Tumor Microenvironment Of Pancreatic Cancer Research Articles

Abstract 2795: An investigation to identify the phylogeny of bacterial communities in the pancreatic cancer microbiome by 16SrDNA sequencing and bioinformatic analysis

Abstract The microbiome refers to the diverse community of microorganisms, including bacteria, viruses, fungi, and other microbes, that inhabit various parts of the human body, such as the skin, mouth, gut, and other mucosal surfaces. The role of the microbiome in cancer is a complex and evolving area of research. While much is still being learned, there is evidence suggesting that the microbiome can influence cancer development and progression in several ways. Some bacteria within the microbiome can produce substances that may be either carcinogenic or protective against cancer. For instance, the conversion of certain dietary components by gut bacteria can produce metabolites that may either promote or inhibit cancer development. Different cancers may be associated with specific alterations in the microbiome, for example, the gut microbiome has been extensively studied in relation to colorectal cancer, with certain bacterial species potentially contributing to the development of this cancer. However, the role of microbiome in Pancreatic cancer is still not extensively studied, henceforth, we did a preliminary study to identify novel bacterial communities around pancreatic cancer microbiome by 16SrDNA sequencing in human pancreatic cancer xenograft model mice. Isolating total genomic DNA from the pancreatic model mice feces, 16SrDNA PCR was done using specific primers and the amplicon obtained as PCR product was confirmed by standard DNA gel electrophoresis with a 1 kb standard ladder to be 1.5kb in size universal for all bacterial 16SrDNA. The amplicon was then sent for Next Generation Sequencing at Zymo Research Corporation (CA). The resultant DNA sequences were analyzed by bioinformatics studies and their phylogeny identified by comparing with 16SrDNA data base. Differential abundance of the bacteria’s of the genera Lachnoclostridium, Robinsoniella, Alistipes, Akkermansia and Lactobacillus were observed analyzing the data along with other bacterial communities. We are currently continuing the project to identify more bacterial communities of significance in the pancreatic cancer microbiome and investigating the role and significance of these bacterial communities in pancreatic cancer tumor microenvironment. Acknowledgement This study was done by a joint collaboration between scientists and students of Elizabeth City State University (ECSU) campus of the University of North Carolina Systems and Mayo Clinic, Jacksonville. This research is supported by the NIH-NIGMS grant#T34GM100831-10 to Dr. H. Banerjee and a University of North Carolina General Administration Grant to Dr. Colby Hunter at ECSU. Citation Format: Hirendra N. Banerjee, Colby Hunter, Narendra Banerjee, Karrington Perry, Khadimou Dia, Anasua Banerjee, Santanu Bhattacharya, Hari Krishnareddy Rachamala, Enfang Wang, Shamit Dutta. An investigation to identify the phylogeny of bacterial communities in the pancreatic cancer microbiome by 16SrDNA sequencing and bioinformatic analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2795.

Exploration of immune cell heterogeneity by single-cell RNA sequencing and identification of secretory leukocyte protease inhibitor as an oncogene in pancreatic cancer.

Clinical outcomes remain unsatisfactory in patients with pancreatic cancer (PAC). In this study, through single-cell sequencing, we identified eight cell subpopulations in the tumor microenvironment (TME). Redimensional clustering of epithelial cells, myeloid cells, and cancer-associated fibroblasts (CAFs) revealed heterogeneity in the TME of PAC. Intercellular communication analysis showed strong direct interactions between matrix CAFs, inflammatory CAFs, and epithelial cells. Additionally, we found that the SPP1-associated pathway was activated in monocytes, whereas the vascular endothelial growth factor-associated pathway was activated in epithelial cells. These results improve the understanding of the TME of pancreatic cancer and provide a foundation for further studies on intratumoral heterogeneity. In addition, differentially expressed gene secretory leukocyte protease inhibitor (SLPI) was identified in pancreatic cancer, and functional experiments showed that SLPI had a strong impact on cell viability and apoptosis, which offers a potential therapy target for pancreatic cancer.

