Overexpression of matriptase in tumor stroma is a poor prognostic indicator of extrahepatic bile duct cancer.

Bile duct cancer is known to contain numerous fibroblasts, and reported to recruit cancer- associated fibroblasts by secreting platelet-derived growth factor-D (PDGF-D) which needs serine proteases, such as matriptase, to behave as a ligand. However, their expression pattern, and prognostic value have not been clarified. In this study, we investigated the clinicopathological significance of PDGF-D and matriptase expression in patients with extrahepatic bile duct cancer. The samples were obtained from 256 patients who underwent the surgical resection between 1991 and 2015, and the expression levels of PDGF-D and matriptase were evaluated immunohistochemically. Staining intensities and distribution were scored, and finally classified into low and high expression groups in cancer cells and stroma respectively. High expression of matriptase in the cancer stroma was detected in 91 tumors (40%). The high stromal matriptase expression was significantly associated with shorter recurrence-free survival (RFS) and overall survival (OS) (P = 0.0027 and 0.0023, respectively). Multivariate analyses also demonstrated that the stromal matriptase expression level was an independent influential factor in RFS (P = 0.0050) and OS (P = 0.0093). Our findings suggest that the high stromal matriptase expression was strongly associated with tumor progression, recurrence and poor outcomes in patients with extrahepatic bile duct cancer.

TIM-3 Engagement Promotes Effector Memory T Cell Differentiation of Human Antigen-Specific CD8 T Cells by Activating mTORC1.

T cell expression of TIM-3 following Ag encounter has been associated with a continuum of functional states ranging from effector memory T cells to exhaustion. We have designed an in vitro culture system to specifically address the impact of anti-TIM-3/TIM-3 engagement on human Ag-specific CD8 T cells during a normal response to Ag and found that anti-TIM-3 treatment enhances T cell function. In our in vitro T cell culture system, MART1-specific CD8 T cells were expanded from healthy donors using artificial APCs. To ensure that the T cells were the only source of TIM-3, cells were rechallenged with peptide-loaded artificial APCs in the presence of anti-TIM-3 Ab. In these conditions, anti-TIM-3 treatment promotes generation of effector T cells as shown by acquisition of an activated phenotype, increased cytokine production, enhanced proliferation, and a transcription program associated with T cell differentiation. Activation of mTORC1 has been previously demonstrated to enhance CD8 T cell effector function and differentiation. Anti-TIM-3 drives CD8 T cell differentiation through activation of the mTORC1 as evidenced by increased levels of phosphorylated S6 protein and rhebl1 transcript. Altogether these findings suggest that anti-TIM-3, together with Ag, drives differentiation in favor of effector T cells via the activation of mTOR pathway. To our knowledge, this is the first report demonstrating that TIM-3 engagement during Ag stimulation directly influences T cell differentiation through mTORC1.

El caseinato de sodio incrementa número de linfocitos B en ratones.

Introducción. El caseinato de sodio, una sal de la caseína utilizada como agente proinflamatorio en ratones, es capaz de inducir granulopoyesis en vivo e incrementar la producción de citocinas esenciales en dicho evento.Objetivo. Evaluar si el caseinato de sodio es capaz de inducir un efecto biológico en células de origen linfoide y la producción de citocinas involucradas con este linaje.Materiales y métodos: Se utilizaron ratones hembra BALB/c de 8 a 12 semanas de edad. Los animales se inyectaron cuatro veces, con intervalos de 48 horas, por vía intraperitoneal con 1 ml de caseinato de sodio (10 % de SFB p/v). La población de linfocitos B y la incorporación de bromodesoxiuridina (BrdU) se analizaron mediante citometría de flujo. La detección de la interleucina 7 se evaluó mediante la técnica de ELISA.Resultados. Tras la inyección por vía intraperitoneal, el número de linfocitos B 220+ provenientes del bazo de ratones tratados con caseinato de sodio aumentó comparados con los que solo recibieron el vehículo como tratamiento (89,01±1,03 Vs. 75,66±2,08), así como la incorporación de BrdU en células B220+ (38,59±4,48 Vs. 11,82±1,04). Se evidenció, asimismo, el incremento en la concentración de la interleucina 7 (IL-7) en el suero de los ratones tratados con caseinato de sodio, comparados con los que solo recibieron el vehículo (62,1±17,5 Vs. 26,9±4,4 pg/ml).Conclusión. El caseinato de sodio fue capaz de aumentar el número de linfocitos B en bazo de ratones, así como inducir la producción de IL-7, citocina clave para la linfopoyesis B.

