Cancer-associated Fibroblasts Markers Research Articles

Integration of single-cell RNA-seq and bulk RNA-seq data to construct and validate a cancer-associated fibroblast-related prognostic signature for patients with ovarian cancer

BackgroundTo establish a prognostic risk profile for ovarian cancer (OC) patients based on cancer-associated fibroblasts (CAFs) and gain a comprehensive understanding of their role in OC progression, prognosis, and therapeutic efficacy.MethodsData on OC single-cell RNA sequencing (scRNA-seq) and total RNA-seq were collected from the GEO and TCGA databases. Seurat R program was used to analyze scRNA-seq data and identify CAFs clusters corresponding to CAFs markers. Differential expression analysis was performed on the TCGA dataset to identify prognostic genes. A CAF-associated risk signature was designed using Lasso regression and combined with clinicopathological variables to develop a nomogram. Functional enrichment and the immune landscape were also analyzed.ResultsFive CAFs clusters were identified in OC using scRNA-seq data, and 2 were significantly associated with OC prognosis. Seven genes were selected to develop a CAF-based risk signature, primarily associated with 28 pathways. The signature was a key independent predictor of OC prognosis and relevant in predicting the results of immunotherapy interventions. A novel nomogram combining CAF-based risk and disease stage was developed to predict OC prognosis.ConclusionThe study highlights the importance of CAFs in OC progression and suggests potential for innovative treatment strategies. A CAF-based risk signature provides a highly accurate prediction of the prognosis of OC patients, and the developed nomogram shows promising results in predicting the OC prognosis.

ScRNA-seq characterizing the heterogeneity of fibroblasts in breast cancer reveals a novel subtype SFRP4+ CAF that inhibits migration and predicts prognosis.

Cancer-associated fibroblasts (CAFs) are a diverse group of cells that significantly impact the tumor microenvironment and therapeutic responses in breast cancer (BC). Despite their importance, the comprehensive profile of CAFs in BC remains to be fully elucidated. To address this gap, we utilized single-cell RNA sequencing (scRNA-seq) to delineate the CAF landscape within 14 BC normal-tumor paired samples. We further corroborated our findings by analyzing several public datasets, thereby validating the newly identified CAF subtype. Additionally, we conducted coculture experiments with BC cells to assess the functional implications of this CAF subtype. Our scRNA-seq analysis unveiled eight distinct CAF subtypes across five tumor and six adjacent normal tissue samples. Notably, we discovered a novel subtype, designated as SFRP4+ CAFs, which was predominantly observed in normal tissues. The presence of SFRP4+ CAFs was substantiated by two independent scRNA-seq datasets and a spatial transcriptomics dataset. Functionally, SFRP4+ CAFs were found to impede BC cell migration and the epithelial-mesenchymal transition (EMT) process by secreting SFRP4, thereby modulating the WNT signaling pathway. Furthermore, we established that elevated expression levels of SFRP4+ CAF markers correlate with improved survival outcomes in BC patients, yet paradoxically, they predict a diminished response to neoadjuvant chemotherapy in cases of triple-negative breast cancer. This investigation sheds light on the heterogeneity of CAFs in BC and introduces a novel SFRP4+ CAF subtype that hinders BC cell migration. This discovery holds promise as a potential biomarker for refined prognostic assessment and therapeutic intervention in BC.

Progressive changes in the protein expression profile of alveolar septa in early-stage lung adenocarcinoma.

Adenocarcinomas show a stepwise progression from atypical adenomatous hyperplasia (AAH) through adenocarcinoma in situ (AIS) to invasive adenocarcinoma (IA). Immunoglobulin superfamily containing leucine-rich repeat (ISLR) is a marker of tumor-restraining cancer-associated fibroblasts (CAFs), which are distinct from conventional, strongly α-smooth muscle actin (αSMA)-positive CAFs. Fibroblastactivation protein (FAP) has been focused on as a potential therapeutic and diagnostic target of CAFs. We investigated the changes in protein expression during adenocarcinoma progression in the pre-existing alveolar septa by assessing ISLR, αSMA, and FAP expression in normallung, AAH, AIS, and IA. Fourteen AAH, seventeen AIS, and twenty IA lesions were identified and randomly sampled. Immunohistochemical analysis was performed to evaluate cancer-associated changes and FAP expression in the pre-existing alveolar structures. Normal alveolar septa expressed ISLR. The ISLR level in the alveolar septa decreased in AAH and AIS tissues when compared with that in normal lung tissue. The αSMA-positive area gradually increased from the adjacent lung tissue (13.3% ± 15%) to AIS (87.7% ± 14%), through AAH (70.2% ± 21%). Moreover, the FAP-positive area gradually increased from AAH (1.69% ± 1.4%) to IA (11.8% ± 7.1%), through AIS (6.11% ± 5.3%). Protein expression changes are a feature of CAFs in the pre-existing alveolar septa that begin in AAH. These changes gradually progressed from AAH to IA through AIS. FAP-positive fibroblasts may contribute to tumor stroma formation in early-stage lung adenocarcinoma, and this could influence the development of therapeutic strategies targeting FAP-positive CAFs for disrupting extracellular matrix formation.

