CD105 expression in cancer-associated fibroblasts: a biomarker for bone metastasis in early invasive ductal breast cancer patients

Introduction: Bone metastasis is one of the causes that mainly decrease survival in patients with advanced breast cancer. Therefore, it is essential to find prognostic markers for the occurrence of this type of metastasis during the early stage of the disease. Currently, cancer-associated fibroblasts, which represent 80% of the fibroblasts present in the tumor microenvironment, are an interesting target for studying new biomarkers and developing alternative therapies. This study evaluated the prognostic significance of the CD105 expression in cancer-associated fibroblasts in early breast cancer patients. Methods: Immunohistochemistry was used to assess CD105 expression in invasive ductal breast carcinomas (n = 342), analyzing its association with clinical and pathological characteristics. Results: High CD105 expression in cancer-associated fibroblasts was associated with an increased risk of metastatic occurrence (p = 0.0003), particularly bone metastasis (p = 0.0005). Furthermore, high CD105 expression was associated with shorter metastasis-free survival, bone metastasis-free survival, and overall survival (p = 0.0002, 0.0006, and 0.0002, respectively). CD105 expression also constituted an independent prognostic factor for metastasis-free survival, bone metastasis-free survival, and overall survival (p = 0.0003, 0.0006, and 0.0001, respectively). Discussion: The high CD105 expression in cancer-associated fibroblasts is an independent prognostic marker for bone metastasis in early breast cancer patients. Therefore, the evaluation of CD105(+) CAFs could be crucial to stratify BCPs based on their individual risk profile for the development of BM, enhancing treatment strategies and outcomes.

Effects of pharmacological inhibition of hyaluronic acid synthesis on experimental endometriosis

BACKGROUND

Dysregulated hyaluronic acid (HA) metabolism has been shown to be implicated in several pathologies including endometriosis. 4-Methylumbelliferone (4MU) is an HA synthesis inhibitor with proven antitumour activity. In this study, we aim to evaluate the effect of 4MU on endometriosis development both in vivo and in vitro.

METHODS

Endometriosis was surgically induced by uterine tissue auto-transplantation in 32 two-month-old BALB/c mice. Animals were designated into the early or late starting treatment group, which initiated on day 2 or day 15 after surgery, respectively. Within each group, 4MU 200 mg/kg/day or vehicle (Control) were administered by oesophageal gavage for 28 days. After sacrifice, the percentage of developed lesions, lesion size, cell proliferation, vascularization and HA deposition within the endometriotic-like lesions were evaluated. Cell viability was assessed in endometrial epithelial cells (ECC-1) and in endometrial stromal cells (t-HESC); and migration was evaluated in t-HESC.

RESULTS

There was a significant reduction in the percentage of developed lesions in mice that started the 4MU treatment on day 2 compared with its respective control group, and compared with those that started treatment on day 15. However, no significant changes were found when analysing endometriotic-like lesion's cell proliferation, vascularization and HA deposition. In vitro, both cell viability and migration were inhibited by 4MU treatment.

CONCLUSIONS

The inhibition of HA synthesis could be a beneficial and alternative option to treat endometriosis at the early stage of the disease. Further research is necessary to elucidate 4MU's mechanism of action and better strategies for delivering this promising drug.

Proteoglycans: A Tool for Detecting Hyaluronan by ELISA-Like Methods

Hyaluronan is a non-sulfated glycosaminoglycan synthesized on the plasma membrane of almost all mammalian cells, which can interact with different proteoglycans of the extracellular matrix. Aggrecan, versican, neurocan, and brevican are proteoglycans whose structures present a specific protein domain called "link module," which allows hyaluronan binding. Therefore, they can be helpful for assays that detect hyaluronan. For example, ELISA-like methods developed to measure hyaluronan amounts in solution are based on specific interactions between this molecule and the link module present in aggrecan or other hyaluronan-binding proteins (hyaladherins).

β-Catenin is reduced in membranes of human prolactinoma cells and it is inhibited by temozolomide in prolactin secreting tumor models

INTRODUCTION: Prolactinomas are the most frequent pituitary tumor subtype. Despite most of them respond to medical treatment, a proportion are resistant and become a challenge in clinical management. Wnt/β-Catenin pathway has been implicated in several cancers including pituitary tumors and other sellar region malignancies. Interestingly, Wnt/β-Catenin inhibition augments the cytotoxicity of the chemotherapeutic agent Temozolomide (TMZ) in different cancers. TMZ is now being implemented as rescue therapy for aggressive pituitary adenoma treatment. However, the molecular mechanisms associated with TMZ action in pituitary tumors remain unclear. OBJECTIVES: Our aims in the present study were to evaluate differential β-Catenin expression in human resistant prolactinomas and Wnt/β-Catenin signaling activation and involvement in Prolactin (PRL) secreting experimental models treated with TMZ. RESULTS: We first evaluated by immunohistochemistry β-Catenin localization in human resistant prolactinomas in which we demonstrated reduced membrane β-Catenin in prolactinoma cells compared to normal pituitaries, independently of the Ki-67 proliferation indexes. In turn, in vivo 15 mg/kg of orally administered TMZ markedly reduced PRL production and increased prolactinoma cell apoptosis in mice bearing xenografted prolactinomas. Intratumoral β-Catenin strongly correlated with Prl and Cyclin D1, and importantly, TMZ downregulated both β-Catenin and Cyclin D1, supporting their significance in prolactinoma growth and as candidates of therapeutic targets. When tested in vitro, TMZ directly reduced MMQ cell viability, increased apoptosis and produced G2/M cell cycle arrest. Remarkably, β-Catenin activation and VEGF secretion were inhibited by TMZ in vitro. CONCLUSIONS: We concluded that dopamine resistant prolactinomas undergo a β-Catenin relocalization in relation to normal pituitaries and that TMZ restrains experimental prolactinoma tumorigenicity by reducing PRL production and β-Catenin activation. Together, our findings contribute to the understanding of Wnt/β-Catenin implication in prolactinoma maintenance and TMZ therapy, opening the opportunity of new treatment strategies for aggressive and resistant pituitary tumors.

The effects of sulfated hyaluronan in breast, lung and colorectal carcinoma and monocytes/macrophages cells: Its role in angiogenesis and tumor progression

Hyaluronan (HA) is a component of the extracellular matrix (ECM) it is the main non-sulfated glycosaminoglycan able to modulate cell behavior in the healthy and tumor context. Sulfated hyaluronan (sHA) is a biomaterial derived from chemical modifications of HA, since this molecule is not naturally sulfated. The HA sulfation modifies several properties of the native molecule, acquiring antitumor properties in different cancers. In this study, we evaluated the action of sHA of ~30-60 kDa with different degrees of sulfation (0.7 sHA1 and 2.5 sHA3) on tumor cells of a breast, lung, and colorectal cancer model and its action on other cells of the tumor microenvironment, such as endothelial and monocytes/macrophage cells. Our data showed that in breast and lung tumor cells, sHA3 is able to modulate cell viability, cytotoxicity, and proliferation, but no effects were observed on colorectal cancer cells. In 3D cultures of breast and lung cancer cells, sHA3 diminished the size of the tumorsphere and modulated total HA levels. In these tumor models, treatment of monocytes/macrophages with sHA3 showed a downregulation of the expression of angiogenic factors. We also observed a decrease in endothelial cell migration and modulation of the hyaluronan-binding protein TSG-6. In the breast in vivo xenograft model, monocytes/macrophages preincubated with sHA1 or sHA3 decreased tumor vasculature, TSG-6 and HA levels. Besides, in silico analysis showed an association of TSG-6, HAS2, and IL-8 with biological processes implicated in the progression of the tumor. Taken together, our data indicate that sHA in a breast and lung tumor context is able to induce an antiangiogenic action on tumor cells as well as in monocytes/macrophages (Mo/MØ) by modulation of endothelial migration, angiogenic factors, and vessel formation.

