Human carcinoma cell lines xenografted in athymic mice: biological and antigenic characteristics of an intraabdominal model

Summary In order to investigate in vivo clinical applications of murine monoclonal antibodies directed against human ovarian carcinoma a preclinical in vivo model was developed using BALB/c athymic mice. Three human carcinoma cell lines (MCF7, HT29, and SW626) were injected into the peritoneal cavity of pristane-primed animals and the biological and antigenic characteristics of the i.p. grown tumors were studied. The animals were killed when moribund or 6–8 weeks after tumor injection. At autopsy tumor take was observed in 85% of the injected animals, whereas palpable nodules were evident in only 83%. Examination of the peritoneal cavity revealed intraabdominal carcinomatosis with tumor masses varying in size between 0.2 and 0.5 cm in diameter and tumor sheets. The most frequently affected organs were the diaphragm, the liver, and the reproductive system. Ascitic fluid formation was rare and no animal developed tumors outside the peritoneal cavity. To determine whether the in vivo tumors retained the same antigenic characteristics as the in vitro cell lines, four monoclonal antibodies (MBrl, MOv2, MOv8, and MOv15) directed against ovarian carcinoma-associated antigens and two different experimental approaches (immunofluorescence and immunoblotting) were used. Variations at either a quantitative or a qualitative level were observed for some antigens, whereas no evident changes were apparent for others. In particular, the antigens detected by MBr1 and MOv15 on the MCF7 line both maintained high levels of expression and immunoblotting staining pattern, whereas the antigens detected by MOv2 on the HT29 and SW626 lines, although present at a high level, clearly changed their staining pattern. As regards the antigens recognized by MOv8 and MOv15 on the HT29 and SW626 lines, we observed a drastic decrease in the level of their expression and in many cases a drop below the threshold of detectability of the test. The intraabdominal carcinomatosis described partially mimics the growth characteristics of human ovarian cancer and maintains the expression of some antigenic markers associated with epithelial tumors of the ovary and may therefore be useful in devising immunodiagnostic and/or immunotherapeutic strategies for ovarian carcinoma.     

The sensitivities of SV40-transformed human fibroblasts to monofunctional and DNA-crosslinking alkylating agents.

4 repair-deficient (Mer-) and 2 repair-proficient (Mer+) lines of SV40-transformed human fibroblasts were assayed for colony-forming ability after treatment with MNNG, methyl methanesulfonate (MMS), 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), and 1-(2-chloroethyl)-3-(2-hydroxyethyl)-1-nitrosourea (HECNU). The sensitivities to MMS, BCNU and HECNU of these SV40-transformed lines were similar to those of comparably treated human tumor cells observed previously. However, unlike human tumor lines, whose post-MNNG survival is strongly dependent upon Mer phenotype, SV40-transformed lines showed a lack of dependence of post-MNNG colony-forming ability on Mer phenotype. No differences in glutathione levels that might explain these differences were detected. The amounts of SV40-specific DNA and RNA among the lines were found to vary widely, but no correlation with Mer phenotype was found.     

Screening for mutations in the neurofibromatosis type 2 (NF2) gene in sporadic meningiomas

Meningiomas are benign tumors of the central nervous system. They are usually sporadic but can also occur associated with the neurofibromatosis type 2 (NF2) syndrome. The gene responsible for NF2, recently isolated from chromosome 22, encodes a membrane-organizing protein that shows high sequence homology to a protein family thought to link the cytoskeleton with membrane proteins. Mutations of the NF2 gene have been described in sporadic meningiomas, exclusively in tumors that show loss of heterozygosity (LOH) of 22q. These preliminary results indicate that the NF2 gene is involved in the pathogenesis of at least a subset of meningiomas, where it does indeed behave as a tumor suppressor gene. In order to characterize better the role of the NF2 gene in the genesis of meningiomas we have examined the entire coding sequence of the gene in 125 meningiomas by single-strand conformational polymorphism analysis; furthermore, LOH analysis for markers of 22q has been carried out. Inactivating mutations were identified in 30% of our samples, all of which also showed LOH of 22q. The majority of mutations identified were frameshifts and nonsense mutations, which are predicted to produce a truncated or non-functional protein. We also found two missense and three in-frame deletions that may pinpoint specific regions of the protein critical to its function. Furthermore, the distribution of mutations throughout the gene, suggested that exons 2, 3, 5, 11 and 13 are more frequently involved. Our results reconfirm the importance of the NF2 gene in the pathogenesis of meningiomas and also suggest that there may be a nonrandom clustering of mutations throughout the gene.     

