TNF-α-producing macrophages determine subtype identity and prognosis via AP1 enhancer reprogramming in pancreatic cancer

Comprehensive multi-omics profiling identifies novel molecular subtypes of pancreatic ductal adenocarcinoma

Pancreatic cancer, a highly fatal malignancy, is predicted to rank as the second leading cause of cancer-related death in the next decade. This highlights the urgent need for new insights into personalized diagnosis and treatment. Although molecular subtypes of pancreatic cancer were well established in genomics and transcriptomics, few known molecular classifications are translated to guide clinical strategies and require a paradigm shift. Notably, chronically developing and continuously improving high-throughput technologies and systems serve as an important driving force to further portray the molecular landscape of pancreatic cancer in terms of epigenomics, proteomics, metabonomics, and metagenomics. Therefore, a more comprehensive understanding of molecular classifications at multiple levels using an integrated multi-omics approach holds great promise to exploit more potential therapeutic options. In this review, we recapitulated the molecular spectrum from different omics levels, discussed various subtypes on multi-omics means to move one step forward towards bench-to-beside translation of pancreatic cancer with clinical impact, and proposed some methodological and scientific challenges in store.

The Exon Junction Complex component EIF4A3 plays a splicing-linked oncogenic role in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, underscoring the urgent need for in-depth biological research. The phenomenon of alternative RNA splicing dysregulation is a common hallmark in cancer, including PDAC, presenting new avenues for understanding and developing diagnostic and therapeutic tools. Our research focuses on EIF4A3, a core component of the Exon Junction Complex intimately linked to RNA splicing, and its role in PDAC. EIF4A3 is overexpressed in PDAC tissue and associated to clinical parameters of malignancy and poorer patient survival. Mechanistically, exploration of PDAC RNA-seq data unveiled the link of EIF4A3 to diverse malignancy processes, consistent with its association to key molecular pathways. EIF4A3 targeting in vitro decreased essential functional tumor features such as proliferation, migration, colony formation and sphere formation, while its in vivo targeting reduced tumor growth. EIF4A3 silencing in PDAC cell lines severely altered its transcriptional and spliceosomic landscapes, as shown by RNA-seq analyses, suggesting a role for EIF4A3 in maintaining RNA homeostasis. Our results indicate that EIF4A3 dysregulation in PDAC has a pleiotropic regulatory role on RNA biology, influencing key cellular functions. This paves the way to explore its potential as novel biomarker and actionable target candidate for this lethal cancer.

Spatially resolved analysis of pancreatic cancer identifies therapy-associated remodeling of the tumor microenvironment

In combination with cell-intrinsic properties, interactions in the tumor microenvironment modulate therapeutic response. We leveraged single-cell spatial transcriptomics to dissect the remodeling of multicellular neighborhoods and cell-cell interactions in human pancreatic cancer associated with neoadjuvant chemotherapy and radiotherapy. We developed spatially constrained optimal transport interaction analysis (SCOTIA), an optimal transport model with a cost function that includes both spatial distance and ligand-receptor gene expression. Our results uncovered a marked change in ligand-receptor interactions between cancer-associated fibroblasts and malignant cells in response to treatment, which was supported by orthogonal datasets, including an ex vivo tumoroid coculture system. We identified enrichment in interleukin-6 family signaling that functionally confers resistance to chemotherapy. Overall, this study demonstrates that characterization of the tumor microenvironment using single-cell spatial transcriptomics allows for the identification of molecular interactions that may play a role in the emergence of therapeutic resistance and offers a spatially based analysis framework that can be broadly applied to other contexts.

The Peptidoglycan Recognition Protein 1 confers immune evasive properties on pancreatic cancer stem cells

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) has limited therapeutic options, particularly with immune checkpoint inhibitors. Highly chemoresistant 'stem-like' cells, known as cancer stem cells (CSCs), are implicated in PDAC aggressiveness. Thus, comprehending how this subset of cells evades the immune system is crucial for advancing novel therapies.

DESIGN

We used the KPC mouse model (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre) and primary tumour cell lines to investigate putative CSC populations. Transcriptomic analyses were conducted to pinpoint new genes involved in immune evasion. Overexpressing and knockout cell lines were established with lentiviral vectors. Subsequent in vitro coculture assays, in vivo mouse and zebrafish tumorigenesis studies, and in silico database approaches were performed.

RESULTS

Using the KPC mouse model, we functionally confirmed a population of cells marked by EpCAM, Sca-1 and CD133 as authentic CSCs and investigated their transcriptional profile. Immune evasion signatures/genes, notably the gene peptidoglycan recognition protein 1 (PGLYRP1), were significantly overexpressed in these CSCs. Modulating PGLYRP1 impacted CSC immune evasion, affecting their resistance to macrophage-mediated and T-cell-mediated killing and their tumourigenesis in immunocompetent mice. Mechanistically, tumour necrosis factor alpha (TNFα)-regulated PGLYRP1 expression interferes with the immune tumour microenvironment (TME) landscape, promoting myeloid cell-derived immunosuppression and activated T-cell death. Importantly, these findings were not only replicated in human models, but clinically, secreted PGLYRP1 levels were significantly elevated in patients with PDAC.

CONCLUSIONS

This study establishes PGLYRP1 as a novel CSC-associated marker crucial for immune evasion, particularly against macrophage phagocytosis and T-cell killing, presenting it as a promising target for PDAC immunotherapy.

Breaking Down Barriers in Drug Delivery by Stromal Remodeling Approaches in Pancreatic Cancer

Pancreatic cancer remains a formidable challenge in oncology due to its aggressive nature and limited treatment options. The dense stroma surrounding pancreatic tumors not only provides structural support but also presents a formidable barrier to effective therapy, hindering drug penetration and immune cell infiltration. This review delves into the intricate interplay between stromal components and cancer cells, highlighting their impact on treatment resistance and prognosis. Strategies for stromal remodeling, including modulation of cancer-associated fibroblasts (CAFs), pancreatic stellate cells (PSCs) activation states, and targeting extracellular matrix (ECM) components, are examined for their potential to enhance drug penetration and improve therapeutic efficacy. Integration of stromal remodeling with conventional therapies, such as chemotherapy and immunotherapy, is discussed along with the emerging field of intelligent nanosystems for targeted drug delivery. This comprehensive overview underscores the importance of stromal remodeling in pancreatic cancer treatment and offers insights into promising avenues for future research and clinical translation.

Pan-Cancer Single-Cell and Spatial-Resolved Profiling Reveals the Immunosuppressive Role of APOE+ Macrophages in Immune Checkpoint Inhibitor Therapy

The heterogeneity of macrophages influences the response to immune checkpoint inhibitor (ICI) therapy. However, few studies explore the impact of APOE+ macrophages on ICI therapy using single-cell RNA sequencing (scRNA-seq) and machine learning methods. The scRNA-seq and bulk RNA-seq data are Integrated to construct an M.Sig model for predicting ICI response based on the distinct molecular signatures of macrophage and machine learning algorithms. Comprehensive single-cell analysis as well as in vivo and in vitro experiments are applied to explore the potential mechanisms of the APOE+ macrophage in affecting ICI response. The M.Sig model shows clear advantages in predicting the efficacy and prognosis of ICI therapy in pan-cancer patients. The proportion of APOE+ macrophages is higher in ICI non-responders of triple-negative breast cancer compared with responders, and the interaction and longer distance between APOE+ macrophages and CD8+ exhausted T (Tex) cells affecting ICI response is confirmed by multiplex immunohistochemistry. In a 4T1 tumor-bearing mice model, the APOE inhibitor combined with ICI treatment shows the best efficacy. The M.Sig model using real-world immunotherapy data accurately predicts the ICI response of pan-cancer, which may be associated with the interaction between APOE+ macrophages and CD8+ Tex cells.

