Littérature scientifique sur le sujet « MDSC, pancreatic ductal adenocarcinoma, humanized mice »

BackgroundPancreatic Ductal Adenocarcinoma (PDAC) has very poor 5-year overall survival rate. Despite the encouraging effect of immunotherapy in other cancer types, clinical benefit in PDAC patients remains limited. One of the reasons for the lack of success is the immunosuppressive tumor microenvironment (TME), which is maintained by myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages. High MDSC infiltration is associated with a poor survival in PDAC patients. Our project aims at identifying tumor-driven chemokines that influence recruitment of MDSC and establishment of the immunosuppressive tumor microenvironment.Materials and Methods45 PDAC cell lines generated from spontaneous tumors of genetically-modified mice harboring the characteristic driver mutations KrasG12D or PIK3CAH1047R were analyzed for their expression levels of CXCL1, CCL2, G-CSF and GM-CSF by qRT-PCR. In order to study the relationship between the chemokine/cytokine profile and the immune cell infiltration, selected tumor cell lines were implanted orthotopically in C57BL6 mice. Three weeks after inoculation blood, spleen and tumor were isolated and organ specific immune cell infiltration was analyzed by flow cytometry. To further characterize tumor-secreted factors tumor conditioned medium was generated and the concentration of 33 chemokines was analyzed in a multiplex assay. The chemokine levels were correlated with migratory capacity of splenic MDSC measured in an ex vivo chemotaxis assay.ResultsCXCL1 significantly enhanced migration of polymorphonuclear MDSC (PMN-MDSC) in vitro, while migration of monocytic MDSC (M-MDSC) was predominantly skewed towards CCL2. Three weeks after tumor inoculation, MDSC populations in blood and spleen were expanded. Most intriguingly, PDAC cell lines with high CXCL1 or CCL2 levels in vitro showed significantly enriched intratumoral accumulation of PMN-MDSC and M-MDSC, respectively, suggesting that tumor-intrinsic chemokine secretion and not factors from the tumor stroma determined MDSC infiltration. The ex vivo chemotaxis assays revealed additional factors that modulate migration of MDSC into the TME.ConclusionsThe in vitro gene expression levels of individual chemokines (CXCL1 and CCL2) determines the MDSC infiltration in vivo into the TME. Targeting the chemokine-receptor axis of MDSC subpopulations could be a promising approach in the treatment of pancreatic cancer.FundingThe project was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer 329628492 - SFB 1321 and the Förderprogramm für Forschung und Lehre (FöFoLe) funded by the Ludwig-Maximilians-Universität München.Disclosure InformationC. Rambuscheck: None. P. Metzger: None. C. Hörth: None. R. Hennel: None. S. Bärthel: None. C. Falcomatà: None. K. Lauber: None. S. Endres: None. D. Saur: None. M. Schnurr: None. L.M. König: None.

