Tumor-stroma Crosstalk Research Articles

Breast cancer stem cells: Biology and therapeutic implications.

Breast cancer remains to be a dreadful disease even with several advancements in radiation and chemotherapies, owing to the drug resistance and tumor relapse caused by breast cancer stem cells. Cancer stem cells are a minute population of cells of solid tumors which show self-renewal and differentiation properties as well as tumorigenic potential. Several signaling pathways including Notch, Hippo, Wnt and Hedgehog and tumor-stroma exchanges play a critical role in the self-renewal and differentiation of cancer stem cells in breast cancer. Cancer stem cells can grow anchorage-independent manner so they disseminate to different parts of the body to form secondary tumors. Cancer stem cells promote angiogenesis by dedifferentiating to endothelial cells as well as secreting proangiogenic and angiogenic factors. Moreover, multidrug resistance genes and drug efflux transporters expressed in breast cancer stem cells confer resistance to various conventional chemotherapeutic drugs. Indeed, these therapies are recognised to enhance the percent of cancer stem cell population in tumors leading to cancer relapse with increased aggressiveness. Hence, devising the therapeutic interventions to target cancer stem cells would be useful in increasing patients' survival rates. In addition, targeting the self-renewal pathways and tumor-stromal cross-talk helps in eradicating this population. Reversal of the cancer stem cell-mediated drug resistance would increase the sensitivity to various conventional drugs for the effective management of breast cancer. In this review, we have discussed the cancer stem cell origin and their involvement in angiogenesis, metastasis and therapy-resistance. We have also summarized different therapeutic approaches to eradicate the same for the successful treatment of breast cancer.

S100A8 and S100A9 proteins form part of a paracrine feedback loop between pancreatic cancer cells and monocytes

BackgroundThe secretion of soluble factors enables communication between tumour cells and the surrounding microenvironment and plays an important role in oncogenesis. Pancreatic ductal adenocarcinoma (PDAC) is characterised by a highly reactive microenvironment, harbouring a variety of cell types, including S100A8/S100A9-expressing monocytes. S100A8/S100A9 proteins regulate the behaviour of cancer cells by inducing pre-metastatic cascades associated with cancer spread. The aim of this study was to examine how S100A8/A9 proteins mediate tumour-stroma crosstalk in PDAC.MethodsCytokine profiling of pancreatic cancer cell-derived conditioned media was performed using Bio-Plex Pro 27 Plex Human Cytokine assays. Protein expression and activation of downstream signalling effectors and NF-κB were assessed by western blotting analysis and reporter assays respectively.ResultsStimulation of cultured pancreatic cancer cells with S100A8 and S100A9 increased the secretion of the pro-inflammatory cytokines IL-8, TNF-α, and FGF. S100A8, but not S100A9 induced PDGF secretion. Conversely, pancreatic cancer cell-derived conditioned media and the individual cytokines, TNF-α and TGF-β induced the expression of S100A8 and S100A9 proteins in the HL-60 monocytic cell line and primary human monocytes, while FGF and IL-8 induced the expression of S100A9 only. S100A8 and S100A9 activated MAPK and NF-κB signalling in pancreatic cancer. This was partially mediated via activation of the receptor of advanced glycosylation end-product (RAGE).ConclusionS100A8 and S100A9 proteins induce specific cytokine secretion from PDAC cells, which in turn enhances the expression of S100A8/A9. This paracrine crosstalk could have implications for PDAC invasiveness and metastatic potential.

The Role of Melanoma Cell-Stroma Interaction in Cell Motility, Invasion, and Metastasis.