Role of pyroptosis-related cytokines in the prediction of lung cancer

Objectives

Lung cancer is the leading cause to induce cancer-related mortality. Effective biomarkers for prediction the occurrence of lung cancer is urgently needed. Our previous studies indicated that pyroptosis-related cytokines TNF-α, IFN-γ, MIP-1α, MIP-1β, MIP-2 and IP-10 is important to influence the efficacy of chemotherapy drug in lung cancer tissues. But the role of pyroptosis-related cytokines in prediction the occurrence of lung cancer is still unknown.

Methods

Blood samples were collected from 258 lung cancer patients at different stage and 80 healthy volunteers. Serum levels of pyroptosis-related cytokines including TNF-α, IFN-γ, MIP-1α, MIP-1β, MIP-2 and IP-10 were measured by Cytometric Bead Array (CBA). ROC curve was performed to evaluate the cut-off value and diagnosis value for prediction and diagnosis of lung cancer.

Results

Compared with control group, the levels of IP-10, MIP-1α, MIP-1β, MIP-2 and TNF-α were significantly higher in lung cancer patients (45.5 (37.1-56.7): 57.2 (43.0-76.5), 34.4 (21.8-75.2): 115.4 (96.6-191.2), 49.3 (25.6-78.7): 160.5 (124.9-218.6), 22.6 (17.8-31.2): 77.9 (50.1-186.5), 3.80 (2.3-6.2): 10.3 (5.7-16.6)), but the level of IFN-γ was decreased in the patients (12.38 (9.1-27.8): 5.9 (3.5-9.7)). All the above cytokines were significantly associated with the diagnosis of lung cancer, and the AUC values of IFN-γ, IP-10, MIP-1α, MIP-1β, MIP-2, and TNF-α were 0.800, 0.656, 0.905, 0.921, 0.914, and 0.824. And the AUC can rise to 0.986 after combining the above factors, and the sensitivity and specificity also up to 96.7 % and 93.7 %, respectively. Additionally, TNF-α (r = 0.400, P < 0.01), MIP-2 (r = 0.343, P < 0.01), MIP-1α (r = 0.551, P < 0.01) and MIP-1β (r = 0.403, p < 0.01) were positively associated with occurrence of lung cancer, but IFN-γ (r = -0.483, p < 0.01) was negatively associated with occurrence of lung cancer. As far as the potential of early diagnosis of lung cancer, TNF-α (AUC = 0.577), MIP-1α (AUC = 0.804) and MIP-1β (AUC = 0.791) can predict the early stage of lung cancer, and combination of the above three cytokines has a better predictive efficiency (AUC = 0.854).

Conclusion

Our study establishes a link between the levels of IP-10, MIP-1α, MIP-1β, MIP-2, TNF-α and IFN-γ and diagnosis of lung cancer. Besides, we observed a synergistic effect of these five pyroptosis-related cytokines in diagnosing lung cancer patient, suggesting their potential as biomarkers for lung cancer diagnosis. Moreover, the combination of TNF-α, MIP-1α and MIP-1β are also potential predictors for the early diagnosis of lung cancer.

GATA6 identifies an immune-enriched phenotype linked to favorable outcomes in patients with pancreatic cancer undergoing upfront surgery

This study underscores GATA6's role in distinguishing classical and basal-like pancreatic ductal adenocarcinoma (PDAC) phenotypes. Retrospective studies associate GATA6 immunohistochemistry (IHC) expression with survival outcomes, warranting prospective validation. In a prospective treatment-naive cohort of patients with resected PDAC, GATA6 IHC proves a prognostic discriminator, associating high GATA6 expression with extended survival and the classical PDAC phenotype. However, GATA6's prognostic significance is numerically lower after gemcitabine-based neoadjuvant chemoradiotherapy compared to its significance in patients treated with upfront surgery. Furthermore, GATA6 is implicated in immunomodulation, although a comprehensive investigation of its immunological role is lacking. Treatment-naive PDAC tumors with varying GATA6 expression yield distinct immunological landscapes. Tumors highly expressing GATA6 show reduced infiltration of immunosuppressive regulatory T cells and M2 macrophages but increased infiltration of immune-stimulating, antigen-presenting, and activated T cells. Our findings caution against solely relying on GATA6 for molecular subtyping in clinical trials and open avenues for exploring immune-based combination therapies.

Fundamental insights and molecular interactions in pancreatic cancer: Pathways to therapeutic approaches

The gastrointestinal tract can be affected by a number of diseases that pancreatic cancer (PC) is a malignant manifestation of them. The prognosis of PC patients is unfavorable and because of their diagnosis at advanced stage, the treatment of this tumor is problematic. Owing to low survival rate, there is much interest towards understanding the molecular profile of PC in an attempt in developing more effective therapeutics. The conventional therapeutics for PC include surgery, chemotherapy and radiotherapy as well as emerging immunotherapy. However, PC is still incurable and more effort should be performed. The molecular landscape of PC is an underlying factor involved in increase in progression of tumor cells. In the presence review, the newest advances in understanding the molecular and biological events in PC are discussed. The dysregulation of molecular pathways including AMPK, MAPK, STAT3, Wnt/β-catenin and non-coding RNA transcripts has been suggested as a factor in development of tumorigenesis in PC. Moreover, cell death mechanisms such as apoptosis, autophagy, ferroptosis and necroptosis demonstrate abnormal levels. The EMT and glycolysis in PC cells enhance to ensure their metastasis and proliferation. Furthermore, such abnormal changes have been used to develop corresponding pharmacological and nanotechnological therapeutics for PC.

FAM53B promotes pancreatic ductal adenocarcinoma metastasis by regulating macrophage M2 polarization

BACKGROUND

Our study investigated the role of FAM53B in regulating macrophage M2 polarization and its potential mechanisms in promoting pancreatic ductal adenocarcinoma (PDAC) metastasis.

AIM

To further investigate the role of FAM53B in regulating macrophage M2 polarization and its potential mechanism in promoting PDAC metastasis. Our goal is to determine how FAM53B affects macrophage M2 polarization and to define its underlying mechanism in PDAC metastasis.

METHODS

Cell culture and various experiments, including protein analysis, immunohistochemistry, and animal model experiments, were conducted. We compared FAM53B expression between PDAC tissues and healthy tissues and assessed the correlation of FAM53B expression with clinical features. Our study analyzed the role of FAM53B in macrophage M2 polarization in vitro by examining the expression of relevant markers. Finally, we used a murine model to study the role of FAM53B in PDAC metastasis and analyzed the potential underlying mechanisms.

RESULTS

Our research showed that there was a significant increase in FAM53B levels in PDAC tissues, which was linked to adverse tumor features. Experimental findings indicated that FAM53B can enhance macrophage M2 polarization, leading to increased anti-inflammatory factor release. The results from the mouse model further supported the role of FAM53B in PDAC metastasis, as blocking FAM53B prevented tumor cell invasion and metastasis.

CONCLUSION

FAM53B promotes PDAC metastasis by regulating macrophage M2 polarization. This discovery could lead to the development of new strategies for treating PDAC. For example, interfering with the FAM53B signaling pathway may prevent cancer spread. Our research findings also provide important information for expanding our understanding of PDAC pathogenesis.

Mapping functional to morphological variation reveals the basis of regional extracellular matrix subversion and nerve invasion in pancreatic cancer

Intratumor morphological heterogeneity of pancreatic ductal adenocarcinoma (PDAC) predicts clinical outcomes but is only partially understood at the molecular level. To elucidate the gene expression programs underpinning intratumor morphological variation in PDAC, we investigated and deconvoluted at single cell level the molecular profiles of histologically distinct clusters of PDAC cells. We identified three major morphological and functional variants that co-exist in varying proportions in all PDACs, display limited genetic diversity, and are associated with a distinct organization of the extracellular matrix: a glandular variant with classical ductal features; a transitional variant displaying abortive ductal structures and mixed endodermal and myofibroblast-like gene expression; and a poorly differentiated variant lacking ductal features and basement membrane, and showing neuronal lineage priming. Ex vivo and in vitro evidence supports the occurrence of dynamic transitions among these variants in part influenced by extracellular matrix composition and stiffness and associated with local, specifically neural, invasion.