e16744 Background: Carcinoembryonic cell adhesion molecule 6 (CEACAM6) is a cell adhesion receptor of the Ig-superfamily overexpressed in human Pancreatic Ductal Adenocarcinoma (PDA), enriching to the classical activated stroma subtype. CEACAM6 has multifaceted roles in PDA and is a poor prognostic maker (Pandey et al. Sci Rep 2019). We report functional correlative studies across PDA cell lines with high vs KO vs low of CEACAM6 and a PDX model with a therapeutic Mab. Methods: RNA-Seq and microarray expression data of PDA cell lines were downloaded from GEO using R (4.3), normalized and log transformed for analysis: CEACAM6 high vs. low were assessed for differential gene expression changes. Correlation of CEACAM6 levels with genes of interest was studied and compared with the CEACAM6 KO proteomic profile of HPAF-II cells. CEACAM6 WT vs. KO cells were profiled for protein kinase (PK) activity (PAMChip) and gene expression changes by RNA-Seq. NSG-CD34+ mice bearing PDX were evaluated with a humanized anti-CEACAM6 Mab for anti-tumor activity. Results: Differential expression analyses between PDA cell lines with low vs KO vs high CEACAM6 resulted in identifying similar markers changing in quantitative proteomics. KRT20, SYTL1, SKIL, CES1P1, MAN1A1 were down-regulated and HMOX1, CPNE2, ABCD1 were up-regulated in CEACAM6 low or KO cell lines. Specific PKs are upregulated in CEACAM6 KO enriching to the TK family (EPH A1, 3, 4, 8 and HCK), AGC family (e.g. AKT, PKA) and cellular apoptosis (e.g. BAD). RNA-Seq of CEACAM6 WT vs KO cells reconfirmed the up-regulation of MMP1, IL2RG, ATP6V0D2 and low expression of KRT20, AGK and MAN1A1 in CEACAM6 KO cells. Pharmacologic inhibition with a humanized anti-CEACAM6 scFv-Fc (IgG4) in PDA PDX of NSG CD34+ mice demonstrated ~55% tumor growth inhibition (TGI) with enhanced survival of > 14 days vs. control. Conclusions: CEACAM6 is expressed exclusively in primates and humans and plays multifaceted oncogenic roles in PDA pathogenesis. When CEACAM6 is disrupted, ECM proteins are altered reshaping the stroma, activating specific PKs and priming apoptosis. The therapeutic anti-CEACAM6 Mab possesses anti-tumor activity with associated cellular apoptosis and increased mouse survival.

Abstract Pancreatic ductal adenocarcinoma is characterized by a strong immunosuppressive network with a dense infiltration of myeloid cells including myeloid-derived suppressor cells (MDSC). Two distinct populations of MDSC have been defined: polymorphonuclear MDSC (PMN-MDSC) and monocytic MDSC (M-MDSC). Several factors influence the development and function of MDSC including the transcription factor interferon regulatory factor 4 (IRF4). Here, we show that IRF4 deficiency accelerates tumor growth and reduces survival, accompanied with a dense tumor infiltration with PMN-MDSC and reduced numbers of CD8+ T cells. As IRF4 has been described to modulate myeloid cell development and function, particularly of PMN-MDSC, we analyzed its role using MDSC-specific IRF4 knockout mice with the Ly6G or LysM knock-in allele expressing Cre recombinase and Irf4flox. In GM-CSF-driven bone marrow cultures, IRF4 deficiency increased the frequency of MDSC-like cells with a strong T cell suppressive capacity. Myeloid (LysM)-specific depletion of IRF4 led to increased tumor weight and a moderate splenic M-MDSC expansion in tumor-bearing mice. PMN cell (Ly6G)-specific depletion of IRF4, however, did not influence tumor progression or MDSC accumulation in vivo in accordance with our finding that IRF4 is not expressed in PMN-MDSC. This study demonstrates a critical role of IRF4 in the generation of an immunosuppressive tumor microenvironment in pancreatic cancer, which is independent of IRF4 expression in PMN-MDSC.

