Flavonoid glycosides isolated from Salicornia herbacea inhibit matrix metalloproteinase in HT1080 cells

Flavonoid glycosides, isorhamnetin 3-capital O, Cyrillic-beta-d-glucoside, and quercetin 3-O-beta-d-glucoside were isolated from Salicornia herbacea and their inhibitory effects on matrix metalloproteinase-9 and -2 (MMP-9 and -2) were evaluated in human fibrosarcoma cell line (HT1080). In zymography experiments, these flavonoid glycosides led to the reduction of the expression levels and activities of MMP-9 and -2 without any significant difference between these flavonoid glycosides. Protein expression levels of both MMP-9 and MMP-2 were inhibited and TIMP-1 (tissue inhibitor of metalloproteinase-1) protein level was enhanced by these flavonoid glycosides. Moreover, a transfection study carried out with AP-1 reporter construct revealed that the reporter activity was suppressed by treatment with isorhamnetin 3-capital O, Cyrillic-beta-d-glucoside. Therefore, these results suggested that these flavonoid glycosides have a potential as valuable natural chemopreventive agents for cancer.

Frzb, a secreted Wnt antagonist, decreases growth and invasiveness of fibrosarcoma cells associated with inhibition of Met signaling

Soft tissue sarcomas (STS) have a strong propensity for aggressive growth and metastasis. We showed that the secreted Wnt antagonist Frzb exhibited potent antitumor activity against prostate cancer, an epithelial type of malignancy. In this study, we further showed the antitumor efficacy of Frzb in STS, a mesenchymal group of cancer. Frzb transfection of HT1080 (fibrosarcoma) and SW872 (liposarcoma) cell lines and their conditioned media resulted in a significant reduction in cellular invasion, motility, and colony formation in soft agar compared with vector control-transfected cells. In a xenograft mouse model, Frzb dramatically suppressed tumor growth of HT1080 cells in nude mice. In a tail-vein injection metastatic model, Frzb-transfected HT1080 cells formed fewer and smaller lung nodules than vector control cells. In addition, we identified new mechanisms for Frzb antitumor activities. Frzb reduced c-Met expression and inhibited Met-mediated signaling, associated with up-regulation of epithelial markers (i.e., keratins 8 and 18) and down-regulation of mesenchymal markers (i.e., vimentin, N-cadherin, fibronectin, Slug, and Twist). Similar to Frzb, silencing of c-Met by short hairpin RNA or using a dominant-negative LRP5 receptor also suppressed Met signaling, leading to reduced cellular motility, invasion, and in vivo tumor growth. Given recent studies indicating an important role of c-Met in sarcoma development and progression, our data showed that Frzb expression was significantly inversely correlated with Met expression in both STS cell lines and tissues. These results suggested the usefulness of Frzb in modulating Met signaling as a new treatment strategy for STS.

In vivo 19F MR studies of fluorine labeled photosensitizers in a murine tumor model

The main focus of this report is the MR spectroscopy of the changes in the concentration of fluorine labeled photosensitizer that occur following the IP administration. This process is studied by (19)F in vivo MR methodology in a murine tumor model. The animal model used in these studies was mice bearing radiation induced fibrosarcoma (RIF) tumor on the foot dorsum. The mice were injected with a solution of approximately 100 micro-moles of the fluorinated photosensitizer and the (19)F MR examination of the photosensitizer in the tumor or the muscle was performed. The pharmacokinetic (PK) profile for each labeled compound was generated using the (19)F MR data at various time points post photosensitizer administration. The pharmacokinetic parameters were analyzed and the relationship of these results to photodynamic therapy is discussed. The (19)F MR methods clearly demonstrate utility in measuring the pharmacokinetic profiles and provide a new approach in the evaluation of appropriate photosensitizers for use in preclinical mammalian systems.

Demonstration of inflammation-induced cancer and cancer immunoediting during primary tumorigenesis

Here we report the effects of loss of the Toll-like receptor-associated signaling adaptor myeloid-differentiation factor 88 (MyD88) on tumor induction in two distinct mouse models of carcinogenesis. The 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol 13-acetate (TPA)-induced skin papilloma model depends on proinflammatory processes, whereas the 3'-methylcholanthrene (MCA) induction of fibrosarcoma has been used by tumor immunologists to illustrate innate and adaptive immune surveillance of cancer. When exposed to a combination of DMBA/TPA, mice lacking MyD88 formed fewer skin papillomas than genetically matched WT controls treated in a similar manner. Unexpectedly, however, fewer MyD88-/- mice formed sarcomas than WT controls when exposed to MCA. In contrast, MyD88-deficient mice did not show a defective ability to reject highly immunogenic transplanted tumors, including MCA sarcomas. Despite the reported role of TNF in chronic inflammation, TNF-deficient mice were significantly more susceptible to MCA-induced sarcoma than WT mice. Overall, these data not only confirm the key role that MyD88 plays in promoting tumor development but also demonstrate that inflammation-induced carcinogenesis and cancer immunoediting can indeed occur in the same mouse tumor model.

Modulation of glucose metabolism inhibits hypoxic accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha)

BACKGROUND AND PURPOSE

The hypoxic accumulation of the transcription factor subunit hypoxia-inducible factor-1alpha (HIF-1alpha), a potential endogenous hypoxia marker and therapeutic target, has recently been shown to strongly depend on glucose availability. The aim of this study was to investigate the underlying mechanism of this effect.

MATERIAL AND METHODS

HIF-1alpha protein levels were studied by Western blotting in HT 1080 human fibrosarcoma cells and in a hypoxia-responsive element green fluorescent protein (HRE-GFP) reporter assay in stably transfected HT 1080 cells treated with hypoxia (0.1% O(2), 12 h) and glycolysis inhibitors 2-deoxyglucose (2-DG) or iodoacetate (IAA). HIF-1alpha mRNA expression was quantified via real-time polymerase chain reaction (RT-PCR).

RESULTS

Both inhibitors drastically reduced hypoxic HIF-1alpha accumulation (2-DG + hypoxia 2% mean HIF-1alpha protein level vs. 59% hypoxia alone; IAA + hypoxia 13% mean HIF-1alpha protein level vs. 96% hypoxia alone), an effect not rescued by the addition of pyruvate and confirmed in an HRE-GFP reporter assay in stably transfected HT 1080 cells. RT-PCR under identical conditions showed no effect of glycolysis inhibition on HIF-1alpha mRNA levels, suggesting a translational or posttranslational mechanism.

CONCLUSION

The effect of glycolysis modulation on the HIF-1alpha levels in tumor cells may provide a novel approach to therapeutically target HIF-1alpha.

In vivo optical imaging of CD13/APN-expression in tumor xenografts

The metalloexopeptidase CD13/aminopeptidase N (APN) has been shown to be involved in cancer angiogenesis, invasion, and metastasis. Therefore, a CD13/APN-targeted NGR-peptide was labeled with the cyanine dye Cy 5.5 and applied to image tumor xenografts with different APN-expression levels using both planar and tomographic optical imaging methods. In vitro, the peptide-dye conjugate showed a clear binding affinity to APN-positive HT-1080 cells, while negative MCF-7 cells and predosing with the free NGR-peptide revealed little to no fluorescence. In vivo, tumor xenografts (n>or=5) were clearly visualized by two-dimensional (2-D) planar fluorescence reflectance imaging (FRI) and three-dimensional (3-D) fluorescence mediated tomography (FMT) up to 24 h after injection. FMT also allowed us to quantify fluorochrome distribution in deeper tissue sections, showing an average fluorochrome concentration of 306.7+/-54.3 nM Cy 5.5 (HT-1080) and 116.0+/-18.3 nM Cy 5.5 (MCF-7) in the target tissue after 5 h. Competition with the free NGR-peptide resulted in a reduction of fluorochrome concentration in HT-1080 tumor tissue (195.3+/-21.9 nM; 5 h). We thus conclude that NGR-Cy 5.5 combined with novel tomographic optical imaging methods allows us to image and quantify tumor-associated CD13/APN expression noninvasively. This may be a promising strategy for a sensitive evaluation of tumor angiogenesis in vivo.

Collagen-binding domains of gelatinase A and thrombospondin-derived peptides impede endocytic clearance of active gelatinase A and promote HT1080 fibrosarcoma cell invasion

Gelatinase A (matrix metalloproteinase-2, MMP-2) binds to several proteins through its collagen-binding domains (CBDs). Surface plasmon resonance analysis revealed a strong interaction between CBD123 and thrombospondin-1 (TSP-1), with a K(D) value of 2x10(-9) M. CBD123, as well as individual domains, behave as competitive inhibitors of the TSP-1-directed endocytic clearance of active MMP-2, but not of its latent form, by HT1080 fibrosarcoma cells. Enhanced level of active MMP-2 in conditioned medium was associated to increased matrigel invasion. Similarly, GGWSHWSPWSS and GGWSHW peptides, as tryptophan-rich peptides within properdin-repeat motifs (TSRs) of TSP-1, promoted MMP-2 accumulation and cell invasiveness. Our data document the importance of TSP-1 in promoting MMP-2-mediated cancer cell invasion through interaction between CBDs of the enzyme and TSRs motifs of TSP-1.

