Unique chromosomal rearrangement and mucin production in a novel salivary myoepithelial cell strain

Multiple unrelated translocations in a metastatic epimyoepithelial carcinoma of the parotid gland

We report the cytogenetic, fluorescence in-situ hybridization (FISH) and DNA flow cytometric analysis of a rare metastatic epimyoepithelial carcinoma of the parotid gland to the lung with a clinical course of 29 years. DNA content and FISH analyses of tumor and short-term culture cells showed diploid DNA content and lack of numerical chromosomal abnormalities. Immunohistochemical analysis of the short-term culture cells showed predominantly keratin positive and sparse desmin staining supporting an epithelial rather than myoepithelial origin. Cytogenetic analysis showed 46,XY karyotype with clonal translocations of t(3;22)(q13.2;q13.1), t(1;7)(q21;q22), t(8;9)(p10;p10), and t(5;6) (q35;q21). Our findings indicate that these alterations developed in a diploid stemline during tumor progression and in the epithelial component of this tumor.

Establishment and characterization of a novel human myoepithelial cell line and matrix-producing xenograft from a parotid basal cell adenocarcinoma

Myoepithelial cells exert important paracrine effects on epithelial morphogenesis and mitogenesis through direct cell-cell interactions and through synthesis of a basement membrane extracellular matrix. To study these effects further, this study established the first immortalized human myoepithelial cell line, HMS-1, and transplantable xenograft, HMS-X, from the rare parotid basal cell adenocarcinoma. The cell line exhibited a fully differentiated myoepithelial phenotype and the xenograft exhibited the rare property of accumulating an abundant extracellular matrix composed of both basement membrane and nonbasement membrane components with the latter predominating. With HMS-1 as a feeder layer, dramatic and specific induction of epithelial morphogenesis (spheroid formation) occurred with selected normal epithelial and primary carcinoma target cells. HMS-1 and HMS-X provide distinct advantages over the conventional murine matrices in existence. They will be invaluable in future studies of human tumor-myoepithelial and matrix interactions important for tumor cell growth, invasion, and metastasis.

Overexpression of human aspartyl(asparaginyl)beta-hydroxylase in hepatocellular carcinoma and cholangiocarcinoma

To characterize genes that become upregulated with malignant transformation of human hepatocytes, a library of monoclonal antibodies was produced against the FOCUS hepatocellular carcinoma cell line. Antibody FB-50 reacted with an antigen that was highly expressed in 4 of 10 primary hepatocellular carcinomas, in all 20 cholangiocarcinomas we studied, and in a variety of transformed cell lines. This antigen was also highly expressed in neoplastic epithelial cells of breast and colon carcinomas in contrast to its low level of expression in normal hepatocytes and in non-neoplastic epithelial cells. Among the normal adult tissues studied, high levels were observed only in proliferating trophoblastic cells of the placenta and in adrenal glands. A 636-bp partial cDNA, isolated from a gamma GT11 expression library generated with HepG2 human hepatoblastoma cells, and a complete cDNA, generated by reverse transcriptase-PCR, identified the antigen as the human form of aspartyl(asparaginyl)beta-hydroxylase. This enzyme catalyzes posttranslational hydroxylation of beta carbons of specific aspartyl and asparaginyl residues in EGF-like domains of certain proteins. Analyses of extracts prepared from several human tumor cell lines compared to their normal tissue counterparts indicate that the increase in hydroxylase, approximately 10-fold, is controlled at the level of transcription and the protein is expressed in an enzymatically active form. In similar analyses, comparing hepatocellular carcinomas to adjacent uninvolved liver from five patients, enzymatic activity was much higher in the tumor tissue from the four patients whose immunoblots revealed increased hydroxylase protein in the malignant tissue. EGF repeats in the extracellular domain of Notch or its homologs contain the consensus sequence for hydroxylation. Deletion mutants lacking this domain are gain-of-function mutants, suggesting that the domain modulates signal transduction by the cytoplasmic domain. While the function imparted by beta hydroxylation is unknown, our studies raise the possibility that beta hydroxylation is regulated in proteins like the mammalian Notch homologs, whose cytoplasmic domains have been shown to be oncogenic.

A fluorescence in situ hybridization (FISH) analysis with centromere-specific DNA probes of chromosomes 3 and 17 in pleomorphic adenomas and adenoid cystic carcinomas

Aberrations of chromosomes 3 and 17 were studied by FISH using centromere-specific DNA probes in 11 salivary adenoid cystic carcinomas (ACC) and 8 salivary pleomorphic adenomas (PA), with 3 lymph nodes as controls. Two hybridized signals were detected in 92.8 +/- 2.7% of controls, 73.2 +/- 7.0% of PA and 66.8 +/- 7.9% of ACC cells for chromosome 3, and in 90.4 +/- 2.3% of controls, 59.5 +/- 25.0% of PA and 44.8 +/- 20.2% of ACC for chromosome 17. More than 3 hybridized signals, which indicate polysomy, were observed in 3.1% of controls, 15.5% of PA and 22.9% of ACC cells for chromosome 3, and in 1.2% of controls, 10.3% of PA and 23.1% of ACC cells for chromosome 17. A single hybridized signal was much more frequent for chromosome 17 than for chromosome 3. These findings suggest that polysomy of both chromosomes occurs during the development of salivary gland tumors, and its frequency is increased in adenoid cystic carcinoma as compared to pleomorphic adenoma. In addition, monosomy of chromosome 17 could possibly be significant in salivary gland tumors.