Primary Cancer-associated Fibroblasts Research Articles

Abstract B009: Characterization and CRISPR perturbation of cancer-associated fibroblast heterogeneity in vitro models

Abstract Cancer-associated fibroblasts (CAFs) are attractive therapeutic targets for cancer due to their abundance in the tumor microenvironment (TME) and extensive pro- and antitumorigenic functions. However, formulating CAF-targeting strategies remains challenging due to the complexity of CAF biology. CAFs specialize into phenotypically and functionally distinct subtypes that may respond differently to specific treatments. Thus, designing CAF-targeting therapies necessitates a thorough understanding of CAF heterogeneity and preclinical model systems that can reliably prototype CAF biology observed in tumors. However, CAF heterogeneity is still not well-understood for many solid tumors, including the stroma-rich pancreatic ductal adenocarcinoma (PDAC), and the translatability of stroma models has not been comprehensively evaluated. In this work, we developed in vitro cell lines of tumor-CAF cocultures using primary CAFs derived from PDAC and used single-cell transcriptomics and CRISPR perturbation to investigate CAF heterogeneity and subtype-specific responses. We found that coculturing primary CAFs with the BxPC3 PDAC cell line could capture the tumor-CAF crosstalks underlying CAF activation. We characterized eight subtypes, including myofibroblastic, inflammatory, extracellular matrix (ECM)-like, and interferon CAFs, which could be preserved with immortalization. We also delineated the trajectories of CAF subtype interconvertibility, highlighting inflammatory CAFs as the likely initial diseased state and ECM CAFs as a “reservoir” that seeded the later states. By correlating the in vitro subtypes with clinical data of immunotherapy responses, we established that the in vitro cell lines could model the immuno-modulatory and immunoresistant phenotypes of CAFs. Finally, using an immortalized tumor-CAF coculture line, we performed Perturb-seq single-cell perturbation to perturb several stroma genes of interest, including TGFBR1, SPATS2L, AEBP1, and PTGS1, and evaluated the subtype-specific effects of the perturbations. We found that perturbing TGFBR1 resulted in the expected eradication of myofibroblastic CAFs, while the other perturbations resulted in subtype-specific modulations of metabolic and extracellular matrix related pathways. Overall, our findings underscored that in vitro tumor-CAF coculture models could serve as a translatable system that effectively captured CAF biology and heterogeneity observed in tumors and highlighted some similarities between PDAC CAFs and previously characterized breast cancer CAFs. We also demonstrated that single-cell perturbation could be a useful approach for interrogating the distinct responses of different CAF subtypes to perturbations. Citation Format: Elysia Saputra, Shamsudheen Karuthedath Vellarikkal, Lixia Li, Hong Sun, Suchitra Natarajan, Federica Piccioni, Alex M. Tamburino, Xin Yu, Aleksandra K. Olow. Characterization and CRISPR perturbation of cancer-associated fibroblast heterogeneity in vitro models [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B009.

The Mechanism by Which Hedgehog Interacting Protein (HHIP) in Cancer-Associated Fibroblasts Regulate the Secretion of Inflammatory Factors Through the JAK1/STAT3 Pathway Affecting Prostate Cancer Stemness.

Prostate cancer (PCa) is seriously affecting men's health and quality of life. Existing studies indicate that PCa stem cells are responsible for promoting the growth and contributing to the high recurrence rate of PCa. We retrieved and downloaded PCa-related datasets from both the GEO and TCGA database. These datasets were subsequently analyzed using single-cell analysis, difference analysis, WGCNA, and machine learning algorithms. WB was performed to detect the expression of Hedgehog interacting protein (HHIP), JAK1/STAT3 pathway-related protein, CD133 and CD44. Immunohistochemistry was conducted to assess the distribution of HHIP and Ki67. The levels of inflammatory factors were measured using ELISA. The tumor cell stemness was evaluated through spheroid formation assay and flow cytometry. Through bioinformatics analysis, we identified eight genes (ARHGAP24, HHIP, MITF, CBX7, PPP1R12B, PLEKHA1, ADGRA2, and PGR). Among these genes, we selected HHIP for follow-up experiments and confirmed its low expression in PCa tumor tissues. Primary cancer-associated fibroblasts (CAFs) were extracted, and to further explore the mechanism of HHIP, we overexpressed or knocked down HHIP in CAFs. Overexpression of HHIP was found to inhibit the JAK1/STAT3 pathway and the secretion of inflammatory factors, thus suppressing both the proliferation and stemness of PCa cells. Treatment of CAFs with the JAK1/STAT3 pathway inhibitor AG490 led to a decrease in inflammatory factor secretion, along with inhibition of PCa cell proliferation and stemness. On this basis, knockdown of HHIP partially reversed the inhibitory effects of AG490 on PCa cells. Finally, we constructed a mouse subcutaneous tumor model and found that HHIP inhibited tumor proliferation and densification. In summary, HHIP in CAFs can regulate the JAK1/STAT3 pathway and affect the secretion of inflammatory factors, thus affecting the proliferation of PCa.

