Differences in polyamine availability and insertion into fibronectins released from normal and transformed cells.
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ABSTRACT:
SUBMITTER: Roch AM
PROVIDER: S-EPMC1154199 | biostudies-other | 1983 Jan
REPOSITORIES: biostudies-other
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Project description:1. The activity of diamine oxidase (EC 1.4.3.6) in normal rat kidney cells and in normal rat kidney cells transformed by avian sarcoma virus (B77 strain) growing in tissue culture varies with the stage of growth. There is an initial stimulation of activity by 24h after seeding, followed by a steep decline during exponential growth (48-72h). Enzyme activity decreases even further as the cells reach saturation density (confluence) after 4 days in culture when the activity in normal rat kidney cells is twice as high as that in transformed cells. 2. Differences of about the same order of magnitude are observed between transformed human cells HeLa, HEp2 (a human epithelioid carcinoma) and normal human fibroblasts, in chicken cells between normal myeloblasts and leukaemic myeloblasts, and in rats between biopsy material from normal mammary tissue and 9,10-dimethylbenz[a]anthracene-induced mammary tumours. 3. Polyamine oxidase activity also varies with the growth of transformed rat kidney cells, but shows no significant variation with the growth of normal rat kidney cells between 24 and 96h after seeding. The activity in cells at confluence is from 3- to 5-fold lower in the transformed than in the normal rat kidney cells. 4. A similar 5-10-fold decrease in activity has been found in 9,10-dimethylbenz[a]anthracene-induced mammary tumours in rats and in human oesophageal tumours. 5. Possible reasons for these observations and the contribution of these two enzymes to cellular putrescine concentrations are discussed.
| S-EPMC1186366 | biostudies-other
Project description:Transformed baby-hamster-kidney cells contain higher intracellular concentrations of polyamines than do normal cells. The difference is greater in high-density confluent cultures. Transformed cells incorporate exogenous putrescine into the cells at a faster rate than do normal cells. They also show a marked increase in the rate of spermine biosynthesis compared with normal cells. Transformed cells grown to high cell densities released about 10% of their polyamines into the culture medium in a non-specific manner. In contrast, normal cells, under the same culture conditions, release up to 50% of their intracellular polyamines into the medium almost exclusively as free or conjugated spermidine. The elevated levels of polyamines found in transformed cells therefore appear to be the result of altered transport of polyamines across the cell membrane and of increased rates of biosynthesis.
| S-EPMC1158176 | biostudies-other
Project description:Tumor promotion is strongly associated with inflammation and increased polyamine levels. Our understanding of relevant mechanisms responsible for arsenic-induced cancer remains limited. Previous studies suggest that arsenic targets and dysregulates stem cell populations that remain dormant in the skin until promoted to be recruited out of the bulge stem cell region, thus giving rise to skin tumors. In this study, we explored a possible mechanism by which increased keratinocyte polyamine biosynthesis promotes tumorsphere formation and invasiveness of arsenic-transformed HaCaT keratinocytes (As-HaCaT). Unlike parental HaCaT cells, As-HaCaT cells were tumorigenic in athymic nude mice, and the CD45negative epithelial tumor cells had enriched expression of Toll-Like Receptor 4 (TLR4), CD34 and CXCR4 as did As-HaCaT tumorsphere cultures compared to As-HaCaT monolayer cultures. Ornithine decarboxylase (ODC) overexpressing keratinocytes (Ker/ODC) release increased levels of the alarmin high mobility group box 1 (HMGB1). Ker/ODC conditioned medium (CM) stimulated As-HaCaT but not parental HaCaT tumorsphere formation, and this was inhibited by glycyrrhizin, an inhibitor of HMGB1, and by TAK242, an inhibitor of the HMGB1 receptor TLR4. Compared to parental HaCaT cells, As-HaCaT cells demonstrated greater invasiveness across a Matrigel-coated filter using either fibroblast CM or SDF-1α as chemoattractants. Addition of Ker/ODC CM or HMGB1 dramatically increased As-HaCaT invasiveness. Glycyrrhizin and TAK242 inhibited this Ker/ODC CM-stimulated invasion of As-HaCaT cells but not HaCaT cells. These results show that polyamine-dependent release of HMGB1 promotes the expansion of stem cell-like subpopulations in arsenic-transformed keratinocytes while also increasing their invasiveness, suggesting that polyamines may be a potential therapeutic target for the prevention and treatment of arsenic-initiated skin cancers.
