Showing papers on "Cell culture published in 1997"
TL;DR: Cleavage of laminin-5 by MMP2 and the resulting activation of the Ln-5 cryptic site may provide new targets for modulation of tumor cell invasion and tissue remodeling.
Abstract: Structural changes in the extracellular matrix are necessary for cell migration during tissue remodeling and tumor invasion. Specific cleavage of laminin-5 (Ln-5) by matrix metalloprotease-2 (MMP2) was shown to induce migration of breast epithelial cells. MMP2 cleaved the Ln-5 gamma2 subunit at residue 587, exposing a putative cryptic promigratory site on Ln-5 that triggers cell motility. This altered form of Ln-5 is found in tumors and in tissues undergoing remodeling, but not in quiescent tissues. Cleavage of Ln-5 by MMP2 and the resulting activation of the Ln-5 cryptic site may provide new targets for modulation of tumor cell invasion and tissue remodeling.
1,251 citations
TL;DR: Evidence is reported for the presence of ALT in a subset of tumor-derived cell lines and tumors, presumably via one or more novel telomere-lengthening mechanisms that the authors refer to as ALT (alternative lengthening of telomeres)
Abstract: The gradual loss of DNA from the ends of telomeres has been implicated in the control of cellular proliferative potential1–3. Telomerase is an enzyme that restores telomeric DNA sequences4, and expression of its activity was thought to be essential for the immortalization of human cells, both in vitro and in tumor progression in vivo5. Telomerase activity has been detected in 50–100% of tumors of different types, but not in most normal adult somatic tissues6,7. It has also been detected in about 70% of human cell lines immortalized in vitro and in all tumor-derived cell lines examined to date7. It has previously been shown that in vitro immortalized telomerase-negative cell lines acquire very long and heterogeneous telomeres in association with immortalization8–11 presumably via one or more novel telomere-lengthening mechanisms that we refer to as ALT (alternative lengthening of telomeres)11. Here we report evidence for the presence of ALT in a subset of tumor-derived cell lines and tumors. The maintenance of telomeres by a mechanism other than telomerase, even in a minority of cancers, has major implications for therapeutic uses of telomerase inhibitors.
1,242 citations
TL;DR: Kidney, heart and spleen tissue obtained from domestic pigs contained multiple copies of integrated PERV genomes and expressed viral RNA, which could rescue a Moloney retroviral vector and acquired resistance to lysis by human complement.
Abstract: The possible use of pig organs and tissues as xenografts in humans is actively being considered in biomedical research. We therefore examined whether pig endogenous retrovirus (PERV) genomes can be infectiously transmitted to human cells in culture. Two pig kidney cell lines spontaneously produce C-type retrovirus particles. Cell-free retrovirus produced by the PK-15 kidney cell line (PERV-PK) infected pig, mink and human kidney 293 cell lines and co-cultivation of X-irradiated PK-15 cells with human cells resulted in a broader range of human cell infection, including human diploid fibroblasts and B- and T-cell lines. Kidney, heart and spleen tissue obtained from domestic pigs contained multiple copies of integrated PERV genomes and expressed viral RNA. Upon passage in human cells PERV-PK could rescue a Moloney retroviral vector and acquired resistance to lysis by human complement.
1,122 citations
TL;DR: A role for this TNF-related ligand in the regulation of the T cell-dependent immune response is suggested.
1,114 citations
TL;DR: Findings show that HIF-1 activation occurs in hypoxic regions of tumors and demonstrate a major influence on gene expression, tumor angiogenesis, and growth.
Abstract: Recent studies of tissue culture cells have defined a widespread system of oxygen-regulated gene expression based on the activation of a heterodimeric transcription factor termed hypoxia-inducible factor-1 (HIF-1). To determine whether the HIF-1 transcriptional response is activated within solid tumors and to define the consequences, we have studied tumor xenografts of a set of hepatoma (Hepa-1) cells that are wild type (wt), deficient (c4), and revertant (Rc4) for an obligatory component of the HIF-1 heterodimer, HIF-1β. Because HIF-1β is also essential for the xenobiotic response (in which it is termed the aryl hydrocarbon receptor nuclear translocator), we also studied c31 cells, which have a different defect in the xenobiotic response and form the HIF-1 complex normally. Two genes that show different degrees of HIF-1-dependent hypoxia-inducible expression in cell culture were selected for analysis—the glucose transporter, GLUT3, and vascular endothelial growth factor (VEGF). In situ hybridization showed intense focal induction of gene expression in tumors derived from wt, Rc4, and c31 cells, which was reduced (VEGF) or not seen (GLUT3) in those derived from c4 cells. In association with these changes, tumors of c4 cells had reduced vascularity and grew more slowly. These findings show that HIF-1 activation occurs in hypoxic regions of tumors and demonstrate a major influence on gene expression, tumor angiogenesis, and growth.