Alteration of chromosome structure impacts gene expressions implicated in pancreatic ductal adenocarcinoma cells

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a five-year survival rate of approximately 10%. Genetic mutations are pivotal drivers in PDAC pathogenesis, but recent investigations also revealed the involvement of non-genetic alterations in the disease development. In this study, we undertook a multi-omics approach, encompassing ATAC-seq, RNA-seq, ChIP-seq, and Hi-C methodologies, to dissect gene expression alterations arising from changes in chromosome accessibility and chromatin three-dimensional interactions in PDAC.

RESULTS

Our findings indicate that chromosomal structural alterations can lead to abnormal expressions on key genes during PDAC development. Notably, overexpression of oncogenes FGFR2, FOXA2, CYP2R1, and CPOX can be attributed to the augmentation of promoter accessibility, coupled with long-range interactions with distal elements. Additionally, our findings indicate that chromosomal structural alterations caused by genomic instability can lead to abnormal expressions in PDACs. As an example, by analyzing chromosomal changes, we identified a putative oncogenic gene, LPAR1, which shows upregulated expression in both PDAC cell lines and clinical samples. The overexpression is correlated with alterations in LPAR1-associated 3D genome structure and chromatin state. We further demonstrated that high LPAR1 activity is required for enhanced PDAC cell migration in vitro.

CONCLUSIONS

Collectively, our findings reveal that the chromosomal conformational alterations, in addition to the well-known genetic mutations, are critical for PDAC tumorigenesis.

Innate and adaptive immune-directed tumour microenvironment in pancreatic ductal adenocarcinoma

One of the most deadly and aggressive cancers in the world, pancreatic ductal adenocarcinoma (PDAC), typically manifests at an advanced stage. PDAC is becoming more common, and by the year 2030, it is expected to overtake lung cancer as the second greatest cause of cancer-related death. The poor prognosis can be attributed to a number of factors, including difficulties in early identification, a poor probability of curative radical resection, limited response to chemotherapy and radiotherapy, and its immunotherapy resistance. Furthermore, an extensive desmoplastic stroma that surrounds PDAC forms a mechanical barrier that prevents vascularization and promotes poor immune cell penetration. Phenotypic heterogeneity, drug resistance, and immunosuppressive tumor microenvironment are the main causes of PDAC aggressiveness. There is a complex and dynamic interaction between tumor cells in PDAC with stromal cells within the tumour immune microenvironment. The immune suppressive microenvironment that promotes PDAC aggressiveness is contributed by a range of cellular and humoral factors, which itself are modulated by the cancer. In this review, we describe the role of innate and adaptive immune cells, complex tumor microenvironment in PDAC, humoral factors, innate immune-mediated therapeutic advances, and recent clinical trials in PDAC.

Molecular mechanisms of tumour necrosis factor signalling via TNF receptor 1 and TNF receptor 2 in the tumour microenvironment

Tumour necrosis factor (TNF) is a primary mediator of inflammatory processes by facilitating cell death, immune cell activation and triggering of inflammation. In the cancer context, research has revealed TNF as a multifaceted cytokine that can be both pro- or anti-tumorigenic depending on what context is observed. We explore the plethora of ways that TNF and its receptors manipulate the functional and phenotypic characteristics in the tumour microenvironment (TME) on both tumour cells and immune cells, promoting either tumour elimination or progression. Here, we discuss the latest cutting-edge TNF-focused biologics currently in clinical translation that modifies the TME to derive greater immune responses and therapeutic outcomes, and further give perspectives on the future of targeting TNF in the context of cancer by emerging technological approaches.

Targeting the macrophage immunocheckpoint: a novel insight into solid tumor immunotherapy

Tumor immunotherapy, which targets immune checkpoints, presents a promising strategy for the treatment of various cancer types. However, current clinical data indicate challenges in its application to solid tumors. Recent studies have revealed a significant correlation between the degree of immune response in immunotherapy and the tumor microenvironment, particularly with regard to tumor-infiltrating immune cells. Among these immune cells, macrophages, a critical component, are playing an increasingly vital role in tumor immunotherapy. This review focuses on elucidating the role of macrophages within solid tumors and provides an overview of the progress in immunotherapy approaches centered around modulating macrophage responses through various immune factors. Video Abstract.

ROR2 regulates cellular plasticity in pancreatic neoplasia and adenocarcinoma

Cellular plasticity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) starting from the conversion of normal cells into precancerous lesions to the progression of carcinoma subtypes associated with aggressiveness and therapeutic response. We discovered that normal acinar cell differentiation, maintained by the transcription factor Pdx1, suppresses a broad gastric cell identity that is maintained in metaplasia, neoplasia, and the classical subtype of PDAC in mouse and human. We have identified the receptor tyrosine kinase Ror2 as marker of a gastric metaplasia (SPEM)-like identity in the pancreas. Ablation of Ror2 in a mouse model of pancreatic tumorigenesis promoted a switch to a gastric pit cell identity that largely persisted through progression to the classical subtype of PDAC. In both human and mouse pancreatic cancer, ROR2 activity continued to antagonize the gastric pit cell identity, strongly promoting an epithelial to mesenchymal transition, conferring resistance to KRAS inhibition, and vulnerability to AKT inhibition.

Tumor immune microenvironment-based therapies in pancreatic ductal adenocarcinoma: time to update the concept

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. The tumor immune microenvironment (TIME) formed by interactions among cancer cells, immune cells, cancer-associated fibroblasts (CAF), and extracellular matrix (ECM) components drives PDAC in a more immunosuppressive direction: this is a major cause of therapy resistance and poor prognosis. In recent years, research has advanced our understanding of the signaling mechanism by which TIME components interact with the tumor and the evolution of immunophenotyping. Through revolutionary technologies such as single-cell sequencing, we have gone from simply classifying PDACs as "cold" and "hot" to a more comprehensive approach of immunophenotyping that considers all the cells and matrix components. This is key to improving the clinical efficacy of PDAC treatments. In this review, we elaborate on various TIME components in PDAC, the signaling mechanisms underlying their interactions, and the latest research into PDAC immunophenotyping. A deep understanding of these network interactions will contribute to the effective combination of TIME-based therapeutic approaches, such as immune checkpoint inhibitors (ICI), adoptive cell therapy, therapies targeting myeloid cells, CAF reprogramming, and stromal normalization. By selecting the appropriate integrated therapies based on precise immunophenotyping, significant advances in the future treatment of PDAC are possible.

Multicenter randomized controlled trial of neoadjuvant chemoradiotherapy alone or in combination with pembrolizumab in patients with resectable or borderline resectable pancreatic adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a challenging target for immunotherapy because it has an immunosuppressive tumor microenvironment. Neoadjuvant chemoradiotherapy can increase tumor-infiltrating lymphocyte (TIL) density, which may predict overall survival (OS). We hypothesized that adding programmed cell death protein 1 (PD-1) blockade to chemoradiotherapy would be well tolerated and increase TILs among patients with localized PDAC.

METHODS

Patients were randomized 2:1 to Arm A (receiving pembrolizumab plus chemoradiotherapy (capecitabine and external beam radiation)) or Arm B (receiving chemoradiotherapy alone) before anticipated pancreatectomy. Primary endpoints were (1) incidence and severity of adverse events during neoadjuvant therapy and (2) density of TILs in resected tumor specimens. TIL density was assessed using multiplexed immunofluorescence histologic examination.