| S-EPMC6735862 | biostudies-literature
Project description:IntroductionCholine is an essential human nutrient that is particular important for proliferating cells, and altered choline metabolism has been associated with cancer transformation. Yet, the various metabolic fates of choline in proliferating cells have not been investigated systematically.ObjectivesThis study aims to map the metabolic products of choline in normal and cancerous proliferating cells.MethodsWe performed 13C-choline tracing followed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis of metabolic products in normal and in vitro-transformed (tumor-forming) epithelial cells, and also in tumor-derived cancer cell lines. Selected metabolites were quantified by internal standards.ResultsUntargeted analysis revealed 121 LCMS peaks that were 13C-labeled from choline, including various phospholipid species, but also previously unknown products such as monomethyl- and dimethyl-ethanolamines. Interestingly, we observed formation of betaine from choline specifically in tumor-derived cells. Expression of choline dehydrogenase (CHDH), which catalyzes the first step of betaine synthesis, correlated with betaine synthesis across the cell lines studied. RNAi silencing of CHDH did not affect cell proliferation, although we observed an increased fraction of G2M phase cells with some RNAi sequences, suggesting that CHDH and its product betaine may play a role in cell cycle progression. Betaine cell concentration was around 10 µM, arguing against an osmotic function, and was not used as a methyl donor. The function of betaine in these tumor-derived cells is presently unknown.ConclusionThis study identifies novel metabolites of choline in cancer and normal cell lines, and reveals altered choline metabolism in cancer cells.
| S-EPMC7701132 | biostudies-literature
Project description:Transplanted adult bone marrow-derived cells (BMDCs) have been shown to adopt the phenotype and function of several nonhematopoietic cell lineages and promote tumorigenesis. Beyond its cancer enhancing potential, cell fusion has recently emerged as an explanation of how BMDCs regenerate diseased heptocytes, contribute to Purkinje neurons and skeletal and cardiac muscle cells, and participate in skin and heart regeneration. Although bone marrow-derived epithelial cells also have been observed in the intestine, fusion as a mechanism has not been investigated. Here, we show that transplanted BMDCs fuse with both normal and neoplastic intestinal epithelium. Long-term repopulation by donor-derived cells was detected in all principal intestinal epithelial lineages including enterocytes, goblet cells, Paneth cells, and enteroendocrine cells, suggesting that the fusion partners of the BMDCs are long-lived intestinal progenitors or stem cells. Fusion of BMDCs with neoplastic epithelium did not result in tumor initiation. Our findings suggest an unexpected role for BMDCs in both regeneration and tumorigenesis of the intestine.
| S-EPMC1435365 | biostudies-literature
Project description:This study examines the chromatin structure encompassing replication origins in transformed and normal cells. Analysis of the global levels of histone H3 acetylated at K9&14 (open chromatin) and histone H3 trimethylated at K9 (closed chromatin) revealed a higher ratio of open to closed chromatin in the transformed cells. Also, the trithorax and polycomb group proteins, Brg-1 and Bmi-1, respectively, were overexpressed and more abundantly bound to chromatin in the transformed cells. Quantitative comparative analyses of episomal and in situ chromosomal replication origin activity as well as chromatin immunoprecipitation (ChIP) assays, using specific antibodies targeting members of the pre-replication complex (pre-RC) as well as open/closed chromatin markers encompassing both episomal and chromosomal origins, revealed that episomal origins had similar levels of in vivo activity, nascent DNA abundance, pre-RC protein association, and elevated open chromatin structure at the origin in both cell types. In contrast, the chromosomal origins corresponding to 20mer1, 20mer2, and c-myc displayed a 2- to 3-fold higher activity and pre-RC protein abundance as well as higher ratios of open to closed chromatin and of Brg-1 to Bmi-1 in the transformed cells, whereas the origin associated with the housekeeping lamin B2 gene exhibited similar levels of activity, pre-RC protein abundance, and higher ratios of open to closed chromatin and of Brg-1 to Bmi-1 in both cell types. Nucleosomal positioning analysis, using an MNase-Southern blot assay, showed that all the origin regions examined were situated within regions of inconsistently positioned nucleosomes, with the nucleosomes being spaced farther apart from each other prior to the onset of S phase in both cell types. Overall, the results indicate that cellular transformation is associated with differential epigenetic regulation, whereby chromatin structure is more open, rendering replication origins more accessible to initiator proteins, thus allowing increased origin activity.