Antiproliferative and antiangiogenic effects of ammonium tetrathiomolybdate in a model of endometriosis

AIMS

Copper (Cu) is involved in the endometriosis progression. Herein, an experimental endometriosis model was used to evaluate whether its chelation with ammonium tetrathiomolybdate (TM) affects the proliferation and angiogenesis in endometriotic-like lesions and the participation of oxidative stress in these processes.

MAIN METHODS

Female C57BL/6 mice were divided into three groups: sham-operated mice, endometriosis-induced mice, and TM-treated endometriosis-induced mice. Each animal in the third group received 0.3 mg of TM/day in their drinking water from the postoperative 15th day. The samples were collected after one month of induced pathology. In peritoneal fluids, Cu and estradiol levels were determined by electrothermal atomic absorption spectrometry and electrochemiluminescence, respectively. Endometriotic-like lesions were processed for the analysis of cell proliferation by PCNA immunohistochemistry, the expression of angiogenic markers by RT-qPCR, the presence of endothelial cells by immunofluorescent staining, and oxidative stress applying spectrophotometric methods.

KEY FINDINGS

TM treatment decreased Cu and estradiol levels, which were increased by this pathology. In lesions, TM induced: (a) a decrease in tissue weight and volume, (b) a decrease in PCNA-positive cells, (c) antiangiogenic effects by decreasing the number of blood vessels, the mRNA expression of fibroblast growth factor 2 (Fgf2) and platelet-derived growth factor subunit B (Pdgfb), and the presence of endothelial cells, (d) a decrease in antioxidant activity and an increase in lipid peroxidation.

SIGNIFICANCE

TM is a highly effective antiproliferative and antiangiogenic agent, modulating oxidative imbalance in endometriosis. Its anti-endometriotic potential is an attractive feature of TM as a possible non-hormonal treatment.

Up-regulation of pro-angiogenic molecules and events does not relate with an angiogenic switch in metastatic osteosarcoma cells but to cell survival features

Osteosarcoma (OS) is the most frequent malignant bone tumor, affecting predominantly children. Metastases represent a major clinical challenge and an estimated 80% would present undetectable micrometastases at diagnosis. The identification of metastatic traits and molecules would impact in micrometastasis management. We demonstrated that OS LM7 metastatic cells secretome was able to induce microvascular endothelium cell rearrangements, an angiogenic-related trait. A proteomic analysis indicated a gain in angiogenic-related pathways in these cells, as compared to their parental-non-metastatic OS SAOS2 cells counterpart. Further, factors with proangiogenic functions like VEGF and PDGF were upregulated in LM7 cells. However, no differential angiogenic response was induced by LM7 cells in vivo. Regulation of the Fas-FasL axis is key for OS cells to colonize the lungs in this model. Analysis of the proteomic data with emphasis in apoptosis pathways and related processes revealed that the percentage of genes associated with those, presented similar levels in SAOS2 and LM7 cells. Further, the balance of expression levels of proteins with pro- and antiapoptotic functions in both cell types was subtle. Interestingly and of relevance to the model, Fas associated Factor 1 (FAF1), which participates in Fas signaling, was present in LM7 cells and was not detected in SAOS2 cells. The subtle differences in apoptosis-related events and molecules, together with the reported cell-survival functions of the identified angiogenic factors and the increased survival features that we observed in LM7 cells, suggest that the gain in angiogenesis-related pathways in metastatic OS cells would relate to a prosurvival switch rather to an angiogenic switch as an advantage feature to colonize the lungs. OS metastatic cells also displayed higher adhesion towards microvascular endothelium cells suggesting an advantage for tissue colonization. A gain in angiogenesis pathways and molecules does not result in major angiogenic potential. Together, our results suggest that metastatic OS cells would elicit signaling associated to a prosurvival phenotype, allowing homing into the hostile site for metastasis. During the gain of metastatic traits process, cell populations displaying higher adhesive ability to microvascular endothelium, negative regulation of the Fas-FasL axis in the lung parenchyma and a prosurvival switch, would be selected. This opens a new scenario where antiangiogenic treatments would affect cell survival rather than angiogenesis, and provides a molecular panel of expression that may help in distinguishing OS cells with different metastatic potential.

Initial Identification of UDP-Glucose Dehydrogenase as a Prognostic Marker in Breast Cancer Patients, Which Facilitates Epirubicin Resistance and Regulates Hyaluronan Synthesis in MDA-MB-231 Cells

UDP-glucose-dehydrogenase (UGDH) synthesizes UDP-glucuronic acid. It is involved in epirubicin detoxification and hyaluronan synthesis. This work aimed to evaluate the effect of UGDH knockdown on epirubicin response and hyaluronan metabolism in MDA-MB-231 breast cancer cells. Additionally, the aim was to determine UGDH as a possible prognosis marker in breast cancer. We studied UGDH expression in tumors and adjacent tissue from breast cancer patients. The prognostic value of UGDH was studied using a public Kaplan–Meier plotter. MDA-MB-231 cells were knocked-down for UGDH and treated with epirubicin. Epirubicin-accumulation and apoptosis were analyzed by flow cytometry. Hyaluronan-coated matrix and metabolism were determined. Autophagic-LC3-II was studied by Western blot and confocal microscopy. Epirubicin accumulation increased and apoptosis decreased during UGDH knockdown. Hyaluronan-coated matrix increased and a positive modulation of autophagy was detected. Higher levels of UGDH were correlated with worse prognosis in triple-negative breast cancer patients that received chemotherapy. High expression of UGDH was found in tumoral tissue from HER2^--patients. However, UGDH knockdown contributes to epirubicin resistance, which might be associated with increases in the expression, deposition and catabolism of hyaluronan. The results obtained allowed us to propose UGDH as a new prognostic marker in breast cancer, positively associated with development of epirubicin resistance and modulation of extracellular matrix.

Chemoimmunotherapy for advanced gastrointestinal carcinomas: A successful combination of gene therapy and cyclophosphamide

The combination of a single low dose of cyclophosphamide (Cy) with the adenovirus-mediated gene transfer of interleukin-12 (AdIL-12) might represent a successful therapy for experimental gastrointestinal tumors. This approach has been proven to revert immunosuppressive mechanisms elicited by cancer cells and to synergistically promote antitumor immunity. In addition, this therapeutic regimen has been shown to be more efficient in achieving complete tumor regressions in mice than the application of a metronomic schedule of Cy plus AdIL-12.

Hyaluronan Metabolism is Associated with DNA Repair Genes in Breast and Colorectal Cancer. Screening of Potential Progression Markers Using qPCR

In this work, we compared mRNA levels of Hyaluronan (HA) metabolism members and BRCA genes, known to be involved in the tumoral process, between tumor and non-tumor adjacent tissue and its correlation with previously proposed biomarkers (ER, PR, HER2 and KI67) in order to assess their value as a progression biomarkers. We show alteration in HA metabolism in colorectal but not breast cancer. However, we found a decrease in Hyaluronidase 1 HYAL1 levels in the breast but not colorectal cancer. We also show lower HA levels in tumor compared with normal tissue that could indicate a possible influence of tumor on its surrounding "normal" tissue. In both breast and colorectal cancer, CD44 and BRCA2 showed a strong positive correlation. Besides, our results show first indicators that qPCR of the analyzed genes could be used as an easy and low cost procedure for the evaluation of molecular markers we propose here.

Contribution of neural crest and GLAST+ Wnt1+ bone marrow pericytes with liver fibrogenesis and/or regeneration

BACKGROUND AND AIMS

Liver fibrosis results from cycles of liver damage and scar formation. We herein aimed at analysing neural crest cells and/or bone marrow stromal cells contribution to the liver.

METHODS

Two liver fibrosis and one hepatectomy model were applied on double-transgenic loxP-Cre mouse lines.

