Establishment of human tumor strains from cell lines transplanted into athymic mice and rats

The authors describe human cancer strains established from 6 cell lines transplanted to nude mice and rats: cancer of the liver, colon, lung, bladder and Burkitt's lymphoma. In spite of a long history (for several years) of cell line transfers in vitro, on transplantation of tumor cells, nude animals established tumors histologically identical to the primary cancer.     

Insulin-like growth factor binding protein expression in human small cell lung cancer cell lines

Insulin-like growth factor binding proteins (IGF-BP) are secreted by several human small cell lung cancer cell lines (SCLC). In order to identify the IGF-BPs from SCLC cell lines the RNA from 10 different SCLC cell lines was analyzed by Northern blot analysis with the probes for three different IGF-BPs, IGFBP-1, IGFBP-2, and IGFBP-3. No hybridization signal could be detected with the probes encoding for IGFBP-1 and IGFBP-3. The hybridization with different IGFBP-2-specific oligodeoxynucleotide probes and with the corresponding full-length cDNA showed that all SCLC cell lines which secreted IGF-BPs express IGFBP-2.     

Genetic inheritance of gene expression in human cell lines

Combining genetic inheritance information, for both molecular profiles and complex traits, is a promising strategy not only for detecting quantitative trait loci (QTLs) for complex traits but for understanding which genes, pathways, and biological processes are also under the influence of a given QTL. As a primary step in determining the feasibility of such an approach in humans, we present the largest survey to date, to our knowledge, of the heritability of gene-expression traits in segregating human populations. In particular, we measured expression for 23,499 genes in lymphoblastoid cell lines for members of 15 Centre d'Etude du Polymorphisme Humain (CEPH) families. Of the total set of genes, 2,340 were found to be expressed, of which 31% had significant heritability when a false-discovery rate of 0.05 was used. QTLs were detected for 33 genes on the basis of at least one P value <.000005. Of these, 13 genes possessed a QTL within 5 Mb of their physical location. Hierarchical clustering was performed on the basis of both Pearson correlation of gene expression and genetic correlation. Both reflected biologically relevant activity taking place in the lymphoblastoid cell lines, with greater coherency represented in Kyoto Encyclopedia of Genes and Genomes database (KEGG) pathways than in Gene Ontology database pathways. However, more pathway coherence was observed in KEGG pathways when clustering was based on genetic correlation than when clustering was based on Pearson correlation. As more expression data in segregating populations are generated, viewing clusters or networks based on genetic correlation measures and shared QTLs will offer potentially novel insights into the relationship among genes that may underlie complex traits.     

Factors affecting human cytomegalovirus gene expression in human monocyte cell lines

To understand the mechanisms for establishing and reactivating monocytes and macrophages from latency by human cytomegalovirus (HCMV), human monocyte cell lines were infected and HCMV gene expression was investigated. Indirect immunofluorescence assay (IFA) with monoclonal antibody to HCMV major immediate early (MIE) IE1 or IE2 proteins revealed that HCMV MIE genes were expressed at low levels in relatively more differentiated THP-1 cells with TPA treatment after virus infection (posttreatment). Less differentiated cells such as U937 or HL60 did not support MIE gene expression even after TPA treatment. If THP-1 cells were pretreated before virus infection with TPA and became differentiated at the time of HCMV infection, MIE gene expression increased by 5-6 fold. Therefore, the relative degree of monocyte cell differentiation appears to be an important factor for regulating HCMV gene expression. Further IFA studies using monoclonal antibodies specific for IE1 or IE2 proteins indicate that the sequence and general pattern of IE1 and IE2 gene expression in THP-1 cells treated with TPA were similar to those in permissive human fibroblast cells with some delay in time. Formation of the replication compartment detected with monoclonal antibody to HCMV polymerase accessory protein UL44 in THP-1 cells suggests a fully productive replication process of HCMV in these cells. Monocytes are known to be induced to differentiate by hydrocortisone (HC), tumor necrosis factor (TNF)-alpha or interferon (IFN)-gamma. HC, which is known to stimulate HCMV replication in permissive human fibroblast (HF) cells, enhanced HCMV gene expression by 2-3 fold in TPA-pre or posttreated THP-1 cells, but TNF-alpha or IFN-gamma had little effect. Nitric oxide (NO) is released by immune cells in the defense against foreign stimuli and was shown to inhibit HCMV gene expression in HF cells. Increasing NO by nitroprusside significantly reduced HCMV gene expression in THP-1 cells. Therefore, it appears that the expression of HCMV immediate early genes in THP-1 cells treated with TPA closely resembles those in permissive HF cells.     

Human colonic cancer lines transplanted in athymic mice and rats

A number of human colonic cancer strains from operative specimens transplanted to nude mice and rats are described. Histologic characteristics of the strains completely correspond with those of the primary tumor. The strains contain mainly human cells, which is proved by 5 peaks of lactate dehydrogenase isoenzymes detected at electrophoresis in agar gel.     