RESULTS

Thirty-seven patients were randomized to Arms A (n=24) and B (n=13). Grade ≥3 adverse events related to neoadjuvant treatment were experienced by 9 (38%) and 4 (31%) patients in Arms A and B, respectively, with one patient experiencing dose-limiting toxicity in Arm A. Seventeen (71%) and 7 (54%) patients in Arms A and B, respectively, underwent pancreatectomy. Median CD8+ T-cell densities in Arms A and B were 67.4 (IQR: 39.2-141.8) and 37.9 (IQR: 22.9-173.4) cells/mm2, respectively. Arms showed no noticeable differences in density of CD8+Ki67+, CD4+, or CD4+FOXP3+ regulatory T cells; M1-like and M2-like macrophages; or granulocytes. Median OS durations were 27.8 (95% CI: 17.1 to NR) and 24.3 (95% CI: 12.6 to NR) months for Arms A and B, respectively.

CONCLUSIONS

Adding pembrolizumab to neoadjuvant chemoradiotherapy was safe. However, no convincing effect on CD8+ TILs was observed.

Epigenetic control of pancreatic cancer metastasis

Surgical resection, when combined with chemotherapy, has been shown to significantly improve the survival rate of patients with pancreatic ductal adenocarcinoma (PDAC). However, this treatment option is only feasible for a fraction of patients, as more than 50% of cases are diagnosed with metastasis. The multifaceted process of metastasis is still not fully understood, but recent data suggest that transcriptional and epigenetic plasticity play significant roles. Interfering with epigenetic reprogramming can potentially control the adaptive processes responsible for metastatic progression and therapy resistance, thereby enhancing treatment responses and preventing recurrence. This review will focus on the relevance of histone-modifying enzymes in pancreatic cancer, specifically on their impact on the metastatic cascade. Additionally, it will also provide a brief update on the current clinical developments in epigenetic therapies.

Good CARMA: Turning bad tumor-resident myeloid cells good with chimeric antigen receptor macrophages

In religious philosophy, the concept of karma represents the effect of one's past and present actions on one's future. Macrophages are highly plastic cells with myriad roles in health and disease. In the setting of cancer, macrophages are among the most plentiful members of the immune microenvironment where they generally support tumor growth and restrain antitumor immunity. However, macrophages are not necessarily born bad. Macrophages or their immediate progenitors, monocytes, are induced to traffic to the tumor microenvironment (TME) and during this process they are polarized toward a tumor-promoting phenotype. Efforts to deplete or repolarize tumor-associated macrophages (TAM) for therapeutic benefit in cancer have to date disappointed. By contrast, genetic engineering of macrophages followed by their transit into the TME may allow these impressionable cells to mend their ways. In this review, we summarize and discuss recent advances in the genetic engineering of macrophages for the treatment of cancer.

Tumour-associated macrophages: versatile players in the tumour microenvironment

Tumour-Associated Macrophages (TAMs) are one of the pivotal components of the tumour microenvironment. Their roles in the cancer immunity are complicated, both pro-tumour and anti-cancer activities are reported, including not only angiogenesis, extracellular matrix remodeling, immunosuppression, drug resistance but also phagocytosis and tumour regression. Interestingly, TAMs are highly dynamic and versatile in solid tumours. They show anti-cancer or pro-tumour activities, and interplay between the tumour microenvironment and cancer stem cells and under specific conditions. In addition to the classic M1/M2 phenotypes, a number of novel dedifferentiation phenomena of TAMs are discovered due to the advanced single-cell technology, e.g., macrophage-myofibroblast transition (MMT) and macrophage-neuron transition (MNT). More importantly, emerging information demonstrated the potential of TAMs on cancer immunotherapy, suggesting by the therapeutic efficiency of the checkpoint inhibitors and chimeric antigen receptor engineered cells based on macrophages. Here, we summarized the latest discoveries of TAMs from basic and translational research and discussed their clinical relevance and therapeutic potential for solid cancers.

Methylation of BRD4 by PRMT1 regulates BRD4 phosphorylation and promotes ovarian cancer invasion

Bromodomain-containing protein 4 (BRD4), the major component of bromodomain and extra-terminal domain (BET) protein family, has important functions in early embryonic development and cancer development. However, the posttranslational modification of BRD4 is not well understood. Multiple approaches were used to explore the mechanism of PRMT1-mediated BRD4 methylation and to determine the biological functions of BRD4 and PRMT1 in ovarian cancer. Here we report that BRD4 is asymmetrically methylated at R179/181/183 by PRMT1, which is antagonized by the Jumonji-family demethylase, JMJD6. PRMT1 is overexpressed in ovarian cancer tissue and is a potential marker for poor prognosis in ovarian cancer patients. Silencing of PRMT1 inhibited ovarian cancer proliferation, migration, and invasion in vivo and in vitro. PRMT1-mediated BRD4 methylation was found to promote BRD4 phosphorylation. Compared to BRD4 wild-type (WT) cells, BRD4 R179/181/183K mutant-expressing cells showed reduced ovarian cancer metastasis. BRD4 arginine methylation is also associated with TGF-β signaling. Our results indicate that arginine methylation of BRD4 by PRMT1 is involved in ovarian cancer tumorigenesis. Targeting PRMT1-mediated arginine methylation may provide a novel diagnostic target and an effective therapeutic strategy for ovarian cancer treatment.

Roles of differently polarized macrophages in the initiation and progressionof pancreatic cancer

During development of pancreatic cancer macrophage-mediated inflammatory processes and the formation of cancerous lesions are tightly connected. Based on insight from mouse models we provide an overview on the functions of classically-activated pro-inflammatory and alternatively-activated anti-inflammatory macrophages in the initiation and progression of pancreatic cancer. We highlight their roles in earliest events of tumor initiation such as acinar-to-ductal metaplasia (ADM), organization of the fibrotic lesion microenvironment, and growth of low-grade (LG) lesions. We then discuss their roles as tumor-associated macrophages (TAM) in progression to high-grade (HG) lesions with a cancerous invasive phenotype and an immunosuppressive microenvironment. Another focus is on how targeting these macrophage populations can affect immunosuppression, fibrosis and responses to chemotherapy, and eventually how this knowledge could be used for novel therapy approaches for patients with pancreatic ductal adenocarcinoma (PDA).

IL-17A-producing CD8+ T cells promote PDAC via induction of inflammatory cancer-associated fibroblasts

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant desmoplastic stroma composed of cancer-associated fibroblasts (CAF) and interspersed immune cells. A non-canonical CD8+ T-cell subpopulation producing IL-17A (Tc17) promotes autoimmunity and has been identified in tumours. Here, we evaluated the Tc17 role in PDAC.

DESIGN

Infiltration of Tc17 cells in PDAC tissue was correlated with patient overall survival and tumour stage. Wild-type (WT) or Il17ra-/- quiescent pancreatic stellate cells (qPSC) were exposed to conditional media obtained from Tc17 cells (Tc17-CM); moreover, co-culture of Tc17-CM-induced inflammatory (i)CAF (Tc17-iCAF) with tumour cells was performed. IL-17A/F-, IL-17RA-, RAG1-deficient and Foxn1nu/nu mice were used to study the Tc17 role in subcutaneous and orthotopic PDAC mouse models.

RESULTS

Increased abundance of Tc17 cells highly correlated with reduced survival and advanced tumour stage in PDAC. Tc17-CM induced iCAF differentiation as assessed by the expression of iCAF-associated genes via synergism of IL-17A and TNF. Accordingly, IL-17RA controlled the responsiveness of qPSC to Tc17-CM. Pancreatic tumour cells co-cultured with Tc17-iCAF displayed enhanced proliferation and increased expression of genes implicated in proliferation, metabolism and protection from apoptosis. Tc17-iCAF accelerated growth of mouse and human tumours in Rag1-/- and Foxn1nu/nu mice, respectively. Finally, Il17ra-expressed by fibroblasts was required for Tc17-driven tumour growth in vivo.