RESULTS

Increased numbers of glia with more complex processes were found in fibrotic livers. During embryonic development, only few cells were traced in the liver and bone marrow, in a minor fraction of mice of different neural crest reporter strains analysed: therefore, a neural crest origin of such cells is doubtful. In the fibrotic liver, a significantly higher incidence of endothelial cells and hepatocyte-like cells expressing the reporter gene Tomato were found in Wnt1-Cre-Tom and GLAST-CreERT2-Tom mice. Consistently, during early fibrogenesis stromal Wnt1-traced cells, with progenitor (CFU-F) properties, get likely mobilized to peripheral blood. Circulating adult Wnt1-traced cells are stromal cells and lack from the expression of other bone marrow and endothelial progenitor cells markers. Furthermore, in a 70% hepatectomy model GLAST⁺ Wnt1-traced pericytes were found to be mobilized from the bone marrow and the incidence of GLAST-traced hepatocyte-like cells was increased. Finally, GLAST-traced hepatocyte like-cells were found to maintain the expression of stromal markers.

CONCLUSIONS

Our data suggest a gliosis process during liver fibrogenesis. While neural crest cells probably do not contribute with other liver cell types than glia, GLAST⁺ Wnt1-traced bone marrow pericytes are likely a source of endothelial and hepatocyte-like cells after liver injury and do not contribute to scarring.

Sirtuin 1 reduces hyaluronan synthase 2 expression by inhibiting nuclear translocation of NF-κB and expression of the long-noncoding RNA HAS2-AS1

Hyaluronan (HA) is one of the most prevalent glycosaminoglycans of the vascular extracellular matrix (ECM). Abnormal HA accumulation within blood vessel walls is associated with tissue inflammation and is prominent in most vascular pathological conditions such as atherosclerosis and restenosis. Hyaluronan synthase 2 (HAS2) is the main hyaluronan synthase enzyme involved in HA synthesis and uses cytosolic UDP-glucuronic acid and UDP-GlcNAc as substrates. The synthesis of UDP-glucuronic acid can alter the NAD⁺/NADH ratio via the enzyme UDP-glucose dehydrogenase, which oxidizes the alcohol group at C6 to the COO^- group. Here, we show that HAS2 expression can be modulated by sirtuin 1 (SIRT1), the master metabolic sensor of the cell, belonging to the class of NAD⁺-dependent deacetylases. Our results revealed the following. 1) Treatments of human aortic smooth muscle cells (AoSMCs) with SIRT1 activators (SRT1720 and resveratrol) inhibit both HAS2 expression and accumulation of pericellular HA coats. 2) Tumor necrosis factor α (TNFα) induced HA-mediated monocyte adhesion and AoSMC migration, whereas SIRT1 activation prevented immune cell recruitment and cell motility by reducing the expression levels of the receptor for HA-mediated motility, RHAMM, and the HA-binding protein TNF-stimulated gene 6 protein (TSG6). 3) SIRT1 activation prevented nuclear translocation of NF-κB (p65), which, in turn, reduced the levels of HAS2-AS1, a long-noncoding RNA that epigenetically controls HAS2 mRNA expression. In conclusion, we demonstrate that both HAS2 expression and HA accumulation by AoSMCs are down-regulated by the metabolic sensor SIRT1.

Proteoglycans and glycosaminoglycans as regulators of cancer stem cell function and therapeutic resistance

In contrast to the bulk of the tumor, a subset of cancer cells called cancer stem cells (CSC; or tumor-initiating cells) is characterized by self-renewal, unlimited proliferative potential, expression of multidrug resistance proteins, active DNA repair capacity, apoptosis resistance, and a considerable developmental plasticity. Due to these properties, CSCs display increased resistance to chemo- and radiotherapy. Recent findings indicate that aberrant functions of proteoglycans (PGs) and glycosaminoglycans (GAGs) contribute substantially to the CSC phenotype and therapeutic resistance. In this review, we summarize how the diverse functions of the glycoproteins and carbohydrates facilitate acquisition and maintenance of the CSC phenotype, and how this knowledge can be exploited to develop novel anticancer therapies. For example, the large transmembrane chondroitin sulfate PG NG2/CSPG4 marks stem cell (SC) populations in brain tumors. Cell surface heparan sulfate PGs of the syndecan and glypican families modulate the stemness-associated Wnt, hedgehog, and notch signaling pathways, whereas the interplay of hyaluronan in the SC niche with CSC CD44 determines the maintenance of stemness and promotes therapeutic resistance. A better understanding of the molecular mechanisms by which PGs and GAGs regulate CSC function will aid the development of targeted therapeutic approaches which could avoid relapse after an otherwise successful conventional therapy. Chimeric antigen receptor T cells, PG-primed dendritic cells, PG-targeted antibody-drug conjugates, and inhibitory peptides and glycans have already shown highly promising results in preclinical models.

Hyaluronan preconditioning of monocytes/macrophages affects their angiogenic behavior and regulation of TSG-6 expression in a tumor type-specific manner

Hyaluronan is a glycosaminoglycan normally present in the extracellular matrix in most tissues. Hyaluronan is a crucial player in many processes associated with cancer, such as angiogenesis, invasion, and metastasis. However, little has been reported regarding the action of hyaluronan on monocytes/macrophages (Mo/MØ) in tumor angiogenesis and its consequences on tumor development. In the present study, we investigated the effects of hyaluronan of different sizes on human Mo/MØ angiogenic behavior in colorectal and breast carcinoma. In vitro, the treatment of Mo/MØ with lysates and conditioned media from a breast but not from colorectal carcinoma cell line plus high-molecular weight hyaluronan induced: (a) an increased expression of angiogenic factors VEGF, IL-8, FGF-2, and MMP-2, (b) an increased endothelial cell migration, and (c) a differential expression of hyaluronan-binding protein TSG-6. Similar results were observed in Mo/MØ derived from breast cancer patients treated with tumor lysates. Besides, macrophages primed with high-molecular weight hyaluronan and inoculated in human breast cancer xenograft tumor increased blood vessel formation and diminished TSG-6 levels. In contrast, the effects triggered by high-molecular weight hyaluronan on Mo/MØ in breast cancer context were not observed in the context of colorectal carcinoma. Taken together, these results indicate that the effect of high-molecular weight hyaluronan as an inductor of the angiogenic behavior of macrophages in breast tumor context is in part consequence of the presence of TSG-6.

Co-treatment of tumor cells with hyaluronan plus doxorubicin affects endothelial cell behavior independently of VEGF expression

Hyaluronan, the main glycosaminoglycan of extracellular matrices, is concentrated in tissues with high cell proliferation and migration rates. In cancer, hyaluronan expression is altered and it becomes fragmented into low-molecular-weight forms, affecting mechanisms associated with cell proliferation, invasion, angiogenesis and multidrug resistance. Here, we analyzed the effect of low-molecular-weight hyaluronan on the response of T lymphoma, osteosarcoma, and mammary adenocarcinoma cell lines to the antineoplastic drug doxorubicin, and whether co-treatment with hyaluronan and doxorubicin modified the behavior of endothelial cells. Our aim was to associate the hyaluronan-doxorubicin response with angiogenic alterations in these tumors. After hyaluronan and doxorubicin co-treatment, hyaluronan altered drug accumulation and modulated the expression of ATP-binding cassette transporters in T-cell lymphoma cells. In contrast, no changes in drug accumulation were observed in cells from solid tumors, indicating that hyaluronan might not affect drug efflux. However, when we evaluated the effect on angiogenic mechanisms, the supernatant from tumor cells treated with doxorubicin exhibited a pro-angiogenic effect on endothelial cells. Hyaluronan-doxorubicin co-treatment increased migration and vessel formation in endothelial cells. This effect was independent of vascular endothelial growth factor but related to fibroblast growth factor-2 expression. Besides, we observed a pro-angiogenic effect on endothelial cells during hyaluronan and doxorubicin co-treatment in the in vivo murine model of T-cell lymphoma. Our results demonstrate for the first time that hyaluronan is a potential modulator of doxorubicin response by mechanisms that involve not only drug efflux but also angiogenic processes, providing an adverse tumor stroma during chemotherapy.

