Human Fibrosarcoma Cell Line HT1080 Research Articles

Internalization of Near-Infrared Fluorescently Labeled Activatable Cell-Penetrating Peptide and of Proteins into Human Fibrosarcoma Cell Line HT-1080.

The internalization of near-infrared fluorescently labeled cargos into living cells and tissues allows a highly sensitive detection without interference from skin, porphins or other fluorescent cell and tissue compounds. In this study, the uptake of labeled bovine serum albumin and an antibody, into fibrosarcoma (HT-1080) cells was triggered by the formation of non-covalent complexes with different cell-penetrating peptides; uptake efficiency and intracellular localization were determined. To improve selectivity of internalization into tumor cells, a fluorescent activatable cell-penetrating peptide (ACPP) was synthesized and functionally characterized. This 25-mer peptide was designed to be activatable by Matrix-Metallo-Proteases (MMPs). Its uptake selectivity was estimated using cells with different MMP activities.

A peptide functionalized poly(ethylene glycol) (PEG) hydrogel for investigating the influence of biochemical and biophysical matrix properties on tumor cell migration.

To address the challenges associated with defined control over matrix properties in 3D cell culture systems, we employed a peptide functionalized poly(ethylene glycol) (PEG) hydrogel matrix in which mechanical modulus and adhesive properties were tuned. An HT-1080 human fibrosarcoma cell line was chosen as a model for probing matrix influences on tumor cell migration using the PEG hydrogel platform. HT-1080 speed varied with a complex dependence on both matrix modulus and Cys-Arg-Gly-Asp-Ser (CRGDS) adhesion ligand concentration, with regimes in which motility increased, decreased, or was minimally altered being observed. We further investigated cell motility by forming matrix interfaces that mimic aspects of tissue boundaries that might be encountered during invasion by taking advantage of the spatial control of the thiol-ene photochemistry to form patterned regions of low and high cross-linking densities. HT-1080s in 100 Pa regions of patterned PEG hydrogels tended to reverse direction or aggregate at the interface when they encountered a 360 Pa boundary. In contrast, HT-1080s were apparently unimpeded when migrating from the stiff to the soft regions of PEG peptide hydrogels, which may indicate that cells are capable of "reverse durotaxis" within at least some matrix regimes. Taken together, our results identified matrix regimes in which HT-1080 motility was both positively and negatively influenced by cell adhesion or matrix modulus.

Inhibitory effects of p-dodecylaminophenol on the invasiveness of human fibrosarcoma cell line HT1080

Cancer is a major cause of death, and the development of new anticancer drugs is urgently needed. Invasion and metastasis are the primary causes of death due to cancer rather than growth of the primary tumor. In the current study, we examined the anti-invasive effects of p-dodecylaminophenol (1), which was developed based on N-(4-hydroxyphenyl)retinamide (2), a synthetic amide of all-trans-retinoic acid (3). In HT1080 cells 1 inhibited growth, induced apoptosis and arrested the cell cycle in S phase in a dose-dependent manner. In addition, 1 significantly suppressed cell invasion, and the activity and mRNA expression of matrix metalloproteinase-9 (MMP-9). Furthermore, the expression of the reversion-inducing cysteine-rich protein with Kazal motifs (RECK), which is a negative regulator of MMP-9, was increased by treatment with 1. These results suggest that 1 could be an effective anti-cancer agent that suppresses cell growth through apoptosis induction and cell cycle arrest, which also inhibits cell invasion by decreasing MMP-9 expression due to an increase in RECK. Compound 1 might be useful clinically as a new and potent anticancer agent that could overcome adverse side effects of the retinoids.

