IL1-Induced JAK/STAT Signaling Is Antagonized by TGFβ to Shape CAF Heterogeneity in Pancreatic Ductal Adenocarcinoma

New perspectives in cancer immunotherapy: targeting IL-6 cytokine family

Chronic inflammation has been recognized as a canonical cancer hallmark. It is orchestrated by cytokines, which are master regulators of the tumor microenvironment (TME) as they represent the main communication bridge between cancer cells, the tumor stroma, and the immune system. Interleukin (IL)-6 represents a keystone cytokine in the link between inflammation and cancer. Many cytokines from the IL-6 family, which includes IL-6, oncostatin M, leukemia inhibitory factor, IL-11, IL-27, IL-31, ciliary neurotrophic factor, cardiotrophin 1, and cardiotrophin-like cytokine factor 1, have been shown to elicit tumor-promoting roles by modulating the TME, making them attractive therapeutic targets for cancer treatment.The development of immune checkpoint blockade (ICB) immunotherapies has radically changed the outcome of some cancers including melanoma, lung, and renal, although not without hurdles. However, ICB shows limited efficacy in other solid tumors. Recent reports support that chronic inflammation and IL-6 cytokine signaling are involved in resistance to immunotherapy. This review summarizes the available preclinical and clinical data regarding the implication of IL-6-related cytokines in regulating the immune TME and the response to ICB. Moreover, the potential clinical benefit of combining ICB with therapies targeting IL-6 cytokine members for cancer treatment is discussed.

Autocrine IL-6 drives cell and extracellular matrix anisotropy in scar fibroblasts

Fibrosis is associated with dramatic changes in extracellular matrix (ECM) architecture of unknown etiology. Here we exploit keloid scars as a paradigm to understand fibrotic ECM organization. We reveal that keloid patient fibroblasts uniquely produce a globally aligned ECM network in 2-D culture as observed in scar tissue. ECM anisotropy develops after rapid initiation of a fibroblast supracellular actin network, suggesting that cell alignment initiates ECM patterning. Keloid fibroblasts produce elevated levels of IL-6, and autocrine IL-6 production is both necessary and sufficient to induce cell and ECM alignment, as evidenced by ligand stimulation of normal dermal fibroblasts and treatment of keloid fibroblasts with the function blocking IL-6 receptor monoclonal antibody, tocilizumab. Downstream of IL-6, supracellular organization of keloid fibroblasts is controlled by activation of cell-cell adhesion. Adhesion formation inhibits contact-induced cellular overlap leading to nematic organization of cells and an alignment of focal adhesions. Keloid fibroblasts placed on isotropic ECM align the pre-existing matrix, suggesting that focal adhesion alignment leads to active anisotropic remodeling. These results show that IL-6-induced fibroblast cooperativity can control the development of a nematic ECM, highlighting both IL-6 signaling and cell-cell adhesions as potential therapeutic targets to inhibit this common feature of fibrosis.

Self-Adaptive Nanoregulator to Mitigate Dynamic Immune Evasion of Pancreatic Cancer

The advance of immunotherapy has shifted the paradigm of cancer management in clinics. Nevertheless, a considerable subset of pancreatic ductal adenocarcinoma (PDAC) patients marginally respond to current immunotherapy due to the occurrence of dynamic immune evasion arising from intrinsic and therapeutic stress. In this investigation, the pivotal role of pancreatic cancer-associated fibroblast (CAF)-induced fibrosis and tumor cell-mediated T-cell exhaustion in driving the dynamic immune evasion is identified. Building upon this discovery, the authors herein engineer a novel peptide-drug conjugate (PDC)-based self-adaptive nanoregulator for mitigating dynamic immune evasion of PDAC. The resulting nanoregulator can perform a two-stage morphology transformation from spherical micelle to nanofiber, and subsequently from nanofiber to spherical nanoparticles. Such kind of nanostructure design can facilitate differentialized delivery of CAF inhibitor in the extracellular matrix for intervening CAF-mediated tumor fibrosis, and indoleamine 2,3-dioxygenase 1 inhibitor to tumor cells for relieving IDO1-kynurenine axis-induced T-cell exhaustion. Antitumor study with the self-adaptive nanoregulator elicited persistent antitumor immunity and remarkable antitumor performance in both Panc02 and KPC tumor models in vivo. Taken together, the PDC-based self-adaptive nanoregulator may provide a novel avenue for enhanced PDAC immunotherapy.

Adipose-enriched peri-tumoral stroma, in contrast to myofibroblast-enriched stroma, prognosticates poorer survival in breast cancers

Despite our understanding of the genetic basis of intra-tumoral heterogeneity, the role of stromal heterogeneity arising from an altered tumor microenvironment in affecting tumorigenesis is poorly understood. In particular, extensive study on the peri-tumoral stroma in the morphologically normal tissues surrounding the tumor is lacking. Here, we examine the heterogeneity in tumors and peri-tumoral stroma from 8 ER+/PR+/HER2- invasive breast carcinomas, through multi-region transcriptomic profiling by microarray. We describe the regional heterogeneity observed at the intrinsic molecular subtype, pathway enrichment, and cell type composition levels within each tumor and its peri-tumoral region, up to 7 cm from the tumor margins. Moreover, we identify a pro-inflammatory adipose-enriched peri-tumoral subtype which was significantly associated with poorer overall survival in breast cancer patients, in contrast to an adaptive immune cell- and myofibroblast-enriched subtype. These data together suggest that peri-tumoral heterogeneity may be an important determinant of the evolution and treatment of breast cancers.

The cancer-immunity cycle: Indication, genotype, and immunotype

The cancer-immunity cycle provides a framework to understand the series of events that generate anti-cancer immune responses. It emphasizes the iterative nature of the response where the killing of tumor cells by T cells initiates subsequent rounds of antigen presentation and T cell stimulation, maintaining active immunity and adapting it to tumor evolution. Any step of the cycle can become rate-limiting, rendering the immune system unable to control tumor growth. Here, we update the cancer-immunity cycle based on the remarkable progress of the past decade. Understanding the mechanism of checkpoint inhibition has evolved, as has our view of dendritic cells in sustaining anti-tumor immunity. We additionally account for the role of the tumor microenvironment in facilitating, not just suppressing, the anti-cancer response, and discuss the importance of considering a tumor's immunological phenotype, the "immunotype". While these new insights add some complexity to the cycle, they also provide new targets for research and therapeutic intervention.

Exosomes-mediated transfer of LINC00691 regulates the formation of CAFs and promotes the progression of gastric cancer

OBJECTIVE

Gastric cancer (GC) is one of the malignant tumors with the highest mortality worldwide. Our previous studies have revealed that LINC00691 is up-regulated in serum of GC patients as a novel potential biomarker for GC diagnosis and prognosis. However, the roles of serum exosomal LINC00691 in GC has not been clarified. This study aimed to find the expression pattern of serum exosomal LINC00691 in GC patients and the correlation between the level of serum exosomal LINC00691 and the pathology of gastric cancer patients.

METHODS

We collected the serum of 94 GC patients before surgery and extracted exosomes to detect the expression level of exosomal LINC00691, with 21 healthy volunteers and 17 patients with benign gastric diseases as controls. Surgical GC tissues and paired healthy tissues were collected to culture primary cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs). We then treated NFs with LINC00691-rich GC cell culture supernatant or exosomes and detected the activation markers and biological functions of the fibroblasts.