Abstract B178: 4-methylumbelliferone modulates tumor microenvironment improving the antitumor efficacy of combined gene-based immunotherapy in murine colon adenocarcinoma

The crosstalk involving immune cells subsets, the components of tumor microenvironment and cancer cells could positively result in the delaying of tumor progression. Then, the use of immunotherapy to generates or stimulates the antitumor immune response and inhibits tumor growth has become an interesting option, especially when is used as adjuvant, for many types of tumors. We have previously demonstrated that the administration of low-dose of cyclophosphamide (Cy), a chemotherapeutic agent able to eliminates the immunosuppression induced by tumors in combination with interleukin 12 based-gene therapy (AdIL-12) has a synergistic antitumoral effect leading to complete regression in 50% of tumors in a murine model of colon adenocarcinoma. The main mechanisms associated with the efficacy of combined therapy were the strongly reduction of CD4+CD25+Foxp3+ T cells and myeloid-derived suppressor cells and the induction of potent specific immune response mediated by cytotoxic interferon gamma (INF-gamma)-producing CD4+ T lymphocytes. Our current aims were to evaluate the effects of 4-methylumbelliferone (4Mu), a selective inhibitor of hyaluronan (HA) synthesis, on tumor microenvironment and to explore how 4Mu affects the therapeutic efficacy of Cy+AdIL-12. The results showed that 4Mu significantly reduced the amount of tumoral HA leading to a significant decrease in tumor interstitial pressure. Importantly, tumor perfusion was improved allowing an increase of adenoviral vector transfection. 4Mu therapy was also able to induce a significantly enhance of trafficking of specific antitumoral lymphocytes. Moreover, the administration of specific cytotoxic lymphocytes in 4Mu treated mice evidenced a potent inhibition on tumor growth. In association with these effects, the combination of 4Mu+Cy+AdIL-12 showed complete regression in more of 70% of tumors and mice treated with the triple combination significantly prolonged their survival. The use of 4Mu+Cy+AdIL-12 also induce a decrease in levels of pro-angiogenic factors such as Vascular Endothelial Growth Factor (VEGF), Hypoxia-inducible Factor 1-alpha (HIF 1-alpha) and interleukin 6 (IL-6), together with an increase of anti-angiogenic molecules (Trombospondin-1 (TSP-1) and Interferon-Inducible protein-10 (IP-10) in tumor milieu. Our results showed that tumor microenvironment remodeling is an interesting strategy to increase the efficacy of anticancer immunotherapies based on gene and/or cell therapy.

Note:This abstract was not presented at the conference.

Citation Format: Mariana Malvicini, Esteban Fiore, Valentina Ghiaccio, Flavia Piccioni, Miguel Rizzo, Mariana Garcia, Marcelo Rodriguez, Juan Bayo, Estanislao Peixoto, Catalina Atorrasagasti, Laura Alaniz, Pablo Matar, Guillermo Mazzolini. 4-methylumbelliferone modulates tumor microenvironment improving the antitumor efficacy of combined gene-based immunotherapy in murine colon adenocarcinoma. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B178.

[Dendritic cell-based therapeutic cancer vaccines]

In recent years immunotherapy has revolutionized the treatment of patients with advanced cancer. The increased knowledge in the tumor immune-biology has allowed developing rational treatments by manipulation of the immune system with significant clinical impact. This rapid development has significantly changed the prognosis of many tumors without treatment options up to date. Other strategies have explored the use of therapeutic vaccines based on dendritic cells (DC) by inducing antitumor immunity. DC are cells of hematopoietic origin, constitutively expressing molecules capable to present antigens, that are functionally the most potent inducers of the activation and proliferation of antigen specific T lymphocytes. The CD8+ T cells proliferate and acquire cytotoxic capacity after recognizing their specific antigen presented on the surface of DC, although only some types of DC can present antigens internalized from outside the cell to precursors of cytotoxic T lymphocytes (this function is called cross-presentation) requiring translocation mechanisms of complex antigens. The induction of an effective adaptive immune response is considered a good option given its specificity, and prolonged duration of response. The DC, thanks to its particular ability of antigen presentation and lymphocyte stimulation, are able to reverse the poor antitumor immune response experienced by patients with cancer. The DC can be obtained from various sources, using different protocols to generate differentiation and maturation, and are administered by various routes such as subcutaneous, intravenous or intranodal. The wide variety of protocols resulted in heterogeneous clinical responses.

Tumor Microenvironment Remodeling by 4-Methylumbelliferone Boosts the Antitumor Effect of Combined Immunotherapy in Murine Colorectal Carcinoma

We have previously demonstrated that a low dose of cyclophosphamide (Cy) combined with gene therapy of interleukin-12 (AdIL-12) has a synergistic, although limited, antitumoral effect in mice with colorectal carcinoma. The main mechanism involved in the efficacy of Cy+AdIL-12 was the induction of a specific immune response mediated by cytotoxic T lymphocytes. Our current aims were to evaluate the effects of 4-methylumbelliferone (4Mu), a selective inhibitor of hyaluronan (HA) synthesis, on tumor microenvironment (TME) and to investigate how 4Mu affects the therapeutic efficacy of Cy+AdIL-12. The results showed that 4Mu significantly reduced the amount of tumoral HA leading to a significant decrease in tumor interstitial pressure (TIP). As a consequence, tumor perfusion was improved allowing an increased adenoviral transgene expression. In addition, treatment with 4Mu boosted the number of cytotoxic T lymphocytes that reach the tumor after adoptive transfer resulting in a potent inhibition of tumor growth. Importantly, we observed complete tumor regression in 75% of mice when 4Mu was administrated in combination with Cy+AdIL-12. The triple combination 4Mu+Cy+AdIL-12 also induced a shift toward antiangiogenic factors production in tumor milieu. Our results showed that TME remodeling is an interesting strategy to increase the efficacy of anticancer immunotherapies based on gene and/or cell therapy.

4-methylumbelliferone inhibits hepatocellular carcinoma growth by decreasing IL-6 production and angiogenesis

Cirrhosis is characterized by an excessive accumulation of extracellular matrix components including hyaluronic acid (HA) and is widely considered a preneoplastic condition for hepatocellular carcinoma (HCC). 4-Methylumbelliferone (4MU) is an inhibitor of HA synthesis and has anticancer activity in an orthotopic HCC model with underlying fibrosis. Our aim was to explore the effects of HA inhibition by 4MU orally administered on tumor microenvironment. Hepa129 tumor cells were inoculated orthotopically in C3H/HeJ male mice with fibrosis induced by thioacetamide. Mice were orally treated with 4MU. The effects of 4MU on angiogenesis were evaluated by immunostaining of CD31 and quantification of proangiogenic factors (vascular endothelial growth factor, VEGF, interleukin-6, IL-6 and C-X-C motif chemokine 12, CXCL12). IL-6 was also quantified in Hepa129 cells in vitro after treatment with 4MU. Migration of endothelial cells and tube formation were also analyzed. As a result, 4MU treatment decreases tumor growth and increased animal survival. Systemic levels of VEGF were significantly inhibited in 4MU-treated mice. Expression of CD31 was reduced after 4MU therapy in liver parenchyma in comparison with control group. In addition, mRNA expression and protein levels of IL-6 and VEGF were inhibited both in tumor tissue and in nontumoral liver parenchyma. Interestingly, IL-6 production was dramatically reduced in Kupffer cells isolated from 4MU-treated mice, and in Hepa129 cells in vitro. Besides, 4MU was able to inhibit endothelial cell migration and tube formation. In conclusion, 4MU has antitumor activity in vivo and its mechanisms of action involve an inhibition of angiogenesis and IL-6 production. 4MU is an orally available molecule with potential for HCC treatment.

