Demonstration and genotyping of pestivirus RNA from mammalian cell lines

Mineralization occurred both in fetal rat calvarial cells and UMR 106 osteoblastic cells when they were cultured in medium containing L-ascorbate and beta-glycerophosphate as evidenced by von Kóssa staining as well as deposition of calcium ions and inorganic phosphate in the cells. When compared with corresponding non-mineralized cell cultures, both the mineralized cultures of calvarial cells and UMR 106 cells did not exhibit any change in intracellular bone-specific alkaline phosphatase activities which were measured by wheatgerm lectin precipitation method. Our results support the hypothesis that mineralization may not exert any direct negative feedback on matrix protein synthesis in osteoblasts during bone formation.     

Differential expression of mammalian TRP homologues across tissues and cell lines

Mammalian homologues of the Drosophila trp gene have been invoked as the structural basis for the currents associated with capacitative Ca2+ entry (CCE) in many cell types. Trp homologues are members of a large protein family that may associate as channel subunits providing an explanation for the functional diversity of store-operated channels observed in these cells. However, there is little information as to which of these genes are co-expressed at the cellular level. We have examined the tissue specific expression of five mammalian trp genes and determined which are co-expressed in five different cell lines. The results show tissue- and cell-specific co-expression of multiple trp forms. This implies that the subunit composition of a particular CCE channel may vary depending on the cell type.     

Antiproliferative effect of the piperidine nitroxide TEMPOL on neoplastic and nonneoplastic mammalian cell lines

The stable nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) is widely used as a probe in biophysical studies and as an antioxidant in several experimental models. The potential cytotoxic effects of TEMPOL were tested on a panel of human and rodent cell lines, and the nitroxide proved to be significantly more effective in inhibiting the growth of neoplastic than nonneoplastic cell lines after a 96-h exposure. More detailed studies on MCF-7/WT cells indicate that at least 24 h are necessary for TEMPOL to induce irreversible cell damage, which seems to be related to the reactivity of the nitroxyl group. This observation, together with the antagonistic effect of N-acetylcysteine, suggests an involvement of free radical-mediated processes. Cell cycle studies indicate a biphasic effect of TEMPOL, with a short-term accumulation of the cells in the G1 phase and a later increase in G2/M phase; the pattern of DNA fragmentation observed in TEMPOL-treated cells points to an apoptotic mode of cell death. In conclusion, our data suggest that, while the possible cytotoxic effects of TEMPOL should not be overlooked when using this compound as a biophysical probe or antioxidant, these same properties could be exploited as a novel approach to cancer chemotherapy, especially in tumor cells exhibiting unfavorable characteristics, such as a multidrug-resistant phenotype or loss of hormone receptors.     

Conditionally immortalized cell lines with differentiated functions established from temperature-sensitive T-antigen transgenic mice

Seventy-two healthy males and females serially breathed air and 100% O2 at 1.0 atm abs (1.01 bar; AIR and O2, respectively), then 100% O2 at 2.36 atm abs (2.39 bar, HBO) to establish reference values for chest (CH), leg (LG), and foot (FT) PtcO2. Subjects sequentially a) rested supine with legs extended (baseline); b) elevated their monitored leg; c) returned to supine/extended position; d) assumed a seated, both legs dependent posture; and e) returned to supine/extended position. LG and FT PtcO2 decreased during leg elevation and increased when both legs were dependent during AIR, O2, and HBO (P < 0.0001, respectively). LG PtcO2 of females exceeded that for males in all conditions (P < 0.05 to P < 0.0001). Baseline CH PtcO2 also was greater than LG PtcO2 for all subjects in all conditions (P < 0.01 to P < 0.0001) and greater than FT PtcO2 for all conditions (P < 0.01 to P < 0.0001) except AIR. We conclude that: a) position and hyperoxygenation of an extremity significantly affect PtcO2; b) PtcO2 does not follow a decreasing CH to FT gradient in all conditions; c) a gender difference exists for LG PtcO2; and d) PtcO2 reference data are established for the comparative evaluation and clinical management of problem wounds.     

