Effects of free fatty acid receptor (FFAR) signaling on the modulation of cancer cell functions under hypoxic conditions

In the tumor environment, hypoxia promotes tumor progression, such as cancer cell growth, migration and chemoresistance. This study aimed to evaluate the roles of free fatty acid receptors (FFARs) in the regulation of cancer cell functions under hypoxic conditions, using fibrosarcoma HT1080 cells. HT1080 cells expressed FFAR1, FFAR2 and FFAR3 genes, but not FFAR4 gene. FFAR1, FFAR2 and FFAR3 expression levels in HT1080 cells cultured at 1 % O2 were elevated, compared with 21 % O2. The cell growth activities of HT1080 cells cultured at 21 % O2 were inhibited by acetic acid (AA) and propanoic acid (PA), but not 1 % O2. HT1080 cell motility was markedly reduced by culturing at 1 % O2. The cell growth and motility of HT1080 cells were enhanced by FFAR2 knockdown. The cell viability to cisplatin (CDDP) of HT1080 cells cultured at 1 % O2 was increased, compared with 21 % O2. FFAR2 knockdown suppressed the cell viability to CDDP of HT1080 cells. On the other hand, the cell motility and viability to CDDP of HT1080 cells cultured at 21 % O2 were suppressed by TUG-770. When HT1080 cells were cultured at 1 % O2, the cell motility and viability to CDDP were decreased, correlating with FFAR1 expression level. Moreover, FFAR1 knockdown increased the cell viability to CDDP of HT1080 cells cultured at 1 % O2. These results suggest that FFAR-mediated signaling plays an important role in the modulation of cellular functions of HT1080 cells under hypoxic conditions.

The Regulatory Network of CREB3L1 and Its Roles in Physiological and Pathological Conditions

CREB3 subfamily belongs to the bZIP transcription factor family and comprises five members. Normally they are located on the endoplasmic reticulum (ER) membranes and proteolytically activated through RIP (regulated intramembrane proteolysis) on Golgi apparatus to liberate the N-terminus to serve as transcription factors. CREB3L1 acting as one of them transcriptionally regulates the expressions of target genes and exhibits distinct functions from the other members of CREB3 family in eukaryotes. Physiologically, CREB3L1 involves in the regulation of bone morphogenesis, neurogenesis, neuroendocrine, secretory cell differentiation, and angiogenesis. Pathologically, CREB3L1 implicates in the modulation of osteogenesis imperfecta, low grade fibro myxoid sarcoma (LGFMS), sclerosing epithelioid fibrosarcoma (SEF), glioma, breast cancer, thyroid cancer, and tissue fibrosis. This review summarizes the upstream and downstream regulatory network of CREB3L1 and thoroughly presents our current understanding of CREB3L1 research progress in both physiological and pathological conditions with special focus on the novel findings of CREB3L1 in cancers.

RHAMM/hyaluronan inhibit β-catenin degradation, enhance downstream signaling, and facilitate fibrosarcoma cell growth

Increased hyaluronan deposition (HA) in various cancer tissues, including sarcomas, correlates with disease progression. The receptor for hyaluronic acid-mediated motility (RHAMM) expression is elevated in most human cancers. β-catenin is a critical downstream mediator of the Wnt signaling pathways, facilitating carcinogenic events characterized by deregulated cell proliferation. We previously showed that low molecular weight (LMW) HA/RHAMM/β-catenin signaling axis increases HT1080 fibrosarcoma cell growth. Here, focusing on mechanistic aspects and utilizing immunofluorescence and immunoprecipitation, we demonstrate that LMW HA treatment enhanced RHAMM intracellular localization (p ≤ 0.001) and RHAMM/β-catenin colocalization in HT1080 fibrosarcoma cells (p ≤ 0.05). Downregulating endogenous HA attenuated the association of RHAMM/β-catenin in HT1080 fibrosarcoma cells (p ≤ 0.0.01). Notably, Axin-2, the key β-catenin degradation complex component, and RHAMM were demonstrated to form a complex primarily to cell membranes, enhanced by LMW HA (p ≤ 0.01). In contrast, LMW HA attenuated the association of β-catenin and Axin-2 (p ≤ 0.05). The utilization of FH535, a Wnt signaling inhibitor, showed that LMW HA partially rescued the Wnt-dependent growth of HT1080 cells and restored the expression of Wnt/β-catenin mediators, cyclin-D1 and c-myc (p ≤ 0.05). B6FS fibrosarcoma cells with different HA metabolism do not respond to the LMW HA growth stimulus (p = NS). The present study identifies a novel LMW HA/RHAMM mechanism in a fibrosarcoma model. LMW HA regulates intracellular RHAMM expression, which acts as a scaffold protein binding β-catenin and Axin-2 at different cellular compartments to increase β-catenin expression, transcriptional activity, and fibrosarcoma growth.

Spatial and transcriptional heterogeneity of pancreatic beta cell neogenesis revealed by a time-resolved reporter system

AIMS/HYPOTHESIS

While pancreatic beta cells have been shown to originate from endocrine progenitors in ductal regions, it remains unclear precisely where beta cells emerge from and which transcripts define newborn beta cells. We therefore investigated characteristics of newborn beta cells extracted by a time-resolved reporter system.

METHODS

We established a mouse model, 'Ins1-GFP; Timer', which provides spatial information during beta cell neogenesis with high temporal resolution. Single-cell RNA-sequencing (scRNA-seq) was performed on mouse beta cells sorted by fluorescent reporter to uncover transcriptomic profiles of newborn beta cells. scRNA-seq of human embryonic stem cell (hESC)-derived beta-like cells was also performed to compare newborn beta cell features between mouse and human.

RESULTS

Fluorescence imaging of Ins1-GFP; Timer mouse pancreas successfully dissected newly generated beta cells as green fluorescence-dominant cells. This reporter system revealed that, as expected, some newborn beta cells arise close to the ducts (β^duct); unexpectedly, the others arise away from the ducts and adjacent to blood vessels (β^vessel). Single-cell transcriptomic analyses demonstrated five distinct populations among newborn beta cells, confirming spatial heterogeneity of beta cell neogenesis such as high probability of glucagon-positive β^duct, musculoaponeurotic fibrosarcoma oncogene family B (MafB)-positive β^duct and musculoaponeurotic fibrosarcoma oncogene family A (MafA)-positive β^vessel cells. Comparative analysis with scRNA-seq data of mouse newborn beta cells and hESC-derived beta-like cells uncovered transcriptional similarity between mouse and human beta cell neogenesis including microsomal glutathione S-transferase 1 (MGST1)- and synaptotagmin 13 (SYT13)-highly-expressing state.

CONCLUSIONS/INTERPRETATION

The combination of time-resolved histological imaging with single-cell transcriptional mapping demonstrated novel features of spatial and transcriptional heterogeneity in beta cell neogenesis, which will lead to a better understanding of beta cell differentiation for future cell therapy.

DATA AVAILABILITY

Raw and processed single-cell RNA-sequencing data for this study has been deposited in the Gene Expression Omnibus under accession number GSE155742.

Regulatory T cell differentiation is controlled by αKG-induced alterations in mitochondrial metabolism and lipid homeostasis

Suppressive regulatory T cell (Treg) differentiation is controlled by diverse immunometabolic signaling pathways and intracellular metabolites. Here we show that cell-permeable α-ketoglutarate (αKG) alters the DNA methylation profile of naive CD4 T cells activated under Treg polarizing conditions, markedly attenuating FoxP3+ Treg differentiation and increasing inflammatory cytokines. Adoptive transfer of these T cells into tumor-bearing mice results in enhanced tumor infiltration, decreased FoxP3 expression, and delayed tumor growth. Mechanistically, αKG leads to an energetic state that is reprogrammed toward a mitochondrial metabolism, with increased oxidative phosphorylation and expression of mitochondrial complex enzymes. Furthermore, carbons from ectopic αKG are directly utilized in the generation of fatty acids, associated with lipidome remodeling and increased triacylglyceride stores. Notably, inhibition of either mitochondrial complex II or DGAT2-mediated triacylglyceride synthesis restores Treg differentiation and decreases the αKG-induced inflammatory phenotype. Thus, we identify a crosstalk between αKG, mitochondrial metabolism and triacylglyceride synthesis that controls Treg fate.

Isoginkgetin derivative IP2 enhances the adaptive immune response against tumor antigens

The success of cancer immunotherapy relies on the induction of an immunoprotective response targeting tumor antigens (TAs) presented on MHC-I molecules. We demonstrated that the splicing inhibitor isoginkgetin and its water-soluble and non-toxic derivative IP2 act at the production stage of the pioneer translation products (PTPs). We showed that IP2 increases PTP-derived antigen presentation in cancer cells in vitro and impairs tumor growth in vivo. IP2 action is long-lasting and dependent on the CD8+ T cell response against TAs. We observed that the antigen repertoire displayed on MHC-I molecules at the surface of MCA205 fibrosarcoma is modified upon treatment with IP2. In particular, IP2 enhances the presentation of an exon-derived epitope from the tumor suppressor nischarin. The combination of IP2 with a peptide vaccine targeting the nischarin-derived epitope showed a synergistic antitumor effect in vivo. These findings identify the spliceosome as a druggable target for the development of epitope-based immunotherapies.