Cancer-associated Fibroblasts (CAFs) Regulate Lung Cancer Malignant Progression by Transferring SERPINE2 (PN1) Via Exosomes.

Cancer-associated fibroblasts (CAFs), one of the most abundant stromal cell types in tumor microenvironment (TME), have been a potential target for cancer treatment such as lung cancer. However, the underlying mechanism by which CAFs promote lung cancer progression remains elusive. We obtained primary CAFs, normal fibroblasts (NFs) and their exosomes, constructed protease nexin-1 (PN1) stably silenced or over-expressed CAFs cells using lentivirus. Bioinformatics was used to obtain the expression of PN1 in lung cancer and normal tissues, the relationship with overall survival, and the enriched pathways. The MTT assays and Transwell assays were performed to detect the proliferation, migration, and invasion abilities of lung cancer cells after treatments. Western blotting, qRT-PCR, immunohistochemistry, and xenograft models were used to illustrate how CAFs functions in lung cancer progression via exosomes. CAFs-derived exosomes, in which PN1 was higher expressed compared with NFs-derived ones, promoted effectively the proliferation, migration, and invasion of lung cancer cells A549 and H1975. Meanwhile, the expression of PN1 expressed higher in lung cancer tissues compared with normal ones, and was negatively associated with the overall survival rate of lung cancer patients. More importantly, over-expressing or silencing PN1 in A549 and H1975 could also promote or inhibit cell proliferation, migration, and invasion correspondingly. Furthermore, treated with PN1 over-expressed CAFs-derived exosomes, the lung cancer cells proliferation, migration, and invasion varied positively, and accompanied by activation of Toll-like and NF-κB signaling pathways. However, this phenomenon can be reversed by AN-3485, an antagonist of Toll-like pathway. Finally, over-expressing PN1 leads to an accelerated tumor growth by increasing the expression of proliferation biomarker Ki67 and activation of NF-κB signaling pathway in vivo. CAFs promoted lung cancer progression by transferring PN1 and activating Toll-like/NF-κB signaling pathway via exosomes.

Abstract A058: Primary cancer-associated fibroblasts alter tumor organoid chemosensitivity through epigenetic regulation

Abstract Pancreatic adenocarcinoma (PDAC) is the 3rd leading cause of cancer-related deaths in Canada with a 5-year survival rate at ∼12%. A major cause of this poor survival rate is the inefficiency of current treatments. Only 20% of patients are eligible for surgical resection while the other 80% are treated with chemotherapies (nab-paclitaxel, Gemcitabine, FOLFIRINOX) having limited efficacy. This resistance is due to the PDAC tumour microenvironment (TME), including cancer-associated fibroblasts (CAFs). Numerous studies show CAFs and the TME affect tumour growth, chemoresistance and metastasis, but the mechanisms underlying the effects are unknown. Epigenetic mechanisms, including DNA methylation and histone modifications, link environmental factors to altered gene expression. Genes encoding epigenetic mediators are often mutated or over-expressed in PDAC, but a role in resistance has yet to be defined. We hypothesize that epigenetic reprogramming occurs in pancreatic cancer cells in response to secreted factors from CAFs leading to increased therapy resistance. Methods: Most work to date on PDAC resistance has been performed with immortalized cell lines and in two dimensions. Therefore, to test our hypothesis, we established patient-derived organoids (PDO) and CAFs obtained from endoscopic ultrasound (EUS). Clinical data was obtained through the DERIVE (Determination of Response to Therapy in Individual Patients) database. To examine the effects of CAFs on PDOs, we obtained conditioned media (CM) from four, early passage CAFs, grown 48 hours in culture. Organoid media was supplemented 1:1 with CAF-CM and six PDOs grown in this media for up to 14 days. PDO growth and the response to gemcitabine, FOLFIRINOX or radiation was monitored using an Incucyte system. To identify changes in the epigenome and how this reflects changes in gene expression, DNA methylation arrays and ATAC-Seq was performed before and after treatment with CAF-CM and aligned to RNA-seq analysis on RNA isolated at the same time point. Results: Exposure of PDOs to CAF-CM resulted in altered phenotypes and molecular profiles of PDOs in a patient-specific fashion. Increased resistance to chemotherapy (Gemcitabine) and radiotherapy was observed in multiple PDOs. Changes in DNA methylation and chromatin accessibility was aligned with transcriptomic data and identified known and novel pathways linked to chemoresistance. Metabolomic and cytokine analysis on CAFs-CM identified differential enrichment of metabolites linked to epigenetic mediators. We are currently determining if these factors secreted by the CAFs promote chemo and radio-resistance. Conclusions: This study shows the importance in integrating TME components when examining novel therapeutic options. In addition, we show (1) CAFs secrete factors that enhance therapeutic resistance in PDOs and (2) these changes likely involve altered epigenetic reprogramming. Future experiments will identify the epigenetic factors that can be targeted to counteract chemoresistance. Citation Format: Emilie Jaune-Pons, Zachary Klassen, Joana Ribeiro Pinto, Maria Nica, Nadeem Hussain, Michael Sey, Ken Leslie, Matthew Cecchini, Crystal Engelage, Danielle Porplycia, Stephen Welch, Brian Yan, Christopher Pin. Primary cancer-associated fibroblasts alter tumor organoid chemosensitivity through epigenetic regulation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A058.

