Isolation of normal and cancer-associated fibroblasts from fresh tissues by Fluorescence Activated Cell Sorting (FACS)

Assessment and process optimization of high throughput biofabrication of immunocompetent breast cancer model for drug screening applications

Recent advancements in 3D cancer modeling have significantly enhanced our ability to delve into the intricacies of carcinogenesis. Despite the pharmaceutical industry's substantial investment of both capital and time in the drug screening and development pipeline, a concerning trend persists: drug candidates screened on conventional cancer models exhibit a dismal success rate in clinical trials. One pivotal factor contributing to this discrepancy is the absence of drug testing on pathophysiologically biomimetic 3D cancer models during pre-clinical stages. Unfortunately, current manual methods of 3D cancer modeling, such as spheroids and organoids, suffer from limitations in reproducibility and scalability. In our study, we have meticulously developed 3D bioprinted breast cancer model utilizing decellularized adipose tissue-based hydrogel obtained via a detergent-free decellularization method. Our innovative printing techniques allows for rapid, high-throughput fabrication of 3D cancer models in a 96-well plate format, demonstrating unmatched scalability and reproducibility. Moreover, we have conducted extensive validation, showcasing the efficacy of our platform through drug screening assays involving two potent anti-cancer drugs, 5-Fluorouracil and PRIMA-1Met. Notably, our platform facilitates effortless imaging and gene expression analysis, streamlining the evaluation process. In a bid to enhance the relevance of our cancer model, we have introduced a heterogeneous cell population into the DAT-based bioink. Through meticulous optimization and characterization, we have successfully developed a biomimetic immunocompetent breast cancer model, complete with microenvironmental cues and diverse cell populations. This breakthrough paves the way for rapid multiplex drug screening and the development of personalized cancer models, marking a paradigm shift in cancer research and pharmaceutical development.

Cancer-associated fibroblasts promote enzalutamide resistance and PD-L1 expression in prostate cancer through CCL5-CCR5 paracrine axis

Cancer-associated fibroblasts (CAFs) have been shown to play a key role in prostate cancer treatment resistance, but the role of CAFs in the initial course of enzalutamide therapy for prostate cancer remains unclear. Our research revealed that CAFs secrete CCL5, which promotes the upregulation of androgen receptor (AR) expression in prostate cancer cells, leading to resistance to enzalutamide therapy. Furthermore, CCL5 also enhances the expression of tumor programmed death-ligand 1 (PD-L1), resulting in immune escape. Mechanistically, CCL5 binds to the receptor CCR5 on prostate cancer cells and activates the AKT signaling pathway, leading to the upregulation of AR and PD-L1. The CCR5 antagonist maraviroc to inhibit the CAFs mediated CCL5 signaling pathway can effectively reduce the expression of AR and PD-L1, and improve the efficacy of enzalutamide. This study highlights a promising therapeutic approach targeting the CCL5-CCR5 signaling pathway to improve the effectiveness of enzalutamide.

Single-cell disulfidptosis regulator patterns guide intercellular communication of tumor microenvironment that contribute to kidney renal clear cell carcinoma progression and immunotherapy

Background

Disulfidptosis, an emerging type of programmed cell death, plays a pivotal role in various cancer types, notably impacting the progression of kidney renal clear cell carcinoma (KIRC) through the tumor microenvironment (TME). However, the specific involvement of disulfidptosis within the TME remains elusive.

Methods

Analyzing 41,784 single cells obtained from seven samples of KIRC through single-cell RNA sequencing (scRNA-seq), this study employed nonnegative matrix factorization (NMF) to assess 24 disulfidptosis regulators. Pseudotime analysis, intercellular communication mapping, determination of transcription factor activities (TFs), and metabolic profiling of the TME subgroup in KIRC were conducted using Monocle, CellChat, SCENIC, and scMetabolism. Additionally, public cohorts were utilized to predict prognosis and immune responses within the TME subgroup of KIRC.

Results

Through NMF clustering and differential expression marker genes, fibroblasts, macrophages, monocytes, T cells, and B cells were categorized into four to six distinct subgroups. Furthermore, this investigation revealed the correlation between disulfidptosis regulatory factors and the biological traits, as well as the pseudotime trajectories of TME subgroups. Notably, disulfidptosis-mediated TME subgroups (DSTN+CD4T-C1 and FLNA+CD4T-C2) demonstrated significant prognostic value and immune responses in patients with KIRC. Multiple immunohistochemistry (mIHC) assays identified marker expression within both cell clusters. Moreover, CellChat analysis unveiled diverse and extensive interactions between disulfidptosis-mediated TME subgroups and tumor epithelial cells, highlighting the TNFSF12-TNFRSF12A ligand-receptor pair as mediators between DSTN+CD4T-C1, FLNA+CD4T-C2, and epithelial cells.

Conclusion

Our study sheds light on the role of disulfidptosis-mediated intercellular communication in regulating the biological characteristics of the TME. These findings offer valuable insights for patients with KIRC, potentially guiding personalized immunotherapy approaches.

Rocuronium bromide suppresses esophageal cancer via blocking the secretion of C-X-C motif chemokine ligand 12 from cancer associated fibroblasts

BACKGROUND

Cancer associated fibroblasts (CAFs) communicate metabolically with tumor genesis and development. Rocuronium bromide (RB) is reported to exert certain inhibitory effect on tumor. Here, we investigate the role of RB in esophageal cancer (EC) malignant progression.

METHODS

Tumor xenograft models with EC cells were locally and systemically administrated with RB to detect the influence of different administrations on tumor progression. Mouse CAFs PDGFRα⁺/F4/80^- were sorted by Flow cytometry with specific antibodies. CAFs were treated with RB and co-cultured with EC cells. The proliferation, invasion and apoptosis assays of EC cells were performed to detect the influences of RB targeting CAFs on EC cell malignant progression. Human fibroblasts were employed to perform these detections to confirm RB indirect effect on EC cells. The gene expression changes of CAFs response to RB treatment were detected using RNA sequencing and verified by Western blot, immunohistochemistry and ELISA.

RESULTS

Tumors in xenograft mice were observed significantly inhibited by local RB administration, but not by systemic administration. Moreover EC cells did not show obvious change in viability when direct stimulated with RB in vitro. However, when CAFs treated with RB were co-cultured with EC cells, obvious suppressions were observed in EC cell malignancy, including proliferation, invasion and apoptosis. Human fibroblasts were employed to perform these assays and similar results were obtained. RNA sequencing data of human fibroblast treated with RB, and Western blot, immunohistochemistry and ELISA results all showed that CXCL12 expression was significantly diminished in vivo and in vitro by RB. EC cells direct treated with CXCL12 showed much higher malignancy. Moreover cell autophagy and PI3K/AKT/mTOR signaling pathway in CAFs were both suppressed by RB which can be reversed by Rapamycin pretreatment.

CONCLUSIONS

Our data suggest that RB could repress PI3K/AKT/mTOR signaling pathway and autophagy to block the CXCL12 expression in CAFs, thereby weakening the CXCL12-mediated EC tumor progression. Our data provide a novel insight into the underlying mechanism of RB inhibiting EC, and emphasize the importance of tumor microenvironment (cytokines from CAFs) in modulating cancer malignant progression.

Cancer-associated fibroblasts-derived exosomes from chemoresistant patients regulate cisplatin resistance and angiogenesis by delivering VEGFA in colorectal cancer

The purpose of this study was to investigate the effect of chemoresistant cancer-associated fibroblasts (R-CAFs) against cisplatin (DDP) on colorectal cancer (CRC) progression. First, clinical tissue samples of chemoresistant or chemosensitive CRC patients were collected to isolate R-CAFs or chemosensitive CAFs (S-CAFs), respectively. HT29 cells or HUVECs were co-cultured with R-CAFs by transwell device. Then the proliferation and apoptosis of HT29 cells were detected with Cell Counting Kit-8 (CCK-8) and flow cytometry. Transwell assay and tube formation assay was used to detect the migration and angiogenesis of HUVECs. In addition, a colorectal cancer transplantation model was established subcutaneously in nude mice by injecting stably transfected HT29 cells and exosomes from different CAF groups, and then the tumor volume and weight were measured and recorded. Hematoxylin and eosin staining, immunohistochemistry, and terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) staining were performed to characterize the histopathological characteristics and apoptosis level of tumor tissues, respectively. S-CAFs and R-CAFs were isolated successfully. HT29 cell co-culture with R-CAFs significantly affected the proliferation and apoptosis of HT29 cells. Exosomes derived from R-CAFs (R-CAFs-Exo) were delivered to HT29 cells, which could induce viability, suppress apoptosis and accelerate the angiogenesis of CRC. In addition, VEGFA was highly expressed in R-CAFs-Exo, which might indicate that R-CAFs could transmit VEGFA through exosomes. Overexpressed VEGFA in R-CAFs apparently regulates the viability, apoptosis, DDP resistance, and angiogenesis of CRC. In-vivo experiments confirmed that R-CAFs-Exo promoted the progression of CRC and DDP resistance by delivering VEGFA . R-CAFs-derived exosomes promote the viability, apoptosis, DDP resistance, and angiogenesis of CRC by delivering VEGFA .