CONCLUSIONS

We identified Tc17 as a novel protumourigenic CD8+ T-cell subtype in PDAC, which accelerated tumour growth via IL-17RA-dependent stroma modification. We described a crosstalk between three cell types, Tc17, fibroblasts and tumour cells, promoting PDAC progression, which resulted in poor prognosis for patients.

Chromatin accessibility uncovers KRAS-driven FOSL2 promoting pancreatic ductal adenocarcinoma progression through up-regulation of CCL28

BACKGROUND

The epigenetic mechanisms involved in the progression of pancreatic ductal adenocarcinoma (PDAC) remain largely unexplored. This study aimed to identify key transcription factors (TFs) through multiomics sequencing to investigate the molecular mechanisms of TFs that play critical roles in PDAC.

METHODS

To characterise the epigenetic landscape of genetically engineered mouse models (GEMMs) of PDAC with or without KRAS and/or TP53 mutations, we employed ATAC-seq, H3K27ac ChIP-seq, and RNA-seq. The effect of Fos-like antigen 2 (FOSL2) on survival was assessed using the Kaplan-Meier method and multivariate Cox regression analysis for PDAC patients. To study the potential targets of FOSL2, we performed Cleavage Under Targets and Tagmentation (CUT&Tag). To explore the functions and underlying mechanisms of FOSL2 in PDAC progression, we employed several assays, including CCK8, transwell migration and invasion, RT-qPCR, Western blotting analysis, IHC, ChIP-qPCR, dual-luciferase reporter, and xenograft models.

RESULTS

Our findings indicated that epigenetic changes played a role in immunosuppressed signalling during PDAC progression. Moreover, we identified FOSL2 as a critical regulator that was up-regulated in PDAC and associated with poor prognosis in patients. FOSL2 promoted cell proliferation, migration, and invasion. Importantly, our research revealed that FOSL2 acted as a downstream target of the KRAS/MAPK pathway and recruited regulatory T (Treg) cells by transcriptionally activating C-C motif chemokine ligand 28 (CCL28). This discovery highlighted the role of an immunosuppressed regulatory axis involving KRAS/MAPK-FOSL2-CCL28-Treg cells in the development of PDAC.

CONCLUSION

Our study uncovered that KRAS-driven FOSL2 promoted PDAC progression by transcriptionally activating CCL28, revealing an immunosuppressive role for FOSL2 in PDAC.

Therapy-associated remodeling of pancreatic cancer revealed by single-cell spatial transcriptomics and optimal transport analysis

In combination with cell intrinsic properties, interactions in the tumor microenvironment modulate therapeutic response. We leveraged high-plex single-cell spatial transcriptomics to dissect the remodeling of multicellular neighborhoods and cell-cell interactions in human pancreatic cancer associated with specific malignant subtypes and neoadjuvant chemotherapy/radiotherapy. We developed Spatially Constrained Optimal Transport Interaction Analysis (SCOTIA), an optimal transport model with a cost function that includes both spatial distance and ligand-receptor gene expression. Our results uncovered a marked change in ligand-receptor interactions between cancer-associated fibroblasts and malignant cells in response to treatment, which was supported by orthogonal datasets, including an ex vivo tumoroid co-culture system. Overall, this study demonstrates that characterization of the tumor microenvironment using high-plex single-cell spatial transcriptomics allows for identification of molecular interactions that may play a role in the emergence of chemoresistance and establishes a translational spatial biology paradigm that can be broadly applied to other malignancies, diseases, and treatments.

Terpinen-4-ol Induces Ferroptosis of Glioma Cells via Downregulating JUN Proto-Oncogene

According to previous research, turmeric seeds exhibit anti-inflammatory, anti-malignancy, and anti-aging properties due to an abundance of terpinen-4-ol (T4O). Although it is still unclear how T4O works on glioma cells, limited data exist regarding its specific effects. In order to determine whether or not glioma cell lines U251, U87, and LN229 are viable, CCK8 was used as an assay and a colony formation assay was performed using different concentrations of T4O (0, 1, 2, and 4 μM). The effect of T4O on the proliferation of glioma cell line U251 was detected through the subcutaneous implantation of the tumor model. Through high-throughput sequencing, a bioinformatic analysis, and real-time quantitative polymerase chain reactions, we identified the key signaling pathways and targets of T4O. Finally, for the measurement of the cellular ferroptosis levels, we examined the relationship between T4O, ferroptosis, and JUN and the malignant biological properties of glioma cells. T4O significantly inhibited glioma cell growth and colony formation and induced ferroptosis in the glioma cells. T4O inhibited the subcutaneous tumor proliferation of the glioma cells in vivo. T4O suppressed JUN transcription and significantly reduced its expression in the glioma cells. The T4O treatment inhibited GPX4 transcription through JUN. The overexpression of JUN suppressed ferroptosis in the cells rescued through T4O treatment. Taken together, our data suggest that the natural product T4O exerts its anti-cancer effects by inducing JUN/GPX4-dependent ferroptosis and inhibiting cell proliferation, and T4O will hope-fully serve as a prospective compound for glioma treatment.

Pancreatic cancer epigenetics: adaptive metabolism reprograms starving primary tumors for widespread metastatic outgrowth

Pancreatic cancer is a paradigm for adaptation to extreme stress. That is because genetic drivers are selected during tissue injury with epigenetic imprints encoding wound healing responses. Ironically, epigenetic memories of trauma that facilitate neoplasia can also recreate past stresses to restrain malignant progression through symbiotic tumor:stroma crosstalk. This is best exemplified by positive feedback between neoplastic chromatin outputs and fibroinflammatory stromal cues that encase malignant glands within a nutrient-deprived desmoplastic stroma. Because epigenetic imprints are chemically encoded by nutrient-derived metabolites bonded to chromatin, primary tumor metabolism adapts to preserve malignant epigenetic fidelity during starvation. Despite these adaptations, stromal stresses inevitably awaken primordial drives to seek more hospitable climates. The invasive migrations that ensue facilitate entry into the metastatic cascade. Metastatic routes present nutrient-replete reservoirs that accelerate malignant progression through adaptive metaboloepigenetics. This is best exemplified by positive feedback between biosynthetic enzymes and nutrient transporters that saturate malignant chromatin with pro-metastatic metabolite byproducts. Here we present a contemporary view of pancreatic cancer epigenetics: selection of neoplastic chromatin under fibroinflammatory pressures, preservation of malignant chromatin during starvation stresses, and saturation of metastatic chromatin by nutritional excesses that fuel lethal metastasis.

Irbesartan overcomes gemcitabine resistance in pancreatic cancer by suppressing stemness and iron metabolism via inhibition of the Hippo/YAP1/c-Jun axis

BACKGROUND

Chemoresistance is the main reason for the poor prognosis of pancreatic ductal adenocarcinoma (PDAC). Thus, there is an urgent need to screen out new targets and compounds to reverse chemotherapeutic resistance.

METHODS

We established a bio-bank of human PDAC organoid models, covering a representative range of PDAC tumor subtypes. We screened a library of 1304 FDA-approved compounds to identify candidates efficiently overcoming chemotherapy resistance. The effects of the compounds were evaluated with a CellTiter-Glo-3D assay, organoid apoptosis assay and in vivo patient-derived xenograft (PDX), patient-derived organoid (PDO) and LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) genetically engineered mouse models. RNA-sequencing, genome editing, sphere formation assays, iron assays and luciferase assays were conducted to elucidate the mechanism.

