Françoise Silvy

Exosomal Lipids Impact Notch Signaling and Induce Death of Human Pancreatic Tumoral SOJ-6 Cells

Exosomes are of increasing interest as alternative mode of cell-to-cell communication. We previously reported that exosomes secreted by human SOJ-6 pancreatic tumor cells induce (glyco)protein ligand-independent cell death and inhibit Notch-1 pathway, this latter being particularly active during carcinogenesis and in cancer stem cells. Therefore, we asked whether exosomal lipids were key-elements for cell death and hypothesized that cholesterol-rich membrane microdomains were privileged sites of exosome interactions with tumor cells. To address these questions and based on the lipid composition of exosomes from SOJ-6 cells (Ristorcelli et al. (2008) FASEB J. 22; 3358–3369) enriched in cholesterol and sphingomyelin (lipids forming liquid-ordered phase, Lo) and depleted in phospholipids (lipids forming liquid-disordered phase, Ld), we designed Synthetic Exosome-Like Nanoparticles (SELN) with ratios Lo/Ld from 3.0 to 6.0 framing that of SOJ-6 cell exosomes. SELN decreased tumor cell survival, the higher the Lo/Ld ratio, the lower the cell survival. This decreased survival was due to activation of cell death with inhibition of Notch pathway. FRET analyses indicated fusions/exchanges of SELN with cell membranes. Fluorescent SELN co-localized with the ganglioside GM1 then with Rab5A, markers of lipid microdomains and of early endosomes, respectively. These interactions occurred at lipid microdomains of plasma and/or endosome membranes where the Notch-1 pathway matures. We thus demonstrated a major role for lipids in interactions between SELN and tumor cells, and in the ensued cell death. To our knowledge this is the first report on such effects of lipidic nanoparticles on tumor cell behavior. This may have implications in tumor progression.

Resistance to cisplatin‐induced cell death conferred by the activity of organic anion transporting polypeptides (OATP) in human melanoma cells

Expression of organic anion transporting polypeptides (OATP) transporters can be modified with potential incidence in cancers, yet they have not been considered in melanoma. Here, we demonstrate transcriptional and protein expression of OATP members in human melanoma cell lines with sodium‐independent organic anion uptake activity. Importantly, uptake of different organic anions over 24 h led to a common resistance signal to apoptotic cell death, induced further by cisplatin in 24 h. The mechanism is not dependent on the transport of cisplatin by the OATP, as it is not an OATP substrate. The resistance signal was modulated by PKC, disclosing it as signal mediator. This study suggests that OATP, which can be constantly activated by endobiotics, may contribute to melanoma chemotherapeutic resistance, thereby justifying the development of OATP targeting strategies.

Rs488087 single nucleotide polymorphism as predictive risk factor for pancreatic cancers

Pancreatic cancer (PC) is a devastating disease progressing asymptomatically until death within months after diagnosis. Defining at-risk populations should promote its earlier diagnosis and hence also avoid its development. Considering the known involvement in pancreatic disease of exon 11 of the bile salt-dependent lipase (BSDL) gene that encodes variable number of tandem repeat (VNTR) sequences, we hypothesized upon the existence of a genetic link between predisposition to PC and mutations in VNTR loci. To test this, BSDL VNTR were amplified by touchdown-PCR performed on genomic DNA extracted from cancer tissue or blood samples from a French patient cohort and amplicons were Sanger sequenced. A robust method using probes for droplet digital (dd)-PCR was designed to discriminate the C/C major from C/T or T/T minor genotypes. We report that the c.1719C > T transition (SNP rs488087) present in BSDL VNTR may be a useful marker for defining a population at risk of developing PC (occurrence: 63.90% in the PC versus 27.30% in the control group). The odds ratio of 4.7 for the T allele was larger than those already determined for other SNPs suspected to be predictive of PC. Further studies on tumor pancreatic tissue suggested that a germline T allele may favor Kras G12R/G12D somatic mutations which represent negative prognostic factors associated with reduced survival. We propose that the detection of the T allele in rs488087 SNP should lead to an in-depth follow-up of patients in whom an association with other potential risk factors of pancreatic cancer may be present.