Microvascular Density, Endothelial Area, and Ki-67 Proliferative Index Correlate Each Other in Cat Post-Injection Fibrosarcoma

Soft tissue sarcomas are a large group of different tumor types both in humans and in animals. Among them, fibrosarcoma is the most frequent malignant mesenchymal tumoral form in cats, representing up to 28% of all cat skin tumors, while human fibrosarcoma, fortunately, only represents 5% of all sarcomas and 0.025% of the world-wide burden of tumors. This low incidence in humans leads to consideration of this group of tumoral diseases as rare, so therapeutic options are few due to the difficulty of starting clinical trials. In this context, the identification of research models for fibrosarcomas could be of great interest to deepen knowledge in this field and recognize new or possible biological pathways involved in tumor progression and metastasis. Angiogenesis is considered a fundamental scattering cause of tumor aggressiveness and progression in all forms of cancer, but only a few research parameters were developed and reported to express them quantitatively and qualitatively. The role in angiogenesis of microenvironmental stromal cells, such as fibroblasts, lymphocytes, mast cells, and macrophages, was largely demonstrated since this topic was first approached, while quantification of new vessels and their blood capacity in tumoral area is a relatively recent approach that could be well developed thanks to expertise in immunohistochemistry and image analysis. In this paper, a crossing study evaluating microvascular density (MVD), endothelial area (EA), and Ki-67 proliferative index was reported for a series of formalin-fixed and paraffin-embedded tissue samples from 99 cat patients, affected by cat post-injection fibrosarcoma, by using a till ×400 magnification light microscopy. We aim to demonstrate that cat pets may be considered a useful animal model for better studying the correspondent human diseases and we report, for the first time to our knowledge, experimental data in terms of correlation among MVD, EA, and Ki-67 strictly involved in aggressiveness and tumoral progression.

PTX3 Modulates Neovascularization and Immune Inflammatory Infiltrate in a Murine Model of Fibrosarcoma

Fibrosarcoma is an aggressive subtype of soft tissue sarcoma categorized in infantile/congenital-type and adult-type. Fibrosarcoma cells and its surrounding immune inflammatory infiltrates overexpress or induce the expression of fibroblast growth factor-2 (FGF-2) that have a crucial role in tumor progression and angiogenesis. The inflammation-associated long pentraxin 3 (PTX3) was found to reduce FGF-2-mediated angiogenesis, but its role on fibrosarcoma immune inflammatory infiltrate is still unknown. In this study, we have evaluated the PTX3 activity on immune infiltrating mast cells, macrophages and T-lymphocytes by immunohistochemistry on murine MC-TGS17-51 fibrosarcoma cells and on transgenic TgN(Tie2-hPTX3) mouse. In these fibrosarcoma models we found a reduced neovascularization and a significant decrease of inflammatory infiltrate. Indeed, we show that PTX3 reduces the level of complement 3 (C3) deposition reducing fibrosarcoma progression. In conclusion, we hypothesize that targeting fibrosarcoma microenvironment by FGF/FGFR inhibitors may improve treatment outcome.

Codelivery of a cytotoxin and photosensitiser via a liposomal nanocarrier: a novel strategy for light-triggered cytosolic release

Endosomal entrapment is a key issue for the intracellular delivery of many nano-sized biotherapeutics to their cytosolic or nuclear targets. Photochemical internalisation (PCI) is a novel light-based solution that can be used to trigger the endosomal escape of a range of bioactive agents into the cytosol leading to improved efficacy in pre-clinical and clinical studies. PCI typically depends upon the endolysosomal colocalisation of the bioactive agent with a suitable photosensitiser that is administered separately. In this study we demonstrate that both these components may be combined for codelivery via a novel multifunctional liposomal nanocarrier, with a corresponding increase in the biological efficacy of the encapsulated agent. As proof of concept, we show here that the cytotoxicity of the 30 kDa protein toxin, saporin, in MC28 fibrosarcoma cells is significantly enhanced when delivered via a cell penetrating peptide (CPP)-modified liposome, with the CPP additionally functionalised with a photosensitiser that is targeted to endolysosomal membranes. This innovation opens the way for the efficient delivery of a range of biotherapeutics by the PCI approach, incorporating a clinically proven liposome delivery platform and using bioorthogonal ligation chemistries to append photosensitisers and peptides of choice.

Peroxiredoxin 1 (PRDX1) Suppresses Progressions and Metastasis of Osteosarcoma and Fibrosarcoma of Bone

BACKGROUND Osteosarcoma and fibrosarcoma are malignant tumors with poor prognosis. Peroxiredoxin 1 (PRDX1) is considered to prevent tumors in many malignances. However, few studies have focused on the functions of PRDX1 in osteosarcoma and fibrosarcoma. MATERIAL AND METHODS PRDX1 mRNA in tumors and adjacent tissues of 32 osteosarcoma patients and 16 fibrosarcoma patients was extracted and measured. Proliferation and invasion of MG63 and HT1080 cell lines after silencing or overexpressing PRDX1 were used to detect the role of PRDX1 in metastasis of osteosarcoma and fibrosarcoma. RESULTS PRDX1 mRNA level was lower in tumor tissues than in adjacent tissues of osteosarcoma (F=50.105) and fibrosarcoma (F=28.472) patients, both significantly (P<0.05). Silencing PRDX1 promoted proliferation of MG63 and HT1080 cells, while overexpressing PRDX1 suppressed proliferation after 24 h, 48 h, and 72 h, compared to the control group, both significantly (P<0.05). Silencing PRDX1 increased invasive cells of MG63 (F=246.218) and HT1080 (F=245.602), while overexpressing PRDX1 decreased invasive cells of both, compared to the control, and the difference was significant (P<0.05). CONCLUSIONS PRDX1 expression is low in osteosarcoma and fibrosarcoma tumors. PRDX1 suppressed the progression and metastasis of osteosarcoma and fibrosarcoma cells.

Oxygen microbubbles improve radiotherapy tumor control in a rat fibrosarcoma model - A preliminary study

Cancer affects 39.6% of Americans at some point during their lifetime. Solid tumor microenvironments are characterized by a disorganized, leaky vasculature that promotes regions of low oxygenation (hypoxia). Tumor hypoxia is a key predictor of poor treatment outcome for all radiotherapy (RT), chemotherapy and surgery procedures, and is a hallmark of metastatic potential. In particular, the radiation therapy dose needed to achieve the same tumor control probability in hypoxic tissue as in normoxic tissue can be up to 3 times higher. Even very small tumors (<2-3 mm3) comprise 10-30% of hypoxic regions in the form of chronic and/or transient hypoxia fluctuating over the course of seconds to days. We investigate the potential of recently developed lipid-stabilized oxygen microbubbles (OMBs) to improve the therapeutic ratio of RT. OMBs, but not nitrogen microbubbles (NMBs), are shown to significantly increase dissolved oxygen content when added to water in vitro and increase tumor oxygen levels in vivo in a rat fibrosarcoma model. Tumor control is significantly improved with OMB but not NMB intra-tumoral injections immediately prior to RT treatment and effect size is shown to depend on initial tumor volume on RT treatment day, as expected.

Perfusion-based fluorescence imaging method delineates diverse organs and identifies multifocal tumors using generic near-infrared molecular probes

Rapid detection of multifocal cancer without the use of complex imaging schemes will improve treatment outcomes. In this study, dynamic fluorescence imaging was used to harness differences in the perfusion kinetics of near-infrared (NIR) fluorescent dyes to visualize structural characteristics of different tissues. Using the hydrophobic nontumor-selective NIR dye cypate, and the hydrophilic dye LS288, a high tumor-to-background contrast was achieved, allowing the delineation of diverse tissue types while maintaining short imaging times. By clustering tissue types with similar perfusion properties, the dynamic fluorescence imaging method identified secondary tumor locations when only the primary tumor position was known, with a respective sensitivity and specificity of 0.97 and 0.75 for cypate, and 0.85 and 0.81 for LS288. Histological analysis suggests that the vasculature in the connective tissue that directly surrounds the tumor was a major factor for tumor identification through perfusion imaging. Although the hydrophobic dye showed higher specificity than the hydrophilic probe, use of other dyes with different physical and biological properties could further improve the accuracy of the dynamic imaging platform to identify multifocal tumors for potential use in real-time intraoperative procedures.

D2A-Ala peptide derived from the urokinase receptor exerts anti-tumoural effects in vitro and in vivo

D2A-Ala is a synthetic peptide that has been created by introducing mutations in the original D2A sequence, ¹³⁰IQEGEEGRPKDDR¹⁴² of human urokinase receptor (uPAR). In vitro, D2A-Ala peptide displays strong anti-tumoural properties inhibiting EGF-induced chemotaxis, invasion and proliferation of a human fibrosarcoma cell line, HT 1080, and a human colorectal adenocarcinoma cell line, HT 29. D2A-Ala exerts its effects by preventing EGF receptor (EGFR) phosphorylation. To test D2A-Ala in vivo, this peptide was PEGylated generating polyethyleneglycol (PEG)-D2A-Ala peptide. PEGylation did not alter the inhibitory properties of D2A-Ala. Human tumour xenografts in the immunodeficient nude mice using HT 1080 and HT 29 cell lines showed that PEG-D2A-Ala significantly prevents tumour growth decreasing size, weight and density of tumours. The most efficient doses of the peptide were 5 and 10 mg/kg, thereby relevant for possible development of the peptide into a drug against cancer in particular tumours expressing EGFR.

