Pancreatic stellate cells: the top managers of the pancreatic tumor microenvironment.

Background Stellate pancreatocytes, being cells - producers of stromal components, actively interact with cancer cells, determine the formation of a stromal barrier between the latter and thereby provide tumor chemoresistance. Objective The review is devoted to the analysis of recent data on the role of stellate pancreatocytes in the formation of the stromal microenvironment of pancreatic tumors, molecular mechanisms through which the regulation and realization of stellate cell functions is carried out. Methods Data processing was carried out by the method of complex material analysis. Results. Stellate pancreatocytes (PSC) exhibit phenotypically and functionally two states: inactive and active. PSC activation is carried out by cells of the developing tumor through a variety of molecular mediators. Activation triggers for PSC are Yes-associated protein, TGF-β1, miRNA let-7d, IL-8, MCP1, TGF-β2, IGFBP2, and others. 10 actively expressed genes were identified: TP53, SRC, IL6, JUN, ISG15, CAD, STAT1, OAS3, OAS1, VIM during co-cultivation of a cancer cell line (PCC) with PSC. PSC deactivation is associated with speckle-type mediator POZ (SPOP) acting through nuclear factor-kappaB, transretinoic acid (ATRA). Exhibiting their activity, PSCs express several stem cell markers, α-SMA (α-actin of smooth muscle cells), vimentin, α ITGA 11 (collagen type I receptor), α5 integrin receptor ITGA5 (fibronectin receptor), hyaluronic acid, hyaluronan synthase 2 (HAS2), hyaluronidase 1 (HYAL1), BAG3 , matrix metallopeptidase 2 (MMP2), Nodal protein, miR-1246 and miR-1290, miR-210, CCN2 (connective tissue growth factor), TRPV1, SP and CGRP (Calcitonin gene-related peptide) and many other factors. Сonclusion. Stellate pancreatocytes, being producers of the interacinar stroma, are activated by various factors (TNF-α, IL-6, MCP-1, ATP, and HMGB1, etc.), including factors produced by tumor cells of the pancreas, and act as regulators of proliferation, migration, and suppression apoptosis of the latter. An increase in the expression of α ITGA 11 (type I collagen receptor), α5 integrin receptor ITGA5 (fibronectin receptor), metallopeptidases, Nodal protein, miR-1246, miR-1290, and miR-210 is observed in tumor tissue, that indicates the activation of these cells. The maintenance of the active state of PSC is provided by tumor cells, for which stellate pancreatocytes are partners in the progression of the neoplastic process. Further study of the mechanisms of interaction in the PSC-tumor cell system creates the prospect of revealing levers of influence on the pathogenesis of pancreatic tumors.

CXCL12 in Pancreatic Cancer: Its Function and Potential as a Therapeutic Drug Target

Pancreatic ductal adenocarcinoma (PDAC) is a disease with limited therapeutic options and dismal long-term survival. The unique tumor environment of PDAC, consisting of desmoplastic stroma, immune suppressive cells, and activated fibroblasts, contributes to its resistance to therapy. Activated fibroblasts (cancer-associated fibroblasts and pancreatic stellate cells) secrete chemokines and growth factors that support PDAC growth, spread, chemoresistance, and immune evasion. In this review, we focus on one such chemokine, CXCL12, secreted by the cancer-associated fibroblasts and discuss its contribution to several of the classical hallmarks of PDAC and other tumors. We review the various therapeutic approaches in development to target CXCL12 signaling in PDAC. Finally, we propose an unconventional use of tipifarnib, a farnesyl transferase inhibitor, to inhibit CXCL12 production in PDAC.