The importance of studying cancer cell invasion is highlighted by the fact that 90% of all cancer-related mortalities are due to metastatic disease. Melanoma metastasis is driven fundamentally by aberrant cell motility within three-dimensional or confined environments. Within this realm of cell motility, cytokines, growth factors, and their receptors are crucial for engaging signaling pathways, which both mediate crosstalk between cancer, stromal, and immune cells in addition to interactions with the surrounding microenvironment. Recently, the study of the mechanical biology of tumor cells, stromal cells and the mechanics of the microenvironment have emerged as important themes in driving invasion and metastasis. While current anti-melanoma therapies target either the MAPK signaling pathway or immune checkpoints, there are no drugs available that specifically inhibit motility and thus invasion and dissemination of melanoma cells during metastasis. One of the reasons for the lack of so-called “migrastatics” is that, despite decades of research, the precise biology of metastatic disease is still not fully understood. Metastatic disease has been traditionally lumped into a single classification, however what is now emergent is that the biology of melanoma metastasis is highly diverse, heterogeneous and exceedingly dynamic—suggesting that not all cases are created equal. The following mini-review discusses melanoma heterogeneity in the context of the emergent theme of mechanobiology and how it influences the tumor-stroma crosstalk during metastasis. Thus, highlighting future therapeutic options for migrastatics and mechanomedicines in the prevention and treatment of metastatic melanoma.

Derivation and Validation of the Potential Core Genes in Pancreatic Cancer for Tumor-Stroma Crosstalk.

Background Pancreatic cancer is a fatal malignancy with a poor prognosis. The interactions between tumor cells and stromal cells contribute to cancer progression. Pancreatic stellate cells (PSCs) play a key role in tumor-stroma crosstalk of pancreatic cancer. The in-depth exploration for tumor-stroma crosstalk is helpful to develop novel therapeutic strategies. Our aim was to identify the potential core genes and pathways in tumor-stroma crosstalk. Methods 3 microarray datasets were from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were screened through bioinformatics analysis. Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and protein-protein interaction (PPI) network were used to obtain the biological roles of DEGs. The top 15 DEGs were explored by principal component analysis. We validated the top 15 DEGs expression in the tumor-stroma crosstalk model in which PSCs were treated with the mixture of Aspc-1 and Panc-1 supernatant. Results A total of 221 genes were filtered as DEGs for tumor-stroma crosstalk. The results of principal component analysis for the top 15 DEGs can distinguish three groups. According to the KEGG enrichment, there were 8, 7, and 7 DEGs enriched in cancer related pathway, PI3K-Akt signaling pathway, and microRNAs, respectively. In the tumor-stroma crosstalk model, significant differences can be validated in the AKAP12, CLDN1, CP, FKBP1A, LAMB3, LSM4, MTMR3, PRKARIA, YWHAZ, and JUND expressions. Conclusions These results identified the potential core genes and pathways in pancreatic cancer for tumor-stroma crosstalk, which could provide potential targets for the treatment of pancreatic cancer.

Tumor Microenvironment Targeted Nanotherapy.

Recent developments in nanotechnology have brought new approaches to cancer diagnosis and therapy. While enhanced permeability and retention effect promotes nano-chemotherapeutics extravasation, the abnormal tumor vasculature, high interstitial pressure and dense stroma structure limit homogeneous intratumoral distribution of nano-chemotherapeutics and compromise their imaging and therapeutic effect. Moreover, heterogeneous distribution of nano-chemotherapeutics in non-tumor-stroma cells damages the non-tumor cells, and interferes with tumor-stroma crosstalk. This can lead not only to inhibition of tumor progression, but can also paradoxically induce acquired resistance and facilitate tumor cell proliferation and metastasis. Overall, the tumor microenvironment plays a vital role in regulating nano-chemotherapeutics distribution and their biological effects. In this review, the barriers in tumor microenvironment, its consequential effects on nano-chemotherapeutics, considerations to improve nano-chemotherapeutics delivery and combinatory strategies to overcome acquired resistance induced by tumor microenvironment have been summarized. The various strategies viz., nanotechnology based approach as well as ligand-mediated, redox-responsive, and enzyme-mediated based combinatorial nanoapproaches have been discussed in this review.

Tumor⁻Stroma Cross-Talk in Human Pancreatic Ductal Adenocarcinoma: A Focus on the Effect of the Extracellular Matrix on Tumor Cell Phenotype and Invasive Potential.