Fibroblast Isolation from Mammary Gland Tissue and Syngeneic Murine Breast Cancer Models

Cancer-associated fibroblasts (CAFs) are vital within the tumor ecosystem, regulating tumor growth, dissemination, and response to therapy through crosstalk with tumor cells, infiltrating immune and vascular cells, as well as components of the extracellular matrix (ECM). CAFs have thus emerged as potential therapeutic targets to complement cancer cell-targeted therapies. To study CAF-tumor cell crosstalk ex vivo, robust isolation methods of primary CAFs are required. Here, we present protocols to isolate, expand, and culture two types of fibroblasts: (1) healthy murine mammary gland fibroblasts, a key source of the CAF population in breast tumor models and (2) CAFs derived from syngeneic murine breast tumors. Isolated mammary fibroblasts and CAFs are suitable for use in a variety of downstream cellular and molecular experiments. We expect these methods to be useful to scientists studying the properties of fibroblasts and CAFs and the interaction between CAFs and the various components of the tumor microenvironment (TME).

Pan-cancer analysis identifies NT5E as a novel prognostic biomarker on cancer-associated fibroblasts associated with unique tumor microenvironment

Background: Ecto-5'-nucleotidase (NT5E) encodes the cluster of differentiation 73 (CD73), whose overexpression contributes to the formation of immunosuppressive tumor microenvironment and is related to exacerbated prognosis, increased risk of metastasis and resistance to immunotherapy of various tumors. However, the prognostic significance of NT5E in pan-cancer is obscure so far. Methods: We explored the expression level of NT5E in cancers and adjacent tissues and revealed the relationship between the NT5E expression level and clinical outcomes in pan-cancer by utilizing the UCSC Xena database. Then, correlation analyses were performed to evaluate the relationship between NT5E expression and immune infiltration level via EPIC, MCP-counter and CIBERSORT methods, and the enrichment analysis were employed to identify NT5E-interacting molecules and functional pathways. Furthermore, we conducted single-cell analysis to explore the potential role of NT5E on single-cell level based on the CancerSEA database. Meanwhile, gene set enrichment analysis (GSEA) in single-cell level was also conducted in TISCH database and single-cell signature explorer was utilized to evaluate the epithelial-mesenchymal transition (EMT) level in each cell type. Results: The expression level of NT5E was aberrant in almost all cancer types, and was correlated with worse prognosis in several cancers. Notably, NT5E overexpression was related to worse overall survival (OS) in pancreatic adenocarcinoma (PAAD), head and neck squamous cell carcinoma (HNSC), mesothelioma (MESO), stomach adenocarcinoma (STAD), uveal melanoma (UVM) and cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) (p < 0.01). NT5E-related immune microenvironment analysis revealed that NT5E is associated positively with the degree of infiltration of cancer-associated fibroblasts (CAFs) and endothelial cells in most cancers. Enrichment analysis of cellular component (CC) demonstrated the critical part of NT5E played in cell-substrate junction, cell-substrate adherens junction, focal adhesion and external side of plasma membrane. Finally, single-cell analysis of NT5E illuminated that EMT function of CAFs was elevated in basal cell carcinoma (BCC), skin cutaneous melanoma (SKCM), HNSC and PAAD. Conclusion: NT5E could serve as a potential prognostic biomarker for cancers. The potential mechanism may be related to the upregulated EMT function of CAFs, which provides novel inspiration for immunotherapy by targeting CAFs with high NT5E expression.

The Combination of Zerumbone with 5-Fluorouracil for Sensitizing Colorectal Cancer-Associated Fibroblasts to Treatment

The present study aimed to evaluate the synergic effects of combination therapy on 5-fluorouracil (5-FU) resistance-cancer-associated fibroblasts (CAFs) to treatment. Chemotherapy resistance is an important challenge in colorectal cancer (CRC) eradication attention to the tumor microenvironment (TME) is very important. CAFs in the TME play an essential role in cancer chemoresistance and relapse. Additionally, many patients with advanced CRC show resistance to 5-FU therapy. Anti-tumorigenic activities of ZER, a chemopreventive compound derived from the rhizomes of the wild ginger, have been demonstrated. Synergistic and potentiating effects of combination therapy, using herbal and chemical drugs, can improve patients’ response. At the first, CAFs were isolated from a CRC patient and sorted by fluorescent-activated cell sorting (FACS), then, confirmed by flow cytometry, and immunocytochemistry (ICC). The effect of 5-FU and ZER on the cell viability was investigated by MTT assay in a dose and time-dependent manner, after that, the expression of vimentin, β-catenin, and survivin was quantified. Apoptosis, cell cycle, and invasion were analyzed by flow cytometry and scratch test, respectively. ZER could significantly sensitize CAFs cells to 5-FU. A combination of 5-FU + ZER revealed a marked decrease in the marker of interest in both mRNA and protein levels compared to control groups, including 5-FU, ZER treated, and untreated cells. Functional evaluation of cells in different groups presented significant suppression in migration of CAFs and an apparent increase in cell arrest and apoptosis by 5-FU + ZER treatment.

Cancer-associated fibroblasts and their role in tumor progression

The stromal elements of a malignant tumor can promote cancer progression and metastasis. The structure of the tumor stroma includes connective tissue elements, blood vessels, nerves, and extracellular matrix (ECM). Some of the cellular elements of the tumor stroma are cancer-associated fibroblasts (CAFs). The origin and function of CAFs have been actively studied over the past thirty years. CAFs produce collagen, the main scaffold protein of the extracellular matrix. Collagen in the tumor stroma stimulates fibrosis, enhances the rigidity of tumor tissue, and disrupts the transmission of proliferation and differentiation signaling pathways. CAFs control tumor angiogenesis, cell motility, tumor immunogenic properties, and the development of resistance to chemo- and immunotherapy. As a result of metabolic adaptation of rapidly growing tumor tissue to the nutrients and oxygen deprivation, the main type of energy production in cells changes from oxidative phosphorylation to anaerobic glycolysis. These changes lead to sequential molecular alterations, including the induction of specified transcriptional factors that result in the CAFs activation. The molecular phenotype of activated CAFs is similar to fibroblasts activated during inflammation. In activated CAFs, alpha-smooth muscle actin (α-SMA) is synthetized de novo and various proteases and fibronectin are produced. Since CAFs are found in all types of carcinomas, these cells are potential targets for the development of new approaches for anticancer therapy. Some CAFs originate from resident fibroblasts of the organs invaded by the tumor, while others originate from epithelial tumor cells, which are undergoing an epithelial-mesenchymal transition (EMT). To date, many molecular and metabolic inducers of the EMT have been discovered including the transforming growth factor-beta (TGF-β), hypoxia, and inflammation. This review classifies modern concepts of molecular markers of CAFs, their functional features, and discusses the stages of epithelial-mesenchymal transition, and the potential of CAFs as a target for antitumor therapy.

Isolation of Normal and Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAFs) play important roles in regulating tumor progression, metastasis, and response to therapies. Accurately modeling the interplay between cancer cells and the tumor microenvironment (TME) requires the use of primary cells from patient samples. Here we describe methods for the isolation of both primary CAFs and fibroblasts from omental tissue using a combination of mechanical dissociation and enzymatic digestion. Primary cells can be used for functional and mechanistic studies and may be safely cryopreserved.

PDGF-BB regulates the transformation of fibroblasts into cancer-associated fibroblasts via the lncRNA LURAP1L-AS1/LURAP1L/IKK/IκB/NF-κB signaling pathway

The most abundant cells in the tumor microenvironment are cancer-associated fibroblasts (CAFs). They play an important role in oral squamous cell carcinoma (OSCC) angiogenesis, invasion and metastasis. Platelet-derived growth factor (PDGF)-BB has an obvious regulating effect on the formation of CAFs through binding to PDGF receptor (PDGFR)-β, but the role of long non-coding (lnc)RNA in PDGF-BB-induced transformation of fibroblasts into CAFs remains poorly understood. Using an lncRNA ChIP, 370 lncRNA transcripts were identified to be significantly and differentially expressed between fibroblasts and PDGF-BB-induced fibroblasts, including 240 upregulated lncRNAs and 130 downregulated lncRNAs, indicating that lncRNAs are involved in the regulation of the transformation of CAFs. Previous studies have shown that the nuclear factor (NF)-κB signaling pathway plays an important role in the activation of CAFs. Dual-luciferase reporter assay and co-immunoprecipitation were conducted to confirm that the leucine-rich adaptor protein 1-like (LURAP1L), which is the target of lncRNA LURAP1L antisense RNA 1 (LURAP1L-AS1) had a positive regulatory effect on I-κB kinase (IKK)/NF-κB signaling. Therefore, LURAP1L-AS1 was selected and PDGF-BB was demonstrated to upregulate the expression of LURAP1L-AS1 and LURAP1L, which was reversed by a PDGFR-β inhibitor. Subsequently, knocking down LURAP1L-AS1 suppressed the expression of PDGF-BB-induced fibroblast activation marker protein α-smooth muscle actin, fibroblast activation protein-α, PDGFR-β and phosphorylated (p)-PDGFR-β. IKKα, p-IĸB and p-NF-κB were downregulated by the knockdown of LURAP1L-AS1 and upregulated by overexpression of LURAP1L-AS1. The present study indicates that LURAP1L-AS1/LURAP1L/IKK/IĸB/NF-κB plays an important regulatory role in PDGF-BB-induced fibroblast activation and may become a potential target for the treatment of OSCC.