RESULTS

The results of real-time qPCR indicated that the serum exosomal LINC00691 of GC patients was significantly higher than that of healthy subjects and patients with benign gastric diseases, and was associated with the clinicopathology of GC patients. More interestingly, when the NFs were treated with GC exosomes, the level of LINC00691 was significantly increased, the cell proliferation and migration were noticeably enhanced, and the ability to accelerate GC cell proliferation and invasion was promoted, which means that the induced fibroblasts gained the properties of CAFs. In addition, we found that knockdown of LINC00691 and the use of the JAK2/STAT3 signaling pathway inhibitor ruxolitinib effectively deprived exosome-containing GC cell supernatants of the effects on NFs.

CONCLUSION

Our study suggested that exosomal LINC00691 promoted NFs to gained the properties of CAFs depending on JAK2/STAT3 signaling pathway as a potential diagnostic biomarker for GC.

Normal Uterine Fibroblast Are Reprogramed into Ovarian Cancer-Associated Fibroblasts by Ovarian Tumor-derived Conditioned Media

Cancer-associated fibroblasts (CAFs) are key contributors to ovarian cancer (OC) progression and therapeutic resistance through dysregulation of the extracellular matrix (ECM). CAFs are a heterogenous population derived from different cell types through activation and reprogramming. Current studies rely on uncharacterized heterogenous primary CAFs or normal fibroblasts that fail to recapitulate CAF-like tumor behavior. Here, we present a translatable-based approach for the reprogramming of normal uterine fibroblasts into ovarian CAFs using ovarian tumor-derived conditioned media to establish two well-characterized ovarian conditioned CAF lines. Phenotypic and functional characterization demonstrated that the conditioned CAFs expressed a CAF-like phenotype, strengthened proliferation, secretory, contractility, and ECM remodeling properties when compared to resting normal fibroblasts, consistent with an activated fibroblast status. Moreover, conditioned CAFs significantly enhanced drug resistance and tumor progression and resembled a CAF-like subtype associated with worse prognosis. The present study provides a reproducible, cost-effective, and clinically relevant protocol to reprogram normal fibroblasts into CAFs using tumor-derived conditioned media. Using these resources, further development of therapeutics that possess potentiality and specificity towards CAF-mediated chemoresistance in OC are further warranted.

A comprehensive analysis of tumor-stromal collagen in relation to pathological, molecular, and immune characteristics and patient survival in pancreatic ductal adenocarcinoma

BACKGROUND

Abundant collagen deposition is a hallmark of pancreatic ductal adenocarcinomas (PDACs). This study clarified the interactive relationship between tumor-stromal collagen, molecular and immune characteristics, and tumor pr ogression in human PDAC.

METHODS

We performed a comprehensive examination using an integrative molecular pathological epidemiology database on 169 cases with resected PDAC . The amount of tumor-stromal collagen was quantified through digital imaging analysis for Elastica van Gieson-stained whole-section tumor slides. We analyzed the association of tumor-stromal collagen with gene alterations (KRAS, TP53, CDKN2A/p16, and SMAD4), immune parameters (CD4+ tumor-infiltrating lymphocytes [TILs], CD8+ TILs, FOXP3+ TILs, and tertiary lymphoid structures), and patient prognosis.

RESULTS

Low amounts of tumor-stromal collagen were associated with poor differentiation (multivariable OR = 3.82, 95%CI = 1.41-12.2, P = 0.008) and CDKN2A/p16 alteration (OR [95%CI] = 2.06 [1.08-4.02], P = 0.03). Tumors with low collagen levels had shorter overall survival (HR [95%CI] = 2.38 [1.59-3.56], P < 0.0001). In the S-1 and gemcitabine (GEM) treatment groups, low tumor-stromal collagen was linked to poor prognosis of patients with PDAC (S-1 group: multivariable HR [95%CI] = 2.76 [1.36-5.79], P = 0.005; GEM group: multivariate HR [95%CI] = 2.91 [1.34-6.71], P = 0.007). Additionally, low amounts of tumor-stromal collagen were also linked to low levels of CD4+ TILs (P = 0.046), CD8+ TILs (P = 0.09), and tertiary lymphoid structures (P = 0.001).

CONCLUSIONS

Tumor-stromal collagen deposition may play a crucial role in modulating tumor-immune microenvironment and determining response to adjuvant chemotherapy and patient survival outcomes.

The Interaction between Macrophages and Triple-negative Breast Cancer Cells Induces ROS-Mediated Interleukin 1α Expression to Enhance Tumorigenesis and Metastasis

Triple-negative breast cancer (TNBC) has higher mortality than non-TNBC because of its stronger metastatic capacity. Increasing studies reported that TNBC tumors had more macrophage infiltration than non-TNBC tumors, which promoted the metastasis of TNBC cells. However, how TNBC cells become more malignant after interacting with macrophages is less reported. In this study, it is observed that when TNBC cells are co-cultured with macrophages, they display higher viability and stronger metastatic ability than non-TNBC cells. Mechanistic studies reveal that TNBC cells acquired these abilities via interactions with macrophages in three phases. First, within 12 h of co-culture with macrophages, some TNBC cells have significantly elevated levels of reactive oxygen species (ROS), which upregulate interleukin 1α (IL1α) expression in ERK1/2-c-Jun- and NF-κB-dependent manners at 24-48 h. Second, the secreted IL1α bound to IL1R1 activates the ERK1/2-ZEB1-VIM pathway which increases metastasis. Third, IL1α/IL1R1 facilitates its own synthesis and induces the expression of IL1β and IL8 at 72-96 h through the MKK4-JNK-c-Jun and NF-κB signaling pathways. Moreover, a higher level of IL1α is positively correlated with more macrophage infiltration and shorter overall survival in breast cancer patients. Thus, reducing ROS elevation or downregulating IL1α expression can serve as new strategies to decrease metastasis of TNBC.

Transforming Growth Factor-β Blockade in Pancreatic Cancer Enhances Sensitivity to Combination Chemotherapy

BACKGROUND & AIMS

Transforming growth factor-b (TGFb) plays pleiotropic roles in pancreatic cancer, including promoting metastasis, attenuating CD8 T-cell activation, and enhancing myofibroblast differentiation and deposition of extracellular matrix. However, single-agent TGFb inhibition has shown limited efficacy against pancreatic cancer in mice or humans.

METHODS

We evaluated the TGFβ-blocking antibody NIS793 in combination with gemcitabine/nanoparticle (albumin-bound)-paclitaxel or FOLFIRINOX (folinic acid [FOL], 5-fluorouracil [F], irinotecan [IRI] and oxaliplatin [OX]) in orthotopic pancreatic cancer models. Single-cell RNA sequencing and immunofluorescence were used to evaluate changes in tumor cell state and the tumor microenvironment.

RESULTS

Blockade of TGFβ with chemotherapy reduced tumor burden in poorly immunogenic pancreatic cancer, without affecting the metastatic rate of cancer cells. Efficacy of combination therapy was not dependent on CD8 T cells, because response to TGFβ blockade was preserved in CD8-depleted or recombination activating gene 2 (RAG2-/-) mice. TGFβ blockade decreased total α-smooth muscle actin-positive fibroblasts but had minimal effect on fibroblast heterogeneity. Bulk RNA sequencing on tumor cells sorted ex vivo revealed that tumor cells treated with TGFβ blockade adopted a classical lineage consistent with enhanced chemosensitivity, and immunofluorescence for cleaved caspase 3 confirmed that TGFβ blockade increased chemotherapy-induced cell death in vivo.

CONCLUSIONS

TGFβ regulates pancreatic cancer cell plasticity between classical and basal cell states. TGFβ blockade in orthotropic models of pancreatic cancer enhances sensitivity to chemotherapy by promoting a classical malignant cell state. This study provides scientific rationale for evaluation of NIS793 with FOLFIRINOX or gemcitabine/nanoparticle (albumin-bound) paclitaxel chemotherapy backbone in the clinical setting and supports the concept of manipulating cancer cell plasticity to increase the efficacy of combination therapy regimens.