BackgroundA significant challenge to overcome in pancreatic ductal adenocarcinoma (PDAC) is the profound systemic immunosuppression that renders this disease non-responsive to immunotherapy. Our supporting data provide evidence that CD200, a regulator of myeloid cell activity, is expressed in the PDAC microenvironment. Additionally, myeloid-derived suppressor cells (MDSC) isolated from patients with PDAC express elevated levels of the CD200 receptor (CD200R). Thus, we hypothesize that CD200 expression in the PDAC microenvironment limits responses to immunotherapy by promoting expansion and activity of MDSC.MethodsImmunofluorescent staining was used to determine expression of CD200 in murine and human PDAC tissue. Flow cytometry was utilized to test for CD200R expression by immune populations in patient blood samples. In vivo antibody blocking of CD200 was conducted in subcutaneous MT-5 tumor-bearing mice and in a genetically engineered PDAC model (KPC-Brca2 mice). Peripheral blood mononuclear cells (PBMC) from patients with PDAC were analyzed by single-cell RNA sequencing. MDSC expansion assays were completed using healthy donor PBMC stimulated with IL-6/GM-CSF in the presence of recombinant CD200 protein.ResultsWe found expression of CD200 by human pancreatic cell lines (BxPC3, MiaPaca2, and PANC-1) as well as on primary epithelial pancreatic tumor cells and smooth muscle actin+ stromal cells. CD200R expression was found to be elevated on CD11b+CD33+HLA-DRlo/− MDSC immune populations from patients with PDAC (p=0.0106). Higher expression levels of CD200R were observed in CD15+ MDSC compared with CD14+ MDSC (p<0.001). In vivo studies demonstrated that CD200 antibody blockade limited tumor progression in MT-5 subcutaneous tumor-bearing and in KPC-Brca2 mice (p<0.05). The percentage of intratumoral MDSC was significantly reduced in anti-CD200 treated mice compared with controls. Additionally, in vivo blockade of CD200 can also significantly enhance the efficacy of PD-1 checkpoint antibodies compared with single antibody therapies (p<0.05). Single-cell RNA sequencing of PBMC from patients revealed that CD200R+ MDSC expressed genes involved in cytokine signaling and MDSC expansion. Further, in vitro cytokine-driven expansion and the suppressive activity of human MDSC was enhanced when cocultured with recombinant CD200 protein.ConclusionsThese results indicate that CD200 expression in the PDAC microenvironment may regulate MDSC expansion and that targeting CD200 may enhance activity of checkpoint immunotherapy.

Abstract Pancreatic Ductal Adenocarcinoma (PDA) is a very aggressive tumor for which effective therapeutical strategies are still lacking. The global five-years survival is of 5% and surgery is the only potentially curative treatment. The PDA-associated antigen α-enolase (ENO1), beside its glycolytic function, acts as a plasminogen receptor, promoting activation into plasmin, involved in extracellular matrix degradation. Antibodies against ENO1 are detected in more than 60% of PDA patients and correlate with a better prognosis. Furthermore, anti-ENO1 antibodies are induced in mice after ENO1-DNA vaccination. We observed an increased ENO1 expression on the cell surface of both PDA and myeloid cells (MDSC), suggesting a role in tumor progression and spreading. The immunotherapy represents a chance to selectively target PDA cells and MDSC. Mouse anti-human ENO1 monoclonal antibody (mAb) inhibits plasminogen-dependent invasion of human PDA cells and metastatic spreading in immunosuppressed mice, as well as MDSC adhesion to pancreatic endothelial cells and in vitro and in vivo migration. Similarly MDSC arginase activity and secretion of IL-6 decrease after ENO1 triggering, while anti-ENO1 treatment does not affect costimulatory molecule expression and MDSC suppression functions. Notably, a single administration of Adeno-Associated Virus (AAV)-expressing an anti-ENO1 mAb reduced the number of lung metastases in immunosuppressed mice injected with PDA cells. In conclusion, the antibodies anti-ENO1 may inhibit PDA cell and myeloid cell invasion and modulate T cell response, making the immunotherapy more effective.