Evolution of fibroblasts in the lung metastatic microenvironment is driven by stage-specific transcriptional plasticity

Mortality from breast cancer is almost exclusively a result of tumor metastasis, and lungs are one of the main metastatic sites. Cancer-associated fibroblasts are prominent players in the microenvironment of breast cancer. However, their role in the metastatic niche is largely unknown. In this study, we profiled the transcriptional co-evolution of lung fibroblasts isolated from transgenic mice at defined stage-specific time points of metastases formation. Employing multiple knowledge-based platforms of data analysis provided powerful insights on functional and temporal regulation of the transcriptome of fibroblasts. We demonstrate that fibroblasts in lung metastases are transcriptionally dynamic and plastic, and reveal stage-specific gene signatures that imply functional tasks, including extracellular matrix remodeling, stress response, and shaping the inflammatory microenvironment. Furthermore, we identified Myc as a central regulator of fibroblast rewiring and found that stromal upregulation of Myc transcriptional networks is associated with disease progression in human breast cancer.

Deciphering the temporal heterogeneity of cancer-associated fibroblast subpopulations in breast cancer

BACKGROUND

Cancer-associated fibroblasts (CAFs) comprise a heterogeneous population of stromal cells within the tumour microenvironment. CAFs exhibit both tumour-promoting and tumour-suppressing functions, making them exciting targets for improving cancer treatments. Careful isolation, identification, and characterisation of CAF heterogeneity is thus necessary for ex vivo validation and future implementation of CAF-targeted strategies in cancer.

METHODS

Murine 4T1 (metastatic) and 4T07 (poorly/non-metastatic) orthotopic triple negative breast cancer tumours were collected after 7, 14, or 21 days. The tumours were analysed via flow cytometry for the simultaneous expression of six CAF markers: alpha smooth muscle actin (αSMA), fibroblast activation protein alpha (FAPα), platelet derived growth factor receptor alpha and beta (PDGFRα and PDGFRβ), CD26/DPP4 and podoplanin (PDPN). All non-CAFs were excluded from the analysis using a lineage marker cocktail (CD24, CD31, CD45, CD49f, EpCAM, LYVE-1, and TER-119). In total 128 murine tumours and 12 healthy mammary fat pads were analysed.

RESULTS

We have developed a multicolour flow cytometry strategy based on exclusion of non-CAFs and successfully employed this to explore the temporal heterogeneity of freshly isolated CAFs in the 4T1 and 4T07 mouse models of triple-negative breast cancer. Analysing 128 murine tumours, we identified 5-6 main CAF populations and numerous minor ones based on the analysis of αSMA, FAPα, PDGFRα, PDGFRβ, CD26, and PDPN. All markers showed temporal changes with a distinct switch from primarily PDGFRα+ fibroblasts in healthy mammary tissue to predominantly PDGFRβ+ CAFs in tumours. CD26+ CAFs emerged as a large novel subpopulation, only matched by FAPα+ CAFs in abundance.

CONCLUSION

We demonstrate that multiple subpopulations of CAFs co-exist in murine triple negative breast cancer, and that the abundance and dynamics for each marker differ depending on tumour type and time. Our results form the foundation needed to isolate and characterise specific CAF populations, and ultimately provide an opportunity to therapeutically target specific CAF subpopulations.

Hypoxia-Driven Oncometabolite L-2HG Maintains Stemness-Differentiation Balance and Facilitates Immune Evasion in Pancreatic Cancer

In pancreatic cancer, the robust fibroinflammatory stroma contributes to immune suppression and renders tumors hypoxic, altering intratumoral metabolic pathways and leading to poor survival. One metabolic enzyme activated during hypoxia is lactate dehydrogenase A (LDHA). As a result of its promiscuous activity under hypoxia, LDHA produces L-2 hydroxyglutarate (L-2HG), an epigenetic modifier, that regulates the tumor transcriptome. However, the role of L-2HG in remodeling the pancreatic tumor microenvironment is not known. Here we used mass spectrometry to detect L-2HG in serum samples from patients with pancreatic cancer, comprising tumor cells as well as stromal cells. Both hypoxic pancreatic tumors as well as serum from patients with pancreatic cancer accumulated L-2HG as a result of promiscuous activity of LDHA. This abnormally accumulated L-2HG led to H3 hypermethylation and altered gene expression, which regulated a critical balance between stemness and differentiation in pancreatic tumors. Secreted L-2HG inhibited T-cell proliferation and migration, suppressing antitumor immunity. In a syngeneic orthotopic model of pancreatic cancer, inhibition of LDH with GSK2837808A decreased L-2HG, induced tumor regression, and sensitized tumors to anti-PD1 therapy. In conclusion, hypoxia-mediated promiscuous activity of LDH produces L-2HG in pancreatic tumor cells, regulating the stemness-differentiation balance and contributing to immune evasion. Targeting LDH can be developed as a potential therapy to sensitize pancreatic tumors to checkpoint inhibitor therapy. SIGNIFICANCE: This study shows that promiscuous LDH activity produces L-2HG in pancreatic tumor and stromal cells, modulating tumor stemness and immune cell function and infiltration in the tumor microenvironment.

ZBP1 not RIPK1 mediates tumor necroptosis in breast cancer

Tumor necrosis happens commonly in advanced solid tumors. We reported that necroptosis plays a major role in tumor necrosis. Although several key necroptosis regulators including receptor interacting protein kinase 1 (RIPK1) have been identified, the regulation of tumor necroptosis during tumor development remains elusive. Here, we report that Z-DNA-binding protein 1 (ZBP1), not RIPK1, mediates tumor necroptosis during tumor development in preclinical cancer models. We found that ZBP1 expression is dramatically elevated in necrotic tumors. Importantly, ZBP1, not RIPK1, deletion blocks tumor necroptosis during tumor development and inhibits metastasis. We showed that glucose deprivation triggers ZBP1-depedent necroptosis in tumor cells. Glucose deprivation causes mitochondrial DNA (mtDNA) release to the cytoplasm and the binding of mtDNA to ZBP1 to activate MLKL in a BCL-2 family protein, NOXA-dependent manner. Therefore, our study reveals ZBP1 as the key regulator of tumor necroptosis and provides a potential drug target for controlling tumor metastasis.

Gain-of-function p53 protein transferred via small extracellular vesicles promotes conversion of fibroblasts to a cancer-associated phenotype

Tumor and stromal interactions consist of reciprocal signaling through cytokines, growth factors, direct cell-cell interactions, and extracellular vesicles (EVs). Small EVs (≤200 nm) have been considered critical messengers of cellular communication during tumor development. Here, we demonstrate that gain-of-function (GOF) p53 protein can be packaged into small EVs and transferred to fibroblasts. GOF p53 protein is selectively bound by heat shock protein 90 (HSP90), a chaperone protein, and packaged into small EVs. Inhibition of HSP90 activity blocks packaging of GOF, but not wild-type, p53 in small EVs. GOF p53-containing small EVs result in their conversion to cancer-associated fibroblasts. In vivo studies reveal that GOF p53-containing small EVs can enhance tumor growth and promote fibroblast transformation into a cancer-associated phenotype. These findings provide a better understanding of the complex interactions between cancer and stromal cells and may have therapeutic implications.

Ma et al. report that gain-of-function (GOF) p53 protein can be packaged into small EVs and transferred to stromal fibroblasts. The packaging of GOF p53 into small EVs is regulated by HSP90. Small EVs with GOF p53 activate Nrf2-mediated pathways in fibroblasts and induce their conversion to a cancer-associated phenotype.

Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer

Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.