PDGF-CC underlies resistance to VEGF-A inhibition and combinatorial targeting of both suppresses pathological angiogenesis more efficiently.

Anti-VEGF-A therapy has proven to be effective for many neovascular diseases. However, drug resistance to anti-VEGF-A treatment can develop. Also, not all patients with neovascular diseases are responsive to anti-VEGF-A treatment. The mechanisms underlying these important issues remain unclear. In this study, using different model systems, we found that inhibition of VEGF-A directly upregulated PDGF-CC and its receptors in multiple cell types in pathological angiogenesis in vitro and in vivo. Importantly, we further revealed that combinatorial targeting of VEGF-A and PDGF-CC suppressed pathological angiogenesis more efficiently than monotherapy. Given the potent angiogenic activity of PDGF-CC, our findings suggest that the development of resistance to anti-VEGF-A treatment may be caused by the compensatory upregulation of PDGF-CC, and combined inhibition of VEGF-A and PDGF-CC may have therapeutic advantages in treating neovascular diseases.

Ectosomes from neutrophil-like cells down-regulate nickel-induced dendritic cell maturation and promote Th2 polarization.

DCs are the first immune cells to be exposed to allergens, including chemical sensitizers, such as nickel, a human TLR4 agonist that induces DC maturation. In ACD, DCs can interact with PMNs that are recruited and activated, leading, in particular, to ectosome release. The objective of this work was to characterize the effects of PMN-Ect on DC functions in an ACD context. We first developed a standardized protocol to produce, characterize, and quantify ectosomes by use of human PLB-985 cells, differentiated into mature PMN (PLB-Ect). We then studied the in vitro effects of these purified ectosomes on human moDC functions in response to NiSO4 and to LPS, another TLR4 agonist. Confocal fluorescence microscopy showed that PLB-Ect was internalized by moDCs and localized in the lysosomal compartment. We then showed that PLB-Ect down-regulated NiSO4-induced moDC maturation, as witnessed by decreased expression of CD40, CD80, CD83, CD86, PDL-1, and HLA-DR and by decreased levels of IL-1ß, IL-6, TNF-α, and IL-12p40 mRNAs. These effects were related to p38MAPK and NF-κB down-regulation. However, no increase in pan-regulatory DC marker genes (GILZ, CATC, C1QA) was observed; rather, levels of effector DC markers (Mx1, NMES1) were increased. Finally, when these PLB-Ect + NiSO4-treated moDCs were cocultured with CD4(+) T cells, a Th2 cytokine profile seemed to be induced, as shown, in particular, by enhanced IL-13 production. Together, these results suggest that the PMN-Ect can modulate DC maturation in response to nickel, a common chemical sensitizer responsible for ADC.

Functional regulation of adipose-derived stem cells by PDGF-D.

Platelet-derived growth factor-D (PDGF-D) was recently identified, and acts as potent mitogen for mesenchymal cells. PDGF-D also induces cellular transformation and promotes tumor growth. However, the functional role of PDGF-D in adipose-derived stem cells (ASCs) has not been identified. Therefore, we primarily investigated the autocrine and paracrine roles of PDGF-D in this study. Furthermore, we identified the signaling pathways and the molecular mechanisms involved in PDGF-D-induced stimulation of ASCs. It is of interest that PDGF-B is not expressed, but PDGF-D and PDGF receptor-ß are expressed in ASCs. PDGF-D showed the strongest mitogenic effect on ASCs, and PDGF-D regulates the proliferation and migration of ASCs through the PI3K/Akt pathways. PDGF-D also increases the proliferation and migration of ASCs through generation of mitochondrial reactive oxygen species (mtROS) and mitochondrial fission. mtROS generation and fission were mediated by p66Shc phosphorylation, and BCL2-related protein A1 and Serpine peptidase inhibitor, clade E, member 1 mediated the proliferation and migration of ASCs. In addition, PDGF-D upregulated the mRNA expression of diverse growth factors such as vascular endothelial growth factor A, fibroblast growth factor 1 (FGF1), FGF5, leukemia inhibitory factor, inhibin, beta A, interleukin 11, and heparin-binding EGF-like growth factor. Therefore, the preconditioning of PDGF-D enhanced the hair-regenerative potential of ASCs. PDGF-D-induced growth factor expression was attenuated by a pharmacological inhibitor of mitogen-activated protein kinase pathway. In summary, PDGF-D is highly expressed by ASCs, where it acts as a potent mitogenic factor. PDGF-D also upregulates growth factor expression in ASCs. Therefore, PDGF-D can be considered a novel ASC stimulator, and used as a preconditioning agent before ASC transplantation.

