(1/9318) Classification of human colorectal adenocarcinoma cell lines.
Eleven human colorectal adenocarcinoma cell lines established in this laboratory were classified into three groups based on morphological features (light and electron microscopy), modal chromosome number, and ability to synthesize carcinoembryonic antigen (CEA). Group 1 cell lines contained both dedifferentiated and differentiating cells growing in tight clusters or islands of epithelium-like cells; their modal chromosome number was about 47, and they synthesized small to moderate amounts of CEA. Group 2 cell lines were more dedifferentiated, were hyperdiploid, and synthesized small amounts of CEA. Group 3 cell lines were morphologically similar to those of Group 1 by light microscopy. They differed ultrastructurally by containing microvesicular bodies; the modal chromosome number varied from hyperdiploid to hypertriploid or they had bimodal populations of hypodiploid and hypertriploid cells, and they synthesized relatively large amounts of CEA. No correlation could be found between Broder's grade or Duke's classification of the original tumor and modal chromosome number or ability to synthesize CEA. These findings support Nowell's hypothesis that the stem line is different for each solid tumor, which makes it difficult to relate chromosomal changes to the initiation of the neoplastic state. (+info)
(2/9318) Cloning of a novel gene specifically expressed in clonal mouse chondroprogenitor-like EC cells, ATDC5.
We cloned a full-length cDNA encoding a novel mouse protein, A-C2, by differential display method using mouse embryonic fibroblast C3H10T1/2 cells and mouse chondroprogenitor-like EC cells, ATDC5. The deduced amino acid sequence of A-C2 consisted of 106 amino acids with no significant homology to the sequences previously reported. Northern blot analysis showed two major bands of 2.1 and 1.8 kb sizes. Expression of A-C2 mRNA was exclusive to ATDC5 cells at their undifferentiated stage. None of ATDC5 cells at their differentiated stage and adult mice tissues examined expressed A-C2 gene. (+info)
(3/9318) Crystal structures of two H-2Db/glycopeptide complexes suggest a molecular basis for CTL cross-reactivity.
Two synthetic O-GlcNAc-bearing peptides that elicit H-2Db-restricted glycopeptide-specific cytotoxic T cells (CTL) have been shown to display nonreciprocal patterns of cross-reactivity. Here, we present the crystal structures of the H-2Db glycopeptide complexes to 2.85 A resolution or better. In both cases, the glycan is solvent exposed and available for direct recognition by the T cell receptor (TCR). We have modeled the complex formed between the MHC-glycopeptide complexes and their respective TCRs, showing that a single saccharide residue can be accommodated in the standard TCR-MHC geometry. The models also reveal a possible molecular basis for the observed cross-reactivity patterns of the CTL clones, which appear to be influenced by the length of the CDR3 loop and the nature of the immunizing ligand. (+info)
(4/9318) Analysis of V(H)-D-J(H) gene transcripts in B cells infiltrating the salivary glands and lymph node tissues of patients with Sjogren's syndrome.
OBJECTIVE: In patients with Sjogren's syndrome (SS), B lymphocytes have been found to infiltrate salivary glands, resulting in sialadenitis and keratoconjunctivitis. The disease is frequently associated with benign and neoplastic lymphoproliferation. The present study was undertaken to investigate whether clonal B cell expansion takes place in lymphocytic infiltrations of salivary glands under (auto- [?]) antigen stimulation, by analyzing in more detail the variable part (V(H)-D-J(H)) of the immunoglobulin heavy chain genes expressed in these B cells. METHODS: Biopsies of the labial salivary glands and lymph nodes were performed on 2 female patients with SS. The Ig gene rearrangements in these tissues were amplified by reverse transcriptase-polymerase chain reaction using specific primers. RESULTS: A total of 94 V(H)-D-J(H) transcripts were cloned and sequenced. Our data suggest a polyclonal origin of the B cell infiltrates. In 92 of the transcripts, V(H) genes were modified by somatic mutation. Further analysis showed counterselection for replacement mutations within the framework regions, suggesting that those B cells were stimulated and selected for functional expression of a surface Ig. In labial salivary glands from both patients, clonally related B cells became evident. Members of 1 particular clone were found in both the lip and lymph node material. CONCLUSION: These data provide evidence, on the nucleotide sequence level, that an antigen-triggered clonal B cell expansion takes place in the salivary glands of patients with SS who do not have histologic evidence of developing lymphoma. It may be speculated that those B cell clones expand during disease progression, resulting in lymphomagenesis. (+info)
(5/9318) Isolation and characterization of two mouse L cell lines resistant to the toxic lectin ricin.