CD133+ subpopulation of the HT1080 human fibrosarcoma cell line exhibits cancer stem-like characteristics

The cancer stem cell (CSC) theory holds that a minority population within tumors possesses stem cell properties of self-renewal and multilineage differentiation capacity and provides the initiating cells from which tumors are derived and sustained. However, verifying the existence of these CSCs has been a significant challenge. The CD133 antigen is a pentaspan membrane glycoprotein proposed to be a CSC marker for cancer-initiating subpopulations in the brain, colon and various other tissues. Here, CD133+ cells were obtained and characterized from the HT1080 cell line to determine the utility of this marker for isolating CSCs from human fibrosarcoma cells. In this study, CD133+ cells were separated from HT1080 cells using magnetic beads and characterized for their proliferation rate and resistance to chemotherapeutic drugs, cisplatin and doxorubicin, by MTS assay. Relative expression of tumor-associated genes Sox2, Oct3/4, Nanog, c-Myc, Bmi-1 and ABCG2 was measured by real-time polymerase chain reaction (PCR). Clonal sphere formation and the ability of CD133+ cells to initiate tumors in BALB/c nude mice was also evaluated. We found that CD133+ cells showed a high proliferation rate, increased resistance to chemotherapy drugs and overexpression of tumor-associated genes compared with these features in CD133- cells. Additionally, CD133+ cells were able to form spherical clusters in serum-free medium with high clonogenic efficiency, indicating a significantly greater tumor-initiating potential when compared with CD133- cells. These findings indicate that CD133+ cells identified within the HT1080 human fibrosarcoma cell line possess many CSC properties and may facilitate the development of improved therapies for fibrosarcoma.

Anti-metastatic activity of biologically synthesized gold nanoparticles on human fibrosarcoma cell line HT-1080

Plants are exploited as a potential source for the large-scale production of noble gold nanoparticles in the recent years owing to their various potential applications in nanobiotechnology and nanomedicine. The present work describes green biosynthetic procedures for the production of gold nanoparticles for the first time by using an aqueous extract of the Dysosma pleiantha rhizome. The biosynthesized gold nanoparticles were confirmed and characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results revealed that aqueous extract of D. pleiantha rhizome has potential to reduce chloroauric ions into gold nanoparticles and the synthesized gold nanoparticles were showed spherical in shape with an average of 127nm. Further, we investigated the anti-metastatic activity of biosynthesized gold nanoparticles against human fibrosarcoma cancer cell line HT-1080. The results showed that the biosynthesized gold nanoparticles were non-toxic to cell proliferation and, also it can inhibit the chemo-attractant cell migration of human fibrosarcoma cancer cell line HT-1080 by interfering the actin polymerization pathway. Thus, the usage of gold nanoparticles biosynthesized from D. pleiantha rhizome can be used as a potential candidate in the drug and gene delivery to metastatic cancer.

Regulated Expressions of MMP-2, -9 by Diterpenoids from Euphorbia formosana Hayata

Two new abietane type diterpenoids, namely seco-helioscopinolide (1) and 3β,7β-dihydroxy-ent-abieta-8,13-diene-12,16-olide (2) were isolated from the aerial parts of Euphorbia formosana Hayata together with helioscopinolide A (3), helioscopinolide B (4), helioscopinolide C (5) and ent-(5β,8α,9β,10α,12α)-12-hydroxyatis-16-ene-3,14-dione (6). The structures of compounds 1−6 were elucidated by analyzing their spectroscopic data and comparison with the literature. Further biological tests by gelatin zymographic analysis revealed that 3−5 significantly up-regulated the expressions and activation of MMP-2 and -9 in human fibrosarcoma cell line HT1080.

A novel role of Rho-kinase in the regulation of ligand-induced phosphorylated EGFR endocytosis via the early/late endocytic pathway in human fibrosarcoma cells