Abdominopelvic and Retroperitoneal Low-Grade Fibromyxoid Sarcoma: A Clinicopathologic Study of 13 Cases

OBJECTIVES

Low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor often arising in the lower extremities. Only rare examples in the abdominal cavity, pelvis, and retroperitoneum have been reported.

METHODS

cases of abdominopelvic and retroperitoneal LGFMS were retrieved. MUC4, Actin, ALK, β-catenin, desmin, DOG1, KIT, S100 protein, and STAT6 testing was performed, and a subset was tested for FUS rearrangement.

RESULTS

Sites included intra-abdominal/abdominal wall (four cases), retroperitoneum (three cases), pelvis (three cases), small bowel (two cases), and kidney (one case) (median size, 15 cm; age range, 5-61 years). Tumors harbored spindled cells with mild to moderate atypia, displaying alternating myxoid nodules and hyalinized areas. All cases were positive for MUC4, and five (of five) cases tested harbored FUS rearrangement. Variable positivity for DOG1 (four of 10) and actin (two of 10) was identified. Six tumors recurred, and one patient developed metastasis.

CONCLUSION

LGFMS arising in these central locations exhibits similar clinicopathologic features to its counterpart in the extremities. LGFMS at these sites may show limited immunoreactivity for DOG1 and actin.

Cell Type-Specific Modulation of Cobalamin Uptake by Bovine Serum

Tracking cellular ⁵⁷Co-labelled cobalamin (⁵⁷Co-Cbl) uptake is a well-established method for studying Cbl homeostasis. Previous studies established that bovine serum is not generally permissive for cellular Cbl uptake when used as a supplement in cell culture medium, whereas supplementation with human serum promotes cellular Cbl uptake. The underlying reasons for these differences are not fully defined. In the current study we address this question. We extend earlier observations by showing that fetal calf serum inhibits cellular ⁵⁷Co-Cbl uptake by HT1080 cells (a fibrosarcoma-derived fibroblast cell line). Furthermore, we discovered that a simple heat-treatment protocol (95°C for 10 min) ameliorates this inhibitory activity for HT1080 cell ⁵⁷Co-Cbl uptake. We provide evidence that the very high level of haptocorrin in bovine serum (as compared to human serum) is responsible for this inhibitory activity. We suggest that bovine haptocorrin competes with cell-derived transcobalamin for Cbl binding, and that cellular Cbl uptake may be minimised in the presence of large amounts of bovine haptocorrin that are present under routine in vitro cell culture conditions. In experiments conducted with AG01518 cells (a neonatal foreskin-derived fibroblast cell line), overall cellular ⁵⁷Co-Cbl uptake was 86% lower than for HT1080 cells, cellular TC production was below levels detectable by western blotting, and heat treatment of fetal calf serum resulted in only a modest increase in cellular ⁵⁷Co-Cbl uptake. We recommend a careful assessment of cell culture protocols should be conducted in order to determine the potential benefits that heat-treated bovine serum may provide for in vitro studies of mammalian cell lines.

Integrin-α10 Dependency Identifies RAC and RICTOR as Therapeutic Targets in High-Grade Myxofibrosarcoma

Myxofibrosarcoma is a common mesenchymal malignancy with complex genomics and heterogeneous clinical outcomes. Through gene-expression profiling of 64 primary high-grade myxofibrosarcomas, we defined an expression signature associated with clinical outcome. The gene most significantly associated with disease-specific death and distant metastasis was ITGA10 (integrin-α10). Functional studies revealed that myxofibrosarcoma cells strongly depended on integrin-α10, whereas normal mesenchymal cells did not. Integrin-α10 transmitted its tumor-specific signal via TRIO and RICTOR, two oncoproteins that are frequently co-overexpressed through gene amplification on chromosome 5p. TRIO and RICTOR activated RAC/PAK and AKT/mTOR to promote sarcoma cell survival. Inhibition of these proteins with EHop-016 (RAC inhibitor) and INK128 (mTOR inhibitor) had antitumor effects in tumor-derived cell lines and mouse xenografts, and combining the drugs enhanced the effects. Our results demonstrate the importance of integrin-α10/TRIO/RICTOR signaling for driving myxofibrosarcoma progression and provide the basis for promising targeted treatment strategies for patients with high-risk disease.

SIGNIFICANCE

Identifying the molecular pathogenesis for myxofibrosarcoma progression has proven challenging given the highly complex genomic alterations in this tumor type. We found that integrin-α10 promotes tumor cell survival through activation of TRIO-RAC-RICTOR-mTOR signaling, and that inhibitors of RAC and mTOR have antitumor effects in vivo, thus identifying a potential treatment strategy for patients with high-risk myxofibrosarcoma. Cancer Discov; 6(10); 1148-65. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 1069.

Very low doses of ionizing radiation and redox associated modifiers affect survivin-associated changes in radiation sensitivity

Exposure of cells to a dose of ionizing radiation as low as 5mGy can induce changes in radiation sensitivity expressed by cells exposed to subsequent higher doses at later times. This is referred to as an adaptive effect. We describe a unique survivin-associated adaptive response in which increased radiation resistance or sensitization of cells can be induced by exposure to 5mGy or to the reactive oxygen species (ROS) generating drug Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a naturally occurring anthraquinone. The purpose of this study was to determine the role of ROS generating processes in affecting both the intracellular localization of the inhibitor of apoptosis protein survivin and its subsequent effect on radiation response in the presence or absence of the anti-oxidant N-acetyl-L-cysteine (NAC). Experiments were performed using two well characterized murine sarcomas: SA-NH p53 wild-type (WT) and FSa p53 mutant (Mut), grown either in culture or as solid tumors in the right hind legs of C3H mice. Doses of 5mGy or 50μM Emodin were used to induce changes in the response of these tumor cells to higher radiation exposures using a multi-dosing paradigm. Effects on radiation sensitivity were determined for SA-NH and FSa cells as a function of survivin translocation either to the cytoplasm or nucleus in the presence or absence of 10mM NAC treatment. In vitro survival assays (2Gy per fraction, two once daily fractions) and tumor growth delay (TGD) (5Gy per fraction, five once daily fractions) studies were performed. Intracellular localization of survivin was determined by enzyme-linked immunosorbent assay (ELISA) and correlated to survival response and treatment conditions. 2Gy alone had no effect on intracellular translocation of survivin. When preceded 15min earlier by 5mGy or Emodin exposures, survivin became elevated in the cytoplasm of p53 WT SA-NH as compared to the nuclei of p53 Mut FSa cells. SA-NH cells transfected with p53 small interfering RNA (siRNA), in contrast, responded similarly to p53 Mut FSa cells by becoming more radiation sensitive if exposed to 5mGy prior to each 2Gy irradiation. In contrast to their respective responses to five once daily 5Gy fractions, SA-NH tumors were protected by 5mGy exposures administered 15min prior to each daily 5Gy dose as evidenced by a more rapid growth (1.9 day decrease in TGD, P=0.032), while FSa tumors were sensitized, growing at a much slower rate (4.5 day increase in TGD, P<0.001). Exposure of SA-NH and FSa tumor cells to 10mM NAC inhibited the ability of 5mGy and Emodin to induce intracellular translocation of survivin and the corresponding altered adaptive survival response. The survivin-associated adaptive response can be induced following a multi-dosing scheme in which very low radiation doses are followed shortly thereafter by higher doses consistent with a standard image guided radiotherapy protocol that is currently widely used in the treatment of cancer. While induced by exposure to ROS generating stresses, the ultimate expression of changes in radiation response is dependent upon the bi-functionality of the tumor associated protein survivin and its intracellular translocation.

Assessing pH and Oxygenation in Cryotherapy-induced Cytotoxicity and Tissue Response to Freezing

The microenvironmental pH and oxygenation is known to influence tumor cell response to heat, radiation, photodynamic and even chemotherapy. We have studied the previously untested influence of acidity and hypoxia on tumor and endothelial cell sensitivity to freezing. In addition, we have measured changes in oxygenation in vivo in murine FSaII fibrosarcomas after freeze injury. A low pH or low oxygenation environment was found to increase the sensitivity of tumor and endothelial cells to freezing at −20° C or −40° C in vitro. However, low pH and low oxygenation combined did not further increase cryosensitivity of the cells. In vivo, tumor oxygenation after freeze injury was studied immediately or 1–3 days after a standard freezing protocol was applied to FSaII tumors ranging from 250–500 mm3 grown in the rear-limb of C3H mice. Tumor oxygenation at the edge of the iceball was found to transiently increase 1–2 hours after freezing. At 1–3 days after freezing, a treatment that delayed FSaII tumor growth by approximately 1.5-fold, the mean tumor oxygenation was significantly increased by up to 2.5-fold from a control level of 5 mmHg partial pressure of oxygen (pO2), especially at the periphery of the tumor. We conclude that manipulation of pH or oxygenation has potential to increase the anti-tumor effects of minimally invasive cryosurgical techniques. Furthermore, the dynamic changes in oxygenation after freeze injury in vivo suggests value in combining cryotherapy with treatments dependent on oxygenation levels. Ultimately, these may be routes to more reliable treatment response with fewer recurrences.