Angiogenic factors FGF2 and PDGF-BB synergistically promote murine tumor neovascularization and metastasis

Tumors produce multiple growth factors, but little is known about the interplay between various angiogenic factors in promoting tumor angiogenesis, growth, and metastasis. Here we show that 2 angiogenic factors frequently upregulated in tumors, PDGF-BB and FGF2, synergistically promote tumor angiogenesis and pulmonary metastasis. Simultaneous overexpression of PDGF-BB and FGF2 in murine fibrosarcomas led to the formation of high-density primitive vascular plexuses, which were poorly coated with pericytes and VSMCs. Surprisingly, overexpression of PDGF-BB alone in tumor cells resulted in dissociation of VSMCs from tumor vessels and decreased recruitment of pericytes. In the absence of FGF2, capillary ECs lacked response to PDGF-BB. However, FGF2 triggers PDGFR-alpha and -beta expression at the transcriptional level in ECs, which acquire hyperresponsiveness to PDGF-BB. Similarly, PDGF-BB-treated VSMCs become responsive to FGF2 stimulation via upregulation of FGF receptor 1 (FGFR1) promoter activity. These findings demonstrate that PDGF-BB and FGF2 reciprocally increase their EC and mural cell responses, leading to disorganized neovascularization and metastasis. Our data suggest that intervention of this non-VEGF reciprocal interaction loop for the tumor vasculature could be an important therapeutic target for the treatment of cancer and metastasis.

Mechanism of reoxygenation after antiangiogenic therapy using SU5416 and its importance for guiding combined antitumor therapy

Emerging preclinical studies support the concept of a transient "normalization" of tumor vasculature during the early stage of antiangiogenic treatment, with possible beneficial effects on associated radiotherapy or chemotherapy. One key issue in this area of research is to determine whether this feature is common to all antiangiogenic drugs and whether the phenomenon occurs in all types of tumors. In the present study, we characterized the evolution of the tumor oxygenation (in transplantable liver tumor and FSAII tumor models) after administration of SU5416, an antagonist of the vascular endothelial growth factor receptor. SU5416 induced an early increase in tumor oxygenation [measured by electronic paramagnetic resonance (EPR)], which did not correlate with remodeling of the tumor vasculature (assessed by CD31 labeling using immunohistochemistry) or with tumor perfusion (measured by dynamic contrast enhanced-magnetic resonance imaging). Inhibition of mitochondrial respiration (measured by EPR) was responsible for this early reoxygenation. Consistent with these unique findings in the tumor microenvironment, we found that SU5416 potentiated tumor response to radiotherapy but not to chemotherapy. In addition to the fact that the characterization of the tumor oxygenation is essential to enable correct application of combined therapies, our results show that the long-term inhibition of oxygen consumption is a potential novel target in this class of compounds.

Functional analysis of a histone deacetylase-like protein of Thermus caldophilus GK24 in mammalian cell

The function of eukaryotic histone deacetylase (HDAC) has been extensively studied for its critical role in transcriptional regulation and carcinogenesis. However that of the prokaryotic counterpart remains largely unknown. Recently, we cloned HDAC-like protein in Thermus caldophilus GK24 (Tca HDAC) from a genomic library of the microorganism based on homology analysis with human HDAC1. To explore the function of Tca HDAC in mammalian cells, Tca HDAC gene expressing vector was transfected into a human fibrosarcoma cell line, HT1080. Tca HDAC was mainly localized in nuclei of the mammalian cells as a human HDAC1 was, due to an N-terminal HDAC association domain. We further generated histidine-substituted Tca HDAC mutants and investigated their role in biochemical and cellular activity of the enzyme. Tca HDAC mutants exhibited dramatic loss of enzymatic activity and conditioned media (CM) from HT1080 cells transfected with mutant Tca HDAC was unable to stimulate angiogenic phenotypes of endothelial cells in vitro whereas that of wild Tca HDAC did. Collectively, these results demonstrate that a prokaryotic histone deacetylase from T. caldophilus GK24 is functionally active in mammalian cells and its function in gene expression is conserved from prokaryotes to eukaryotes.

Antitumor and anti-invasive effects of diverse new macrocyclic lactones, alkylolides and alkenylolides, and their enhancement by hyperthermia

Alkylolides and alkenylolides of 198-254 Da such as hexadecan-16-olide and 9-hexadecen-16-olide were chemically synthesized in the present study as new macrocyclic lactones that are structurally different from widespread natural macrocyclic lactones including bryostatin (887 Da) and rhizoxin (613 Da), and were investigated for antitumor activity to Ehrlich ascites tumor cells by mitochondrial dehydroganase-based WST-1 assay and dye-exclusion assay. Of the alkylolides having 12, 15 or 16 carbon-atoms (D12:0, P15:0 or H16:0) and alkenylolides having 15 or 16 carbon-atoms with a double bond (P15:1 or H16:1), H16:0 was the most carcinostatic when administered at 37 degrees C for 20 h, with cell deformation and microvillus disappearance as detected by scanning electron microscopy. The carcinostatic activity was increased markedly for H16:0 and P15:0 when the administration period was prolonged to 72 h, but was not enhanced by intramolecular introduction of a double bond for P15:1 or H16:1. Hyperthermia at 42 degrees C for 30 min additively intensified the carcinostatic activity for H16:0 and P15:0, but scarcely for D12:0, and intensified the alkenyloides P15:1 and H16:1 only upon the subsequent 72-h treatment. Invasion of human fibrosarcoma HT-1080 cells through the reconstituted basement membrane was inhibited by alkyl- and alkenylolides even after the short-term exposure at 25 microM for 3 h without diminishing the cell viability. H16:0 also exhibited the most inhibitory activity to tumor invasion in addition to the highest carcinostatic activity. Both inhibitions were promoted by combination with hyperthermia. Thus diverse alkyl-/alkenylolides, may be potent multi-applicable anticancer agents in terms of either dual inhibitory activities against both tumor progression and invasion or hyperthermia-combined therapy.

A comparative evaluation of EPR and OxyLite oximetry using a random sampling of pO(2) in a murine tumor

Methods currently available for the measurement of oxygen concentrations (oximetry) in viable tissues differ widely from each other in their methodological basis and applicability. The goal of this study was to compare two novel methods, particulate-based electron paramagnetic resonance (EPR) and OxyLite oximetry, in an experimental tumor model. EPR oximetry uses implantable paramagnetic particulates, whereas OxyLite uses fluorescent probes affixed on a fiber-optic cable. C3H mice were transplanted with radiation-induced fibrosarcoma (RIF-1) tumors in their hind limbs. Lithium phthalocyanine (LiPc) microcrystals were used as EPR probes. The pO(2) measurements were taken from random locations at a depth of approximately 3 mm within the tumor either immediately or 48 h after implantation of LiPc. Both methods revealed significant hypoxia in the tumor. However, there were striking differences between the EPR and OxyLite readings. The differences were attributed to the volume of tissue under examination and the effect of needle invasion at the site of measurement. This study recognizes the unique benefits of EPR oximetry in terms of robustness, repeatability and minimal invasiveness.

Chemical interactions between fibrosarcoma cancer cells and sensory neurons contribute to cancer pain

In an experimental model of cancer pain, the hyperalgesia that occurs with osteolytic tumor growth is associated with the sensitization of nociceptors. We examined functional and molecular changes in small-diameter dorsal root ganglion (DRG) neurons to determine cellular mechanisms underlying this sensitization. The occurrence of a Ca2+ transient in response to either KCl (25 mM) or capsaicin (500 nM) increased in small neurons isolated from murine L3-L6 DRGs ipsilateral to fibrosarcoma cell tumors. The increased responses were associated with increased mRNA levels for the Ca2+ channel subunit alpha2delta1 and TRPV1 receptor. Pretreatment with gabapentin, an inhibitor of the alpha2delta1 subunit, blocked the increased response to KCl in vitro and the mechanical hyperalgesia in tumor-bearing mice in vivo. Similar increases in neuronal responsiveness occurred when DRG neurons from naive mice and fibrosarcoma cells were cocultured for 48 h. The CC chemokine ligand 2 (CCL2) may contribute to the tumor cell-induced sensitization because CCL2 immunoreactivity was present in tumors, high levels of CCL2 peptide were present in microperfusates from tumors, and treatment of DRG neurons in vitro with CCL2 increased the amount of mRNA for the alpha2delta1 subunit. Together, our data provide strong evidence that the chemical mediator CCL2 is released from tumor cells and evokes phenotypic changes in sensory neurons, including increases in voltage-gated Ca2+ channels that likely underlie the mechanical hyperalgesia in the fibrosarcoma cancer model. More broadly, this study provides a novel in vitro model to resolve the cellular and molecular mechanisms by which tumor cells drive functional changes in nociceptors.