| S-EPMC3463923 | biostudies-literature
Project description:Ovarian carcinoma arises from the ovarian surface epithelium, which undergoes phenotypic changes characteristic of müllerian epithelium during the first stages of tumorigenesis. The variant isoform of the hepatocyte nuclear factor 1 (vHNF1) is a transcription factor involved in the development of tissues derived from the müllerian duct. Here, we show that vHNF1 knockdown in two ovarian carcinoma cell lines, SKOV3 and IGROV1, leads to reduced E-cadherin (E-cadh) expression and decreased proliferation rate. Accordingly, SKOV3 cells ectopically expressing a dominant-negative (DN) vHNF1 mutant undergo an epithelial-mesenchymal-like transition, acquiring a spindle-like morphology, loss of E-cadh, and disrupted cell-cell contacts. Gene expression profiling of DNvHNF1 cells on the basis of a newly compiled list of epithelial-mesenchymal transition-related genes revealed a correlation between vHNF1 loss-of-function and acquisition of the mesenchymal phenotype. Indeed, phenotypic changes were associated with increased Slug transcription and functionality. Accordingly, vHNF1-transfected immortalized ovarian surface epithelial cells showed down-regulation of Snail and Slug transcripts. In DNvHNF1-transfected SKOV3 cells, growth rate decreased, and in vHNF1-transfected immortalized ovarian surface epithelial cells, growth rate increased. By immunohistochemistry, we found a strong association of vHNF1 with E-cadh in clear cell and in a subset of serous carcinomas, data that could potentially contribute in distinguishing different types of ovarian tumors. Our results may help in understanding the biology of ovarian carcinoma, identifying early detection markers, and opening potential avenues for therapeutic intervention.
| S-EPMC2586698 | biostudies-literature
Project description:Cancer stem cells (CSCs) may be responsible for tumour dormancy, relapse and the eventual death of most cancer patients. In addition, these cells are usually resistant to cytotoxic conditions. However, very little is known about the biology behind this resistance to therapeutics. Here we investigated stem-cell death in the digestive system of adult Drosophila melanogaster. We found that knockdown of the coat protein complex I (COPI)-Arf79F (also known as Arf1) complex selectively killed normal and transformed stem cells through necrosis, by attenuating the lipolysis pathway, but spared differentiated cells. The dying stem cells were engulfed by neighbouring differentiated cells through a draper-myoblast city-Rac1-basket (also known as JNK)-dependent autophagy pathway. Furthermore, Arf1 inhibitors reduced CSCs in human cancer cell lines. Thus, normal or cancer stem cells may rely primarily on lipid reserves for energy, in such a way that blocking lipolysis starves them to death. This finding may lead to new therapies that could help to eliminate CSCs in human cancers.
| S-EPMC7798135 | biostudies-literature
Project description:At the initial stage of carcinogenesis, transformation occurs in a single cell within an epithelial sheet. However, it remains unknown what happens at the boundary between normal and transformed cells. Using Madin-Darby canine kidney (MDCK) cells transformed with temperature-sensitive v-Src, we have examined the interface between normal and Src-transformed epithelial cells. We show that Src-transformed cells are apically extruded when surrounded by normal cells, but not when Src cells alone are cultured, suggesting that apical extrusion occurs in a cell-context-dependent manner. We also observe apical extrusion of Src-transformed cells in the enveloping layer of zebrafish gastrula embryos. When Src-transformed MDCK cells are surrounded by normal MDCK cells, myosin-II and focal adhesion kinase (FAK) are activated in Src cells, which further activate downstream mitogen-activated protein kinase (MAPK). Importantly, activation of these signalling pathways depends on the presence of surrounding normal cells and plays a crucial role in apical extrusion of Src cells. Collectively, these results indicate that interaction with surrounding normal epithelial cells influences the signalling pathways and behaviour of Src-transformed cells.
| S-EPMC2954245 | biostudies-literature
Project description:BackgroundCancer and normal stem cells (SCs) share proliferative properties of self-renewal and expression of key transcription factors (TFs). Despite similar TF identities, the functional role of specific TFs responsible for retaining SC state has yet to be examined in cancer.Methodology/principal findingsHere, we compare the role of Oct4 and Nanog, two-core pluripotent TFs, in transformed (t-hPSCs), and normal human pluripotent stem cells (hPSCs). Unlike normal SCs, self-renewal and survival of t-hPSCs were found to be independent of Oct4. In contrast, t-hPSCs exhibit hypersensitivity to reduction in Nanog and demonstrate complete loss of self-renewal coupled with apoptosis. Dual and sequential knockdown of Oct4 and Nanog revealed that sensitivity of t-hPSCs to Nanog was Oct4 dependent.Conclusions/significanceOur study indicates a bifurcation for the role of two-core SC and cancer related TFs in self-renewal and survival processes. We suggest that the divergent roles of these TFs establish a paradigm to develop novel therapeutics towards selective destruction of aggressive tumors harboring cancer stem cells (CSCs) with similar molecular signatures.
| S-EPMC2778551 | biostudies-literature