Signaling pathways involved in pancreatic stellate cells activity and interaction with pancreatic cancer cells

Background. The activation, proliferation and migration capabilities of stellate pancreatocytes are guaranteed by a number of signaling molecular mechanisms that support the interaction of tumor cells with the PSC and determine the neoplastic process. Objective The review is a continuation of aт articles series devoted to the modern understanding of the role and functions of stellate pancreatocytes, namely, their involvement in interaction with cancer cells and signaling molecular pathways that provide synergism of the stellate pancreatocyte-cancer cell system. Methods. Data processing was carried out by the method of complex material analysis. Results. The Нedgehog signaling pathway provides interaction between PSC and tumor cells, which involves the leading mediator of this pathway - sHH (sonic hedgehog), the overexpression of which is recorded in the tumor tissue of the pancreas and ensures the formation of the tumor stroma. Stellate pancreatocytes also trigger the HGF / c-Met / survivin signaling pathway for invasion and metastasis. The activation of the PSCs themselves may be mediated by serotonin via the RhoA / ROCK signaling pathway. While the proliferation and migration of these cells, activated by alcohol, HNE (human neutrophil elastase), PDGF, IL-33 PSC are regulated by the MAP kinase and PI3K pathways. The Wnt signaling pathway promotes collagen accumulation. Through the AMPK / mTOR pathway, factor FTY720 induces apoptosis and inhibits the autophagy of stellate pancreatocytes. The interaction of PSC and tumor cells is also mediated through Notch and TGF-β, and through the Hippo signaling pathway with the participation of YAP / TAZ factors, it is possible to suppress the fibrotic activity of PSC. The interaction of stellate pancreatocytes and tumor cells is reflected in a direct correlation between a decrease in autophagy and apoptosis of stellate pancreatocytes and suppression of invasion and migration of tumor cells. This interaction can be mediated by ERK1 / 2 kinase. Among the factors secreted by tumor cells and causing PSC activation are: growth factor β1 (TGF-β1), PAI-1 protein, translation initiation factor 4E (eIF4E), sHH (involving PSC in pain deployment), Exo-Pan and Exo-Mia exosomes (engaging PSCs in carcinogenesis). Deactivation is mediated by colony stimulating factor 1 (CSF1R, cytokine). In turn, stellate pancreatocytes secrete the chemokine CXCL1, which stimulates the migration and invasion of tumor cells, exosomes with multiple miRNAs, which stimulate the proliferation and migration of cancer cells. Сonclusion. The activation of stellate pancreatocytes, which is necessary for the implementation of their fibrotic functions, is mediated through the RhoA / ROCK signaling pathway via serotonin. The Hippo pathway (activation) and AMPK / mTOR (suppression of autophagy and activation of apoptosis) are also involved in the regulation of the activity of stellate pancreatocytes. The interaction between the tumor cell and stellate pancreatocyte occurs through the Hedgehog, Notch, and TGF-β signaling pathways; regulation of invasion and metastasis of cancer cells provides the HGF / c-Met / survivin signaling pathway.

Heterogeneous Pancreatic Stellate Cells Are Powerful Contributors to the Malignant Progression of Pancreatic Cancer

Pancreatic cancer is associated with highly malignant tumors and poor prognosis due to strong therapeutic resistance. Accumulating evidence shows that activated pancreatic stellate cells (PSC) play an important role in the malignant progression of pancreatic cancer. In recent years, the rapid development of single-cell sequencing technology has facilitated the analysis of PSC population heterogeneity, allowing for the elucidation of the relationship between different subsets of cells with tumor development and therapeutic resistance. Researchers have identified two spatially separated, functionally complementary, and reversible subtypes, namely myofibroblastic and inflammatory PSC. Myofibroblastic PSC produce large amounts of pro-fibroproliferative collagen fibers, whereas inflammatory PSC express large amounts of inflammatory cytokines. These distinct cell subtypes cooperate to create a microenvironment suitable for cancer cell survival. Therefore, further understanding of the differentiation of PSC and their distinct functions will provide insight into more effective treatment options for pancreatic cancer patients.

Reversal of pancreatic desmoplasia by a tumour stroma-targeted nitric oxide nanogel overcomes TRAIL resistance in pancreatic tumours