Survivin in breast cancer-derived exosomes activates fibroblasts by up-regulating SOD1, whose feedback promotes cancer proliferation and metastasis

Cancer-associated fibroblasts (CAFs) play a critical role in the coevolution of breast tumor cells and their microenvironment by modifying cellular compartments and regulating cancer cell functions via stromal-epithelial dialogue. However, the relationship and interaction between stromal and epithelial cells is still poorly understood. Herein, we revealed that breast cancer cells have a stronger ability to activate fibroblasts and transform them into myofibroblasts (CAF-like) than normal breast epithelial cells, and this stronger ability occurs through paracrine signaling. In turn, myofibroblasts promote the proliferation, epithelial-to-mesenchymal transition (EMT), and stemness of breast cancer cells. Detailed regulatory mechanisms showed that, compared with normal cells, Survivin is overexpressed in breast cancer cells and secreted extracellularly in the form of exosomes, which are then internalized by fibroblasts. Breast cancer cell-derived survivin up-regulates SOD1 expression in fibroblasts and then converts them into myofibroblasts, conversely inducing breast cancer progression in vitro and in vivo Thus, our results indicate that survivin acts as an activator of the tumor microenvironment and that SOD1 up-regulation in fibroblasts can promote breast cancer progression. These results suggest that targeting survivin and SOD1 may be a potential therapeutic strategy for breast cancer.

Targeting tumor-intrinsic hexosamine biosynthesis sensitizes pancreatic cancer to anti-PD1 therapy

Pancreatic ductal adenocarcinoma (PDAC) is considered to be a highly immunosuppressive and heterogenous neoplasm. Despite improved knowledge regarding the genetic background of the tumor and better understanding of the tumor microenvironment, immune checkpoint inhibitor therapy (targeting CTLA4, PD1, PDL1) has not been very successful against PDAC. The robust desmoplastic stroma, along with an extensive extracellular matrix (ECM) that is rich in hyaluronan, plays an integral role in this immune evasion. Hexosamine biosynthesis pathway (HBP), a shunt pathway of glycolysis, is a metabolic node in cancer cells that can promote survival pathways on the one hand and influence the hyaluronan synthesis in the ECM on the other. The rate-limiting enzyme of the pathway, glutamine-fructose amidotransferase 1 (GFAT1), uses glutamine and fructose 6-phosphate to eventually synthesize uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). In the current manuscript, we targeted this glutamine-utilizing enzyme by a small molecule glutamine analog (6-diazo-5-oxo-l-norleucine [DON]). Our results showed that DON decreased the self-renewal potential and metastatic ability of tumor cells. Further, treatment with DON decreased hyaluronan and collagen in the tumor microenvironment, leading to an extensive remodeling of the ECM and an increased infiltration of CD8+ T cells. Additionally, treatment with DON sensitized pancreatic tumors to anti-PD1 therapy, resulting in tumor regression and prolonged survival.

Single-Cell Transcriptomic Analysis of Tumor-Derived Fibroblasts and Normal Tissue-Resident Fibroblasts Reveals Fibroblast Heterogeneity in Breast Cancer

Cancer-associated fibroblasts (CAFs) are a prominent stromal cell type in solid tumors and molecules secreted by CAFs play an important role in tumor progression and metastasis. CAFs coexist as heterogeneous populations with potentially different biological functions. Although CAFs are a major component of the breast cancer stroma, molecular and phenotypic heterogeneity of CAFs in breast cancer is poorly understood. In this study, we investigated CAF heterogeneity in triple-negative breast cancer (TNBC) using a syngeneic mouse model, BALB/c-derived 4T1 mammary tumors. Using single-cell RNA sequencing (scRNA-seq), we identified six CAF subpopulations in 4T1 tumors including: 1) myofibroblastic CAFs, enriched for α-smooth muscle actin and several other contractile proteins; 2) ‘inflammatory’ CAFs with elevated expression of inflammatory cytokines; and 3) a CAF subpopulation expressing major histocompatibility complex (MHC) class II proteins that are generally expressed in antigen-presenting cells. Comparison of 4T1-derived CAFs to CAFs from pancreatic cancer revealed that these three CAF subpopulations exist in both tumor types. Interestingly, cells with inflammatory and MHC class II-expressing CAF profiles were also detected in normal breast/pancreas tissue, suggesting that these phenotypes are not tumor microenvironment-induced. This work enhances our understanding of CAF heterogeneity, and specifically targeting these CAF subpopulations could be an effective therapeutic approach for treating highly aggressive TNBCs.

Cell type-specific transcriptomics of esophageal adenocarcinoma as a scalable alternative for single cell transcriptomics

Single‐cell transcriptomics have revolutionized our understanding of the cell composition of tumors and allowed us to identify new subtypes of cells. Despite rapid technological advancements, single‐cell analysis remains resource‐intense hampering the scalability that is required to profile a sufficient number of samples for clinical associations. Therefore, more scalable approaches are needed to understand the contribution of individual cell types to the development and treatment response of solid tumors such as esophageal adenocarcinoma where comprehensive genomic studies have only led to a small number of targeted therapies. Due to the limited treatment options and late diagnosis, esophageal adenocarcinoma has a poor prognosis. Understanding the interaction between and dysfunction of individual cell populations provides an opportunity for the development of new interventions. In an attempt to address the technological and clinical needs, we developed a protocol for the separation of esophageal carcinoma tissue into leukocytes (CD45+), epithelial cells (EpCAM+), and fibroblasts (two out of PDGFRα, CD90, anti‐fibroblast) by fluorescence‐activated cell sorting and subsequent RNA sequencing. We confirm successful separation of the three cell populations by mapping their transcriptomic profiles to reference cell lineage expression data. Gene‐level analysis further supports the isolation of individual cell populations with high expression of CD3, CD4, CD8, CD19, and CD20 for leukocytes, CDH1 and MUC1 for epithelial cells, and FAP, SMA, COL1A1, and COL3A1 for fibroblasts. As a proof of concept, we profiled tumor samples of nine patients and explored expression differences in the three cell populations between tumor and normal tissue. Interestingly, we found that angiogenesis‐related genes were upregulated in fibroblasts isolated from tumors compared with normal tissue. Overall, we suggest our protocol as a complementary and more scalable approach compared with single‐cell RNA sequencing to investigate associations between clinical parameters and transcriptomic alterations of specific cell populations in esophageal adenocarcinoma.

Generation of an Fsp1 (fibroblast-specific protein 1)-Flpo transgenic mouse strain

Recombination systems represent a major breakthrough in the field of genetic model engineering. The Flp recombinases (Flp, Flpe, and Flpo) bind and cleave DNA Frt sites. We created a transgenic mouse strain ([Fsp1‐Flpo]) expressing the Flpo recombinase in fibroblasts. This strain was obtained by random insertion inside mouse zygotes after pronuclear injection. Flpo expression was placed under the control of the promoter of Fsp1 (fibroblast‐specific protein 1) gene, whose expression starts after gastrulation at Day 8.5 in cells of mesenchymal origin. We verified the correct expression and function of the Flpo enzyme by several ex vivo and in vivo approaches. The [Fsp1‐Flpo] strain represents a genuine tool to further target the recombination of transgenes with Frt sites specifically in cells of mesenchymal origin or with a fibroblastic phenotype.

In search of definitions: Cancer-associated fibroblasts and their markers

The tumor microenvironment has been identified as one of the driving factors of tumor progression and invasion. Inside this microenvironment, cancer-associated fibroblasts (CAFs), a type of perpetually activated fibroblasts, have been implicated to have a strong tumor-modulating effect and play a key role in areas such as drug resistance. Identification of CAFs has typically been carried based on the expression of various "CAF markers", such as fibroblast activation protein alpha (FAP) and alpha smooth muscle actin (αSMA), which separates them from the larger pool of fibroblasts present in the body. However, as outlined in this Review, the expression of various commonly used fibroblast markers is extremely heterogeneous and varies strongly between different CAF subpopulations. As such, novel selection methods based on cellular function, as well as further characterizing research, are vital for the standardization of CAF identification in order to improve the cross-applicability of different research studies in the field. The aim of this review is to give a thorough overview of the commonly used fibroblast markers in the field and their various strengths and, more importantly, their weaknesses, as well as to highlight potential future avenues for CAF identification and targeting.