The portal venous circulation provides a conduit for pancreatic ductal adenocarcinoma (PDAC) tumor cells to the liver parenchyma sinusoids, a frequent site of metastasis. Turbulent flow in the portal circulation promotes retention of PDAC shed circulating tumor cells (CTC) and myeloid-derived immunosuppressor cells (MDSC). Excessive colony stimulating factor-1 receptor (CSF1R) signaling can induce myeloid differentiation to MDSC and transformation of MDSC to myeloid-derived fibroblasts (M-FB). Interactions between PDAC CTC and M-FB in the portal blood promotes the formation of immunoresistant clusters that enhance CTC proliferation, migration, and survival. Analysis of portal and peripheral blood samples collected intraoperatively from 30 PDAC patients undergoing pancreatico-duodenectomy showed that PDAC patient plasma contained high levels of macrophage colony stimulating factor (M-CSF/CSF1), granulocyte-macrophage colony stimulating factor (GM-CSF/CSF2), interleukin-8 (IL-8), and interleukin-34 (IL-34) compared to healthy control levels. Moreover, the level of M-CSF in portal blood was significantly higher than that detected in the peripheral blood of PDAC patients. PDAC CTC aseptically isolated by fluorescence activated cell sorting (FACS) out of freshly collected patient portal blood mononuclear cells (PortalBMC) had elevated RNA expression of IL34 (IL-34 gene) and CSF1 (M-CSF/CSF1 gene) which both signal through CSF1R. PDAC CTC also had high levels of RNA expression for CXCL8, the gene encoding chemokine interleukin-8 (IL-8) which can attract myeloid cells through their CXCR2 receptors. FACS-isolated portal PDAC CTC and M-FB co-cultured ex vivo had increased CTC proliferation, motility, and cluster formation compared to CTC cultured alone. CSF1R and CXCR2 cell surface expression were found on PDAC portal blood CTC and M-FB, suggesting that both cell types may respond to M-CSF, IL-34, and IL-8-mediated signaling. Portal PDAC CTC displayed enhanced RNA expression of CSF1 and IL34, while CTC+M-FB+ clusters formed in vivo had increased RNA expression of CSF2 and IL34. Portal M-FB were found to have high CSF1R RNA expression. CTC isolated from ex vivo 7-day cultures of PDAC patient portal blood mononuclear cells (PortalBMC) expressed elevated CSF1, IL34, and IL8 RNA, and CSF1 expression was elevated in M-FB. Treatment with rabbit anti-CSF1R antibodies decreased CTC proliferation. Treatment of PortalBMC cultures with humanized anti-CSF1R, humanized anti-IL-8, or anti-IL-34 antibodies disrupted CTC cluster formation and increased CTC apoptosis. U937 myeloid precursor cell line cultures treated with conditioned media from PortalBMC ex vivo cultures without treatment or treated with anti-IL-8 and/or anti-CSF1R did not prevent myeloid differentiation in the myeloid precursor cell line U937 to macrophage, dendritic cell, MDSC, and M-FB phenotypes; whereas, U937 cultures treated with conditioned media from PortalBMC ex vivo cultures exposed to anti-IL-34 were significantly inhibited in their myeloid differentiation to all but the M-FB phenotype. PDAC patient T cells that were found phenotypically anergic (CD3+CD25+CTLA4+PD1L1+) in PortalBMC could be re-activated (CD3+CD25+CTLA4-PD1L1-), and displayed increased interferon gamma (IFNγ) production when PortalBMC ex vivo cultures were treated with anti-CSF1R, anti-IL-8, and anti-IL-34 antibodies alone or in combination. These findings suggest that PDAC CTC have the potential to influence myeloid differentiation and/or antigen presenting cell activation in the PDAC portal blood microenvironment, and that disruption of CTC/M-FB interactions may be potential targets for reversing the immunosuppression supporting CTC survival in the portal blood.