Alveolar macrophages are critical for the inhibition of allergic asthma by mesenchymal stromal cells.

Multipotent mesenchymal stromal cells (MSCs) possess reparative and immunoregulatory properties, making them attractive candidates for cellular therapy. However, the majority of MSCs administered i.v. encounter a pulmonary impasse and soon disappear from the lungs, raising the question of how they induce such durable immunosuppressive effects. Using a mouse model of allergic asthma, we show that administration of MSCs isolated from human bone marrow, umbilical cord, or adipose tissue provoked a pronounced increase in alveolar macrophages and inhibited hallmark features of asthma, including airway hyperresponsiveness, eosinophilic accumulation, and Th2 cytokine production. Importantly, selective depletion of this macrophage compartment reversed the therapeutic benefit of MSC treatment on airway hyperresponsiveness. Our data demonstrate that human MSCs exert cross-species immunosuppressive activity, which is mediated by alveolar macrophages in allergic asthma. As alveolar macrophages are the predominant immune effector cells at the air-tissue interface in the lungs, this study provides a compelling mechanism for durable MSC effects in the absence of sustained engraftment.

Platelet-derived growth factor C and calpain-3 are modulators of human melanoma cell invasiveness.

The molecular mechanisms responsible for the elevated metastatic potential of malignant melanoma are still not fully understood. In order to shed light on the molecules involved in the acquisition by melanoma of a highly aggressive phenotype, we compared the gene expression profiles of two cell clones derived from the human cutaneous metastatic melanoma cell line M14: a highly invasive clone (M14C2/MK18) and a clone (M14C2/C4) with low ability to invade the extracellular matrix (ECM). The highly invasive phenotype of M14C2/MK18 cells was correlated with overexpression of neuropilin-1, activation of a vascular endothelial growth factor (VEGF)-A/VEGFR-2 autocrine loop and secretion of matrix metalloprotease-2. Moreover, in an in vivo murine model, M14C2/MK18 cells displayed a higher growth rate as compared with M14C2/C4 cells, even though in vitro both clones possessed comparable proliferative potential. Microarray analysis in M14C2/MK18 cells showed a strong upregulation of platelet-derived growth factor (PDGF)-C, a cytokine that contributes to angiogenesis, and downregulation of calpain-3, a calcium-dependent thiol-protease that regulates specific signalling cascade components. Inhibition of PDGF-C with a specific antibody resulted in a significant decrease in ECM invasion by M14C2/MK18 cells, confirming the involvement of PDGF-C in melanoma cell invasiveness. Moreover, the PDGF-C transcript was found to be upregulated in a high percentage of human melanoma cell lines (17/20), whereas only low PDGF-C levels were detected in a few melanocytic cultures (2/6). By contrast, inhibition of calpain-3 activity in M14C2/C4 control cells, using a specific chemical inhibitor, markedly increased ECM invasion, strongly suggesting that downregulation of calpain-3 plays a role in the acquisition of a highly invasive phenotype. The results indicate that PDGF-C upregulation and calpain-3 downregulation are involved in the aggressiveness of malignant melanoma and suggest that modulators of these proteins or their downstream effectors may synergise with VEGF­A therapies in combating tumour-associated angiogenesis and melanoma spread.

Impaired function of CTLA-4 in the lungs of patients with chronic beryllium disease contributes to persistent inflammation.