Cancer-associated fibroblasts as a potential target in oncology therapy

Tumors make up a complex environment that consists of intensive proliferating cancer cells surrounded by normal cells. Fibroblasts recruited by cancer termed CAFs, are one of the major cell groups within the reactive stroma of the most common tumors. Because of the crosstalk between quiescent fibroblasts and cancer cells, fibroblasts undergo phenotypic transition and acquire new functions that have been “forced by a tumor”. CAFs affect the development of the drug resistance and cancer progression as they are involved in the growth of cancers, neoangiogenesis, immune evasion and metastatic colonisation in distant organs. Fibroblast-directed therapy offers the opportunity to prevent initiation, progression and metastasis of many invasive tumors. The current studies on CAF-based therapy focus on two strategies. The first strategy leads to the elimination of CAFs and the neutralization of their released factors and the second aims at reverting the CAF-phenotype to a “normal” fibroblast-phenotype. Although the results of preclinical studies conducted on cell cultures and animal models indicate that therapy aimed at reversion or inhibition CAFs function seem to be a promising therapeutic target, available clinical studies have not yet confirmed this. Nevertheless, it is necessary to underline that until now CAF-based therapy has been used in patients with advanced cancer and there is no clinical study using such therapy in the early stage of cancer. The available data also indicates that CAF-based therapy could be used in combination with common anticancer drugs to increase their effectiveness. Therefore, further studies on the usefulness of the proposed CAF-based therapy are needed.

NLRP3 inflammasome in fibroblasts links tissue damage with inflammation in breast cancer progression and metastasis

Cancer-Associated Fibroblasts (CAFs) were shown to orchestrate tumour-promoting inflammation in multiple malignancies, including breast cancer. However, the molecular pathways that govern the inflammatory role of CAFs are poorly characterised. In this study we found that fibroblasts sense damage-associated molecular patterns (DAMPs), and in response activate the NLRP3 inflammasome pathway, resulting in instigation of pro-inflammatory signalling and secretion of IL-1β. This upregulation was evident in CAFs in mouse and in human breast carcinomas. Moreover, CAF-derived inflammasome signalling facilitated tumour growth and metastasis, which was attenuated when NLRP3 or IL-1β were specifically ablated. Functionally, CAF-derived inflammasome promoted tumour progression and metastasis by modulating the tumour microenvironment towards an immune suppressive milieu and by upregulating the expression of adhesion molecules on endothelial cells. Our findings elucidate a mechanism by which CAFs promote breast cancer progression and metastasis, by linking the physiological tissue damage response of fibroblasts with tumour-promoting inflammation.

Method of localized removal of cells using a bolt-clamped Langevin transducer with an ultrasonic horn

Cell isolation by eliminating undesirable cell aggregations or colonies with low activity is essential to improve cell culture efficiency. Moreover, when creating tissues from induced pluripotent stem cells, residual undifferentiated cells must be removed to prevent tumor formation in vivo. Here, we evaluated the use of ultrasonic irradiation, which can apply energy locally without contact, and proposed a method to eliminate cells in a small area of culture by ultrasonic irradiation from a Langevin transducer. We constructed a device that incorporated a bolt-clamped 19.84 kHz Langevin transducer with an ultrasonic horn and determined the optimal conditions for stable elimination of cells in small areas of a 35-mm culture dish. The optimal conditions were as follows: number of cycles = 400, clearance distance = 1 mm, volume of medium = 4 mL, and distance from the center of culture surface = 0 mm. The mean cell elimination area under these conditions was 0.097 mm². We also evaluated the viability of neighboring cells after ultrasonic irradiation by fluorescent staining and found that most cells around the elimination area survived. These findings suggest that the proposed method has potential for localized elimination of cells without the need for contact with the cell surface.

Tumor-secreted extracellular vesicles promote the activation of cancer-associated fibroblasts via the transfer of microRNA-125b

Tumour cells release large quantities of extracellular vesicles (EVs) to mediate their interactions with other cells in the tumour microenvironment. To identify host cells that naturally take up EVs from tumour cells, we created breast cancer cell lines secreting fluorescent EVs. These fluorescent EVs are taken up most robustly by fibroblasts within the tumour microenvironment. RNA sequencing indicated that miR-125b is one of the most abundant microRNAs secreted by mouse triple-negative breast cancer 4T1 and 4TO7 cells. Treatment with 4T1 EVs leads to an increase in fibroblast activation in isogenic 4TO7 tumours, which is reversed by blocking miR-125b in 4T1 EVs; hence, miR-125b delivery by EVs is responsible for fibroblast activation in mouse tumour models. miR-125b is also secreted by human breast cancer cells and the uptake of EVs from these cells significantly increases cellular levels of miR-125b and expression of multiple cancer-associated fibroblast markers in resident fibroblasts. Overexpression of miR-125b in both mouse and human fibroblasts leads to an activated phenotype similar to the knockdown of established miR-125b target mRNAs. These data indicate that miR-125b is transferred through EVs from breast cancer cells to normal fibroblasts within the tumour microenvironment and contributes to their development into cancer-associated fibroblasts.

Inter- and intra-tumoural heterogeneity in cancer-associated fibroblasts of human pancreatic ductal adenocarcinoma

Cancer‐associated fibroblasts (CAF) are orchestrators of the pancreatic ductal adenocarcinoma (PDAC) microenvironment. Stromal heterogeneity may explain differential pathophysiological roles of the stroma (pro‐ versus anti‐tumoural) in PDAC. We hypothesised that multiple CAF functional subtypes exist in PDAC, that contribute to stromal heterogeneity through interactions with cancer cells. Using molecular and functional analysis of patient‐derived CAF primary cultures, we demonstrated that human PDAC‐derived CAFs display a high level of inter‐ and intra‐tumour heterogeneity. We identified at least four subtypes of CAFs based on transcriptomic analysis, and propose a classification for human PDAC‐derived CAFs (pCAFassigner). Multiple CAF subtypes co‐existed in individual patient samples. The presence of these CAF subtypes in bulk tumours was confirmed using publicly available gene expression profiles, and immunostainings of CAF subtype markers. Each subtype displayed specific phenotypic features (matrix‐ and immune‐related signatures, vimentin and α‐smooth muscle actin expression, proliferation rate), and was associated with an assessable prognostic impact. A prolonged exposure of non‐tumoural pancreatic stellate cells to conditioned media from cancer cell lines (cancer education experiment) induced a CAF‐like phenotype, including loss of capacity to revert to quiescence and an increase in the expression of genes related to CAF subtypes B and C. This classification demonstrates molecular and functional inter‐ and intra‐tumoural heterogeneity of CAFs in human PDAC. Our subtypes overlap with those identified from single‐cell analyses in other cancers, and pave the way for the development of therapies targeting specific CAF subpopulations in PDAC. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

ATF3 and JDP2 deficiency in cancer associated fibroblasts promotes tumor growth via SDF-1 transcription

The activating transcription factor 3 (ATF3) and the c-Jun dimerization protein 2 (JDP2) are members of the basic leucine zipper (bZIP) family of transcription factors. These proteins share a high degree of homology and both can activate or repress transcription. Deficiency of either one of them in the non-cancer host cells was shown to reduce metastases. As ATF3 and JDP2 compensate each other's function, we studied the double deficiency of ATF3 and JDP2 in the stromal tumor microenvironment. Here, we show that mice with ATF3 and JDP2 double deficiency (designated thereafter dKO) developed larger tumors with high vascular perfusion and increased cell proliferation rate compared to wild type (WT) mice. We further identify that the underlying mechanism involves tumor associated fibroblasts which secrete high levels of stromal cell-derived factor 1 (SDF-1) in dKO fibroblasts. SDF-1 depletion in dKO fibroblasts dampened tumor growth and blood vessel perfusion. Furthermore, ATF3 and JDP2 were found to regulate SDF-1 transcription and secretion in fibroblasts, a phenomenon that is potentiated in the presence of cancer cells. Collectively, our results suggest that ATF3 and JDP2 regulate the expression of essential tumor promoting factors expressed by fibroblasts within the tumor microenvironment, and thus restrain tumor growth.

CXCL1 Derived from Mammary Fibroblasts Promotes Progression of Mammary Lesions to Invasive Carcinoma through CXCR2 Dependent Mechanisms

With improved screening methods, the numbers of abnormal breast lesions diagnosed in women have been increasing over time. However, it remains unclear whether these breast lesions will develop into invasive cancers. To more effectively predict the outcome of breast lesions and determine a more appropriate course of treatment, it is important to understand the underlying mechanisms that regulate progression of non-invasive lesions to invasive breast cancers. A hallmark of invasive breast cancers is the accumulation of fibroblasts. Fibroblast proliferation and activation in the mammary gland is in part regulated by the Transforming Growth Factor beta1 pathway (TGF-β). In animal models, TGF-β suppression of CCL2 and CXCL1 chemokine expression is associated with metastatic progression of mammary carcinomas. Here, we show that transgenic overexpression of the Polyoma middle T viral antigen in the mouse mammary gland of C57BL/6 mice results in slow growing non-invasive lesions that progress to invasive carcinomas in a stage dependent manner. Invasive carcinomas are associated with accumulation of fibroblasts that show decreased TGF-β expression and high levels of CXCL1, but not CCL2. Using co-transplant models, we show that decreased TGF-β signaling in fibroblasts contribute to mammary carcinoma progression through enhancement of CXCL1/CXCR2 dependent mechanisms. Using cell culture models, we show that CXCL1 mediated mammary carcinoma cell invasion through NF-κB, AKT, Stat3 and p42/44MAPK dependent mechanisms. These studies provide novel mechanistic insight into the progression of pre-invasive lesions and identify new stromal biomarkers, with important prognostic implications.