RESULTS

High-throughput drug screening of chemotherapy-resistant PDOs identified irbesartan, an angiotensin ‖ type 1 (AT1) receptor antagonist, which could synergistically enhance the ability of chemotherapy to kill PDAC cells. In vitro and in vivo validation using PDO, PDX and KPC mouse models showed that irbesartan efficiently sensitized PDAC tumors to chemotherapy. Mechanistically, we found that irbesartan decreased c-Jun expression by inhibiting the Hippo/YAP1 pathway and further overcame chemotherapy resistance in PDAC. We also explored c-Jun, a potential target of irbesartan, which can transcriptionally upregulate the expression of key genes involved in stemness maintenance (SOX9/SOX2/OCT4) and iron metabolism (FTH1/FTL/TFRC). More importantly, we observed that PDAC patients with high levels of c-Jun expression demonstrated poor responses to the current standard chemotherapy regimen (gemcitabine plus nab-paclitaxel). Moreover, patients with PDAC had significant survival benefits from treatment with irbesartan plus a standard chemotherapy regimen in two-center retrospective clinical cohorts and patients with high c-Jun expression exhibited a better response to combination chemotherapy.

CONCLUSIONS

Irbesartan could be used in combination with chemotherapy to improve the therapeutic efficacy in PDAC patients with high levels of c-Jun expression. Irbesartan effectively inhibited chemotherapy resistance by suppressing the Hippo/YAP1/c-Jun/stemness/iron metabolism axis. Based on our findings, we are designing an investigator-initiated phase II clinical trial on the efficacy and safety of irbesartan plus a standard gemcitabine/nab-paclitaxel regimen in the treatment of patients with advanced III/IV staged PDAC and are hopeful that we will observe patient benefits.

Single-cell profiling to explore pancreatic cancer heterogeneity, plasticity and response to therapy

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer entity characterized by a heterogeneous genetic landscape and an immunosuppressive tumor microenvironment. Recent advances in high-resolution single-cell sequencing and spatial transcriptomics technologies have enabled an in-depth characterization of both malignant and host cell types and increased our understanding of the heterogeneity and plasticity of PDAC in the steady state and under therapeutic perturbation. In this Review we outline single-cell analyses in PDAC, discuss their implications on our understanding of the disease and present future perspectives of multimodal approaches to elucidate its biology and response to therapy at the single-cell level.

Macrophages at the interface of the co-evolving cancer ecosystem

Macrophages are versatile and heterogeneous innate immune cells undertaking central functions in balancing immune responses and tissue repair to maintain homeostasis. This plasticity, once co-opted by malignant outgrowth, orchestrates manifold reciprocal interactions within the tumor microenvironment, fueling the evolution of the cancer ecosystem. Here, we review the multilayered sources of influence that jointly underpin and longitudinally shape tumor-associated macrophage (TAM) phenotypic states in solid neoplasms. We discuss how, in response to these signals, TAMs steer tumor evolution in the context of natural selection, biological dispersion, and treatment resistance. A number of research frontiers to be tackled are laid down in this review to therapeutically exploit the complex roles of TAMs in cancer. Building upon knowledge obtained from currently applied TAM-targeting strategies and using next generation technologies, we propose conceptual advances and novel therapeutic avenues to rewire TAM multifaceted regulation of the co-evolving cancer ecosystem.

Context-Specific Determinants of the Immunosuppressive Tumor Microenvironment in Pancreatic Cancer

Immunotherapies have shown benefits across a range of human cancers, but not pancreatic ductal adenocarcinoma (PDAC). Recent evidence suggests that the immunosuppressive tumor microenvironment (TME) constitutes an important roadblock to their efficacy. The landscape of the TME differs substantially across PDAC subtypes, indicating context-specific principles of immunosuppression. In this review, we discuss how PDAC cells, the local TME, and systemic host and environmental factors drive immunosuppression in context. We argue that unraveling the mechanistic drivers of the context-specific modes of immunosuppression will open new possibilities to target PDAC more efficiently by using multimodal (immuno)therapeutic interventions.

SIGNIFICANCE

Immunosuppression is an almost universal hallmark of pancreatic cancer, although this tumor entity is highly heterogeneous across its different subtypes and phenotypes. Here, we provide evidence that the diverse TME of pancreatic cancer is a central executor of various different context-dependent modes of immunosuppression, and discuss key challenges and novel opportunities to uncover, functionalize, and target the central drivers and functional nodes of immunosuppression for therapeutic exploitation.

Compressed phenotypic screens for complex multicellular models and high-content assays

High-throughput phenotypic screens leveraging biochemical perturbations, high-content readouts, and complex multicellular models could advance therapeutic discovery yet remain constrained by limitations of scale. To address this, we establish a method for compressing screens by pooling perturbations followed by computational deconvolution. Conducting controlled benchmarks with a highly bioactive small molecule library and a high-content imaging readout, we demonstrate increased efficiency for compressed experimental designs compared to conventional approaches. To prove generalizability, we apply compressed screening to examine transcriptional responses of patient-derived pancreatic cancer organoids to a library of tumor-microenvironment (TME)-nominated recombinant protein ligands. Using single-cell RNA-seq as a readout, we uncover reproducible phenotypic shifts induced by ligands that correlate with clinical features in larger datasets and are distinct from reference signatures available in public databases. In sum, our approach enables phenotypic screens that interrogate complex multicellular models with rich phenotypic readouts to advance translatable drug discovery as well as basic biology.

Exosomes derived from M1 macrophages inhibit the proliferation of the A549 and H1299 lung cancer cell lines via the miRNA-let-7b-5p-GNG5 axis

Background

Almost all cells are capable of secreting exosomes (Exos) for intercellular communication and regulation. Therefore, Exos can be used as a natural therapeutic platform to regulate genes or deliver drugs to treat diseases. M1 macrophages inhibit tumor growth by releasing pro-inflammatory factors. This study explored the applicability of M1 macrophage exosomes (M1-Exos) as gene carriers and the effects on GNG5 protein, and further examined whether macrophage repolarization could inhibit tumor activity.

Methods

M0 macrophages were polarized toward M1 using vitexin. Exos were obtained from M1 macrophages by ultra-centrifugation. The transwell non-contact co-culture system was used to co-culture M1 macrophages with HLF-α human lung epithelial cells or A549 or H1299 lung cancer cells. MTT, scratch, and transwell assays were used to detect the cell viability, migration, and invasion ability of cells in the four groups. Flow cytometry was used to detect the apoptosis rate of each group, and western blot (WB) analysis was performed to detect the change in the expression of proliferation- and apoptosis-related proteins. We screened the differentially expressed microRNAs using quantitative polymerase chain reaction technology. Luciferase reporter analysis was performed to explore the interaction between miRNA and protein. We used Xenografted A549 tumors in nude mice to study the effect of M1-Exos on tumor cell growth in vivo.

Results

The results showed that, under the M1 macrophage co-culture system, lung cancer cell viability, invasion, and migration ability decreased, and the number of apoptotic cells increased, will all indicators being statistically significant (P < 0.05). The expression levels of PCNA, KI67, and Bcl-2 decreased significantly, but that of Bax increased (P < 0.05). Exosomes can have the same effect on tumor cells as M1 macrophages. Exosomes can transport miR-let-7b-5p to tumor cells, and miR-let-7b-5p can inhibit tumor cell proliferation and promote tumor cell apoptosis by regulating the GNG5 protein level.

Conclusions

M1-Exos inhibit the proliferation, invasion, and metastasis of lung cancer cells through miRNA-let-7b-5p and GNG5 signaling pathways and inhibit the anti-apoptotic ability of lung cancer cells.

