shortened protocols are needed. Here, we present a novel method that allows fluorescence double labeling to be performed in only one incubation of 5 minutes. Fab fragments directly coupled to fluorochromes are linked to primary antibodies before these complexes are applied to sections. We quantified the influences of fixatives, labeling solutions, and incubation time on the mRNA yield and compared our method with previously proposed protocols. While tissue components, ie, vimentin and Ki67 antigen, were sufficiently stained after only 5 minutes of incubation, the new method produced a minute loss of mRNA that did not significantly differ from that of untreated sections. In contrast, incubation times of 15 and 30 minutes reduced the mRNA yield by 99.8 to 99.9%. Furthermore, incubation periods longer than 5 minutes critically affected the ratio between the target and housekeeping genes tested by factors of up to 10.6. In conclusion, the novel method described here reduces mRNA loss and potential ratio shifts to a level that does not significantly differ from that of unlabeled samples.

New insights into the pathophysiology of the small airways in asthma

Airway inflammation and remodeling in asthma occur in the central airways and also in the small airways and in the lung parenchyma. The small airways and the lung parenchyma can produce many Th2 cytokines, chemokines, and mediators involved in initiation and perpetuation of the inflammatory process. The distal lung has been recognized as a predominant site of airflow obstruction in asthmatics. Distal inflammation has been described as more severe than large airway inflammation, and strong evidence of remodeling in the lung periphery is emerging. Recognition of asthma as a disease of the entire respiratory tract has clinical significance, highlighting the need to target the distal lung in any strategy for effective treatment of this disease.

Laser Capture Microdissection of Epithelial Cancers Guided by Antibodies Against Fibroblast Activation Protein and Endosialin

Transcriptional profiling of cancer biopsies is used extensively to identify expression signatures for specific cancer types, diagnostic and prognostic subgroups, and novel molecular targets for therapy. To broaden these applications, several challenges remain. For example, the integrity of RNA extracted even from small tissue samples has to be insured and monitored. Moreover, total tumor RNA may hide the marked histologic heterogeneity of human cancers. A principle approach to this heterogeneity has been provided by laser capture microdissection performed on antibody-stained tissue sections (immuno-LCM; iLCM). In this study, we have established a procedure to assess the quality of RNA obtained from tissue sections, coupled with immunostaining using antibodies to different tumor stromal markers, and subsequent iLCM to selectively capture the cancer stroma compartments. The procedure was applied to 53 frozen specimens of human epithelial cancers. Sections were stained for histopathological evaluation, and RNA was isolated from adjacent serial sections. RNA quality was assessed by the Agilent-Bioanalyzer (Agilent, Palo Alto, CA) and by multiplex RT-PCR. Two thirds of the specimens were found to yield good to excellent RNA quality. For microdissection of the tumor stroma with reactive fibroblasts and tumor blood vessels, a rapid incubation protocol with antibodies against fibroblast activation protein (FAP) and against endosialin was developed to ensure RNA integrity for subsequent iLCM. Using these procedures, RNA from distinct tumor compartments can be isolated, analyzed, amplified, and used for transcription profiling.

Proteomics in prostate cancer

PURPOSE OF REVIEW

State-of-the-art proteomics technologies are currently being assessed for utility in the study of prostatic malignancy. This review aims to provide background information on the current proteomics techniques employed in prostate cancer research, recent reports showing the potential application of proteomics in urological practice, and the future direction of proteomics in prostate cancer research and management.

RECENT FINDINGS

Proteomic profiling of serum as a diagnostic tool and a platform for biomarker discovery in prostate cancer continues to draw favorable attention as well as close scrutiny as technological enhancements and multi-center study results are reported. In-vitro studies on prostate cell lines provide positive proof-of-principle results. The application of proteomics to query prostate tissue specimens yields novel prostate cancer biomarkers requiring further validation. The integration of proteomics with immunology also yields promising findings that may translate into clinically relevant biological assays.

SUMMARY

The study of proteomics is an emerging research field, and current studies continue to display potential future usage in prostate cancer management. Succeeding scientific investigations will probably yield new diagnostic and prognostic tools for prostate cancer, provide insights into its underlying biology, and contribute to the development of novel treatment strategies.

Be more specific! Laser-assisted microdissection of plant cells

Laser-assisted microdissection (LAM) is a powerful tool for isolating specific tissues, cell types and even organelles from sectioned biological specimen in a manner conducive to the extraction of RNA, DNA or protein. LAM, which is an established technique in many areas of biology, has now been successfully adapted for use with plant tissues. Here, we provide an overview of the processes involved in conducting a successful LAM study in plants and review recent developments that have made this technique even more desirable. We also discuss how the technology might be exploited to answer some pertinent questions in plant biology.