1,068 citations
TL;DR: It is suggested that an increased LDH-A level is required for the growth of a transformed spheroid cell mass, which has a hypoxic internal microenvironment and is necessary for c-Myc-mediated transformation.
Abstract: Cancer cells are able to overproduce lactic acid aerobically, whereas normal cells undergo anaerobic glycolysis only when deprived of oxygen. Tumor aerobic glycolysis was recognized about seven decades ago; however, its molecular basis has remained elusive. The lactate dehydrogenase-A gene (LDH-A), whose product participates in normal anaerobic glycolysis and is frequently increased in human cancers, was identified as a c-Myc-responsive gene. Stably transfected Rat1a fibroblasts that overexpress LDH-A alone or those transformed by c-Myc overproduce lactic acid. LDH-A overexpression is required for c-Myc-mediated transformation because lowering its level through antisense LDH-A expression reduces soft agar clonogenicity of c-Myc-transformed Rat1a fibroblasts, c-Myc-transformed human lymphoblastoid cells, and Burkitt lymphoma cells. Although antisense expression of LDH-A did not affect the growth of c-Myc-transformed fibroblasts adherent to culture dishes under normoxic conditions, the growth of these adherent cells in hypoxia was reduced. These observations suggest that an increased LDH-A level is required for the growth of a transformed spheroid cell mass, which has a hypoxic internal microenvironment. Our studies have linked c-Myc to the induction of LDH-A, whose expression increases lactate production and is necessary for c-Myc-mediated transformation.
930 citations
Journal Article•
TL;DR: The analysis revealed that cells with mutant p53 sequence tended to exhibit less growth inhibition in this screen than the wild-type p53 cell lines when treated with the majority of clinically used anticancer agents: including DNA cross-linking agents, antimetabolites, and topoisomerase I and II inhibitors.
Abstract: In the present study, we report the characterization of the p53 tumor suppressor pathway in the 60 cell lines of the National Cancer Institute (NCI) anticancer drug screen, as well as correlations between the integrity of this pathway and the growth-inhibitory potency of 123 anticancer agents in this screen. Assessment of p53 status in these lines was achieved through complete p53 cDNA sequencing, measurement of basal p53 protein levels and functional assessment of ( a ) transcriptional activity of p53 cDNA from each line in a yeast assay, ( b ) γ-ray-induced G 1 phase cell cycle arrest, and ( c ) γ-ray-induced expression of CIP1/WAF1, GADD45 , and MDM2 mRNA. Our investigations revealed that p53 gene mutations were common in the NCI cell screen lines: 39 of 58 cell lines analyzed contained a mutant p53 sequence. cDNA derived from almost all of the mutant p53 cell lines failed to transcriptionally activate a reporter gene in yeast, and the majority of mutant p53 lines studied expressed elevated basal levels of the mutant p53 protein. In contrast to most of the wild-type p53 -containing lines, cells containing mutant p53 sequence were also deficient in γ-ray induction of CIP1/WAF1, GADD45 , and MDM2 mRNA and the ability to arrest in G 1 following γ-irradiation. Taken together, these assessments provided indications of the integrity of the p53 pathway in the 60 cell lines of the NCI cell screen. These individual p53 assessments were subsequently used to probe a database of growth-inhibitory potency for 123 “standard agents,” which included the majority of clinically approved anticancer drugs. These 123 agents have been tested against these lines on multiple occasions, and a proposed mechanism of drug action had previously been assigned to each agent. Our analysis revealed that cells with mutant p53 sequence tended to exhibit less growth inhibition in this screen than the wild-type p53 cell lines when treated with the majority of clinically used anticancer agents: including DNA cross-linking agents, antimetabolites, and topoisomerase I and II inhibitors. Similar correlations were uncovered when we probed this database using most of the other indices of p53 status we assessed in the lines. Interestingly, a class of agents that differed in this respect was the antimitotic agents. Growth-inhibitory activity of these agents tended, in this assay, to be independent of p53 status. Our characterization of the p53 pathway in the NCI cell screen lines should prove useful to researchers investigating fundamental aspects of p53 biology and pharmacology. This information also allows for the large-scale analysis of the more than 60,000 compounds tested against these lines for novel agents that might exploit defective p53 function as a means of preferential toxicity.
