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Biomedical subjects

J Mark

Publications and source records attributed to J Mark.

At least 91 records · Page 5Linked to original sources
PubMed1988

Aberrant expression of receptors for platelet-derived growth factor in an anaplastic thyroid carcinoma cell line.

Receptors for platelet-derived growth factor (PDGF) have previously only been found on cells of mesenchymal and glial origin. This study shows PDGF receptors on an anaplastic thyroid carcinoma cell line, C 643, that was found to express thyroglobulin mRNA, confirming its origin from thyroid epithelium. Northern blot analysis of poly(A)+ RNA hybridized with a human PDGF B-type receptor cDNA probe revealed a 5.4-kilobase transcript in the C 643 cells. The existence of receptor protein on the cell surface was shown by immunofluorescence microscopy with a PDGF receptor monoclonal antibody. Binding experiments with 125I-labeled dimeric forms of PDGF indicated that the cells contain B-, but not A-, type PDGF receptors. The addition of PDGF to C 643 membranes in the presence of [32P]ATP induced phosphorylation of the receptor. A polyclonal PDGF B-type receptor peptide antiserum was used to immunoprecipitate a receptor protein from metabolically labeled C 643 cells; the receptor was found to be 5-10 kDa larger than that in normal human fibroblasts. Removal of N-linked carbohydrates using endoglycosidase H resulted in deglycosylated receptor proteins of similar size in C 643 cells and fibroblasts, indicating differences in glycosylation patterns of the two receptor proteins. The aberrant expression of receptors might be crucial in tumor development by conferring a selective growth advantage to the cancer cells.

Blotting, Northern↗
PubMed1987

Evidence for progressional changes in the human malignant glioma line U-343 MGa: analysis of karyotype and expression of genes encoding the subunit chains of platelet-derived growth factor.

Three cell samples in different passages of the line U-343 MGa, derived from a human malignant glioma biopsy, gave rise to clones with different amounts of platelet-derived growth factor (PDGF)-like activity secreted to extracellular medium, and of 125I-labeled PDGF binding. Sixteen clones were completely karyotyped with the G-banding technique. The unique markers 1p-q+, 16p- found in all clones, as well as in the parallel uncloned line, U-343 MG, provided evidence of their common origin. The deduced early, possibly partly primary, deviations had the formula 44, XY, 1p-q+, -14, 16p-, -22, where loss of one chromosome 22 is in accordance with previous reports on early chromosomal deviations in gliomas. Two clones, the hypodiploid 26L and 5H, represented early progressional changes. The other clones followed two patterns of late progressional changes, probably starting from the karyotype of 5H, with additional markers and doubling of the stemlines. In late progressional line I 12q+ and in II +7 were the most characteristic findings. Northern blot analysis using complementary DNA clones for the A and B chains of PDGF showed that both PDGF chains were expressed in 26L and 5H indicating that activation of the PDGF genes could have been an early event in the development of this glioma. Clones with late progression pattern II had been subjected to the highest selective pressure in vitro, and they secreted the highest amount of PDGF-like activity to the extracellular medium. Among them were the most rapidly and tightly growing cells and some clones with high 125I-labeled epidermal growth factor binding. Possibly these findings reflect progressional changes including defective regulation of the growth factor/growth factor receptor genes, selected for in vitro, without involving gross rearrangements or amplifications of the genes. The possible significance of extra chromosomes 7, with the PDGF A chain and epidermal growth factor receptor genes, and of the 12q+ marker, located near the gamma interferon gene is discussed.

Cell Line↗
PubMed1987

Relationship between gene amplification and chromosomal deviations in malignant human gliomas.

Biopsies of 33 malignant human gliomas were karyotyped and evaluated for amplification (more than eight gene copies per cell) of the epidermal growth factor receptor (EGFR), N-myc, c-myc, and gli genes by Southern blot analysis. Fifteen of 33 tumors showed amplification of EGFR, none had amplified c-myc, one tumor had amplified N-myc, and one had amplification of gli. Thirteen of the 16 (81%) evaluable tumors with gene amplification contained double minutes (DM), and only four of 16 (25%) tumors without demonstrable amplification contained these structures. Polysomy for chromosome #7, in contrast, occurred in 58% of tumors with EGFR amplification and 53% of tumors without amplification of the gene. Structural abnormalities of 7p occurred in two tumors with EGFR amplification and in one tumor without amplification of this gene. These studies suggest that DM are the usual locus for amplified genes (usually EGFR) in human glioma biopsies, but that structural abnormalities of 7p may be associated with EGFR amplification in a small proportion of these tumors. The presence of polysomy 7, however, probably is unrelated to amplification of the EGFR gene.