Hypoxia enhances metastatic efficiency in HT1080 fibrosarcoma cells by increasing cell survival in lungs, not cell adhesion and invasion

This study examined possible mechanisms for hypoxia-increased metastasis in a green fluorescent protein-labeled human fibrosarcoma cell line (HT1080). The efficiency of the lung arrest of tumor cells, which can be dependent on the adhesive potential of the tumor cells, was assessed by measuring the level of integrin alpha3beta1 protein and by adhesion assays, whereas the extravasation potential was examined by an invasion assay. These properties were not changed by exposure to hypoxia, indicating that lung arrest and extravasation are unlikely to play a major role in the effect of hypoxia on metastasis in this model. The main effect of hypoxic exposure was found to be increased survival after lung arrest as determined by clonogenic assay of tumor cells recovered from mouse lungs after i.v. injection. Concomitantly, apoptosis was identified as responsible for the death of lung-arrested cells, suggesting the involvement of an altered apoptotic response following hypoxic exposure of these cells. Consistent with this finding, we found that the effect of hypoxia on both increased metastasis and survival of arrested cells was inhibited by treatment with farnesylthiosalicylic acid. However, this effect was not due to down-regulation of hypoxia-inducible factor-1alpha, a mechanism of action of this drug reported by previous studies. Further detailed studies of the mechanisms of action of the drug are needed.

Cellular localization and functional characterization of the equilibrative nucleoside transporters of antitumor nucleosides

Nucleoside transporters play an important role in the disposition of nucleosides and their analogs. To elucidate the relationship between chemosensitivity to antitumor nucleosides and the functional expression of equilibrative nucleoside transporters (ENT), we established stable cell lines of human fibrosarcoma HT-1080 and gastric carcinoma TMK-1 that constitutively overexpressed green fluorescent protein-tagged hENT1, hENT2, hENT3 and hENT4. Both hENT1 and hENT2 were predictably localized to the plasma membrane, whereas hENT3 and hENT4 were localized to the intracellular organelles. The chemosensitivity of TMK-1 cells expressing hENT1 and hENT2 to cytarabine and 1-(3-C-ethynyl-beta-D-ribopentofuranosyl) cytosine increased markedly in comparison to that of mock cells. However, no remarkable changes in sensitivity to antitumor nucleosides were observed in cell lines that expressed both hENT3 and hENT4. These data suggest that hENT3 and hENT4, which are mainly located in the intracellular organelles, are not prominent nucleoside transporters like hENT1 and hENT2, which are responsible for antitumor nucleoside uptake.

Functional analysis of matrix metalloproteinases and tissue inhibitors of metalloproteinases differentially expressed by variants of human HT-1080 fibrosarcoma exhibiting high and low levels of intravasation and metastasis

The role of tumor-derived matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) in cancer cell dissemination was analyzed by employing two variants of human HT-1080 fibrosarcoma, HT-hi/diss and HT-lo/diss, which differ by 50-100-fold in their ability to intravasate and metastasize in the chick embryo. HT-hi/diss and HT-lo/diss were compared by quantitative reverse transcription-PCR and Western blot analyses for mRNA and protein expression of nine MMPs (MMP-1, -2, -3, -7, -8, -9, -10, -13, and -14) and three TIMPs (TIMP-1, -2, and -3) in cultured cells in vitro and in primary tumors in vivo. MMP-1 and MMP-9 were more abundant in the HT-hi/diss variant, both in cultures and in tumors, whereas the HT-lo/diss variant consistently expressed higher levels of MMP-2, TIMP-1, and TIMP-2. Small interfering RNA-mediated down-regulation of MMP-2 and TIMP-2 increased intravasation of HT-lo/diss cells. Coordinately, treatment of the developing HT-hi/diss tumors with recombinant TIMP-1 and TIMP-2 significantly reduced HT-hi/diss cell intravasation. However, a substantial increase of HT-hi/diss dissemination was observed upon small interfering RNA-mediated down-regulation of three secreted MMPs, including the interstitial collagenase MMP-1 and the two gelatinases, MMP-2 and MMP-9, but not the membrane-tethered MMP-14. The addition of recombinant pro-MMP-9 protein to the HT-hi/diss tumors reversed the increased intravasation of HT-hi/diss cells, in which MMP-9 was stably down-regulated by short hairpin RNA interference. This rescue did not occur if the pro-MMP-9 was stoichiometrically complexed with TIMP-1, pointing to a direct role of the MMP-9 enzyme in regulation of HT-hi/diss intravasation. Collectively, these findings demonstrate that tumor-derived MMPs may have protective functions in cancer cell intravasation, i.e. not promoting but rather catalytically interfering with the early stages of cancer dissemination.

An improved bioluminescence resonance energy transfer strategy for imaging intracellular events in single cells and living subjects

Bioluminescence resonance energy transfer (BRET) is currently used for monitoring various intracellular events, including protein-protein interactions, in normal and aberrant signal transduction pathways. However, the BRET vectors currently used lack adequate sensitivity for imaging events of interest from both single living cells and small living subjects. Taking advantage of the critical relationship of BRET efficiency and donor quantum efficiency, we report generation of a novel BRET vector by fusing a GFP(2) acceptor protein with a novel mutant Renilla luciferase donor selected for higher quantum yield. This new BRET vector shows an overall 5.5-fold improvement in the BRET ratio, thereby greatly enhancing the dynamic range of the BRET signal. This new BRET strategy provides a unique platform to assay protein functions from both single live cells and cells located deep within small living subjects. The imaging utility of the new BRET vector is shown by constructing a sensor using two mammalian target of rapamycin pathway proteins (FKBP12 and FRB) that dimerize only in the presence of rapamycin. This new BRET vector should facilitate high-throughput sensitive BRET assays, including studies in single live cells and small living subjects. Applications will include anticancer therapy screening in cell culture and in small living animals.

Factor VIII mRNA expression from a BAC carrying the intact locus made by homologous recombination

Hemophilia A is caused by mutations in the gene encoding factor VIII (F8) and is an important target for gene therapy. The F8 gene contains 26 exons spread over approximately 186 kb and no work using the intact genomic locus has been carried out. We have constructed a 250-kb BAC carrying all 26 exons, the introns, and more than 40 kb of upstream and 20 kb of downstream DNA. This F8 BAC was further retrofitted with either the oriP/EBNA-1 elements from Epstein-Barr virus, which allow episomal maintenance in mammalian cells, or alphoid DNA, which allows human artificial chromosome formation in some human cell lines. Lipofection of the oriP/EBNA-1-containing version into mouse Hepa1-6 cells resulted in expression of F8 mRNA spanning the F8 gene. The >300-kb BAC carrying alphoid DNA was successfully delivered to 293A and HT1080 cells using bacterial delivery, resulting in greater than endogenous levels of F8 mRNA expression.

Expression of E-cadherin, beta-catenin and Ki-67 antigen and their reciprocal correlations in fibrosarcomas of soft tissues in dogs

BACKGROUND

This study aimed at immunocytochemical demonstration of E-cadherin, beta-catenin and Ki-67 expressions and the examination of correlation between these markers in primary fibrosarcomas in dogs.

MATERIALS AND METHODS

Material for the study was sampled in the course of surgery from 24 mongrel dogs aged 5 to 16 years. The neoplastic tumors were subjected to histopathological verification and immunohistochemical reactions were performed to detect the studied markers. Microphotographs of the preparations were subjected to computer-assisted image analysis using the MultiScaneBase V 14.02 software.

RESULTS

Expression of beta-catenin was detected in all tumours examined while E-cadherin was expressed in only 8.2%. Expression of the Ki-67 proliferation-associated antigen was noted in over 33% of the tumours.

CONCLUSION

The lack of correlation (r=-0.1035) between expression of Ki-67 and that of beta-catenin detected here in contrast to the high values of Ki-67 antigen found as a prognostic factor in many other studies allowed us to conclude that the presence of beta-catenin in cells of soft tissue fibrosarcoma in dogs manifested no unequivocal relationship to augmented proliferative potential of neoplastic cells, although it did not exclude participation of the protein in the development of this neoplasia in dogs.