900 citations
TL;DR: Since ER inhibits the constitutive as well as inducible activation function of NF-kappaB in a dose-dependent manner, it is proposed that breast cancers that lack functional ER overexpress NF- kappaB-regulated genes.
Abstract: Breast cancers often progress from a hormone-dependent, nonmetastatic, antiestrogen-sensitive phenotype to a hormone-independent, antiestrogen- and chemotherapy-resistant phenotype with highly invasive and metastatic growth properties. This progression is usually accompanied by altered function of the estrogen receptor (ER) or outgrowth of ER-negative cancer cells. To understand the molecular mechanisms responsible for metastatic growth of ER-negative breast cancers, the activities of the transcription factor NF-kappaB (which modulates the expression of genes involved in cell proliferation, differentiation, apoptosis, and metastasis) were compared in ER-positive (MCF-7 and T47-D) and ER-negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines. NF-kappaB, which is usually maintained in an inactive state by protein-protein interaction with inhibitor IkappaBs, was found to be constitutively active in ER-negative breast cancer cell lines. Constitutive DNA binding of NF-kappaB was also observed with extracts from ER-negative, poorly differentiated primary breast tumors. Progression of the rat mammary carcinoma cell line RM22-F5 from an ER-positive, nonmalignant phenotype (E phenotype) to an ER-negative, malignant phenotype (F phenotype) was also accompanied by constitutive activation of NF-kappaB. Analysis of individual subunits of NF-kappaB revealed that all ER-negative cell lines, including RM22-F5 cells of F phenotype, contain a unique 37-kDa protein which is antigenically related to the RelA subunit. Cell-type-specific differences in IkappaB alpha, -beta, and -gamma were also observed. In transient-transfection experiments, constitutive activity of an NF-kappaB-dependent promoter was observed in MDA-MB-231 and RM22-F5 cells of F phenotype, and this activity was efficiently repressed by cotransfected ER. Since ER inhibits the constitutive as well as inducible activation function of NF-kappaB in a dose-dependent manner, we propose that breast cancers that lack functional ER overexpress NF-kappaB-regulated genes. Furthermore, since recent data indicate that NF-kappaB protects cells from tumor necrosis factor alpha-, ionizing radiation-, and chemotherapeutic agent daunorubicin-mediated apoptosis, our results provide an explanation for chemotherapeutic resistance in ER-negative breast cancers.
859 citations
TL;DR: At the checkpoint between the prereplicative phase of growth and the phase of chromosome replication, cells lacking p21 failed to arrest the cell cycle in response to DNA damage, but their apoptotic response and genomic stability were unaltered.
Abstract: Most somatic cells die after a finite number of cell divisions, a phenomenon described as senescence. The p21 CIP1/WAF1 gene encodes an inhibitor of cyclin-dependent kinases. Inactivation of p21 by two sequential rounds of targeted homologous recombination was sufficient to bypass senescence in normal diploid human fibroblasts. At the checkpoint between the prereplicative phase of growth and the phase of chromosome replication, cells lacking p21 failed to arrest the cell cycle in response to DNA damage, but their apoptotic response and genomic stability were unaltered. These results establish the feasibility of using gene targeting for genetic studies of normal human cells.
827 citations
TL;DR: Evidence is provided that there may be a direct link between inhibition of intestinal cancer growth and selective inhibition of the COX-2 pathway.
Abstract: A considerable amount of evidence collected from several different experimental systems indicates that cyclooxygenase-2 (COX-2) may play a role in colorectal tumorigenesis. Large epidemiologic studies have shown a 40-50% reduction in mortality from colorectal cancer in persons taking aspirin or other nonsteroidal antiinflammatory drugs on a regular basis. One property shared by all of these drugs is their ability to inhibit COX, a key enzyme in the conversion of arachidonic acid to prostaglandins. Two isoforms of COX have been characterized, COX-1 and COX-2. COX-2 is expressed at high levels in intestinal tumors in humans and rodents. In this study, we selected two transformed human colon cancer cell lines for studies on the role of COX-2 in intestinal tumorigenesis. We evaluated HCA-7 cells which express high levels of COX-2 protein constitutively and HCT-116 cells which lack COX-2 protein. Treatment of nude mice implanted with HCA-7 cells with a selective COX-2 inhibitor (SC-58125), reduced tumor formation by 85-90%. SC-58125 also inhibited colony formation of cultured HCA-7 cells. Conversely, SC-58125 had no effect on HCT-116 implants in nude mice or colony formation in culture. Here we provide evidence that there may be a direct link between inhibition of intestinal cancer growth and selective inhibition of the COX-2 pathway.