Specific induction of self-discrimination by follicle cells in Ciona intestinalis oocytes

Self-incompatibility, a mechanism that prevents self-fertilization in ascidians, is based on the ability of the oocyte vitelline coat to distinguish and accept only heterologous spermatozoa. In Ciona intestinalis self-discrimination is established during late oogenesis and is contributed or controlled by products of the overlying follicle cells. In this study we have further investigated the role of the follicle cells in the onset of self-discrimination by using in vitro maturation of ovarian oocytes deprived of the follicle cells and incubated with either autologous or heterologous follicle cells. Fertilization assays demonstrate that the action of the follicle cells is exerted even when they are detached from the vitelline coat and that only autologous follicle cells can promote the induction of self-sterility on the egg coat. Electron microscopy of the oocytes during maturation reveals that the switch from self-fertility to self-sterility is accompanied by the appearance of a thin electron-dense layer on the outer surface of the vitelline coat. We suggest that the formation of this layer is the result of the interaction between products of the follicle cells and the autologous vitelline coat.     

Characterization of a Small Family (CAIII) of Microsatellite-Containing Sequences with X-Y Homology

Four X-linked loci showing homology with a previously described Y-linked polymorphic locus (DYS413) were identified and characterized. By fluorescent in situ hybridization (FISH), somatic cell hybrids, and YAC screening, the X-linked members of this small family of sequences (CAIII) all map in Xp22, while the Y members map in Yq11. These loci contribute to the overall similarity of the two genomic regions. All of the CAIII loci contain an internal microsatellite of the (CA)_n type. The microsatellites display extensive length polymorphism in two of the X-linked members as well as in the Y members. In addition, common sequence variants are found in the portions flanking the microsatellites in two of the X-linked members. Our results indicate that, during the evolution of this family, length variation on the Y chromosome was accumulated at a rate not slower than that on the X chromosome. Finally, these sequences represent a model system with which to analyze human populations for similar X- and Y-linked polymorphisms. Received: 29 July 1996 / Accepted: 15 January 1997     

The measurement of chemically-induced DNA repair synthesis in human cells by BND-cellulose chromatography.

Repair synthesis in human cells in tissue culture can be readily separated from semi-conservative DNA synthesis with the aid of a benzoylated naphthoylated DEAE cellulose (BND-cellulose) column. Cells are incubated with a radioactive DNA precursor during treatment with a repair-inducing agent. An inhibitor of semi-conservative DNA synthesis (hydroxyurea) is added to slow the progression of the DNA growing point. The cells are lysed and after treatment with ribonuclease and pronase the lysates are sheared and passed through a BND-cellulose column. Native DNA is eluted with I M NaCl. Any increase in radioactivity in the native DNA is due to repair synthesis and the specific repair activity (nucleotides inserted per mug of DNA) can be determined from radioactivity and absorbancy measurements. Repair can also be measured in the region of the DNA growing point by fractionation of the material eluted from BND-cellulose with 50% formamide. Repair was not detected in N-acetoxy-2-acetylaminofluorene (AAAF)-treated lymphoblasts derived from an individual with xeroderma pigmentosum although methyl methanesulfonate (MMS)-induced repair was observed in these cells.     

Decomposition of woody debris in Mediterranean ecosystems: the role of wood chemical and anatomical traits

Plant and Soil - Data about woody debris (WD) decomposition are very scarce for the Mediterranean basin. The specific aim of this work is to explore the relationships between WD traits with the...     

Carbohydrate based meningococcal vaccines: past and present overview

Glycoconjugate Journal - Neisseria meningitidis is a major cause of bacterial meningitidis worldwide. Children less than five years and adolescents are particularly affected. Nearly all invasive...