Identification of a novel 82 kDa proMMP-9 species associated with the surface of leukaemic cells: (auto-)catalytic activation and resistance to inhibition by TIMP-1

MMP-9 (matrix metalloproteinase 9) plays a critical role in tumour progression. Although the biochemical properties of the secreted form of proMMP-9 are well characterized, little is known about the function and activity of cell surface-associated proMMP-9. We purified a novel 82 kDa species of proMMP-9 from the plasma membrane of THP-1 leukaemic cells, which has substantial differences from the secreted 94 kDa proMMP-9. The 82 kDa form was not detected in the medium even upon stimulation with a phorbol ester. It is truncated by nine amino acid residues at its N-terminus, lacks O-linked oligosaccharides present in the 94 kDa proMMP-9, but retains N-linked carbohydrates. Incubation of 94 kDa proMMP-9 with MMP-3 generated the well-known 82 kDa active form, but the 82 kDa proMMP-9 was converted into an active species of 35 kDa, which was also produced by autocatalytic processing in the absence of activating enzymes. The activated 35 kDa MMP-9 efficiently degraded gelatins, native collagen type IV and fibronectin. The enzyme was less sensitive to TIMP-1 (tissue inhibitor of metalloproteinase 1) inhibition with IC50 values of 82 nM compared with 1 nM for the 82 kDa active MMP-9. The synthetic MMP inhibitor GM6001 blocked the activity of both enzymes, with similar IC50 values below 1 nM. The 82 kDa proMMP-9 is also produced in HL-60 and NB4 leukaemic cell lines as well as ex vivo leukaemic blast cells. It is, however, absent from neutrophils and mononuclear cells isolated from peripheral blood of healthy individuals. Thus, the 82 kDa proMMP-9 expressed on the surface of malignant cells may escape inhibition by natural TIMP-1, thereby facilitating cellular invasion in vivo.

Induction of p53-Dependent Senescence by the MDM2 Antagonist Nutlin-3a in Mouse Cells of Fibroblast Origin

Cellular senescence is emerging as an important in vivo anticancer response elicited by multiple stresses, including currently used chemotherapeutic drugs. Nutlin-3a is a recently discovered small-molecule antagonist of the p53-destabilizing protein murine double minute-2 (MDM2) that induces cell cycle arrest and apoptosis in cancer cells with functional p53. Here, we report that nutlin-3a induces cellular senescence in murine primary fibroblasts, oncogenically transformed fibroblasts, and fibrosarcoma cell lines. No evidence of drug-induced apoptosis was observed in any case. Nutlin-induced senescence was strictly dependent on the presence of functional p53 as revealed by the fact that cells lacking p53 were completely insensitive to the drug, whereas cells lacking the tumor suppressor alternative reading frame product of the CDKN2A locus underwent irreversible cell cycle arrest. Interestingly, irreversibility was achieved in neoplastic cells faster than in their corresponding parental primary cells, suggesting that nutlin-3a and oncogenic signaling cooperate in activating p53. Our current results suggest that senescence could be a major cellular outcome of cancer therapy by antagonists of the p53-MDM2 interaction, such as nutlin-3a.

Multi-step pericellular proteolysis controls the transition from individual to collective cancer cell invasion

Invasive cell migration through tissue barriers requires pericellular remodelling of extracellular matrix (ECM) executed by cell-surface proteases, particularly membrane-type-1 matrix metalloproteinase (MT1-MMP/MMP-14). Using time-resolved multimodal microscopy, we show how invasive HT-1080 fibrosarcoma and MDA-MB-231 breast cancer cells coordinate mechanotransduction and fibrillar collagen remodelling by segregating the anterior force-generating leading edge containing beta1 integrin, MT1-MMP and F-actin from a posterior proteolytic zone executing fibre breakdown. During forward movement, sterically impeding fibres are selectively realigned into microtracks of single-cell calibre. Microtracks become expanded by multiple following cells by means of the large-scale degradation of lateral ECM interfaces, ultimately prompting transition towards collective invasion similar to that in vivo. Both ECM track widening and transition to multicellular invasion are dependent on MT1-MMP-mediated collagenolysis, shown by broad-spectrum protease inhibition and RNA interference. Thus, invasive migration and proteolytic ECM remodelling are interdependent processes that control tissue micropatterning and macropatterning and, consequently, individual and collective cell migration.

Control of immune responses by antigen-specific regulatory T cells expressing the folate receptor

Immune responses can be enhanced or dampened by differential manipulation of Foxp3-expressing CD25(+)CD4(+) natural regulatory T (Treg) cells versus other naive or activated T cells. By searching for a molecule capable of distinguishing these populations, we here found that natural Treg cells constitutively expressed high amounts of folate receptor 4 (FR4). The expression of FR4 and CD25 also separated antigen-stimulated CD4(+) non-Treg cells into the FR4(hi)CD25(-) and FR4(lo)CD25(+) populations, which were different in proliferation and cytokine secretion upon restimulation. These distinctions showed that antigenic stimulation activated and expanded antigen-specific natural Treg cells as well as effector and memory T cells. Accordingly, FR4(hi)CD25(+)CD4(+) T cells enriched from alloantigen-stimulated T cells suppressed graft rejection. Administration of FR4 monoclonal antibody specifically reduced Treg cells, provoking effective tumor immunity in tumor-bearing animals, whereas similar treatment of normal young mice elicited autoimmune disease. Thus, specific manipulation of FR4(hi)CD25(+)CD4(+) Treg cells helps control ongoing immune responses.

[Effect of temperature and monensin on the level of intracellular sodium and pH in perfused RIF-1 cultured cells]

The direct measurement of temperature in subcutaneously (sc) implanted tumors shows that the actual tumor temperature is by 3-4 degrees C lower than the normal body temperature. Thus, the temperatures usually used for tumor hyperthermia are in fact heating the sc-tumors from 33 to 37 degrees C. The temperature increase during the perfusion of radiation-induced fibrosarcoma (RIF-1) cells from 33 to 37 degrees C caused a reversible increase in intracellular 23Na ([Na+]i) NMR signal intensity by 50-60%. This heating significantly decreased the intracellular pH (pH) in 5 min, but it returned back to the baseline level during the heating period. The 3ATP/P(i) remained generally unchanged throughout the experiment. Monensin, an antitumoral drug and Na+ ionophor, increased [Na+]i by 20% during cell superfusion without heating. When combined, monensin did not increase the heating effect on [Na+]i. However, when monensin was added to the superfusion media, the [Na+]i level did not return to baseline during post-heating recovery, but instead started to increase again. Monensin did not significantly change pH(i) and betaATP/P(i). Our data and the literature show that monensin can accelerate the processes leading to the collapse of the transmembrane Na+ gradient and thus can increase the thermo-sensitivity of tumor cells.

Effective tumor targeted gene transfer using PEGylated adenovirus vector via systemic administration

Conjugation of polyethylene glycol to protein or particles (PEGylation) prolongs their plasma half-lives and promotes their accumulation in tumors due to enhanced permeability and retention (EPR) effect. Although PEGylation of adenovirus vectors (Ads) is an attractive strategy to improve the in vivo kinetics of conventional Ads, the EPR effect of PEGylated Ad (PEG-Ad) had not previously been reported. In this study, we prepared PEG-Ads with PEG at various modification ratios, injected them intravenously into tumor-bearing mice, and determined the blood kinetics, viral distribution, and gene expression patterns, respectively. In addition, we conducted a cancer therapeutic study of PEG-Ad encoding tumor necrosis factor (TNF)-alpha. The plasma half-life of PEG-Ad was longer than that of unmodified-Ad, and accumulation of PEG-Ad in tumor tissue increased as the PEG modification ratio increased. In particular, PEG-Ad with about 90% modification ratio showed higher (35 times) gene expression in tumor and lower (6%) in liver, compared with values for unmodified Ad. Moreover, PEG-Ad encoding TNF-alpha demonstrated not only stronger tumor-suppressive activity but also fewer hepatotoxic side effects compared with unmodified-Ad. PEGylation of Ad achieved tumor targeting through the EPR effect, and these attributes suggest that systemic injection of PEG-Ad has great potential as an anti-tumor treatment.