751 citations
TL;DR: Data demonstrate that hypoxia induces HO-1 expression in animal tissues and cell cultures and implicate HIF-1 in this response.
TL;DR: Results identify residues β270 and β364 as important modulators of paclitaxel’s interaction with tubulin as well as acquired mutations in the M40 isotype at nucleotide 810 (T → G; Phe270 → Val) in 1A9PTX10 cells and nucleotide 1092 (G → A; Ala364 → Thr) in1A 9PTX22 cells.
TL;DR: The results suggest that somatic cells competent to form embryos and early globular somatic embryos share a highly specific signal transduction chain with the zygotic embryo from shortly after fertilization to theEarly globular embryo.
Abstract: The first somatic single cells of carrot hypocotyl explants having the competence to form embryos in the presence of 2,4-dichlorophenoxyacetic acid (2,4-D) were identified using semi-automatic cell tracking. These competent cells are present as a small subpopulation of enlarged and vacuolated cells derived from cytoplasm-rich and rapidly proliferating non-embryogenic cells that originate from the provascular elements of the hypocotyl. A search for marker genes to monitor the transition of somatic into competent and embryogenic cells in established suspension cell cultures resulted in the identification of a gene transiently expressed in a small subpopulation of the same enlarged single cells that are formed during the initiation of the embryogenic cultures from hypocotyl explants. The predicted amino acid sequence and in vitro kinase assays show that this gene encodes a leucine-rich repeat containing receptor-like kinase protein, designated Somatic Embryogenesis Receptor-like Kinase (SERK). Somatic embryos formed from cells expressing a SERK promoter-luciferase reporter gene. During somatic embryogenesis, SERK expression ceased after the globular stage. In plants, SERK mRNA could only be detected transiently in the zygotic embryo up to the early globular stage but not in unpollinated flowers nor in any other plant tissue. These results suggest that somatic cells competent to form embryos and early globular somatic embryos share a highly specific signal transduction chain with the zygotic embryo from shortly after fertilization to the early globular embryo.
TL;DR: The development and isolation of a cell line that replicates human hepatitis B virus under conditions that can be regulated with tetracycline is reported, and this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.
Abstract: We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.
TL;DR: Two Ad vectors which contain modifications to the Ad fiber coat protein that redirect virus binding to either alpha(v) integrin or heparan sulfate cellular receptors demonstrate the feasibility of tissue-specific receptor targeting in cells which express low levels of Ad fiber receptor.
Abstract: Alteration of the natural tropism of adenovirus (Ad) will permit gene transfer into specific cell types and thereby greatly broaden the scope of target diseases that can be treated by using Ad. We have constructed two Ad vectors which contain modifications to the Ad fiber coat protein that redirect virus binding to either alpha(v) integrin [AdZ.F(RGD)] or heparan sulfate [AdZ.F(pK7)] cellular receptors. These vectors were constructed by a novel method involving E4 rescue of an E4-deficient Ad with a transfer vector containing both the E4 region and the modified fiber gene. AdZ.F(RGD) increased gene delivery to endothelial and smooth muscle cells expressing alpha(v) integrins. Likewise, AdZ.F(pK7) increased transduction 5- to 500-fold in multiple cell types lacking high levels of Ad fiber receptor, including macrophage, endothelial, smooth muscle, fibroblast, and T cells. In addition, AdZ.F(pK7) significantly increased gene transfer in vivo to vascular smooth muscle cells of the porcine iliac artery following balloon angioplasty. These vectors may therefore be useful in gene therapy for vascular restenosis or for targeting endothelial cells in tumors. Although binding to the fiber receptor still occurs with these vectors, they demonstrate the feasibility of tissue-specific receptor targeting in cells which express low levels of Ad fiber receptor.
TL;DR: It is concluded that a functional IL-18 receptor component is IL-1Rrp, the ligand of which was unknown to date when expressed in COS-1 cells.