The extracellular matrix (ECM) in the tumor microenvironment modulates the cancer cell phenotype, especially in pancreatic ductal adenocarcinoma (PDAC), a tumor characterized by an intense desmoplastic reaction. Because the epithelial-to-mesenchymal transition (EMT), a process that provides cancer cells with a metastatic phenotype, plays an important role in PDAC progression, the authors aimed to explore in vitro the interactions between human PDAC cells and ECM components of the PDAC microenvironment, focusing on the expression of EMT markers and matrix metalloproteinases (MMPs) that are able to digest the basement membrane during tumor invasion. EMT markers and the invasive potential of HPAF-II, HPAC, and PL45 cells grown on different ECM substrates (fibronectin, laminin, and collagen) were analyzed. While N-cadherin, αSMA, and type I collagen were not significantly affected by ECM components, the E-cadherin/β-catenin complex was highly expressed in all the experimental conditions, and E-cadherin was upregulated by collagen in PL45 cells. Cell migration was unaffected by fibronectin and delayed by laminin. In contrast, collagen significantly stimulated cell migration and the secretion of MMPs. This study’s results showed that ECM components impacted cell migration and invasive potential differently. Collagen exerted a more evident effect, providing new insights into the understanding of the intricate interplay between ECM molecules and cancer cells, in order to find novel therapeutic targets for PDAC treatment.

A miR-125b/CSF1-CX3CL1/tumor-associated macrophage recruitment axis controls testicular germ cell tumor growth

Tumor growth is modulated by crosstalk between cancer cells and the tumor microenvironment. Recent advances have shown that miRNA dysfunction in tumor cells can modulate the tumor microenvironment to indirectly determine their progression. However, this process is poorly understood in testicular germ cell tumors (TGCTs). We reported here that miR-125b was repressed in TGCT samples by epigenetic modifications rather than genetic alternations. Furthermore, miR-125b overexpression significantly alleviated the tumor growth in two NCCIT human embryonic carcinoma xenograft models in vivo, whereas miR-125b did not stimulate autonomous tumor cell growth in vitro. Notably, forced expression of miR-125b in NCCIT embryonic carcinoma cells decreased the abundance of host tumor-associated macrophages (TAMs) within tumor microenvironment. Selective deletion of host macrophages by clodronate abolished the anti-tumoral ability of miR-125b in xenograft models. By RNA profiling, Western blot and luciferase reporter assay, we further observed that miR-125b directly regulated tumor cell-derived chemokine CSF1 and CX3CL1, which are known to control the recruitment of TAMs to tumor sites. Lastly, we found that one set of miRNAs, which are under the regulation of miR-125b, might convergently target CSF1/CX3CL1 in NCCIT cells using miRNA profiling. These findings uncover the anticancer effect of miR-125b via mediating tumor-stroma crosstalk in xenograft models of TGCTs and raise the possibility of targeting miR-125b as miRNA therapeutics.

Diagnostic role of circulating extracellular matrix-related proteins in non-small cell lung cancer

BackgroundInteractions between cancer cells and the surrounding microenvironment are crucial determinants of cancer progression. During this process, bi-directional communication among tumor cells and cancer associated fibroblasts (CAF) regulate extracellular matrix (ECM) deposition and remodeling. As a result of this dynamic process, soluble ECM proteins can be released into the bloodstream and may represent novel circulating biomarkers useful for cancer diagnosis. The aim of the present study was to measure the levels of three circulating ECM related proteins (COL11A1, COL10A1 and SPARC) in plasma samples of lung cancer patients and in healthy heavy-smokers controls and test whether such measurements have diagnostic or prognostic value.MethodsGene expression profiling of lung fibroblasts isolated from paired normal and cancer tissue of NSCLC patients was performed by gene expression microarrays. The prioritization of the candidates for the study of circulating proteins in plasma was based on the most differentially expressed genes in cancer associated fibroblasts. Soluble ECM proteins were assessed by western blot in the conditioned medium of lung fibroblasts and by ELISA assays in plasma samples.ResultsPlasma samples from lung cancer patients and healthy heavy-smokers controls were tested for levels of COL11A1 and COL10A1 (n = 57 each) and SPARC (n = 90 each). Higher plasma levels of COL10A1 were detected in patients (p ≤ 0.001), a difference that was driven specifically by females (p < 0.001). No difference in COL11A1 levels between patients and controls was found. SPARC levels were also higher in plasma patients than controls (p < 0.001) with good performance in discriminating the two groups (AUC = 0.744). No significant association was observed between plasma proteins levels and clinicopathological features or survival.ConclusionSoluble factors related to proficient tumor-stroma cross-talk are detectable in plasma of primary lung cancer patients and may represent a valuable complementary diagnostic tool to discriminate lung cancer patients from healthy heavy-smokers individuals as shown for the SPARC protein.