Heterogeneity and interplay: the multifaceted role of cancer-associated fibroblasts in the tumor and therapeutic strategies.

The journey of cancer development is a multifaceted and staged process. The array of treatments available for cancer varies significantly, dictated by the disease's type and stage. Cancer-associated fibroblasts (CAFs), prevalent across various cancer types and stages, play a pivotal role in tumor genesis, progression, metastasis, and drug resistance. The strategy of concurrently targeting cancer cells and CAFs holds great promise in cancer therapy. In this review, we focus intently on CAFs, delving into their critical role in cancer's progression. We begin by exploring the origins, classification, and surface markers of CAFs. Following this, we emphasize the key cytokines and signaling pathways involved in the interplay between cancer cells and CAFs and their influence on the tumor immune microenvironment. Additionally, we examine current therapeutic approaches targeting CAFs. This article underscores the multifarious roles of CAFs within the tumor microenvironment and their potential applications in cancer treatment, highlighting their importance as key targets in overcoming drug resistance and enhancing the efficacy of tumor therapies.

Regulatory role of Echinochrome A in cancer-associated fibroblast-mediated lung cancer cell migration.

Echinochrome A (Ech A), a marine biosubstance isolated from sea urchins, is a strong antioxidant, and its clinical form, histochrome, is being used to treat several diseases, such as ophthalmic, cardiovascular, and metabolic diseases. Cancer-associated fibroblasts (CAFs) are a component of the tumor stroma and induce phenotypes related to tumor malignancy, including epithelial-mesenchymal transition (EMT) and cancer stemness, through reciprocal interactions with cancer cells. Here, we investigated whether Ech A modulates the properties of CAFs and alleviates CAF-induced lung cancer cell migration. First, we observed that the expression levels of CAF markers, Vimentin and fibroblast-activating protein (FAP), were decreased in Ech A-treated CAF-like MRC5 cells. The mRNA transcriptome analysis revealed that in MRC5 cells, the expression of genes associated with cell migration was largely modulated after Ech A treatment. In particular, the expression and secretion of cytokine and chemokine, such as IL6 and CCL2, stimulating cancer cell metastasis was reduced through the inactivation of STAT3 and Akt in MRC5 cells treated with Ech A compared to untreated MRC5 cells. Moreover, while conditioned medium from MRC5 cells enhanced the migration of non-small cell lung cancer cells, conditioned medium from MRC5 cells treated with Ech A suppressed cancer cell migration. In conclusion, we suggest that Ech A might be a potent adjuvant that increases the efficacy of cancer treatments to mitigate lung cancer progression.

CAF-associated genes putatively representing distinct prognosis by in silico landscape of stromal components of colon cancer.

Comprehensive understanding prognostic relevance of distinct tumor microenvironment (TME) remained elusive in colon cancer. In this study, we performed in silico analysis of the stromal components of primary colon cancer, with a focus on the markers of cancer-associated fibroblasts (CAF) and tumor-associated endothelia (TAE), as well as immunological infiltrates like tumor-associated myeloid cells (TAMC) and cytotoxic T lymphocytes (CTL). The relevant CAF-associated genes (CAFG)(representing R index = 0.9 or beyond with SPARC) were selected based on stroma specificity (cancer stroma/epithelia, cS/E = 10 or beyond) and expression amounts, which were largely exhibited negative prognostic impacts. CAFG were partially shared with TAE-associated genes (TAEG)(PLAT, ANXA1, and PTRF) and TAMC-associated genes (TAMCG)(NNMT), but not with CTL-associated genes (CTLG). Intriguingly, CAFG were prognostically subclassified in order of fibrosis (representing COL5A2, COL5A1, and COL12A1) followed by exclusive TAEG and TAMCG. Prognosis was independently stratified by CD8A, a CTL marker, in the context of low expression of the strongest negative prognostic CAFG, COL8A1. CTLG were comprehensively identified as IFNG, B2M, and TLR4, in the group of low S/E, representing good prognosis. Our current in silico analysis of the micro-dissected stromal gene signatures with prognostic relevance clarified comprehensive understanding of clinical features of the TME and provides deep insights of the landscape.