Bone marrow-derived fibroblasts are a functionally distinct stromal cell population in breast cancer

Raz et al. demonstrate that the expression of PDGFRα distinguishes two functional CAF populations in breast tumors and lung metastases and identify a subpopulation of CAFs that are specifically recruited to the tumor microenvironment from mesenchymal stromal cells in the BM.

Cancer-associated fibroblasts (CAFs) are highly prominent in breast tumors, but their functional heterogeneity and origin are still largely unresolved. We report that bone marrow (BM)–derived mesenchymal stromal cells (MSCs) are recruited to primary breast tumors and to lung metastases and differentiate to a distinct subpopulation of CAFs. We show that BM-derived CAFs are functionally important for tumor growth and enhance angiogenesis via up-regulation of Clusterin. Using newly generated transgenic mice and adoptive BM transplantations, we demonstrate that BM-derived fibroblasts are a substantial source of CAFs in the tumor microenvironment. Unlike resident CAFs, BM-derived CAFs do not express PDGFRα, and their recruitment resulted in a decrease in the percentage of PDGFRα-expressing CAFs. Strikingly, decrease in PDGFRα in breast cancer patients was associated with worse prognosis, suggesting that BM-derived CAFs may have deleterious effects on survival. Therefore, PDGFRα expression distinguishes two functionally unique CAF populations in breast tumors and metastases and may have important implications for patient stratification and precision therapeutics.

Divergent Matrix-Remodeling Strategies Distinguish Developmental from Neoplastic Mammary Epithelial Cell Invasion Programs

Metastasizing breast carcinoma cells have been hypothesized to mobilize tissue-invasive activity by co-opting the proteolytic systems employed by normal mammary epithelial cells undergoing branching morphogenesis. However, the critical effectors underlying morphogenesis remain unidentified, and their relationship to breast cancer invasion programs is yet to be established. Here, we identify the membrane-anchored matrix metalloproteinase, Mmp14/MT1-MMP, but not the closely related proteinase Mmp15/MT2-MMP, as the dominant proteolytic effector of both branching morphogenesis and carcinoma cell invasion in vivo. Unexpectedly, however, epithelial cell-specific targeting of Mmp14/MT1-MMP in the normal mammary gland fails to impair branching, whereas deleting the proteinase in carcinoma cells abrogates invasion, preserves matrix architecture, and completely blocks metastasis. By contrast, in the normal mammary gland, extracellular matrix remodeling and morphogenesis are ablated only when Mmp14/MT1-MMP expression is specifically deleted from the periductal stroma. Together, these findings uncover the overlapping but divergent strategies that underlie developmental versus neoplastic matrix remodeling programs.

The effect of anti-inflammatory and antifibrotic agents on fibroblasts obtained from arthrofibrotic tissue: An in vitro and in vivo study

Objectives

The aims of this study were to determine whether the administration of anti-inflammatory and antifibrotic agents affect the proliferation, viability, and expression of markers involved in the fibrotic development of the fibroblasts obtained from arthrofibrotic tissue in vitro, and to evaluate the effect of the agents on arthrofibrosis prevention in vivo.

Methods

Dexamethasone, diclofenac, and decorin, in different concentrations, were employed to treat fibroblasts from arthrofibrotic tissue (AFib). Cell proliferation was measured by DNA quantitation, and viability was analyzed by Live/Dead staining. The levels of procollagen type I N-terminal propeptide (PINP) and procollagen type III N-terminal propeptide (PIIINP) were evaluated with enzyme-linked immunosorbent assay (ELISA) kits. In addition, the expressions of fibrotic markers were detected by real-time polymerase chain reaction (PCR). Fibroblasts isolated from healthy tissue (Fib) served as control. Further, a rabbit model of joint contracture was used to evaluate the antifibrotic effect of the three different agents.

Results

Dexamethasone maintained the viability and promoted the proliferation of AFib. Diclofenac decreased the viability and inhibited the cell proliferation during the first week of cultivation. However, decorin inhibited AFib proliferation and downregulated the expressions of fibrotic markers. Additionally, decorin could improve the flexion contracture angle and inhibit the deposition of interstitial matrix components in the rabbit joint model.

Conclusion

Decorin decreased the expression of myofibroblast markers in AFib, inhibited the proliferation of AFib, and prevented the initial procedure of arthrofibrosis in vivo, suggesting that decorin could be a promising treatment to inhibit the development of arthrofibrosis.Cite this article: X. Tang, S. Teng, M. Petri, C. Krettek, C. Liu, M. Jagodzinski. The effect of anti-inflammatory and antifibrotic agents on fibroblasts obtained from arthrofibrotic tissue: An in vitro and in vivo study. Bone Joint Res 2018;7:213-222. DOI: 10.1302/2046-3758.73.BJR-2017-0219.R2.

Inhibiting tumor necrosis factor-alpha diminishes desmoplasia and inflammation to overcome chemoresistance in pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common cancer death reasons. Anti-tumor necrosis factor-alpha (TNF-α) antibodies have shown promising effects in PDAC pre-clinical models. However, the prognostic values of TNF-α, underlying mechanisms by which anti-TNF-α treatments inhibit PDAC, and potential synergistic effects of anti-TNF-α treatments with chemotherapy are still unclear.

Results and Methods

To identify the targeting values of TNF-α in PDAC, we measured TNF-α expression in different stages of PDAC initiation and evaluated its prognostic significance in a pancreatic cancer cohort. We found that TNF-α expression elevated in PDAC initiation process, and high expression of TNF-α was an independent prognostic marker of poor survival. We further evaluated anti-tumor effects of anti-TNF-α treatments in PDAC. Anti-TNF-α treatments resulted in decreased cell viability in both PDAC tumor cells and pancreatic satellite cells in similar dose in vitro. In vivo, anti-TNF-α treatments showed effects in reducing desmoplasia and the tumor promoting inflammatory microenvironment in PDAC. Combination of anti-TNF-α treatments with chemotherapy partly overcame chemoresistance of PDAC tumor cells and prolonged the survival of PDAC mouse model.

Conclusions

In conclusion, our findings indicated that TNF-α in PDAC can be a prognostic and therapeutic target. Inhibition of TNF-α synergized with chemotherapy in PDAC resulted in better pre-clinical responses via killing tumor cells as well as diminishing desmoplasia and inflammation in PDAC tumor stroma.

PTEN Loss Promotes Intratumoral Androgen Synthesis and Tumor Microenvironment Remodeling via Aberrant Activation of RUNX2 in Castration-Resistant Prostate Cancer

Purpose: Intratumoral androgen synthesis (IAS) is a key mechanism promoting androgen receptor (AR) reactivation and antiandrogen resistance in castration-resistant prostate cancer (CRPC). However, signaling pathways driving aberrant IAS remain poorly understood.Experimental Design: The effect of components of the AKT-RUNX2-osteocalcin (OCN)-GPRC6A-CREB signaling axis on expression of steroidogenesis genes CYP11A1 and CYP17A1 and testosterone level were examined in PTEN-null human prostate cancer cell lines. Pten knockout mice were used to examine the effect of Runx2 heterozygous deletion or abiraterone acetate (ABA), a prodrug of the CYP17A1 inhibitor abiraterone on Cyp11a1 and Cyp17a1 expression, testosterone level and tumor microenvironment (TME) remodeling in vivoResults: We uncovered that activation of the AKT-RUNX2-OCN-GPRC6A-CREB signaling axis induced expression of CYP11A1 and CYP17A1 and testosterone production in PTEN-null prostate cancer cell lines in culture. Deletion of Runx2 in Pten homozygous knockout prostate tumors decreased Cyp11a1 and Cyp17a1 expression, testosterone level, and tumor growth in castrated mice. ABA treatment also inhibited testosterone synthesis and alleviated Pten loss-induced tumorigenesis in vivoPten deletion induced TME remodeling, but Runx2 heterozygous deletion or ABA treatment reversed the effect of Pten loss by decreasing expression of the collagenase Mmp9.Conclusions: Abnormal RUNX2 activation plays a pivotal role in PTEN loss-induced IAS and TME remodeling, suggesting that the identified signaling cascade represents a viable target for effective treatment of PTEN-null prostate cancer, including CRPC. Clin Cancer Res; 24(4); 834-46. ©2017 AACR.