Journal Article•
TL;DR: The c-myc null cell lines reported here are a new experimental system in which to investigate the importance of putative c-Myc target genes and to identify novel downstream genes involved in cell cycle progression and apoptosis.
Abstract: Rat fibroblast cell lines with targeted disruptions of both c-myc gene copies were constructed. Although c-myc null cells are viable, their growth is significantly impaired. The absence of detectable N-myc or L-myc expression indicates that Myc function is not absolutely essential for cell viability. The c-myc null phenotype is stable and can be reverted by introduction of a c-myc transgene. Exponentially growing c-myc null cells have the same cell size, rRNA, and total protein content as their c-myc +1+ parents, but the rates of RNA and protein accumulation as well as protein degradation are reduced. Both the G1 and G2 phases of the cell cycle are significantly lengthened, whereas the duration of S phase is unaffected. This is the first direct demonstration of a requirement for c-myc in G2. The G0-+S transition is synchronous, but S-phase entry is significantly delayed. The c-myc null cell lines reported here are a new experimental system in which to investigate the importance of putative c-Myc target genes and to identify novel downstream genes involved in cell cycle progression and apoptosis.
Journal Article•
TL;DR: These findings establish for the first time the cell type- and differentiation-specific patterns of expression of an interleukin-1beta converting enzyme/CED-3 (Caspase-3) family protease.
Abstract: The in vivo patterns of CPP32 (Caspase-3) gene expression were determined using an immunohistochemical approach and paraffin-embedded normal human tissues. A rabbit polyclonal antiserum was generated against recombinant human CPP32 protein and shown to be specific by immunoblot analysis of various human tissues and cell lines. CPP32 immunoreactivity was selectively found in certain cell types and was typically present within the cytosol, although occasional cells also contained nuclear immunostaining. CPP32 immunostaining was easily detected, for example, in epidermal keratinocyes, cartilage chondrocytes, bone osteocytes, heart myocardiocytes, vascular smooth muscle cells, bronchial epithelium, hepatocytes, thymocytes, plasma cells, renal tubule epithelium, spermatogonia, prostatic secretory epithelial cells, uterine endometrium and myometrium, mammary ductal epithelial cells, and the gastrointestinal epithelium of the stomach, intestine, and colon. In contrast, little or no CPP32 immunoreactivity was observed in endothelial cells, alveolar pneumocytes, kidney glomeruli, mammary myoepithelial cells, Schwann cells, and most types of brain and spinal cord neurons. Consistent with a role for CPP32 in apoptotic cell death, clear differences in the relative intensity of CPP32 immunostaining were noted in some shorter-lived types of cells compared to longer-lived, including (a) germinal center (high) versus mantle zone (low) B lymphocytes within the secondary follicles of lymph nodes, spleen, and tonsils; (b) mature neutrophils (high) versus myeloid progenitor cells (low) in bone marrow; (c) corpus luteal cells (high) versus follicular granulosa cells (low) in the ovary; and (d) prostate secretory epithelial cells (high) versus basal cells (low). These findings establish for the first time the cell type- and differentiation-specific patterns of expression of an interleukin-1beta converting enzyme/CED-3 (Caspase) family protease.
TL;DR: In Ras-transformed MDCK cells, expression of Tiam1 or RacV12 restored E-cadherin-mediated adhesion, resulting in phenotypic reversion and loss of invasiveness, suggesting an invasion-suppressor role for Tiam 1 and Rac in epithelial cells.
Abstract: Tiam1 encodes an exchange factor for the Rho-like guanosine triphosphatase Rac. Both Tiam1 and activated RacV12 promote invasiveness of T lymphoma cells. In epithelial Madin-Darby canine kidney (MDCK) cells, Tiam1 localized to adherens junctions. Ectopic expression of Tiam1 or RacV12 inhibited hepatocyte growth factor-induced scattering by increasing E-cadherin-mediated cell-cell adhesion accompanied by actin polymerization at cell-cell contacts. In Ras-transformed MDCK cells, expression of Tiam1 or RacV12 restored E-cadherin-mediated adhesion, resulting in phenotypic reversion and loss of invasiveness. These data suggest an invasion-suppressor role for Tiam1 and Rac in epithelial cells.
TL;DR: The results indicate that the conditions within solid tumors are mutagenic and suggest that a fundamental mechanism of tumor progression in vivo is genetic instability induced by the tumor microenvironment.