Pro-MMP-2 activation by the PPARgamma agonist, ciglitazone, induces cell invasion through the generation of ROS and the activation of ERK

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor modulating a variety of biological functions including cancer cell proliferation and differentiation. However, the role of PPARgamma and its ligands in tumor invasion is unclear. To evaluate a possible role for PPARgamma ligands in tumor invasion, we examined whether PPARgamma agonists including pioglitazone, troglitazone, rosiglitazone, and ciglitazone could affect the activity of matrix metalloproteinases (MMPs) in the HT1080 cell line, a well-studied and well-characterized cell line for MMP research. The gelatin zymography assay showed that ciglitazone activated pro-MMP-2 significantly. In addition, ciglitazone increased the expression of MMP-2, which was accompanied by an increase of membrane type 1-MMP (MT1-MMP) expression. The PPARgamma antagonist, GW9662 attenuated the ciglitazone-induced PPARgamma activation but it did not affect the pro-MMP2 activation by ciglitazone, suggesting that the action of ciglitazone on the pro-MMP-2 activation bypassed the PPARgamma pathway. Antioxidants and various inhibitors of signal transduction were used to investigate the mechanism of ciglitazone-induced pro-MMP-2 activation. We found that the sustained production of reactive oxygen species (ROS) was required for pro-MMP-2 activation by ciglitazone. We also found that PB98059, an inhibitor of MEK-ERK, significantly blocked ciglitazone-induced pro-MMP-2 activation and that extracellular signal-regulated kinase (ERK) was hyperphosphorylated by ciglitazone. Moreover, cell invasion was significantly increased by ciglitazone in the HT1080 cell lines, whereas cell motility was not affected. This study suggests that ciglitazone-induced pro-MMP-2 activation increases PPARgamma-independent tumor cell invasion through ROS production and ERK activation in some types of cancer cells.

Dual-color imaging of angiogenesis and its inhibition in bone and soft tissue sarcoma

BACKGROUND

Angiogenesis is a critical step in tumor growth, progression, and metastasis. Soft tissue and bone sarcoma are resistant to most therapeutic approaches. Angiogenesis of these tumors may be an effective target. We hypothesized that we could inhibit tumor growth by targeting angiogenesis in a mouse model of sarcoma. We demonstrate in this report, using powerful color-coded fluorescent imageable tumor-host models, the onset of angiogenesis of these sarcomas and its inhibition.

MATERIALS AND METHODS

Transgenic mice were used as the host in which green fluorescent protein (GFP) is driven by a regulatory element of the stem cell marker nestin (ND-GFP). Nascent blood vessels express ND-GFP in this model. We visualized, by dual-color fluorescence imaging, angiogenesis of sarcoma formed by the HT-1080 human fibrosarcoma cell line expressing red fluorescent protein (RFP) in the ND-GFP mice. Tumor cells were injected into either the muscle or the bone.

RESULTS

Nestin was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumors, including the surrounding tissues. Immunohistochemical staining showed that CD31 colocalized in ND-GFP-expressing nascent blood vessels. The density of nascent blood vessels in the tumor was readily quantitated. The mice were given daily i.p. injections of 5 mg/kg of doxorubicin after implantation of tumor cells. Doxorubicin significantly decreased the mean nascent blood vessel density in the tumors as well as decreased tumor volume.

CONCLUSION

The dual-color model of the ND-GFP nude mouse and RFP sarcoma cells is useful for the visualization and quantitation of bone and soft tissue tumor angiogenesis and evaluation of angiogenic inhibitors for such tumors. These data suggest targeting angiogenesis of sarcomas as a promising clinical approach.

In vivo imaging of changes in tumor oxygenation during growth and after treatment

A novel procedure for in vivo imaging of the oxygen partial pressure (pO2) in implanted tumors is reported. The procedure uses electron paramagnetic resonance imaging (EPRI) of oxygen-sensing nanoprobes embedded in the tumor cells. Unlike existing methods of pO2 quantification, wherein the probes are physically inserted at the time of measurement, the new approach uses cells that are preinternalized (labeled) with the oxygen-sensing probes, which become permanently embedded in the developed tumor. Radiation-induced fibrosarcoma (RIF-1) cells, internalized with nanoprobes of lithium octa-n-butoxy-naphthalocyanine (LiNc-BuO), were allowed to grow as a solid tumor. In vivo imaging of the growing tumor showed a heterogeneous distribution of the spin probe, as well as oxygenation in the tumor volume. The pO2 images obtained after the tumors were exposed to a single dose of 30-Gy X-radiation showed marked redistribution as well as an overall increase in tissue oxygenation, with a maximum increase 6 hr after irradiation. However, larger tumors with a poorly perfused core showed no significant changes in oxygenation. In summary, the use of in vivo EPR technology with embedded oxygen-sensitive nanoprobes enabled noninvasive visualization of dynamic changes in the intracellular pO2 of growing and irradiated tumors.

p21Waf1/Cip1/Sdi1 mediates retinoblastoma protein degradation

Damage-induced G1 checkpoint in mammalian cells involves upregulation of p53, which activates transcription of p21(Waf1) (CDKN1A). Inhibition of cyclin-dependent kinase (CDK)2 and CDK4/6 by p21 leads to dephosphorylation and activation of Rb. We now show that ectopic p21 expression in human HT1080 fibrosarcoma cells causes not only dephosphorylation but also depletion of Rb; this effect was p53-independent and susceptible to a proteasome inhibitor. CDK inhibitor p27 (CDKN1B) also caused Rb dephosphorylation and depletion, but another CDK inhibitor p16 (CDKN2A) induced only dephosphorylation but not depletion of Rb. Rb depletion was observed in both HT1080 and HCT116 colon carcinoma cells, where p21 was induced by DNA-damaging agents. Rb depletion after DNA damage did not occur in the absence of p21, and it was reduced when p21 induction was inhibited by p21-targeting short hairpin RNA or by a transdominant inhibitor of p53. These results indicate that p21 both activates Rb through dephosphorylation and inactivates it through degradation, suggesting negative feedback regulation of damage-induced cell-cycle checkpoint arrest.

Quantitative comparison of tissue oxygen and motexafin lutetium uptake by ex vivo and noninvasive in vivo techniques in patients with intraperitoneal carcinomatosis

Near-infrared diffuse reflectance spectroscopy (DRS) has been used to noninvasively monitor optical properties during photodynamic therapy (PDT). This technique has been extensively validated in tissue phantoms; however, validation in patients has been limited. This pilot study compares blood oxygenation and photosensitizer tissue uptake measured by multiwavelength DRS with ex vivo assays of the hypoxia marker, 2-(2-nitroimida-zol-1[H]-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide (EF5), and the photosensitizer (motexafin lutetium, MLu) from tissues at the same tumor site of three tumors in two patients with intra-abdominal cancers. Similar in vivo and ex vivo measurements of MLu concentration are carried out in murine radiation-induced fibrosarcoma (RIF) tumors (n=9). The selection of optimal DRS wavelength range and source-detector separations is discussed and implemented, and the association between in vivo and ex vivo measurements is examined. The results demonstrate a negative correlation between blood oxygen saturation (StO(2)) and EF5 binding, consistent with published relationships between EF5 binding and electrode measured pO(2), and between electrode measured pO(2) and StO(2). A tight correspondence is observed between in vivo DRS and ex vivo measured MLu concentration in the RIF tumors; similar data are positively correlated in the human intraperitoneal tumors. These results further demonstrate the potential of in vivo DRS measurements in clinical PDT.

Beta-sitosterol-induced-apoptosis is mediated by the activation of ERK and the downregulation of Akt in MCA-102 murine fibrosarcoma cells

Beta-sitosterol (SITO) is a potential candidate for cancer chemotherapy, however, little is known about the cellular and molecular mechanisms in cancer cells. We herein identified how SITO induces anti-proliferation and cell death in MCA-102 fibrosarcoma cells. SITO exposure induced-apoptosis and the cell death resulted from a significant loss of the Bcl-2 and the inhibitor of apoptosis protein (IAP) family (XIAP, cIAP-1 and cIAP-2), and increased Bax with an alteration of p53 and p21. SITO-induced cell death significantly also increased caspase activity and poly(ADP-ribose) polymerase (PARP) cleavage, and caspase-3 inhibitor z-DEVD-fmk significantly inhibited SITO-induced cell death. These data suggest that the activation of caspase-3 is associated with SITO-induced-apoptosis. Treatment with SITO also induced phosphorylation of extracellular-signal regulating kinase (ERK) and p38 mitogen-activated protein kinase (MARK), but not c-Jun N-terminal kinase (JNK). A specific ERK inhibitor PD98059 significantly blocks SITO-induced-apoptosis, whereas a JNK inhibitor SP600125 has no affect. A p38 MAPK inhibitor SB203580 very slightly suppressed cell death. The induction of apoptosis was also accompanied by an inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt, and PI3K inhibitor LY29004 significantly increases SITO-induced cell death. These findings provide evidence demonstrating that the proapoptotic effect of SITO is mediated through the activation of ERK and the block of the PI3K/Akt signal pathway in MCA-102 cells. Therefore, SITO has a strong potential as a therapeutic agent for preventing cancers such as fibrosarcoma.