Saa3 is a key mediator of the protumorigenic properties of cancer-associated fibroblasts in pancreatic tumors

Pancreatic ductal adenocarcinoma (PDAC) is characterized by the presence of abundant desmoplastic stroma primarily composed of cancer-associated fibroblasts (CAFs). It is generally accepted that CAFs stimulate tumor progression and might be implicated in drug resistance and immunosuppression. Here, we have compared the transcriptional profile of PDGFRα⁺ CAFs isolated from genetically engineered mouse PDAC tumors with that of normal pancreatic fibroblasts to identify genes potentially implicated in their protumorigenic properties. We report that the most differentially expressed gene, Saa3, a member of the serum amyloid A (SAA) apolipoprotein family, is a key mediator of the protumorigenic activity of PDGFRα⁺ CAFs. Whereas Saa3-competent CAFs stimulate the growth of tumor cells in an orthotopic model, Saa3-null CAFs inhibit tumor growth. Saa3 also plays a role in the cross talk between CAFs and tumor cells. Ablation of Saa3 in pancreatic tumor cells makes them insensitive to the inhibitory effect of Saa3-null CAFs. As a consequence, germline ablation of Saa3 does not prevent PDAC development in mice. The protumorigenic activity of Saa3 in CAFs is mediated by Mpp6, a member of the palmitoylated membrane protein subfamily of the peripheral membrane-associated guanylate kinases (MAGUK). Finally, we interrogated whether these observations could be translated to a human scenario. Indeed, SAA1, the ortholog of murine Saa3, is overexpressed in human CAFs. Moreover, high levels of SAA1 in the stromal component correlate with worse survival. These findings support the concept that selective inhibition of SAA1 in CAFs may provide potential therapeutic benefit to PDAC patients.

Targeting the Myofibroblastic Cancer-Associated Fibroblast Phenotype Through Inhibition of NOX4

Background

Cancer-associated fibroblasts (CAFs) are tumor-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed.

Methods

CAF accumulation and prognostic significance in head and neck cancer (oral, n = 260; oropharyngeal, n = 271), and colorectal cancer (n = 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4's role in CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypic culture assays, and in vivo, using xenograft (n = 9-15 per group) and isograft (n = 6 per group) tumor models. All statistical tests were two-sided.

Results

Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specific survival rates in each cancer type analyzed (hazard ratios [HRs] = 1.69-7.25, 95% confidence intervals [CIs] = 1.11 to 31.30, log-rank P ≤ .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significant upregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic-CAFs (r = 0.65-0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic-CAF phenotype ex vivo (54.3% decrease in α-smooth muscle actin [α-SMA], 95% CI = 10.6% to 80.9%, P = .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%-79.0% decrease in α-SMA across different models, P ≤ .02) and slow tumor growth (30.6%-64.0% decrease across different models, P ≤ .04).

Conclusions

These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types.

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

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

Reprogramming pancreatic stellate cells via p53 activation: A putative target for pancreatic cancer therapy

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely dense fibrotic stroma, which contributes to tumor growth, metastasis, and drug resistance. During tumorigenesis, quiescent pancreatic stellate cells (PSCs) are activated and become major contributors to fibrosis, by increasing growth factor signaling and extracellular matrix deposition. The p53 tumor suppressor is known to restrict tumor initiation and progression through cell autonomous mechanisms including apoptosis, cell cycle arrest, and senescence. There is growing evidence that stromal p53 also exerts anti-tumor activity by paracrine mechanisms, though a role for stromal p53 in PDAC has not yet been described. Here, we demonstrate that activation of stromal p53 exerts anti-tumor effects in PDAC. We show that primary cancer-associated PSCs (caPSCs) isolated from human PDAC express wild-type p53, which can be activated by the Mdm2 antagonist Nutlin-3a. Our work reveals that p53 acts as a major regulator of PSC activation and as a modulator of PDAC fibrosis. In vitro, p53 activation by Nutlin-3a induces profound transcriptional changes, which reprogram activated PSCs to quiescence. Using immunofluorescence and lipidomics, we have also found that p53 activation induces lipid droplet accumulation in both normal and tumor-associated fibroblasts, revealing a previously undescribed role for p53 in lipid storage. In vivo, treatment of tumor-bearing mice with the clinical form of Nutlin-3a induces stromal p53 activation, reverses caPSCs activation, and decreases fibrosis. All together our work uncovers new functions for stromal p53 in PDAC.

Tumor microenvironment heterogeneity: challenges and opportunities

The tumor microenvironment (TME) has been recognized as an integral component of malignancies in breast and prostate tissues, contributing in confounding ways to tumor progression, metastasis, therapy resistance and disease recurrence. Major components of the TME are immune cells, fibroblasts, pericytes, endothelial cells, mesenchymal stroma/stem cells (MSCs), and extracellular matrix (ECM) components. Herein, we discuss the molecular and cellular heterogeneity within the TME and how this presents unique challenges and opportunities for treating breast and prostate cancers.

Stroma-derived Fibrinogen-like Protein 2 Activates Cancer-associated Fibroblasts to Promote Tumor Growth in Lung Cancer

Fibrinogen-like protein 2 (Fgl2), a member of the fibrinogen super family, is a pleiotropic cytokine that impacts diverse cellular functions. Previous studies have shown that tumor cell-derived Fgl2 promotes tumorigenesis and metastasis in immune-deficient mice, and it also functions as an immune-suppressive modulator in glioblastoma multiform (GMB). This study aimed to evaluate whether and how tumor stroma-derived Fgl2 affects tumorigenesis and tumor progression. We established the syngeneic transplantable Lewis lung carcinoma (LLC) model in Fgl2-knock-out (Fgl2-KO) mice and we found that deficiency of host Fgl2 is associated with reduced growth of syngeneic LLC tumors. Furthermore, we confirmed that host Fgl2 deficiency significantly decreased the accumulation of myeloid-derived suppressor cells (MDSCs) through down-regulation of chemokine (C-X-C motif) ligand 12 (CXCL12) expression. More importantly, we demonstrated that Fgl2 induced an activated and pro-tumorigenic phenotype of cancer-associated fibroblasts (CAFs) which are the principal source of CXCL12 in the tumor microenvironment (TME). Our results present a novel role of stroma-derived Fgl2 in CAF activation and function, suggesting that Fgl2 is an effective therapeutic target for treating lung cancer.

Micro-RNA-21 Regulates Cancer-Associated Fibroblast-Mediated Drug Resistance in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths due to its highly aggressive biological nature and resistance to chemotherapy. Previous studies indicate that miR-21 is an important regulator in the activation of cancer-associated fibroblasts (CAFs). However, whether miR-21 in CAFs would regulate PDAC’s tumor microenvironment and lead to drug resistance remain unknown. In this study, we evaluated the relationship between CAF activation, miR-21 expression, and drug resistance using tumor samples from PDAC patients. We changed the miR-21 expression level in CAFs and tested its roles in regulating the function of CAFs. In addition, we explored the roles of miR-21 in CAFs in the development of PDAC using an animal model. We found that PDAC patients who were resistant to gemcitabine treatment tended to have higher miR-21 expression and more activated CAFs. An in vitro study showed that CAFs with high miR-21 expression had elevated MMP-3, MMP-9, PDGF, and CCL-7 expression and promoted the invasion of PDAC cell lines. miR-21 overexpression also contributed to the activation of CAFs by regulating the PDCD4 gene. The in vivo study showed that upregulating miR-21 in CAFs promoted PDAC desmoplasia and increased its drug resistance to gemcitabine treatment, but downregulating miR-21 in CAFs suppressed desmoplasia and enhanced the effect of gemcitabine. We concluded that miR-21 promoted the activation of CAFs and contributed to the drug resistance of PDAC.

Fibroblasts drive an immunosuppressive and growth-promoting microenvironment in breast cancer via secretion of Chitinase 3-like 1

Cancer-Associated Fibroblasts (CAFs) are the most prominent stromal cell type in breast tumors. CAFs promote tumor growth and metastasis by multiple mechanisms, including by mediating tumor-promoting inflammation. Immune modulation in the tumor microenvironment plays a central role in determining disease outcome. However, the functional interactions of CAFs with immune cells are largely unknown. Here we report a novel signaling axis between fibroblasts, cancer cells and immune cells in breast tumors that drives an immunosuppressive microenvironment, mediated by CAF-derived Chi3L1. We demonstrate that Chi3L1 is highly upregulated in CAFs isolated from mammary tumors and pulmonary metastases of transgenic mice, and in the stroma of human breast carcinomas. Genetic ablation of Chi3L1 in fibroblasts in vivo attenuated tumor growth, macrophage recruitment and reprogramming to an M2-like phenotype, enhanced tumor infiltration by CD8⁺ and CD4⁺ T cells and promoted a Th1 phenotype. These results indicate that CAF-derived Chi3L1 promotes tumor growth and shifts the balance of the immune milieu towards type 2 immunity. Taken together, our findings implicate fibroblast-derived Chi3L1 as a novel key player in the complex reciprocal interactions of stromal cells that facilitate tumor progression and metastasis, and suggest that targeting Chi3L1 may be clinically beneficial in breast cancer.