Friend or foe? The elusive role of hepatic stellate cells in liver cancer

Liver fibrosis is a substantial risk factor for the development and progression of liver cancer, which includes hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Studies utilizing cell fate mapping and single-cell transcriptomics techniques have identified quiescent perisinusoidal hepatic stellate cells (HSCs) as the primary source of activated collagen-producing HSCs and liver cancer-associated fibroblasts (CAFs) in HCC and liver metastasis, complemented in iCCA by contributions from portal fibroblasts. At the same time, integrative computational analysis of single-cell, single-nucleus and spatial RNA sequencing data have revealed marked heterogeneity among HSCs and CAFs, with distinct subpopulations displaying unique gene expression signatures and functions. Some of these subpopulations have divergent roles in promoting or inhibiting liver fibrogenesis and carcinogenesis. In this Review, we discuss the dual roles of HSC subpopulations in liver fibrogenesis and their contribution to liver cancer promotion, progression and metastasis. We review the transcriptomic and functional similarities between HSC and CAF subpopulations, highlighting the pathways that either promote or prevent fibrosis and cancer, and the immunological landscape from which these pathways emerge. Insights from ongoing studies will yield novel strategies for developing biomarkers, assessing prognosis and generating new therapies for both HCC and iCCA prevention and treatment.

Small Molecule Targeting Immune Cells: A Novel Approach for Cancer Treatment

Conventional and cancer immunotherapies encompass diverse strategies to address various cancer types and stages. However, combining these approaches often encounters limitations such as non-specific targeting, resistance development, and high toxicity, leading to suboptimal outcomes in many cancers. The tumor microenvironment (TME) is orchestrated by intricate interactions between immune and non-immune cells dictating tumor progression. An innovative avenue in cancer therapy involves leveraging small molecules to influence a spectrum of resistant cell populations within the TME. Recent discoveries have unveiled a phenotypically diverse cohort of innate-like T (ILT) cells and tumor hybrid cells (HCs) exhibiting novel characteristics, including augmented proliferation, migration, resistance to exhaustion, evasion of immunosurveillance, reduced apoptosis, drug resistance, and heightened metastasis frequency. Leveraging small-molecule immunomodulators to target these immune players presents an exciting frontier in developing novel tumor immunotherapies. Moreover, combining small molecule modulators with immunotherapy can synergistically enhance the inhibitory impact on tumor progression by empowering the immune system to meticulously fine-tune responses within the TME, bolstering its capacity to recognize and eliminate cancer cells. This review outlines strategies involving small molecules that modify immune cells within the TME, potentially revolutionizing therapeutic interventions and enhancing the anti-tumor response.

Inflammation-mediated fibroblast activation and immune dysregulation in collagen VII-deficient skin

Inflammation is known to play a critical role in all stages of tumorigenesis; however, less is known about how it predisposes the tissue microenvironment preceding tumor formation. Recessive dystrophic epidermolysis bullosa (RDEB), a skin-blistering disease secondary to COL7A1 mutations and associated with chronic wounding, inflammation, fibrosis, and cutaneous squamous cell carcinoma (cSCC), models this dynamic. Here, we used single-cell RNA sequencing (scRNAseq) to analyze gene expression patterns in skin cells from a mouse model of RDEB. We uncovered a complex landscape within the RDEB dermal microenvironment that exhibited altered metabolism, enhanced angiogenesis, hyperproliferative keratinocytes, infiltration and activation of immune cell populations, and inflammatory fibroblast priming. We demonstrated the presence of activated neutrophil and Langerhans cell subpopulations and elevated expression of PD-1 and PD-L1 in T cells and antigen-presenting cells, respectively. Unsupervised clustering within the fibroblast population further revealed two differentiation pathways in RDEB fibroblasts, one toward myofibroblasts and the other toward a phenotype that shares the characteristics of inflammatory fibroblast subsets in other inflammatory diseases as well as the IL-1-induced inflammatory cancer-associated fibroblasts (iCAFs) reported in various cancer types. Quantitation of inflammatory cytokines indicated dynamic waves of IL-1α, TGF-β1, TNF, IL-6, and IFN-γ concentrations, along with dermal NF-κB activation preceding JAK/STAT signaling. We further demonstrated the divergent and overlapping roles of these cytokines in inducing inflammatory phenotypes in RDEB patients as well as RDEB mouse-derived fibroblasts together with their healthy controls. In summary, our data have suggested a potential role of inflammation, driven by the chronic release of inflammatory cytokines such as IL-1, in creating an immune-suppressed dermal microenvironment that underlies RDEB disease progression.

Fibroblast diversity and plasticity in the tumor microenvironment: roles in immunity and relevant therapies

Cancer-associated fibroblasts (CAFs), enriched in the tumor stroma, have received increasing attention because of their multifaceted effects on tumorigenesis, development, metastasis, and treatment resistance in malignancies. CAFs contributed to suppressive microenvironment via different mechanisms, while CAFs also exerted some antitumor effects. Therefore, CAFs have been considered promising therapeutic targets for their remarkable roles in malignant tumors. However, patients with malignancies failed to benefit from current CAFs-targeted drugs in many clinical trials, which suggests that further in-depth investigation into CAFs is necessary. Here, we summarize and outline the heterogeneity and plasticity of CAFs mainly by exploring their origin and activation, highlighting the regulation of CAFs in the tumor microenvironment during tumor evolution, as well as the critical roles performed by CAFs in tumor immunity. In addition, we summarize the current immunotherapies targeting CAFs, and conclude with a brief overview of some prospects for the future of CAFs research in the end. Video Abstract.

The Critical Interplay of CAF Plasticity and Resistance in Prostate Cancer

Prostate cancer is a common malignancy driven by the androgen receptor (AR) pathway, with androgen deprivation therapy (ADT) being a standard treatment. However, the development of castration-resistant prostate cancer (CRPC) poses a significant challenge. CRPC is characterized by significantly increased tumor heterogeneity and lineage plasticity. Current research has primarily emphasized intrinsic tumor mechanisms, paying less attention to the role of the tumor microenvironment in cancer recurrence and drug resistance. In their recent study published in Cancer Cell, Wang and colleagues used single-cell RNA sequencing in genetically engineered mouse models with prostate tumors at different stages. They revealed that SPP1+ myofibroblastic cancer-associated fibroblasts (myCAF), induced by ADT, play an instrumental role in CRPC development. Their work also underscores the association between therapy-induced phenotypic alterations of CAFs and disease progression. This discovery highlights the potential for stromal compartment targeting as a means to mitigate CRPC development and overcome treatment resistance.

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

PURPOSE

This research investigates the association between benzodiazepines (BZD) and cancer patient survival outcomes, the pancreatic cancer tumor microenvironment, and cancer-associated fibroblast (CAF) signaling.

EXPERIMENTAL DESIGN

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.

RESULTS

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.

CONCLUSIONS

We demonstrate that LOR stimulates fibrosis and inflammatory signaling, promotes desmoplasia and ischemic necrosis, and is associated with decreased pancreatic cancer patient survival.