Pancreatic cancer tumor microenvironment is a major therapeutic barrier and target.

Pancreatic Ductal Adenocarcinoma (PDAC) is projected to become the 2nd leading cause of cancer-related deaths in the United States. Limitations in early detection and treatment barriers contribute to the lack of substantial success in the treatment of this challenging-to-treat malignancy. Desmoplasia is the hallmark of PDAC microenvironment that creates a physical and immunologic barrier. Stromal support cells and immunomodulatory cells face aberrant signaling by pancreatic cancer cells that shifts the complex balance of proper repair mechanisms into a state of dysregulation. The product of this dysregulation is the desmoplastic environment that encases the malignant cells leading to a dense, hypoxic environment that promotes further tumorigenesis, provides innate systemic resistance, and suppresses anti-tumor immune invasion. This desmoplastic environment combined with the immunoregulatory events that allow it to persist serve as the primary focus of this review. The physical barrier and immune counterbalance in the tumor microenvironment (TME) make PDAC an immunologically cold tumor. To convert PDAC into an immunologically hot tumor, tumor microenvironment could be considered alongside the tumor cells. We discuss the complex network of microenvironment molecular and cellular composition and explore how they can be targeted to overcome immuno-therapeutic challenges.

Integrative analysis of spatial and single-cell transcriptome data from human pancreatic cancer reveals an intermediate cancer cell population associated with poor prognosis

BackgroundRecent studies using single-cell transcriptomic analysis have reported several distinct clusters of neoplastic epithelial cells and cancer-associated fibroblasts in the pancreatic cancer tumor microenvironment. However, their molecular characteristics and biological significance have not been clearly elucidated due to intra- and inter-tumoral heterogeneity.MethodsWe performed single-cell RNA sequencing using enriched non-immune cell populations from 17 pancreatic tumor tissues (16 pancreatic cancer and one high-grade dysplasia) and generated paired spatial transcriptomic data from seven patient samples.ResultsWe identified five distinct functional subclusters of pancreatic cancer cells and six distinct cancer-associated fibroblast subclusters. We deeply profiled their characteristics, and we found that these subclusters successfully deconvoluted most of the features suggested in bulk transcriptome analysis of pancreatic cancer. Among those subclusters, we identified a novel cancer cell subcluster, Ep_VGLL1, showing intermediate characteristics between the extremities of basal-like and classical dichotomy, despite its prognostic value. Molecular features of Ep_VGLL1 suggest its transitional properties between basal-like and classical subtypes, which is supported by spatial transcriptomic data.ConclusionsThis integrative analysis not only provides a comprehensive landscape of pancreatic cancer and fibroblast population, but also suggests a novel insight to the dynamic states of pancreatic cancer cells and unveils potential therapeutic targets.Graphical

Abstract B044: Targeting integrin alpha V beta 3 remodels the tumor microenvironment in pancreatic cancer