Integration of Single-Cell and Bulk RNA-seq Data to Identify the Cancer-Associated Fibroblast Subtypes and Risk Model in Glioma.

Cancer-associated fibroblasts (CAFs) are an important component of the stroma. Studies showed that CAFs were pivotally in glioma progression which have long been considered a promising therapeutic target. Therefore, the identification of prognostic CAF markers might facilitate the development of novel diagnostic and therapeutic approaches. A total of 1333 glioma samples were obtained from the TCGA and CGGA datasets. The EPIC, MCP-counter, and xCell algorithms were used to evaluate the relative proportion of CAFs in glioma. CAF markers were identified by the single-cell RNA-seq datasets (GSE141383) from the Tumor Immune Single-Cell Hub database. Unsupervised consensus clustering was used to divide the glioma patients into different distinct subgroups. The least absolute shrinkage and selection operator regression model was utilized to establish a CAF-related signature (CRS). Finally, the prognostic CAF markers were further validated in clinical specimens by RT‒qPCR. Combined single-cell RNA-seq analysis and differential expression analysis of samples with high and low proportions of CAFs revealed 23 prognostic CAF markers. By using unsupervised consensus clustering, glioma patients were divided into two distinct subtypes. Subsequently, based on 18 differentially expressed prognostic CAF markers between the two CAF subtypes, we developed and validated a new CRS model (including PCOLCE, TIMP1, and CLIC1). The nomogram and calibration curves indicated that the CRS was an accurate prognostic marker for glioma. In addition, patients in the high-CRS score group had higher immune infiltration and tumor mutation burden levels. Moreover, the CRS score had the potential to predict the response to immune checkpoint blockade (ICB) therapy and chemotherapy. Finally, the expression profiles of three CAF markers were verified by RT‒qPCR. In general, our study classified glioma patients into distinct subgroups based on CAF markers, which will facilitate the development of individualized therapy. We also provided insights into the role of the CRS in predicting the response to ICB and chemotherapy in glioma patients.

Abstract 4167: Selective imaging of cancer-associated fibroblasts in the breast cancer microenvironment with near-infrared fluorescent probes

Abstract Tumors consist of a complex mixture of resident and infiltrating cells that can support their survival and evasion of treatment. Selective detection of genetically stable cells in the tumor microenvironment (TME) offers insight into tumor biology beyond the malignant cells, which are the focus of most molecular imaging approaches to cancer detection. Motivated by the goal of non-invasively understanding the primary breast TME, we have developed fluorescent molecular probes that target cancer-associated fibroblasts (CAFs), a major component of the stromal compartment of many tumors, and emit light in the near-infrared (NIR) spectral window, providing access to deeper tissues than visible probes. We synthesized and characterized a series of CAF-targeted antibody- and small molecule-based fluorescent imaging agents utilizing a highly hydrophilic NIR dye and ligands that target Fibroblast Activation Protein (FAP). FAP is a key cell-surface marker of breast cancer CAFs with an S1 phenotype, which are modulators of immunosuppression, metastatic spread, and are associated with worse outcomes, especially in HER2+ and triple-negative breast cancer. Modifications to the chemical structure of the linker and targeting ligands allowed us to alter the specificity and brightness of the CAF-probes in cellulo. Imaging of a co-implanted tumor model of SKBR3 human breast cancer cells and FAP expressing fibroblasts after administering our lead small-molecule CAF imaging agent revealed selective tumor targeting of CAF-rich tumors compared to cancer cell predominant tumors with favorable pharmacokinetics and tumor-to-background ratio (TBR) greater than 2. Similar imaging studies with MMTV-PyMT transgenic mice, an established murine model of breast cancer, showed analogous enhanced uptake in mammary tumors (TBR > 2) and clearance over 24 hours. NIR fluorescence also correlated with CAFs isolated from PyMT tumor tissue via flow cytometry, consistent with our hypothesis that this agent can specifically detect endogenous CAFs. This study identified a novel, bright, and water-soluble FAP-specific NIR agent for in vivo imaging, setting the stage for simultaneous optical imaging of malignant cells and activated fibroblasts in the TME to elucidate cancer-host interactions. Citation Format: Megan S. Michie, Junwei Du, Jiayu (Jennifer) Ye, Kathleen Duncan, Mikhail Y. Berezin, Samuel Achilefu. Selective imaging of cancer-associated fibroblasts in the breast cancer microenvironment with near-infrared fluorescent probes [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 4167.