The small GTPase RhoA and its downstream effectors, the Rho-associated kinase (Rho-kinase) family, are known to regulate cell morphology, motility, and tumor progression via the regulation of actin cytoskeleton rearrangement. In the present study, we evaluated the role of Rho-kinase in the intracellular endocytic trafficking of ligand-induced phosphorylated epidermal growth factor receptor (pEGFR). We investigated the time course of the internalization fate of EGF-induced pEGFR via the early/late endocytic pathway in human fibrosarcoma cell line HT1080 cells using Y-27632, a selective Rho-kinase inhibitor. We found, using confocal immunofluorescence microscopy and Western blot analysis, a large accumulation of pEGFR in the nuclei of HT1080 cells. In contrast, we observed decreased amounts of the pEGFR-positive staining in the nuclei along with an accumulation of cytosolic pEGFR staining when the cells were incubated for 15-30min in the presence of Y-27632, implying that an aberrant endocytic trafficking mechanism of pEGFR occurs in HT1080 cells whereby pEGFR might be selectively translocated into the nucleus. Moreover, we demonstrated that after 15-min of stimulation with Texas Red-EGF, increasing numbers of pEGFR-positive staining that had colocalized with Texas Red-EGF-positive punctate staining were seen in the cytoplasm of HT1080 cells but after 30-min of stimulation, most of this staining had disappeared from the cytoplasm and a large accumulation of pEGFR-positive staining appeared in the nucleus. Thus, nuclear accumulation of pEGFR appears to occur in an EGF-dependent manner. In contrast, such nuclear pEGFR-positive staining was not seen in the Y-27632-treated cells. Furthermore, silencing of RhoA or Rho-kinases I/II by sequence specific siRNAs considerably inhibited the EGF-dependent nuclear accumulation of pEGFR. Collectively, these results provide the first evidence that Rho-kinase signaling pathway plays a suppressive role in the intracellular vesicle trafficking of pEGFR via the endocytic pathway and that an increased Rho-kinase activity leads to the attenuation of the normal endocytic vesicular traffic of pEGFR via the early/late endocytic pathway, instead causing pEGFR to be trafficked out of the endocytic vesicles into the nucleus.

μ-Slide Chemotaxis: A new chamber for long-term chemotaxis studies

BackgroundEffective tools for measurement of chemotaxis are desirable since cell migration towards given stimuli plays a crucial role in tumour metastasis, angiogenesis, inflammation, and wound healing. As for now, the Boyden chamber assay is the longstanding "gold-standard" for in vitro chemotaxis measurements. However, support for live cell microscopy is weak, concentration gradients are rather steep and poorly defined, and chemotaxis cannot be distinguished from migration in a single experiment.ResultsHere, we describe a novel all-in-one chamber system for long-term analysis of chemotaxis in vitro that improves upon many of the shortcomings of the Boyden chamber assay. This chemotaxis chamber was developed to provide high quality microscopy, linear concentration gradients, support for long-term assays, and observation of slowly migrating cells via video microscopy. AlexaFluor 488 dye was used to demonstrate the establishment, shape and time development of linear chemical gradients. Human fibrosarcoma cell line HT1080 and freshly isolated human umbilical vein endothelial cells (HUVEC) were used to assess chemotaxis towards 10% fetal calf serum (FCS) and FaDu cells' supernatant. Time-lapse video microscopy was conducted for 48 hours, and cell tracking and analysis was performed using ImageJ plugins. The results disclosed a linear steady-state gradient that was reached after approximately 8 hours and remained stable for at least 48 hours. Both cell types were chemotactically active and cell movement as well as cell-to-cell interaction was assessable.ConclusionsCompared to the Boyden chamber assay, this innovative system allows for the generation of a stable gradient for a much longer time period as well as for the tracking of cell locomotion along this gradient and over long distances. Finally, random migration can be distinguished from primed and directed migration along chemotactic gradients in the same experiment, a feature, which can be qualified via cell morphology imaging.

Abstract 1500: A novel nutrient mixture exhibits antitumor activity in human fibrosarcoma cell line HT-1080