Refining the Treatment of Pancreatic Cancer From Big Data to Improved Individual Survival

Pancreatic cancer is one of the most lethal cancers worldwide, most notably in Europe and North America. Great strides have been made in combining the most effective conventional therapies to improve survival at least in the short and medium term. The start of treatment can only be made once a diagnosis is made, which at this point, the tumor volume is already very high in the primary cancer and systemically. If caught at the earliest opportunity (in circa 20% patients) surgical resection of the primary followed by combination chemotherapy can achieve 5-year overall survival rates of 30%-50%. A delay in detection of even a few months after symptom onset will result in the tumor having only borderline resectabilty (in 20%-30% of patients), in which case the best survival is achieved by using short-course chemotherapy before tumor resection as well as adjuvant chemotherapy. Once metastases become visible (in 40%-60% of patients), cure is not possible, palliative cytotoxics only being able to prolong life by few months. Even in apparently successful therapy in resected and borderline resectable patients, the recurrence rate is very high. Considerable efforts to understand the nature of pancreatic cancer through large-scale genomics, transcriptomics, and digital profiling, combined with functional preclinical models, using genetically engineered mouse models and patient derived organoids, have identified the critical role of the tumor microenvironment in determining the nature of chemo- and immuno-resistance. This functional understanding has powered fresh and exciting approaches for the treatment of this cancer.

AP1/Fra1 confers resistance to MAPK cascade inhibition in pancreatic cancer

Targeting KRAS downstream signaling remains an important therapeutic approach in pancreatic cancer. We used primary pancreatic ductal epithelial cells and mouse models allowing the conditional expression of oncogenic Kras^G12D, to investigate KRAS signaling integrators. We observed that the AP1 family member FRA1 is tightly linked to the KRAS signal and expressed in pre-malignant lesions and the basal-like subtype of pancreatic cancer. However, genetic-loss-of-function experiments revealed that FRA1 is dispensable for Kras^G12D-induced pancreatic cancer development in mice. Using FRA1 gain- and loss-of-function models in an unbiased drug screen, we observed that FRA1 is a modulator of the responsiveness of pancreatic cancer to inhibitors of the RAF-MEK-ERK cascade. Mechanistically, context-dependent FRA1-associated adaptive rewiring of oncogenic ERK signaling was observed and correlated with sensitivity to inhibitors of canonical KRAS signaling. Furthermore, pharmacological-induced degradation of FRA1 synergizes with MEK inhibitors. Our studies establish FRA1 as a part of the molecular machinery controlling sensitivity to MAPK cascade inhibition allowing the development of mechanism-based therapies.

Clinical diagnosis and management of pancreatic cancer: Markers, molecular mechanisms, and treatment options

Pancreatic cancer (PC) is the third-leading cause of cancer deaths. The overall 5-year survival rate of PC is 9%, and this rate for metastatic PC is below 3%. However, the PC-induced death cases will increase about 2-fold by 2060. Many factors such as genetic and environmental factors and metabolic diseases can drive PC development and progression. The most common type of PC in the clinic is pancreatic ductal adenocarcinoma, comprising approximately 90% of PC cases. Multiple pathogenic processes including but not limited to inflammation, fibrosis, angiogenesis, epithelial-mesenchymal transition, and proliferation of cancer stem cells are involved in the initiation and progression of PC. Early diagnosis is essential for curable therapy, for which a combined panel of serum markers is very helpful. Although some mono or combined therapies have been approved by the United States Food and Drug Administration for PC treatment, current therapies have not shown promising outcomes. Fortunately, the development of novel immunotherapies, such as oncolytic viruses-mediated treatments and chimeric antigen receptor-T cells, combined with therapies such as neoadjuvant therapy plus surgery, and advanced delivery systems of immunotherapy will improve therapeutic outcomes and combat drug resistance in PC patients. Herein, the pathogenesis, molecular signaling pathways, diagnostic markers, prognosis, and potential treatments in completed, ongoing, and recruiting clinical trials for PC were reviewed.

Mechanisms of PDAC subtype heterogeneity and therapy response

Pancreatic ductal adenocarcinoma (PDAC) is clinically challenging due to late diagnosis and resistance to therapy. Two major PDAC subtypes have been defined based on malignant epithelial cell gene expression profiles; the basal-like/squamous subtype is associated with a worse prognosis and therapeutic resistance as opposed to the classical subtype. Subtype specification is not binary, consistent with plasticity of malignant cell phenotype. PDAC heterogeneity and plasticity reflect partly malignant cell-intrinsic transcriptional and epigenetic regulation. However, the stromal and immune compartments of the tumor microenvironment (TME) also determine disease progression and therapy response. It is evident that integration of intrinsic and extrinsic factors can dictate subtype heterogeneity, and thus, delineating the pathways involved can help to reprogram PDAC towards a classical/druggable subtype.

Epigenetics in Pancreatic Ductal Adenocarcinoma: Impact on Biology and Utilization in Diagnostics and Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with high potential of metastases and therapeutic resistance. Although genetic mutations drive PDAC initiation, they alone do not explain its aggressive nature. Epigenetic mechanisms, including aberrant DNA methylation and histone modifications, significantly contribute to inter- and intratumoral heterogeneity, disease progression and metastasis. Thus, increased understanding of the epigenetic landscape in PDAC could offer new potential biomarkers and tailored therapeutic approaches. In this review, we shed light on the role of epigenetic modifications in PDAC biology and on the potential clinical applications of epigenetic biomarkers in liquid biopsy. In addition, we provide an overview of clinical trials assessing epigenetically targeted treatments alone or in combination with other anticancer therapies to improve outcomes of patients with PDAC.

Targeting TNF-α-producing macrophages activates antitumor immunity in pancreatic cancer via IL-33 signaling

Pancreatic ductal adenocarcinoma (PDA) remains resistant to immune therapies, largely owing to robustly fibrotic and immunosuppressive tumor microenvironments. It has been postulated that excessive accumulation of immunosuppressive myeloid cells influences immunotherapy resistance, and recent studies targeting macrophages in combination with checkpoint blockade have demonstrated promising preclinical results. Yet our understanding of tumor-associated macrophage (TAM) function, complexity, and diversity in PDA remains limited. Our analysis reveals significant macrophage heterogeneity, with bone marrow-derived monocytes serving as the primary source for immunosuppressive TAMs. These cells also serve as a primary source of TNF-α, which suppresses expression of the alarmin IL-33 in carcinoma cells. Deletion of Ccr2 in genetically engineered mice decreased monocyte recruitment, resulting in profoundly decreased TNF-α and increased IL-33 expression, decreased metastasis, and increased survival. Moreover, intervention studies targeting CCR2 with a new orthosteric inhibitor (CCX598) rendered PDA susceptible to checkpoint blockade, resulting in reduced metastatic burden and increased survival. Our data indicate that this shift in antitumor immunity is influenced by increased levels of IL-33, which increases dendritic cell and cytotoxic T cell activity. These data demonstrate that interventions to disrupt infiltration of immunosuppressive macrophages, or their signaling, have the potential to overcome barriers to effective immunotherapeutics for PDA.

Clinical Strategies Targeting the Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma

Pancreatic cancer has a complex tumor microenvironment which engages in extensive crosstalk between cancer cells, cancer-associated fibroblasts, and immune cells. Many of these interactions contribute to tumor resistance to anti-cancer therapies. Here, new therapeutic strategies designed to modulate the cancer-associated fibroblast and immune compartments of pancreatic ductal adenocarcinomas are described and clinical trials of novel therapeutics are discussed. Continued advances in our understanding of the pancreatic cancer tumor microenvironment are generating stromal and immune-modulating therapeutics that may improve patient responses to anti-tumor treatment.

Axon guidance receptor ROBO3 modulates subtype identity and prognosis via AXL-associated inflammatory network in pancreatic cancer

Metastatic pancreatic cancer (PDAC) has a poor clinical outcome with a 5-year survival rate below 3%. Recent transcriptome profiling of PDAC biopsies has identified 2 clinically distinct subtypes - the "basal-like" (BL) subtype with poor prognosis and therapy resistance compared with the less aggressive and drug-susceptible "classical" (CLA) subtype. However, the mechanistic events and environmental factors that promote the BL subtype identity are not very clear. Using preclinical models, patient-derived xenografts, and FACS-sorted PDAC patient biopsies, we report here that the axon guidance receptor, roundabout guidance receptor 3 (ROBO3), promotes the BL metastatic program via a potentially unique AXL/IL-6/phosphorylated STAT3 (p-STAT3) regulatory axis. RNA-Seq identified a ROBO3-mediated BL-specific gene program, while tyrosine kinase profiling revealed AXL as the key mediator of the p-STAT3 activation. CRISPR/dCas9-based ROBO3 silencing disrupted the AXL/p-STAT3 signaling axis, thereby halting metastasis and enhancing therapy sensitivity. Transcriptome analysis of resected patient tumors revealed that AXLhi neoplastic cells associated with the inflammatory stromal program. Combining AXL inhibitor and chemotherapy substantially restored a CLA phenotypic state and reduced disease aggressiveness. Thus, we conclude that a ROBO3-driven hierarchical network determines the inflammatory and prometastatic programs in a specific PDAC subtype.

