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Local immunotherapy of spontaneous feline fibrosarcomas using recombinant poxviruses expressing interleukin 2 (IL2).

We tested the canarypox virus vector ALVAC and the genetically attenuated vaccinia virus vector NYVAC as vehicles for achieving local immunomodulation in domestic animals bearing spontaneous tumours. Following intratumoral administration of ALVAC-, or NYVAC-luciferase in dogs with melanoma, it was demonstrated that viral recombinants remained localized along the needle track, with no virus detectable in the periphery of the tumour. Given these distribution characteristics and their well-documented safety profile, ALVAC- or NYVAC-based recombinants expressing feline or human IL2, respectively, were administered to domestic cats, in order to prevent the recurrence of spontaneous fibrosarcomas. In the absence of immunotherapy, tumour recurrence was observed in 61% of animals within a 12-month follow-up period after treatment with surgery and iridium-based radiotherapy. In contrast, only 39 and 28% of cats receiving either NYVAC-human IL2 or ALVAC-feline IL2, respectively, exhibited tumour recurrences. Based on such results, and in the context of ongoing clinical studies conducted in humans, we discuss the utilization of ALVAC- or NYVAC-based recombinants as viable therapeutic modalities for local immunotherapy or therapeutic vaccination against cancer, both in humans and companion animals.

Animals↗

Counter-selection for over-expressed human CD44s in primary tumors versus lung metastases in a mouse fibrosarcoma model.

Human CD44 standard isoform cDNA (hCD44s) was transfected into sis-transformed Balb/c 3T3 cells and into ras-revertant IIIA4 cells (both tumorigenic but nonmetastatic). Transfectants were injected subcutaneously into athymic nude mice to elucidate the functional role of hCD44s over-expression in progression and metastasis. The transfectants (but not parental cells) were capable of lung micrometastasis and of binding exogenously-added hyaluronan. hCD44s protein expression was conserved in lung micrometastases suggesting that it may have been necessary for their formation. In contrast, no hCD44s protein was detected in large subcutaneous (s.c.) tumors but normal levels of murine CD44 were detected. A second round of tumor development, using these two tumor cell classes, demonstrated that hCD44s-nonexpressing s.c. tumor cells re-expressed it in lung micrometastases. Conversely, hCD44s-expressing lung micrometastatic cells, when injected into a second group of mice, downregulated hCD44s expression in order to grow sizable s.c. tumors. S.c. tumor cells still contained the hCD44s gene but its expression was inhibited by epigenetic mechanisms, one of which was shown to be methylation of the hCD44s gene. These studies demonstrate (a) opposing selective pressures on CD44s over-expression for s.c. tumor growth and for metastatic spread to the lung and (b) further credence for the significance of CD44 for metastatic spread of fibrosarcomas. Therefore, CD44s may be a critical component of the metastatic phenotype induced by specific oncogenes.

3T3 Cells↗

Ursolic acid-induced down-regulation of MMP-9 gene is mediated through the nuclear translocation of glucocorticoid receptor in HT1080 human fibrosarcoma cells.

We have previously reported that ursolic acid, a pentacyclic triterpene acid, inhibited the invasion of HT1080 human fibrosarcoma cells by reducing the expression of matrix metalloproteinase-9. Since the chemical structure of ursolic acid is very similar to that of dexamethasone, a synthetic glucocorticoid, we investigated whether ursolic acid acts through the glucocorticoid receptor. The expression of matrix metalloproteinase-9 is thought to be regulated similarly with matrix metalloproteinase-1 and matrix metalloproteinase-3 as containing common 2-O-tetradecanoylphorbol-acetate responsible region, where AP-1 proteins can bind. Dexamethasone has been studied to repress the 2-O-tetradecanoylphorbol-acetate-induced expression of matrix metalloproteinase-1 and matrix metalloproteinase-3 through a glucocorticoid receptor-mediated manner. In Northern blot analysis, we found that ursolic acid reduced the expression of matrix metalloproteinase-1 and matrix metalloproteinase-3 induced by 2-O-tetradecanoylphorbol-acetate. Similarly, ursolic acid down-regulated 2-O-tetradecanoylphorbol-acetate-induction of matrix metalloproteinase-9 gene in the same manner of dexamethasone. RU486, a potent glucocorticoid receptor antagonist, was used for identifying that ursolic acid-induced down-regulation of matrix metalloproteinase-9 expression is mediated by its binding to glucocorticoid receptor. The effect of ursolic acid on the matrix metalloproteinase-9 expression was blocked by RU486, suggesting that ursolic acid acts via a glucocorticoid receptor in the regulation of matrix metalloproteinase-9. Western blot analysis and immunocytochemistry showed that ursolic acid increased glucocorticoid receptor fraction in the nucleus, although it decreased the synthesis of glucocorticoid receptor mRNA. In addition, ursolic acid did not decrease the expression of c-jun and DNA-binding activity of AP-1 to its cognate sequences. Taken together, we suggest that ursolic acid may induce the repression of matrix metalloproteinase-9 by stimulating the nuclear translocation of glucocorticoid receptor, and the translocated glucocorticoid receptor probably down-modulating the trans-activating function of AP-1 to 2-O-tetradecanoylphorbol-acetate responsible element of matrix metalloproteinase-9 promoter region.