Missed Druggable Cancer Hallmark: Cancer-Stroma Symbiotic Crosstalk as Paradigm and Hypothesis for Cancer Therapy.

During tumor evolution, cancer cells use the tumor-stroma crosstalk to reorganize the microenvironment for maximum robustness of the tumor. The success of immune checkpoint therapy foretells a new cancer therapy paradigm: an effective cancer treatment should not aim to influence the individual components of super complex intracellular interactomes (molecular targeting), but try to disrupt the intercellular interactions between cancer and stromal cells, thus breaking the tumor as a whole. Arguments are provided in favor of a hypothesis that such interactions include formation of synapse-like structures (interfaces) where the interacting cells are located at a distance of ∼10-15 nm. Within these interfaces, molecules initiating and strengthening the interaction are organized, and allow optimum cross-signaling; a very confined intercellular space facilitates the concentration of secreted cytokines, enhancing the paracrine cross-communication. These features of tumors form a druggable cancer hallmark the tumor-stroma symbiotic crosstalk-which represents a new target for efficient cancer drug discovery.

Laminin α1 orchestrates VEGFA functions in the ecosystem of colorectal carcinoma.

Tumor stroma remodeling is a key feature of malignant tumors and can promote cancer progression. Laminins are major constituents of basement membranes that physically separate the epithelium from the underlying stroma. By employing mouse models expressing high and low levels of the laminin α1 chain (LMα1), we highlighted its implication in a tumor-stroma crosstalk, thus leading to increased colon tumor incidence, angiogenesis and tumor growth. The underlying mechanism involves attraction of carcinoma-associated fibroblasts by LMα1, VEGFA expression triggered by the complex integrin α2β1-CXCR4 and binding of VEGFA to LM-111, which in turn promotes angiogenesis, tumor cell survival and proliferation. A gene signature comprising LAMA1, ITGB1, ITGA2, CXCR4 and VEGFA has negative predictive value in colon cancer. Together, we have identified VEGFA, CXCR4 and α2β1 integrin downstream of LMα1 in colon cancer as of bad prognostic value for patient survival. This information opens novel opportunities for diagnosis and treatment of colon cancer.

Abstract 198: MUC13 promotes pancreatic tumor-stromal interactions by influencing tumor microenvironment