Two variant mouse L cell lines (termed CL 3 and CL 6) have been selected for resistant to ricin, a galactose-binding lectin with potent cytotoxic activity. The resistant lines exhibit a 50 to 70% decrease in ricin binding and a 300- to 500-fold increase in resistance to the toxic effects of ricin. Crude membrane preparations of CL 3 cells have increased sialic acid content (200% of control), while the galactose, mannose, and hexosamine content is within normal limits. Both the glycoproteins and glycolipids of CL 3 cells have increased sialic acid, with the GM3:lactosylceramide ratios for parent L and CL 3 cells being 0.29 and 1.5, respectively. In contrast, the membranes of CL 6 cells have a decrease in sialic acid, galactose, and hexosamine content with mannose being normal. Both cell lines have specific alterations in glycosyltransferase activities which can account for the observed membrane sugar changes. CL 3 cells have increased CMP-sialic acid:glycoprotein sialyltransferase and GM3 synthetase activities, while CL 6 cells have decrease UDP-GlcNAc:glycoproteinN-acetylglucosaminyltransferase and DPU-galactose:glycoprotein galactosyltransferase activities. The increased sialic acid content of CL 3 cells serves to mask ricin binding sites, since neuraminidase treatment of this cell line restores ricin binding to essentially normal levels. However, the fact that neuraminidase-treated CL 3 cells are still 45-fold resistant to ricin indicates that either a special class of productive ricin binding sites is not being exposed or that the cell line has a second mechanism for ricin resistance. (+info)
(6/9318) Enhanced tumor growth and invasiveness in vivo by a carboxyl-terminal fragment of alpha1-proteinase inhibitor generated by matrix metalloproteinases: a possible modulatory role in natural killer cytotoxicity.
Matrix metalloproteinases (MMPs) are believed to contribute to the complex process of cancer progression. They also exhibit an alpha1-proteinase inhibitor (alphaPI)-degrading activity generating a carboxyl-terminal fragment of approximately 5 kd (alphaPI-C). This study reports that overexpression of alphaPI-C in S2-020, a cloned subline derived from the human pancreas adenocarcinoma cell line SUIT-2, potentiates the growth capability of the cells in nude mice. After stable transfection of a vector containing a chimeric cDNA encoding a signal peptide sequence of tissue inhibitor of metalloproteinase-1 followed by cDNA for alphaPI-C into S2-020 cells, three clones that stably secrete alphaPI-C were obtained. The ectopic expression of alphaPI-C did not alter in vitro cellular growth. However, subcutaneous injection of the alphaPI-C-secreting clones resulted in tumors that were 1.5 to 3-fold larger than those of control clones with an increased tendency to invasiveness and lymph node metastasis. These effects could be a result of modulation of natural killer (NK) cell-mediated control of tumor growth in nude mice, as the growth advantage of alphaPI-C-secreting clones was not observed in NK-depleted mice, and alphaPI-C-secreting clones showed decreased NK sensitivity in vitro. In addition, production of alphaPI and generation of the cleaved form of alphaPI by MMP were observed in various human tumor cell lines and in a highly metastatic subline of SUIT-2 in vitro. These results provide experimental evidence that the alphaPI-degrading activity of MMPs may play a role in tumor progression not only via the inactivation of alphaPI but also via the generation of alphaPI-C. (+info)
(7/9318) Organ-selective homing defines engraftment kinetics of murine hematopoietic stem cells and is compromised by Ex vivo expansion.