ObjectiveStromal barriers, such as the abundant desmoplastic stroma that is characteristic of pancreatic ductal adenocarcinoma (PDAC), can block the delivery and decrease the tumour-penetrating ability of therapeutics such as tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), which can selectively induce cancer cell apoptosis. This study aimed to develop a TRAIL-based nanotherapy that not only eliminated the extracellular matrix barrier to increase TRAIL delivery into tumours but also blocked antiapoptotic mechanisms to overcome TRAIL resistance in PDAC.DesignNitric oxide (NO) plays a role in preventing tissue desmoplasia and could thus be delivered to disrupt the stromal barrier and improve TRAIL delivery in PDAC. We applied an in vitro–in vivo combinatorial phage display technique to identify novel peptide ligands to target the desmoplastic stroma in both murine and human orthotopic PDAC. We then constructed a stroma-targeted nanogel modified with phage display-identified tumour stroma-targeting peptides to co-deliver NO and TRAIL to PDAC and examined the anticancer effect in three-dimensional spheroid cultures in vitro and in orthotopic PDAC models in vivo.ResultsThe delivery of NO to the PDAC tumour stroma resulted in reprogramming of activated pancreatic stellate cells, alleviation of tumour desmoplasia and downregulation of antiapoptotic BCL-2 protein expression, thereby facilitating tumour penetration by TRAIL and substantially enhancing the antitumour efficacy of TRAIL therapy.ConclusionThe co-delivery of TRAIL and NO by a stroma-targeted nanogel that remodels the fibrotic tumour microenvironment and suppresses tumour growth has the potential to be translated into a safe and promising treatment for PDAC.

Alpha Smooth Muscle Actin (αSMA) Immunohistochemistry Use in the Differentiation of Pancreatic Cancer from Chronic Pancreatitis

Aim: Fibrosis is observed both in pancreatic cancer (PDAC) and chronic pancreatitis (CP). The main cells involved in fibrosis are pancreatic stellate cells (PSCs), which activate alpha smooth muscle actin (αSMA), which is considered to be the best-known fibrosis marker. The aim of the study was to evaluate the expression of the αSMA in patients with PDAC and CP as the possible differentiation marker. Methods: We enrolled 114 patients undergoing pancreatic resection: 83 with PDAC and 31 with CP. Normal fragments of resected specimen from 21 patients represented the control tissue. The immunoexpressions of αSMA were detected in tissue specimens with immunohistochemistry (Abcam antibodies, GB). Results: Mean cytoplasmatic expression of αSMA protein in PDAC stromal cells was significantly higher compared to CP: 2.42 ± 0.37 vs 1.95 ± 0.45 (p < 0.01) and control group 0.61 ± 0.45 (p < 0.01). Strong immunoexpression of the αSMA protein was found in the vast majority (80.7%) of patients with PDAC, in about half (58%) of patients with CP, and not at all in healthy tissue. The expression of αSMA of different intensity was found in all patients with PDAC and CP, while in healthy tissue was minimal or absent. In PDAC patients, αSMA expression was significantly higher in tumors of diameter higher than 3 cm compared to smaller ones (p = 0.017). Conclusions: Presented findings confirm the significant role of fibrosis in both PDAC and CP; however, they do not confirm the role of αSMA as a marker of differentiation.

O-P03 A composite polymeric nanoparticle as a sensitiser for sonodynamic therapy (SDT)-based treatment of pancreatic cancer

Background Pancreatic cancer remains one of the most recalcitrant forms of cancer with poor prognosis and limited treatment options. SDT is a novel, targeted approach to the treatment of solid tumours. Based on the generation of cytotoxic reactive oxygen species (ROS) following the exposure of a sonosensitiser to ultrasound, the approach is designed to extracorporeally target less accessible lesions. Here we describe the production of a poly(lactic-co-glycolic acid) (PLGA), polyethyleneimine (PEI), Rose Bengal (RB) and indocyanine green (ICG) containing composite nanoparticles and describe their use in SDT-mediated treatment of pancreatic cancer using both in vitro and in vivo target models. Methods Nanoparticles were prepared using an oil in water emulsion and solvent diffusion-based approach. These were designated RB-ICGNP. In vitro SDT treatment consisted of exposing BxPC3 (human PDAC cells), T110029 (murine PDAC cells) or hPSC (immortalised human pancreatic stellate cells) to RB-ICGNP and subsequently treating with ultrasound for 30 s at a frequency of 1 MHz, a power density of 3.0 W/cm2 (SATP) using a duty cycle of 50% at a pulse repetition frequency of 100 Hz. For in vivo studies, BxPC3 (xenograft) and T110029 (syngeneic) tumours were treated with a power density of 3.5 W/cm2 ultrasound for 3.5 min. Results Conclusions Using in vitro and in vivo (human xenograft and murine syngeneic) models of pancreatic cancer, RB-ICGNP composite nanoparticles may be employed as a sensitiser for SDT-based treatment of pancreatic cancer. Since pancreatic stellate cells were more sensitive to SDT, the latter may have an impact on tumour stroma. Staining of residual tumour tissues from SDT-treated animals for connective tissue (stroma) confirmed the latter. Since tumour stroma presents a significant challenge to treatment of pancreatic cancer and represents a negative prognostic marker, the impact delivered by SDT may be exploited to potentiate alternative therapeutic approaches.