Mesenchymal stromal cells engineered to produce IGF-I by recombinant adenovirus ameliorate liver fibrosis in mice

Liver cirrhosis involves chronic wound healing and fibrotic processes. Mesenchymal stromal cells (MSCs) are multipotent adult progenitor cells that are used as vehicles of therapeutic genes. Insulin growth factor like-I (IGF-I) was shown to counteract liver fibrosis. We aimed at analyzing the effect of applying IGF-I overexpressing mouse bone marrow-derived MSCs on hepatic fibrosis. Fibrosis was induced by chronic thioacetamide application or bile duct ligation. MSCs engineered to produce green fluorescent protein (GFP) (AdGFP-MSCs) or IGF-I (AdIGF-I-MSCs) were applied systemically, and changes in collagen deposition and in the expression of key pro-fibrogenic and pro-regenerative genes/proteins were assessed. In addition, immunogenicity of transduced cells was analyzed. Liver fibrosis was further ameliorated after a single-dose application of AdIGF-I-MSCs when compared with AdGFP-MSCs and/or recombinant IGF-I treatments. Interestingly, an early and transitory upregulation in IGF-I and hepatocyte growth factor (HGF) mRNA expression was found in the liver of MSC-treated animals, which was more pronounced in AdIGF-I-MSCs condition. A reduction in hepatic stellate cell activation status was found after incubation with MSCs conditioned media. In addition, the AdIGF-I-MSCs cell-free supernatant induced the expression of IGF-I and HGF in primary cultured hepatocytes. From day 1 after transplantation, the proliferation marker proliferating cell nuclear antigen was upregulated in the liver of AdIGF-I-MSCs group, mainly in hepatocytes. MSCs were in vivo traced till day 14 after injection. In addition, multiple doses of Ad-IGF-I-MSCs likely suppressed antiviral immune response and it further reduced collagen deposition. Our results uncover early events that are likely involved in the anti-fibrogenic effect of genetically modified MSCs and overall would support the use of AdIGF-I-MSCs in treatment of liver fibrosis.

SPARC (secreted protein acidic and rich in cysteine) knockdown protects mice from acute liver injury by reducing vascular endothelial cell damage

Secreted protein, acidic and rich in cysteine (SPARC) is involved in many biological process including liver fibrogenesis, but its role in acute liver damage is unknown. To examine the role of SPARC in acute liver injury, we used SPARC knock-out (SPARC(-/-)) mice. Two models of acute liver damage were used: concanavalin A (Con A) and the agonistic anti-CD95 antibody Jo2. SPARC expression levels were analyzed in liver samples from patients with acute-on-chronic alcoholic hepatitis (AH). SPARC expression is increased on acute-on-chronic AH patients. Knockdown of SPARC decreased hepatic damage in the two models of liver injury. SPARC(-/-) mice showed a marked reduction in Con A-induced necroinflammation. Infiltration by CD4+ T cells, expression of tumor necrosis factor-α and interleukin-6 and apoptosis were attenuated in SPARC(-/-) mice. Sinusoidal endothelial cell monolayer was preserved and was less activated in Con A-treated SPARC(-/-) mice. SPARC knockdown reduced Con A-induced autophagy of cultured human microvascular endothelial cells (HMEC-1). Hepatic transcriptome analysis revealed several gene networks that may have a role in the attenuated liver damaged found in Con A-treated SPARC(-/-) mice. SPARC has a significant role in the development of Con A-induced severe liver injury. These results suggest that SPARC could represent a therapeutic target in acute liver injury.

Single low-dose cyclophosphamide combined with interleukin-12 gene therapy is superior to a metronomic schedule in inducing immunity against colorectal carcinoma in mice

The use of conventional cytotoxic agents at metronomic schedules, alone or in combination with targeted agents or immunotherapy, is being explored as a promising anticancer strategy. We previously reported a potent antitumor effect of a single low-dose cyclophosphamide and interleukin-12 (IL-12) gene therapy against advanced gastrointestinal carcinoma, in mice. Here, we assessed whether the delivery of IL-12 by gene therapy together with metronomic cyclophosphamide exerts antitumor effects in a murine model of colorectal carcinoma. This combination therapy was able, at least in part, to reverse immunosuppression, by decreasing the number of regulatory T cells (Tregs) as well as of splenic myeloid-derived suppressor cells (MDSCs). However, metronomic cyclophosphamide plus IL-12 gene therapy failed to increase the number of tumor-infiltrating T lymphocytes and, more importantly, to induce a specific antitumor immune response. With respect to this, cyclophosphamide at a single low dose displayed a superior anticancer profile than the same drug given at a metronomic schedule. Our results may have important implications in the design of new therapeutic strategies against colorectal carcinoma using cyclophosphamide in combination with immunotherapy.

Low molecular weight hyaluronan-pulsed human dendritic cells showed increased migration capacity and induced resistance to tumor chemoattraction

We have shown that ex vivo pre-conditioning of bone marrow-derived dendritic cells (DC) with low molecular weight hyaluronan (LMW HA) induces antitumor immunity against colorectal carcinoma (CRC) in mice. In the present study we investigated the effects of LMW HA priming on human-tumor-pulsed monocytes-derived dendritic cells (DC/TL) obtained from healthy donors and patients with CRC. LMW HA treatment resulted in an improved maturation state of DC/TL and an enhanced mixed leucocyte reaction activity in vivo. Importantly, pre-conditioning of DC/TL with LMW HA increased their ability to migrate and reduced their attraction to human tumor derived supernatants. These effects were associated with increased CCR7 expression levels in DC. Indeed, a significant increase in migratory response toward CCL21 was observed in LMW HA primed tumor-pulsed monocyte-derived dendritic cells (DC/TL/LMW HA) when compared to LWM HA untreated cells (DC/TL). Moreover, LMW HA priming modulated other mechanisms implicated in DC migration toward lymph nodes such as the metalloproteinase activity. Furthermore, it also resulted in a significant reduction in DC migratory capacity toward tumor supernatant and IL8 in vitro. Consistently, LMW HA dramatically enhanced in vivo DC recruitment to tumor-regional lymph nodes and reduced DC migration toward tumor tissue. This study shows that LMW HA--a poorly immunogenic molecule--represents a promising candidate to improve human DC maturation protocols in the context of DC-based vaccines development, due to its ability to enhance their immunogenic properties as well as their migratory capacity toward lymph nodes instead of tumors.

Increased migration of human mesenchymal stromal cells by autocrine motility factor (AMF) resulted in enhanced recruitment towards hepatocellular carcinoma

Background and Aims

Several reports described the migration of human mesenchymal stromal cells (MSCs) towards tumor-released factors. Autocrine motility factor (AMF) is produced by several tumors including hepatocellular carcinoma (HCC). The aim of this study was to analyze AMF involvement on MSC migration towards human HCC.

Methods

Production of AMF by HCC tumors was evaluated by western analysis. The effects of AMF on MSCs from different sources (bone marrow, adipose tissue and perivascular cells from umbilical cord) were analyzed using in vitro migration assay; metalloproteinase 2 (MMP2) activity and expression of critical genes were studied by zymography and qRT-PCR, respectively. To assess AMF involvement on the in vivo MSC migration, noninvasive fluorescence imaging was performed. To test the effect of AMF-primed MSCs on tumor development, in vitro proliferation and spheroids growth and in vivo tumor volume were evaluated.

Results

AMF produced by HCC was found to induce migration of different MSCs in vitro and to enhance their MMP2 activity. Stimulation of MSCs with recombinant AMF (rAMF) also induced the in vitro adhesion to endothelial cells in coincidence with changes in the expression levels of MMP3, AMF receptor, caveolin-1, and -2 and GDI-2. Importantly, stimulation of MSCs with rAMF increased the in vivo migration of MSCs towards experimental HCC tumors. AMF-priming of MSCs did not induce a pro-tumorigenic effect on HCC cells neither in vivo nor in vitro.

Conclusion

AMF plays a role in MSC recruitment towards HCC. However, its ability to increase MSC migration to HCC for therapeutic purposes merits further evaluation.

Pulsing dendritic cells with whole tumor cell lysates

One of the strategies employed in immunotherapy for cancer is to use of ex vivo-generated dendritic cells (DC) pulsed with tumor antigens. Several approaches have been used to obtain and load tumor antigens in DC. One such technique is to use whole tumor cell lysate from one or more tumor cell lines of the tumor type to be treated. The advantage of applying this method is that it provides a large spectrum of tumor antigens. However, some considerations must be taken into account to obtain a lysate with appropriate biological activity, such as cell line harvest and the method to lyse the cells. In this chapter, we describe the steps to obtain whole tumor cell lysates from human tumor cell lines by repetitive freeze-thaw cycles in sufficient amount and quality to pulse DC.