Analysis for Localization of Steroid Sulfatase in Human Tissues

Human steroid sulfatase (STS) is an enzyme that hydrolyzes several sulfated steroids, such as estrone sulfate, dehydroepiandrosterone sulfate, and cholesterol sulfate, and results in the production of active substances. STS has been demonstrated in human breast cancer tissues and is considered to be involved in intratumoral estrogen production. It is very important to analyze the cellular distribution of STS with accuracy in human tissues in order to obtain a better understanding of the biological significance of STS. Therefore, this chapter describes several morphological approaches used to study the localization of STS, including immunohistochemistry, mRNA in situ hybridization, and laser capture microdissection/reverse transcription-polymerase chain reaction, in human tissues.

Microdissection Techniques for Molecular Testing in Surgical Pathology

Objective.—To describe the techniques for microdissection of paraffin-embedded and frozen tissue sections for the use in molecular applications.

Data Sources.—Original research papers and review papers and the authors' personal experiences.

Data Synthesis.—Manual and laser-capture microdissection are described in detail, with specific protocols for sample preparation and instructions for performing the microdissection. A section addressing frequently asked questions is also included.

Conclusions.—Microdissection is a technique that is very useful both in the research setting and for clinical molecular testing in paraffin-embedded tissue samples. The available techniques range from simple and inexpensive (manual microdissection) to complex and expensive (laser-capture microdissection). All of the techniques, however, require the user to be familiar with microscopy and histology.

The Influence of Immunohistochemistry on mRNA Recovery from Microdissected Frozen and Formalin-Fixed, Paraffin-Embedded Sections

Laser-assisted microdissection (LAM) is now widely used to obtain specific cell populations from heterogeneous tissues. A major disadvantage of LAM is poor tissue morphology during microscopy, in part because coverslips are not used. Immunohistochemical labeling can improve identification of target cells but may affect the subsequent analysis of the microdissected tissue. We studied the effect of immunohistochemistry (IHC) on mRNA recovery from labeled cells after microdissection from both frozen and formalin-fixed, paraffin-embedded (FFPE) sections, using Melan-A and Ki-67 staining in lymph nodes with metastatic melanoma as a model. We developed rapid protocols for immunostaining in an attempt to limit loss of mRNA during procedures. A sensitive real-time quantitative reverse transcription-PCR was used to measure mRNA. We found a marked decrease in the mRNA yield from 500 microdissected cells from frozen and paraffin sections after immunostaining for both markers. Recovery of mRNA decreased by up to 89%, comparing the immunostained with the routinely stained sections. Interestingly, the ratio between mRNA for the two markers was similar in all stains, indicating that immunostained sections may be used for mRNA analysis. We also investigated the effect of storing membrane-mounted sections for microdissection under different conditions. Slides mounted with paraffin sections could be stored at room temperature for up to 90 days with no significant decrease in mRNA recovery.

Laser capture microdissection and mRNA characterization of mouse airway epithelium: methodological considerations

The use of laser capture microdissection (LCM) to obtain epithelial cells lining the distal airways for gene profiling is described. In the mouse, the distal airways are particularly attractive for LCM as there is very high percentage of a single cell type, Clara cells, lining these airways. It is shown that the RNA from distal airway epithelial cells harvested by LCM is well preserved and that with linear amplification sufficient cRNA for microarray analysis can be attained from small numbers of cells.

Spore morphotypes of Thelohania solenopsae (microsporidia) described microscopically and confirmed by PCR of individual spores microdissected from smears by position ablative laser microbeam microscopy

Development of Thelohania solenopsae, a parasite of the red imported fire ant (Solenopsis invicta), until recently was thought to include formation of two types of spores: unicellular meiospores, maturing inside sporophorous vesicles in sets of eight (octospores); and Nosema-like binuclear free spores. Megaspores, discovered in 2001, develop primarily in alates and are morphologically distinct from the two previously known types of spores. The role of megaspores in the T. solenopsae life cycle, as well as their existence, has been questioned. The current research includes light and electron microscopic descriptions of the three major spore morphotypes characteristic of T. solenopsae development. In addition, individual octospores and megaspores were isolated into groups of 8–20 from methanol-fixed and Calcofluor-stained smears of the infected ants for subsequent PCR analysis by the laser pressure catapulting function of a position ablative laser microbeam microscope, a technique applied for the first time to research of microsporidia. The PCR-amplified SSU rDNA nucleotide sequences from octospores and megaspores were identical. This, along with the consistency with which megaspores are detected in infected ants, demonstrates that megaspores are integral to the life cycle of T. solenopsae.