[The Role of Membrane-Bound Heat Shock Proteins Hsp90 in Migration of Tumor Cells in vitro and Involvement of Cell Surface Heparan Sulfate Proteoglycans in Protein Binding to Plasma Membrane]

Heat shock protein Hsp90, detected in the extracellular space and on the membrane of cells, plays an important role in cell motility, migration, invasion and metastasis of tumor cells. At present, the functional role and molecular mechanisms of Hsp90 binding to plasma membrane are not elucidated. Using isoform-specific antibodies against Hsp90, Hsp9α and Hsp90β, we showed that membrane-bound Hsp90α and Hsp90β play a significant role in migration of human fibrosarcoma (HT1080) and glioblastoma (A-172) cells in vitro. Disorders of sulfonation of cell heparan sulfates, cleavage of cell heparan. sulfates by heparinase I/III as well as treatment of cells with heparin lead to an abrupt reduction in the expression level of Hsp90 isoforms. Furthermore, heparin significantly inhibits tumor cell migration. The results obtained demonstrate that two isoforms of membrane-bound Hsp90 are involved in migration of tumor cells in vitro and that cell surface heparan sulfate proteoglycans play a pivotal role in the "anchoring" of Hsp90α and Hsp90β to the plasma membrane.

PRIMARY FIBROSARCOMA OF THE THYROID GLAND: CASE REPORT

Due to progressive dyspnea, a male patient aged 59 underwent medical examination in 2003 in a local hospital. Neck ultrasound and fine-needle aspiration biopsy (FNAB) of a suspect lesion in the thyroid gland revealed the presence of a malignant neoplasm, i.e. mesenchymal tumor. Immunocytochemistry for epithelial membrane antigen, chromogranin A and leukocyte common antigen (CD45) was negative, while vimentin and S-100 were positive. The patient was referred to a university hospital center, where further oncologic work-up was done. Neck ultrasound revealed a tumor in the left lobe of the thyroid, with extension to the aortic arch. After repeated FNAB, cytologic diagnosis of primary thyroid fibrosarcoma was established. Due to the locally advanced and consequently inoperable disease, primary radiotherapy to the neck region (64 Gy in 32 fractions) was applied, followed by 6 cycles of chemotherapy with doxorubicin. After completion of therapy, computed tomography scan demonstrated significant regression of primary disease, but it was still not amenable to surgical treatment. Thus, the decision of the oncology board was active surveillance of the patient. During 9-year follow up, no signs of progression or activity of the disease were found.

Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging

Ultrasound molecular imaging utilizes targeted microbubbles to bind to vascular targets such as integrins, selectins and other extracellular binding domains. After binding, these microbubbles are typically imaged using low pressures and multi-pulse imaging sequences. In this article, we present an alternative approach for molecular imaging using ultrasound that relies on superharmonic signals produced by microbubble contrast agents. Bound bubbles were insonified near resonance using a low frequency (4 MHz) element and superharmonic echoes were received at high frequencies (25-30 MHz). Although this approach was observed to produce declining image intensity during repeated imaging in both in vitro and in vivo experiments because of bubble destruction, the feasibility of superharmonic molecular imaging was demonstrated for transmit pressures, which are sufficiently high to induce shell disruption in bound microbubbles. This approach was validated using microbubbles targeted to the αvβ3 integrin in a rat fibrosarcoma model (n = 5) and combined with superharmonic images of free microbubbles to produce high-contrast, high-resolution 3-D volumes of both microvascular anatomy and molecular targeting. Image intensity over repeated scans and the effect of microbubble diameter were also assessed in vivo, indicating that larger microbubbles yield increased persistence in image intensity. Using ultrasound-based acoustic angiography images rather than conventional B-mode ultrasound to provide the underlying anatomic information facilitates anatomic localization of molecular markers. Quantitative analysis of relationships between microvasculature and targeting information indicated that most targeting occurred within 50 μm of a resolvable vessel (>100 μm diameter). The combined information provided by these scans may present new opportunities for analyzing relationships between microvascular anatomy and vascular targets, subject only to limitations of the current mechanically scanned system and microbubble persistence to repeated imaging at moderate mechanical indices.

An Active 32-kDa Cathepsin L Is Secreted Directly from HT 1080 Fibrosarcoma Cells and Not via Lysosomal Exocytosis

Cathepsin L [EC 3.4.22.15] is secreted via lysosomal exocytosis by several types of cancer cells, including prostate and breast cancer cells. We previously reported that human cultured fibrosarcoma (HT 1080) cells secrete cathepsin L into the medium; this secreted cathepsin is 10-times more active than intracellular cathepsin. This increased activity was attributed to the presence of a 32-kDa cathepsin L in the medium. The aim of this study was to examine how this active 32-kDa cathepsin L is secreted into the medium. To this end, we compared the secreted active 32-kDa cathepsin L with lysosomal cathepsin L by using a novel gelatin zymography technique that employs leupeptin. We also examined the glycosylation and phosphorylation status of the proteins by using the enzymes endoglycosidase H [EC 3.2.1.96] and alkaline phosphatase [EC 3.1.3.1]. Strong active bands corresponding to the 32-kDa and 34-kDa cathepsin L forms were detected in the medium and lysosomes, respectively. The cell extract exhibited strong active bands for both forms. Moreover, both forms were adsorbed onto a concanavalin A-agarose column. The core protein domain of both forms had the same molecular mass of 30 kDa. The 32-kDa cathepsin L was phosphorylated, while the 34-kDa lysosomal form was dephosphorylated, perhaps because of the lysosomal marker enzyme, acid phosphatase. These results suggest that the active 32-kDa form does not enter the lysosomes. In conclusion, our results indicate that the active 32-kDa cathepsin L is secreted directly from the HT 1080 cells and not via lysosomal exocytosis.

Deletions in the cytoplasmic domain of iRhom1 and iRhom2 promote shedding of the TNF receptor by the protease ADAM17

The protease ADAM17 (a disintegrin and metalloproteinase 17) catalyzes the shedding of various transmembrane proteins from the surface of cells, including tumor necrosis factor (TNF) and its receptors. Liberation of TNF receptors (TNFRs) from cell surfaces can dampen the cellular response to TNF, a cytokine that is critical in the innate immune response and promotes programmed cell death but can also promote sepsis. Catalytically inactive members of the rhomboid family of proteases, iRhom1 and iRhom2, mediate the intracellular transport and maturation of ADAM17. Using a genetic screen, we found that the presence of either iRhom1 or iRhom2 lacking part of their extended amino-terminal cytoplasmic domain (herein referred to as ΔN) increases ADAM17 activity, TNFR shedding, and resistance to TNF-induced cell death in fibrosarcoma cells. Inhibitors of ADAM17, but not of other ADAM family members, prevented the effects of iRhom-ΔN expression. iRhom1 and iRhom2 were functionally redundant, suggesting a conserved role for the iRhom amino termini. Cells from patients with a dominantly inherited cancer susceptibility syndrome called tylosis with esophageal cancer (TOC) have amino-terminal mutations in iRhom2. Keratinocytes from TOC patients exhibited increased TNFR1 shedding compared with cells from healthy donors. Our results explain how loss of the amino terminus in iRhom1 and iRhom2 impairs TNF signaling, despite enhancing ADAM17 activity, and may explain how mutations in the amino-terminal region contribute to the cancer predisposition syndrome TOC.

mTORC2 Balances AKT Activation and eIF2α Serine 51 Phosphorylation to Promote Survival under Stress

The mTOR nucleates two complexes, namely mTOR complex 1 and 2 (mTORC1 and mTORC2), which are implicated in cell growth, survival, metabolism, and cancer. Phosphorylation of the α-subunit of translation initiation factor eIF2 at serine 51 (eIF2αS51P) is a key event of mRNA translation initiation and a master regulator of cell fate during cellular stress. Recent studies have implicated mTOR signaling in the stress response, but its connection to eIF2αS51P has remained unclear. Herein, we report that genetic as well as catalytic inhibition of mTORC2 induces eIF2αS51P. On the other hand, the allosteric inhibitor rapamycin induces eIF2αS51P through pathways that are independent of mTORC1 inactivation. Increased eIF2αS51P by impaired mTORC2 depends on the inactivation of AKT, which primes the activation of the endoplasmic reticulum (ER)-resident kinase PERK/PEK. The biologic function of eIF2αS51P was characterized in tuberous sclerosis complex (TSC)-mutant cells, which are defective in mTORC2 and AKT activity. TSC-mutant cells exhibit increased PERK activity, which is downregulated by the reconstitution of the cells with an activated form of AKT1. Also, TSC-mutant cells are increasingly susceptible to ER stress, which is reversed by AKT1 reconstitution. The susceptibility of TSC-mutant cells to ER stress is further enhanced by the pharmacologic inhibition of PERK or genetic inactivation of eIF2αS51P. Thus, the PERK/eIF2αS51P arm is an important compensatory prosurvival mechanism, which substitutes for the loss of AKT under ER stress.