Rapid Isolation of BMPR-IB+ Adipose-Derived Stromal Cells for Use in a Calvarial Defect Healing Model

Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own body. The ability to grow bone de novo using a patient's own cells would allow bony defects to be filled with adequate tissue without the morbidity of harvesting native bone. There is interest in the use of adipose-derived stromal cells (ASCs) as a source for tissue engineering because these are obtained from an abundant source: the patient's own adipose tissue. However, ASCs are a heterogeneous population and some subpopulations may be more effective in this application than others. Isolation of the most osteogenic population of ASCs could improve the efficiency and effectiveness of a bone engineering process. In this protocol, ASCs are obtained from subcutaneous fat tissue from a human donor. The subpopulation of ASCs expressing the marker BMPR-IB is isolated using FACS. These cells are then applied to an in vivo calvarial defect healing assay and are found to have improved osteogenic regenerative potential compared with unsorted cells.

An integrated analysis identifies STAT4 as a key regulator of ovarian cancer metastasis

Epithelial ovarian cancer (EOC) is one of the most common gynecological cancers, with diagnosis often at a late stage. Metastasis is a major cause of death in patients with EOC, but the underlying molecular mechanisms remain obscure. Here, we utilized an integrated approach to find potential key transcription factors involved in ovarian cancer metastasis and identified STAT4 as a critical player in ovarian cancer metastasis. We found that activated STAT4 was overexpressed in epithelial cells of ovarian cancer and STAT4 overexpression was associated with poor outcome of ovarian cancer patients, which promoted metastasis of ovarian cancer in both in vivo and in vitro. Although STAT4 mediated EOC metastasis via inducing epithelial-to-mesenchymal transition (EMT) of ovarian cancer cells in vivo, STAT4 failed to induce EMT directly in vitro, suggesting that STAT4 might mediate EMT process via cancer-stroma interactions. Further functional analysis revealed that STAT4 overexpression induced normal omental fibroblasts and adipose- and bone marrow-derived mesenchymal stem cells to obtain cancer-associated fibroblasts (CAF)-like features via induction of tumor-derived Wnt7a. Reciprocally, increased production of CAF-induced CXCL12, IL6 and VEGFA within tumor microenvironment could enable peritoneal metastasis of ovarian cancer via induction of EMT program. In summary, our study established a model that STAT4 promotes ovarian cancer metastasis via tumor-derived Wnt7a-induced activation of CAFs.

Tumor macrophages are pivotal constructors of tumor collagenous matrix

Tumor-associated macrophages are pivotal constructors of the tumoral ECM structure and molecular composition. In particular, they orchestrate the buildup of the tumorigenic collagenous ECM niche.

Tumor-associated macrophages (TAMs) promote tumor development, invasion, and dissemination by various mechanisms. In this study, using an orthotopic colorectal cancer (CRC) model, we found that monocyte-derived TAMs advance tumor development by the remodeling of its extracellular matrix (ECM) composition and structure. Unbiased transcriptomic and proteomic analyses of (a) TAM-abundant and -deficient tumor tissues and (b) sorted tumor-associated and -resident colonic macrophage subpopulations defined a distinct TAM-induced ECM molecular signature composed of an ensemble of matricellular proteins and remodeling enzymes they provide to the tumor microenvironment. Remarkably, many of these ECM proteins are specifically increased in human CRC versus healthy colon. Specifically, we demonstrate that although differentiating into TAMs, monocytes up-regulate matrix-remodeling programs associated with the synthesis and assembly of collagenous ECM, specifically collagen types I, VI, and XIV. This finding was further established by advanced imaging showing that TAMs instruct the deposition, cross-linking, and linearization of collagen fibers during tumor development, especially at areas of tumor invasiveness. Finally, we show that cancer-associated fibroblasts are significantly outnumbered by TAMs in this model and that their expression of collagen XIV and I is reduced by TAM deficiency. Here, we outline a novel TAM protumoral function associated with building of the collagenous ECM niche.

Targeted deactivation of cancer-associated fibroblasts by β-catenin ablation suppresses melanoma growth

Cancer-associated fibroblasts (CAFs) are the crucial components of the dynamic tumor microenvironment, which not only supports the growth and metastasis of melanoma but also contributes to drug resistance in melanoma treatment. We recently discovered that loss of β-catenin signaling deactivated stromal fibroblasts and reduced the production of paracrine factors and extracellular matrix proteins. Based on this finding, we aimed to determine whether melanoma growth could be suppressed by targeted deactivation of CAFs via β-catenin ablation using a combination of in vitro and in vivo approaches. Using an in vitro three-dimensional (3D) tumor co-culture model, we showed that β-catenin-deficient fibroblasts lost the ability to respond to melanoma cell stimulation and to support the growth of B16F10 melanoma cells. To determine the in vivo effects of CAF deactivation on melanoma growth, we designed a novel genetic approach to ablate β-catenin expression in melanoma-associated fibroblasts only after melanoma tumor was formed. As expected, our observation showed that development of B16F10 melanoma was significantly delayed when β-catenin expression was ablated in CAFs. We determined that inhibition of tumor growth was due to decreased melanoma cell proliferation and increased cell death. Further analysis revealed that CAF deactivation caused the downregulation of the MAPK/ERK signaling cascade and S and G2/M phase cell cycle arrest in B16F10 melanoma cells. Overall, our data emphasize the significance of targeting CAFs as a potential novel therapeutic approach to improve melanoma treatment by creating a tumor-suppressive microenvironment through tumor-stroma interactions.

Hypoxia and Transforming Growth Factor β Cooperate to Induce Fibulin-5 Expression in Pancreatic Cancer

The deposition of extracellular matrix (ECM) is a defining feature of pancreatic ductal adenocarcinoma (PDA), where ECM signaling can promote cancer cell survival and epithelial plasticity programs. However, ECM signaling can also limit PDA tumor growth by producing cytotoxic levels of reactive oxygen species. For example, excess fibronectin stimulation of α5β1 integrin on stromal cells in PDA results in reduced angiogenesis and increased tumor cell apoptosis because of oxidative stress. Fibulin-5 (Fbln5) is a matricellular protein that blocks fibronectin-integrin interaction and thus directly limits ECM-driven reactive oxygen species production and supports PDA progression. Compared with normal pancreatic tissue, Fbln5 is expressed abundantly in the stroma of PDA; however, the mechanisms underlying the stimulation of Fbln5 expression in PDA are undefined. Using in vitro and in vivo approaches, we report that hypoxia triggers Fbln5 expression in a TGF-β- and PI3K-dependent manner. Pharmacologic inhibition of TGF-β receptor, PI3K, or protein kinase B (AKT) was found to block hypoxia-induced Fbln5 expression in mouse embryonic fibroblasts and 3T3 fibroblasts. Moreover, tumor-associated fibroblasts from mouse PDA were also responsive to TGF-β receptor and PI3K/AKT inhibition with regard to suppression of Fbln5. In genetically engineered mouse models of PDA, therapy-induced hypoxia elevated Fbln5 expression, whereas pharmacologic inhibition of TGF-β signaling reduced Fbln5 expression. These findings offer insight into the signaling axis that induces Fbln5 expression in PDA and a potential strategy to block its production.

Dermal fibroblasts induce cell cycle arrest and block epithelial-mesenchymal transition to inhibit the early stage melanoma development

Stromal fibroblasts are an integral part of the tumor stroma and constantly interact with cancer cells to promote their initiation and progression. However, the role and function of dermal fibroblasts during the early stage of melanoma development remain poorly understood. We, therefore, designed a novel genetic approach to deactivate stromal fibroblasts at the onset of melanoma formation by targeted ablation of β-catenin. To our surprise, melanoma tumors formed from β-catenin-deficient group (B16F10 mixed with β-catenin-deficient fibroblasts) appeared earlier than tumors formed from control group (B16F10 mixed with normal dermal fibroblasts). At the end point when tumors were collected, mutant tumors were bigger and heavier than control tumors. Further analysis showed that there were fewer amounts of stromal fibroblasts and myofibroblasts inside mutant tumor stroma. Melanoma tumors from control group showed reduced proliferation, down-regulated expression of cyclin D1 and increased expression of cyclin-dependent kinase inhibitor p16, suggesting dermal fibroblasts blocked the onset of melanoma tumor formation by inducing a cell cycle arrest in B16F10 melanoma cells. Furthermore, we discovered that dermal fibroblasts prevented epithelial-mesenchymal transition in melanoma cells. Overall, our findings demonstrated that dermal fibroblasts crosstalk with melanoma cells to regulate in vivo tumor development via multiple mechanisms, and the outcomes of their reciprocal interactions depend on activation states of stromal fibroblasts and stages of melanoma development.