Research on curcumin mediating immunotherapy of colorectal cancer by regulating cancer associated fibroblasts.

The objective was to investigate curcumin's (Cur) function and associated molecular mechanisms in regulating tumor immunity in colon cancer. Primary cancer-associated fibroblasts (CAFs) from mouse CT26 colon cancer tumors were isolated. Validation of primary CAFs using immunofluorescence assay was done. Cell Counting Kit-8 experiments, real-time quantitative PCR (qPCR), and enzyme linked immunosorbent assay experiments were conducted to investigate how curcumin affected the growth and cytokine secretion functions of CAFs. The effect of curcumin on regulating PD-L1 expression on CT26 cells through CAFs in vitro was explored through coculture of CAFs and tumor cells, qPCR, and western blot experiments. A mouse colon cancer cell model was established in Balb/c nude mice to explore the effect of curcumin on colon tumor cells. Changes in the tumor microenvironment were detected by flow cytometry to explore the synergistic effect of curcumin combined with anti-PD-1 monoclonal antibody in the treatment of mouse colon cancer. In vitro, curcumin prevented the growth and TGF-β secretion of CT26 cells. At the same time, curcumin inhibited the secretion of TGF-β by CAFs, thereby downregulating the PD-L1 expression of CT26 cells. In vivo, curcumin combined with anti-PD-1 antibodies can further enhance the inhibitory effect of PD-1 antibodies on tumors and increase the number of tumor-suppressing immune cells in the tumor microenvironment, such as M1 macrophages and CD8 T cells, thus inhibiting tumors. Immune M2 macrophages, regulatory T cells, and other cells were reduced. In conclusion, curcumin reduces the expression of PD-L1 in colon cancer cells and improves the tumor immune microenvironment by inhibiting the proliferation of CAFs and the secretion of TGF-β. Curcumin and anti-PD-1 treatment have synergistic inhibitory effects on colon cancer.

Reprogramming of normal fibroblasts into ovarian cancer-associated fibroblasts via non-vesicular paracrine signaling induces an activated fibroblast phenotype

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 that conditioned media from ovarian cancer lines leads to an increase in the activated state of fibroblasts demonstrated by functional assays and up-regulation of known CAF-related genes and ECM pathways. 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. Critically, the conditioned CAFs resemble a transcriptional signature with involvement of ECM remodeling. The present study provides mechanistic and functional insights about the activation and reprogramming of CAFs in the ovarian tumor microenvironment mediated by non-vesicular paracrine signaling. Moreover, it provides a translational based approach to reprogram normal fibroblasts from both uterine and ovarian origin into CAFs using tumor-derived conditioned media. Using these resources, further development of therapeutics that possess potentiality and specificity towards CAF/ECM-mediated chemoresistance in OC are further warranted.

Efficacy and safety evaluation of cross-reactive Fibroblast activation protein scFv-based CAR-T cells.

Fibroblast activation protein (FAP) overexpression on cancer-associated fibroblasts (CAFs) is associated with poor prognosis and worse clinical outcomes. Selective ablation of pro-tumorgenic FAP+ stromal cells with CAR-T cells may be a new therapeutic strategy. However, the clinical use of FAP-CAR T cells is suggested to proceed with caution for occasional poor efficacy and induction of on-target off-tumor toxicity (OTOT), including lethal osteotoxicity and cachexia. Hence, more investigations and preclinical trials are required to optimize the FAP-CAR T cells and to approve their safety and efficacy. In this study, we designed second-generation CAR T cells targeting FAP with 4-1BB as a co-stimulatory molecule, and tested their cytotoxicity against FAP-positive cells (hFAP-HT1080 cells and a variety of primary CAFs) in vitro and in Cell line-derived xenograft (CDX) and a patient-derived xenograft (PDX) model. Results showed that our FAP-CAR T cells were powerfully potent in killing human and murine FAP-positive tumor cells and CAFs in multiple types of tumors in BALB/c and C57BL/6 mice and in patient-derived xenografts (PDX) model. And they were proved to be biologically safe and exhibit low-level OTOT. Taken together, the human/murine cross-reactive FAP-CAR T cells were powerfully potent in killing human and murine FAP positive tumor cells and CAFs. They were biologically safe and exhibit low-level OTOT, warranting further clinical investigation into our FAP-CAR T cells.