Ex vivo loading of autologous dendritic cells with tumor antigens

Ex vivo-generated antigen-loaded dendritic cells (DC) have been shown to be immunogenic in patients with cancer. Loading DC with autologous whole tumor antigens is a strategy to arm DC against tumor without human leukocyte antigen (HLA) restriction. Furthermore, this approach allows the presentation of a full antigen range to the immune system. We describe the methods to obtain whole antigens from autologous tumor tissues in order to load DC generated ex vivo from patients with gastrointestinal cancer.

Anti-tumor effect of SLPI on mammary but not colon tumor growth

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that was related to cancer development and metastasis dissemination on several types of tumors. However, it is not known the effect of SLPI on mammary and colon tumors. The aim of this study was to examine the effect of SLPI on mammary and colon tumor growth. The effect of SLPI was tested on in vitro cell apoptosis and in vivo tumor growth experiments. SLPI over-expressing human and murine mammary and colon tumor cells were generated by gene transfection. The administration of murine mammary tumor cells over-expressing high levels of SLPI did not develop tumors in mice. On the contrary, the administration of murine colon tumor cells over-expressing SLPI, developed faster tumors than control cells. Intratumoral, but not intraperitoneal administration of SLPI, delayed the growth of tumors and increased the survival of mammary but not colon tumor bearing mice. In vitro culture of mammary tumor cell lines treated with SLPI, and SLPI producer clones were more prone to apoptosis than control cells, mainly under serum deprivation culture conditions. Herein we demonstrated that SLPI induces the apoptosis of mammary tumor cells in vitro and decreases the mammary but not colon tumor growth in vivo. Therefore, SLPI may be a new potential therapeutic tool for certain tumors, such as mammary tumors.

Low molecular weight hyaluronan preconditioning of tumor-pulsed dendritic cells increases their migratory ability and induces immunity against murine colorectal carcinoma

We have recently shown that systemic administration of low molecular weight hyaluronan (LMW HA) significantly reduces colorectal carcinoma (CRC) growth in vivo. The elicited response is partially mediated by activated dendritic cells (DC). To potentiate the ability of DC loaded with whole tumor lysate (DC/TL) to induce immunity against CRC in mice, we aimed to study the effects of preconditioning DC with LMW HA for therapeutic vaccination. LMW HA improved maturation of ex vivo generated DC, increased IL-12, decreased IL-10 production, and enhanced a MLR activity in vitro. Although TNF-α showed a similar capacity to mature DC, preconditioning of DC/TL with LMW HA increased their ability to migrate in vitro toward CCL19 and CCL-21 in a CD44- and a TLR4-independent manner; this effect was superior to Poly(I:C), LPS, or TNF-α and partially associated with an increase in the expression of CCR7. Importantly, LMW HA dramatically enhanced the in vivo DC recruitment to tumor-regional lymph nodes. When these LMW HA-treated CRC tumor lysate-pulsed DC (DC/TL/LMW HA) were administered to tumor-bearing mice, a potent antitumor response was observed when compared to DC pulsed with tumor lysate alone and matured with TNF-α. Then, we showed that splenocytes isolated from animals treated with DC/TL/LMW HA presented a higher proliferative capacity, increased IFN-γ production, and secreted lower levels of the immunosuppressive IL-10. Besides, increased specific CTL response was observed in DC/TL/LMW HA-treated animals and induced long-term protection against tumor recurrence. Our data show that LMW HA is superior to other agents at inducing DC migration; therefore, LMW HA could be considered a new adjuvant candidate in the preparation of DC-based anticancer vaccines with potent immunostimulatory properties.

Hepatocellular carcinoma cells and their fibrotic microenvironment modulate bone marrow-derived mesenchymal stromal cell migration in vitro and in vivo

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third cause of cancer-related death. Fibrogenesis is an active process characterized by the production of several proinflammatory cytokines, chemokines and growth factors. It involves the activation of hepatic stellate cells (HSCs) which accumulate at the site of injury and are the main source of the extracellular matrix deposits. There are no curative treatments for advanced HCC, thus, new therapies are urgently needed. Mesenchymal stromal cells (MSCs) have the ability to migrate to sites of injury or to remodeling tissues after in vivo administration; however, in several cancer models they demonstrated limited efficacy to eradicate experimental tumors partially due to poor engraftment. Thus, the aim of this work was to analyze the capacity of human MSCs (hMSCs) to migrate and anchor to HCC tumors. We observed that HCC and HSCs, but not nontumoral stroma, produce factors that induce hMSC migration in vitro. Conditioned media (CM) generated from established HCC cell lines were found to induce higher levels of hMSC migration than CM derived from fresh patient tumor samples. In addition, after exposure to CM from HCC cells or HSCs, hMSCs demonstrated adhesion and invasion capability to endothelial cells, type IV collagen and fibrinogen. Consistently, these cells were found to increase metalloproteinase-2 activity. In vivo studies with subcutaneous and orthotopic HCC models indicated that intravenously infused hMSCs migrated to lungs, spleen and liver. Seven days post-hMSC infusion cells were located also in the tumor in both models, but the signal intensity was significantly higher in orthotopic than in subcutaneous model. Interestingly, when orthotopic HCC tumors where established in noncirrhotic or cirrhotic livers, the amount of hMSCs localized in the liver was higher in comparison with healthy animals. A very low signal was found in lungs and spleens, indicating that liver tumors are able to recruit them at high efficiency. Taken together our results indicate that HCC and HSC cells produce factors that efficiently induce hMSC migration toward tumor microenvironment in vitro and in vivo and make MSCs candidates for cell-based therapeutic strategies to hepatocellular carcinoma associated with fibrosis.

SPARC downregulation attenuates the profibrogenic response of hepatic stellate cells induced by TGF-β1 and PDGF

Liver fibrosis is an active process that involves changes in cell-cell and cell-extracellular matrix (ECM) interaction. Secreted protein, acidic and rich in cysteine (SPARC) is an ECM protein with many biological functions that is overexpressed in cirrhotic livers and upregulated in activated hepatic stellate cells (aHSCs). We have recently shown that SPARC downregulation ameliorates liver fibrosis in vivo. To uncover the cellular mechanisms involved, we have specifically knocked down SPARC in two aHSC lines [the CFSC-2G (rat) and the LX-2 (human)] and in primary cultured rat aHSCs. Transient downregulation of SPARC in hepatic stellate cells (HSCs) did not affect their proliferation and had only minor effects on apoptosis. However, SPARC knockdown increased HSC adhesion to fibronectin and significantly decreased their migration toward PDFG-BB and TGF-β(1). Interestingly, TGF-β(1) secretion by HSCs was reduced following SPARC small interfering RNA (siRNA) treatment, and preincubation with TGF-β(1) restored the migratory capacity of SPARC siRNA-treated cells through mechanisms partially independent from TGF-β(1)-mediated induction of SPARC expression; thus SPARC knockdown seems to exert its effects on HSCs partially through modulation of TGF-β(1) expression levels. Importantly, collagen-I mRNA expression was reduced in SPARC siRNA-transfected HSCs. Consistent with previous results, SPARC knockdown in aHSCs was associated with altered F-actin expression patterns and deregulation of key ECM and cell adhesion molecules, i.e., downregulation of N-cadherin and upregulation of E-cadherin. Our data together suggest that the upregulation of SPARC previously reported for aHSCs partially mediates profibrogenic activities of TGF-β(1) and PDGF-BB and identify SPARC as a potential therapeutic target for liver fibrosis.