AKAP12 induces apoptotic cell death in human fibrosarcoma cells by regulating CDKI-cyclin D1 and caspase-3 activity

AKAP12 (A-Kinase anchoring protein 12) is a protein kinase C substrate and a potential tumor suppressor. AKAP12 is down-regulated by several oncogenes and strongly suppressed in various cancers including prostate, ovarian and breast cancers. AKAP12 acts as a regulator of mitogenesis by anchoring key signal proteins such as PKA, PKC, and cyclins. In this study, AKAP12 was found to suppress tumor cell viability by inducing apoptosis via caspase-3 in HT1080 cells. This AKAP12-induced apoptosis was associated with a decreased expression of Bcl-2 and increased expression of Bax. Moreover, AKAP12-transfectant strongly induced the expression of Cip1/p21 and Kip1/p27, but resulted in a decrease in cyclin D1 involved in G(1) progression. Accordingly, these results suggest that AKAP12 may play an important role in tumor growth suppression by inducing apoptosis with the regulation of multiple molecules in the cell cycle progression.

Expression of receptor activator of nuclear factor kappa-B ligand (RANKL) in neoplasms of dogs and cats

BACKGROUND

Receptor activator of nuclear factor kappa-B (RANK), RANK-ligand (RANKL), and the soluble decoy receptor osteoprotegerin (OPG) form a key axis modulating osteoclastogenesis. In health, RANKL-expressing bone stromal cells and osteoblasts activate osteoclasts through RANK ligation, resulting in homeostatic bone resorption. Skeletal tumors of dogs and cats, whether primary or metastatic, may express RANKL and directly induce malignant osteolysis.

HYPOTHESIS

Bone malignancies of dogs and cats may express RANKL, thereby contributing to pathologic bone resorption and pain. Furthermore, relative RANKL expression in bone tumors may correlate with radiographic characteristics of bone pathology.

ANIMALS

Forty-two dogs and 6 cats with spontaneously-occurring tumors involving bones or soft tissues were evaluated.

METHODS

A polyclonal anti-human RANKL antibody was validated for use in canine and feline cells by flow cytometry and immunocytochemistry. Fifty cytologic specimens were collected from bone and soft tissue tumors of 48 tumor-bearing animals and assessed for RANKL expression. In 15 canine osteosarcoma (OSA) samples, relative RANKL expression was correlated with radiographic characteristics of bone pathology.

RESULTS

Expression of RANKL by neoplastic cells was identified in 32/44 canine and 5/6 feline tumor samples. In 15 dogs with OSA, relative RANKL expression did not correlate with either radiographic osteolysis or bone mineral density as assessed by dual energy x-ray absorptiometry.

CONCLUSIONS AND CLINICAL IMPORTANCE

In dogs and cats, tumors classically involving bone and causing pain, often may express RANKL. Confirming RANKL expression in tumors is a necessary step toward the rational institution of novel therapies targeting malignant osteolysis via RANKL antagonism.

Protective effect of Dunaliella salina (Volvocales, Chlorophyta) against experimentally induced fibrosarcoma on wistar rats

The beta-carotene-yielding microalga, Dunaliella salina (Dunal) Teod. maintained in De Walne's medium was harvested and lyophilized. Fibrosarcoma was induced in rats by 20-methylcholanthrene. 0.5 g and 1.0 g of lyophilized D. salina powder was administered to the rats orally through carboxy methyl cellulose. Cisplatin was administered along with vitamin E to compare the protective effect of D. salina against fibrosarcoma. Administration of D. salina decreased the levels of cholesterol and lactate dehydrogenase as well as the activities of catalase, superoxide dismutase, serum aspartate aminotransaminase, serum alanine aminotransferase, when compared to control. A significant reduction in the levels of hepatic and renal RNA and DNA was observed in the sarcoma rats when treated with D. salina powder. Histopathological studies of tumor tissues showed regenerative and regressive changes. beta-carotene globules isolated from the powder of Dunaliella salina confirmed the presence of 9-cis-beta-carotene and all-trans-beta-carotene.

Synthesis and evaluation of a 99mTc-MAMA-propyl-thymidine complex as a potential probe for in vivo visualization of tumor cell proliferation with SPECT

INTRODUCTION

Cytosolic thymidine kinase (TK1) catalyzes phosphorylation of thymidine to its monophosphate. TK1 activity is closely related with DNA synthesis, and thymidine analogs derivatized with bulky carboranylalkyl groups at the N-3 position were reported to be good substrates for TK1. Accordingly, we have synthesized (99m)Tc-MAMA-propyl-thymidine and evaluated it as a potential tumor tracer.

METHODS

The bis(S-trityl)-protected MAMA-propyl-thymidine precursor (3-N-[S-trityl-2-mercaptoethyl]-N-[N'-(S-trityl-2-mercaptoethyl)amidoacetyl]-aminopropyl-thymidine) was prepared in three steps, and its structure was confirmed with (1)H NMR and mass spectrometry. Deprotection of the thiols and labeling with (99m)Tc were done in a two-step, one-pot procedure, yielding (99m)Tc-MAMA-propyl-thymidine, which was analyzed with high-performance liquid chromatography, radio-LC-MS analysis (ESI+) and electrophoresis, and its log P was determined. The biodistribution in normal mice was evaluated, and its biodistribution in a radiation-induced fibrosarcoma (RIF) tumor mouse was compared with that of 3'-deoxy-3'-[(18)F] fluorothymidine [(18)F]FLT.

RESULTS

(99m)Tc-MAMA-propyl-thymidine was obtained with a radiochemical yield of 70%. Electrophoresis indicated that the complex is uncharged, and its log P was 1.0. The molecular ion mass of the Tc complex was 589 Da, which is compatible with the hypothesized N(2)S(2)-oxotechnetium structure. Tissue distribution showed fast clearance from plasma primarily by the hepatobiliary pathway. Whole-body planar imaging after injection of (99m)Tc-MAMA-propyl-thymidine in an RIF tumor-bearing mouse showed high uptake in the liver and the intestines. No uptake was observed in the tumor, in contrast to the clear uptake observed for [(18)F] FLT visualized with muPET.

CONCLUSIONS

Although it has been reported that TK1 accepts large substituents at the N-3 position of the thymine ring, the results of this study show that (99m)Tc-MAMA-propyl-thymidine cannot be used as a single photon emission computed tomography tumor tracer, probably because the (99m)Tc-MAMA ligand is too bulky to be tolerated by TK1.

Hyalinizing spindle cell tumor with giant rosettes arising in the lung: Report of a case with FUS-CREB3L2 fusion transcripts

Hyalinizing spindle cell tumor with giant rosettes (HSCT) is a very uncommon mesenchymal tumor that has similar morphological and biological features to the low-grade fibromyxoid sarcoma (LGFMS). Lung involvement of HSCT is extremely rare, and only one case has been reported in the English-language literature. Reported herein is a case of primary pulmonary HSCT that had FUS-CREB3L2 fusion transcripts, a product of characteristic chromosomal abnormality t(7;16)(q33;p11) of HSCT and LGFMS. The patient was a 50-year-old woman who had a large solitary mass in the lung. Histologically, it was composed of bland spindle cells with variable cellularity deposited in a densely hyalinized stroma alternating with myxoid areas. Characteristic collagen rosettes were scattered in the cellular areas. Reverse transcription-polymerase chain reaction (RT-PCR) assay using formalin-fixed, paraffin-embedded tissue detected FUS-CREB3L2 fusion transcripts. Despite its bland morphology, it is known as low-grade sarcoma and its recognition in the lung would be helpful for accurate diagnosis and proper management of this rare tumor. RT-PCR for detection of FUS-CREB3L2 fusion transcripts is a useful method for differential diagnosis of primary pulmonary HSCT.

P53 expression is associated with malignant potential in xenograft tissues of a fibrosarcoma mouse model

BACKGROUND

The expression of wild-type and mutant p53 was studied in two fibrosarcoma cell lines in a mouse xenograft model.

MATERIALS AND METHODS

Human cell lines HT1080 and Hs913(D)T were implanted in athymic mice via intramuscular (i.m.) or subcutaneous (s.c.) routes. After eight weeks, liver, lung and primary inoculation sites were harvested. Sections were stained using two methods: a) haematoxylin and eosin to detect tumour at implantation site, liver and lung; b) immunohistochemistry using monoclonal antibodies to detect expression of wild-type (wt) and mutant p53.

RESULTS

Both cell lines had similar implantation rates via either route but Hs913(D)T had a higher metastatic rate than HT1080. The Hs913(D)T cells exhibited greater expression of mutant and wild-type p53 than the HT1080 cells.

CONCLUSION

The expression of wild-type and mutant p53 is associated with a cell line of greater malignant potential. The inoculation route does not affect primary tumour uptake or metastatic rate.