Chromosome Aberrations↗
PubMed1987

Chromosomal progression of malignant human gliomas from biopsy to establishment as permanent lines in vitro.

Karyotypes of four malignant human gliomas were followed from direct preparation and/or short-term culture through their establishment in vitro to determine whether the cultured cells maintained the original karyotypes, or were the products of selection, progression, or alteration in vitro. The karyotypes of these four human glioma-derived cell lines showed the same evolutionary pattern consisting of a doubling of the stem line or a closely related population; one line changed ploidy again to near-pentaploid. Marker types seen originally were generally retained, but new markers were acquired in the later passages. We concluded that the eventual chromosomal compositions of these four human glioma-derived cell lines were the products of karyotypic evolution, rather than simple selection of a minor population of polyploid cells.

Cell Line↗
PubMed1987

Polyclonal chromosomal evolution in a benign mixed salivary gland tumor.

Banding analyses of a human benign pleomorphic adenoma in the parotid gland revealed a polyclonal pattern where structural rearrangements predominated. These deviations were different from the anomalies previously observed in 100 mixed tumors. The reason found for the differences in all likelihood was x-ray treatment of tuberculous lymphadenitis in the neck during childhood. Implications regarding origin and development of pleomorphic adenomas are discussed.

Adenoma, Pleomorphic↗
PubMed1986

Preferential glutamine uptake in rat brain synaptic mitochondria.

Glutamine uptake has been studied in purified rat brain mitochondria of synaptic or non-synaptic origin. It was taken up by an active saturable transport mechanism, with an affinity two-times higher in synaptic than in non-synaptic mitochondria (Km = 0.45 and 0.94 mM, respectively). Vmax of uptake was 7-times higher in synaptic mitochondria (Vmax = 9.2 and 1.3 nmol/min per mg protein, respectively). Glutamine transport was found to be inhibited by L-glutamate (IC50 = 0.64 mM) as well as thiol reagents (mersalyl, N-ethylmaleimide). It is suggested that differential uptake of glutamine in mitochondria of synaptic or non-synaptic origin may be a major mechanism in the regulation of the synthesis of the neurotransmitter glutamate.

Animals↗
PubMed1986

Observations by G-banding in benign odontogenic tumors.

The G-banding patterns in five cultured benign odontogenic tumors are described. Abnormal stem sideline karyotypes were observed in two tumors, whereas the remaining three tumors had a normal stemline. The latter cases, however, contained different types of variant cells, often showing deviations of nonrandom character. The results are discussed in relation to chromosomal findings in other benign tumor types and, briefly, in relation to oncogenes. A stepwise evolutionary pattern, which might be common to all benign tumor types, is suggested.

Adolescent↗
PubMed1986

Specific chromosomal abnormalities characterize four established cell lines derived from malignant human gliomas.

The four permanent human glioma-derived cell lines reported here are the first such lines for which the karyotypes have been followed from the original biopsies through the establishment of the lines in culture. Although ploidy changes were seen, each line retained either distinctive marker chromosomes or the overall original chromosomal distribution allowing the origin of each line to be established with certainty. D-263 MG expresses glial fibrillary acidic protein, all lines except D-245 MG are tumorigenic in athymic mice, and each line displays a unique pattern with respect to in vitro growth parameters and expression of biochemically defined markers, oncofetal antigens and lymphoid-associated markers. D-245 MG and D-259 MG are able to grow in the absence of supplemental glutamine; glutamine synthetase was detected in these cell lines both by immunocytochemistry and by direct assay. Thus, the four permanent human glioma-derived cell lines described here are representative of glioma lines in their general characteristics. D-259 MG retains numerous double minute chromosomes (DMs), D-263 MG contains two marker chromosomes with breaks in 9p, and D-247 MG and D-245 MG with stemlines containing 96 and 89 chromosomes contain eight and six normal copies (respectively) of chromosome No. 7. The retention in these four cell lines of the most common chromosomal abnormalities seen in biopsies of malignant human gliomas provides the opportunity to investigate the meaning of these specific chromosomal changes.

Animals↗
PubMed1986

6q- and loss of the Y chromosome--two common deviations in malignant human salivary gland tumors.

Nine cases of malignant human salivary gland tumors cultured in vitro were subjected to detailed cytogenetic analysis with G-banding. Together with observations from three earlier published cases, the results of 12 cases were surveyed: five adenoid cystic carcinomas, three acinic cell tumors, three adenocarcinomas, and one mucoepidermoid carcinoma. All tumors had stemlines in the diploid-near-diploid mode. The most consistent changes among the adenoid cystic carcinomas were stem lines and/or variant cells with anomalies affecting the terminal part of 6q (i.e., 6q 16-25). Deviations affecting the Y chromosome (losses) and, to a lesser extent, #6 (structural changes) and #8 (gains) characterized the early karyotypic evolution in acinic cell tumors. Two of the three analyzed adenocarcinomas showed stemlines or variant cells with loss of gonosomes. The karyotypic features of the different tumor types, including primary changes, evolutionary characteristics, and progressional pathways, are discussed. The cytogenetic relationships between benign and malignant salivary gland tumors also will be considered.