IMPLICATIONS

A novel mechanistic link between mTOR function and protein synthesis is identified in TSC-null tumor cells under stress and reveals potential for the development of antitumor treatments with stress-inducing chemotherapeutics.

Prognostic impact of CD109 expression in myxofibrosarcoma

BACKGROUND

CD109, a TGF-β co-receptor, is reported to be preferentially expressed during the early stages of tumorigenesis in several carcinoma types. Myxofibrosarcoma is one of the most common soft-tissue sarcomas found in elderly patients. This study aimed to elucidate the impact of CD109 expression in myxofibrosarcoma on prognosis and recurrence.

METHODS

Immunohistochemical staining for CD109 was performed on archival specimens from 37 patients. The Fisher exact test was used to evaluate association between CD109 expression and other clinicopathological features. Survival analysis was performed using Kaplan-Meier curves, and the prognostic significance was evaluated using the log-rank test. Multivariate analysis of factors was performed using Cox regression analysis.

RESULTS

CD109 overexpression was significantly associated with surgical stage and distant metastasis (P = 0.00499, and 0.011, respectively). The frequency of CD109 overexpression was approximately 10% and CD109 overexpression was significantly associated with decreased overall survival (P = 0.004). Five-year overall survival rates 77% and 0% for CD109-negative and CD109-positive patients, respectively. In multivariate analysis, CD109 overexpression was the only independent risk factor for poor outcome (P = 0.02; hazard ratio, 10.64; 95% confidence interval, 1.47-76.91).

CONCLUSIONS

Immunohistochemical CD109 expression in myxofibrosarcoma was associated with poor prognosis.

The DNA hypomethylating agent, 5-aza-2'-deoxycytidine, enhances tumor cell invasion through a transcription-dependent modulation of MMP-1 expression in human fibrosarcoma cells

In diseases such as cancer, cells need to degrade the extracellular matrix (ECM) and therefore require high protease levels. Thus, aberrant tissue degradation is associated to matrix metalloproteinases (MMPs) overexpression resulting from different mechanisms including epigenetic events. One of the most characterized epigenetic mechanisms is DNA methylation causing changes in chromatin conformation, thereby decreasing the accessibility to the transcriptional machinery and resulting in a robust gene silencing. Modulation of DNA methylation by DNA hypomethylating agents such as 5-aza-2'-deoxycytidine (5-azadC) is widely used in epigenetic anticancer treatments. Here, we focus on the effects of this drug on the expression level of MMP-1, -2, and -9 in human HT1080 fibrosarcoma cells. We demonstrate that 5-azadC increases MMP expression at both mRNA and protein levels, and promotes invasion potential of HT1080 cells. Using broad-spectrum and specific MMP inhibitors, we establish that MMP-1, but not MMP-2 and -9, plays a key role in 5-azadC-enhanced cell invasion. We show that 5-azadC induces MMP-1 expression through a transcriptional mechanism without affecting MMP-1 promoter methylation status. Finally, we demonstrate that 5-azadC treatment increases the nuclear levels of Sp1 and Sp3 transcription factors, and modulates their recruitment to the MMP-1 promoter, resulting in chromatin remodeling associated to 5-azadC-induced MMP-1 expression. All together, our data indicate that the hypomethylating agent 5-azadC modulates, mainly via Sp1 recruitment, MMP-1 expression resulting in an increased invasive potential of HT1080 cells.

Galangin and kaempferol suppress phorbol-12-myristate-13-acetate-induced matrix metalloproteinase-9 expression in human fibrosarcoma HT-1080 cells

Matrix metalloproteinase (MMP)-9 degrades type IV collagen in the basement membrane and plays crucial roles in several pathological implications, including tumorigenesis and inflammation. In this study, we analyzed the effect of flavonols on MMP-9 expression in phorbol-12-myristate-13-acetate (PMA)-induced human fibrosarcoma HT-1080 cells. Galangin and kaempferol efficiently decreased MMP-9 secretion, whereas fisetin only weakly decreased its secretion. Galangin and kaempferol did not affect cell viability at concentrations up to 30 μM. Luciferase reporter assays showed that galangin and kaempferol decrease transcription of MMP-9 mRNA. Moreover, galangin and kaempferol strongly reduce IκBα phosphorylation and significantly decrease JNK phosphorylation. These results indicate that galangin and kaempferol suppress PMA-induced MMP-9 expression by blocking activation of NF-κB and AP-1. Therefore, these flavonols could be used as chemopreventive agents to lower the risk of diseases involving MMP-9.

Role of non-genomic androgen signalling in suppressing proliferation of fibroblasts and fibrosarcoma cells

The functions of androgen receptor (AR) in stromal cells are still debated in spite of the demonstrated importance of these cells in organ development and diseases. Here, we show that physiological androgen concentration (10 nM R1881 or DHT) fails to induce DNA synthesis, while it consistently stimulates cell migration in mesenchymal and transformed mesenchymal cells. Ten nanomolar R1881 triggers p27 Ser10 phosphorylation and its stabilization in NIH3T3 fibroblasts. Activation of Rac and its downstream effector DYRK 1B is responsible for p27 Ser10 phosphorylation and cell quiescence. Ten nanomolar androgen also inhibits transformation induced by oncogenic Ras in NIH3T3 fibroblasts. Overexpression of an AR mutant unable to interact with filamin A, use of a small peptide displacing AR/filamin A interaction, and filamin A knockdown indicate that the androgen-triggered AR/filamin A complex regulates the pathway leading to p27 Ser10 phosphorylation and cell cycle arrest. As the AR/filamin A complex is also responsible for migration stimulated by 10 nM androgen, our report shows that the androgen-triggered AR/filamin A complex controls, through Rac 1, the decision of cells to halt cell cycle and migration. This study reveals a new and unexpected role of androgen/AR signalling in coordinating stromal cell functions.

Histidine-rich glycoprotein uptake and turnover is mediated by mononuclear phagocytes

Histidine-rich glycoprotein (HRG) is implicated in tumor growth and metastasis by regulation of angiogenesis and inflammation. HRG is produced by hepatocytes and carried to tissues via the circulation. We hypothesized that HRG's tissue distribution and turnover may be mediated by inflammatory cells. Biodistribution parameters were analyzed by injection of radiolabeled, bioactive HRG in the circulation of healthy and tumor-bearing mice. ¹²⁵I-HRG was cleared rapidly from the blood and taken up in tissues of healthy and tumor-bearing mice, followed by degradation, to an increased extent in the tumor-bearing mice. Steady state levels of HRG in the circulation were unaffected by the tumor disease both in murine tumor models and in colorectal cancer (CRC) patients. Importantly, stromal pools of HRG, detected in human CRC microarrays, were associated with inflammatory cells. In agreement, microautoradiography identified ¹²⁵I-HRG in blood vessels and on CD45-positive leukocytes in mouse tissues. Moreover, radiolabeled HRG bound in a specific, heparan sulfate-independent manner, to differentiated human monocytic U937 cells in vitro. Suppression of monocyte differentiation by systemic treatment of mice with anti-colony stimulating factor-1 neutralizing antibodies led to reduced blood clearance of radiolabeled HRG and to accumulation of endogenous HRG in the blood. Combined, our data show that mononuclear phagocytes have specific binding sites for HRG and that these cells are essential for uptake of HRG from blood and distribution of HRG in tissues. Thereby, we confirm and extend our previous report that inflammatory cells mediate the effect of HRG on tumor growth and metastatic spread.

Cytoplasmic expression of Wilms tumor transcription factor-1 (WT1): a useful immunomarker for young-type fibromatoses and infantile fibrosarcoma

There is increasing evidence that Wilms' tumor transcription factor-1 (WT1) is expressed in the cytoplasm of neoplastic cells from different benign and malignant tumors. Only a few studies on WT1 cytoplasmic immunolocalization are available in pediatric tumors. The aim of the present study was to investigate immunohistochemically the expression and distribution of WT1 in a large series of soft tissue fibroblastic/myofibroblastic lesions occurring in children and adolescents. Notably WT1 was not expressed in nodular fasciitis and desmoid-type (adult) fibromatosis, while it stained diffusely and strongly in several infantile-type fibromatoses, such as fibrous hamartoma of infancy, myofibroma/myofibromatosis, and lipofibromatosis. Interestingly, WT1 cytoplasmic expression was also found in all cases (10/10) of infantile fibrosarcomas examined. The present study shows that a diffuse WT1 cytoplasmic expression is of complementary diagnostic value to conventional myofibroblastic markers (α-smooth muscle actin; desmin) in confirming diagnosis of young-type fibromatoses or infantile fibrosarcoma and in ruling out both desmoid-type fibromatoses and nodular fasciitis. WT1 cytoplasmic expression in infantile fibrosarcoma is a novel finding which could be exploitable as an immunomarker for this tumor. Although highly sensitive, WT1 cytoplasmic immunostaining is not specific for infantile fibrosarcoma, and thus it should be evaluated in the context of a wide immunohistochemical panel when pathologists are dealing with spindle cell lesions of soft tissues in children and adolescents. Accordingly we recommend that a correct diagnosis of fibroblastic/myofibroblastic soft tissue lesion in pediatric patients is usually achieved on the basis of a careful correlation of morphological and immunohistochemical findings in the appropriate clinical context. The different cellular localization of WT1, namely nuclear, cytoplasmic or nucleo-cytoplasmic, in different benign and malignant tumors supports the hypothesis that this transcription factor plays a complex role in tumorigenesis, likely as a chameleon protein functioning as either a tumor suppressor gene or an oncogene, depending on cellular context.