Abstract In pancreatic ductal adenocarcinoma (PDAC) the tumor microenvironment (TME) plays a crucial role in therapy resistance, metastasis, and recurrence. ProAgio is a novel therapeutic cytotoxin rationally designed to bind outside the RGD ligand pocket of the alphaV-beta3 integrin pair and then kill cells expressing this target. Pre-clinical studies demonstrated the safety and anti-tumor efficacy of ProAgio in animal models, and ProAgio is currently being tested in a Phase I clinical trial. The effect of ProAgio on TME cellular components has not been closely examined. We hypothesized that ProAgio remodels the PDAC TME to decrease stromal density and local immunosuppression by killing stromal cells thought to express the integrin pair, such as cancer associated fibroblasts (CAFs), proliferating endothelial cells, and tumor associated macrophages (TAMs). To identify potential cellular targets of ProAgio in the PDAC TME, we re-analyzed publicly available single cell RNA-seq datasets of human and mouse PDAC samples. We assessed integrin co-expression using flow cytometry, performed immunophenotyping and histopathological analysis to identify TME cellular and structural alterations induced by ProAgio. Integrins αV and β3 were both expressed at the RNA level in TAMs, myeloid cells, lymphocytes (T, B and NK), endothelial cells and CAFs. In the autochthonous KPC mouse model, we confirmed that granulocytes, macrophages, monocytes, CD4+ and CD8+T cells co-expressed integrin αVβ3 at the protein level. Amongst CAFs, inflammatory CAFs (iCAFs) had the highest percentage of cells co-expressing αV and β3 integrins. No anti-tumor effect was observed after 14 days of ProAgio treatment in a syngeneic KPC-derived PDAC orthotopic model, however, in the KPC autochthonous model the same treatment retarded tumor growth within 1 week. ProAgio treated autochthonous tumors displayed no changes in immune components or CAF subsets, but increased collagen area was observed. In addition, ProAgio treatment resulted in higher blood vessel area while integrin β3 protein levels remained stable. In conclusion, short-course ProAgio remodels the TME and delays tumor growth in an autochthonous PDAC model with mature stromal components, but does not deplete CAFs, TAMs or collagen area. Future studies will seek to refine our understanding of the cell subtypes affected by more prolonged ProAgio treatment and to determine the cellular and inflammatory mediators responsible for these changes. Citation Format: Mayrel Palestino Dominguez, Philip Homan, Xianyu Zhang, Sandra Navas Reyes, Theresa Guerin, Laura Bassel, Liu Zhi-ren, Serguei Kozlov, Christine Alewine. Targeting integrin alpha V beta 3 remodels the tumor microenvironment in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B044.

Abstract B096: Acquired resistance to KRAS inhibition modulates the pancreatic cancer tumor microenvironment

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with dismal patient outcomes. Acquired resistance to chemotherapeutics is a major barrier to successful pancreatic cancer treatment. MRTX-1133 is a potent, selective KRAS G12D inhibitor that is in early-phase clinical trials. While initially effective, clinical experience with KRAS G12C inhibitors has shown tumors rapidly acquire therapeutic resistance. The tumor microenvironment (TME) plays a pivotal role in resistance development by activating prosurvival pathways, promoting epithelial-mesenchymal transition (EMT) and stemness, and inhibiting apoptosis. In this study, we sought to understand changes in the PDAC TME associated with acquired resistance to KRAS G12D inhibition. Methods: In order to investigate resistance to KRAS G12D inhibition in PDAC, we developed various mouse and human MRTX-1133 resistant (MRTXR) cell models (FC1199, FC1242, FC1245, and SUIT2). Intriguingly, these models also displayed resistance to several pan-RAS(ON) inhibitors. We utilized flow cytometry analysis to investigate the dynamic changes occurring in the TME following resistance to MRTX-1133, and we employed cytokine array and RNA-seq analyses to elucidate the impact of cancer cells on gene and protein expression of TME cells. Results: A comparative analysis between parental PDAC cells and MRTXR tumors revealed significant alterations within the TME. We found a significant decrease (p=0.013, p=0.045, respectively) in the number of inactivated and naïve CD8 T cells (CD8+/CD69+ and CD44-/CD62L+ cells) in MRTXR tumors. We also observed an upregulation of CXCL1, CCL20, and CXCL2 secretion in MRTXR cells compared to parental cells. Conclusions: Pancreatic cancer cells with acquired resistance to KRAS inhibitors modulate their tumor microenvironment uniquely. Ongoing studies aim to identify the critical pathways responsible for these alterations and to develop alternative treatment strategies for KRAS therapy-resistant tumors. Citation Format: Kevin Christian Montecillo Gulay, Jay Patel, Isabella Ng, Tatiana Hurtado de Mendoza, Herve Tiriac, Andrew Lowy. Acquired resistance to KRAS inhibition modulates the pancreatic cancer tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B096.