Chronic beryllium disease (CBD) is an occupational lung disorder characterized by granulomatous inflammation and the accumulation of beryllium-responsive CD4(+) T cells in the lung. These differentiated effector memory T cells secrete IL-2, IFN-γ, and TNF-α upon in vitro activation. Beryllium-responsive CD4(+) T cells in the lung are CD28 independent and have increased expression of the coinhibitory receptor, programmed death 1, resulting in Ag-specific T cells that proliferate poorly yet retain the ability to express Th1-type cytokines. To further investigate the role of coinhibitory receptors in the beryllium-induced immune response, we examined the expression of CTLA-4 in blood and bronchoalveolar lavage cells from subjects with CBD. CTLA-4 expression was elevated on CD4(+) T cells from the lungs of study subjects compared with blood. Furthermore, CTLA-4 expression was greatest in the beryllium-responsive subset of CD4(+) T cells that retained the ability to proliferate and express IL-2. Functional assays show that the induction of CTLA-4 signaling in blood cells inhibited beryllium-induced T cell proliferation while having no effect on the proliferative capacity of beryllium-responsive CD4(+) T cells in the lung. Collectively, our findings suggest a dysfunctional CTLA-4 pathway in the lung and its potential contribution to the persistent inflammatory response that characterizes CBD.

Spatial and temporal transcriptomics of Schistosoma japonicum-induced hepatic granuloma formation reveals novel roles for neutrophils.

The severity of schistosome egg-induced hepatic granulomatous pathology depends markedly on the nature of the host immune responses. In this study, we used LMM and microarray analysis to compare gene expression profiles of histologically distinct zones within, and directly proximal to, hepatic granulomas that developed in C57BL/6 mice infected with Schistosoma japonicum. There was significant up-regulation of type-1, type-2, and type-17 immune-associated genes within the granuloma core (adjacent to eggs), followed by increased expression of type-2 and fibrotic genes at the outer zones of granulomas. Neutrophil-associated genes were also found to be expressed differentially in the core and at the peripheral zone of granulomas, present at 7 weeks p.i., demonstrating a significant role of neutrophils in S. japonicum granulomatous pathology. The release of NETs was observed microscopically in granulomas obtained from the livers of infected mice and when human neutrophils were incubated in vitro in the presence of S. japonicum eggs. These finding are the first to suggest a novel, dual role for neutrophils in the mediation of tissue damage and repair in S. japonicum egg-induced hepatic granulomatous lesions. Together, these results provide an overview of the local events occurring within the granuloma microenvironment.

New proteoliposome vaccine formulation from N. meningitidis serogroup B, without aluminum hydroxide, retains its antimeningococcal protectogenic potential as well as Th-1 adjuvant capacity.

Proteoliposomes purified from the Outer Membrane of Neisseria meningitidis B, have been successfully used as core for adjuvants and vaccine formulations. We have tried to increase their structural definition and to conserve their efficacy and stability avoiding the addition of the aluminum hydroxide to the final formulation. Liposomal particle systems were prepared from components of defined molecular structure, such as a Neisseria meningitidis B protein complex, extracted and purified without forming vesicle structures. Liposomes were prepared from a mixture of dioleoyl phosphatidyl serine and cholesterol, using the classical dehydration-rehydration method. Transmission Electron Microscopy (TEM) was used to characterize the liposomes. BALB/c mice were used for animal testing procedures. Analysis of specific IgG response, serum bactericidal activity as well as DTH reaction was carried out. Isolation and purification of mRNA and real-time PCR, was performed to determine the dominating Th lymphokine pattern. The new antimeningococcal formulation without aluminum hydroxide prepared with components of defined molecular structure assembled itself into Neoproteoliposomes (NPL) ranging from 50 to 70 nm in diameter. The extraction and purification of selected membrane proteins to provide the antigen for this new formulation (PD-Tp), as well as the NPL-formulation favors a Th1 response pattern, suggested by the higher percentages of DTH, increased expression of proinflamatory lymphokine mRNAs when administered by intramuscular and intranasal routes. It stimulates a systemic bactericidal antibody response against Neisseria meningitidis B and immunologic memory similar to the Cuban VA-MENGOC-BC vaccine, even at lower dosages and is less reactogenic at the injection site in comparison with the formulation with aluminum hydroxide. This new adjuvant formulation could be applicable to the development of new and improved vaccines against meningococcal disease, and eventually as modulators of the immune response against other diseases.

The role of B cells and humoral immunity in Mycobacterium tuberculosis infection.