Abstract Objective: Pancreatic cancer (PanCa) is the third leading cause of cancer-related deaths in the U.S. MUC13, mucin, is aberrantly expressed in PanCa and its overexpression leads to tumorigenic and metastatic behavior of cancer cells. Herein, we investigate the role of MUC13 in tumor microenvironment (TME) that favors PanCa progression/metastasis and drug resistance. Methods: MUC13 expressing (Panc-1) and knockdown PanCa cells (HPAF-II) and pancreatic stromal cells (PSCs), derived from freshly collected human pancreatic tissues, were utilized for the study. Using immunoblotting, ELISA, qPCR and RT-PCR techniques, we assessed the MUC13-induced alterations in the expression of important molecules that are involved in promotion of pancreatic tumor stromal interactions and drug resistance. Cytation 3 live cell imaging was performed for 3D tumor-stromal cell co-culture and invasion assays. Xenograft mice tumor tissues generated using ectopically expressing MUC13 and null cells were used for the study. Results: Our results demonstrate that MUC13 activates SHH signaling pathway in PanCa cells via upregulation of SHH and its related important downstream targets such as CXCR-4, Gli-1, SMO, PTCH1/2, NFκB and p-AKT in PanCa cells using immunoblotting and PCR. We also observed increased expression of SHH, Gli-1, CXCR-4 and α-SMA in MUC13-expressing xenograft tumors using Immunohistochemistry. Ectopic MUC13-expressing PanCa cells grown in co-culture with PSCs showed enhanced secretion of IL-6 and CXCL-12 (ELISA), increase in invasion (Matrigel invasion assay) and migratory (Boyden chamber assay) potential of both the cultured PanCa as well as stromal cells. Additionally, ectopically MUC13-expressing cells were resistant to treatment with gemcitabine as depicted by proliferation assay and qPCR results showed enhanced expression of ribonucleoside-diphosphate reductase (RRM1/2) and miR-21, which are known to be involved in gemcitabine resistance. Overall, our results suggest that MUC13 modulates tumor-stromal crosstalk, promoting tumor growth, invasion and drug resistance in TME. Conclusion: Our results suggest that MUC13 expression might influence signaling supportive of interactive TME, leading to increased tumor growth and drug resistance. These findings illustrate mechanisms by which MUC13 promotes tumorigenic TME and contributes to PanCa cell survival, metastasis and drug resistance. Citation Format: Sheema S. Khan, Kyle Doxtater, Sonam Kumari, Saini Setua, Mohammed Sikander, Shabnam Malik, Murali Yallapu, Stephen Behrman, Subhash Chauhan, Meena Jaggi. MUC13 promotes pancreatic tumor-stromal interactions by influencing tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 198.

Targeting galectin-1 inhibits pancreatic cancer progression by modulating tumor–stroma crosstalk

Pancreatic ductal adenocarcinoma (PDA) remains one of the most lethal tumor types, with extremely low survival rates due to late diagnosis and resistance to standard therapies. A more comprehensive understanding of the complexity of PDA pathobiology, and especially of the role of the tumor microenvironment in disease progression, should pave the way for therapies to improve patient response rates. In this study, we identify galectin-1 (Gal1), a glycan-binding protein that is highly overexpressed in PDA stroma, as a major driver of pancreatic cancer progression. Genetic deletion of Gal1 in a Kras-driven mouse model of PDA (Ela-KrasG12Vp53-/- ) results in a significant increase in survival through mechanisms involving decreased stroma activation, attenuated vascularization, and enhanced T cell infiltration leading to diminished metastasis rates. In a human setting, human pancreatic stellate cells (HPSCs) promote cancer proliferation, migration, and invasion via Gal1-driven pathways. Moreover, in vivo orthotopic coinjection of pancreatic tumor cells with Gal1-depleted HPSCs leads to impaired tumor formation and metastasis in mice. Gene-expression analyses of pancreatic tumor cells exposed to Gal1 reveal modulation of multiple regulatory pathways involved in tumor progression. Thus, Gal1 hierarchically regulates different events implicated in PDA biology including tumor cell proliferation, invasion, angiogenesis, inflammation, and metastasis, highlighting the broad therapeutic potential of Gal1-specific inhibitors, either alone or in combination with other therapeutic modalities.

SAT-150 - Tumor-stroma crosstalk enhances Reg3A expressions that drives the progression of hepatocellular carcinoma

SAT-150 - Tumor-stroma crosstalk enhances Reg3A expressions that drives the progression of hepatocellular carcinoma

MiR-16 regulates the pro-tumorigenic potential of lung fibroblasts through the inhibition of HGF production in an FGFR-1- and MEK1-dependent manner