Abstract 4342: Breast cancer multi-omic single cell profiling identifies key progressive disease markers

Abstract Breast cancer is one of the most diagnosed cancers and has a complex tumor microenvironment (TME). Breast tumors are subtyped by receptor expression, and all have a high degree of cellular heterogeneity. We analyzed tumors from 8 individuals with early-stage breast cancer. The patients had either triple negative breast (TNBC) or an estrogen receptor (ER) positive cancer. The tumors and normal adjacent tissue were profiled by single-nuclei gene expression (GEX) and ATAC data using the 10X multi-ome methodology. Gene set analysis identified specific epithelial clusters associated with the estrogen early/late response, epithelial mesenchymal transition, and several key cytokine pathways. From those epithelial cells, a subset highly proliferative in nature emerged. It consists of both ER positive and TNBC tumor types enriched for specific DNA transcriptional motifs including those for stem cell (Yamanaka) factors and other cellular proliferation motifs. GEX proliferation markers such as MKi-67 were also highly expressed. Overlaying GEX and ATAC data, it was possible to filter the numerous differentially expressed genes and peaks into a subset of genes specific to progressive breast cancer within the proliferative cluster. Those genes included ESRP1, POP4, CCNE1, and AAMDC all of which are associated with progressive breast cancer. To further elucidate the complexity of the TME, we examined clusters of fibroblasts from our dataset. A difference in cancer associated fibroblast marker gene expression was related to the level of ER expression expressed in the tumor epithelium. In general, ER-low tumor fibroblasts had higher expression of immune cancer associated fibroblasts (iCAFs) markers while ER-positive and TNBC tumors had greater expression of extracellular matrix associated markers (emCAFs). Specific clusters were enriched for emCAFs and iCAFs representing another critical part of the TME. In conclusion, using a multi-modal single-cell approach to the TME allowed the identification of an aggressive cluster of epithelial cells marked by genes for cellular proliferation and noted therapeutic targets while also characterizing other critical TME components especially, CAFs. Citation Format: Hugh Russell, Manisha Rao, Grant Duclos, Rogelio Aguilar, Nick Barkas, Megan Callahan, Ojasvi Chaudhary, Peter Gathungu, Chris Rands, Varsha Shankarappa, Daniel Stetson, Asaf Rotem, Maurizio Scaltriti, Brian Dougherty. Breast cancer multi-omic single cell profiling identifies key progressive disease markers [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 4342.

Influential upregulation of KCNE4: Propelling cancer associated fibroblasts-driven colorectal cancer progression

BackgroundColorectal cancer (CRC) is a malignancy of remarkable heterogeneity and heightened morbidity. Cancer associated fibroblasts (CAFs) are abundant in CRC tissues and are essential for CRC growth. Here, we aimed to develop a CAF-related classifier for predicting the prognosis of CRC and identify critical pro-tumorigenic genes in CAFs.MethodThe mRNA expression and clinical information of CRC samples were sourced from two comprehensive databases, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Using a weighted gene co-expression network analysis (WGCNA) approach, CAF-related genes were identified and a CAF risk signature was developed through the application of univariate analysis and the least absolute shrinkage and selection operator (LASSO) Cox regression model. EdU cell proliferation assay, and transwell assay were performed to detect the oncogenic role of KCNE4 in CAFs.ResultsWe constructed a prognostic CAF model consisting of two genes (SFRP2 and KCNE4). CRC patients were classified into low- and high-CAF-risk groups using the median CAF risk score, and patients in the high-CAF-risk group had worse prognosis. Meanwhile, a higher risk score for CAFs was associated with greater stromal and CAF infiltrations, as well as higher expression of CAF markers. Furthermore, TIDE analysis indicated that patients with a high CAF risk score are less responsive to immunotherapy. Our further experiments had confirmed the strong correlation between KCNE4 and the malignant phenotypes of CAFs. Moreover, we had shown that KCNE4 could actively promote tumor-promoting phenotypes in CAFs, indicating its critical role in cancer progression.ConclusionThe two-gene prognostic CAF signature was constructed and could be reliable for predicting prognosis for CRC patients. Moreover, KCNE4 may be a promising strategy for the development of novel anti-cancer therapeutics specifically directed against CAFs.

Digital spatial proteomic profiling reveals immune checkpoints as biomarkers in lymphoid aggregates and tumor microenvironment of desmoplastic melanoma

BackgroundDesmoplastic melanoma (DM) is a rare melanoma subtype characterized by dense fibrous stroma, a propensity for local recurrence, and a high response rate to programmed cell death protein 1 (PD-1)...