A Novel Tumor-Associated Pancreatic Glycoprotein Is Internalized by Human Dendritic Cells and Induces Their Maturation

Aberrant glycosylation or overexpression of cell-surface glycosylated tumor-associated Ags (TAA) distinguish neoplastic from normal cells. Interactions of TAA MUC1 and HER2/neu with dendritic cells (DC) preclude efficient processing, which impairs immune responses. It is thus important to define the mechanisms of interactions between DC and glycosylated TAA and their trafficking and processing for further T cell activation. In this work, we study interactions between DC and the oncofetal fucose-rich glycovariants of bile salt-dependent lipase (BSDL), expressed in pancreatic cancer tissues and referred to as pathological BSDL carrying the fucosylated J28 glycotope (pBSDL-J28) because it is characterized by the mAb J28. The expression of pBSDL-J28 was assessed by immunohistochemistry and quantified by confocal microscopy. Nontumoral pancreatic tissues and cells do not express pBSDL-J28. Using multidisciplinary approaches and functional studies, we provide the first evidence, to our knowledge, that this tumoral glycoprotein is rapidly internalized by human DC through macropinocytosis and endocytosis via mannose receptors and then transported to late endosomes for processing. Interestingly, pBSDL-J28 per se induced DC maturation with increased expression of costimulatory and CD83 molecules associated with cytokine secretion (IL-8 and IL-6). Surprisingly, DC retained their full ability to internalize Ags, making this maturation atypical. Finally, the allogeneic pBSDL-J28–treated DC stimulated lymphocyte proliferation. Besides, pulsing DC with pBSDL-J28 C-terminal glycopolypeptide and maturation with CD40L triggered CD4+ and CD8+ T cell proliferation. Therefore, interactions of pBSDL-J28, expressed on tumoral pancreatic tissue, with DC may lead to adequate Ag trafficking and processing and result in T cell activation.

Monoclonal antibody 16D10 to the COOH-terminal domain of the feto-acinar pancreatic protein targets pancreatic neoplastic tissues

We have shown that the 16D10 antigen located on the mucin-like COOH-terminal domain of the feto-acinar pancreatic protein (FAPP) is expressed at the surface of human pancreatic tumor cell lines such as SOJ-6 cell line. Furthermore, an in vivo study indicates that targeting this cell-membrane glycopeptide by the use of the monoclonal antibody (mAb) 16D10 inhibits the growth of SOJ-6 xenografts in nude mice. To validate the potential use of the mAb16D10 in immune therapy, this study examined the expression of 16D10 antigens at the surface of human pancreatic adenocarcinomas versus control tissues. We examined the reactivity of mAb16D10 and mAb8H8 with pancreatic ductal adenocarcinomas (PDAC) compared with controls by using immunohistochemistry and confocal laser scanning microscopy. mAb8H8 does react with control or nontumoral human pancreatic tissues. mAb16D10 has a strong and specific reactivity with PDAC and does not react with other cancers of epithelia or normal tissues tested. Notable, mAb16D10 mostly recognizes membrane of tumoral cells. Furthermore, mAb8H8 and mAb16D10 recognized a protein of 110 to 120 kDa in homogenates of nontumoral and tumoral human pancreatic tissues, respectively. This size correlates with that of FAPP or with that of the normal counterpart of FAPP, the so-called bile salt-dependent lipase. The results suggest that mAb16D10 presents a unique specificity against PDAC; consequently, it could be effective in immune therapy of this cancer. Furthermore, mAb16D10 and mAb8H8 pair might be useful for diagnosis purpose in discriminating tumoral from nontumoral human pancreatic tissues. [Mol Cancer Ther 2009;8(2):282–91]

Saccharomyces boulardii CNCM I-745 Restores intestinal Barrier Integrity by Regulation of E-cadherin Recycling

Background and Aims Alteration in intestinal permeability is the main factor underlying the pathogenesis of many diseases affecting the gut, such as inflammatory bowel disease [IBD]. Characterization of molecules targeting the restoration of intestinal barrier integrity is therefore vital for the development of alternative therapies. The yeast Saccharomyces boulardii CNCM I-745 [Sb], used to prevent and treat antibiotic-associated infectious and functional diarrhea, may have a beneficial effect in the treatment of IBD. Methods We analyzed the impact of Sb supernatant on tissue integrity and components of adherens junctions using cultured explants of colon from both IBD and healthy patients. To evaluate the pathways by which Sb regulates the expression of E-cadherin at the cell surface, we developed in vitro assays using human colonic cell lines, including cell aggregation, a calcium switch assay, real-time measurement of transepithelial electrical resistance [TEER] and pulse-chase experiments. Results We showed that Sb supernatant treatment of colonic explants protects the epithelial morphology and maintains E-cadherin expression at the cell surface. In vitro experiments revealed that Sb supernatant enhances E-cadherin delivery to the cell surface by re-routing endocytosed E-cadherin back to the plasma membrane. This process, involving Rab11A-dependent recycling endosome, leads to restoration of enterocyte adherens junctions, in addition to the overall restoration and strengthening of intestinal barrier function. Conclusion These findings open new possibilities of discovering novel options for prevention and therapy of diseases that affect intestinal permeability.

Expression of truncated bile salt-dependent lipase variant in pancreatic pre-neoplastic lesions.