Tuberculosis (TB) remains a serious threat to public health, causing 2 million deaths annually world-wide. The control of TB has been hindered by the requirement of long duration of treatment involving multiple chemotherapeutic agents, the increased susceptibility to Mycobacterium tuberculosis infection in the HIV-infected population, and the development of multi-drug resistant and extensively resistant strains of tubercle bacilli. An efficacious and cost-efficient way to control TB is the development of effective anti-TB vaccines. This measure requires thorough understanding of the immune response to M. tuberculosis. While the role of cell-mediated immunity in the development of protective immune response to the tubercle bacillus has been well established, the role of B cells in this process is not clearly understood. Emerging evidence suggests that B cells and humoral immunity can modulate the immune response to various intracellular pathogens, including M. tuberculosis. These lymphocytes form conspicuous aggregates in the lungs of tuberculous humans, non-human primates, and mice, which display features of germinal center B cells. In murine TB, it has been shown that B cells can regulate the level of granulomatous reaction, cytokine production, and the T cell response. This chapter discusses the potential mechanisms by which specific functions of B cells and humoral immunity can shape the immune response to intracellular pathogens in general, and to M. tuberculosis in particular. Knowledge of the B cell-mediated immune response to M. tuberculosis may lead to the design of novel strategies, including the development of effective vaccines, to better control TB.

CD70 deficiency impairs effector CD8 T cell generation and viral clearance but is dispensable for the recall response to lymphocytic choriomeningitis virus.

CD27 interactions with its ligand, CD70, are thought to be necessary for optimal primary and memory adaptive immune responses to a variety of pathogens. Thus far, all studies addressing the function of the CD27-CD70 axis have been performed in mice lacking CD27, in those overexpressing CD70, or in those in which these molecules were blocked or mimicked by Abs or recombinant soluble CD70. Because these methods have in some cases led to divergent results, we generated CD70-deficient mice to directly assess its role in vivo. We find that lack of CD70-mediated stimulation during primary responses to lymphocytic choriomeningitis virus lowered the magnitude of CD8 Ag-specific T cell response, resulting in impaired viral clearance, without affecting CD4 T cell responses. Unexpectedly, CD70-CD27 costimulation was not needed for memory CD8 T cell generation or the ability to mount a recall response to lymphocytic choriomeningitis virus. Adoptive transfers of wild-type memory T cells into CD70(-/-) or wild-type hosts also showed no need for CD70-mediated stimulation during the course of the recall response. Moreover, CD70 expression by CD8 T cells could not rescue endogenous CD70(-/-) cells from defective expansion, arguing against a role for CD70-mediated T:T help in this model. Therefore, CD70 appears to be an important factor in the initiation of a robust and effective primary response but dispensable for CD8 T cell memory responses.

Cediranib inhibits both the intraosseous growth of PDGF D-positive prostate cancer cells and the associated bone reaction.

BACKGROUND: The major cause of death in prostate cancer (PCa) cases is due to distant metastatic lesions, with the bone being the most prevalent site for secondary colonization. Utilization of small molecule inhibitors to treat bone metastatic PCa have had limited success either as monotherapies or in combination with other chemotherapeutics due to intolerable toxicities. In the current study, we developed a clinically relevant in vivo intraosseous tumor model overexpressing the platelet-derived growth factor D (PDGF D) to test the efficacy of a newly characterized vascular endothelial growth factor receptor (VEGFR)/PDGFR inhibitor, cediranib (also called AZD2171). METHODS: An intratibial-injection model was established utilizing DU145 cells with or without increased PDGF D expression. Tumor-bearing mice were treated by daily gavage administration of cediranib and/or weekly i.p. injection of docetaxel for 7 weeks. Tibiae were monitored by in vivo/ex vivo X-rays and histomorphometry analysis was performed to estimate tumor volume and tumor-associated trabecular bone growth. RESULTS: Cediranib reduced intraosseous growth of prostate tumors as well as tumor-associated bone responses. When compared to the standard chemotherapeutic agent docetaxel, cediranib exhibited a stronger inhibition of tumor-associated bone response. The efficacy of cediranib was further enhanced when the drug was co-administered with docetaxel. Importantly, the therapeutic benefits of cediranib and docetaxel are more prominent in intraosseous prostate tumors overexpressing PDGF D. CONCLUSION: These novel findings support the utilization of cediranib, either alone or in combination with docetaxel, to treat bone metastatic PCa exhibiting PDGF D expression.

The impact of aging on cancer vaccination.

Cancer vaccination is less effective at old than at young age, due to T cell unresponsiveness, caused by various age-related changes of the immune system. This includes lack of naïve T cells, defects in activation pathways of T cells and antigen-presenting cells (APC), and age-related changes in the tumor microenvironment. Although evidence exists that also natural killer (NK) and natural killer T (NKT) cells of the innate immune system change with age, comparison of various studies involving adaptive and innate immune responses in elderly and cancer patients, as well as cancer vaccination at young and old age in this review, indicates that also innate immune responses should be tested as a potential candidate to improve immunotherapy against cancer at older age.