High ANO1 expression is a prognostic factor and correlated with an immunosuppressive tumor microenvironment in pancreatic cancer.

Aminooctylamine (ANO1) plays an oncogenic role in various cancers. However. its role in pancreatic cancer (PC) has rarely been studied. This study investigated the prognostic value of ANO1 and its correlation with the tumor microenvironment (TME) in PC. Consecutive patients with PC (n = 119) were enrolled. The expression of ANO1 in cancer cells, the expression of fibroblast activation protein (FAP) and alpha smooth muscle actin in cancer-associated fibroblasts (CAFs), and the numbers of CD8- and FOXP3-positive tumor-infiltrating lymphocytes (TILs) were evaluated using immunohistochemistry. The prognostic value of ANO1 and its correlation with CAF subgroups and TILs were analyzed. The possible mechanism of ANO1 in the TME of PC was predicted using the the Cancer Genome Atlas (TCGA) dataset. The expression of AN01 was correlated with overall survival (OS) and disease-free survival. Multi-factor analysis showed that high ANO1 expression was an independent adverse prognostic factor for OS (hazard ratio, 4.137; P = 0.001). ANO1 expression was positively correlated with the expression of FAP in CAFs (P < 0.001) and negatively correlated with the number of CD8-positive TILs (P = 0.005), which was also validated by bioinformatics analysis in the TCGA dataset. Moreover, bioinformatic analysis of the TCGA dataset revealed that ANO1 may induce an immunosuppressive tumor microenvironment in pancreatic cancer in a paracrine manner. ANO1 is a prognostic factor in patients with PC after radical resection. ANO1 may induce an immunosuppressive tumor microenvironment in PC in a paracrine manner, suggesting that ANO1 may be a novel therapeutic target.

Current Status and Perspectives of Pancreatic Cancer Tumor Microenvironment and Therapy

Current Status and Perspectives of Pancreatic Cancer Tumor Microenvironment and Therapy

Bioinformatics-based analysis of the relationship between disulfidptosis and prognosis and treatment response in pancreatic cancer

Tumor formation is closely associated with disulfidptosis, a new form of cell death induced by disulfide stress-induced. The exact mechanism of action of disulfidptosis in pancreatic cancer (PCa) is not clear. This study analyzed the impact of disulfidptosis-related genes (DRGs) on the prognosis of PCa and identified clusters of DRGs, and based on this, a risk score (RS) signature was developed to assess the impact of RS on the prognosis, immune and chemotherapeutic response of PCa patients. Based on transcriptomic data and clinical information from PCa tissue and normal pancreatic tissue samples obtained from the TCGA and GTEx databases, differentially expressed and differentially surviving DRGs in PCa were identified from among 15 DRGs. Two DRGs clusters were identified by consensus clustering by merging the PCa samples in the GSE183795 dataset. Analysis of DRGs clusters about the PCa tumor microenvironment and differential analysis to obtain differential genes between the two DRG clusters. Patients were then randomized into the training and testing sets, and a prognostic prediction signature associated with disulfidptosis was constructed in the training set. Then all samples were divided into high-disulfidptosis-risk (HDR) and low-disulfidptosis-risk (LDR) subgroups based on the RS calculated from the signature. The predictive efficacy of the signature was assessed by survival analysis, nomograms, correlation analysis of clinicopathological characteristics, and the receiver operating characteristic (ROC) curves. To assess differences between different risk subgroups in immune cell infiltration, expression of immune checkpoint molecules, somatic gene mutations, and effectiveness of immunotherapy and chemotherapy. The GSE57495 dataset was used as external validation, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression levels of DRGs. A total of 12 DRGs with differential expression and prognosis in PCa were identified, based on which a risk-prognosis signature containing five differentially expressed genes (DEGs) was developed. The signature was a good predictor and an independent risk factor. The nomogram and calibration curve shows the signature's excellent clinical applicability. Functional enrichment analysis showed that RS was associated with tumor and immune-related pathways. RS was strongly associated with the tumor microenvironment, and analysis of response to immunotherapy and chemotherapy suggests that the signature can be used to assess the sensitivity of treatments. External validation further demonstrated the model's efficacy in predicting the prognosis of PCa patients, with RT-qPCR and immunohistochemical maps visualizing the expression of each gene in PCa cell lines and the tissue. Our study is the first to apply the subtyping model of disulfidptosis to PCa and construct a signature based on the disulfidptosis subtype, which can provide an accurate assessment of prognosis, immunotherapy, and chemotherapy response in PCa patients, providing new targets and directions for the prognosis and treatment of PCa.