Hematopoietic reconstitution of ablated recipients requires that intravenously (IV) transplanted stem and progenitor cells "home" to organs that support their proliferation and differentiation. To examine the possible relationship between homing properties and subsequent engraftment potential, murine bone marrow (BM) cells were labeled with fluorescent PKH26 dye and injected into lethally irradiated hosts. PKH26(+) cells homing to marrow or spleen were then isolated by fluorescence-activated cell sorting and assayed for in vitro colony-forming cells (CFCs). Progenitors accumulated rapidly in the spleen, but declined to only 6% of input numbers after 24 hours. Although egress from this organ was accompanied by a simultaneous accumulation of CFCs in the BM (plateauing at 6% to 8% of input after 3 hours), spleen cells remained enriched in donor CFCs compared with marrow during this time. To determine whether this differential homing of clonogenic cells to the marrow and spleen influenced their contribution to short-term or long-term hematopoiesis in vivo, PKH26(+) cells were sorted from each organ 3 hours after transplantation and injected into lethally irradiated Ly-5 congenic mice. Cells that had homed initially to the spleen regenerated circulating leukocytes (20% of normal counts) approximately 2 weeks faster than cells that had homed to the marrow, or PKH26-labeled cells that had not been selected by a prior homing step. Both primary (17 weeks) and secondary (10 weeks) recipients of "spleen-homed" cells also contained approximately 50% higher numbers of CFCs per femur than recipients of "BM-homed" cells. To examine whether progenitor homing was altered upon ex vivo expansion, highly enriched Sca-1(+)c-kit+Lin- cells were cultured for 9 days in serum-free medium containing interleukin (IL)-6, IL-11, granulocyte colony-stimulating factor, stem cell factor, flk-2/flt3 ligand, and thrombopoietin. Expanded cells were then stained with PKH26 and assayed as above. Strikingly, CFCs generated in vitro exhibited a 10-fold reduction in homing capacity compared with fresh progenitors. These studies demonstrate that clonogenic cells with differential homing properties contribute variably to early and late hematopoiesis in vivo. The dramatic decline in the homing capacity of progenitors generated in vitro underscores critical qualitative changes that may compromise their biologic function and potential clinical utility, despite their efficient numerical expansion. (+info)
(8/9318) Phenotypic and functional characterization of CD8(+) T cell clones specific for a mouse cytomegalovirus epitope.
A series of CD8(+) T cell clones, specific for the IE1 epitope YPHFMPTNL, of the immediate-early protein 1 of the murine cytomegalovirus (MCMV) were generated in order to determine their protective activity against this infection and correlate their phenotypic markers with antiviral activity. We found that the adoptive transfer of three of these anti-MCMV CD8(+) T cell clones into irradiated naive mice resulted in protection against challenge, while another CD8(+) T cell clone, of the same specificity, failed to confer protection. The clones that conferred protection against lethal challenge reduced greatly viral replication in the lung and other organs of the mice. Using one of the protective anti-MCMV CD8(+) T cell clones we found that in order to be fully protective the cells had to be transferred to recipient mice no later than 1 day after MCMV challenge. The adoptive transfer of these CD8(+) T cell clones also protected CD4(+) T-cell-depleted mice. Phenotypic characterization of the anti-MCMV clones revealed that the nonprotective clone expressed very low levels of CD8 molecules and produced only small amounts of TNF-alpha upon antigenic stimulation. Most importantly, our current study demonstrates that this MHC class I-restricted IE1 epitope of MCMV is efficiently presented to CD8(+) T cell clones in vivo and further strengthens the possibility of the potential use of CD8(+) T cell clones as immunotherapeutic tools against cytomegalovirus-induced disease. (+info)