Naturally occurring IgM anti-leukocyte autoantibodies inhibit T-cell activation and chemotaxis.

INTRODUCTION: Naturally occurring IgM antileukocyte autoantibodies (IgM-ALA) are present from birth and increase during inflammatory processes of diverse etiologies. The clinical observation demonstrating a significant correlation (P < 01) between lack of acute rejections and presence of high levels of IgM-ALA in recipients of kidney allografts prompted us to study if IgM-ALA alters T-cell function and leukocyte chemotaxis. METHODS: In-vitro functional assays were performed using leucocytes isolated from human peripheral blood. In-vivo studies were performed in C57BL6 mice. RESULT: Human studies revealed that IgM-ALA consist of several different IgM, each with specificities for a different leukocyte receptor, e.g., CD3, CD4, CCR5, and CXCR4. We show that IgM inhibits T-cell activation, proliferation, and chemotaxis. Data on in vivo murine models of ischemia-reperfusion injury and cardiac transplantation support our hypothesis. CONCLUSION: The innate anti-inflammatory mechanism of IgM-ALA can be exploited by using purified normal IgM to inhibit inflammatory states or by a vaccine approach to increase in vivo production of IgM-ALA (e.g., prior to a transplant).

Involvement of CD91 and scavenger receptors in Hsp70-facilitated activation of human antigen-specific CD4+ memory T cells.

Hsp70 plays several roles in the adaptive immune response. Based on the ability to interact with diverse peptides, extracellular Hsp70:peptide complexes exert profound effects both in autoimmunity and in tumor rejection by evoking potent T cell responses to the chaperoned peptide. The interaction with receptors on APC represents the basis for the immunological functions of Hsp70 and a critical point where the immune response can be regulated. Various surface proteins (e.g. CD91, scavenger receptors (SR)) have been implicated in binding of Hsp70. In this study, antigenic peptides from tetanus toxin and influenza hemagglutinin complexed to human stress-inducible Hsp70 were found to enhance the proliferation and cytokine production of human antigen-specific CD4(+) T cells. This was demonstrated in proliferation experiments using human monocytes as APC. Proliferated antigen-specific cells were detected combining HLA-DRB1*0401 or HLA-DRB1*1101 tetramer and CFSE staining. Treating monocytes with CD91 siRNA diminished these effects. Additional blocking of SR by the SR ligand fucoidan completely abolished enhanced proliferation and production of Th1 and Th2 cytokines. Taken together, our data indicate that in the human system, CD91 and members of the SR family efficiently direct Hsp70:peptide complexes into the MHC class II presentation pathway and thus enhance antigen-specific CD4(+) T cell responses.

Inverse correlation between PDGFC expression and lymphocyte infiltration in human papillary thyroid carcinomas.