Binding Sites↗

Allele-specific inactivation of the alpha4 integrin gene expression in fibrosarcoma cell lines and relevance for spontaneous metastasis.

Deregulated expression of genes is found in cancer cells, which may affect malignant properties, but it is unclear whether such modulation occurs allele-specifically. This study shows that the gene coding alpha4 integrin, a cell adhesion molecule, underwent allelic inactivation in a series of heterozygous murine fibrosarcoma cell lines (MST lines) with different metastatic potentials. P4 cells expressed the alpha4 integrin gene from one allele at a level comparable to that of the primary MST1 tumor, whereas the descendent lines of P4 exhibited decreased expression of both alleles. No allelic loss of DNA was observed in these cells. Other four clones derived from P4 and five clones from a different tumor also showed such two-step inactivation. Intriguingly, the loss of expression was correlated with the acquisition of spontaneous, but not artificial, metastatic ability. This is consistent with the previous result of inverse relation between the expression of alpha4/beta1 integrin and the invasive potential of B16 melanoma cells. Analysis of DNA methylation and chromatin state of the alpha4 integrin gene failed to provide a clue to difference between the two alleles in the cell lines. These results suggest that the allelic inactivation is a process giving loss of function to one allele, although the mechanism is unclear.

Alleles↗

p53 induces angiogenesis-restricted dormancy in a mouse fibrosarcoma.

The p53 tumor-suppressor gene is inactivated in over 50% of all human cancers. In normal cells, p53 induces growth arrest and apoptosis in response to DNA damage. We show that p53 acts as potent tumor-suppressor gene independent of its well-documented effects on tumor-cell proliferation and apoptosis. p53 activates target genes in a murine fibrosarcoma cell-line but does not affect tumor cell-cycle progression or survival. Exogenous expression of wt-p53 does, however, block the angiogenic potential of the tumor cells resulting in formation of dormant tumors in vivo. These data provide evidence that: (1) p53 acts as a tumor suppressor gene independent of its anti-proliferative effects; (2) By inhibiting angiogenesis p53 can indirectly induce apoptosis in vivo but not in vitro; (3) p53-gene therapy which alters a tumors angiogenic potential, can revert tumors to a dormant phenotype.

Animals↗

Differential contribution of the ERK and JNK mitogen-activated protein kinase cascades to Ras transformation of HT1080 fibrosarcoma and DLD-1 colon carcinoma cells.