Tumour cells expressing single VEGF isoforms display distinct growth, survival and migration characteristics

Vascular endothelial growth factor-A (VEGF) is produced by most cancer cells as multiple isoforms, which display distinct biological activities. VEGF plays an undisputed role in tumour growth, vascularisation and metastasis; nevertheless the functions of individual isoforms in these processes remain poorly understood. We investigated the effects of three main murine isoforms (VEGF188, 164 and 120) on tumour cell behaviour, using a panel of fibrosarcoma cells we developed that express them individually under endogenous promoter control. Fibrosarcomas expressing only VEGF188 (fs188) or wild type controls (fswt) were typically mesenchymal, formed ruffles and displayed strong matrix-binding activity. VEGF164- and VEGF120-producing cells (fs164 and fs120 respectively) were less typically mesenchymal, lacked ruffles but formed abundant cell-cell contacts. On 3D collagen, fs188 cells remained mesenchymal while fs164 and fs120 cells adopted rounded/amoeboid and a mix of rounded and elongated morphologies respectively. Consistent with their mesenchymal characteristics, fs188 cells migrated significantly faster than fs164 or fs120 cells on 2D surfaces while contractility inhibitors accelerated fs164 and fs120 cell migration. VEGF164/VEGF120 expression correlated with faster proliferation rates and lower levels of spontaneous apoptosis than VEGF188 expression. Nevertheless, VEGF188 was associated with constitutively active/phosphorylated AKT, ERK1/2 and Stat3 proteins. Differences in proliferation rates and apoptosis could be explained by defective signalling downstream of pAKT to FOXO and GSK3 in fs188 and fswt cells, which also correlated with p27/p21 cyclin-dependent kinase inhibitor over-expression. All cells expressed tyrosine kinase VEGF receptors, but these were not active/activatable suggesting that inherent differences between the cell lines are governed by endogenous VEGF isoform expression through complex interactions that are independent of tyrosine kinase receptor activation. VEGF isoforms are emerging as potential biomarkers for anti-VEGF therapies. Our results reveal novel roles of individual isoforms associated with cancer growth and metastasis and highlight the importance of understanding their diverse actions.

Synthesis and biological evaluation of 177Lu-DOTA-porphyrin conjugate: a potential agent for targeted tumor radiotherapy detection

A novel unsymmetrically substituted water soluble porphyrin derivative namely, 5-(p-amino-propylene--oxyphenyl)-10,15,20-tris-(p-carboxy-methyl-ene-oxyphenyl)porphyrin was synthesized and coupled with a bifunctional chelating agent, viz. p-NCS-benzyl-DOTA (p-isothiocyanatobenzyl-1,4,7,10-tetra-aza-cyclodo-decane-1,4,7,10-tetra-acetic acid) for developing a suitable conjugate for use in targeted tumor therapy. The porphyrin-p-NCS-benzyl-DOTA conjugate was radiolabeled with 177Lu in good radiolabeling yield. Biodistribution studies performed in Swiss mice bearing fibrosarcoma tumors revealed high tumor uptake (5.33±1.11% injected activity per gm of tumor) within 30 min post-injection. The complex exhibited favorable tumor to blood and tumor to muscle ratios at various post-administration time points. Fast clearance of the non-accumulated activity was observed mostly through the renal pathway. Scintigraphic imaging studies performed in Swiss mice bearing fibrosarcoma tumors also exhibited selective accumulation of activity in the tumor.

Oral tolerance to cancer can be abrogated by T regulatory cell inhibition

Oral administration of tumour cells induces an immune hypo-responsiveness known as oral tolerance. We have previously shown that oral tolerance to a cancer is tumour antigen specific, non-cross-reactive and confers a tumour growth advantage. We investigated the utilisation of regulatory T cell (Treg) depletion on oral tolerance to a cancer and its ability to control tumour growth. Balb/C mice were gavage fed homogenised tumour tissue--JBS fibrosarcoma (to induce oral tolerance to a cancer), or PBS as control. Growth of subcutaneous JBS tumours were measured; splenic tissue excised and flow cytometry used to quantify and compare systemic Tregs and T effector (Teff) cell populations. Prior to and/or following tumour feeding, mice were intraperitoneally administered anti-CD25, to inactivate systemic Tregs, or given isotype antibody as a control. Mice which were orally tolerised prior to subcutaneous tumour induction, displayed significantly higher systemic Treg levels (14% vs 6%) and faster tumour growth rates than controls (p<0.05). Complete regression of tumours were only seen after Treg inactivation and occurred in all groups--this was not inhibited by tumour feeding. The cure rates for Treg inactivation were 60% during tolerisation, 75% during tumour growth and 100% during inactivation for both tolerisation and tumour growth. Depletion of Tregs gave rise to an increased number of Teff cells. Treg depletion post-tolerisation and post-tumour induction led to the complete regression of all tumours on tumour bearing mice. Oral administration of tumour tissue, confers a tumour growth advantage and is accompanied by an increase in systemic Treg levels. The administration of anti-CD25 Ab decreased Treg numbers and caused an increase in Teffs. Most notably Treg cell inhibition overcame established oral tolerance with consequent tumor regression, especially relevant to foregut cancers where oral tolerance is likely to be induced by the shedding of tumour tissue into the gut.

Retrospective study and immunohistochemical analysis of canine mammary sarcomas

BACKGROUND

Canine mammary sarcomas (CMSs) are rarely diagnosed in female dogs, which explains the scarcity of immunohistochemical findings concerning those tumors. This paper presents the results of a retrospective study into CMSs and discusses the clinical features of the analyzed tumors, the expression of intermediate filaments CK, Vim, Des and α-SMA, and the expression of p63, Ki67, ERα, PR and p53 protein.

RESULTS

Four percent of all canine mammary tumors (CMTs) were classified as CMSs, and they represented 5.1% of malignant CMTs. The mean age at diagnosis was 11.1 ± 2.8 years. Large breed dogs were more frequently affected (38.7%). The majority of observed CMSs were fibrosarcomas (2.1%). All CMSs expressed vimentin, and higher levels of vimentin expression were noted in fibrosarcomas and osteosarcomas. Ki67 expression was significantly correlated with the grade of CMS.

CONCLUSIONS

Our results revealed that CMSs form a heterogeneous group, therefore, immunohistochemical examinations could support differential and final diagnosis. Although this study analyzed a limited number of samples, the reported results can expand our knowledge about CMSs. Further work is required in this field.

[Fibrosarcomatous dermatofibrosarcoma protuberans: a clinicopathological analysis of 12 cases]

OBJECTIVE

To investigate the clinical pathological features of fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP).

METHODS

The clinical history, histopathological features and immunohistochemical characteristics were analyzed in twelve cases of FS-DFSP from January 1997 to February 2011, and related literature were reviewed.

RESULTS

Age of the patients (2 females, 10 males) at diagnosis ranged from 41 to 70 years (mean 53 years). Among the 12 cases of FS-DFSP, 9 cases aroused in recurrent ordinary DFSP. Histologically, FS areas in FS-DFSP were characterized by a fascicular and highly cellular histology, frequently showing a characteristic herringbone pattern. FS-DFSP showed diminishment of CD34 staining in FS areas. The labeling index of Ki-67 was much higher in the FS areas (10%-40%) than that in the conventional DFSP areas (2%-5%). All the patients were treated by operation with local excision or wide excision. Postoperative radiotherapy and chemotherapy was administered in two cases respectively. Follow-up information in 9 of 12 patients (9 to 86 months) revealed local recurrence in 6 patients. Distant metastases were seen in two patients. One patient was died in the follow up period.

CONCLUSIONS

FS-DFSP is a rare and unique subtype of DFSP and is associated with significant elevated risk of both local and distance metastasis, usually followed by poor outcome. Compared to ordinary DFSP as a borderline neoplasm, FS-DFSP should be considered as a malignant tumor.

In vivo demonstration of cancer molecular imaging with ultrasound radiation force and buried-ligand microbubbles

In designing targeted contrast agent materials for imaging, the need to present a targeting ligand for recognition and binding by the target is counterbalanced by the need to minimize interactions with plasma components and to avoid recognition by the immune system. We have previously reported on a microbubble imaging probe for ultrasound molecular imaging that uses a buried-ligand surface architecture to minimize unwanted interactions and immunogenicity. Here we examine for the first time the utility of this approach for in vivo molecular imaging. In accordance with previous results, we showed a threefold increase in circulation persistence through the tumor of a fibrosarcoma model in comparison with controls. The buried-ligand microbubbles were then activated for targeted adhesion through the application of noninvasive ultrasound radiation forces applied specifically to the tumor region. Using a clinical ultrasound scanner, microbubbles were activated, imaged, and silenced. The results showed visually conspicuous images of tumor neovasculature and a twofold increase in ultrasound radiation force enhancement of acoustic contrast intensity for buried-ligand microbubbles, whereas no such increase was found for exposed-ligand microbubbles. We therefore conclude that the use of acoustically active buried-ligand microbubbles for ultrasound molecular imaging bridges the demand for low immunogenicity with the necessity of maintaining targeting efficacy and imaging conspicuity in vivo.