Adenocarcinoma↗
PubMed1986

Chromosomal evolution in malignant human gliomas starts with specific and usually numerical deviations.

Our previous karyotypic studies of malignant human gliomas have demonstrated that their most consistent early or primary gross changes include gains of #7, losses of #10, #22, and the gonosomes, and the presence of double minutes. Karyotypes of 15 additional malignant human gliomas reported here have confirmed these observations and, by enlarging our series, we can now show that in addition to double minutes, certain other gross structural abnormalities also are clearly associated with the early evolution of this type of tumor. The most prevalent deviations are deletions and translocations involving 9p. Other chromosomes commonly involved in rearrangements are #1, #6, and #13, and less frequently #7, #11, and #16.

Adult↗
PubMed1985

Selective culture of neurons from rat cerebral cortex: morphological characterization, glutamate uptake and related enzymes during maturation in various culture media.

Dissociated cerebral cortex of fetal rat was grown in a serum-free, chemically defined medium (CDM) (containing insulin, progesterone, estradiol, transferrin, putrescine, selenium and 15 mM KCl) and compared with cultures grown in a medium containing 20% fetal calf serum (SCM). Neurons survived well using either medium, but in the serum-free medium the cellular population was exclusively neuronal (at 96%), while glial cells began to proliferate after one week in the SCM. The various cellular morphologies are described in the present report and the presence of immunological markers characteristic of neurons was investigated. Autoradiographic experiments have been performed after incubation with various putative neurotransmitters and we have shown the presence of a strikingly high proportion of glutamatergic neurons in these cultures. Glutamate high affinity uptake was also greatly increased in neuronal cultures maintained in a CDM compared to a SCM, especially in young cultures. The development of different enzymes involved in the metabolism of glutamate was also studied; the specific activity of glutaminase increased in culture and was found to be higher in a CDM than in a SCM, while the inverse was true for glutamine synthetase. The relative proportion of both enzymes in neurons compared to glial cells was opposite, as neuronal cultures had higher levels of glutaminase and glial cultures were enriched in glutamine synthetase activity. It seems that the proportion of glutamate-neurons increases when cultured in a CDM compared to a SCM and we suggest that this culture procedure may provide a purely neuronal population enriched in mature glutamatergic neurons. It may thus be useful for future in vitro studies on glutamate and GABA metabolism in neurons.

Animals↗
PubMed1985

A serially transplantable human giant cell glioblastoma that maintains a near-haploid stem line.

We have karyotyped a human giant cell glioblastoma removed from an 11-year-old girl and have established from it a subcutaneously transplantable line in athymic nude mice. The original tumor contained near-haploid cells with 25 or 26 chromosomes, including two copies of #1, (7 or 7p+) and #18. There were also hyperdiploid (49-52) cells that were tetraploid for these same three chromosome types; doubled versions of the hyperdiploid population were also seen. The stemline of the mouse-grown tumor was 26,X, +1, +7p+, +18 in the first passage and has remained consistently near-haploid through ten serial in vivo passages. Growth stabilization has occurred with an average latency of less than 3 months. This transplantable line is available for evaluating chemotherapeutic responsiveness of human giant cell glioblastoma and for studying near-haploidy in solid human tumors.

Animals↗
PubMed1985

Intermediate filaments in cultured human pleomorphic adenomas. An immunohistochemical study.

Primary cultures of 9 benign human pleomorphic adenomas were analyzed by immunofluorescence and antibodies against the different intermediate filaments and microfilaments. The cultured cells were also cytogenetically characterized by G- and C-banding techniques. The adenoma cells expressed at least three different classes of intermediate filaments, viz. prekeratin, vimentin and glial fibrillary acidic protein (GFA). No correlation between chromosomal pattern and intermediate filament expression was found. The frequency of cells stained for each of the different antibodies varied considerably among the tumours. Prolonged culturing appeared to induce a reduction of cells positive for prekeratin. This was probably a true loss of antigens and not an effect of overgrowth of stromal cells. It is concluded that the cells studied, on the basis of several criteria, are of neoplastic origin. This in vitro system appears to be well suited for further histogenetic studies on pleomorphic adenomas.

Actin Cytoskeleton↗