Abstract Introduction: Fibrosarcoma, an aggressive and highly metastatic cancer of connective tissue, is generally associated with poor prognosis. Cancer mortality usually results from tumor invasion of local tissue and metastasis to vital organs. We investigated the effect of a specific nutrient mixture (PB) of quercetin, cruciferex, curcumin, green tea extract and resveratrol on human fibrosarcoma cell line HT-1080 for viability, MMP expression, invasion, apoptosis and morphology. Material and Methods: Human fibrosarcoma cell line HT-1080 (ATCC) was cultured in DEM media, supplemented with 10% FBS and antibiotics in 24-well tissue plates. At near confluence, cells were treated with PB at 0, 10, 25, 50, 75 and 100 mcg/mL, in triplicate at each dose. Cells were also treated with PMA (100 ng/mL) for MMP-9 induction. Cell proliferation was assayed by MTT assay, MMP by zymography, invasion through Matrigel, apoptosis using green caspase detection, and morphology by H&E staining. Results: PB inhibited proliferation of human fibrosarcoma cells HT-1080 by 50% at 10 mcg/mL, 60% at 25 mcg/mL and 80% at 50-100 mcg/mL, and inhibited the secretion of both MMP-2 and MMP-9 in a dose-dependent manner, with total inhibition at 50 mcg/mL concentration. Invasion through Matrigel was inhibited 100% at 25 mcg/mL PB. PB also induced apoptosis in a dose- dependent fashion. H&E staining showed slight morphological changes at higher concentrations. Conclusion: These results suggest that PB is a potential therapeutic agent for fibrosarcoma, with potent anti-metastatic activity, because it inhibited fibrosarcoma cell proliferation, MMP-2 and -9 expression, invasion through Matrigel and apoptosis, important parameters for cancer prevention. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1500. doi:10.1158/1538-7445.AM2011-1500

Abstract 1383: Impact of carbamylation and glycation of collagen type I on HT1080 cell migration

Abstract Carbamylation and glycation are well known as nonenzymatic posttranslational modifications that occur throughout the lifespan of proteins in vivo. Due to its longevity, collagen type I, largely present in connective tissues, becomes a prominent target for such modifications. Protein carbamylation and glycation have been implicated in normal aging and in a number of pathologies like diabetes, renal diseases and cancer. In addition, recent studies suggest a possible link between increased cancer risk and diabetes or end-stage renal disease. Here, we investigate the impact of carbamylation and glycation of collagen on the proliferation and migration capacities of the highly invasive human fibrosarcoma cell line HT1080. For this purpose, collagen type I extracted from rat tail tendons was used for in vitro carbamylation with cyanate or glycation with ribose. The amount of carbamylation and glycation was evaluated respectively via HPLC and spectrofluorimetry, and only the maximum levels of carbamylated and glycated collagens were considered. Tumor cell behavior was then evaluated on coatings of native, carbamylated or glycated collagen. Our results show that the proliferation of HT1080 cells on modified collagens did not differ from that on native form after 1, 2 and 3 days of culture. Concerning tumor cell adhesion, the glycated collagen delayed the adhesion time of seeded cells whereas the carbamylated form had no effect. Using time-lapse videomicroscopy, the migration ability of HT1080 was studied by quantifying single cell speed. Only, the glycated collagen strongly inhibited cell speed migration. We next investigated the effect of these collagen modifications on the organization of actin and vinculin, two proteins involved in cell locomotion. On glycated collagen, cells revealed a dramatic loss of actin stress fibers where disorganized F-actin was principally localized at the rim of the cell. Disturbance of actin integrity was accompanied with a disorganization of vinculin that was also localized at the cell periphery. On the other hand, the cells on carbamylated collagen maintained a fully organized actin network. The impact on the focal adhesion kinase (FAK), which plays a crucial role in focal adhesion formation, was also evaluated. Only glycated collagen induced a significant inhibition of the expression level of FAK, whereas both collagen modifications provoke a differential inhibition of its phosphorylation state that is mainly taking place with glycation. In conclusion, only glycation is demonstrated as an important factor affecting tumor cell migration. This impact has to be certainly considered in order to better understand the link between diabetes, aging and cancer incidence. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1383. doi:10.1158/1538-7445.AM2011-1383

Epigenetic regulation of proMMP-1 expression in the HT1080 human fibrosarcoma cell line