Although an important contribution of ERK and JNK mitogen-activated protein kinase (MAPK) activation in Ras transformation of rodent fibroblasts has been determined, their role in mediating oncogenic Ras transformation of human tumor cells remains to be established. We have utilized the human HT1080 fibrosarcoma and DLD-1 colon carcinoma cell lines, which contain endogenous mutated and oncogenic N- and K-ras alleles, respectively, to address this role. Study of these cells is advantageous over Ras-transformed rodent model cell systems for two key reasons. First, the ras mutations occurred naturally in the progression of the tumors from which the cell lines were derived, rather than due to overexpression of an exogenously introduced gene. Second, although these tumor cells possess defects in multiple genetic loci, it has been established that mutated Ras contributes significantly to the transformed phenotype of these cells. Clonal variant lines of HT1080 and DLD-1 have been isolated which have lost the oncogenic ras allele and exhibit a corresponding impairment in growth transformation in vitro and in vivo. We found that upregulation of Raf/MEK/ERK and JNK correlated with expression of oncogenic Ras in HT1080, but not DLD-1 cells. Furthermore, inhibition of ERK activation in parental HT1080 cells caused the same changes in cell morphology and actin stress fiber organization seen with loss of expression of activated N-Ras(61K). Thus, we suggest that constitutive activation of the Raf/MEK/ERK and JNK pathways is necessary for Ras-induced transformation of HT1080 but not DLD-1 cells. These results emphasize that cell type differences exist in the signaling pathways by which oncogenic Ras causes transformation.

3T3 Cells↗

Plakoglobin is a new target gene of histone deacetylase in human fibrosarcoma HT1080 cells.

Histone deacetylase (HDAC) plays a key role in gene expression, by suppressing the transcription of a number of target genes. Identification of such genes is important for deciphering the functional role of HDAC. Here, using cancer gene-focused DNA microarray analysis, we identified plakoglobin as a new target gene of HDAC. Functional inhibition of HDAC by its specific inhibitors induced the expression of plakoglobin by eight-fold in human fibrosarcoma HT1080 cells. However, the expression of beta-catenin, which is closely related to plakoglobin, was not altered, implying the specific function of HDAC in plakoglobin expression. Using antiacetyl-H4 antibody, chromatin immunoprecipitation analysis revealed that the distal region (-945 approximately -646) of the promoter of plakoglobin is responsible for the HDAC-mediated repression of the gene. Moreover, the induced expression of plakoglobin by the inhibition of HDAC activated the Tcf/Lef-dependent luciferase reporter gene, a well-known downstream effector of the Wnt signaling pathway. Furthermore, transient transfection of plakoglobin also activated Tcf/Lef reporter gene expression. Taken together, our results demonstrate that plakoglobin is a new target gene governed by HDAC, and that it acts as an oncogene in HT1080 cells.

Azacitidine↗

Acquired resistance to reoviral oncolysis in Ras-transformed fibrosarcoma cells.

Reovirus shows considerable potential as an oncolytic agent for Ras-activated tumors and is currently in clinical trials. Here we ask whether such tumor cell lines can acquire resistance to reoviral oncolysis. We challenged human HT1080 fibrosarcoma cells that carry a Ras mutation by prolonged exposure to reovirus, thereby yielding highly virus-resistant HTR1 cells. These cells are persistently infected with reovirus, exhibit high Ras activity and retain the original Ras gene mutation, showing that resistance to reovirus can be displayed in cells with active Ras. The HTR1 cells also exhibit reduced cellular cathepsin B activity, which normally contributes to viral entry and activation. Persistently infected HTR1 cells were not tumorigenic in vivo, whereas immunologically cured virus-free HTR1 cells were highly tumorigenic. Thus, acquisition of resistance to reovirus may constrain therapeutic strategies. To determine whether reoviral resistance is associated with a general reduction in apoptotic potential, we challenged the HTR1 cells with apoptotic inducers and E1B-defective adenovirus, resulting in significant apoptosis and cell death following both approaches. Therefore, even if resistance to reoviral oncolysis should arise in tumor cells in vivo, other therapeutic strategies may nevertheless remain effective.

Base Sequence↗

Evaluation of maxillofacial fibrosarcoma using computer graphics and spiral computed tomography.

This paper describes the appearance of three cases of maxillofacial fibrosarcoma in multiplanar (MPR) and three-dimensional reconstructed computed tomography (3DCT). The images were analysed by two oral and maxillofacial radiologists and one neuroradiologist. All of the cases clearly demonstrated the usefulness of the interactive MPR and 3DCT in the diagnosis and evaluation of the extent of these maxillofacial tumors.

Cheek↗

Dexamethasone modulates the metabolism of type IV collagen and fibronectin in human basement-membrane-forming fibrosarcoma (HT-1080) cells.