Abstract Introduction: Abundance of myeloid-derived suppressor cells (MDSC) and a dysfunctional T-cell compartment are defining hallmarks of therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC). Using congenic in vivo murine models to phenocopy extremes of T-cell enrichment or exclusion, we sought to interrogate central MDSC-mediated mechanisms that govern immune tolerance in PDAC. Methods: Orthotopically implanted T-cell-excluded (Tcelllo) vs T-cell-enriched (T-cellhi) congenic KPC tumors, and intratumoral Ly6G+F4/80- MDSCs from both clones, were subjected to RNA sequencing. Ex vivo co-cultures evaluated the effects of intratumoral MDSC on splenic T-cells. Orthotopically injected KPC-T-celllo mice were treated with etanercept vs. vehicle, and immunophenotyping via flow cytometry was performed. Results: RNA-seq of KPC T-celllo vs. T-cellhi tumors revealed enrichment of myeloid immunoregulatory pathways, and downregulation of leukocyte activation/cytotoxicity pathways. Flow cytometry revealed a dramatic increase in MDSCs infiltrating KPC-Tcelllo tumors (P&lt;0.001). To decipher MDSC-intrinsic mechanisms associated with T-cell exclusion, RNA-seq of MDSCs infiltrating T-cellhi clones revealed relative downregulation of MAPK signaling, and cytokine profiling of MDSCs conditioned with MAPK inhibitor trametinib revealed marked reduction in TNF secretion. Confocal microscopy confirmed striking decrease in TNF in MDSCs isolated from KPC- T-cellhi vs. Tcelllo tumors. Ex vivo MDSC-T-cell co-cultures significantly attenuated T-cell proliferation and activation (via IFN-γ release) while favoring T-cell apoptosis, which could be rescued by pre-conditioning MDSCs with either etanercept (TNFR2 decoy receptor) or MAPK pathway inhibitors. Orthotopically injected KPC-T-celllo tumor-bearing mice treated with etanercept demonstrated a remodeled TME vs. vehicle-treated mice, with attenuation in MDSC trafficking, enrichment in CD4+/CD8+ T-cell infiltration, and reduction in T-cell exhaustion. Conclusion: MDSC-derived TNF regulates T-cell dysfunction in PDAC via a MAPK-dependent mechanism. Compartment-specific inhibition of TNF may be a provocative strategy to overcome immune tolerance in PDAC. Citation Format: Anna Bianchi, Iago De Castro Silva, Nilesh U. Deshpande, Siddharth Mehra, Samara Singh, Austin R. Dosch, Vanessa T. Garrido, Christine I. Rafie, Nagaraj Nagathihalli, Nipun Merchant, Jashodeep Datta. MDSC-derived TNF is a novel regulator of T-cell dysfunction in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2513.

Abstract Activation of cellular signaling pathways by crosstalk between tumor cells and their microenvironment is an essential mechanism supporting pancreatic carcinogenesis. In this study, we aim to disrupt cellular signaling pathways by targeting ADAM17 (a disintegrin and metalloprotease 17). ADAM17 is a membrane bound enzyme which cleaves cell surface proteins. Its function is closely linked with autocrine and paracrine signaling of immunomodulation as well as activation of EGFR, which is a central molecule for pancreatic tumorigenesis. To investigate whether EGFR is activated via a paracrine manner from macrophages, the most abundant immune-related stromal cells in pancreas cancers, we generated a pancreatic tumor mouse model with ADAM17 deletion in myeloid cells by using a dual recombinase strategy. We observed that lack of ADAM17 in the myeloid cells resulted in a delay of acinar cell transformation and an associated decrease in EGFR activation. To further examine the tumor supportive role of ADAM17, systemic inhibition of ADAM17 using anti-ADAM17 antibody, MEDI3622, was tested in orthotopic tumor bearing mice. Systemic blockade of ADAM17 significantly reduced tumor burden and suppressed activation of EGFR and STAT3, which are associated with two pro-tumoral signaling pathways. In addition, we found an elevated level of CCL21 in the MEDI3622-treated tumors resulting in increased tumor infiltration by dendritic cells and cytotoxic T cells as well as low infiltration of G-MDSC (granulocytic myeloid-derived suppressor cells). These results demonstrate a pronounced anti-tumor effect by ADAM17 blockade and indicate ADAM17 as a therapeutic target of pancreatic cancer. Citation Format: Hui-Ju Wen, Jacee Moore, Erick Davis, Daniel Long, Justin Lee, Brian Devorkin, Howard Crawford. Disruption of ADAM17-dependent cellular crosstalk inhibits tumor progression of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B080.