CAFs Homologous Biomimetic Liposome Bearing BET Inhibitor and Pirfenidone Synergistically Promoting Antitumor Efficacy in Pancreatic Ductal Adenocarcinoma.

BRD4 is a member of the BET protein family involved in chromatin remodeling and transcriptional regulation. Several BET inhibitors (BETi) have entered clinical trials, demonstrating potential in inducing cancer cell apoptosis and tumor regression. However, resistance to BETi is common in solid tumors. In pancreatic cancer, it is found that cancer-associated fibroblasts (CAFs) in the tumor microenvironment reduce the BET inhibitor JQ1 sensitivity by inducing BRD4 expression. Moreover, CAFs play a crucial role in the formation of a dense stromal barrier. Therefore, targeting CAFs in the tumor microenvironment of pancreatic cancer not only enhances cancer cells sensitivity to JQ1 but also increases drug perfusion and improves oxygen supply, thus reducing glycolysis and limiting energy supply. To address this challenge, a homologous targeting mechanism utilizing activated fibroblast membrane-coated liposomes is proposed for specific drug precise target to CAFs-rich pancreatic cancer. Additionally, TAT peptides enable liposomes penetration, delivering PFD for targeted anti-fibrotic therapy, reducing extracellular matrix generation and glycolysis, and enhancing JQ1 delivery and sensitivity. In conclusion, the findings indicate the tremendous potential of this CAFs-targeting liposomal delivery system in pancreatic cancer.

The Tautomerase Activity of Tumor Exosomal MIF Promotes Pancreatic Cancer Progression by Modulating MDSC Differentiation.

Pancreatic cancer is a deadly disease that is largely resistant to immunotherapy, in part because of the accumulation of immunosuppressive cells in the tumor microenvironment (TME). Much evidence suggests that tumor-derived exosomes (TDE) contribute to the immunosuppressive activity mediated by myeloid-derived suppressor cells (MDSC) within the pancreatic cancer TME. However, the underlying mechanisms remain elusive. Herein, we report that macrophage migration inhibitory factor (MIF) in TDEs has a key role in inducing MDSC formation in pancreatic cancer. We identified MIF in both human and murine pancreatic cancer-derived exosomes. Upon specific shRNA-mediated knockdown of MIF, the ability of pancreatic cancer-derived exosomes to promote MDSC differentiation was abrogated. This phenotype was rescued by reexpression of the wild-type form of MIF rather than a tautomerase-null mutant or a thiol-protein oxidoreductase-null mutant, indicating that both MIF enzyme activity sites play a role in exosome-induced MDSC formation in pancreatic cancer. RNA sequencing data indicated that MIF tautomerase regulated the expression of genes required for MDSC differentiation, recruitment, and activation. We therefore developed a MIF tautomerase inhibitor, IPG1576. The inhibitor effectively inhibited exosome-induced MDSC differentiation in vitro and reduced tumor growth in an orthotopic pancreatic cancer model, which was associated with decreased numbers of MDSCs and increased infiltration of CD8+ T cells in the TME. Collectively, our findings highlight a pivotal role for MIF in exosome-induced MDSC differentiation in pancreatic cancer and underscore the potential of MIF tautomerase inhibitors to reverse the immunosuppressive pancreatic cancer microenvironment, thereby augmenting anticancer immune responses.