Preparation and preliminary biological evaluation of a novel 109Pd labeled porphyrin derivative for possible use in targeted tumor therapy

AIM

The labeling of a porphyrin, a tumor-avid agent, with a beta-emitting radionuclide for evaluating its potential as an agent for targeted tumor therapy is reported. A novel water soluble porphyrin viz. 5,10,15,20-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl]porphyrin radiolabeled with(109)Pd (E(beta(max))=1.12 MeV, Eg=88 keV (3.6%), T1/2=13.7 h) has been prepared. The designing of this agent is based on the speculation that (109)Pd would complex with the tetrapyrrole donor array constituting the porphyrin core, resulting in a species with peripheral hydrophilic residues for facilitating renal excretion.

METHODS

Palladium-109 was produced by thermal neutron bombardment on enriched metallic Pd target at a flux of 3 x 10(13) n/cm(2) x s for 3 days and the porphyrin derivative was synthesized by a multi-step reaction using 3,4 dihydroxybenzaldehyde and pyrrole. The labeling parameters were optimized for obtaining maximum complexation yield and the biological behavior of the radiolabeled porphyrin was studied in Swiss mice bearing fibrosarcoma tumors.

RESULTS

Palladium-109 was produced with a specific activity of approximately 1.85 GBq/mg and approximately 100% radionuclidic purity. Lead-109 complex of the synthesized porphyrin derivative was prepared with excellent radiochemical purity (approximately 98%) and the complex was observed to be stable upto 24 h at room temperature. Results of the biodistribution studies revealed good tumor uptake (2.8+/-0.57%/g) within 30 min post-injection and it remained almost constant till 24 h post-injection. The complex showed predominantly renal clearance (88.68+/-4.01% at 24 h post-injection).

CONCLUSIONS

The high tumor/blood and tumor/muscle ratios (4.36 and 38 at 24 h post-injection) exhibited by the radiolabeled porphyrin indicate its potential for using in targeted tumor therapy.

Peptide-based pharmacomodulation of a cancer-targeted optical imaging and photodynamic therapy agent

We designed and synthesized a folate receptor-targeted, water-soluble, and pharmacomodulated photodynamic therapy (PDT) agent that selectively detects and destroys the targeted cancer cells while sparing normal tissue. This was achieved by minimizing the normal organ uptake (e.g., liver and spleen) and by discriminating between tumors with different levels of folate receptor (FR) expression. This construct (Pyro-peptide-Folate, PPF) is composed of three components: (1) pyropheophorbide a (Pyro) as an imaging and therapeutic agent, (2) peptide sequence as a stable linker and modulator improving the delivery efficiency, and (3) Folate as a homing molecule targeting FR-expressing cancer cells. We observed an enhanced accumulation of PPF in KB cancer cells (FR+) compared to HT 1080 cancer cells (FR-), resulting in a more effective post-PDT killing of KB cells over HT 1080 or normal CHO cells. The accumulation of PPF in KB cells can be up to 70% inhibited by an excess of free folic acid. The effect of Folate on preferential accumulation of PPF in KB tumors (KB vs HT 1080 tumors 2.5:1) was also confirmed in vivo. In contrast to that, no significant difference between the KB and HT 1080 tumor was observed in case of the untargeted probe (Pyro-peptide, PP), eliminating the potential influence of Pyro's own nonspecific affinity to cancer cells. More importantly, we found that incorporating a short peptide sequence considerably improved the delivery efficiency of the probe--a process we attributed to a possible peptide-based pharmacomodulation--as was demonstrated by a 50-fold reduction in PPF accumulation in liver and spleen when compared to a peptide-lacking probe (Pyro-K-Folate, PKF). This approach could potentially be generalized to improve the delivery efficiency of other targeted molecular imaging and photodynamic therapy agents.

Magnetic resonance imaging of temperature-sensitive liposome release: drug dose painting and antitumor effects

BACKGROUND

In preclinical studies, lysolipid-based temperature-sensitive liposomes (LTSLs) containing chemotherapy drugs administered in combination with local hyperthermia have been found to increase tumor drug concentrations and improve antitumor efficacy of the drugs. We used a novel magnetic resonance imaging (MRI) method to measure the temporal and spatial patterns of drug delivery in a rat fibrosarcoma model during treatment with LTSLs containing doxorubicin and an MRI contrast agent (manganese) (Dox/Mn-LTSLs) administered at different times with respect to hyperthermia.

METHODS

Rats bearing 10- to 12-mm fibrosarcomas (n = 6-7 per group) were treated with Dox/Mn-LTSLs (at a dose of 5 mg doxorubicin/kg body weight) before and/or during 60 minutes of local tumor hyperthermia administered via a catheter inserted at the center of the tumor. Drug distribution was monitored continuously via MRI. Magnetic resonance changes were used to calculate intratumoral doxorubicin concentrations throughout treatment. Tumors were monitored until they reached five times their volume on the day of treatment or 60 days. Doxorubicin concentrations and times for tumors to reach five times their volume on the day of treatment were analyzed using the Kruskal-Wallis test and the Kaplan-Meier product-limit method, respectively. All statistical tests were two-sided.

RESULTS

Administration of Dox/Mn-LTSLs before, during, and both before and during hyperthermia yielded central, peripheral, and uniform drug distributions, respectively. Doxorubicin accumulated more quickly and reached higher concentrations in the tumor when Dox/Mn-LTSLs were administered during hyperthermia than when administered before hyperthermia (rate: 9.8 versus 1.8 microg/min, difference = 8.0 microg/min, 95% confidence interval [CI] = 6.8 to 12.8 microg/min, P = .003; concentration: 15.1 versus 8.0 ng/mg, difference = 7.1 ng/mg, 95% CI = 3.6 to 10.6 ng/mg, P = .028). LTSL administered during hyperthermia also yielded the greatest antitumor effect, with a median time for tumors to reach five times their volume on the day of treatment of 34 days (95% CI = 30 days to infinity) compared with 18.5 days (95% CI = 16 to 23 days) for LTSL before hyperthermia and 22.5 days (95% CI = 15 to 25 days) for LTSL before and during hyperthermia.

CONCLUSIONS

In this rat fibrosarcoma model, LTSLs were most effective when delivered during hyperthermia, which resulted in a peripheral drug distribution.

CXC Chemokine Ligand 9/Monokine Induced by IFN-γ Production by Tumor Cells Is Critical for T Cell-Mediated Suppression of Cutaneous Tumors

The role of tumor-produced chemokines in the growth of malignancies remains poorly understood. We retrieved an in vivo growing MCA205 fibrosarcoma and isolated tumor cell clones that produce both CXCL9/monokine induced by IFN-gamma (Mig) and CXCL10/IFN-gamma-inducible protein 10 following stimulation with IFN-gamma and clones that produce IFN-gamma-inducible protein 10 but not Mig. The Mig-deficient variants grew more aggressively as cutaneous tumors in wild-type mice than the Mig-producing tumor cells. The growth of Mig-expressing, but not Mig-deficient, tumor cells was suppressed by NK and T cell activity. Transduction of Mig-negative variants to generate constitutive tumor cell production of Mig resulted in T cell-dependent rejection of the tumors and in induction of protective tumor-specific CD8(+) T cell responses to Mig-deficient tumors. The results indicate a critical role for tumor-derived Mig in T cell-mediated responses to cutaneous fibrosarcomas and suggest the loss of Mig expression as a mechanism used by tumor cells to evade these responses.

Determination of the maturity and functionality of tumor vasculature by MRI: correlation between BOLD-MRI and DCE-MRI using P792 in experimental fibrosarcoma tumors

Using hypercapnia and carbogen as functional markers of vessel maturation and function, we compared blood oxygen level-dependent (BOLD) contrast with standard dynamic contrast-enhanced (DCE)-MRI quantitative parameters in murine fibrosarcoma. Our results show that there was no correlation between vessel maturity and contrast-agent uptake rate (K(in) (Trans)) or contrast agent efflux rate (k(ep)). In addition, DCE-MRI provided higher estimates of the fraction of functional tumor compared to BOLD-MRI. The two putative markers of regional vascular density, i.e., the magnitude of BOLD signal change during carbogen challenge (VF) and the fractional plasma volume found by DCE-MRI (V(p)), were only weakly correlated (r(2) = 0.02-0.14). Furthermore, VF showed no correlation with K(in) (Trans). A positive correlation was observed (r(2) = 0.75) between mean tumor VF and k(ep), but only when averaged over the whole tumor (which includes tumor regions completely unperfused by the gadolinium (Gd) contrast agent). This would merely reveal a relationship between perfusion status and the capacity to respond to carbogen breathing. In conclusion, characterizations of tumor microvasculature imaging using BOLD-MRI and DCE-MRI appear to be largely complementary, given the weak correlations between their corresponding derived parameters.