Reversal of gastrointestinal carcinoma-induced immunosuppression and induction of antitumoural immunity by a combination of cyclophosphamide and gene transfer of IL-12

Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic doses of an adenovirus expressing IL-12 genes (AdIL-12) mediated a potent antitumour effect against subcutaneous (s.c.) colorectal carcinomas (CRC) in mice pre-treated with low doses of cyclophosphamide (Cy). In our study we used this combination to assess its impact on the immunosuppressive microenvironment. In s.c. CRC model we demonstrated that non-responder mice failed to decrease Tregs in tumour, spleen and peripheral blood. Reconstitution of Tregs into tumour-bearing mice treated with combined therapy abolished the antitumoural effect. In addition, Cy + AdIL-12 modified Tregs functionality by inhibiting the in vitro secretion of IL-10 and TGF-β and their ability to inhibit dendritic cells activation. Combined treatment decreased the number of myeloid-derived suppressor cells (MDSCs) in comparison to non-treated mice and, interestingly, administration of Tregs restored splenic MDSCs population. Furthermore, combined therapy potently generated specific cytotoxic IFN-γ-secreting CD4+ T cells able to eradicate established CRC tumours after adoptive transfer. Finally, we evaluated the combination on disseminated CRC and pancreatic carcinoma (PC). Cy + AdIL-12 were able to eradicate liver metastatic CRC (47%) and PC tumour nodules (40%) and to prolong animal survival. The results of this study support the hypothesis that Cy + AdIL-12 might be a valid immunotherapeutic strategy for advanced GIC.

Overexpression of SPARC obliterates the in vivo tumorigenicity of human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third leading cause of cancer-related death worldwide. Current treatments are extremely disappointing. SPARC (Secreted protein, acidic and rich in cysteine) is a matricellular glycoprotein with differential expression in several tumors, including HCC, which significance remains unclear. We infected HCC cells (HepG2, Hep3B and Huh7) with an adenovirus expressing SPARC (AdsSPARC) to examine the role of SPARC expression on HCC cells and its effect on tumor aggressiveness. The in vitro HCC cells substrate-dependent proliferation and cell cycle profile were unaffected; however, SPARC overexpression reduced HCC proliferation when cells were grown in spheroids. A mild induction of cellular apoptosis was observed upon SPARC overexpression. SPARC overexpression resulted in spheroid growth inhibition in vitro while no effects were found when recombinant SPARC was exogenously applied. Moreover, the clonogenic and migratory capabilities were largely decreased in SPARC-overexpressing HCC cells, altogether suggesting a less aggressive HCC cell phenotype. Consistently, AdsSPARC-transduced cells showed increased E-cadherin expression and a concomitant decrease in N-cadherin expression. Furthermore, SPARC overexpression was found to reduce HCC cell viability in response to 5-FU-based chemotherapy in vitro, partially through induction of apoptosis. In vivo experiments revealed that SPARC overexpression in HCC cells inhibited their tumorigenic capacity and increased animal survival through a mechanism that partially involves host macrophages. Our data suggest that SPARC overexpression in HCC cells results in a reduced tumorigenicity partially through the induction of mesenchymal-to-epithelial transition (MET). These evidences point to SPARC as a novel target for HCC treatment.

A novel synergistic combination of cyclophosphamide and gene transfer of interleukin-12 eradicates colorectal carcinoma in mice

PURPOSE

Interleukin-12 (IL-12) is an immunostimulatory cytokine with potent antitumor effects in several animal models. However, serious toxicity has been associated with its systemic application in humans. Gene transfer has emerged as a tool to specifically express therapeutic genes into the tumor/peritumoral milieu, thus avoiding systemic toxicity. The aim of this study was to analyze whether subtherapeutic doses of an adenovirus encoding IL-12 (AdIL-12) might synergize with low immunopotentiating doses of cyclophosphamide in the treatment of colorectal carcinoma.

EXPERIMENTAL DESIGN

The antitumor effect of combining a single low dose of cyclophosphamide with an intratumoral injection of AdIL-12 was evaluated in an in vivo murine colorectal carcinoma model. The immune responses achieved with different treatments were monitored, comparing the effect of combining both therapies with individual treatments.

RESULTS

The combined therapy induced a complete tumor regression in >50% of mice in a synergistic fashion, and it significantly prolonged their survival. This strategy was superior to each single treatment in reducing both peripheral and splenic CD4+CD25+Foxp3+ regulatory T cells, increasing the number of activated dendritic cells, and inducing IFN-gamma-secreting CD4-positive T lymphocytes. Importantly, the combined treatment generated a powerful tumor-specific CTL response. Consistently, a significant reduction in IL-10 levels was found. Our data suggest that the combination of nontoxic doses of cyclophosphamide with AdIL-12 allows the generation of good antitumoral responses, thus avoiding undesired side effects of both agents.

CONCLUSIONS

Our data strongly support the use of a combination of cyclophosphamide and AdIL-12 as a novel therapeutic strategy against colorectal carcinoma.

Immunotherapy for liver tumors: present status and future prospects

Increasing evidence suggests that immune responses are involved in the control of cancer and that the immune system can be manipulated in different ways to recognize and attack tumors. Progress in immune-based strategies has opened new therapeutic avenues using a number of techniques destined to eliminate malignant cells. In the present review, we overview current knowledge on the importance, successes and difficulties of immunotherapy in liver tumors, including preclinical data available in animal models and information from clinical trials carried out during the lasts years. This review shows that new options for the treatment of advanced liver tumors are urgently needed and that there is a ground for future advances in the field.

Adenovirus-mediated inhibition of SPARC attenuates liver fibrosis in rats

BACKGROUND

The interaction between fibrogenic cells and extracellular matrix plays a role in liver fibrosis, yet the mechanisms are largely unknown. Secreted protein, acidic and rich in cysteine (SPARC) is a matricellular glycoprotein that is expressed by hepatic stellate cells and is overexpressed in fibrotic livers. We investigated the in vivo role of SPARC in experimentally induced liver fibrosis in rats.

METHODS

A recombinant adenovirus carrying antisense SPARC was constructed (AdasSPARC). Advanced liver fibrosis was induced in Sprague-Dawley rats by prolonged intraperitoneal administration of thioacetamide. Animals received injections of AdasSPARC or Ad beta gal (control adenovirus) via the tail vein and directly into the liver 1 week after the first dose. The pathological changes in liver tissues and indices of fibrosis were assessed at eight weeks. Expression of SPARC, transforming growth factor (TGF)-beta and alpha-smooth muscle actin were evaluated by quantitative real-time polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

Hepatic SPARC expression significantly increased during the development of liver fibrosis. AdasSPARC markedly attenuated the development of hepatic fibrosis in rats treated with thiocetamide, as assessed by decreased collagen deposition, lower hepatic content of hydroxyproline and less advanced morphometric stage of fibrosis. AdasSPARC treatment reduced inflammatory activity (Knodell score) and suppressed transdifferentiation of hepatic stellate cell to the myofibroblasts like phenotype in vivo. Furthermore, in vitro inhibition of SPARC on hepatic stellate cells decreases the production of TGF-beta.

CONCLUSIONS

This is the first study to demonstrate that knockdown of hepatic SPARC expression ameliorates thioacetamide-induced liver fibrosis in rats with chronic liver injury. SPARC is a potential target for gene therapy in liver fibrosis.

Hyaluronan oligosaccharides sensitize lymphoma resistant cell lines to vincristine by modulating P-glycoprotein activity and PI3K/Akt pathway

Multidrug resistance (MDR) is one of the main reasons for failure of cancer therapy. It may be mediated by overexpression of ATP-dependent efflux pumps or by alterations in survival or apoptotic pathways. Fragments generated by enzymatic degradation of hyaluronan (oHA) were able to modulate growth and cell survival and sensitize MDR breast cancer cells to cytotoxic drugs. In this work the relationship between oHA and MDR in lymphoid malignancies was analyzed using murine lymphoma cell lines resistant to doxorubicin (LBR-D160) or vincristine (LBR-V160) and a sensitive line (LBR-). After oHA treatment, higher apoptosis levels were observed in the resistant cell lines than in the sensitive one. Besides, oHA sensitized LBR-D160 and LBR-V160 to vincristine showing increased apoptosis induction when used in combination with vincristine. Native hyaluronan failed to increase apoptosis levels. As different survival factors could be modulated by hyaluronan, we investigated the PI3K/Akt pathway through PIP3 production and phosphorylated Akt (p-Akt) and survivin expression was also evaluated. Our results showed that oHA decreased p-Akt in the 3 cell lines while anti-CD44 treatment abolished this effect. Besides, survivin was downregulated only in LBR-V160 by oHA. When Pgp function was evaluated, we observed that oHA were able to inhibit Pgp efflux in murine and human resistant cell lines in a CD44-dependent way. In summary, we report for the first time that oHA per se modulate MDR in lymphoma cells by decreasing p-Akt as well as Pgp activity, thus suggesting that oHA could be useful in combination with classical chemotherapy in MDR hematological malignancies.