Overexpression of the adhesion signaling pathway is linked to short-term survival in pancreatic ductal adenocarcinoma

Background and objectivePancreatic ductal adenocarcinoma (PDAC) is known for its unfavorable prognosis. Gaining insights into the molecular mechanisms that contribute to its progression is crucial for developing effective therapies. In this study, our objective was to investigate the molecular pathways associated with short-term survival in patients with PDAC. MethodsImmune profiles were analyzed from both long-term survivors (n = 10) and short-term survivors (n = 10) after surgical resection. Pathway scores were calculated to compare the two groups. ResultsThe “Adhesion” pathway emerged as the most significant pathway, exhibiting a notably higher score in the samples of short-term survivors (P < 0.009). Within this pathway, significant findings were observed in genes related to integrins and CEACAM. ConclusionThe role of integrins in the tumor microenvironment of pancreatic cancer is of utmost importance, as they are found to be overexpressed in short-term survivors. These findings provide valuable insights into the underlying biology of PDAC and have potential implications for the development of therapeutic strategies.

1647P Cancer-associated endocrine cell: A novel component of tumor microenvironment in pancreatic cancer

1647P Cancer-associated endocrine cell: A novel component of tumor microenvironment in pancreatic cancer

An integrated overview of the immunosuppression features in the tumor microenvironment of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies. It is characterized by a complex and immunosuppressive tumor microenvironment (TME), which is primarily composed of tumor cells, stromal cells, immune cells, and acellular components. The cross-interactions and -regulations among various cell types in the TME have been recognized to profoundly shape the immunosuppression features that meaningfully affect PDAC biology and treatment outcomes. In this review, we first summarize five cellular composition modules by integrating the cellular (sub)types, phenotypes, and functions in PDAC TME. Then we discuss an integrated overview of the cross-module regulations as a determinant of the immunosuppressive TME in PDAC. We also briefly highlight TME-targeted strategies that potentially improve PDAC therapy.

Unveiling the role of regulatory T cells in the tumor microenvironment of pancreatic cancer through single-cell transcriptomics and in vitro experiments.

In order to investigate the impact of Treg cell infiltration on the immune response against pancreatic cancer within the tumor microenvironment (TME), and identify crucial mRNA markers associated with Treg cells in pancreatic cancer, our study aims to delve into the role of Treg cells in the anti-tumor immune response of pancreatic cancer. The ordinary transcriptome data for this study was sourced from the GEO and TCGA databases. It was analyzed using single-cell sequencing analysis and machine learning. To assess the infiltration level of Treg cells in pancreatic cancer tissues, we employed the CIBERSORT method. The identification of genes most closely associated with Treg cells was accomplished through the implementation of weighted gene co-expression network analysis (WGCNA). Our analysis of single-cell sequencing data involved various quality control methods, followed by annotation and advanced analyses such as cell trajectory analysis and cell communication analysis to elucidate the role of Treg cells within the pancreatic cancer microenvironment. Additionally, we categorized the Treg cells into two subsets: Treg1 associated with favorable prognosis, and Treg2 associated with poor prognosis, based on the enrichment scores of the key genes. Employing the hdWGCNA method, we analyzed these two subsets to identify the critical signaling pathways governing their mutual transformation. Finally, we conducted PCR and immunofluorescence staining in vitro to validate the identified key genes. Based on the results of immune infiltration analysis, we observed significant infiltration of Treg cells in the pancreatic cancer microenvironment. Subsequently, utilizing the WGCNA and machine learning algorithms, we ultimately identified four Treg cell-related genes (TRGs), among which four genes exhibited significant correlations with the occurrence and progression of pancreatic cancer. Among them, CASP4, TOB1, and CLEC2B were associated with poorer prognosis in pancreatic cancer patients, while FYN showed a correlation with better prognosis. Notably, significant differences were found in the HIF-1 signaling pathway between Treg1 and Treg2 cells identified by the four genes. These conclusions were further validated through in vitro experiments. Treg cells played a crucial role in the pancreatic cancer microenvironment, and their presence held a dual significance. Recognizing this characteristic was vital for understanding the limitations of Treg cell-targeted therapies. CASP4, FYN, TOB1, and CLEC2B exhibited close associations with infiltrating Treg cells in pancreatic cancer, suggesting their involvement in Treg cell functions. Further investigation was warranted to uncover the mechanisms underlying these associations. Notably, the HIF-1 signaling pathway emerged as a significant pathway contributing to the duality of Treg cells. Targeting this pathway could potentially revolutionize the existing treatment approaches for pancreatic cancer.