Pancreatic RECK inactivation promotes cancer formation, epithelial-mesenchymal transition, and metastasis

RECK is downregulated in various human cancers; however, how RECK inactivation affects carcinogenesis remains unclear. We addressed this issue in a pancreatic ductal adenocarcinoma (PDAC) mouse model and found that pancreatic Reck deletion dramatically augmented the spontaneous development of PDAC with a mesenchymal phenotype, which was accompanied by increased liver metastases and decreased survival. Lineage tracing revealed that pancreatic Reck deletion induced epithelial-mesenchymal transition (EMT) in PDAC cells, giving rise to inflammatory cancer-associated fibroblast-like cells in mice. Splenic transplantation of Reck-null PDAC cells resulted in numerous liver metastases with a mesenchymal phenotype, whereas reexpression of RECK markedly reduced metastases and changed the PDAC tumor phenotype into an epithelial one. Consistently, low RECK expression correlated with low E-cadherin expression, poor differentiation, metastasis, and poor prognosis in human PDAC. RECK reexpression in the PDAC cells was found to downregulate MMP2 and MMP3, with a concomitant increase in E-cadherin and decrease in EMT-promoting transcription factors. An MMP inhibitor recapitulated the effects of RECK on the expression of E-cadherin and EMT-promoting transcription factors and invasive activity. These results establish the authenticity of RECK as a pancreatic tumor suppressor, provide insights into its underlying mechanisms, and support the idea that RECK could be an important therapeutic effector against human PDAC.

Inhibiting Stromal Class I HDACs Curbs Pancreatic Cancer Progression

Oncogenic lesions in pancreatic ductal adenocarcinoma (PDAC) hijack the epigenetic machinery in stromal components to establish a desmoplastic and therapeutic resistant tumor microenvironment (TME). Here we identify Class I histone deacetylases (HDACs) as key epigenetic factors facilitating the induction of pro-desmoplastic and pro-tumorigenic transcriptional programs in pancreatic stromal fibroblasts. Mechanistically, HDAC-mediated changes in chromatin architecture enable the activation of pro-desmoplastic programs directed by serum response factor (SRF) and forkhead box M1 (FOXM1). HDACs also coordinate fibroblast pro-inflammatory programs inducing leukemia inhibitory factor (LIF) expression, supporting paracrine pro-tumorigenic crosstalk. HDAC depletion in cancer-associated fibroblasts (CAFs) and treatment with the HDAC inhibitor entinostat (Ent) in PDAC mouse models reduce stromal activation and curb tumor progression. Notably, HDAC inhibition (HDACi) enriches a lipogenic fibroblast subpopulation, a potential precursor for myofibroblasts in the PDAC stroma. Overall, our study reveals the stromal targeting potential of HDACi, highlighting the utility of this epigenetic modulating approach in PDAC therapeutics.

Extracellular vesicles promote activation of pro-inflammatory cancer-associated fibroblasts in oral cancer

Introduction: Oral squamous cell carcinoma (OSCC) is the most common form of head and neck cancer and has a survival rate of ∼50% over 5 years. New treatment strategies are sorely needed to improve survival rates-and a better understanding of the mechanisms underlying tumorigenesis is needed to develop these strategies. The role of the tumor microenvironment (TME) has increasingly been identified as crucial in tumor progression and metastasis. One of the main constituents of the TME, cancer-associated fibroblasts (CAFs), plays a key role in influencing the biological behavior of tumors. Multiple mechanisms contribute to CAF activation, such as TGFβ signaling, but the role of extracellular vesicles (EVs) in CAF activation in OSCC is poorly understood. Assessing the impact of oral cancer-derived EVs on CAF activation will help to better illuminate OSCC pathophysiology and may drive development of novel treatments options. Methods: EVs were isolated from OSCC cell lines (Cal 27, SCC-9, SCC-25) using differential centrifugation. Nanoparticle tracking analysis was used for EV characterization, and Western blot to confirm the presence of EV protein markers. Oral fibroblasts were co-cultured with enriched EVs, TGFβ, or PBS over 72 h to assess activation. Flow cytometry was used to evaluate CAF markers. RNA collected from fibroblasts was extracted and the transcriptome was sequenced. Conditioned media from the co-cultures was evaluated with cytokine array profiling. Results: OSCC-derived EVs can activate oral fibroblasts into CAFs that are different from those activated by TGFβ, suggesting different mechanisms of activation and different functional properties. Gene set enrichment analysis showed several upregulated inflammatory pathways in those CAFs exposed to OSCC-derived EVs. Marker genes for inflammatory CAF subtypes were also upregulated, but not in CAFs activated by TGFβ. Finally, cytokine array analysis on secreted proteins revealed elevated levels of several pro-inflammatory cytokines from EV-activated CAFs, for instance IL-8 and CXCL5. Discussion: Our results reveal the ability of OSCC-derived EVs to activate fibroblasts into CAFs. These CAFs seem to have unique properties, differing from TGFβ-activated CAFs. Gaining an understanding of the interplay between EVs and stromal cells such as CAFs could lead to further insights into OSCC tumorigenesis and potential novel therapeutics.

STAT3 is a genetic modifier of TGF-beta induced EMT in KRAS mutant pancreatic cancer

Oncogenic mutations in KRAS are among the most common in cancer. Classical models suggest that loss of epithelial characteristics and the acquisition of mesenchymal traits are associated with cancer aggressiveness and therapy resistance. However, the mechanistic link between these phenotypes and mutant KRAS biology remains to be established. Here we identify STAT3 as a genetic modifier of TGF-beta-induced epithelial to mesenchymal transition. Gene expression profiling of pancreatic cancer cells identifies more than 200 genes commonly regulated by STAT3 and oncogenic KRAS. Functional classification of STAT3 responsive program reveals its major role in tumor maintenance and epithelial homeostasis. The signatures of STAT3-activated cell states can be projected onto human KRAS mutant tumors, suggesting that they faithfully reflect characteristics of human disease. These observations have implications for therapeutic intervention and tumor aggressiveness.

Stromal cells in the tumor microenvironment: accomplices of tumor progression?

The tumor microenvironment (TME) is made up of cells and extracellular matrix (non-cellular component), and cellular components include cancer cells and non-malignant cells such as immune cells and stromal cells. These three types of cells establish complex signals in the body and further influence tumor genesis, development, metastasis and participate in resistance to anti-tumor therapy. It has attracted scholars to study immune cells in TME due to the significant efficacy of immune checkpoint inhibitors (ICI) and chimeric antigen receptor T (CAR-T) in solid tumors and hematologic tumors. After more than 10 years of efforts, the role of immune cells in TME and the strategy of treating tumors based on immune cells have developed rapidly. Moreover, ICI have been recommended by guidelines as first- or second-line treatment strategies in a variety of tumors. At the same time, stromal cells is another major class of cellular components in TME, which also play a very important role in tumor metabolism, growth, metastasis, immune evasion and treatment resistance. Stromal cells can be recruited from neighboring non-cancerous host stromal cells and can also be formed by transdifferentiation from stromal cells to stromal cells or from tumor cells to stromal cells. Moreover, they participate in tumor genesis, development and drug resistance by secreting various factors and exosomes, participating in tumor angiogenesis and tumor metabolism, regulating the immune response in TME and extracellular matrix. However, with the deepening understanding of stromal cells, people found that stromal cells not only have the effect of promoting tumor but also can inhibit tumor in some cases. In this review, we will introduce the origin of stromal cells in TME as well as the role and specific mechanism of stromal cells in tumorigenesis and tumor development and strategies for treatment of tumors based on stromal cells. We will focus on tumor-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), tumor-associated adipocytes (CAAs), tumor endothelial cells (TECs) and pericytes (PCs) in stromal cells.