BACKGROUND: Members of the PDGF family have been suggested as potential biomarkers for papillary thyroid carcinomas (PTC). However, it is known that both expression and stimulatory effect of PDGF ligands can be affected by inflammatory cytokines. We have performed a microarray study in a collection of PTCs, of which about half the biopsies contained tumour-infiltrating lymphocytes or thyroiditis. To investigate the expression level of PDGF ligands and receptors in PTC we measured the relative mRNA expression of all members of the PDGF family by qRT-PCR in 10 classical PTC, eight clinically aggressive PTC, and five non-neoplastic thyroid specimens, and integrated qRT-PCR data with microarray data to enable us to link PDGF-associated gene expression profiles into networks based on recognized interactions. Finally, we investigated potential influence on PDGF mRNA levels by the presence of tumour-infiltrating lymphocytes. METHODS: qRT-PCR was performed on PDGFA, PDGFB, PDGFC, PDGFD, PDGFRA PDGFRB and a selection of lymphocyte specific mRNA transcripts. Semiquantitative assessment of tumour-infiltrating lymphocytes was performed on the adjacent part of the biopsy used for RNA extraction for all biopsies, while direct quantitation by qRT-PCR of lymphocyte-specific mRNA transcripts were performed on RNA also subjected to expression analysis. Relative expression values of PDGF family members were combined with a cDNA microarray dataset and analyzed based on clinical findings and PDGF expression patterns. Ingenuity Pathway Analysis (IPA) was used to elucidate potential molecular interactions and networks. RESULTS: PDGF family members were differentially regulated at the mRNA level in PTC as compared to normal thyroid specimens. Expression of PDGFA (p = 0.003), PDGFB (p = 0.01) and PDGFC (p = 0.006) were significantly up-regulated in PTCs compared to non-neoplastic thyroid tissue. In addition, expression of PDGFC was significantly up-regulated in classical PTCs as compared to clinically aggressive PTCs (p = 0.006), and PDGFRB were significantly up-regulated in clinically aggressive PTCs (p = 0.01) as compared to non-neoplastic tissue. Semiquantitative assessment of lymphocytes correlated well with quantitation of lymphocyte-specific gene expression. Further more, by combining TaqMan and microarray data we found a strong inverse correlation between PDGFC expression and the expression of lymphocyte specific mRNAs. CONCLUSION: At the mRNA level, several members of the PDGF family are differentially expressed in PTCs as compared to normal thyroid tissue. Of these, only the PDGFC mRNA expression level initially seemed to distinguish classical PTCs from the more aggressive PTCs. However, further investigation showed that PDGFC expression level correlated inversely to the expression of several lymphocyte specific genes, and to the presence of lymphocytes in the biopsies. Thus, we find that PDGFC mRNA expression were down-regulated in biopsies containing infiltrated lymphocytes or thyroiditis. No other PDGF family member could be linked to lymphocyte specific gene expression in our collection of PTCs biopsies.

miR-200 regulates PDGF-D-mediated epithelial-mesenchymal transition, adhesion, and invasion of prostate cancer cells.

MicroRNAs have been implicated in tumor progression. Recent studies have shown that the miR-200 family regulates epithelial-mesenchymal transition (EMT) by targeting zinc-finger E-box binding homeobox 1 (ZEB1) and ZEB2. Emerging evidence from our laboratory and others suggests that the processes of EMT can be triggered by various growth factors, such as transforming growth factor beta and platelet-derived growth factor-D (PDGF-D). Moreover, we recently reported that overexpression of PDGF-D in prostate cancer cells (PC3 PDGF-D cells) leads to the acquisition of the EMT phenotype, and this model offers an opportunity for investigating the molecular interplay between PDGF-D signaling and EMT. Here, we report, for the first time, significant downregulation of the miR-200 family in PC3 PDGF-D cells as well as in PC3 cells exposed to purified active PDGF-D protein, resulting in the upregulation of ZEB1, ZEB2, and Snail2 expression. Interestingly, re-expression of miR-200b in PC3 PDGF-D cells led to reversal of the EMT phenotype, which was associated with the downregulation of ZEB1, ZEB2, and Snail2 expression, and these results were consistent with greater expression levels of epithelial markers. Moreover, transfection of PC3 PDGF-D cells with miR-200b inhibited cell migration and invasion, with concomitant repression of cell adhesion to the culture surface and cell detachment. From these results, we conclude that PDGF-D-induced acquisition of the EMT phenotype in PC3 cells is, in part, a result of repression of miR-200 and that any novel strategy by which miR-200 could be upregulated would become a promising approach for the treatment of invasive prostate cancer.

Paracrine signaling by platelet-derived growth factor-CC promotes tumor growth by recruitment of cancer-associated fibroblasts.

Cancer results from the concerted performance of malignant cells and stromal cells. Cell types populating the microenvironment are enlisted by the tumor to secrete a host of growth-promoting cues, thus upholding tumor initiation and progression. Platelet-derived growth factors (PDGF) support the formation of a prominent tumor stromal compartment by as of yet unidentified molecular effectors. Whereas PDGF-CC induces fibroblast reactivity and fibrosis in a range of tissues, little is known about the function of PDGF-CC in shaping the tumor-stroma interplay. Herein, we present evidence for a paracrine signaling network involving PDGF-CC and PDGF receptor-alpha in malignant melanoma. Expression of PDGFC in a mouse model accelerated tumor growth through recruitment and activation of different subsets of cancer-associated fibroblasts. In seeking the molecular identity of the supporting factors provided by cancer-associated fibroblasts, we made use of antibody arrays and an in vivo coinjection model to identify osteopontin as the effector of the augmented tumor growth induced by PDGF-CC. In conclusion, we establish paracrine signaling by PDGF-CC as a potential drug target to reduce stromal support in malignant melanoma.