Uterine leiomyosarcoma cell-derived extracellular vesicles induce the formation of cancer-associated fibroblasts

ObjectiveUterine leiomyosarcoma (ULMS) is a rare malignant tumor, which is aggressive, and has a poor prognosis even during its early stages. Extracellular vesicles (EVs) carry cargo, such as microRNAs (miRNAs), which are involved in intercellular communication in the tumor microenvironment and other processes. Because there are no studies on EV-related miRNAs in ULMS, we identified EV-related miRNAs in ULMS and examined their function. MethodsSmall EVs (sEVs) and medium/large EVs (m/lEVs) were extracted from ULMS cells by ultracentrifugation and their basic characteristics were evaluated. Then, small RNA sequencing was done to obtain EV-related miRNA profiles. Next, miRNA expression levels in sera and tissues of ULMS patients were compared with those of myoma patients. ResultsmiR-654-3p and miR-369-3p were indicated to be highly expressed in both sera and tissues of ULMS patients. These two miRNAs are also highly expressed in ULMS cell lines and ULMS-derived EVs. Some cancer-associated fibroblast (CAF) markers were increased when fibroblasts were treated with ULMS-derived EVs. Furthermore, fibroblasts took up EVs derived from ULMS as determined by confocal laser microscopy. In addition, the transfection of the two candidate miRNAs into fibroblasts significantly increased some CAF markers, particularly ACTA2. ConclusionmiR-654-3p and miR-369-3p are highly expressed in ULMS-derived EVs, indicating that these EV-related miRNAs induce the formation of cancer-associated fibroblasts.

Development, preclinical evaluation and preliminary dosimetry profiling of SB03178, a first-of-its-kind benzo[h]quinoline-based fibroblast activation protein-α-targeted radiotheranostic for cancer imaging and therapy

Fibroblast activation protein-α (FAP) is a marker of cancer-associated fibroblasts (CAFs) that constitute a significant portion of most carcinomas. Since it plays a critical role in tumor growth and metastasis, its timely detection to identify tumor lesions in early developmental stages using targeted radiopharmaceuticals has gained significant impetus. In the present work, two novel FAP-targeted precursors SB03178 and SB04033 comprising of an atypical benzo[h]quinoline construct were synthesized and either chelated to diagnostic radionuclide gallium-68 or therapeutic radionuclide lutetium-177, with ≥90% radiochemical purities and 22–76% decay-corrected radiochemical yields. natGa-labeled complexes displayed dose-dependent FAP inhibition, with binding potency of natGa-SB03178 being ∼17 times higher than natGa-SB04033. To evaluate their pharmacokinetic profiles, PET imaging and ex vivo biodistribution analyses were executed in FAP-overexpressing HEK293T:hFAP tumor-bearing mice. While both tracers displayed clear tumor visualization that was primarily FAP-arbitrated, with negligible uptake in most peripheral tissues, [68Ga]Ga-SB03178 demonstrated higher tumor uptake and superior tumor-to-background contrast ratios than [68Ga]Ga-SB04033. 177Lu-labeled SB03178 was subjected to tumor retention studies, mouse dosimetry profiling and mouse-to-human dose extrapolations also using the HEK293T:hFAP tumor model. [177Lu]Lu-SB03178 exhibited a combination of high and sustained tumor uptake, with excellent tumor-to-critical organ uptake ratios resulting in a high radiation absorbed dose to the tumor and a low estimated whole-body dose to humans. Our preliminary findings are considerably encouraging to support clinical development of [68Ga]Ga-/[177Lu]Lu-SB03178 theranostic pair for use in a vast majority of FAP-overexpressing neoplasms, particularly carcinomas.

Dynamic phenotypic reprogramming and chemoresistance induced by lung fibroblasts in small cell lung cancer.

Small cell lung cancer (SCLC) is heterogenous in phenotype and microenvironment. Dynamic phenotypic reprogramming, leading to heterogeneity, is prevalent in SCLC, while the mechanisms remain incompletely understood. Cancer-associated fibroblasts (CAFs) possess comprehensive roles in cancer progression, while their function in phenotypic reprogramming of SCLC remain elusive. Here, we obtained transcriptome data of SCLC tissues from publicly available databases, subsequently estimated abundance of CAFs. We found CAF-abundant SCLC exhibited non-neuroendocrine (Non-NE) characteristics. Supporting this, the positive correlation of expression level of α-SMA, the CAF marker, and expression level of REST, protein typically expressed in Non-NE type SCLC, was identified in SCLC tissue arrays. Moreover, we revealed that fibroblasts inhibited NE markers expression and cell proliferation of SCLC cells in the co-culture system comprising lung fibroblasts and SCLC cells, indicating a phenotypic reprogramming from NE to Non-NE. During this process, fibroblast-derived IL-6 activated the JAK2/STAT3 signaling, upregulated c-MYC expression, and subsequently activated the NOTCH pathway, driving phenotypic reprogramming. Moreover, CAF-enriched SCLC exhibited increased immune cell infiltration, elevated expression of immune activation-related signatures, and checkpoint molecules. Our data also highlighted the chemoresistance induced by fibroblasts in SCLC cells, which was effectively reversed by JAK inhibitor. In conclusion, fibroblasts induced phenotypic reprogramming of SCLC cells from NE to Non-NE, likely contributes to inflamed immune microenvironment and chemoresistance. These findings provide novel insights into the clinical implications of CAFs in SCLC.