Reprogramming of cancer-associated fibroblasts combined with immune checkpoint inhibitors: A potential therapeutic strategy for cancers

Activated fibroblasts, namely cancer-associated fibroblasts (CAFs), are highly heterogeneous in phenotypes, functions, and origins. CAFs originated from varieties of cell types, including local resident fibroblasts, epithelial cells, mesenchymal stromal cells, or others. These cells participate in tumor angiogenesis, mechanics, drug access, and immune suppression, with the latter being particularly important. It was difficult to distinguish CAFs by subsets due to their complex origins until the use of scRNA-seq. Reprogramming CAFs with TGFβ-RI inhibitor, a CXCR4 blocker, or other methods increases T cells activation and infiltration, together with a decrease in CAFs recruitment, thus improving the prognosis. As depletion of CAFs can't bring clinical benefit, the combination of reprogramming CAFs and immune checkpoint inhibitors (ICIs) come into consideration. It has shown better outcomes compared with monotherapy respectively in basic/preclinical researches, and needs more data on clinical trials. Combination therapy may be a promising and expecting method for treatment of cancer.

Mesenchymal-like Tumor Cells and Myofibroblastic Cancer-Associated Fibroblasts Are Associated with Progression and Immunotherapy Response of Clear Cell Renal Cell Carcinoma

Immune checkpoint inhibitors (ICI) represent the cornerstone for the treatment of patients with metastatic clear cell renal cell carcinoma (ccRCC). Despite a favorable response for a subset of patients, others experience primary progressive disease, highlighting the need to precisely understand the plasticity of cancer cells and their cross-talk with the microenvironment to better predict therapeutic response and personalize treatment. Single-cell RNA sequencing of ccRCC at different disease stages and normal adjacent tissue (NAT) from patients identified 46 cell populations, including 5 tumor subpopulations, characterized by distinct transcriptional signatures representing an epithelial-to-mesenchymal transition gradient and a novel inflamed state. Deconvolution of the tumor and microenvironment signatures in public data sets and data from the BIONIKK clinical trial (NCT02960906) revealed a strong correlation between mesenchymal-like ccRCC cells and myofibroblastic cancer-associated fibroblasts (myCAF), which are both enriched in metastases and correlate with poor patient survival. Spatial transcriptomics and multiplex immune staining uncovered the spatial proximity of mesenchymal-like ccRCC cells and myCAFs at the tumor-NAT interface. Moreover, enrichment in myCAFs was associated with primary resistance to ICI therapy in the BIONIKK clinical trial. These data highlight the epithelial-mesenchymal plasticity of ccRCC cancer cells and their relationship with myCAFs, a critical component of the microenvironment associated with poor outcome and ICI resistance.

SIGNIFICANCE

Single-cell and spatial transcriptomics reveal the proximity of mesenchymal tumor cells to myofibroblastic cancer-associated fibroblasts and their association with disease outcome and immune checkpoint inhibitor response in clear cell renal cell carcinoma.

Cancer-associated fibroblasts: Mediators of head and neck tumor microenvironment remodeling

Cancer-associated fibroblasts (CAFs) are involved in critical aspects of head and neck squamous cell carcinoma (HNSCC) pathogenesis, such as the formation of a tumor-permissive extracellular matrix structure, angiogenesis, or immune and metabolic reprogramming of the tumor microenvironment (TME), with implications for metastasis and resistance to radiotherapy and chemotherapy. The pleiotropic effect of CAFs in TME is likely to reflect the heterogeneity and plasticity of their population, with context-dependent effects on carcinogenesis. The specific properties of CAFs provide many targetable molecules that could play an important role in the future therapy of HNSCC. In this review article, we will focus on the role of CAFs in the TME of HNSCC tumors. We will also discuss clinically relevant agents targeting CAFs, their signals, and signaling pathways, which are activated by CAFs in cancer cells, with the potential for repurposing for HNSCC therapy.

Flourishing tumor organoids: History, emerging technology, and application

Malignant tumors are one of the leading causes of death which impose an increasingly heavy burden on all countries. Therefore, the establishment of research models that closely resemble original tumor characteristics is crucial to further understanding the mechanisms of malignant tumor development, developing safer and more effective drugs, and formulating personalized treatment plans. Recently, organoids have been widely used in tumor research owing to their advantages including preserving the structure, heterogeneity, and cellular functions of the original tumor, together with the ease of manipulation. This review describes the history and characteristics of tumor organoids and the synergistic combination of three-dimensional (3D) culture approaches for tumor organoids with emerging technologies, including tissue-engineered cell scaffolds, microfluidic devices, 3D bioprinting, rotating wall vessels, and clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9 (CRISPR-Cas9). Additionally, the progress in research and the applications in basic and clinical research of tumor organoid models are summarized. This includes studies of the mechanism of tumor development, drug development and screening, precision medicine, immunotherapy, and simulation of the tumor microenvironment. Finally, the existing shortcomings of tumor organoids and possible future directions are discussed.

Polysaccharides from Lentinus edodes prevent acquired drug resistance to docetaxel in prostate cancer cells by decreasing the TGF-β1 secretion of cancer-associated fibroblasts

Prostate cancer is one of the most prevalent lethal diseases among men globally. In the treatment of prostate cancer, the limited therapeutic efficacy of the standard non-hormonal systemic therapy docetaxel (DTX) represents an important challenge. Cancer-associated fibroblasts (CAFs) play a crucial role in resistance to therapy because of their prevalence and functional pleiotropy in tumor environments. Our previous research revealed that MPSSS, a novel polysaccharide extracted from Lentinus edodes, could significantly attenuate the immunosuppressive function of myeloid suppressor cells and CAFs. In this study, we investigated whether MPSSS could potentiate the efficacy of DTX against prostate cancer by inhibiting CAF-induced chemoresistance and elucidated its underlying mechanisms. The sensitivity of PC-3 prostate cancer cells cultured with conditioned medium derived from CAFs (CAF-CM) to DTX was assessed. The resistance effect induced by CAF-CM was abolished when CAFs were pretreated with MPSSS. Bioinformatic analysis of datasets from the Gene Expression Omnibus database revealed the activation of the transforming growth factor β1 (TGF-β1) signaling pathway in DTX-resistant cells. Based on this finding, we demonstrated that treatment with the TGF-β1 receptor inhibitor SB525334 reversed DTX resistance in CAFs, suggesting that TGF-β1 secreted by CAFs was a crucial intermediary in the development of DTX resistance in PC3 cells. Further research revealed that MPSSS decreases the secretion of TGF-β1 by inhibiting the JAK2/STAT3 pathway via Toll-like receptor 4 in CAFs. Overall, MPSSS might be a potential adjuvant treatment for DTX resistance in prostate cancer.

Coordinated single-cell tumor microenvironment dynamics reinforce pancreatic cancer subtype

Bulk analyses of pancreatic ductal adenocarcinoma (PDAC) samples are complicated by the tumor microenvironment (TME), i.e. signals from fibroblasts, endocrine, exocrine, and immune cells. Despite this, we and others have established tumor and stroma subtypes with prognostic significance. However, understanding of underlying signals driving distinct immune and stromal landscapes is still incomplete. Here we integrate 92 single cell RNA-seq samples from seven independent studies to build a reproducible PDAC atlas with a focus on tumor-TME interdependence. Patients with activated stroma are synonymous with higher myofibroblastic and immunogenic fibroblasts, and furthermore show increased M2-like macrophages and regulatory T-cells. Contrastingly, patients with 'normal' stroma show M1-like recruitment, elevated effector and exhausted T-cells. To aid interoperability of future studies, we provide a pretrained cell type classifier and an atlas of subtype-based signaling factors that we also validate in mouse data. Ultimately, this work leverages the heterogeneity among single-cell studies to create a comprehensive view of the orchestra of signaling interactions governing PDAC.