Acute or chronic inflammation role in gastrointestinal oncology

The following letter to the editor highlights the review titled “Inflammatory bowel disease-related colorectal cancer: Past, present and future perspectives” in World J Gastrointest Oncol 2022 March 15; 14(3): 547-567. It is necessary to explore the role of inflammation in promoting tumorigenesis and development of gastrointestinal cancers.

TP53-Status-Dependent Oncogenic EZH2 Activity in Pancreatic Cancer

Simple Summary

Epigenetic alterations contribute to the aggressiveness and therapy resistance of Pancreatic Ductal Adenocarcinoma (PDAC). However, epigenetic regulators, including Enhancer of Zeste Homolog 2 (EZH2), reveal a strong context-dependent activity. Our study aimed to examine the context-defining molecular prerequisites of oncogenic EZH2 activity in PDAC to assess the therapeutic efficacy of targeting EZH2. Our preclinical study using diverse PDAC models demonstrates that the TP53 status determines oncogenic EZH2 activity. Only in TP53-wildtype (wt) PDAC subtypes was EZH2 blockade associated with a favorable PDAC prognosis mainly through cell-death response. We revealed that EZH2 depletion increases p53wt stability by the de-repression of CDKN2A. Therefore, our study provides preclinical evidence that an intact CDKN2A-p53wt axis is indispensable for a beneficial outcome of EZH2 depletion and highlights the significance of molecular stratification to improve epigenetic targeting in PDAC.

Abstract

Pancreatic Ductal Adenocarcinoma (PDAC) represents a lethal malignancy with a consistently poor outcome. Besides mutations in PDAC driver genes, the aggressive tumor biology of the disease and its remarkable therapy resistance are predominantly installed by potentially reversible epigenetic dysregulation. However, epigenetic regulators act in a context-dependent manner with opposing implication on tumor progression, thus critically determining the therapeutic efficacy of epigenetic targeting. Herein, we aimed at exploring the molecular prerequisites and underlying mechanisms of oncogenic Enhancer of Zeste Homolog 2 (EZH2) activity in PDAC progression. Preclinical studies in EZH2 proficient and deficient transgenic and orthotopic in vivo PDAC models and transcriptome analysis identified the TP53 status as a pivotal context-defining molecular cue determining oncogenic EZH2 activity in PDAC. Importantly, the induction of pro-apoptotic gene signatures and processes as well as a favorable PDAC prognosis upon EZH2 depletion were restricted to p53 wildtype (wt) PDAC subtypes. Mechanistically, we illustrate that EZH2 blockade de-represses CDKN2A transcription for the subsequent posttranslational stabilization of p53wt expression and function. Together, our findings suggest an intact CDKN2A-p53wt axis as a prerequisite for the anti-tumorigenic consequences of EZH2 depletion and emphasize the significance of molecular stratification for the successful implementation of epigenetic targeting in PDAC.

Organoids at the PUB: The Porcine Urinary Bladder Serves as a Pancreatic Niche for Advanced Cancer Modeling

Despite intensive research and progress in personalized medicine, pancreatic ductal adenocarcinoma remains one of the deadliest cancer entities. Pancreatic duct-like organoids (PDLOs) derived from human pluripotent stem cells (PSCs) or pancreatic cancer patient-derived organoids (PDOs) provide unique tools to study early and late stage dysplasia and to foster personalized medicine. However, such advanced systems are neither rapidly nor easily accessible and require an in vivo niche to study tumor formation and interaction with the stroma. Here, the establishment of the porcine urinary bladder (PUB) is revealed as an advanced organ culture model for shaping an ex vivo pancreatic niche. This model allows pancreatic progenitor cells to enter the ductal and endocrine lineages, while PDLOs further mature into duct-like tissue. Accordingly, the PUB offers an ex vivo platform for earliest pancreatic dysplasia and cancer if PDLOs feature KRASG12D mutations. Finally, it is demonstrated that PDOs-on-PUB i) resemble primary pancreatic cancer, ii) preserve cancer subtypes, iii) enable the study of niche epithelial crosstalk by spiking in pancreatic stellate and immune cells into the grafts, and finally iv) allow drug testing. In summary, the PUB advances the existing pancreatic cancer models by adding feasibility, complexity, and customization at low cost and high flexibility.

Pancreatic Organoids for Regenerative Medicine and Cancer Research

In recent years, the development of ex vivo organoid cultures has gained substantial attention as a model to study regenerative medicine and diseases in several tissues. Diabetes and pancreatic ductal adenocarcinoma (PDAC) are the two major devastating diseases affecting the pancreas. Suitable models for regenerative medicine in diabetes and to accurately study PDAC biology and treatment response are essential in the pancreatic field. Pancreatic organoids can be generated from healthy pancreas or pancreatic tumors and constitute an important translational bridge between in vitro and in vivo models. Here, we review the rapidly emerging field of pancreatic organoids and summarize the current applications of the technology to tissue regeneration, disease modelling, and drug screening.

NLRP3 activation in tumor-associated macrophages enhances lung metastasis of pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and is highly malignant due to its late diagnosis and early metastasis. Lung metastasis of PDAC occurs in a significant number of diagnosed patients and represents high severity of disease and poor clinical outcome. However, the molecular regulation of lung metastasis of PDAC is still not fully understood. Tumor-associated macrophages (TAMs) have recently been found to play an important role in cancer initiation, proliferation, progression, and metastasis. The proliferation, differentiation, and polarization of macrophages has been shown to be regulated by interleukin 1β (IL-1β), which is generated by NLR family pyrin domain containing 3 (NLRP3)-induced formation of inflammasome. Herein we investigated whether NLRP3 plays a role in lung metastasis of PDAC through regulation of macrophage polarization.

METHODS

Gene profiles for NLRP3 (+/+) and NLRP3 (-/-) macrophages obtained from the Gene Expression Omnibus (GEO) public database were compared and analyzed for altered genes related to macrophage polarization. The regulation of macrophage polarization by NLRP3 was examined in a coculture system with naïve NLRP3 (+/+) or NLRP3 (-/-) macrophages and PDAC cells. Cell growth was analyzed by a Cell Counting Kit-8 (CCK-8) assay. Cell invasiveness and migratory potential were analyzed by transwell cell invasion assay and cell migration assay, respectively. PDAC formation and lung metastasis were analyzed in a mouse model of PDAC with and without NLRP3 knockout.

RESULTS

GEO database analysis revealed significant alteration in genes that regulate macrophage polarization in NLRP3-depleted macrophages. NLRP3-depletion in macrophages seemed to favor an M1/M2b polarization. In vitro, the presence of NLRP3 in macrophages led to M2a/c/d TAM-like polarization when they were cocultured with PDAC cells. Conversely, NLRP3 depletion in macrophages led to M1/M2b polarization when they were cocultured with PDAC cells. NLRP3-depletion significantly inhibited tumor growth and stage progression in a mouse model of PDAC and significantly reduced the occurrence of lung metastasis.

CONCLUSIONS

Our results suggested that NLRP3 activation in TAM enhanced lung metastasis of PDAC through regulation of TAM polarization.