Periostin in Cancer-Associated Fibroblasts Promotes Esophageal Squamous Cell Carcinoma Progression by Enhancing Cancer and Stromal Cell Migration

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment are involved in the progression of various cancers, including esophageal squamous cell carcinoma (ESCC). CAF-like cells were generated through direct co-culture of human bone marrow-derived mesenchymal stem cells, one of CAF origins, with ESCC cells. Periostin (POSTN) was found to be highly expressed in CAF-like cells. After direct co-culture, ESCC cells showed increased malignant phenotypes, such as survival, growth, and migration, as well as increased phosphorylation of Akt and extracellular signal-regulated kinase (Erk). Recombinant human POSTN activated Akt and Erk signaling pathways in ESCC cells, enhancing survival and migration. The suppression of POSTN in CAF-like cells by siRNA during direct co-culture also suppressed enhanced survival and migration in ESCC cells. In ESCC cells, knockdown of POSTN receptor integrin β4 inhibited Akt and Erk phosphorylation, and survival and migration increased by POSTN. POSTN also enhanced mesenchymal stem cell and macrophage migration and endowed macrophages with tumor-associated macrophage-like properties. Immunohistochemistry showed that high POSTN expression in the cancer stroma was significantly associated with tumor invasion depth, lymphatic and blood vessel invasion, higher pathologic stage, CAF marker expression, and infiltrating tumor-associated macrophage numbers. Moreover, patients with ESCC with high POSTN expression exhibited poor postoperative outcomes. Thus, CAF-secreted POSTN contributed to tumor microenvironment development. These results indicate that POSTN may be a novel therapeutic target for ESCC.

Cancer-associated fibroblasts (CAFs) based model reveals potential for predicting bladder cancer patients’ prognoses and immunotherapy responses

Aim: The purpose of this study is to enhance the understanding of bladder cancer and the role of cancer-associated fibroblasts (CAFs) in its progression. We aim to identify CAF-specific biomarkers and develop a prognostic prediction model based on CAFs, thereby contributing to the advancement of treatment strategies and the identification of prognostic and predictive biomarkers for bladder cancer. Method: We employed single-cell RNA sequencing to detect biomarkers for CAFs in bladder cancer cells. Bladder cancer cohorts were categorized into low- and high-CAF groups using the ssGSEA algorithm. The study also explored the association between CAF-related scores, immune-related cells, and immune checkpoint-related genes. Furthermore, we performed GSVA analysis to understand the biological features of CAFs and their link to various cancer-related pathways. Result: Ten genes were identified as CAF markers in bladder cancer cells. A significant difference was found with 2712 differentially expressed genes between low-CAF and high-CAF tissues. The CAFs-based prognostic prediction model included nine genes (ALDH1L2, AL450384.2, EMP1, LINC02362, WFIKKN1, GOLGA8A, POU5F1, AL354919.2, PTPRR), which are potentially crucial in predicting bladder cancer prognosis. The GSVA analysis revealed the involvement of several cancer-related pathways, such as WNT, toll-like receptor, TGF-beta, MAPK, and MTOR signaling pathways, in the CAFs-based prognostic model. Conclusion: This study highlights the significant role of CAFs in the progression and prognosis of bladder cancer. The identified CAF biomarkers and the constructed prognostic model provide valuable insights for future research and potential therapeutic targets. CAF-dependent pathways are promising for the development of new treatments and improving the prognosis of bladder cancer patients.

Cellular origin and molecular mechanisms of lung metastases in patients with aggressive hepatoblastoma.