Abstract: The tumor microenvironment is characterized by regions of fluctuating hypoxia, low pH, and nutrient deprivation. To determine the genetic consequences of growth under these conditions, we used a tumorigenic cell line carrying a recoverable, chromosomally based lambda phage shuttle vector designed to report mutations without the need for genetic selection of mutant cells. The cells were grown in parallel either in culture or as tumors in nude mice. The frequency of mutations arising in cells within the tumors was found to be 5-fold higher than that in otherwise identical cells grown in culture. A distinct pattern of mutation was also seen, with significantly more deletions and transversions in the tumors than in the cell cultures. Furthermore, exposure of the cultured cells to hypoxia produced an elevated mutation frequency and a mutation pattern similar to that seen in the tumors. These results indicate that the conditions within solid tumors are mutagenic and suggest that a fundamental mechanism of tumor progression in vivo is genetic instability induced by the tumor microenvironment.
TL;DR: GILZ expression selectively protects T cells from apoptosis induced by treatment with anti-CD3 monoclonal antibody but not by treatment of other apoptotic stimuli, and correlates with inhibition of Fas and Fas ligand expression.
TL;DR: Cell culture experiments reveal that cerebellar cells lacking PrPc are more sensitive to oxidative stress and undergo cell death more readily than wild-type cells, and in vivo studies show that the activity of Cu/Zn superoxide dismutase is reduced in Prnp gene-ablated mice.
TL;DR: Transcription of c-myc in plasma cells, which are terminally differentiated B cells, is repressed by plasmacytoma repressor factor, a component of the Blimp-1 program of terminal B cell differentiation.
Abstract: Transcription of c-myc in plasma cells, which are terminally differentiated B cells, is repressed by plasmacytoma repressor factor This factor was identified as Blimp-1, known for its ability to induce B cell differentiation Blimp-1 repressed c-myc promoter activity in a binding site-dependent manner Treatment of BCL1 lymphoma cells with interleukin-2 (IL-2) plus IL-5 induced Blimp-1 and caused a subsequent decline in c-Myc protein Ectopic expression of Blimp-1 in Abelson-transformed precursor B cells repressed endogenous c-Myc and caused apoptosis; Blimp-1-induced death was partially overcome by ectopic expression of c-Myc Thus, repression of c-myc is a component of the Blimp-1 program of terminal B cell differentiation
TL;DR: The RWPE-1 cells, which show many normal cell characteristics, and the malignantRWPE-2 cells, provide useful cell culture models for studies on prostate growth regulation and carcinogenesis.
Abstract: Prostate cancer and benign tumors of the prostate are the two most common neoplastic diseases in men in the United States, however, research on their causes and treatment has been slow because of the difficulty in obtaining fresh samples of human tissue and a lack of well characterized cell lines which exhibit growth and differentiation characteristics of normal prostatic epithelium. Non-neoplastic adult human prostatic epithelial cells from a white male donor were immortalized with human papillomavirus 18 which resulted in the establishment of the RWPE-1 cell line. Cells from the RWPE-1 cell line were further transformed by v-Ki-ras to establish the RWPE-2 cell line. The objectives of this study were to: (1) establish the prostatic epithelial origin and androgen responsiveness of RWPE-1 and RWPE-2 cell lines; (2) examine their response to growth factors; and (3) establish the malignant characteristics of the RWPE-2 cell line. Immunoperoxidase staining showed that both RWPE-1 and RWPE-2 cells express cytokeratins 8 and 18, which are characteristic of luminal prostatic epithelial cells, but they also coexpress basal cell cytokeratins. These cell lines show growth stimulation and prostate specific antigen (PSA) and androgen receptor (AR) expression in response to the synthetic androgen mibolerone, which establishes their prostatic epithelial origin. Both cell lines also show a dose-dependent growth stimulation by EGF and bFGF and growth inhibition when exposed to TGF-beta, however, the transformed RWPE-2 cells are less responsive. RWPE-1 cells neither grow in agar nor form tumors when injected into nude mice with or without Matrigel. However, RWPE-2 cells form colonies in agar and tumors in nude mice. In the in vitro invasion assay, RWPE-1 cells are not invasive whereas RWPE-2 cells are invasive. Nuclear expression of p53 and Rb proteins was heterogeneous but detectable by immunostaining in both cell lines. The RWPE-1 cells, which show many normal cell characteristics, and the malignant RWPE-2 cells, provide useful cell culture models for studies on prostate growth regulation and carcinogenesis.