Malignant progressive tumor cell clone exhibits significant up-regulation of cofilin-2 and 27-kDa modified form of cofilin-1 compared to regressive clone

QR-32 is a regressive murine fibrosarcoma cell clone which cannot grow when they are transplanted in mice; QRsP-11 is a progressive malignant tumor cell clone derived from QR-32 which shows strong tumorigenicity. A recent study showed there to be differentially expressed up-regulated and down-regulated proteins in these cells, which were identified by proteomic differential display analyses by using two-dimensional gel electrophoresis and mass spectrometry. Cofilins are small proteins of less than 20 kDa. Their function is the regulation of actin assembly. Cofilin-1 is a small ubiquitous protein, and regulates actin dynamics by means of binding to actin filaments. Cofilin-1 plays roles in cell migration, proliferation and phagocytosis. Cofilin-2 is also a small protein, but it is mainly expressed in skeletal and cardiac muscles. There are many reports showing the positive correlation between the level of cofilin-1 and cancer progression. We have also reported an increased expression of cofilin-1 in pancreatic cancer tissues compared to adjacent paired normal tissues. On the other hand, cofilin-2 was significantly less expressed in pancreatic cancer tissues. Therefore, the present study investigated the comparison of the levels of cofilin-1 and cofilin-2 in regressive QR-32 and progressive QRsP-11cells by western blotting. Cofilin-2 was significantly up-regulated in QRsP-11 compared to QR-32 cells (p<0.001). On the other hand, the difference of the intensities of the bands of cofilin-1 (18 kDa) in QR-32 and QRsP-11 was not significant. However, bands of 27 kDa showed a quite different intensity between QR-32 and QRsP-11, with much higher intensities in QRsP-11 compared to QR-32 (p<0.001). These results suggested that the 27-kDa protein recognized by the antibody against cofilin-1 is a possible biomarker for progressive tumor cells.

MT1-MMP prevents growth inhibition by three dimensional fibronectin matrix

The extracellular microenvironment plays a key role in regulation of cellular functions and growth control. We show here that membrane-type 1 matrix metalloproteinase (MT1-MMP) acts as a growth promoter in confluent culture. When MT1-MMP was silenced in HT1080 fibrosarcoma cells, cells created three dimensional (3D) fibronectin matrix in a confluent culture, and growth of cells embedded within it was retarded. Formation of 3D fibronectin matrix initiated by MT1-MMP silencing was impeded by knockdown of either FN or integrin β₁, which resulted in restoration of cell growth. When cells in 3D fibronectin matrix were treated with integrin β₁ inhibitory antibody, cells underwent S phase entry. These results suggest that MT1-MMP prevents growth suppression by 3D fibronectin matrix, which is mediated through integrin β₁.

Cerenkov luminescence tomography of aminopeptidase N (APN/CD13) expression in mice bearing HT1080 tumors

In vivo imaging of aminopeptidase N (APN/CD13) expression is crucial for the early detection of cancer. This study attempted to show that APN/CD13 expression can be imaged and quantified with novel Cerenkov luminescence tomography (CLT). Na131I with various activities was placed at different depths in a tissue-mimicking phantom, and various porcine tissues and luminescent images were acquired. The binding of 131I-NGR with human fibrosarcoma HT1080 and human colon cancer HT-29 cells was detected with Cerenkov luminescence imaging (CLI). Nude mice bearing HT-1080 tumors were imaged after injection with 131I-NGR using both planar and tomographic CLI methods. The penetration depth increased with ascending activity of Na131I. There was a robust linear correlation between the optical signal intensity and the HT1080 cell numbers (r2 = .9691), as well as the activity (r2 = .9860). The three-dimensional visualization CLT results clearly showed that 131I-NGR uptake in tumor tissues represented a high expression of the APN/CD13 receptor. CLT also allowed quantifying 131I-NGR uptake in tumor tissues showing an average activity of 0.1388 ± 4.6788E-6 MBq in tumor tissues. Our study indicated that 131I-NGR combined with CLT allowed us to image and quantify tumor-associated APN/CD13 expression noninvasively. The promising CLT technique could be potentially used for sensitively evaluating tumor angiogenesis in vivo.

Low molecular weight heparin suppresses receptor for advanced glycation end products-mediated expression of malignant phenotype in human fibrosarcoma cells

The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor and its engagement by ligands such as high mobility group box 1 (HMGB1) is implicated in tumor growth and metastasis. Low molecular weight heparin (LMWH) has an antagonistic effect on the RAGE axis and is also reported to exert an antitumor effect beyond the known activity of anticoagulation. However, the link between the anti-RAGE and antitumor activities of LMWH has not yet to be fully elucidated. In this study, we investigated whether LMWH could inhibit tumor cell proliferation, invasion, and metastasis by blocking the RAGE axis using in vitro and in vivo assay systems. Stably transformed HT1080 human fibrosarcoma cell lines were obtained, including human full-length RAGE-overexpressing (HT1080(RAGE)), RAGE dominant-negative, intracellular tail-deleted RAGE-overexpressing (HT1080(dnRAGE)), and mock-transfected control (HT1080(mock)) cells. Confocal microscopy showed the expression of HMGB1 and RAGE in HT1080 cells. The LMWH significantly inhibited HMGB1-induced NFκB activation through RAGE using an NFκB-dependent luciferase reporter assay and the HT1080 cell lines. Overexpression of RAGE significantly accelerated, but dnRAGE expression attenuated HT1080 cell proliferation and invasion in vitro, along with similar effects on local tumor mass growth and lung metastasis in vivo. Treatment with LMWH significantly inhibited the migration, invasion, tumor formation, and lung metastasis of HT1080(RAGE) cells, but not of HT1080(mock) or HT1080(dnRAGE) cells. In conclusion, this study revealed that RAGE exacerbated the malignant phenotype of human fibrosarcoma cells, and that this exacerbation could be ameliorated by LMWH. It is suggested that LMWH has therapeutic potential in patients with certain types of malignant tumors.

Role of macrophage targeting in the antitumor activity of trabectedin

There is widespread interest in macrophages as a therapeutic target in cancer. Here, we demonstrate that trabectedin, a recently approved chemotherapeutic agent, induces rapid apoptosis exclusively in mononuclear phagocytes. In four mouse tumor models, trabectedin caused selective depletion of monocytes/macrophages in blood, spleens, and tumors, with an associated reduction of angiogenesis. By using trabectedin-resistant tumor cells and myeloid cell transfer or depletion experiments, we demonstrate that cytotoxicity on mononuclear phagocytes is a key component of its antitumor activity. Monocyte depletion, including tumor-associated macrophages, was observed in treated tumor patients. Trabectedin activates caspase-8-dependent apoptosis; selectivity for monocytes versus neutrophils and lymphocytes is due to differential expression of signaling and decoy TRAIL receptors. This unexpected property may be exploited in different therapeutic strategies.

Proteomic analysis showed down-regulation of nucleophosmin in progressive tumor cells compared to regressive tumor cells

Important strategies against cancer are based on the understanding of the mechanisms of tumor progression. To elucidate alterations regarding tumor progression, we have performed proteomic differential display analysis for the expression of intracellular proteins in the regressive murine fibrosarcoma cell clone QR-32 and the progressive malignant tumor cell clone QRsP-11, derived from QR-32, by means of combination of two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and we have previously reported on relevant results. However, besides the protein spots which we already reported, we identified three more particular spots of interest. In the present study, two-dimensional western blot analysis demonstrated a significantly lower expression of three isoforms of nucleophosmin in progressive, compared to regressive cell clones. These results suggest that the down-regulation of the identified nucleophosmin proteins in QRsP-11 cells compared to QR-32 cells is possibly related to tumor malignant progression.

[Inhibition of tumor cell invasion and induction of apoptosis by ubenimex]

This study is to investigate the effects of ubenimex on tumor cell invasion and apoptosis, dose relationship and mechanism. Immunofluorescence staining was performed to detect the expression of CD13 in HT-1080 cells. MTT assay was used to analyze the effect of ubenimex on cell proliferation. Annexin V-EGFP/PI was used to detect apoptotic cells by flow cytometry. Cell cycle was analyzed using flow cytometry. Ala-pNA was used as substrate to evaluate the effect of ubenimex on the aminopeptidase activity. Transwell assay was used to analyze the effect of ubenimex on cell invasion and migration ability. Western blotting was used to detect the expression level of CD13. MMP activity was analyzed using gelatin zymography. The results showed that ubenimex at high concentration inhibited the proliferation of HT-1080 cells (IC50: 3.8 mg x mL(-1)), and induced cell apoptosis. Cell cycle was blocked at G1 phase. Ubenimex at low concentration inhibited the aminopeptidase activity of HT-1080 cells (IC50: 8.3 microg x mL(-1)) and inhibited cell invasion, but it had no effects on the cell migration and proliferation. Ubenimex had no effects on CD13 expression and MMP activity. In conclusion, ubenimex at low concentration can inhibit the invasion ability of tumor cells by directly inhibiting the aminopeptidase activity; ubenimex at high concentration can inhibit the proliferation of tumor cells and induce cell apoptosis by a CD13-independent pathway.