Lung metastases are the most threatening signs for patients with aggressive hepatoblastoma (HBL). Despite intensive studies, the cellular origin and molecular mechanisms of lung metastases in patients with aggressive HBL are not known. The aims of these studies were to identify metastasis-initiating cells in primary liver tumors and to determine if these cells are secreted in the blood, reach the lung, and form lung metastases. We have examined mechanisms of activation of key oncogenes in primary liver tumors and lung metastases and the role of these mechanisms in the appearance of metastasis-initiating cells in patients with aggressive HBL by RNA-Seq, immunostaining, chromatin immunoprecipitation, Real-Time Quantitative Reverse Transcription PCR and western blot approaches. Using a protocol that mimics the exit of metastasis-initiating cells from tumors, we generated 16 cell lines from liver tumors and 2 lines from lung metastases of patients with HBL. We found that primary HBL liver tumors have a dramatic elevation of neuron-like cells and cancer-associated fibroblasts and that these cells are released into the bloodstream of patients with HBL and found in lung metastases. In the primary liver tumors, the ph-S675-β-catenin pathway activates the expression of markers of cancer-associated fibroblasts; while the ZBTB3-SRCAP pathway activates the expression of markers of neurons via cancer-enhancing genomic regions/aggressive liver cancer domains leading to a dramatic increase of cancer-associated fibroblasts and neuron-like cells. Studies of generated metastasis-initiating cells showed that these cells proliferate rapidly, engage in intense cell-cell interactions, and form tumor clusters. The inhibition of β-catenin in HBL/lung metastases-released cells suppresses the formation of tumor clusters. The inhibition of the β-catenin-cancer-enhancing genomic regions/aggressive liver cancer domains axis could be considered as a therapeutic approach to treat/prevent lung metastases in patients with HBL.

Co-expression patterns of cancer associated fibroblast markers reveal distinct subgroups related to patient survival in oropharyngeal squamous cell carcinoma.

Background: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) is rapidly increasing in high income countries due to its association with persistent high-risk human papilloma virus (HPV) infection. Recent scientific advances have highlighted the importance of the tumor microenvironment in OPSCC. In this study, including 216 OPSCC patients, we analyze the composition of four established markers of cancer associated fibroblasts (CAFs) in the context of intratumoral CD8 T-cell infiltration. Methods: Immunohistochemical staining for fibroblast activation protein (FAP), platelet-derived growth factor receptor beta (PDGFRb), periostin, alpha smooth muscle actin (α-SMA) and CD8 were analyzed digitally and their association with survival, tumor- and patient characteristics was assessed. Results: Co-expression of CAF markers was frequent but not associated with HPV status. FAPhigh and PDGFRbhigh expression were associated with increased CD8 T-cell infiltration. Low expression of PDGFRb improved patient survival in female patients but not in male patients. We identified PDGFRblow periostinlow α-SMAlow status as an independent predictor of improved survival (hazard ratio 0.377, p = 0.006). Conclusion: These findings elucidate the co-expression of four established CAF markers in OPSCC and underscore their association with T-cell infiltration and patient survival. Future analyses of CAF subgroups in OPSCC may enable the development of individualized therapies.

Abstract B028: Fibroblast PIN1 regulates growth factor and metabolic crosstalk to impact a subset of pancreatic cancer cells

Abstract Pancreatic cancer associated fibroblasts (CAFs) play multiple, often conflicting, roles to support or restrict tumor growth. Recent work suggests that heterogeneous differentiation states of fibroblasts contribute to these diverse functions and that reprogramming of fibroblast states can influence tumor outcomes. How distinct fibroblast subpopulations affect heterogeneous tumor development and growth, however, remains incompletely understood. PIN1 is a phosphorylation-directed prolyl isomerase that alters the conformation and, therefore, the function of many proteins. While PIN1 is known to be overexpressed in cancer and to contribute to cancer cell-intrinsic pro-tumorigenic behaviors, the direct effects of PIN1 inhibition on tumor-associated stromal phenotypes are poorly understood. We have identified a role for PIN1 in regulating fibroblast state and function. Loss or inhibition of PIN1 alters the epigenetic response to TGF-beta, resulting in lower expression of alpha-SMA, a marker of myofibroblast-like CAFs. PIN1 low pancreatic stellate cells (PSCs) or CAFs display decreased proliferation, decreased ECM deposition, and altered paracrine signaling to cancer cells and other stromal cells. In particular, HGF expression was markedly decreased in PIN1 low fibroblasts. Conditioned media from control PSCs was found to activate the MET receptor on cancer cells, driving changes consistent with an epithelial to mesenchymal transition, while conditioned media from shPIN1 PSCs failed to drive these changes. In vivo loss or inhibition of PIN1 significantly decreased tumor growth in multiple mouse models, and consistent with our in vitro data, the smaller lesions in the autochthonous PIN1 knockout KPC mice also displayed decreased expression of alpha-SMA and decreased activation of pMET. To determine the impact of stromal PIN1 on tumor growth, we orthotopically injected KPC pancreatic tumor cell lines into syngeneic PIN1 wildtype or knockout hosts. We found that growth of some cell lines (e.g. KPC8060) were significantly reduced in PIN1 knockout compared to wildtype hosts, while growth of other cells (e.g. KPC7107) were similar in PIN1 wildtype and knockout hosts. In vitro, we found that the KPC8060 cell line increased proliferation and lactate production in response to exogenous HGF, while the KPC7107 cell line did not. This work supports a model in which a subset of pancreatic tumors depends on crosstalk from PIN1 expressing fibroblasts in the tumor microenvironment. We are currently using 2D co-cultures, heterotypic 3D bioprinted tissues, and in vivo mouse models to further understand how PIN1 loss in fibroblasts influences the full tumor microenvironment and to further characterize the dependency of heterogenous pancreatic cancer cells on specific components from a PIN1 sufficient microenvironment. Citation Format: Chloe L. Bowman, Eric J. Carlson, Vidhi Shah, Colin J. Daniel, Xiaoyan Wang, Motoyuki Tsuda, Rosalie C. Sears, Ellen M. Langer. Fibroblast PIN1 regulates growth factor and metabolic crosstalk to impact a subset of pancreatic cancer cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B028.