A highly sensitive biocompatible spin probe for imaging of oxygen concentration in tissues

The development of an injectable probe formulation, consisting of perchlorotriphenylmethyl triester radical dissolved in hexafluorobenzene, for in vivo oximetry and imaging of oxygen concentration in tissues using electron paramagnetic resonance (EPR) imaging is reported. The probe was evaluated for its oxygen sensitivity, biostability, and distribution in a radiation-induced fibrosarcoma tumor transplanted into C3H mice. Some of the favorable features of the probe are: a single narrow EPR peak (anoxic linewidth, 41 microT), high solubility in hexafluorobenzene (>12 mM), large linewidth sensitivity to molecular oxygen ( approximately 1.8 microT/mmHg), good stability in tumor tissue (half-life: 3.3 h), absence of spin-spin broadening (up to 12 mM), and lack of power saturation effects (up to 200 mW). Three-dimensional spatial and spectral-spatial (spectroscopic) EPR imaging measurements were used to visualize the distribution of the probe, as well as to obtain spatially resolved pO(2) information in the mice tumor subjected to normoxic and hyperoxic treatments. The new probe should enable unique opportunities for measurement of the oxygen concentration in tumors using EPR methods.

Stable expression of a heterogeneous gene introduced via gene targeting into the HPRT locus of human fibrosarcoma cells

To obtain a cell line that maintains stability of gene expression is important for industrial production of therapeutic proteins from recombinant cells. In this study, we attempted to improve the stability of expression of an exogenous gene by using the gene-targeting method in cultured cells. In our gene-targeting system, the green fluorescent protein (GFP) gene was used as an exogenous reporter gene targeted to the locus of the endogenous hypoxanthine phosphoribosyl transferase (HPRT) gene, which is constitutively expressed. Cell lines selected using markers of the targeting DNA were cultivated for 129 days without any drug selection, and the expression levels of GFP protein and the chromosomal structure of the gfp gene in these cell lines were evaluated. Cell lines in which gfp genes were randomly integrated into the genome showed decreased GFP expression, which resulted from loss of genes or attenuation of transcription. In contrast, cell lines in which the gfp gene was targeted to the hprt locus maintained a stable chromosomal structure and stable expression of the gfp gene, even after prolonged cultivation. These results suggest that constitutively expressed endogenous gene loci may be suitable positions for stable expression of exogenous genes, and that the gene-targeting strategy presented here may be useful for generation of cell lines for industrial protein production.

NHERF links the N-cadherin/catenin complex to the platelet-derived growth factor receptor to modulate the actin cytoskeleton and regulate cell motility

Using phage display, we identified Na+/H+ exchanger regulatory factor (NHERF)-2 as a novel binding partner for the cadherin-associated protein, beta-catenin. We showed that the second of two PSD-95/Dlg/ZO-1 (PDZ) domains of NHERF interacts with a PDZ-binding motif at the very carboxy terminus of beta-catenin. N-cadherin expression has been shown to induce motility in a number of cell types. The first PDZ domain of NHERF is known to bind platelet-derived growth factor-receptor beta (PDGF-Rbeta), and the interaction of PDGF-Rbeta with NHERF leads to enhanced cell spreading and motility. Here we show that beta-catenin and N-cadherin are in a complex with NHERF and PDGF-Rbeta at membrane ruffles in the highly invasive fibrosarcoma cell line HT1080. Using a stable short hairpin RNA system, we showed that HT1080 cells knocked down for either N-cadherin or NHERF had impaired ability to migrate into the wounded area in a scratch assay, similar to cells treated with a PDGF-R kinase inhibitor. Cells expressing a mutant NHERF that is unable to associate with beta-catenin had increased stress fibers, reduced lamellipodia, and impaired cell migration. Using HeLa cells, which express little to no PDGF-R, we introduced PDGF-Rbeta and showed that it coimmunoprecipitates with N-cadherin and that PDGF-dependent cell migration was reduced in these cells when we knocked-down expression of N-cadherin or NHERF. These studies implicate N-cadherin and beta-catenin in cell migration via PDGF-R-mediated signaling through the scaffolding molecule NHERF.

Fluence rate as a modulator of PDT mechanisms

BACKGROUND AND OBJECTIVES

Molecular oxygen in the tissue to be treated by photodynamic therapy (PDT) is critical for photodynamic cell killing. The fluence rate of PDT light delivery has been identified as an important modulator of tissue oxygenation and treatment outcome. This article provides supporting evidence for the role of fluence rate in PDT and discusses the underlying mechanisms.

STUDY DESIGN/MATERIALS AND METHODS

Intratumoral pO2 was measured polarographically in murine tumors before and during PDT light treatment using the Eppendorf pO2 Histograph. Tumor response as a function of fluence rate and fluence was also assessed in murine tumor models. Changes in vascular permeability as a function of fluence rate were determined in murine tumors by measuring tumor uptake of fluorescent beads (200 nm diameter).

RESULTS

Severe oxygen depletion is shown to occur within seconds of illumination at a fluence rate of 75 mW/cm2 in radiation-induced fibrosarcoma (RIF) tumors photosensitized with AlPcS2. This effect was reversible and consistent with photochemical oxygen depletion, which has been shown by us and others to be fluence rate dependent. It is demonstrated that fluence rate affects the PDT tumor response in the Colon 26 tumor model, high fluence rate diminishing or even totally inhibiting tumor control, low fluence rate promoting tumor control. The influence of fluence rate is not restricted to cytocidal effects, but can also be seen in sublethal conditions such as vascular permeability.

CONCLUSIONS

Fluence rate of PDT light delivery exerts far-reaching control upon treatment outcome through its oxygenation modulating properties and possibly other mechanisms yet to be identified. This has been shown to be true in the preclinical and clinical setting. Further development of in situ dosimetry will be necessary to take full advantage of these discoveries.

Fractionated and acute irradiation induced signaling in a murine tumor

The effect of fractionated doses of Co(60) gamma-irradiation (2 Gy per fraction over 5 days), as is delivered in cancer radiotherapy, was compared with acute doses of 10 and 2 Gy, in a serially transplanted mouse fibrosarcoma grown in Swiss mice. The aspects that were studied included the three major mitogen-activated protein (MAP) kinases, namely p44 MAP kinase, p38 MAP kinase, and stress-activated protein (SAP) kinase, which are known to be involved in determining the cell fate following exposure to ionizing radiation. The response of dual specificity phosphatase PAC1 which is involved in the dephosphorylation of MAP kinases was also looked at. There were significant differences in the response to different dose regimens for all the factors studied. Fractionated irradiation elicited an adaptive response with a sustained activation over 7 days of prosurvival p44 MAP kinase which was balanced by the increased activation of proapoptotic p54 SAP kinase up to 1 day post-irradiation, whereas, phosphorylated p38 MAP kinase showed a decrease at most time points. PAC1 was induced following fractionated irradiation and may be acting as a feed back regulator of p44 MAP kinase. The activation of SAP kinase after fractionated irradiation may be a stress response, whereas, constitutively activated p44 MAP kinase may play an important role in the induction of radioresistance during fractionated radiotherapy of cancer and may serve as a promising target for specific inhibitors to enhance the efficacy of radiotherapy.

Sodium butyrate alters erythropoietin glycosylation via multiple mechanisms

Recombinant human erythropoietin (rHuEPO) produced in a human kidney fibrosarcoma cell line, HT1080, was used as a model to study the effects of sodium butyrate (SB) on protein glycosylation. Treatment with 2 mM SB resulted in complex changes with respect to sugar nucleotide pools including an increase in UDP-Gal and a decrease in UDP-GlcNac. In addition, polylactosamine structures present on rHuEPO increased after SB treatment. To determine if these phenotypic changes correlated with changes in mRNA abundance, we profiled mRNA levels over a 24-h period in the presence or absence of SB using oligonucleotide microarrays. By filtering our data through a functional glycomics gene list associated with the processes of glycan degradation, glycan synthesis, and sugar nucleotide synthesis and transport we identified 26 genes with significantly altered mRNA levels. We were able to correlate the changes in message in six of these genes with measurable phenotypic changes within our system including: neu1, b3gnt6, siat4b, b3gnt1, slc17a5, and galt. Interestingly, for the two genes: cmas and gale, our measurable phenotypic changes did not correlate with changes in mRNA expression. These data demonstrate both the utility and pit falls of coupling biochemical analysis with high throughput oligonucleotide microarrays to predict how changes in cell culture environments will impact glycoprotein oligosaccharide content.

Primary fibrosarcoma of the thyroid gland--a case report

A 54-year-old woman, a teacher with a two-year history of a thyroid gland enlargement was referred to the Surgeon Ward with a preliminary cytological diagnosis of schwannoma. Histological examination of the resected tumour revealed a malignant mesenchymal tumor and a primary fibrosarcoma of the thyroid gland was ultimately confirmed. Currently, a follow-up, with further clinical investigations has been recommended.