Pancreatic adenocarcinoma (PDAC) is a dismal disease. The lack of specific symptoms still leads to a delay in diagnosis followed by death within months for most patients. Exon 11 of the bile salt-dependent lipase (BSDL) gene encoding variable number of tandem repeated (VNTR) sequences has been involved in pancreatic pathologies. We hypothesized that BSDL VNTR sequences may be mutated in PDAC. The amplification of BSDL VNTR from RNA extracted from pancreatic SOJ-6 cells allowed us to identify a BSDL amplicon in which a cytosine residue is inserted in a VNTR sequence. This insertion gives rise to a premature stop codon, resulting in a truncated protein and to a modification of the C-terminal amino-acid sequence; that is PRAAHG instead of PAVIRF. We produced antibodies directed against these sequences and examined pancreatic tissues from patients with PDAC and PanIN. Albeit all tissues were positive to anti-PAVIRF antibodies, 72.2% of patient tissues gave positive reaction with anti-PRAAHG antibodies, particularly in dysplastic areas of the tumor. Neoplastic cells with ductal differentiation were not reactive to anti-PRAAHG antibodies. Some 70% of PanIN tissues were also reactive to anti-PRAAHG antibodies, suggesting that the C insertion occurs early during pancreatic carcinogenesis. Data suggest that anti-PRAAHG antibodies were uniquely reactive with a short isoform of BSDL specifically expressed in pre-neoplastic lesions of the pancreas. The detection of truncated BSDL reactive to antibodies against the PRAAHG C-terminal sequence in pancreatic juice or in pancreatic biopsies may be a new tool in the early diagnosis of PDAC.

Dendritic cell-based vaccination: powerful resources of immature dendritic cells against pancreatic adenocarcinoma

ABSTRACT Pancreatic adenocarcinoma (PAC) has a poor prognosis. One treatment approach, investigated here, is to reinforce antitumor immunity. Dendritic cells (DCs) are essential for the development and regulation of adaptive host immune responses against tumors. A major role for DCs may be as innate tumoricidal effector cells. We explored the efficacy of vaccination with immature (i)DCs, after selecting optimal conditions for generating immunostimulatory iDCs. We used two models, C57BL/6Jrj mice with ectopic tumors induced by the PAC cell line, Panc02, and genetically engineered (KIC) mice developing PAC. Therapeutic iDC-vaccination resulted in a significant reduction in tumor growth in C57BL/6Jrj mice and prolonged survival in KIC mice. Prophylactic iDC-vaccination prevented subcutaneous tumor development. These protective effects were long-lasting in Panc02-induced tumor development, but not in melanoma. iDC-vaccination impacted the immune status of the hosts by greatly increasing the percentage of CD8+ T-cells, and natural killer (NK)1.1+ cells, that express granzyme B associated with Lamp-1 and IFN-γ. Efficacy of iDC-vaccination was CD8+ T-cell-dependent but NK1.1+ cell-independent. We demonstrated the ability of DCs to produce peroxynitrites and to kill tumor cells; this killing activity involved peroxynitrites. Altogether, these findings make killer DCs the pivotal actors in the beneficial clinical outcome that accompanies antitumor immune responses. We asked whether efficacy can be improved by combining DC-vaccination with the FOLFIRINOX regimen. Combined treatment significantly increased the lifespan of KIC mice with PAC. Prolonged treatment with FOLFIRINOX clearly augmented this beneficial effect. Combining iDC-vaccination with FOLFIRINOX may therefore represent a promising therapeutic option for patients with PAC.

Pancreatic adenocarcinoma, chronic pancreatitis, and MODY-8 diabetes: is bile salt-dependent lipase (or carboxyl ester lipase) at the crossroads of pancreatic pathologies?

Pancreatic adenocarcinomas and diabetes mellitus are responsible for the deaths of around two million people each year worldwide. Patients with chronic pancreatitis do not die directly of this disease, except where the pathology is hereditary. Much current literature supports the involvement of bile salt-dependent lipase (BSDL), also known as carboxyl ester lipase (CEL), in the pathophysiology of these pancreatic diseases. The purpose of this review is to shed light on connections between chronic pancreatitis, diabetes, and pancreatic adenocarcinomas by gaining an insight into BSDL and its variants. This enzyme is normally secreted by the exocrine pancreas, and is diverted within the intestinal lumen to participate in the hydrolysis of dietary lipids. However, BSDL is also expressed by other cells and tissues, where it participates in lipid homeostasis. Variants of BSDL resulting from germline and/or somatic mutations (nucleotide insertion/deletion or nonallelic homologous recombination) are expressed in the pancreas of patients with pancreatic pathologies such as chronic pancreatitis, MODY-8, and pancreatic adenocarcinomas. We discuss the possible link between the expression of BSDL variants and these dramatic pancreatic pathologies, putting forward the suggestion that BSDL and its variants are implicated in the cell lipid metabolism/reprogramming that leads to the dyslipidemia observed in chronic pancreatitis, MODY-8, and pancreatic adenocarcinomas. We also propose potential strategies for translation to therapeutic applications.