Lorazepam Stimulates IL6 Production and Is Associated with Poor Survival Outcomes in Pancreatic Cancer.

This research investigates the association between benzodiazepines (BZD) and cancer patient survival outcomes, the pancreatic cancer tumor microenvironment, and cancer-associated fibroblast (CAF) signaling. Multivariate Cox regression modeling was used to retrospectively measure associations between Roswell Park cancer patient survival outcomes and BZD prescription records. IHC, H&E, Masson's trichrome, RNAscope, and RNA sequencing were used to evaluate the impact of lorazepam (LOR) on the murine PDAC tumor microenvironment. ELISA and qPCR were used to determine the impact of BZDs on IL6 expression or secretion by human-immortalized pancreatic CAFs. PRESTO-Tango assays, reanalysis of PDAC single-cell sequencing/TCGA data sets, and GPR68 CRISPRi knockdown CAFs were used to determine the impact of BZDs on GPR68 signaling. LOR is associated with worse progression-free survival (PFS), whereas alprazolam (ALP) is associated with improved PFS, in pancreatic cancer patients receiving chemotherapy. LOR promotes desmoplasia (fibrosis and extracellular matrix protein deposition), inflammatory signaling, and ischemic necrosis. GPR68 is preferentially expressed on human PDAC CAFs, and n-unsubstituted BZDs, such as LOR, significantly increase IL6 expression and secretion in CAFs in a pH and GPR68-dependent manner. Conversely, ALP and other GPR68 n-substituted BZDs decrease IL6 in human CAFs in a pH and GPR68-independent manner. Across many cancer types, LOR is associated with worse survival outcomes relative to ALP and patients not receiving BZDs. We demonstrate that LOR stimulates fibrosis and inflammatory signaling, promotes desmoplasia and ischemic necrosis, and is associated with decreased pancreatic cancer patient survival.

Locoregional Therapies and Remodeling of Tumor Microenvironment in Pancreatic Cancer.

Despite the advances made in treatment, the prognosis of pancreatic ductal adenocarcinoma (PDAC) remains dismal, even in the locoregional and locally advanced stages, with high relapse rates after surgery. PDAC exhibits a chemoresistant and immunosuppressive phenotype, and the tumor microenvironment (TME) surrounding cancer cells actively participates in creating a stromal barrier to chemotherapy and an immunosuppressive environment. Recently, there has been an increasing use of interventional radiology techniques for the treatment of PDAC, although they do not represent a standard of care and are not included in clinical guidelines. Local approaches such as radiation therapy, hyperthermia, microwave or radiofrequency ablation, irreversible electroporation and high-intensity focused ultrasound exert their action on the tumor tissue, altering the composition and structure of TME and potentially enhancing the action of chemotherapy. Moreover, their action can increase antigen release and presentation with T-cell activation and reduction tumor-induced immune suppression. This review summarizes the current evidence on locoregional therapies in PDAC and their effect on remodeling TME to make it more susceptible to the action of antitumor agents.