The effect of dexamethasone on the synthesis and degradation of type IV collagen was studied in human fibrosarcoma cells, HT-1080. A dexamethasone concentration as low as 0.1 microM markedly increased collagen synthesis in HT-1080 cells labelled with [14C]proline. The increase in type IV collagen synthesis was not specific, since total protein synthesis was also increased. Further studies indicated that part of the increase was due to an increase in the specific radioactivity of the intracellular proline pool, after dexamethasone treatment. In fact, with dexamethasone concentrations of 0.1-10 microM the relative collagen synthesis was decreased, indicating that synthesis of other protein was increased more than that of type IV collagen. This was also confirmed by measuring the relative amount of type IV collagen RNA by using recombinant plasmid cDNA specific for the human procollagen pro alpha l (IV) RNA. The results indicated that relative collagen synthesis and the relative amount of type IV collagen messenger RNA was decreased similarly, indicating that dexamethasone affected type IV collagen synthesis at the pre-translational level. The dexamethasone-induced effect on total protein and collagen synthesis was maximal after 12-24 h. Dexamethasone induced a marked accumulation of collagen into the cell layer, leading to diminished deposition of soluble collagen into the medium. Since bacterial-collagenase treatment of the cell layer drastically decreased the collagen content of the dexamethasone-treated cells, this indicates that dexamethasone caused an accumulation of collagen into the extracellular matrix of the cell layer. In contrast, the amount of fibronectin was markedly increased in the medium. Dexamethasone decreased the type IV collagen-degrading activity in HT-1080 cells. The HT-1080 cells contained glucocorticoid receptors, as demonstrated by two different methods: by a whole-cell binding assay and by using a cytosol-gel-filtration method. The number of specific binding sites was similar to that in human skin fibroblasts. In conclusion, glucocorticoids affect the metabolism of type IV collagen and fibronectin in HT-1080 cells, and, since these cells contain specific glucocorticoid receptors, the effects are apparently receptor-mediated.

Basement Membrane↗

Purification and characterization of matrix metalloproteinase 9 from U937 monocytic leukaemia and HT1080 fibrosarcoma cells.

The precursor of matrix metalloproteinase 9 (proMMP-9), also known as '92 kDa progelatinase/type IV procollagenase', was purified from the conditioned medium of U937 monocytic leukaemia and HT1080 fibrosarcoma cell lines stimulated with phorbol 12-myristate 13-acetate. ProMMP-9 in these culture media is non-covalently complexed with the 29 kDa tissue inhibitor of metalloproteinases (TIMP), but free proMMP-9 was separated from the TIMP-proMMP-9 complex by chromatography on Green A Dyematrex gel. The final product was homogeneous on SDS/PAGE, with a molecular mass of 88 kDa without reduction and 92 kDa with reduction. Treatment of proMMP-9 with 4-aminophenylmercuric acetate converted the 88 kDa precursor into 80 kDa and 68 kDa forms. Gelatin-containing zymographic analysis showed zones of lysis associated with all three species. However, only the 68 kDa species was shown to be catalytically active by its ability to bind to alpha 2-macroglobulin. In the presence of an equimolar amount of TIMP, only the 80 kDa species was generated by treatment with 4-aminophenylmercuric acetate, but no enzyme activity was detected. This indicates that TIMP binds to the 80 kDa intermediate and inhibits the generation of the active 68 kDa species. Eight endopeptidases (trypsin, chymotrypsin, plasmin, plasma kallikrein, thrombin, cathepsin G, neutrophil elastase and thermolysin) were tested for their ability to activate proMMP-9. Of them, trypsin was the most effective activator of proMMP-9. Only partial activation (10-30%) was observed with plasmin, cathepsin G and chymotrypsin. The active forms generated by trypsin were identified as 80 kDa, 74 kDa and 66 kDa by their abilities to bind to alpha 2-macroglobulin. In the presence of an equimolar amount of TIMP, proMMP-9 was also converted into the same molecular-mass species by trypsin, but they were not proteolytically active. This suggests activated MMP-9 is inhibited by TIMP. Activated MMP-9 digested gelatin, type-V collagen, reduced carboxymethylated transferrin and, to a lesser extent, type-IV collagen and laminin A chain. The specific activity against gelatin was estimated to be 15,000 units/mg (1 unit = 1 microgram of gelatin degraded/min at 37 degrees C) by titration with alpha 2-macroglobulin. Comparative studies on digestion of gelatin and collagen types IV and V by MMP-9 and MMP-2 indicated that both enzymes degrade these substrates into similar fragments. However, the susceptibilities of laminin, fibronectin and reduced carboxymethylated transferrin to these two MMPs were sufficiently different to indicate differences in substrate specificities between these two closely related proteinases.