BackgroundFibroblasts are crucial mediators of tumor-stroma cross-talk through synthesis and remodeling of the extracellular matrix and production of multiple soluble factors. Nonetheless, little is still known about specific determinants of fibroblast pro-tumorigenic activity in lung cancer. Here, we aimed at understanding the role of miRNAs, which are often altered in stromal cells, in reprogramming fibroblasts towards a tumor-supporting phenotype.MethodsWe employed a co-culture-based high-throughput screening to identify specific miRNAs modulating the pro-tumorigenic potential of lung fibroblasts. Multiplex assays and ELISA were instrumental to study the effect of miRNAs on the secretome of both primary and immortalized lung fibroblasts from lung cancer patients and to evaluate plasmatic levels of HGF in heavy smokers. Direct mRNA targeting by miRNAs was investigated through dual-luciferase reporter assay and western blot. Finally, the pro-tumorigenic activity of fibroblasts and their conditioned media was tested by employing in vitro migration experiments and mouse xenografts.ResultsWe identified miR-16 as a master regulator of fibroblast secretome and showed that its upregulation reduces HGF secretion by fibroblasts, impairing their capacity to promote cancer cell migration. This effect is due to a pleiotropic activity of miR-16 which prevents HGF expression through direct inhibition of FGFR-1 signaling and targeting of HGF mRNA. Mechanistically, miR-16 targets FGFR-1 downstream mediator MEK1, thus reducing ERK1/2 activation. Consistently, chemical or genetic inhibition of FGFR-1 mimics miR-16 activity and prevents HGF production. Of note, we report that primary fibroblast cell lines derived from lungs of heavy smokers express reduced miR-16 levels compared to those from lungs not exposed to smoke and that HGF concentration in heavy smokers’ plasma correlates with levels of tobacco exposure. Finally, in vivo experiments confirmed that restoration of miR-16 expression in fibroblasts reduced their ability to promote tumor growth and that HGF plays a central role in the pro-tumorigenic activity of fibroblasts.ConclusionsOverall, these results uncover a central role for miR-16 in regulating HGF production by lung fibroblasts, thus affecting their pro-tumorigenic potential. Correlation between smoking exposure and miR-16 levels could provide novel clues regarding the formation of a tumor-proficient milieu during the early phases of lung cancer development.

Resveratrol suppresses migration, invasion and stemness of human breast cancer cells by interfering with tumor-stromal cross-talk

Cancer-associated fibroblasts (CAFs) constitute a major compartment of the tumor microenvironment. CAFs produce a variety of cytokines, growth factors and extracellular matrix proteins, thereby stimulating tumor progression. CAFs are distinct from normal fibroblasts for their overexpression of α-smooth muscle actin. Recent studies suggest that CAFs play an important role in proliferation and migration of cancer cells through cross-talk with them. Resveratrol (trans-3,4′5,-trihydroxystilbene), a phytoalexin present in grapes, has been reported to possess chemopreventive and chemotherapeutic activities. In the present study, we examined the effects of resveratrol on CAF-induced migration, invasion and self-renewal activity of breast cancer cells. Resveratrol inhibited proliferation, migration and invasion of human breast cancer cells treated with CAF-conditioned media (CAF-CM). Resveratrol treatment suppressed the CAF-CM-induced expression of Cyclin D1, c-Myc, MMP-2 and MMP-9. In addition, resveratrol inhibited Sox2 expression as well as activation of Akt and STAT3 induced by CAF-CM in breast cancer cells. Further, resveratrol abrogated stemness properties and reduced the expression of self-renewal signaling molecules in stem-like breast cancer cells. Taken together, the present study provides insights into the role of resveratrol in tumor microenvironment with focus on interaction between cancer cells and the hosting niche.

Inactivation of Cancer-Associated-Fibroblasts Disrupts Oncogenic Signaling in Pancreatic Cancer Cells and Promotes Its Regression.

Resident fibroblasts that contact tumor epithelial cells (TEC) can become irreversibly activated as cancer-associated-fibroblasts (CAF) that stimulate oncogenic signaling in TEC. In this study, we evaluated the cross-talk between CAF and TEC isolated from tumors generated in a mouse model of KRAS/mut p53-induced pancreatic cancer (KPC mice). Transcriptomic profiling conducted after treatment with the anticancer compound Minnelide revealed deregulation of the TGFβ signaling pathway in CAF, resulting in an apparent reversal of their activated state to a quiescent, nonproliferative state. TEC exposed to media conditioned by drug-treated CAFs exhibited a decrease in oncogenic signaling, as manifested by downregulation of the transcription factor Sp1. This inhibition was rescued by treating TEC with TGFβ. Given promising early clinical studies with Minnelide, our findings suggest that approaches to inactivate CAF and prevent tumor-stroma cross-talk may offer a viable strategy to treat pancreatic cancer.Significance: In an established mouse model of pancreatic cancer, administration of the promising experimental drug Minnelide was found to actively deplete reactive stromal fibroblasts and to trigger tumor regression, with implications for stromal-based strategies to attack this disease. Cancer Res; 78(5); 1321-33. ©2018 AACR.