Vasculogenic mimicry of HT1080 tumour cells in vivo: critical role of HIF-1α-neuropilin-1 axis

HT1080 - a human fibrosarcoma-derived cell line – forms aggressive angiogenic tumours in immuno-compromised mice. In spite of its extensive use as a model of tumour angiogenesis, the molecular event(s) initiating the angiogenic program in these cells are not known. Since hypoxia stimulates tumour angiogenesis, we examined the hypoxia-induced events evoked in these cells. In contrast to cells grown under normoxic conditions, hypoxia-primed (1% O₂) HT1080 cells formed robust tubules on growth factor-reduced matrigel and formed significantly larger tumours in xenograft models in a chetomin-sensitive manner, indicating the role of HIF-1α-mediated transcription in these processes. Immuno-histochemical analyses of tumours formed by GFP-expressing HT1080 cells clearly showed that the tumour cells themselves expressed various angiogenic markers including Neuropilin-1 (NRP-1) and formed functional vessels containing red blood cells, thereby unambiguously demonstrating the vasculogenic mimicry of HT1080 cells in vivo. Experiments performed with the HT1080 cells stably transfected with plasmid constructs expressing shNRP-1 or full-length NRP-1 clearly established that the HIF1α-mediated up-regulation of NRP-1 played a deterministic role in the process. Hypoxia-exposure resulted in an up-regulation of c-Myc and OCT3/4 and a down-regulation of KLF4 mRNAs, suggesting their involvement in the tumour formation and angiogenesis. However, silencing of NRP-1 alone, though not affecting proliferation in culture, was sufficient to abrogate the tumour formation completely; clearly establishing that the hypoxia-mediated HIF-1α-dependent up-regulation of NRP-1 is a critical molecular event involved in the vasculogenic mimicry and tumor formation by HT1080 cells in vivo.

Evolutionarily repurposed networks reveal the well-known antifungal drug thiabendazole to be a novel vascular disrupting agent

Analysis of a genetic module repurposed between yeast and vertebrates reveals that a common antifungal medication is also a potent vascular disrupting agent.

Studies in diverse organisms have revealed a surprising depth to the evolutionary conservation of genetic modules. For example, a systematic analysis of such conserved modules has recently shown that genes in yeast that maintain cell walls have been repurposed in vertebrates to regulate vein and artery growth. We reasoned that by analyzing this particular module, we might identify small molecules targeting the yeast pathway that also act as angiogenesis inhibitors suitable for chemotherapy. This insight led to the finding that thiabendazole, an orally available antifungal drug in clinical use for 40 years, also potently inhibits angiogenesis in animal models and in human cells. Moreover, in vivo time-lapse imaging revealed that thiabendazole reversibly disassembles newly established blood vessels, marking it as vascular disrupting agent (VDA) and thus as a potential complementary therapeutic for use in combination with current anti-angiogenic therapies. Importantly, we also show that thiabendazole slows tumor growth and decreases vascular density in preclinical fibrosarcoma xenografts. Thus, an exploration of the evolutionary repurposing of gene networks has led directly to the identification of a potential new therapeutic application for an inexpensive drug that is already approved for clinical use in humans.

Yeast cells and vertebrate blood vessels would not seem to have much in common. However, we have discovered that during the course of evolution, a group of proteins whose function in yeast is to maintain cell walls has found an alternative use in vertebrates regulating angiogenesis. This remarkable repurposing of the proteins during evolution led us to hypothesize that, despite the different functions of the proteins in humans compared to yeast, drugs that modulated the yeast pathway might also modulate angiogenesis in humans and in animal models. One compound seemed a particularly promising candidate for this sort of approach: thiabendazole (TBZ), which has been in clinical use as a systemic antifungal and deworming treatment for 40 years. Gratifyingly, our study shows that TBZ is indeed able to act as a vascular disrupting agent and an angiogenesis inhibitor. Notably, TBZ also slowed tumor growth and decreased vascular density in human tumors grafted into mice. TBZ’s historical safety data and low cost make it an outstanding candidate for translation to clinical use as a complement to current anti-angiogenic strategies for the treatment of cancer. Our work demonstrates how model organisms from distant branches of the evolutionary tree can be exploited to arrive at a promising new drug.

Derivation of feline vaccine-associated fibrosarcoma cell line and its growth on chick embryo chorioallantoic membrane - a new in vivo model for veterinary oncological studies

Feline vaccine associated fibrosarcomas are the second most common skin tumor in cats. Methods of treatment are: surgery, chemotherapy and radiotherapy. Nevertheless, the usage of cytostatics in feline vaccine associated sarcoma therapy is limited due to their adverse side effects, high toxicity and low biodistribution after i.v. injection. Therefore, much research on new therapeutic drugs is being conducted. In human medicine, the chick embryo chorioallantoic membrane (CAM) model is used as a cheap and easy to perform assay to assess new drug effectiveness in cancer treatment. Various human cell lines have different tumors growth on CAM. In veterinary medicine such model has not been described yet. In the present article derivation of feline vaccine associated fibrosarcoma cell line and its growth on CAM is described. The cell line and the tumor grown were confirmed by histopathological and immunohistochemical examination. As far as we believe, this is the first attempt to create such model, which may be used for further in vivo studies in veterinary oncology.

Low-grade myofibroblastic sarcoma of the maxillary region in a dog

A subcutaneous tumour was identified in the maxillary region of a 14-year-old mixed breed dog. This tumour had grown rapidly over 2 weeks. Microscopically, the tumour had ill-defined borders and was composed of bundles and whorls of atypical spindle cells accompanied by abundant collagen fibres. Immunohistochemically, neoplastic cells were immunoreactive for vimentin, α-smooth muscle actin and calponin and negative for S100 protein, von Willebrand factor, desmin and smoothelin. These results suggested that the neoplastic cells were derived from myofibroblasts and that the tumour was a low-grade myofibroblastic sarcoma.

Superoxide plays critical roles in electrotaxis of fibrosarcoma cells via activation of ERK and reorganization of the cytoskeleton

Direct-current electrical field (DCEF) induces directional migration in many cell types by activating intracellular signaling pathways. However, the mechanisms coupling the extracellular electric stimulation to the intracellular signals remain largely unknown. In this study, we show that DCEF directs migration of HT-1080 fibrosarcoma cells to the cathode, stimulates generation of hydrogen peroxide and superoxide through the activation of NADPH oxidase, induces anode-facing cytoskeleton polarization, and activates ERK signaling. Subsequent studies demonstrate that the electrotaxis of HT-1080 fibrosarcoma cells is abolished by NADPH oxidase inhibitor and overexpression of manganese superoxide dismutase (MnSOD), an enzyme that hydrolyzes superoxide. In contrast, overexpression of catalases, which hydrolyze hydrogen peroxide, does not affect electrotaxis. MnSOD overexpression also eliminates cytoskeleton polarization as well as the activation of AKT, ERKs, and p38. In contrast, under catalase overexpression, the cytoskeleton still polarizes and p38 activation is affected. Finally, we show that inhibition of ERK activation also abolishes DCEF-induced directional migration and cytoskeleton polarization. Collectively, our results indicate that superoxide plays critical roles in DCEF-induced directional migration of fibrosarcoma cells, possibly by regulating the activation of ERKs. This study provides novel insights into the current understanding of DCEF-mediated cancer cell directional migration and metastasis.

Distinct cytoplasmic and nuclear functions of the stress induced protein DDIT3/CHOP/GADD153

DDIT3, also known as GADD153 or CHOP, encodes a basic leucine zipper transcription factor of the dimer forming C/EBP family. DDIT3 is known as a key regulator of cellular stress response, but its target genes and functions are not well characterized. Here, we applied a genome wide microarray based expression analysis to identify DDIT3 target genes and functions. By analyzing cells carrying tamoxifen inducible DDIT3 expression constructs we show distinct gene expression profiles for cells with cytoplasmic and nuclear localized DDIT3. Of 175 target genes identified only 3 were regulated by DDIT3 in both cellular localizations. More than two thirds of the genes were downregulated, supporting a role for DDIT3 as a dominant negative factor that could act by either cytoplasmic or nuclear sequestration of dimer forming transcription factor partners. Functional annotation of target genes showed cell migration, proliferation and apoptosis/survival as the most affected categories. Cytoplasmic DDIT3 affected more migration associated genes, while nuclear DDIT3 regulated more cell cycle controlling genes. Cell culture experiments confirmed that cytoplasmic DDIT3 inhibited migration, while nuclear DDIT3 caused a G1 cell cycle arrest. Promoters of target genes showed no common sequence motifs, reflecting that DDIT3 forms heterodimers with several alternative transcription factors that bind to different motifs. We conclude that expression of cytoplasmic DDIT3 regulated 94 genes. Nuclear translocation of DDIT3 regulated 81 additional genes linked to functions already affected by cytoplasmic DDIT3. Characterization of DDIT3 regulated functions helps understanding its role in stress response and involvement in cancer and degenerative disorders.