Heterodimerization-independent functions of cell death regulatory proteins Bax and Bcl-2 in yeast and mammalian cells

The pro-apoptotic protein Bax can homodimerize with itself and heterodimerize with the anti-apoptotic protein Bcl-2, but the significance of these protein-protein interactions remains unclear. Alanine substitution mutations were created in a well conserved IGDE motif found within the BH3 domain of Bax (residues 66-69) and the resulting mutant Bax proteins were tested for ability to homodimerize with themselves and to heterodimerize with Bcl-2. Correlations were made with cell death induction by these mutants of Bax both in mammalian cells where Bax may function through several mechanisms, and in yeast where Bax may exert its lethal actions through a more limited repertoire of mechanisms perhaps related to its ability to form ion channels in intracellular membranes. Two of the mutants, Bax(D68A) and Bax(E69A), retained the ability to homodimerize but failed to interact with Bcl-2 as determined by yeast two-hybrid assays and co-immunoprecipitation analysis using transfected mammalian cells. The Bax(E69A) protein exhibited a lethal phenotype in yeast, which could be specifically suppressed by co-expression of Bcl-2, despite its failure to dimerize with Bcl-2. Both the Bax(D68A) and Bax(E69A) proteins induced apoptosis when overexpressed in human 293 cells, despite an inability to bind to Bcl-2. Moreover, co-expression of Bcl-2 with Bax(D68A) and Bax(E69A) rescued mammalian cells from apoptosis. In contrast, a mutant of Bax lacking the IGDE motif, Bax(DeltaIGDE), was incapable of either homodimerizing with itself or heterodimerizing with Bcl-2 and was inactive at promoting cell death in either yeast or mammalian cells. Although failing to interact with Bcl-2, the Bax(D68A) and Bax(E69A) mutants retained the ability to bind to Bid, a putative Bax-activating member of the Bcl-2 family, and collaborated with Bid in inducing apoptosis. When taken together with previous observations, these findings indicate that (i) Bax can induce apoptosis in mammalian cells irrespective of heterodimerization with Bcl-2 and (ii) Bcl-2 can rescue both mammalian cells and yeast from the lethal effects of Bax without heterodimerizing with it. However, these results do not exclude the possibility that BH3-dependent homodimerization of Bax or interactions with Bax activators such as Bid may either assist or be required for the cell death-inducing mechanism of this protein.     

Pharmacological inhibitors of mammalian fatty acid synthase suppress DNA replication and induce apoptosis in tumor cell lines

Pharmacological inhibitors of the anabolic enzyme, fatty acid synthase (FAS), including the natural product cerulenin and the novel compound c75, are selectively cytotoxic to cancer cells via induction of apoptosis, apparently related to the tumor cell phenotype of abnormally elevated fatty acid synthetic metabolism. As part of a larger effort to understand the immediate downstream effect of FAS inhibition that leads to apoptosis, the effects of these inhibitors on cell cycle progression were examined. Both FAS inhibitors produce rapid, profound inhibition of DNA replication and S phase progression in human cancer cells. The dose responses for fatty acid synthesis inhibition and DNA synthesis inhibition are similar. The kinetics of both effects are rapid, with fatty acid synthesis inhibition occurring within 30 min and DNA synthesis inhibition occurring within 90 min of drug exposure. Meanwhile, apoptotic changes are not detected until 6 h or later after inhibitor exposure. Fatty acid synthetic pathway activity and the magnitude of DNA synthesis inhibition by FAS inhibitors are increased in parallel by withdrawal of lipid-containing serum from the cultures. The mechanism of DNA synthesis inhibition by cerulenin is indirect, because expression of certain viral oncogenes rescues DNA synthesis/S phase progression in cerulenin-exposed cells. The data suggest a direct linkage at a regulatory level, between fatty acid synthesis and DNA synthesis in proliferating tumor cells.     

Comparison of the cytotoxicities of Fusarium metabolites and Alternaria metabolite AAL-toxin to cultured mammalian cell lines

The structure of pyramidatine [1], a new bisamide alkaloid from leaves of Aglaia pyramidata, was determined through extensive nmr studies, including homonuclear COSY, NOESY, APT, HETCOR, and selective INEPT techniques. Revision of the 13C-nmr assignment of piriferine [2], an alkaloid previously isolated from A. pirifera, was achieved by examination of several 2D nmr spectra (homonuclear COSY, NOESY, and HETCOR) and confirmed by selective INEPT nmr experiments. Evaluation of the cytotoxic potential of the two alkaloids, along with two other bisamides from Aglaia odorata, odorine [3] and 5'-epi-odorine [4], was carried out in eleven human cancer cell lines. None of these bisamides showed significant cytotoxicity. Nevertheless, piriferine [2], odorine [3], and 5'-epi-odorine [4] were found to inhibit the growth of the vinblastine-resistant KB cells by enhancing the anticancer activity of vinblastine.     