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and will become the 2nd leading cause of cancer related death in the United States within the next 10 years. Lack of early symptoms and a poor response to current therapies make PDAC the deadliest of all major cancers. PDAC is characterized by a dense fibroinflammatory stroma which is composed of fibroblasts and immune cells and has been implicated to influence tumor progression and therapeutic outcome. In this study, we aim to disrupt cellular signaling pathways by targeting ADAM17 (a disintegrin and metalloprotease 17). ADAM17 is a membrane bound enzyme which cleaves cell surface proteins. Its function is closely linked with autocrine and paracrine signaling of immunomodulation as well as activation of EGFR, which is a central molecule for pancreatic tumorigenesis. To investigate whether EGFR is activated via a paracrine manner from macrophages, the most abundant immune-related stromal cells in pancreas cancers, we generated a pancreatic tumor mouse model with ADAM17 deletion in myeloid cells by using a dual recombinase strategy. We observed that lack of ADAM17 in the myeloid cells resulted in a delay of acinar cell transformation and an associated decrease in EGFR activation. To further examine the tumor supportive role of ADAM17, systemic inhibition of ADAM17 using anti-ADAM17 antibody, MEDI3622, was tested in orthotopic tumor bearing mice. Tumor regression was observed in the mice treated with MEDI3622 and was accompanied by high infiltration of cytotoxic T cells and low infiltration of G-MDSC (granulocytic myeloid-derived suppressor cells). In addition, activation of EGFR and STAT3, which are associated with two pro-tumoral signaling pathways, were reduced by MEDI3622. These results demonstrate a pronounced anti-tumor effect by ADAM17 blockage and indicate ADAM17 as a therapeutic target of pancreatic cancer. Citation Format: Hui-Ju Wen, Howard Crawford. Disruption of cellular crosstalk by blockage of ADAM17 inhibits tumor progression of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 341.

Abstract Pancreatic cancer (PDAC) remains one of the most lethal malignancies due to its late diagnosis and poor response to treatment. Preclinical models reflecting the uniquely complex structure of PDAC cells and the surrounding tumor microenvironment (TME) are required to ensure translational results. PDAC organoids, ex vivo 3D models of primary tumor cells, form an exciting preclinical model that reflects the complexity of PDAC. Tumor organoids co-cultured with stromal and immune cells have been previously explored in vitro but have thus far remained limited in any in vivo capacity. We therefore aimed to establish and characterize in vitro co-cultured PDAC organoids using primary human PDAC tumor samples plus autologous peripheral or splenic lymphocytes. Subsequent preliminary in vivo models have been established by engrafting co-cultured PDAC organoids and PDAC cancer associated fibroblasts into immunocompromised mice. The pilot data assessed retention, growth kinetics and metastatic potential and will subsequently form the foundation for comparable experiments using autologous humanized mouse models. This humanized mouse model, consisting of autologous human malignant, stromal and immune compartments, will add to the existing repertoire of preclinical models by more closely representing the entire tumor volume. In vitro and in vivo data compared to other preclinical models. Additional preliminary therapeutic response data may provide translational value and warrant further evaluation. Citation Format: Alexander J. P. Fulton, Kourosh Saeb-Parsy, Bristi Basu. Developing a novel in vivo model of pancreatic ductal adenocarcinoma using primary tumor samples and humanised mouse models [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A074.