Electrophoresis, Polyacrylamide Gel↗

Induction of tissue transglutaminase by dexamethasone: its correlation to receptor number and transglutaminase-mediated cell death in a series of malignant hamster fibrosarcomas.

Treatment of the hamster fibrosarcoma cell lines (Met B, D and E) and BHK-21 hamster fibroblast cells with the glucocorticoid dexamethasone led to a powerful dose-dependent mRNA-synthesis-dependent increase in transglutaminase activity, which can be correlated with dexamethasone-responsive receptor numbers in each cell line. Increasing the number of dexamethasone-responsive receptors by transfection of cells with the HG1 glucocorticoid receptor protein caused an increase in transglutaminase activity that was proportional to the level of transfected receptor. In all experiments the levels of the tissue transglutaminase-mediated detergent-insoluble bodies was found to be comparable with increases in transglutaminase activity. Despite an increase in detergent-insoluble body formation, an increase in apoptosis as measured by DNA fragmentation was not found. Incubation of cells with the non-toxic competitive transglutaminase substrate fluorescein cadaverine led to the incorporation of this fluorescent amine into cellular proteins when cells were damaged after exposure to trypsin during cell passage. These cross-linked proteins containing fluorescein cadaverine were shown to be present in the detergent-insoluble bodies, indicating that the origin of these bodies is via activation of tissue transglutaminase after cell damage by trypsinization rather than apoptosis per se, since Met B cells expressing the bcl-2 cDNA were not protected from detergent-insoluble body formation. We describe a novel mechanism of cell death related to tissue transglutaminase expression and cell damage.

Animals↗

Sclerosing epithelioid fibrosarcoma: a study of five cases emphasizing diagnostic criteria.

AIMS: To study the clinical and histopathological features of sclerosing epithelioid fibrosarcoma, and to define diagnostic criteria for this uncommon soft-tissue tumour. METHODS AND RESULTS: Standard histological, immunohistochemical and ultrastructural techniques were applied to five tumours from head and neck, chest wall and groin. Tumours consisted of groups of monomorphic rounded/epithelioid cells surrounded by a prominent collagenous stroma. Tumour cells showed positive vimentin staining but were negative for other markers. They contained prominent rough endoplasmic reticulum and a large Golgi apparatus which in one case was producing collagen secretion granules, an ultrastructural marker for collagen production. Three patients had medium to long-term survival (3-7 years). Of these, one was disease-free for 3 years, and two experienced multiple recurrences: one of the latter died of metastatic disease. CONCLUSION: Criteria for diagnosing this uncommon tumour include: small to medium cell size, clear or pale cytoplasm, cellular arrangement in cords and strands, dense collagenous stroma; vimentin staining; rough endoplasmic reticulum and a Golgi apparatus producing, in well preserved examples, collagen secretion granules. The paper emphasizes the value of electron microscopy, supporting an appropriate histological picture and immunophenotype, in identifying these relatively low-grade sarcomas.

Adult↗

Overexpression of MDM2 in a sclerosing epithelioid fibrosarcoma: genetic, immunohistochemical and ultrastructural study of a case.

Sclerosing epithelioid fibrosarcoma (SEF) is an extremely rare soft-tissue neoplasm. Here, we describe the molecular genetic alterations and histological, immunohistochemical and ultrastructural features of a primary SEF arising in the retroperitoneum. The tumor consisted of uniform small round to ovoid epithelioid cells, arranged in nests and cords and surrounded by a prominent hyalinized collagenous matrix. The tumor cells expressed only vimentin. Ultrastructurally, the tumor cells showed features of fibroblasts, with an abundant rough endoplasmic reticulum in the cytoplasm. Neither p53 gene mutations nor p53 protein overexpression were detected, but more than 70% of all tumor cells showed strong immunoreactivity with murine double minute 2 (MDM2). Our results suggest that MDM2 overexpression is likely to play a role in tumorigenesis in this lesion in p53-dependent or p53-independent pathways. To our knowledge, the present study is the first molecular genetic study of this rare lesion. Further studies will be necessary to clarify the molecular basis of tumorigenesis of this rare lesion.