Cancer-associated fibroblasts derived fibronectin extra domain A promotes sorafenib resistance in hepatocellular carcinoma cells by activating SHMT1

Resistance to sorafenib, an effective first-line treatment for advanced hepatocellular carcinoma (HCC), greatly compromised the prognosis of patients. The extracellular matrix is one of the most abundant components of the tumor microenvironment. Beyond acting as a physical barrier, it remains unclear whether cell interactions and signal transduction mediated by the extracellular matrix contribute to sorafenib resistance. With the analysis of primary HCC organoid RNA-seq data combined with in vivo and in vitro experiments validation, we discovered that fibronectin extra domain A (FN-EDA) derived from cancer-associated fibroblasts played a critical role in sorafenib resistance. Mechanistically, FN-EDA stimulates the up-regulation of the key one-carbon metabolism enzyme SHMT1 in HCC cells via the TLR4/NF-κB signaling pathway, thereby countering the oxidative stress induced by sorafenib. Moreover, we reinforced the clinical significance of our discoveries by conducting in vivo assays with an immunodeficiency subcutaneous xenograft tumor model, which was established using primary cancer-associated fibroblasts derived from clinical HCC tissues, and through the analysis of HCC samples obtained from The Cancer Genome Atlas (TCGA) database. Our findings suggest that targeting the FN-EDA/SHMT1 pathway could be a potential strategy to improve sorafenib responsiveness in HCC patients.

Abstract 735: Mitigation of liver toxicity effects of bispecific T cell engagers in immune-competent liver-tumor co-culturing high-throughput platform

Abstract The remarkable clinical therapeutic effects and wide-ranging applications of bispecific T cell engagers (BiTEs) have revolutionized the treatment approaches in the field of oncology. While the advantages of these innovative immunotherapies are undeniable, it is imperative to thoroughly investigate their safety aspects. With increasing use of biologics for treatment of various cancers, the incidence of immune-related adverse events (irAEs) will undoubtedly increase. Therefore, there is a compelling need to develop measures to effectively prevent or manage irARs already on the stage of the development of new clinical candidates. To address this need, we have created a high-throughput, automation friendly, 384-well-format platform in which 3D spheroid models are co-cultured in units interconnected by microfluidic channel. The tissue-tissue interaction was facilitated by a gravity-driven, tubeless flow system. The design allows for the simultaneous evaluation of the anti-tumor efficacy and liver safety of immunotherapeutics. In our system, we employed 3D spheroids comprised of primary human hepatocytes and Kupffer cells to model the liver, ensuring the preservation of their metabolic and inflammatory functions. Additionally, we established a solid tumor model using human cancer cell lines (HCT116-GFP) and primary cancer-associated fibroblasts, effectively mimicking the complex tumor microenvironment We treated 3D spheroid models with runimotamab (HER2xCD3 BiTE), catumaxomab (EPCAMxCD3), nivatrotamab (GD2xCD3) and control bispecific antibodies in the presence of peripheral blood mononuclear cells (PBMCs). Tumor viability and growth was assessed by fluorescence measurements, while liver toxicity and function were monitored by release of liver aminotransferases ALT and microscopy. To mitigate potential liver toxicity, we co-treated spheroid co-cultures with adalimumab (anti-TNF), tocilizumab (anti-IL-6R), raleukin (IL-1R antagonist) (each 100ug/ml), desatanib, dexamethasone or ruxolitinib (each 100nM). The treatment with all bispecific antibodies resulted in a significant decrease of fluorescence and size of tumor spheroids in comparison to control antibody. At the same time increased ALT concentrations were observed after the treatment with BiTEs. The application of small molecular drugs protected against liver damage, but also severely disrupted tumor killing. Interestingly, adalimumab revealed liver protective actions without affecting tumor killing, suggesting TNF-mediated mechanism of toxicity. In summary, we have developed a relevant, high-throughput platform for the evaluation of novel immunotherapies closely reflecting clinical scenarios. High throughput of the assay represents a powerful screening tool for clinical candidate development. Citation Format: Michal Rudnik, Lisa Hölting, Tamara Häfeli, Özlem Yavaş Grining, Frauke Greve, Daniela Ortiz Franyuti, Ramona Matheis, Laure-Anne Ligeon, Ekaterina Breous-Nystrom, Olivier Frey. Mitigation of liver toxicity effects of bispecific T cell engagers in immune-competent liver-tumor co-culturing high-throughput platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 735.

Abstract 6803: TRIM16 regulates IL-6 secretion in head and neck cancer-associated fibroblasts