Variation of human mucin gene expression in gastric cancer cell lines and gastric mucous cell primary cultures

Human gastric mucous cells - gastric cancer cell lines mucin gene expression - TNFalpha - RT-PCR immunocytochemistry Little is known on the expression pattern of mucin genes in human gastric cancer cell lines in relation to mucin expression in normal gastric epithelial cells. Thus, the aim of this study was to compare gastric cancer cell lines and non-transformed epithelial cells in their expression of the different mucin genes, in order to use these cells as models for physiological MUC expression in human stomach. Human gastric mucous cell primary cultures which were obtained from surgical specimen by collagenase/pronase treatment and a panel of six human gastric cancer cells were screened for mRNA expression of the mucin genes MUC1, MUC2, MUC5AC, MUC5B, and MUC6. Mucin gene expression was analyzed by semi-quantitative RT-PCR, and by Western blotting and immunocytochemistry. Primary cultured human gastric mucous cells retained the stomach-specific pattern of mRNA expression found in gastric mucosal biopsies (MUC1, MUC5AC, MUC6), whereas any gastric cancer cell line exhibited an aberrant mucin gene expression. Mucin gene expression showed large variations in levels and patterns from cell line to cell line, but MUC2 was aberrantly expressed in all cancer cells. Immunocytochemistry confirmed aberrant MUC2 protein expression in cancer cells. The expression of the secretory mucin genes MUC2 and MUC5AC varied in relation to the length of cultivation of the cancer cell lines. Treatment of the gastric cancer cells with TNFalpha resulted in an enhanced mRNA expression of MUC1, MUC2, and MUC5AC (2-fold increase within 3 hours; p <0.05). In contrast, immunocytochemistry disclosed a decrease in MUC2 and MUC5AC staining intensity. Our results indicate that primary cultured human gastric mucous cells provide a physiological in vitro system for investigations of gastric mucin gene regulation. In gastric cancer cells marked changes in the mucin gene expression pattern are found with coexpression of non-gastric type mucins. Gastric mucin gene expression may be regulated by proinflammatory cytokines which could have implications in gastritis.     

Alterations of expression and regulation of transforming growth factor beta in human cancer prostate cell lines

TGFβ can promote and/or suppress prostate tumor growth through multiple and opposing actions. Alterations of its expression, secretion, regulation or of the sensitivity of target cells can lead to a favorable environment for tumor development. To gain a better insight in TGFβ function during cancer progression, we have used different cultured human prostate cells: preneoplastic PNT2 cells, the androgen-dependent LNCaP and the androgen-independent PC3 and DU145 prostate cancer cell lines. We have studied by specific ELISA assays in conditioned media (CM), the secretion of TGFβ1 and TGFβ2 in basal conditions and after hormonal treatment (DHT or E2) and the expression of TGFβ1 mRNA by Northern blot. We have also compared the effect of fibroblast CM on TGFβ secretion by the different cell types. Compared to PNT2 cells, cancer cell lines secrete lower levels of active TGFβ which are not increased in the presence of fibroblast CM. LNCaP cells respond to androgen or estrogen treatment by a 10-fold increase of active TGFβ secretion while PC3 and DU145 are unresponsive. In conclusion, prostate cancer cell lines have lost part of their ability to secrete and activate TGFβ, and to regulate this secretion through stromal–epithelial interactions. Androgen-sensitive cancer cells may compensate this loss by hormonal regulation.     

Real-time expression profiling of microRNA precursors in human cancer cell lines

Our previous study described a real-time PCR method to quantify microRNA (miRNA) precursors using SYBR green detection [T. D. Schmittgen, J. Jiang, Q. Liu and L. Yang (2004) Nucleic Acids Res., 32, e43]. The present study adapted the assay to a 384-well format and expanded it to include primers to 222 human miRNA precursors. TaqMan minor groove binder probes were used to discriminate nearly identical members of the let-7 family of miRNA isoforms. The miRNA precursor expression was profiled in 32 human cell lines from lung, breast, colorectal, hematologic, prostate, pancreatic, and head and neck cancers. Some miRNA precursors were expressed at similar levels in many of the cell lines, while others were differentially expressed. Clustering analysis of the miRNA precursor expression data revealed that most of the cell lines clustered into their respective tissues from which each cell line was ostensibly derived. miRNA precursor expression by PCR paralleled the mature miRNA expression by northern blotting for most of the conditions studied. Our study provides PCR primer sequences to all of the known human miRNA precursors as of December 2004 and provides a database of the miRNA precursor expression in many commonly used human cancer cell lines.     