[Laser microdissection in the molecular oncology of prostate cancer]

Nearly all diseases, including prostate cancer (PCA), occur in mixed tissues with different cell types interconnected by multiple interactions. Laser microdissection permits a separate analysis of specific cell types necessary to understand tumorigenesis. Microdissection can be combined with different molecular methods for analyses at the levels of the genome, the transcriptome or the proteome. With respect to the molecular pathogenesis of PCA, normal glands can be compared to preneoplasias, and these in turn to the carcinoma. Different malignancy grades, as well as intra- and extraprostatic tumor parts, can be specifically analysed and molecular markers of aggressiveness can be identified. The molecular signatures obtained provide the basis for functional studies. New prognostic markers and therapeutic targets can be expected from such approaches in the near future. A far reaching goal is the computer representation of multiple molecular components and their interactions, "E-cell in cyberspace", in which prognostic behaviour and therapeutic responsiveness can be approximately predicted.

A novel gene, GCRG224, is differentially expressed in human gastric mucosa

AIM: To clone genes that may predispose us to human gastric cancer and to analyze it’s expression in gastric tissues.

METHODS: Specimens of paired tumor, paratumor and normal gastric mucosa tissues collected from fifteen patients who suffered from stomach antrum adenocarcinoma were used for analysis. Seven out of the fifteen cases were first studied by fluorescent differential display reverse transcription polymerase chain reaction (DDTR-PCR) analysis. The differentially expressed bands of interest were cloned, analyzed by Northern blot, sequencing and RT-PCR. Through BLAST, the sequencing results were compared with GenBank database for homology analysis. In situ hybridization with DIG-labeled cRNA probes was used to analyze the expression of interesting cDNA bands in paraffin embedded paired normal gastric mucosa and cancer tissues isolated from 30 gastric adenocarcinoma patients.

RESULTS: DDRT-PCR showed that one of the interesting cDNA bands, which was named W2, expressed much higher in all seven tested tumor and paratumor samples than in their normal counterparts, it was sub-cloned into a pGEM-T Easy vector. Two subclones were subsequently obtained. One of the subclone, GCRG224, was studied further. The sequencing result showed that GCRG224 consisted of 1159 base pairs and had one open reading frame (ORF). It located at human chromosome 11q14. No homologue was found in GenBank database with GCRG224-ORF. This nucleotide sequence data were submitted to GenBank with accession No. AF438406. RT-PCR showed that GCRG224 expressed higher in 11/15 gastric cancer tissues than in non-tumor tissues. However, the result of Northern blot analysis showed a higher GCRG224 expression in the non-tumor tissue than in the tumor one. Human multiple tissue Northern blot analysis revealed that GCRG224 also expressed in human normal colon tissue, and peripheral blood leukocyte. In situ hybridization analysis showed that only 5/30 adenocarcinoma, 3/18 dysplasia and 6/18 intestinal metaplasia showed higher GCRG224 expression level than the normal gastric glands. However, GCRG224 was over-expressed predominantly in 26/30 cases of normal mucosal epithelium.

CONCLUSION: A novel gene named GCRG224 was identified from human gastric mucosal tissue. It overexpressed in almost all gastric mucosal epithelium but only a small portion of cancer and precancerous leisions. The role of GCRG224 expression in gastric epithelium needs further study.

Hepatitis C virus biology

Hepatitis C virus infection represents a major problem of public health with around 350 millions of chronically infected individuals worldwide. The frequent evolution towards severe liver disease and cancer are the main features of HCV chronic infection. Antiviral therapies, mainly based on the combination of IFN and ribavirin can only assure a long term eradication of the virus in less than half of treated patients. The mechanisms underlying HCV pathogenesis and persistence in the host are still largely unknown and the efforts made by researchers in the understanding the viral biology have been hampered by the absence of a reliable in vitro and in vivo system reproducing HCV infection. The present review will mainly focus on viral pathogenetic mechanisms based on the interaction of HCV proteins (especially core, NS3 and NS5A) with host cellular signaling transduction pathways regulating cell growth and viability and on the strategies developed by the virus to persist in the host and escape to antiviral therapy. Past and recent data obtained in this field with different experimental approaches will be discussed.

Challenges of single-cell diagnostics: analysis of gene expression

Analysis of single-cell gene expression promises a more precise understanding of human disease pathogenesis and important diagnostic applications. Here, we review the rationale for the study of gene expression at the single-cell level, practical methods to isolate homogeneous or single-cell samples, and current approaches to the analysis of single-cell gene expression. Finally, we highlight applications of laser microdissection-based gene expression analysis to the study of human disease and clinical diagnosis.