Journal Article•
TL;DR: Enforced expression of IL-8 rendered the melanoma cells highly tumorigenic and increased their metastatic potential as compared with parental and control transfected cells, suggesting thatIL-8 is involved in MMP-2 gene transcription.
Abstract: Expression of interleukin-8 (IL-8) by human melanoma cells correlates with their metastatic potential. Moreover, UV-B irradiation of primary cutaneous melanoma cells induces IL-8 mRNA and protein production and increases both tumor growth and metastasis in nude mice. Although IL-8 has been shown to be an angiogenic factor, the biological consequences of increased IL-8 production by melanoma cells and the role of IL-8 in the metastatic process remains unclear. The purpose of this study was to determine the role of IL-8 in tumor growth and metastasis of human melanoma cells. Nonmetastatic SB-2 melanoma cells with negligible levels of IL-8 were transfected with IL-8 cDNA and subsequently analyzed for changes in their tumorigenic and metastatic potential. Enforced expression of IL-8 rendered the melanoma cells highly tumorigenic and increased their metastatic potential as compared with parental and control transfected cells. The IL-8-transfected cells displayed up-regulation in M(r) 72,000 collagenase type IV (MMP-2) mRNA and collagenase activity and increased invasiveness through Matrigel-coated filters. Moreover, when the MMP-2 promoter was linked upstream of the chloramphenicol acetyltransferase (CAT) reporter gene, CAT activity was up-regulated in IL-8 but not in control transfected cells, suggesting that IL-8 is involved in MMP-2 gene transcription. Activation of type IV collagenase by IL-8 can enhance the invasion of host stroma by the tumor cells and increase angiogenesis and, hence, metastasis.
TL;DR: In this article, the effect of bisphosphonate treatment on cell number and cell cycle progression was examined using flow cytometry, and the ability of bisosphonates to induce apoptosis in human myeloma cell lines was determined on the basis of changes in nuclear morphology and of DNA fragmentation.
Abstract: Bisphosphonates are in widespread use to prevent bone resorption in a number of metabolic and tumour-induced bone diseases including multiple myeloma. Recent reports suggest that bisphosphonate treatment may be associated with an increase in patient survival, raising the possibility that these compounds may have a direct effect on the tumour cells. We have investigated whether the bisphosphonates clodronate, pamidronate and YM175 can directly affect the human myeloma cell lines U266-B1, JJN-3 and HS-Sultan in vitro. The effect of bisphosphonate treatment on cell number and cell cycle progression was examined using flow cytometry. The ability of bisphosphonates to induce apoptosis in human myeloma cell lines was determined on the basis of changes in nuclear morphology and of DNA fragmentation. Pamidronate and the more potent bisphosphonate. YM175, significantly decreased cell number (P < 0.001) in JJN-3 and HS-Sultan cells. YM175 also caused cells to arrest in the S-phase of the cell cycle in the JJN-3 cell line. Both pamidronate and YM175 also caused an increase in the proportion of cells with altered nuclear morphology (P < 0.05) and fragmented DNA, characteristic of apoptosis, in both JJN-3 and HS-Sultan cells. In contrast, clodronate had little effect on cell number and did not cause apoptosis at the concentrations examined. These data raise the possibility that some bisphosphonates could have direct anti-tumour effects on human myeloma cells in vivo.
TL;DR: NF-kappa B is a transcriptional regulator of IL-8 production, and its activation after bacterial infection may be an important defense response in gastrointestinal epithelial cells.
Journal Article•
TL;DR: It is suggested that defective cytotrophoblast differentiation/invasion can have significant consequences to the outcome of human pregnancy and that, by the time delivery becomes necessary, the defect is not reversed by removing the cells from the maternal environment.