Variable efficiency of the thymidine kinase/ganciclovir system in human glioblastoma cell lines: implications for gene therapy

The gene therapy strategy using the hsvl-thymidine kinase gene (TK) and ganciclovir (GCV) injections that has been used for treating human glioblastomas has not been as effective as expected after the first animal experiments. A better understanding of the different steps involved in this treatment, like gene transfer, gene expression, and sensitivity of the recipient cells, is needed. After proposing sensitivity criteria for the TK/GCV system and for the bystander effect, based on the levels of GCV that can be reached in vivo, we studied seven human glioblastoma cell lines (U87, U118, U251, SNB19, SNB75, SF295, SF539) for their sensitivity to the TK/GCV system. We also studied their in vitro bystander effect and their in vitro transfectability using LipofectAMINE as a transfection enhancer. Among six human glioblastoma cell lines stably transfected with the TK gene, five were sensitive to TK/GCV, and two had a good in vitro bystander effect. The in vitro transfectability of the cell lines tested was low (< or = 1%) compared to that of an established animal cell line, C6 rat glioma, in which 20-30% of the cells can be transfected routinely. According to this in vitro analysis, most of the glioblastoma cell lines should be sensitive to the TK/GCV system, but there is an urgent need for agents to increase transfection efficiency.     

Hypermutability of UV-treated plasmids in dysplastic nevus/familial melanoma cell lines

Members of cutaneous melanoma (CM) families with dysplastic nevi (DN) are at high risk of developing CM. Using a shuttle vector plasmid, pSP189, cell lines from three patients with CM plus DN were previously found to have elevated post-UV plasmid mutability. To investigate familial occurrence of this cellular phenotype, we examined post-UV plasmid mutability in 31 lymphoblastoid cell lines from 6 familial CM kindreds. In comparison to 16 normal control lines, we found an abnormally elevated post-UV plasmid mutability in cell lines from 13 of 13 patients with CM plus DN (P = 1.5 x 10(-8)) and from 5 of 8 patients with DN only (P = 0.001). Elevated spontaneous plasmid mutation frequency (MF) was also present in cell lines from six of the CM plus DN patients (P = 0.002) and three of the DN-only patients (P = 0.028). However, cell lines from two patients with CM without DN had normal post-UV plasmid MF. Although not specific for CM patients, of 27 cell lines with elevated post-UV plasmid MF, only 8 were from donors who did not have CM + DN or DN (19 of 24 versus 8 of 28; P = 0.0003). This study indicates that post-UV plasmid hypermutability is a laboratory marker for members of melanoma-prone families and suggests that patients with familial CM have a defective mechanism for handling UV-induced DNA damage.     

Virus-induced cell death in plants expressing the mammalian 2',5' oligoadenylate system

The major components of the 2-5A system, responsible for the mammalian interferon-induced antiviral response, are the 2',5' oligoadenylate synthetase (2-5Aase) and 2',5' oligoadenylate (2-5A) dependent ribonuclease (RNase L). Transgenic tobacco plants expressing these two enzyme activities were produced by crossing the transgenic plants expressing RNase L with those expressing 2-5Aase. The double transgenic plants showed complete resistance against cucumber mosaic virus (CMV), infection with necrotic spots only forming on the virus-inoculated leaf. On the other hand, although plants inoculated with potato virus Y (PVY) formed necrotic spots on the inoculated leaf and virus amplification could not be detected, all plants died within 20 days of inoculation. The transgenic tobacco plants expressing either 2-5Aase or RNase L activity showed typical disease symptoms with CMV- or PVY-inoculation. These results suggest that the introduced 2-5A system is activated in tobacco cells by dsRNA, the replicating intermediates of RNA viruses, leading to death of the host cells, which has not been observed in mammalian cells.     

Up-regulation of CIR1/CROC1 expression upon cell immortalization and in tumor-derived human cell lines

Inactivation of 5-HT1A and [3H]5-HT binding sites by N-Ethoxycarbonyl-2-ethoxy-1, 2-dihydroquinoline (EEDQ) was studied in regions of rat brain. After exposure to EEDQ (4 mg/kg body wt.) for 7 days, it is observed that the density of 5-HT1 receptor sites was decreased by nearly 20% in both cortex and hippocampus. The decrease, however, in 5-HT1A sites was more significant (70%) in both the regions. The affinity of [3H]5-HT to 5-HT1 sites was decreased significantly in both cortex and hippocampus after exposure to EEDQ, without affecting the Kd of 5-HT1A sites. Displacement studies suggested that EEDQ has high affinity to 5-HT1 sites with a Ki of 42.9+/-2.4 nM. After exposure neither basal nor 5-HT stimulated adenylyl cyclase activity was changed in cortex. The results of this study suggest that EEDQ decreases the density of 5-HT1 and 5-HT1A receptor sites but does not cause functional downregulation of these sites in rat brain.     