Abstract Despite current therapy, head and neck squamous cell carcinoma (HNSCC), the 7th most common cancer worldwide, is associated with high morbidity and mortality. Response to current therapies could be improved with a better understanding of the tumor microenvironment of HNSCC. We previously reported that cancer-associated fibroblasts (CAFs), the most abundant stromal cell type in the HNSCC microenvironment, have elevated levels of basal autophagy than oral fibroblasts from cancer-free subjects (NF). Disrupting autophagy in CAFs with Beclin-1 siRNA reduced secretion of IL-6, IL-8, and other factors known to promote HNSCC progression. The recent emerging role of autophagy in secretion of tumor promoting factors has high impact because (i) the mechanism can provide a new target to block the secretion of protumor factors from CAFs that contribute to HNSCC progression, and (ii) these cytokines can serve as potential indicators for the efficacy of autophagy-targeted therapies. To this end, we carried out an unbiased assessment of the proteins associated with autophagosomes in primary CAFs from HNSCC samples using mass spectrometry. We performed immunoprecipitation of LC3B from the isolated small vesicles of the CAFs, identified and validated the association of several trafficking proteins in secretory autophagy including VAMP3 and SNAP23. Further, the tripartite motif (TRIM) proteins have been shown to mediate the fate of autophagosomes either for degradation or secretion. We hypothesized that TRIM proteins are involved in transport of secretory autophagosomes. Our data demonstrate CAFs express higher levels of TRIM16 mRNA than NF. We demonstrate immunogold labeling of TRIM16 or IL-6 localized to the autophagosomes using transmission electron microscopy. Further, using immunofluorescence, we demonstrated the colocalization of TRIM16 and IL-6, as well as IL-6 and LC3B in cytoplasmic puncta. In addition, we used proximity ligation assays to confirm the interaction of TRIM16 and IL-6, as well as IL-6 and LC3B. TRIM16 knockdown using siRNA in CAFs reduced the secretion of IL-6 as measured by ELISA. In conclusion, we demonstrate an important role of TRIM16 in secretory autophagy making it a potential therapeutic target to mitigate CAF-mediated HNSCC growth. Citation Format: Thuc Ly, Bailey Pickard, Avisha Pandey, Noraida Martinez-Rivera, Eduardo Rosa-Molinar, Michael Washburn, Wen-Xing Ding, Sufi Mary Thomas. TRIM16 regulates IL-6 secretion in head and neck cancer-associated fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6803.

Abstract 1224: 3D models of chemotherapy- and PARPi-resistant ovarian cancer indicate essential roles for JAK/STAT signaling in mediating drug resistance

Abstract Ovarian cancer is the deadliest gynecological cancer with a low 5-year overall survival rate that affects over 300,000 women globally each year. Given lack of routine screening procedures, ovarian cancer patients are frequently diagnosed with late-stage disease that rapidly progress despite initial responses to front line therapy. PARPi and VEGFi targeted therapies have improved progression free survival in small subsets of patients but have largely failed to improve overall survival. Since the robust uptake of PARPis in the front line setting, resistance to this class of drugs is a growing problem. The literature is filled with many novel treatment approaches, but the vast majority fail to gain traction in pre-clinical models and early phase trials. A contributing factor to these disappointments relates to the prevalent use of 2D monoculture model systems that do not recapitulate the tumor microenvironment. To address this issue, we utilized the Rastrum 3D cell printer to grow ovarian cancer cells and PDX models in bio-functional matrices which provide optimal stiffness and extracellular matrix components specific to the ovarian tumor microenvironment. We found that ovarian cancer cells grown under these conditions exhibit dramatic up-regulation of the JAK/STAT signaling pathway, including autocrine/paracrine signaling factors, which correlated with increased sensitivity to JAK/STAT inhibitors. This affect was lost when STAT1 and STAT3 knockout cell lines were grown in this 3D environment. Ovarian tumors are known to be rich in cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). We incorporated primary CAFs into this 3D culture system and found they could promote ovarian cancer cell growth only in cancer cells with intact JAK/STAT signaling further indicating the essential role of this pathway in mediating tumor progression. Co-culture with M2 macrophages was also found to induce ovarian cancer cell growth, particularly in resistant models. Conversely, co-culture with M1 macrophages inhibited treatment naïve ovarian cancer cell growth but not resistant cell line growth. Single-cell RNAseq of the complex 3D cultures elucidated profound differences in the cross-talk between these cell types that is dependent on cancer cell sensitivity to standard-of-care agents. Finally, the addition of JAK/STAT inhibitors was found to substantially alter this cross-talk between cell types and inhibit cancer cell viability. These data further implicate the importance of JAK/STAT signaling, specifically in clinically relevant 3D models, in supporting ovarian cancer progression and response to chemotherapy and PARPi treatment. Ongoing studies are aimed at confirming these findings in pre-clinical mouse models and to elucidate the most effective JAK/STAT inhibitors in vivo with the goal of informing the design of future clinical trials. Citation Format: Esther Rodman, Xiyin Wang, Hannah Smith, Xiaonan Hou, Scott Kaufmann, John Weroha, John Hawse. 3D models of chemotherapy- and PARPi-resistant ovarian cancer indicate essential roles for JAK/STAT signaling in mediating drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1224.

A rationally designed nuclei-targeting FAPI 04-based molecular probe with enhanced tumor uptake for PET/CT and fluorescence imaging.