Identifying a baicalein-related prognostic signature contributes to prognosis prediction and tumor microenvironment of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant and lethal human cancers in the world due to its high metastatic potential, and patients with PDAC have a poor prognosis, yet quite little is understood regarding the underlying biological mechanisms of its high metastatic capacity. Baicalein has a dramatic anti-tumor function in the treatment of different types of cancer. However, the therapeutic effects of baicalein on human PDAC and its mechanisms of action have not been extensively understood. In order to explore the biological characteristic, molecular mechanisms, and potential clinical value of baicalein in inhibiting the metastatic capacity of PDAC. We performed several in vitro, in vivo, and in silico studies. We first examined the potential regulation of baicalein in the metastatic capacity of PDAC cells. We showed that baicalein could dramatically suppress liver metastasis of PDAC cells with highly metastatic potential in mice model. The high-throughput sequencing analysis was employed to explore the biological roles of baicalein in PDAC cells. We found that baicalein might be involved in the infiltration of Cancer-Associated Fibroblasts (CAF) in PDAC. Moreover, a baicalein-related risk model and a lncRNA-related model were built by Cox analysis according to the data set of PDAC from TCGA database which suggested a clinical value of baicalein. Finally, we revealed a potential downstream target of baicalein in PDAC, we proposed that baicalein might contribute to the infiltration of CAF via FGFBP1. Thus, we uncovered a novel role for baicalein in regulation of PDAC liver metastasis that may contribute to its anti-cancer effect. We proposed that baicalein might suppress PDAC liver metastasis via regulation of FGFBP1-mediated CAF infiltration. Our results provide a new perspective on clinical utility of baicalein and open new avenues for the inhibition of liver-metastasis of PDAC.

A Tumor Microenvironment Model of Pancreatic Cancer to Elucidate Responses toward Immunotherapy (Adv. Healthcare Mater. 14/2023)

3D Cancer Models In article 2201907 by Daniela Loessner and co-workers, the tumor microenvironment of pancreatic cancer is engineered using star poly(ethylene glycol) (PEG)–heparin hydrogels, that are functionalized with integrin-binding and protease-responsive peptides to stimulate cell proliferation and migration. The coculture of cancer cells and patient-derived stromal cells mimics the multicellular composition of tumor tissues and cancer–immune interactions and allows the testing of immunomodulatory treatments in combination with chemotherapy.

Distribution characteristics and clinical significance of infiltrating Tcells in the tumor microenvironment of pancreatic cancer.

Tumor-infiltrating lymphocytes (TILs) are important components of the tumor microenvironment (TME). However, the distribution characteristics of TILs and their significance in pancreatic cancer (PC) remain largely unexplored. The levels of TILs, including the total number of T cells, cluster of differentiation (CD)4+ T cells, CD8+ cytotoxic T lymphocytes (CTLs), regulatory T-cells (Tregs), programmed cell death protein 1+ T cells and programmed cell death ligand 1 (PD-L1)+ T cells, in the TME of patients with PC were detected using multiple fluorescence immunohistochemistry. The associations between the number of TILs and the clinicopathological characteristics were investigated using χ2 tests. In addition, Kaplan-Meier survival and Cox regression analyses were used to assess the prognostic value of these TIL types. Compared with paracancerous tissues, in PC tissues, the proportions of total T cells, CD4+ T cells and CD8+ CTLs were markedly decreased, while those of Tregs and PD-L1+ T cells were significantly increased. The levels of CD4+ T cell and CD8+ CTL infiltrates were inversely associated with tumor differentiation. Higher infiltrates of Tregs and PD-L1+ T cells were closely associated with advanced N and TNM stages. It is important to note that the infiltrates of total T cells, CD4+ T cells, Tregs and PD-L1+ T cells in the TME were independent risk factors for the prognosis of PC. PC was characterized by an immunosuppressive TME with a decrease in the number of CD4+ T cells and CD8+ CTLs, and an increase in the number of Tregs and PD-L1+ T cells. Overall, the number of total T cells, CD4+ T cells, Tregs and PD-L1+ T cells in the TME was a potential predictive marker for the prognosis of PC.