Regulation of germ cell death in mammalian gonads

A large number of primordial germ cells (PGCs), as well as spermatogonia, undergo programmed cell death or apoptosis in the physiological context. In this process, environmental, cytoplasmic and nuclear factors are involved. Bcl-2 and its related molecules are known as general regulators of cell death, and some are important for survival of PGCs and spermatogonia. Steel factor, a ligand for c-Kit, also supports growth and survival of these cells. In addition, bone morphogenetic protein (BMP)8B and Desert Hedgehog (Dhh), which are secreted proteins, and a nuclear factor, c-Myc, play a role in spermatocyte survival. This suggests that germ cell survival or death at each stage of differentiation is precisely controlled by specific signalling pathways which consist of a number of molecules.     

SPARC/osteonectin induces matrix metalloproteinase 2 activation in human breast cancer cell lines

Activation of the matrix metalloproteinase 2 (MMP-2) has been shown to play a major role in the proteolysis of extracellular matrix (ECM) associated with tumor invasion. Although the precise mechanism of this activation remains elusive, levels of the membrane type 1-MMP (MT1-MMP) at the cell surface and of the tissue inhibitor of MMP-2 (TIMP-2) appear to be two important determinants. Induction of MMP-2 activation in cells cultivated on collagen type I gels indicated that the ECM is important in the regulation of this process. In this study, we show that SPARC/osteonectin, a small ECM-associated matricellular glycoprotein, can induce MMP-2 activation in two invasive breast cancer cell lines (MDA-MB-231 and BT549) but not in a noninvasive counterpart (MCF-7), which lacks MT1-MMP. Using a set of peptides from different regions of SPARC, we found that peptide 1.1 (corresponding to the NH2-terminal region of the protein) contained the activity that induced MMP-2 activation. Despite the requirement for MT1-MMP, seen in MCF-7 cells transfected with MT1-MMP, the activation of MMP-2 by SPARC peptide 1.1 was not associated with increased steady-state levels of MT1-MMP mRNA or protein in either MT1-MMP-transfected MCF-7 cells or constitutively expressing MDA-MB-231 and BT549 cells. We did, however, detect decreased levels of TIMP-2 protein in the media of cells incubated with peptide 1.1 or recombinant SPARC; thus, the induction of MMP-2 activation by SPARC might be due in part to a diminution of TIMP-2 protein. We conclude that SPARC, and specifically its NH2-terminal domain, regulates the activation of MMP-2 at the cell surface and is therefore likely to contribute to the proteolytic pathways associated with tumor invasion.     

Identification of PTEN/MMAC1 alterations in uncultured melanomas and melanoma cell lines

A novel tumor suppressor gene, PTEN/MMAC1, has been recently shown to be mutated in gliomas, breast, prostate, kidney cancers and melanomas. Loss-of-heterozygosity studies in melanoma have suggested the presence of at least one chromosome 10q locus lost early in tumor progression. In this study, we screened 45 melanoma cell lines and 17 paired uncultured metastatic melanoma and peripheral blood specimens for PTEN/ MMAC1 alterations using PCR-SSCP and direct sequencing. We found nine melanoma cell lines with homozygous deletions (five with intragenic loss) and four cell lines with mutations (one nonsense and one frameshift; two intronic); from among our uncultured melanoma specimens, we found one tumor with a somatic 17 bp duplication in exon 7 leading to a premature stop codon and one tumor with a possible homozygous deletion. Furthermore, we have identified a novel intragenic polymorphism within intron 4 of PTEN/MMAC1. Taken together, these data suggest that PTEN/MMAC1 may be a chromosome 10q tumor suppressor important in melanoma tumor formation or progression.     

Alterations in cell signaling and related effector functions in T lymphocytes in burn/trauma/septic injuries

Conventional mitral valve replacement (MVR) for patients with chronic mitral regurgitation (MR) is usually associated with decrease in left ventricular (LV) ejection fraction (EF). This study investigated the effect of preoperative LV size on LV performance and examined loading conditions before and after conventional MVR. Echocardiographic study was performed on 13 and 9 patients with LV end-systolic dimension of less than 26 mm/m2 (group A) or greater than 26 mm/m2 (group B), respectively. Postoperatively, the LV end-diastolic dimension and EF decreased significantly in both groups. There was a decrease in end-systolic wall stress after MVR. Preoperative LV forward flow estimated by the normalized aortic peak velocity increased significantly in both groups after surgery. The decrease in EF after MVR is not the result of increased systolic loading, and LV performance may not decrease after conventional MVR. Preoperative echocardiographic evaluation can provide important prognostic information in patients with MR undergoing MVR.