Biogenesis and function of extracellular vesicles in cancer.

Extracellular vesicles (EVs) are heterogeneous multi-signal messengers that support cancer growth and dissemination by mediating the tumor-stroma crosstalk. Exosomes are a subtype of EVs that originate from the limiting membrane of late endosomes, and as such contain information linked to both the intrinsic cell "state" and the extracellular signals cells received from their environment. Resolving the signals affecting exosome biogenesis, cargo sorting and release will increase our understanding of tumorigenesis. In this review we highlight key cell biological processes that couple exosome biogenesis to cargo sorting in cancer cells. Moreover, we discuss how the bidirectional communication between tumor and non-malignant cells affect cancer growth and metastatic behavior.

Long non-coding RNAs within the tumour microenvironment and their role in tumour-stroma cross-talk

Long non-coding RNAs (lncRNAs) are a diverse class of RNA transcripts which have limited protein coding potential. They perform a variety of cellular functions in health, but have also been implicated during malignant transformation.A further theme in recent years is the critical role of the tumour microenvironment and the dynamic interactions between cancer and stromal cells in promoting invasion and disease progression. Whereas the contribution of deregulated lncRNAs within cancer cells has received considerable attention, their significance within the tumour microenvironment is less well understood.The tumour microenvironment consists of cancer-associated stromal cells and structural extracellular components which interact with one another and with the transformed epithelium via complex extracellular signalling pathways. LncRNAs are directly and indirectly involved in tumour/stroma cross-talk and help stimulate a permissive tumour microenvironment which is more conducive for invasive tumour growth. Furthermore, lncRNAs play key roles in determining the phenotype of cancer associated stromal cells and contribute to angiogenesis and immune evasion pathways, extracellular-matrix (ECM) turnover and the response to hypoxic stress.Here we explore the multifaceted roles of lncRNAs within the tumour microenvironment and their putative pathophysiological effects.

Viscoelastic properties of human pancreatic tumors and in vitro constructs to mimic mechanical properties.

Understanding tumor-stroma crosstalk in pancreatic ductal adenocarcinoma (PDAC) is challenged by a lack of stroma-mimicking model systems. To design appropriate models, pancreatic tissue must be characterized with a method capable of evaluating in vitro models as well. Our indentation-based characterization tool quantified the distinct viscoelastic signatures of inflamed resections from pancreatitis, tumors from PDAC, and otherwise normal tissue to inform development of mechanically appropriate engineered tissues and scaffolds. We also made progress toward a 3D in vitro system that recapitulates mechanical properties of tumors. Our in vitro model of stromal cells in collagen and complementary characterization system can be used to investigate mechanisms of cancer-stroma crosstalk in PDAC and to propose and test innovative therapies.

Pancreatic Adenocarcinoma Therapeutic Targets Revealed by Tumor-Stroma Cross-Talk Analyses in Patient-Derived Xenografts

SUMMARYPreclinical models based on patient-derived xenografts have remarkable specificity in distinguishing transformed human tumor cells from non-transformed murine stromal cells computationally. We obtained 29 pancreatic ductal adenocarcinoma (PDAC) xenografts from either resectable or non-resectable patients (surgery and endoscopic ultrasound-guided fine-needle aspirate, respectively). Extensive multiomic profiling revealed two subtypes with distinct clinical outcomes. These subtypes uncovered specific alterations in DNA methylation and transcription as well as in signaling pathways involved in tumor-stromal cross-talk. The analysis of these pathways indicates therapeutic opportunities for targeting both compartments and their interactions. In particular, we show that inhibiting NPC1L1 with Ezetimibe, a clinically available drug, might be an efficient approach for treating pancreatic cancers. These findings uncover the complex and diverse interplay between PDAC tumors and the stroma and demonstrate the pivotal role of xenografts for drug discovery and relevance to PDAC.