Methylation across the central dogma in health and diseases: new therapeutic strategies

The proper transfer of genetic information from DNA to RNA to protein is essential for cell-fate control, development, and health. Methylation of DNA, RNAs, histones, and non-histone proteins is a reversible post-synthesis modification that finetunes gene expression and function in diverse physiological processes. Aberrant methylation caused by genetic mutations or environmental stimuli promotes various diseases and accelerates aging, necessitating the development of therapies to correct the disease-driver methylation imbalance. In this Review, we summarize the operating system of methylation across the central dogma, which includes writers, erasers, readers, and reader-independent outputs. We then discuss how dysregulation of the system contributes to neurological disorders, cancer, and aging. Current small-molecule compounds that target the modifiers show modest success in certain cancers. The methylome-wide action and lack of specificity lead to undesirable biological effects and cytotoxicity, limiting their therapeutic application, especially for diseases with a monogenic cause or different directions of methylation changes. Emerging tools capable of site-specific methylation manipulation hold great promise to solve this dilemma. With the refinement of delivery vehicles, these new tools are well positioned to advance the basic research and clinical translation of the methylation field.

Novel CAF-identifiers via transcriptomic and protein level analysis in HNSC patients

Cancer-associated fibroblasts (CAFs), a prominent component of the tumor microenvironment, play an important role in tumor development, invasion, and drug resistance. The expression of distinct "CAF-markers" which separates CAFs from normal fibroblasts and epithelial cells, have traditionally been used to identify them. These commonly used CAF-markers have been reported to differ greatly across different CAF subpopulations, even within a cancer type. Using an unbiased -omic approach from public data and in-house RNAseq data from patient derived novel CAF cells, TIMP-1, SPARC, COL1A2, COL3A1 and COL1A1 were identified as potential CAF-markers by differential gene expression analysis using publicly available single cell sequencing data and in-house RNAseq data to distinguish CAF populations from tumor epithelia and normal oral fibroblasts. Experimental validation using qPCR and immunofluorescence revealed CAF-specific higher expression of TIMP-1 and COL1A2 as compared to other markers in 5 novel CAF cells, derived from patients of diverse gender, habits and different locations of head and neck squamous cell carcinoma (HNSC). Upon immunohistochemical (IHC) analysis of FFPE blocks however, COL1A2 showed better differential staining between tumor epithelia and tumor stroma. Similar data science driven approach utilizing single cell sequencing and RNAseq data from stabilized CAFs can be employed to identify CAF-markers in various cancers.

GREM1 signaling in cancer: tumor promotor and suppressor?

GREMLIN1 (GREM1) is member of a family of structurally and functionally related secreted cysteine knot proteins, which act to sequester and inhibit the action of multifunctional bone morphogenetic proteins (BMPs). GREM1 binds directly to BMP dimers, thereby preventing BMP-mediated activation of BMP type I and type II receptors. Multiple reports identify the overexpression of GREM1 as a contributing factor in a broad range of cancers. Additionally, the GREM1 gene is amplified in a rare autosomal dominant inherited form of colorectal cancer. The inhibitory effects of GREM1 on BMP signaling have been linked to these tumor-promoting effects, including facilitating cancer cell stemness and the activation of cancer-associated fibroblasts. Moreover, GREM1 has been described to bind and signal to vascular endothelial growth factor receptor (VEGFR) and stimulate angiogenesis, as well as epidermal and fibroblast growth factor receptor (EGFR and FGFR) to elicit tumor-promoting effects in breast and prostate cancer, respectively. In contrast, a 2022 report revealed that GREM1 can promote an epithelial state in pancreatic cancers, thereby inhibiting pancreatic tumor growth and metastasis. In this commentary, we will review these disparate findings and attempt to provide clarity around the role of GREM1 signaling in cancer.

Nanomedicine Strategies for Targeting Tumor Stroma

The tumor stroma, or the microenvironment surrounding solid tumors, can significantly impact the effectiveness of cancer therapies. The tumor microenvironment is characterized by high interstitial pressure, a consequence of leaky vasculature, and dense stroma created by excessive deposition of various macromolecules such as collagen, fibronectin, and hyaluronic acid (HA). In addition, non-cancerous cells such as cancer-associated fibroblasts (CAFs) and the extracellular matrix (ECM) itself can promote tumor growth. In recent years, there has been increased interest in combining standard cancer treatments with stromal-targeting strategies or stromal modulators to improve therapeutic outcomes. Furthermore, the use of nanomedicine, which can improve the delivery and retention of drugs in the tumor, has been proposed to target the stroma. This review focuses on how different stromal components contribute to tumor progression and impede chemotherapeutic delivery. Additionally, this review highlights recent advancements in nanomedicine-based stromal modulation and discusses potential future directions for developing more effective stroma-targeted cancer therapies.

Photodynamic Stromal Depletion in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid malignancies, with a five-year survival of less than 10%. The resistance of the disease and the associated lack of therapeutic response is attributed primarily to its dense, fibrotic stroma, which acts as a barrier to drug perfusion and permits tumour survival and invasion. As clinical trials of chemotherapy (CT), radiotherapy (RT), and targeted agents have not been successful, improving the survival rate in unresectable PDAC remains an urgent clinical need. Photodynamic stromal depletion (PSD) is a recent approach that uses visible or near-infrared light to destroy the desmoplastic tissue. Preclinical evidence suggests this can resensitise tumour cells to subsequent therapies whilst averting the tumorigenic effects of tumour-stromal cell interactions. So far, the pre-clinical studies have suggested that PDT can successfully mediate the destruction of various stromal elements without increasing the aggressiveness of the tumour. However, the complexity of this interplay, including the combined tumour promoting and suppressing effects, poses unknowns for the clinical application of photodynamic stromal depletion in PDAC.

The role of epithelial-mesenchymal transition and autophagy in pancreatic ductal adenocarcinoma invasion

Of all pancreatic cancer (PC) cases, approximately 90% are pancreatic ductal adenocarcinoma (PDAC), which progress rapidly due to its high degree of invasiveness and high metastatic potential. Epithelial-mesenchymal transition (EMT) is a prerequisite for cancer cell invasion and spread, and it is mediated by the specific cellular behaviors and the tumor microenvironment. Autophagy has long been a target of cancer therapy, and it has been considered to play a dual and contradictory role, particularly regarding EMT-mediated PDAC invasion. This review discusses the characteristics and the biological role of EMT and autophagy from a cellular perspective, explaining invasion as a survival behavior of PDAC, with the aim of providing novel insights into targeting EMT and autophagy to overcome PDAC invasion.

Systemic Alterations in Type-2 Conventional Dendritic Cells Lead to Impaired Tumor Immunity in Pancreatic Cancer

Intratumoral T-cell dysfunction is a hallmark of pancreatic tumors, and efforts to improve dendritic cell (DC)-mediated T-cell activation may be critical in treating these immune therapy unresponsive tumors. Recent evidence indicates that mechanisms that induce dysfunction of type 1 conventional DCs (cDC1) in pancreatic adenocarcinomas (PDAC) are drivers of the lack of responsiveness to checkpoint immunotherapy. However, the impact of PDAC on systemic type 2 cDC2 development and function has not been well studied. Herein, we report the analysis of 3 cohorts, totaling 106 samples, of human blood and bone marrow (BM) from patients with PDAC for changes in cDCs. We found that circulating cDC2s and their progenitors were significantly decreased in the blood of patients with PDAC, and repressed numbers of cDC2s were associated with poor prognosis. Serum cytokine analyses identified IL6 as significantly elevated in patients with PDAC and negatively correlated with cDC numbers. In vitro, IL6 impaired the differentiation of cDC1s and cDC2s from BM progenitors. Single-cell RNA sequencing analysis of human cDC progenitors in the BM and blood of patients with PDAC showed an upregulation of the IL6/STAT3 pathway and a corresponding impairment of antigen processing and presentation. These results suggested that cDC2s were systemically suppressed by inflammatory cytokines, which was linked to impaired antitumor immunity.