Hyaluronan oligosaccharides induce cell death through PI3-K/Akt pathway independently of NF-κB transcription factor

Several studies indicate that hyaluronan oligosaccharides (oHA) are able to modulate growth and cell survival in solid tumors; however, no studies have been undertaken to analyze the effect of oHA on T-lymphoid disorders. In this work we showed that oHA were able to induce apoptosis in lymphoma cell lines. Since PI3-K/Akt and nuclear factor-kappaB (NF-kappaB) are major factors involved in cell survival and anti-apoptotic pathways in lymphoma cells, we hypothesized that oHA could induce apoptosis through inhibition of these pathways. oHA were identified by a method which allows characterization of length using a high pH anion exchange chromatography with pulse amperometric detection (HPAEC-PAD). oHA inhibited PIP(3) production (principal product of PI3-K activity) and reduced Akt phosphorylation levels, similarly to the specific inhibitor wortmannin. However, treatment with either oHA or wortmannin failed to inhibit constitutive NF-kappaB activity and modulate IkappaBalpha protein levels, suggesting that PI3-K and NF-kappaB signaling pathways are not related in the cell lines used. Cell behavior differed using native hyaluronan (HA), which induced PIP(3) production, Akt phosphorylation, and NF-kappaB activation, although not related with cell survival since treatment with native HA showed no effect on apoptosis. Our results suggest that oHA induce apoptosis by suppression of PI3-K/Akt cell survival pathway without involving NF-kappaB activation, through a mechanism that differs from the one mediated by native HA.

Inhibition of NF-kappaB activity by BAY 11-7082 increases apoptosis in multidrug resistant leukemic T-cell lines

Multidrug resistance (MDR) is the main reason for failure of cancer therapy with resistance to apoptosis being one of the mechanisms involved. Constitutive NF-kappaB activity has been detected in many tumors contributing to oncogenesis and tumor survival whereas inhibition of NF-kappaB activity has proved to enhance cell death induced by chemotherapeutic agents. Consequently, the use of BAY 11-7082, an irreversible inhibitor of IkappaB-alpha phosphorylation, could be beneficial in the treatment of certain tumors. Although there are several reports which demonstrate a transient activation of NF-kappaB by cytotoxic drugs, little is known about the role of NF-kappaB activation in the development of a chemoresistant phenotype in leukemic cells. In this study, we analyzed the relationship between NF-kappaB and the survival of murine leukemic drug resistant cell lines. The modulation of this transcription factor by BAY 11-7082 and the chemotherapeutic agents vincristine and doxorubicin was evaluated. The effect of BAY 11-7082 on the expression of genes containing NF-kappaB-binding sites was also studied. We found that the cell lines LBR-V160 and LBR-D160 (resistant to vincristine and doxorubicin, respectively) presented higher constitutive NF-kappaB activity than the sensitive LBR- and the active complex contained both p50 and p65 subunits. BAY 11-7082 (3.5 microM) inhibited constitutive NF-kappaB activity in the three cell lines whereas the anticancer agents did not. Treatment with BAY 11-7082 induced a higher percentage of apoptosis in LBR-V160 and LBR-D160 than in LBR-. Cells treated with BAY 11-7082 displayed modulation of NF-kappaB-inducible genes such as IL-10, IL-15, TNF-alpha and TGF-beta. Taken together, these data suggest that suppression of constitutive NF-kappaB activity by BAY 11-7082 may be a useful treatment for MDR leukemias.

CD44 and hyaluronic acid regulate in vivo iNOS expression and metalloproteinase activity in murine air-pouch inflammation

OBJECTIVE

To evaluate the effects of anti-CD44 IM7.8.1 antibody, HMW-HA and LMW-HA on leukocyte migration and adhesion, and the induction of proinflammatory mediators, in mouse air-pouch inflammation induced by zymosan.

METHODS

Leukocytes were obtained from zymosan-air pouches after the intra-pouch injection of anti-CD44 IM7.8.1, isotype control, HMW-HA, LMW-HA or PBS. TNF-alpha, IL-1beta and iNOS mRNA were estimated in leukocytes by semi-quantitative RT-PCR. Matrix metalloproteinases (MMPs) from exudates were evaluated by zymography and Western Blot. Adhesion and migration of leukocytes were evaluated in HA-coated plates and Boyden chambers respectively.

RESULTS

IM7.8.1 decreased iNOS mRNA levels and the activity of both MMP-9 and MMP-2 eight h after injection into zymosan air pouch while IM7.8.1, HMW-HA and LMW-HA had no effect on IL1-beta or TNF-alpha mRNA levels. Leukocytes from air pouch adhered to and migrated in vitro against both HMW-HA and LMW-HA. LMW-HA increased the number of leukocytes in the air pouch and iNOS mRNA levels as compared to PBS injection. In contrast, HMW-HA decreased leukocyte count and reduced iNOS mRNA levels. Paradoxically, the activity of both MMP-9 and MMP-2 was increased by HMW-HA and decreased by LMW-HA.

CONCLUSIONS

Both CD44 and HA can modulate leukocyte migration and induction of proinflammatory mediators in mouse zymosan air pouch inflammation. IM7.8.1 had consistent anti-inflammatory effects, reducing iNOS, MMP-9 and MMP-2. HMW-HA and LMW-HA were able to modulate both the induction of proinflammatory mediators and leukocyte count in the air pouch.

Modulation of matrix metalloproteinase-9 activity by hyaluronan is dependent on NF-kappaB activity in lymphoma cell lines with dissimilar invasive behavior

Expression and activity of matrix metalloproteinase-9 (MMP-9) as well as its relationship with hyaluronan (HA) and NF-kappaB activity were analyzed in two murine lymphoma cell lines with dissimilar migration and invasive behavior. MMP activity was evaluated by zymograms in supernatants, membrane extracts of tumor cells, and in the organs invaded by these cells. The more aggressive LBLa cell line showed MMP-9 activity in vitro, which increased after HA treatment and was blocked by anti-CD44 mAb. Such activity was not found in the less aggressive LBLc. MMP-9 and MMP-2 activity was found in organs invaded by both cell lines, although differential MMP-9 activity was observed in lung infiltrated only by LBLa cell line. NF-kappaB activation was evaluated to determine whether differential activity of MMP-9 was dependent on downstream signaling pathway, showing higher NF-kappaB activity in the more aggressive LBLa cell line. Our results showed that MMP-9 activity modulated by HA through NF-kappaB signaling pathway may be involved in the aggressive behavior of LBLa.

Interaction of CD44 with different forms of hyaluronic acid. Its role in adhesion and migration of tumor cells

Interaction between hyaluronic acid (HA) and CD44 has been considered a key event in tumor invasion and metastasis. HA is a linear, high molecular weight glycosaminoglycan in its native state, but fragmented low molecular forms are found at sites ofneoplastic or inflammatory infiltrates. Both high and low molecular weights HA are involved in diverse biological functions. In this study, we used two clonal variants of a T cell murine lymphoma designated LBLa and LBLc. These cell lines were found to differ in their in vivo and in vitro growth rates. LBLa grew faster and exhibited an enhanced invasive capacity as compared to LBLc. In contrast, cell lines did not differ in the expression of surface markers (CD8, CD24, CD25, CD44, and CD18), or in their capacity to bind HA. However, LBLa cells exhibited higher capacity to migrate to low molecular weight HA than did LBLc. Migration was mediated by CD44 since it was abrogated by anti-CD44 monoclonal antibody as well as by hyaluronidase. We suggest that interaction between CD44 and low molecular weight HA may trigger migration mechanisms in LBLa cells, thus contributing to enhanced invasive cell capacity.