The matrix metalloproteinase (MMP) family members play an important role in various physiological and pathological processes. Although MMP-1 (collagenase-1) has been shown to be involved in tumor invasiveness, the regulation of its expression is still not fully elucidated and could implicate epigenetic mechanisms. The aim of this study was to analyze the effects of the Histone Deacetylase Inhibitor (HDI) trichostatin A (TSA) and the inhibitor of DNA methylation 5-aza-2'-deoxycytidine (5-azadC) on the proMMP-1 expression in the human HT1080 fibrosarcoma cell line. Real-time RT-PCR revealed that 5-azadC or 5-azadC + TSA but not TSA alone, despite global histone H4 hyperacetylation, increased proMMP-1 mRNA levels. This transcription activation was correlated with chromatin decondensation determined by nuclear texture image analysis technique. Western blot analysis of cell culture conditioned media revealed a significant increase in proMMP-1 secretion after 5-azadC or 5-azadC + TSA treatment compared to untreated cells. These results suggested that epigenetic mechanisms could be involved in proMMP-1 gene expression including chromatin supra-organization changes. Indeed, although the proMMP-1 gene promoter does not appear to contain CpG islands, its expression can be induced by the demethylating agent 5-azadC. Further experiments revealed that inhibition of protein neosynthesis by cycloheximide decreased 5-azadC-induced proMMP-1 mRNA, suggesting that epigenetically regulated intermediate molecules could be involved in proMMP-1 expression regulation in these cells.

Differential utilization of NF-kappaB RELA and RELB in response to extracellular versus intracellular polyIC stimulation in HT1080 cells

BackgroundPattern recognition receptors (PRRs) for double-stranded RNA (dsRNA) are components of innate immunity that recognize the presence of viral infection and initiate efficient defense mechanisms. In addition to previously well-characterized signaling pathways that are mediated by PKR and TLR3, new intracellular dsRNA sensors, that are members of CARD and DExD/H box helicase family, have been identified. However, the molecular mechanisms involved in the signaling pathways mediated by these new dsRNA sensors have not been extensively characterized.ResultsHere, we studied an intracellular dsRNA pathway in the human fibrosarcoma cell line HT1080, which is distinct from the TLR3-mediated extracellular dsRNA pathway. Particularly, the NF-kB subunits RELA and RELB were differentially utilized by these two dsRNA signaling pathways. In TLR3-mediated dsRNA signaling, siRNA knock-down studies suggested a limited role for RELA on regulation of interferon beta and other cytokines whereas RELB appeared to have a negative regulatory role. By contrast, intracellular dsRNA signaling was dependent on RELA, but not RELB.ConclusionsOur study suggests that extracellular and intracellular dsRNA signaling pathways may utilize different NF-kB members, and particularly the differential utilization of RELB may be a key mechanism for powerful inductions of NF-kB regulated genes in the intracellular dsRNA signaling pathway.

Negative Regulation of TGFβ Signaling by the Kinase LKB1 and the Scaffolding Protein LIP1

Signal transduction by the Smad pathway elicits critical biological responses to many extracellular polypeptide factors, including TGFβ and bone morphogenetic protein. Regulation of Smad signaling imparts several cytoplasmic and nuclear mechanisms, some of which entail protein phosphorylation. Previous work established a protein complex between Smad4 and the scaffolding protein LKB1-interacting protein 1 (LIP1). LKB1 is a well studied tumor suppressor kinase that regulates cell growth and polarity. Here, we analyzed the LKB1-LIP1 and the Smad4-LIP1 protein complexes and found that LIP1 can self-oligomerize. We further demonstrate that LKB1 is capable of phosphorylating Smad4 on Thr77 of its DNA-binding domain. LKB1 inhibits Smad4 from binding to either TGFβ- or bone morphogenetic protein-specific promoter sequences, which correlates with the negative regulatory effect LKB1 exerts on Smad4-dependent transcription. Accordingly, LKB1 negatively regulates TGFβ gene responses and epithelial-mesenchymal transition. Thus, LKB1 and LIP1 provide negative control of TGFβ signaling.