Fibroblast activation protein inhibitor (FAPI) -based probes have been widely studied in the diagnosis of various malignant tumors with positron emission tomography/computed tomography (PET/CT). However, current imaging studies of FAPI-based probes face challenges in rapid clearance rate and potential false-negative results. Furthermore, FAPI has been rarely explored in optical imaging. Considering this, further modifications are imperative to improve the properties of FAPI-based probes to address existing limitations and broaden their application scenarios. In this study, we rationally introduced methylene blue (MB) to FAPIs, thereby imparting nuclei-targeting and fluorescence imaging capabilities to the probes. Furthermore, we evaluated the added value of FAPI-based fluorescence imaging to traditional PET/CT, exploring the potential application of FAPI-based probes in intraoperative fluorescence imaging. A new FAPI-based probe, namely NOTA-FAPI-MB, was designed for both PET/CT and fluorescence imaging by conjugation of MB. The targeting efficacy of the probe was evaluated on fibroblast activation protein (FAP)-transfected cell line and human primary cancer-associated fibroblasts (CAFs). Subsequently, PET/CT and fluorescence imaging were conducted on tumor-bearing mice. The tumor detection and boundary delineation were assessed by fluorescence imaging of tissues from hepatocellular carcinoma (HCC) patients. NOTA-FAPI-MB demonstrated exceptional targeting ability towards FAP-transfected cells and CAFs in comparison to NOTA-FAPI. This benefit arises from the cationic methylene blue (MB) affinity for anionic nucleic acids. PET/CT imaging of tumor-bearing mice revealed significantly higher tumor uptake of [18F]F-NOTA-FAPI-MB (standard uptake value of 2.20 ± 0.31) compared to [18F]F-FDG (standard uptake value of 1.66 ± 0.14). In vivo fluorescence imaging indicated prolonged retention at the tumor site, with retention lasting up to 24h. In addition, the fluorescent probes enabled more precise lesion detection and tumor margin delineation than clinically used indocyanine green (ICG), achieving a 100.0% (6/6) tumor-positive rate for NOTA-FAPI-MB while 33.3% (2/6) for ICG. These findings highlighted the potential of NOTA-FAPI-MB in guiding intraoperative surgical procedures. The NOTA-FAPI-MB was successfully synthesized, in which FAPI and MB simultaneously contributed to the targeting effect. Notably, the nuclear delivery mechanism of the probes improved intracellular retention time and targeting efficacy, broadening the imaging time window for fluorescence imaging. In vivo PET/CT demonstrated favorable performance of NOTA-FAPI-MB compared to [18F]F-FDG. This study highlights the significance of fluorescence imaging as an adjunct technique to PET/CT. Furthermore, the encouraging results obtained from the imaging of human HCC tissues hold promise for the potential application of NOTA-FAPI-MB in intraoperative fluorescent surgery guidance within clinical settings.

Addressing the Mechanical Interaction Between Cancer-Associated Fibroblasts and Cancer Cells by Laser Ablation.

Cells within a tumor interact by generating, transmitting, and sensing mechanical forces. Among all the cells of the tumor microenvironment, cancer-associated fibroblasts (CAFs) are a paradigmatic example of mechanical communication. In different steps of tumor progression, CAFs pull and push on cancer cells, regulating cancer cell migration, invasion, compartmentalization, and signaling. There is thus an increasing need to experimentally address mechanical interactions within a tumor. A common technique to measure these interactions is laser ablation. Cutting a tissue region with a high-power laser triggers a sudden tissue displacement whose direction and magnitude reveal the local mechanical stresses. In this chapter, we provide a detailed protocol to perform laser ablations in vitro and ex vivo. First, we describe how to prepare cocultures of primary CAFs and cancer cells and tumor explants. Then, we explain how to perform laser ablations in these two systems and how to analyze the induced tissue displacements using particle image velocimetry (PIV). Overall, we provide a workflow to perform, analyze, and interpret laser ablations to explore tumor mechanical interactions.

Immunological signatures from irradiated cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAFs) are abundant and influential elements of the tumor microenvironment (TME), giving support to tumor development in multiple ways. Among other mechanisms, CAFs are important regulators of immunological processes occurring in tumors. However, CAF-mediated tumor immunomodulation in the context of radiotherapy remains poorly understood. In this study, we explore effects of radiation on CAF-derived immunoregulatory signals to the TME. Primary CAF cultures were established from freshly collected human NSCLC lung tumors. CAFs were exposed to single-high or fractionated radiation regimens (1x18Gy or 3x6Gy), and the expression of different immunoregulatory cell-associated and secreted signaling molecules was analyzed 48h and 6 days after initiation of treatment. Analyses included quantitative measurements of released damage-associated molecular patterns (DAMPs), interferon (IFN) type I responses, expression of immune regulatory receptors, and secretion of soluble cytokines, chemokines, and growth factors. CAFs are able to survive ablative radiation regimens, however they enter into a stage of premature cell senescence. Our data show that CAFs avoid apoptosis and do not contribute by release of DAMPs or IFN-I secretion to radiation-mediated tumor immunoregulation. Furthermore, the secretion of relevant immunoregulatory cytokines and growth factors including TGF-β, IL-6, IL-10, TNFα, IL-1β, VEGF, CXCL12, and CXCL10 remain comparable between non-irradiated and radiation-induced senescent CAFs. Importantly, radiation exposure modifies the cell surface expression of some key immunoregulatory receptors, including upregulation of CD73 and CD276. Our data suggest that CAFs do not participate in the release of danger signals or IFN-I secretion following radiotherapy. The immune phenotype of CAFs and radiation-induced senescent CAFs is similar, however, the observed elevation of some cell surface immunological receptors on irradiated CAFs could contribute to the establishment of an enhanced immunosuppressive TME after radiotherapy.