Abstract: During human placental development, cytotrophoblast stem cells differentiate and invade the uterus. Simultaneously, the cells modulate their expression of several classes of stage-specific antigens that mark transitions in the differentiation process and play a role in either uterine invasion (integrin cell-extracellular matrix receptors and matrix metalloproteinase-9) or immune interactions (HLA-G). The pregnancy disease pre-eclampsia is associated with shallow cytotrophoblast invasion. Previously we showed, by immunofluorescence localization on placental tissue, that in pre-eclampsia invasive cytotrophoblasts fail to properly modulate their integrin repertoire. This finding suggests possible abnormalities in the differentiation pathway that leads to uterine invasion. Here we used a culture system that supports this differentiation process to compare the differentiative and invasive potential of cytotrophoblasts obtained from control (n = 8, 22 to 38 weeks) and pre-eclamptic (n = 9, 24 to 38 weeks) placentas. In culture, the cells from pre-eclamptic placentas failed to properly modulate alpha1 integrin and matrix metalloproteinase-9 expression at the protein and mRNA levels. Their invasive potential was also greatly reduced. Likewise, the cells failed to up-regulate HLA-G protein and mRNA expression. These results suggest that defective cytotrophoblast differentiation/invasion can have significant consequences to the outcome of human pregnancy (ie, development of pre-eclampsia) and that, by the time delivery becomes necessary, the defect is not reversed by removing the cells from the maternal environment.
TL;DR: The results support the notion that the metastatic behavior of lung cancer cells can be characterized with this in vitro system, and that the properties of these progressively invasive cancer Cells can be clonally studied.
Abstract: To better understand the mechanism(s) underlying lung cancer invasion and metastasis, a Transwell invasion chamber was used to select progressively more invasive cancer cell populations from a clonal cell line of human lung adenocarcinoma, CL1. Five sublines with progressive invasiveness, designated CL1-1, CL1-2, CL1-3, CL1-4, and CL1-5, were obtained through this in vitro selection process. Their invasive abilities through basement membrane matrix showed a 4- to 6-fold increase over that of the parental cells. Moreover, the sublines manifested an increase in their colony-forming ability on soft agar, tumorigenicity, and metastatic potency in severe combined immunodeficiency (SCID) mice. Examining the phenotypes of the cell lines revealed increased expression of 92 kD gelatinase and an increase in the cell population stained with anti-keratin-8 and -18 antibodies. Clonal isolation of anti-keratin-18-antibody-positive and -negative cell populations demonstrated a correlated enhancement of the invasiveness of these cells and their expression of keratin-18. These results support the notion that the metastatic behavior of lung cancer cells can be characterized with this in vitro system, and that the properties of these progressively invasive cancer cells can be clonally studied.
TL;DR: It is indicated that endocytosis can regulate the cell-surface expression of CXCR4 and that SDF-1–mediated down regulation of cell- surface coreceptor expression contributes to chemokine-mediated inhibition of HIV infection.
Abstract: The chemokine receptor CXCR4 is required, together with CD4, for entry by some isolates of HIV-1, particularly those that emerge late in infection. The use of CXCR4 by these viruses likely has profound effects on viral host range and correlates with the evolution of immunodeficiency. Stromal cell-derived factor-1 (SDF-1), the ligand for CXCR4, can inhibit infection by CXCR4-dependent viruses. To understand the mechanism of this inhibition, we used a monoclonal antibody that is specific for CXCR4 to analyze the effects of phorbol esters and SDF-1 on surface expression of CXCR4. On human T cell lines SupT1 and BC7, CXCR4 undergoes slow constitutive internalization (1.0% of the cell surface pool/min). Addition of phorbol esters increased this endocytosis rate >6-fold and reduced cell surface CXCR4 expression by 60 to 90% over 120 min. CXCR4 was internalized through coated pits and coated vesicles and subsequently localized in endosomal compartments from where it could recycle to the cell surface after removal of the phorbol ester. SDF-1 also induced the rapid down modulation (half time approximately 5 min) of CXCR4. Using mink lung epithelial cells expressing CXCR4 and a COOH-terminal deletion mutant of CXCR4, we found that an intact cytoplasmic COOH-terminal domain was required for both PMA and ligand-induced CXCR4 endocytosis. However, experiments using inhibitors of protein kinase C indicated that SDF-1 and phorbol esters trigger down modulation through different cellular mechanisms. SDF-1 inhibited HIV-1 infection of mink cells expressing CD4 and CXCR4. The inhibition of infection was less efficient for CXCR4 lacking the COOH-terminal domain, suggesting at least in part that SDF-1 inhibition of virus infection was mediated through ligand-induced internalization of CXCR4. Significantly, ligand induced internalization of CXCR4 but not CD4, suggesting that CXCR4 and CD4 do not normally physically interact on the cell surface. Together these studies indicate that endocytosis can regulate the cell-surface expression of CXCR4 and that SDF-1-mediated down regulation of cell-surface coreceptor expression contributes to chemokine-mediated inhibition of HIV infection.