Inhibitory effect of caffeic acid on cancer cell proliferation by oxidative mechanism in human HT-1080 fibrosarcoma cell line

Caffeic acid (3,4-dihydroxy cinnamic acid) (CA) is naturally found in fruits, vegetables, olive oil, and coffee. This study was undertaken to evaluate the anticancer effect of caffeic acid on HT-1080 human fibrosarcoma cell line. The antiproliferative effect of caffeic acid was determined by MTT assay, and the oxidative stress was determined by lipid peroxidation, changes in the enzymatic, and non-enzymatic antioxidant status. To understand the mode of antiproliferative effect of CA, the authors observed intracellular ROS levels by DCFH-DA method, mitochondrial membrane potential alterations by Rh-123 staining, oxidative DNA damage by comet assay, and apoptotic morphological changes by AO/EtBr-staining method. The results show that caffeic acid enhances lipid peroxidative markers such as TBARS, CD, and LHP in HT-1080 cell line. Caffeic acid enhances the ROS levels, which is evidenced by the increased DCF fluorescence. Further, caffeic acid treatment altered the mitochondrial membrane potential in HT-1080 cells. Similarly, the authors observed increased oxidative DNA damage (% Tail DNA, % Tail length, Tail moment, and olive tail moment), and apoptotic morphological changes in caffeic acid-treated groups. These data suggest that caffeic acid exhibits potent anticancer effect in HT-1080 cell line, and that it may be used as an anticancer agent.

Canthin-6-one Alkaloids and a Tirucallanoid from Eurycoma longifolia and Their Cytotoxic Activity against a Human HT-1080 Fibrosarcoma Cell Line

Phytochemical investigation of the stems of Eurycoma longifolia Jack led to the isolation of two new canthin-6-one alkaloids, 4,9-dimethoxycanthin-6-one (1) and 10-hydroxy-11-methoxycanthin-6-one (2), and a new tirucallane-type triterpenoid, 23,24,25-trihydroxytirucall-7-en-3,6-dione (3), along with 37 known compounds. Among these, an oxasqualenoid (4) was isolated as a natural product for the first time. The structures of the isolates were elucidated by spectroscopic and mass spectrometric means. All the isolates were evaluated for their cytotoxic activity against a HT-1080 human fibrosarcoma cell line. Among them, 9,10-dimethoxycanthin-6-one (14, IC50 = 5.0 microM), 10-hydroxy-9-methoxycanthin-6-one (15, IC50 = 7.2 microM), dihydroniloticin (18, IC50 = 8.2 microM), and 14-deacetyleurylene (34, IC50 = 3.2 microM) displayed stronger activity than the positive control 5-FU (IC50 = 9.2 microM).

Quassinoids from Eurycoma longifolia

Ten new structurally diverse quassinoids (1-10) and 14 known compounds were isolated from the stems of Eurycoma longifolia. The new compounds were two eurycomanone-type C(20) quassinoids (1, 2), one klaineanone-type C(20) quassinoid (3), one C(19) quassinoid (4) with a 1,2-seco-1-nor-6(5-->10)-abeo-picrasan-2,5-olide skeleton, and six eurycomalactone-type C(19) quassinoids (5-10). Compounds 5 and 6 both possessed a 3,4-epoxy group observed for the first time in eurycomalactones. Compound 1 had an alpha-oriented OH group at C-14 that had not been reported previously in eurycomanone-type quassinoids. All of the isolates were evaluated for cytotoxicity toward the highly metastatic HT-1080 human fibrosarcoma cell line, and compounds 11, 23, and 24 showed potent cytotoxicity (IC(50) values 0.93-1.1 microM).

VAMP3, syntaxin-13 and SNAP23 are involved in secretion of matrix metalloproteinases, degradation of the extracellular matrix and cell invasion

Cellular remodeling of the extracellular matrix (ECM), an essential component of many physiological and pathological processes, is dependent on the trafficking and secretion of matrix metalloproteinases (MMPs). Soluble NSF attachment protein receptor (SNARE)-mediated membrane traffic has documented roles in cell-ECM interactions and the present study specifically examines SNARE function in the trafficking of MMPs during ECM degradation. Using the invasive human fibrosarcoma cell line HT-1080, we demonstrate that a plasma membrane SNARE, SNAP23, and an endosomal v-SNARE, VAMP3 (also known as cellubrevin), partly colocalize with MMP2 and MMP9, and that inhibition of these SNAREs using dominant-negative SNARE mutants impaired secretion of the MMPs. Inhibition of VAMP3, SNAP23 or syntaxin-13 using dominant-negative SNARES, RNA interference or tetanus toxin impaired trafficking of membrane type 1 MMP to the cell surface. Consistent with these observations, we found that blocking the function of these SNAREs reduced the ability of HT-1080 cells to degrade a gelatin substrate in situ and impaired invasion of HT-1080 cells in vitro. The results reveal the importance of VAMP3, syntaxin-13 and SNAP23 in the trafficking of MMP during degradation of ECM substrates and subsequent cellular invasion.

