Aberrant overexpression of 53BP2 mRNA in lung cancer cell lines

The p53-binding protein 2 (53BP2) was identified as a binding protein to a tumor suppressor p53. We examined the genetic aberrations of 53BP2 gene in various human cancer cell lines. Although no gross genomic alteration or mutation of 53BP2 gene was observed, 53BP2 mRNA levels were highly variable. There was no association between the 53BP2 mRNA level and the p53 status. When we examined sensitivities of these cell lines to DNA-damaging agents including UV irradiation, X-ray irradiation and cis-diamine-dichloroplatinum (CDDP), we found that higher 53BP2 mRNA expression was correlated with the sensitivity to these agents.     

Cloning and characterization of Ehox,a novel homeobox gene essential for embryonic stem cell differentiation

We report here the identification and characterization of a novel paired-like homeobox-containing gene (Ehox). This gene, identified in embryonic stem (ES) cells, is differentially expressed during in vitro ES cell differentiation. We have assessed Ehox function using the ES cell in vitro differentiation system. This has involved molecular and biological analyses of the effects of sense or antisense Ehox expression (using episomal vectors) on ES cell differentiation. Analysis of antisense Ehox-expressing ES cells indicates that they are unable to express marker genes associated with hematopoietic, endothelial, or cardiac differentiation following removal of leukemia inhibitory factor. In contrast, overexpression of Ehox using the sense construct accelerated the appearance of these differentiation markers. ES cell self-renewal and differentiation assays reveal that inhibition of Ehox activity results in the maintenance of a stem cell phenotype in limiting concentrations of leukemia inhibitory factor and the almost complete impairment of the cardiomyocyte differentiation capacity of these cells. We therefore conclude that Ehox is a novel homeobox-containing gene that is essential for the earliest stages of murine ES cell differentiation.     

Design of novel tyrosine-nitrogen mustard hybrid molecules active against uterine, ovarian and breast cancer cell lines

L-para-Tyrosine was linked to ortho-hydroxyaniline, meta-hydroxyaniline and para-hydroxyaniline giving three distinct tyrosinamide molecules. The new extended amino acid derivatives were constructed to imitate, in part, the estradiol (E(2), the natural female sex hormone) nucleus. The resulting tyrosinamides were then linked to chlorambucil either directly, or via a 5 and 10 carbon atoms spacer chain. This was done in an attempt to target cancerous cells expressing the estrogen receptor alpha (ERα) and to obtain a more specific chemotherapeutic agent. The tyrosinamide-chlorambucil molecules were designed and synthesized in good yields, according to two different approaches. The novel compounds were evaluated for their anticancer efficacy in hormone-dependent and hormone-independent (ER+; MCF-7 and ER-; MDA-MB-231) breast cancer cell lines. Interestingly, the meta-hydroxyphenyl-tyrosinamide-chlorambucil derivatives were more active than the ortho- and para- analogs. The molecules bearing a 5 carbon atoms spacer were selected for additional biological study using a panel of female cancerous cells; breast (ZR-75-1, MDA-MB-436, MDA-MB-468), ovarian (OVCAR-3, A2780) and uterine (Ishikawa, HEC-1A). It was discovered that for breast cancer cells, the new compounds were up to 4.2 times more active than chlorambucil itself.     

Homeobrain, a novel paired-like homeobox gene is expressed in the Drosophila brain

The homeobrain (hbn) gene is a new paired-like homeobox gene which is expressed in the embryonic brain and the ventral nerve cord. Expression of homeobrain initiates during the blastoderm stage in the anterior dorsal head primordia and the gene is persistently expressed in these cells which form parts of the brain during later embryonic stages. An additional weaker expression pattern is detected in cells of the ventral nerve cord from stage 11 on. The homeodomain in the Homeobrain protein is most similar to the Drosophila proteins DRx, Aristaless and Munster. In addition, the localized brain expression patterns of homeobrain and DRx resemble each other. Two other homeobox genes, orthopedia and DRx are clustered in the 57B region along with homeobrain. The current evidence indicates that homeobrain, DRx and orthopedia form a homeobox gene cluster in which all the members are expressed in specific embryonic brain subregions.     

Msx1 gene overexpression induces G1 phase cell arrest in human ovarian cancer cell line OVCAR3

Recent evidence suggested an involvement of homeobox genes in tumorigenesis. Here we investigated whether one of homeobox-containing genes, Msx1, might be involved in the regulation of cell proliferation and cell cycle using Msx1 overexpressing human ovarian cancer cell line, OVCAR3. Overexpression of Msx1 in OVCAR3 cells inhibited cell proliferation by markedly increasing the length of the G1 phase of the cell cycle over control cells. Consistent with this result, dramatic suppression of cyclins D1, D3, E, cyclin-dependent kinase 4, c-Jun, and Rb was observed. Elevated expression of genes involved in the growth arrest and apoptosis (GADD153 and apoptotic cystein protease MCH4) and suppression of proliferation associated protein gene (PAG) in Msx1-overexpressing cells by cDNA expression array analysis provide further evidence for a potential repressor function of Msx1 in cell cycle progression.     

Immunological profiling of a panel of human ovarian cancer cell lines

Purpose The efficient identification of peptide antigens recognized by ovarian cancer-specific cytotoxic T lymphocytes (CTL) requires the use of well-characterized ovarian cancer cell lines. To develop such a panel of cell lines, 11 ovarian cancer cell lines were characterized for the expression of class I and class II major histocompatibility complex (MHC)-encoded molecules, 15 tumor antigens, and immunosuppressive cytokines [transforming growth factor β (TGF-β) and IL-10]. Methods Class I MHC gene expression was determined by polymerase chain reaction (PCR), and class I and class II MHC protein expression was determined by flow cytometry. Tumor antigen expression was determined by a combination of polymerase chain reaction (PCR) and flow cytometry. Cytokine expression was determined by ELISA. Results Each of the ovarian cancer cell lines expresses cytokeratins, although each cell line does not express the same cytokeratins. One of the lines expresses CD90, which is associated with a fibroblast lineage. Each of the cell lines expresses low to moderate amounts of class I MHC molecules, and several of them express low to moderate amounts of class II MHC molecules. Using a combination of PCR and flow cytometry, it was determined that each cell line expressed between six and thirteen of fifteen antigens tested. Little to no TGF-β3 was produced by any of the cell lines, TGF-β1 was produced by three of the cell lines, TGF-β2 was produced by all of the cell lines, with four of the cell lines producing large amounts of the latent form of the molecule, and IL-10 was produced by one of the cell lines. Conclusions Each of the 11 ovarian cancer lines is characterized by a unique expression pattern of epithelial/fibroblast markers, MHC molecules, tumor antigens, and immunosuppressive cytokines. Knowledge of these unique expression patterns will increase the usefulness of these cell lines in identifying the antigens recognized by ovarian cancer-specific CTL.