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.

FGF19-Induced Inflammatory CAF Promoted Neutrophil Extracellular Trap Formation in the Liver Metastasis of Colorectal Cancer

Liver metastasis is the main cause of death in patients with colorectal cancer (CRC); thus, necessitating effective biomarkers and therapeutic targets for colorectal cancer liver metastasis (CRLM). Fibroblast growth factor 19 (FGF19) is a protumorigenic gene in numerous human malignancies. In this study, it is shown that FGF19 plays an indispensable role in CRLM. FGF19 expression and secretion are markedly correlated with liver metastasis and lower overall survival rates of patients with CRC. An in vivo metastasis model shows that FGF19 overexpression confers stronger liver-metastatic potential in CRC cells. Mechanistically, FGF19 exerts an immunomodulatory function that creates an environment conducive for metastasis in CRLM. FGF19 mediates the polarization of hepatic stellate cells to inflammatory cancer-associated fibroblasts (iCAFs) by activating the autocrine effect of IL-1α via the FGFR4-JAK2-STAT3 pathway. FGF19-induced iCAFs promote neutrophil infiltration and mediate neutrophil extracellular trap (NET) formation in liver metastatic niches via the production of complement C5a and IL-1β, which in turn accelerates the liver colonization of CRC cells. Importantly, targeting FGF19 signaling with fisogatinib efficiently suppresses FGF19-induced liver metastasis in a mouse model. In summary, this study describes the mechanism by which FGF19 regulates CRLM, thereby providing a novel target for CRLM intervention.

An agarose-alginate microfluidic device for the study of spheroid invasion, ATRA inhibits CAFs-mediated matrix remodeling

Growing evidence demonstrates that cancer-associated fibroblasts (CAF) are responsible for tumor genesis, growth, metastasis, and treatment response. Therefore, targeting these cells may contribute to tumor control. It has been proposed that targeting key molecules and pathways of proliferative functions can be more effective than killing CAFs. In this regard, multicellular aggregates, like spheroids, can be used as human tumor models. Spheroids closely resemble human tumors and mimic many of their features. Microfluidic systems are ideal for cultivation and study of spheroids. These systems can be designed with different biological and synthetic matrices in order to have a more realistic simulation of the tumor microenvironment (TME). In this study, we investigated the effect of all-trans retinoic acid (ATRA) on 3D spheroid invasion of MDA-MB cells exposed to hydrogel matrix derived from CAFs. The number of invasive cells significantly decreased in CAF-ECM hydrogel treated with ATRA (p < 0.05), which indicates that ATRA could be effective for CAFs normalization. This experiment was done using an agarose-alginate microfluidic chip. As compared with common methods, such hydrogel casting is an easier method for chip fabrication and can even reduce costs.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10616-023-00578-y.

Skin fibroblast functional heterogeneity in health and disease

Fibroblasts are the major cell population of connective tissue, including the skin dermis, and are best known for their function in depositing and remodelling the extracellular matrix. Besides their role in extracellular matrix homeostasis, fibroblasts have emerged as key players in many biological processes ranging from tissue immunity and wound healing to hair follicle development. Recent advances in single-cell RNA-sequencing technologies have revealed an astonishing transcriptional fibroblast heterogeneity in the skin and other organs. A key challenge in the field is to understand the functional relevance and significance of the identified new cell clusters in health and disease. Here, we discuss the functionally distinct fibroblast subtypes identified in skin homeostasis and repair and how they evolve in fibrotic disease conditions, in particular keloid scars and cancer. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Forces exerted and transduced by cancer-associated fibroblasts during cancer progression

Although it is well-known that cancer-associated fibroblasts (CAFs) play a key role in regulating tumor progression, the effects of mechanical tissue changes on CAFs are understudied. Myofibroblastic CAFs (myCAFs), in particular, are known to alter tumor matrix architecture and composition, heavily influencing the mechanical forces in the tumor microenvironment (TME), but much less is known about how these mechanical changes initiate and maintain the myCAF phenotype. Additionally, recent studies have pointed to the existence of CAFs in circulating tumor cell clusters, indicating that CAFs may be subject to mechanical forces beyond the primary TME. Due to their pivotal role in cancer progression, targeting CAF mechanical regulation may provide therapeutic benefit. Here, we will discuss current knowledge and summarize existing gaps in how CAFs regulate and are regulated by matrix mechanics, including through stiffness, solid and fluid stresses, and fluid shear stress.

The clinical terrain of immunotherapies in heterogeneous pancreatic cancer: unravelling challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is the most common and aggressive type of pancreatic cancer and has abysmal survival rates. In the past two decades, immunotherapeutic agents with success in other cancer types have gradually been trialled against PDACs at different stages of cancer progression, either as a monotherapy or in combination with chemotherapy. Unfortunately, to this day, chemotherapy still prolongs the survival rates the most and is prescribed in clinics despite the severe side effects in other cancer types. The low success rates of immunotherapy against PDAC have been attributed most frequently to its complex and multi-faceted tumour microenvironment (TME) and low mutational burden. In this review, we give a comprehensive overview of the immunotherapies tested in PDAC clinical trials thus far, their limitations, and potential explanations for their failure. We also discuss the existing classification of heterogenous PDACs into cancer, cancer-associated fibroblast, and immune subtypes and their potential opportunity in patient selection as a form of personalisation of PDAC immunotherapy. © 2023 The Pathological Society of Great Britain and Ireland.

Schwann cells regulate tumor cells and cancer-associated fibroblasts in the pancreatic ductal adenocarcinoma microenvironment

Neuropathy is a feature more frequently observed in pancreatic ductal adenocarcinoma (PDAC) than other tumors. Schwann cells, the most prevalent cell type in peripheral nerves, migrate toward tumor cells and associate with poor prognosis in PDAC. To unveil the effects of Schwann cells on the neuro-stroma niche, here we perform single-cell RNA-sequencing and microarray-based spatial transcriptome analysis of PDAC tissues. Results suggest that Schwann cells may drive tumor cells and cancer-associated fibroblasts (CAFs) to more malignant subtypes: basal-like and inflammatory CAFs (iCAFs), respectively. Moreover, in vitro and in vivo assays demonstrate that Schwann cells enhance the proliferation and migration of PDAC cells via Midkine signaling and promote the switch of CAFs to iCAFs via interleukin-1α. Culture of tumor cells and CAFs with Schwann cells conditioned medium accelerates PDAC progression. Thus, we reveal that Schwann cells induce malignant subtypes of tumor cells and CAFs in the PDAC milieu.

Organoids: opportunities and challenges of cancer therapy

Organoids are a class of multicellular structures with the capability of self-organizing and the characteristic of original tissues, they are generated from stem cells in 3D culture in vitro. Organoids can mimic the occurrence and progression of original tissues and widely used in disease models in recent years. The ability of tumor organoids to retain characteristic of original tumors make them unique for tumorigenesis and cancer therapy. However, the history of organoid development and the application of organoid technology in cancer therapy are not well understood. In this paper, we reviewed the history of organoids development, the culture methods of tumor organoids establishing and the applications of organoids in cancer research for better understanding the process of tumor development and providing better strategies for cancer therapy. The standardization of organoids cultivation facilitated the large-scale production of tumor organoids. Moreover, it was found that combination of tumor organoids and other cells such as immune cells, fibroblasts and nervous cells would better mimic the microenvironment of tumor progression. This might be important developing directions for tumor organoids in the future.