In diversi tipi di tumore sia nell’uomo che in modelli murini, fattori prodotti dal tumore sostengono l'accumulazione e il differenziamento funzionale di cellule mieloidi, incluse le cellule soppressorie di derivazione mieloide (MDSC), che possono interferire con le risposte mediata delle cellule T. Lo scopo di questo studio è stato quello di caratterizzare la presenza di MDSC nel sangue di pazienti con adenocarcinoma del dotto pancreatico (PDAC) e valutare il loro ruolo come biomarcatori. I nostri risultati mostrano che le MDSC monocitiche (MO-MDSC) sono significativamente espanse nei pazienti PDAC rispetto ai controlli sani. All'interno dei donatori PDAC, alcuni presentano monociti con capacità immunosoppressoria verso le cellule T e questo fenotipo è accompagnato da un profilo di espressione genica specifico e diverso da quello dei monociti non soppressori isolati da altri pazienti PDAC o dai controlli sani. Le nostre osservazioni suggeriscono che esiste uno specifico “codice a barre” genetico che identifica le MO-MDSC soppressorie nei pazienti PDAC e questo strumento può potenzialmente essere utilizzato come fattore prognostico, nonché come importante informazione aggiuntiva utile per stabilire la necessità di un trattamento o co-trattamento immunologico nella cura del cancro al pancreas. L’interazione dinamica tra il cancro e il sistema immunitario umano può essere studiata in vivo nei topi ripopolati con le cellule ematopoietiche umane (topi HIR). Qui si descrive uno strumento per sostenere la mielopoiesi umana in questi modelli mediante l’approvvigionamento di citochine umane attraverso vettori adenovirali. Il modello così modificato è stato impiegato per lo studio del cancro al pancreas. Abbiamo dimostrato che la presenza del sistema immunitario umano favorisce la progressione del tumore, infatti, la frequenza di micrometastasi polmonari è significativamente più alta nei topi HIR con tumore rispetto ai topi controlli. I leucociti umani che popolano la nicchia pre-metastatica sono caratterizzati da un profilo genetico fortemente legato al compartimento mieloide e all’infiammazione. Tra i fattori più espressi in presenza di tumore troviamo la proteina S100B, il cui livello sierico è significativamente diverso nei pazienti PDAC rispetto ai controlli ed ai pazienti con pancreatite cronica. Questo studio apre nuove possibilità per la caratterizzazione di un "codice a barre" genetico utile per identificare MO-MDSC soppressorie nei pazienti con adenocarcinoma pancreatico. Questo lavoro può anche consentire l'identificazione di importanti elementi del sistema immunitario in grado di promuovere la progressione del tumore.
In several human cancer types and in tumor-bearing mouse models, tumor-derived factors sustain the accumulation and functional differentiation of myeloid cells, including myeloid-derived suppressor cells (MDSCs), which can interfere with T cell-mediated responses. The aim of this study was to characterize MDSCs presence in the circulation of pancreatic ductal adenocarcinoma (PDAC) patients and to evaluate their importance as biomarkers. Our results show that monocytic MDSC (MO-MDSC) are significantly expanded in PDAC patient compared to healthy controls. Within the PDAC donors, a group displays monocytes with immune suppressive ability on T cells and this phenotype is accompanied with a specific gene expression profile different from that of non-suppressive cells both of patients and control origin. Our observations suggest that a specific genetic “barcode” identify suppressive PDAC MO-MDSC and this tool can potentially be used as prognostic factor as well as important additional information regarding the need of an immunological treatment or co-treatment of pancreatic cancer. The dynamic interplay between human cancer and host immune system can be studied in vivo in mice repopulated with human hematopoietic cells (HIR mice). Here we describe an easy tool to sustain human myelopoiesis in these models delivering human cytokines via adeno associated virus (AAV) and we apply it for the study of pancreatic cancer. We show that the presence of the human immune system promotes cancer progression, as lung micrometastasis frequency is significantly increased in tumor-bearing HIR mice compared to controls. Human leukocytes that infiltrate the pre-metastatic niche are characterized by a genetic signature strongly related to the myeloid compartment and to inflammation. Among the upregulated factors, we find protein S100B, whose serum level is also significantly different compared to control and chronic pancreatitis patients. This study opens up new possibilities for the characterization of a genetic "barcode" useful to identify suppressive MO-MDSC in patients with pancreatic adenocarcinoma. This work may also enable the identification of important elements of the immune system that can promote tumor progression.