Anti-Cancer Activity Profiling of Chemotherapeutic Agents in 3D Co-Cultures of Pancreatic Tumor Spheroids with Cancer-Associated Fibroblasts and Macrophages

Activated pancreatic stellate cells (aPSCs) and M2 macrophages modulate tumor progression and therapeutic efficacy in pancreatic ductal adenocarcinoma (PDAC) via epithelial-mesenchymal transition (EMT). Here, our aim was to analyze the anti-invasion effects of anti-cancer agents where EMT-inducing cancer-stroma interaction occurs under three-dimensional (3D) culture conditions. We used microfluidic channel chips to co-culture pancreatic tumor spheroids (TSs) with aPSCs and THP-1-derived M2 macrophages (M2 THP-1 cells) embedded in type I collagen. Under stromal cell co-culture conditions, PANC-1 TSs displayed elevated expression of EMT-related proteins and increased invasion and migration. When PANC-1 TSs were exposed to gemcitabine, 5-fluorouracil, oxaliplatin, or paclitaxel, 30–50% cells were found unaffected, with no significant changes in the dose-response profiles under stromal cell co-culture conditions. This indicated intrinsic resistance to these drugs and no further induction of drug resistance by stromal cells. Paclitaxel had a significant anti-invasion effect; in contrast, oxaliplatin did not show such effect despite its specific cytotoxicity in M2 THP-1 cells. Overall, our findings demonstrate that the TS-stroma co-culture model of PDAC is useful for activity profiling of anti-cancer agents against cancer and stromal cells, and analyzing the relationship between anti-stromal activity and anti-invasion effects.

Exosomal lncRNA UCA1 Derived From Pancreatic Stellate Cells Promotes Gemcitabine Resistance in Pancreatic Cancer via the SOCS3/EZH2 Axis

ObjectivePancreatic cancer is associated with poor prognosis and dismal survival rates. This study aims to investigate roles of lncRNA UCA1-loaded exosomes secreted by pancreatic stellate cells (PSCs) in Gemcitabine (Gem) resistance of pancreatic cancer under hypoxia, which involves the methylation of SOCS3 and EZH2 recruitment.MethodsThe exosomes were isolated from PSCs and hypoxic PSCs (HPSCs), and co-cultured with pancreatic cancer cells transduced with manipulated lncRNA UCA1, EZH2, and SOCS3. The interaction among lncRNA UCA1, EZH2, and SOCS3 was characterized by RIP and ChIP assays. Next, MTT assay, flow cytometry and TUNEL staining and Transwell assay were used to detect cell viability, apoptosis, invasion, and migration. Gem-resistant pancreatic cancer cell line (GemMIA-R3) was established, which was applied in a mouse xenograft model of pancreatic cancer, with MTT assay to determine Gem sensitivity.ResultsLncRNA UCA1 was highly expressed, while SOCS3 was poorly expressed in pancreatic cancer tissues. Hypoxia induced activation of PSCs and promoted release of exosomes. LncRNA UCA1 delivered by hypoxic PSC-derived exosomes (HPSC-EXO) regulated histone methylation level in SOCS3 gene region through recruitment of EZH2. In vitro and in vivo experimental results confirmed that lncRNA UCA1-loaded HPSC-EXO promoted malignant phenotypes, inhibited apoptosis, and promoted Gem resistance of pancreatic cancer cells as well as tumorigenesis in mice.ConclusionUnder hypoxic conditions, exosomes secreted by hypoxia-induced PSCs deliver lncRNA UCA1 into pancreatic cancer cells, where lncRNA UCA1 recruits EZH2 and regulates histone methylation level in SOCS3 gene region, thereby augmenting pancreatic cancer resistance to Gem.