Correlated gene expression between beta-1,4-galactosyltransferase V and N-acetylglucosaminyltransferase V in human cancer cell lines

Since our previous study showed that the gene expression level of beta-1,4-galactosyltransferase (beta-1,4-GalT) V is only increased in mouse NIH3T3 transformant and that beta-1,4-GalT V preferentially galactosylates the GlcNAcbeta1 --> 6Man branch of oligosaccharides [Shirane et al. (1999) Biochem. Biophys. Res. Commun. 265, 434-438], whether its gene expression is correlated with malignant transformation was investigated. Northern blot analysis of beta-1, 4-GalTs I, II, III, IV, V, and VI and N-acetylglucosaminyltransferase (GlcNAcT)V in human cancer cell lines showed that the gene expression levels of beta-1,4-GalT V but not other beta-1,4-GalTs are strongly correlated with those of GlcNAcT V whose activity was shown to increase by malignant transformation. These results indicate that beta-1,4-GalT V is involved in the galactosylation of highly branched oligosaccharides characteristic of malignantly transformed cells.     

Identification of circadian-related gene expression profiles in entrained breast cancer cell lines

Cancer cells have broken circadian clocks when compared to their normal tissue counterparts. Moreover, it has been shown in breast cancer that disruption of common circadian oscillations is associated with a more negative prognosis. Numerous studies, focused on canonical circadian genes in breast cancer cell lines, have suggested that there are no mRNA circadian-like oscillations. Nevertheless, cancer cell lines have not been extensively characterized and it is unknown to what extent the circadian oscillations are disrupted. We have chosen representative non-cancerous and cancerous breast cell lines (MCF-10A, MCF-7, ZR-75-30, MDA-MB-231 and HCC-1954) in order to determine the degree to which the circadian clock is damaged. We used serum shock to synchronize the circadian clocks in culture. Our aim was to initially observe the time course of gene expression using cDNA microarrays in the non-cancerous MCF-10A and the cancerous MCF-7 cells for screening and then to characterize specific genes in other cell lines. We used a cosine function to select highly correlated profiles. Some of the identified genes were validated by quantitative polymerase chain reaction (qPCR) and further evaluated in the other breast cancer cell lines. Interestingly, we observed that breast cancer and non-cancerous cultured cells are able to generate specific circadian expression profiles in response to the serum shock. The rhythmic genes, suggested via microarray and measured in each particular subtype, suggest that each breast cancer cell type responds differently to the circadian synchronization. Future results could identify circadian-like genes that are altered in breast cancer and non-cancerous cells, which can be used to propose novel treatments. Breast cell lines are potential models for in vitro studies of circadian clocks and clock-controlled pathways.     

Variability of gene expression profiles in human blood and lymphoblastoid cell lines

Background

Infection of plants by pathogens and the subsequent disease development involves substantial changes in the biochemistry and physiology of both partners. Analysis of genes that are expressed during these interactions represents a powerful strategy to obtain insights into the molecular events underlying these changes. We have employed expressed sequence tag (EST) analysis to identify rice genes involved in defense responses against infection by the blast fungus Magnaporthe oryzae and fungal genes involved in infectious growth within the host during a compatible interaction.

Results

A cDNA library was constructed with RNA from rice leaves (Oryza sativa cv. Hwacheong) infected with M. oryzae strain KJ201. To enrich for fungal genes, subtraction library using PCR-based suppression subtractive hybridization was constructed with RNA from infected rice leaves as a tester and that from uninfected rice leaves as the driver. A total of 4,148 clones from two libraries were sequenced to generate 2,302 non-redundant ESTs. Of these, 712 and 1,562 ESTs could be identified to encode fungal and rice genes, respectively. To predict gene function, Gene Ontology (GO) analysis was applied, with 31% and 32% of rice and fungal ESTs being assigned to GO terms, respectively. One hundred uniESTs were found to be specific to fungal infection EST. More than 80 full-length fungal cDNA sequences were used to validate ab initio annotated gene model of M. oryzae genome sequence.

Conclusion

This study shows the power of ESTs to refine genome annotation and functional characterization. Results of this work have advanced our understanding of the molecular mechanisms underpinning fungal-plant interactions and formed the basis for new hypothesis.     

Erythropoietin gene expression in haemopoietic cell lines

Erythropoietin (Epo) gene expression was studied in a number of different haemopoietic cell lines by in situ hybridization and Northern Blot analysis using a radioisotope-labelled monkey Epo DNA probe. A positive message was expressed by a human cell line, CM-S, derived from a patient with congenital hypoplastic anemia, and by a murine erythro-leukaemic cell line, clone 707, derived from the spleen of Friend virus-infected mice. No message was detected in two megakaryoblastic cell lines, and in a monocytic cell line, derived from a patient with acute monocytic leukaemia. These data may fit with the hypothesis of expression of Epo and other growth factors by haemopoietic cells through a mechanism of so-called autocrine secretion.