Shikonin reverses cancer-associated fibroblast-induced gemcitabine resistance in pancreatic cancer cells by suppressing monocarboxylate transporter 4-mediated reverse Warburg effect

BackgroundGemcitabine is a first-line chemotherapeutic agent for pancreatic cancer (PC); however, most patients who receive adjuvant gemcitabine rapidly develop resistance and recurrence. Cancer-associated fibroblasts (CAFs) are a crucial component of the tumor stroma that contribute to gemcitabine-resistance. There is thus an urgent need to find a novel therapeutic strategy to improve the efficacy of gemcitabine in PC cells under CAF-stimulation. PurposeTo investigate if shikonin potentiates the therapeutic effects of gemcitabine in PC cells with CAF-induced drug resistance. MethodsPC cell-stimulated fibroblasts or primary CAFs derived from PC tissue were co-cultured with PC cells to evaluate the ability of shikonin to improve the chemotherapeutic effects of gemcitabine in vitro and in vivo. Glucose uptake assay, ATP content analysis, lactate measurement, real-time PCR, immunofluorescence staining, western blot, and plasmid transfection were used to investigate the underlying mechanism. ResultsCAFs were innately resistant to gemcitabine, but shikonin suppressed the PC cell-induced transactivation and proliferation of CAFs, reversed CAF-induced resistance, and restored the therapeutic efficacy of gemcitabine in the co-culture system. In addition, CAFs underwent a reverse Warburg effect when co-cultured with PC cells, represented by enhanced aerobic glycolytic metabolism, while shikonin reduced aerobic glycolysis in CAFs by reducing their glucose uptake, ATP concentration, lactate production and secretion, and glycolytic protein expression. Regarding the mechanism underlying these sensitizing effects, shikonin suppressed monocarboxylate transporter 4 (MCT4) expression and cellular membrane translocation to inhibit aerobic glycolysis in CAFs. Overexpression of MCT4 accordingly reversed the inhibitory effects of shikonin on PC cell-induced transactivation and aerobic glycolysis in CAFs, and reduced its sensitizing effects. Furthermore, shikonin promoted the effects of gemcitabine in reducing the growth of tumors derived from PC cells and CAF co-inoculation in BALB/C mice, with no significant systemic toxicity. ConclusionThese results indicate that shikonin reduced MCT4 expression and activation, resulting in inhibition of aerobic glycolysis in CAFs and overcoming CAF-induced gemcitabine resistance in PC. Shikonin is a promising chemosensitizing phytochemical agent when used in combination with gemcitabine for PC treatment. The results suggest that disrupting the metabolic coupling between cancer cells and stromal cells might provide an attractive strategy for improving gemcitabine efficacy.

MYL9 expressed in cancer-associated fibroblasts regulate the immune microenvironment of colorectal cancer and promotes tumor progression in an autocrine manner

BackgroundThe tumor microenvironment (TME) is an important factor that regulates the progression of colorectal cancer (CRC). Cancer-associated fibroblasts (CAFs) are the main mesenchymal cells in the TME and play a vital role in tumor progression; however, the specific underlying mechanisms require further study.MethodsMultiple single-cell and transcriptome data were analyzed and validated. Primary CAFs isolation, CCK8 assay, co-culture assay, western blotting, multiple immunofluorescence, qRT-PCR, ELISA, immunoprecipitation, ChIP, double luciferase, and animal experiments were used to explore the potential mechanism of MYL9 regulation in CRC.ResultsOur findings revealed that MYL9 was predominantly localized and expressed in CAFs rather than in CRC cells, and bioinformatics analysis revealed that high MYL9 expression was strongly associated with poor overall and disease-free survival in various tumors. In addition, high MYL9 expression is closely associated with M2 macrophage infiltration, which can lead to an immunosuppressive microenvironment in CRC, making it insensitive to immunotherapy. Mechanically, MYL9 can regulate the secretion of CAFs on CCL2 and TGF-β1, thus affecting the immune microenvironment and progression of CRC. In addition, MYL9 bounded with IQGAP1 to regulate CCL2 and TGF-β1 secretion through the ERK 1/2 pathway, and CCL2 and TGF-β1 synergistically promoted CRC cells progression through the PI3K-AKT pathway. Furthermore, MYL9 promotes epithelial-mesenchymal transition (EMT) in CRC. During the upstream regulation of MYL9 in CAFs, we found that the EMT transcription factor ZEB1 could bind to the MYL9 promoter in CAFs, enhancing the activity and function of MYL9. Therefore, MYL9 is predominantly expressed in CAFs and can indirectly influence tumor biology and EMT by affecting CAFs protein expression in CRC.ConclusionsMYL9 regulates the secretion of cytokines and chemokines in CAFs, which can affect the immune microenvironment of CRC and promote CRC progression. The relationship between MYL9 expression and CRC clinical staging and immunotherapy is closer in CAFs than in tumor cells; therefore, studies using CAFs as a model deserve more attention when exploring tumor molecular targets in clinical research.