Aged↗

Regression of congenital fibrosarcoma to hemangiomatous remnant with histological and genetic findings.

We report a rare case of congenital fibrosarcoma (CFS) showing regression during the course of disease, in which the histological and genetic alterations were investigated. This CFS, located on the patient's right hand, was a hemangiopericytomatous hypervascular tumor showing frequent mitosis and necrosis. Small lymphocytes, predominantly cytotoxic T cells and natural killer cells, infiltrated the tumor. At the age of 3 months, the patient received a partial resection of the tumor. At the age of 1 year, the hemangiopericytomatous tumor with a dilated vascular lumen remained, although most of the tumor cells exhibited focal necrosis with calcification and no mitotic activity. Lymphocytes increased in number and intermingled with the tumor cells. At the age of 4 years, vascular tissue consisting of inner endothelial cells and surrounding pericytomatous actin-positive cells remained at the previous tumor locus. With reverse transcription-polymerase chain reaction analysis, ETV6-NTRK3 fusion transcripts were detected in tumor samples at 3 months and at 1 year, but not from those at 4 years of age. These genetic and histological changes suggest that the CFS either completely disappeared by apoptosis or showed mature transformation to hemangiomatous tissue with aging.

Apoptosis↗

Three-dimensional angioarchitecture in transplantable rat fibrosarcomas.

Three-dimensional angioarchitecture in a transplantable fibrosarcoma (SS) in F344 rats was investigated by scanning electron microscopy (SEM) of vascular corrosion casts. Tumours were produced in syngeneic rats by implantation of a tumour fragment from another SS tumour. Viable SS tumours, observed up to post-implantation (PI) week 5, showed a high degree of vascularization, consisting of arterioles and veins, and intertwining capillaries branching from such vessels. The capillaries showed numerous finger-like outgrowths, indicating active sprouting of endothelial cells and contributing to tumour growth. In contrast, SS tumours in rats given a single dose (4 mg/kg/bodyweight) of cisplatin at PI week 1 were reduced in volume, lacking in capillary outgrowths, and of low vascular density. Necrotic areas in SS tumours were surrounded by capillaries with sharp tips and wrinkled surfaces. Thus, the findings indicated differences in three-dimensional angioarchitecture between vigorously developing tumours and (1) tumours degenerating as the result of treatment with an anti-cancer drug, or (2) necrotic tumour tissues. SEM of vascular corrosion casts may prove useful for the evaluation of neovascularization in mesenchymal tumours.

Animals↗

The role of preoperative chemotherapy in the treatment of infantile fibrosarcoma.

Infantile fibrosarcoma (IFS) is a rare tumor most often affecting the extremities of infants and young children. Unlike its adult counterpart, IFS has a low potential for metastatic spread, and surgical extirpation alone has therefore resulted in an excellent prognosis. The amputation rate, however, exceeds 50%. The dramatic response in 2 recent cases to preoperative chemotherapy, given in an attempt to avoid amputation, prompted this report and a review of the literature.

Antineoplastic Combined Chemotherapy Protocols↗

Inhibitory effect of magnolol and honokiol from Magnolia obovata on human fibrosarcoma HT-1080. Invasiveness in vitro.

We investigated the inhibitory effect of Magnolia obovata Thunb. bark ethanol extracts on human fibrosarcoma HT-1080 cells invasion in a reconstituted basement membrane [Matrigel (MG)]. We found that the effective components of the bark ethanol extracts were magnolol and honokiol, two biphenyl compounds. The extracts, magnolol and honokiol, did not affect HT-1080 cells adhesion to MG, but did inhibit HT-1080 cells migration at a high concentration (100 microM). HT-1080 cells secrete matrix metalloproteinase (MMP)-9, which degrades the extracellular matrix as a part of the invasive process. Magnolol and honokiol inhibited the activity of MMP-9, which may have been responsible, in part, for the inhibition of tumor cell invasiveness.

Antineoplastic Agents, Phytogenic↗