Medical Biology of Cancer-Associated Fibroblasts in Pancreatic Cancer

Pancreatic cancer is one of the deadliest forms of cancer with one of the lowest 5-year survival rates of all cancer types. A defining characteristic of pancreatic cancer is the existence of dense desmoplastic stroma that, when exposed to stimuli such as cytokines, growth factors, and chemokines, generate a tumor-promoting environment. Cancer-associated fibroblasts (CAFs) are activated during the progression of pancreatic cancer and are a crucial component of the tumor microenvironment (TME). CAFs are primarily pro-tumorigenic in their activated state and function as promoters of cancer invasion, proliferation, metastasis, and immune modulation. Aided by many signaling pathways, cytokines, and chemokines in the tumor microenvironment, CAFs can originate from many cell types including resident fibroblasts, mesenchymal stem cells, pancreatic stellate cells, adipocytes, epithelial cells, endothelial cells, and other cell types. CAFs are a highly heterogeneous cell type expressing a variety of surface markers and performing a wide range of tumor promoting and inhibiting functions. Single-cell transcriptomic analyses have revealed a high degree of specialization among CAFs. Some examples of CAF subpopulations include myofibrotic CAFs (myCAFs), which exhibit a matrix-producing contractile phenotype; inflammatory CAFs (iCAF) that are classified by their immunomodulating, secretory phenotype; and antigen-presenting CAFs (apCAFs), which have antigen-presenting capabilities and express Major Histocompatibility Complex II (MHC II). Over the last several years, various attempts have been undertaken to describe the mechanisms of CAF-tumor cell interaction, as well as CAF-immune cell interaction, that contribute to tumor proliferation, invasion, and metastasis. Although our understanding of CAF biology in cancer has steadily increased, the extent of CAFs heterogeneity and their role in the pathobiology of pancreatic cancer remains elusive. In this regard, it becomes increasingly evident that further research on CAFs in pancreatic cancer is necessary.

Cancer-associated fibroblast classification in single-cell and spatial proteomics data

Cancer-associated fibroblasts (CAFs) are a diverse cell population within the tumour microenvironment, where they have critical effects on tumour evolution and patient prognosis. To define CAF phenotypes, we analyse a single-cell RNA sequencing (scRNA-seq) dataset of over 16,000 stromal cells from tumours of 14 breast cancer patients, based on which we define and functionally annotate nine CAF phenotypes and one class of pericytes. We validate this classification system in four additional cancer types and use highly multiplexed imaging mass cytometry on matched breast cancer samples to confirm our defined CAF phenotypes at the protein level and to analyse their spatial distribution within tumours. This general CAF classification scheme will allow comparison of CAF phenotypes across studies, facilitate analysis of their functional roles, and potentially guide development of new treatment strategies in the future.

High CD142 Level Marks Tumor-Promoting Fibroblasts with Targeting Potential in Colorectal Cancer

Colorectal cancer (CRC) has a high incidence and is one of the leading causes of cancer-related death. The accumulation of cancer-associated fibroblasts (CAF) induces an aggressive, stem-like phenotype in tumor cells, and it indicates a poor prognosis. However, cellular heterogeneity among CAFs and the targeting of both stromal and CRC cells are not yet well resolved. Here, we identified CD142high fibroblasts with a higher stimulating effect on CRC cell proliferation via secreting more hepatocyte growth factor (HGF) compared to CD142low CAFs. We also found that combinations of inhibitors that had either a promising effect in other cancer types or are more active in CRC compared to normal colonic epithelium acted synergistically in CRC cells. Importantly, heat shock protein 90 (HSP90) inhibitor selected against CD142high fibroblasts, and both CRC cells and CAFs were sensitive to a BCL-xL inhibitor. However, targeting mitogen-activated protein kinase kinase (MEK) was ineffective in fibroblasts, and an epigenetic inhibitor selected for a tumor cell population with markers of aggressive behavior. Thus, we suggest BCL-xL and HSP90 inhibitors to eliminate cancer cells and decrease the tumor-promoting CD142high CAF population. This may be the basis of a strategy to target both CRC cells and stromal fibroblasts, resulting in the inhibition of tumor relapse.

IL1R1+ cancer-associated fibroblasts drive tumor development and immunosuppression in colorectal cancer

Fibroblasts have a considerable functional and molecular heterogeneity and can play various roles in the tumor microenvironment. Here we identify a pro-tumorigenic IL1R1⁺, IL-1-high-signaling subtype of fibroblasts, using multiple colorectal cancer (CRC) patient single cell sequencing datasets. This subtype of fibroblasts is linked to T cell and macrophage suppression and leads to increased cancer cell growth in 3D co-culture assays. Furthermore, both a fibroblast-specific IL1R1 knockout and IL-1 receptor antagonist Anakinra administration reduce tumor growth in vivo. This is accompanied by reduced intratumoral Th17 cell infiltration. Accordingly, CRC patients who present with IL1R1-expressing cancer-associated-fibroblasts (CAFs), also display elevated levels of immune exhaustion markers, as well as an increased Th17 score and an overall worse survival. Altogether, this study underlines the therapeutic value of targeting IL1R1-expressing CAFs in the context of CRC.

The Origin, Differentiation, and Functions of Cancer-Associated Fibroblasts in Gastrointestinal Cancer

Emerging evidence has shown the importance of the tumor microenvironment in tumorigenesis and progression. Cancer-associated fibroblasts (CAFs) are one of the most infiltrated stroma cells of the tumor microenvironment in gastrointestinal tumors. CAFs play crucial roles in tumor development and therapeutic response by biologically secreting soluble factors or structurally remodeling the extracellular matrix. Conceivably, CAFs may become excellent targets for tumor prevention and treatment. However, the limited knowledge of the heterogeneity of CAFs represents a huge challenge for clinically targeting CAFs. In this review, we summarize the newest understanding of gastrointestinal CAFs, with a special focus on their origin, differentiation, and function. We also discuss the current understanding of CAF subpopulations as shown by single-cell technologies.

Splicing Factor SRSF1 Promotes Pancreatitis and KRASG12D-Mediated Pancreatic Cancer

Inflammation is strongly associated with pancreatic ductal adenocarcinoma (PDAC), a highly lethal malignancy. Dysregulated RNA splicing factors have been widely reported in tumorigenesis, but their involvement in pancreatitis and PDAC is not well understood. Here, we report that the splicing factor SRSF1 is highly expressed in pancreatitis, PDAC precursor lesions, and tumors. Increased SRSF1 is sufficient to induce pancreatitis and accelerate KRASG12D-mediated PDAC. Mechanistically, SRSF1 activates MAPK signaling-partly by upregulating interleukin 1 receptor type 1 (IL1R1) through alternative-splicing-regulated mRNA stability. Additionally, SRSF1 protein is destabilized through a negative feedback mechanism in phenotypically normal epithelial cells expressing KRASG12D in mouse pancreas and in pancreas organoids acutely expressing KRASG12D, buffering MAPK signaling and maintaining pancreas cell homeostasis. This negative feedback regulation of SRSF1 is overcome by hyperactive MYC, facilitating PDAC tumorigenesis. Our findings implicate SRSF1 in the etiology of pancreatitis and PDAC, and point to SRSF1-misregulated alternative splicing as a potential therapeutic target.

SIGNIFICANCE

We describe the regulation of splicing factor SRSF1 expression in the context of pancreas cell identity, plasticity, and inflammation. SRSF1 protein downregulation is involved in a negative feedback cellular response to KRASG12D expression, contributing to pancreas cell homeostasis. Conversely, upregulated SRSF1 promotes pancreatitis and accelerates KRASG12D-mediated tumorigenesis through enhanced IL1 and MAPK signaling. This article is highlighted in the In This Issue feature, p. 1501.