Autotaxin Promotes the Expression of Matrix Metalloproteinase-3 via Activation of the MAPK Cascade in Human Fibrosarcoma HT-1080 Cells

Autotaxin (ATX) is an approximately 125-kDa transmembrane protein that is considered to be a tumor progression factor based on its lysophospholipase D activity. Here, we report that lysophosphatidic acid produced by ATX promotes the secretion of matrix metalloproteinase-3 (MMP3) from the human fibrosarcoma cell line HT-1080. The c-Jun N-terminal kinases (JNKs) and c-Jun of HT-1080 cells were rapidly phosphorylated after ATX treatment. A specific JNK inhibitor also exhibited this activation of signaling molecules and MMP3 expression. The present results suggest a novel function of ATX in promoting MMP3 production via the mitogen-activated protein kinase cascade, thereby stimulating tumor cell invasiveness.

Aberrant expression of BAFF receptor, a member of the tumor necrosis factor receptor family, in malignant cells of nonhematopoietic origins

The acquired capability of evading apoptosis is one of the prerequisites for cancer development, and NF-kappaB plays a critical role by inducing anti-apoptotic molecules. In this study, we firstly carried out an expression-cloning approach to isolate the responsible molecules in the NF-kappaB activation pathway with the defective mutant cell line, COS-A717. This cell line shows reduced constitutive basal activity of NF-kappaB as compared with the parental COS cells. We successfully isolated genes with compensating activity for the pathway, and one gene encoded B-cell activating factor receptor (BAFF-R). However, a Northern blot analysis revealed that the BAFF-R expression is not only limited to cells of B cell origin, but also is found in those with nonhematopoietic origins. In the human fibrosarcoma cell line HT1080, an immunohistochemical analysis revealed that the expression of BAFF-R is not on the cell surface, but in the cytoplasm. The expression of BAFF was also detected, and the reduction of endogenous BAFF or BAFF-R by siRNA decreased the basal NF-kappaB activity. Lastly, from clinicopathological specimens, the associated expression of BAFF-R and BAFF was demonstrated in osteosarcoma. We propose that an aberrant BAFF/BAFF-R-dependent autocrine mechanism may play a role in the development of certain types of cancer cells.

Structural analysis of the glycosylation of gene-activated erythropoietin (epoetin delta, Dynepo)

Recently, a novel recombinant human erythropoietin (epoetin delta, Dynepo) has been marketed in the European Union for the treatment of chronic kidney disease, cancer patients receiving chemotherapy, and so forth. Epoetin delta is engineered in cultures of the human fibrosarcoma cell line HT-1080 by homologous recombination and “gene activation.” Unlike recombinant erythropoietins produced in other mammalian cells, epoetin delta is supposed to have a human-type glycosylation profile. However, the isoelectric focusing profile of epoetin delta differs from that of endogenous erythropoietin (both urinary and plasmatic). In this work, structural and quantitative analysis of the O- and N-glycans of epoetin delta was performed and compared with glycosylation from recombinant erythropoietin produced in Chinese hamster ovary (CHO) cells. From the comparison, significant differences in the sialylation of O-glycans were found. Furthermore, the N-glycan analysis indicated a lower heterogeneity from epoetin delta when compared with its CHO homologue, being predominantly tetraantennary without N-acetyllactosamine repeats in the former. The sialic acid characterization revealed the absence of N-glycolylneuraminic acid. The overall sugar profiles of both glycoproteins appeared to be significantly different and could be useful for maintaining pharmaceutical quality control, detecting the misuse of erythropoietin in sports, and establishing new avenues to link glycosylation with biological activity of glycoproteins.