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

ObjectiveGastric 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.MethodsWe 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.ResultsThe 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.ConclusionOur 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.

HS6ST1 overexpressed in cancer-associated fibroblast and inhibited cholangiocarcinoma progression.

Fibroblasts turn into cancer associated fibroblasts (CAFs) in the tumor microenvironment, which play an important role in tumor progression. However, the mechanism is unclear. To investigate the role of CAFs with HS6ST1-overexpression in cell migration and invasion effects. Human primary CAFs were isolated and identified from intrahepatic cholangiocarcinoma. mRNA profiles differences between CAFs and NFs were examined by using transcriptome sequencing. Using Transwell® migration assays, ICCA cells (RBE and HUCCT1) with NF-CM, CAF-CM, CAFsNC-CM, and CAFsHS6ST1-CM were analyzed. Immunohistochemical staining were used to analyze the expression of HS6ST1 in CAF in 152 patients with ICCA. Overall survival (OS) was compared based on CAF HS6ST1 expression were analysed. The relationship between clinicopathological parameters and survival was also examined. Successfully isolated CAFs is positive staining with αSMA, FSP-1, FAP, and PDGFR-β. Transcriptome sequencing showed that differently expressed genes were enriched in the function of the extracellular matrix and chemokine signaling pathway. HS6ST1 is differentially expressed between CAFs and NFs, and associated with the migration and invasion of ICCA cells. Moreover, HS6ST1 positive expression of CAFs predicted unfavorable prognosis in patients with intrahepatic cholangiocarcinoma and showed correlation with the presence of lymph node metastasis. HS6ST1 is new possibilities for targeting the CAFs to reduce cholangiocarcinoma growth and metastasis.

Cancer-associated fibroblasts promote venous thrombosis through podoplanin/CLEC-2 interaction in podoplanin-negative lung cancer mouse model

BackgroundCancer-associated thrombosis (CAT) is the leading cause of morbidity and mortality. Cancer-associated fibroblasts (CAFs) are a prominent component of the tumor microenvironment that contributes to cancer progression through direct cell–cell interactions and the release of extracellular vesicles (EVs). However, the role of CAFs in CAT remains unclear. ObjectiveThis study aims to investigate whether CAFs aggravate CAT and the underlying molecular mechanism using a preclinical mouse lung cancer model. MethodsWe designed a Lewis lung carcinoma (LLC) tumor-bearing mouse model. CAFs were characterized using fluorescence immunohistostaining. The presence of podoplanin, a platelet-activating membrane protein through C-type lectin-like receptor 2 (CLEC-2), in EVs isolated from primary CAFs or LLC tumor tissues was assessed by immunoblotting. The platelet activation and aggregation abilities of the EVs were quantified using flow cytometry. Podoplanin plasma levels were measured by enzyme-linked immunosorbent assay. Venous thrombosis was induced in the femoral vein using 2.5% ferric chloride. The anti-CLEC-2 monoclonal antibody 2A2B10 was used to deplete CLEC-2 on the surface of the platelets. ResultsCAFs expressing CD90, PDGFRβ, HSP47, CD34, and vimentin, co-expressed podoplanin and induced platelet activation and aggregation in a CLEC-2-dependent manner. Tumor-bearing mice showed elevated podoplanin plasma levels. CAF-EV injection and tumor-bearing mice showed shorter occlusion time in the venous thrombosis model. Although tumor growth was not altered, antibody-induced CLEC-2 depletion suppressed venous thrombosis in the tumor-bearing state but not in the healthy condition. ConclusionCAFs and CAF-derived EVs induce CLEC-2-dependent platelet aggregation and aggravate venous thrombosis.

Primary cancer-associated fibroblasts exhibit high heterogeneity among breast cancer subtypes.

Cancer-associated fibroblasts (CAFs) are a diverse subset of cells, that is recently gaining in popularity and have the potential to become a new target for breast cancer (BC) therapy; however, broader research is required to understand their mechanisms and interactions with breast cancer cells. The goal of the study was to isolate CAFs from breast cancer tumour and characterise isolated cell lines. We concentrated on numerous CAF biomarkers that would enable their differentiation. Flow cytometry, immunofluorescence, and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) were used to phenotype the primary CAFs. According to our findings, there was no significant pattern in the classification of cancer-associated fibroblasts. The results of biomarkers expression were heterogeneous, thus no specific subtypes were identified. Furthermore, a comparison of cancer-associated fibroblasts derived from different BC subtypes (luminal A and B, triple-negative, HER2 positive) did not reveal any clear trend of expression.