Abstract A042: Cancer associated fibroblasts drive transcriptional changes in tumor cells from classical to basal phenotype and promote epithelial-to-mesenchymal transition in human pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a heterogeneous tumor comprised of epithelial tumor, endothelial, immune, and importantly, cancer associated fibroblasts (CAFs) cells. CAFs drive a complex tumor microenvironment (TME) through mechanisms of intratumoral interactions that are incompletely understood. It’s crucial to account for the complex role of CAFs in modern ex-vivo tumor systems as regulators of both promoting and restraining tumor growth, providing growth factor support, reprogramming immune cells, and altering the TME. Using our patient-derived organoid (PDO) and CAF coculture, we identify novel intercellular interactions between CAF and PDO that promote tumor cell proliferation, impair response to therapy, and alter transcriptional phenotype. Methods: We interrogate mechanisms of cellular crosstalk in the PDAC TME using a novel three-dimensional, patient-matched coculture of PDO and CAFs, established from patients undergoing surgical resection. Molecular characterization included bulk RNA sequencing-based transcriptomics, comprehensive proteome profiling for 107 secreted proteins with curated validation by ELISA, cellular phenotyping by multiparameter flow cytometry, and qPCR for validation of curated gene lists. Results: Bulk RNAseq of FACS sorted CAF – PDO cocultures from 12 patients demonstrate Moffitt classification transcriptional changes in 42% of samples compared to PDO monoculture, suggesting CAFs drive basal tumor phenotype. To investigate protein level changes, we compared the secreted proteome of PDOs that transitioned to a basal phenotype after coculture to PDOs that did not undergo transition. Proteome analysis from coculture supernatant revealed that HGF, GDF15, TFF3, and VEGF-A are significantly increased in samples that undergo classical to basal transition. Pathway analysis comparing transcriptional data from classical and basal PDOs identifies significant upregulation of pathways associated with epithelial-to-mesenchymal transition (EMT), inflammation, and NF-kB in basal PDOs. Further, coculture leads to decreased expression of E-cadherin and increased expression of N-cadherin on the surface of PDOs while CAF markers remain unchanged. This interaction is accompanied by an increase in PDO proliferation in coculture, suggesting that CAF presence enhances tumorgenicity and changes epithelial tumor cell fitness. Ongoing experiments will investigate tumor cell-CAF interactions spatially using matched patient tissue to complement the in vitro coculture system. Conclusions: Interactions between cancer cells and CAFs drive overall tumor biology via a complex TME and contribute to poor PDAC patient outcomes. Using our patient matched PDO - CAF coculture, we demonstrate that a CAF competent TME drives PDO plasticity towards a more basal transcriptional phenotype and enhanced EMT. We introduce an elegant approach combining in vitro coculture experiments and high dimensional assays to investigate the complex biology of the TME and inform the mechanisms driving cancer biology in individual patients with PDAC. Citation Format: Samantha Guinn, Joseph Tandurella, Jae W. Lee, Daniel J. Zabransky, Mili Ramani, Jignasha Patel, Elana J. Fertig, Elizabeth M. Jaffee, Richard A. Burkhart, Jacquelyn W. Zimmerman. Cancer associated fibroblasts drive transcriptional changes in tumor cells from classical to basal phenotype and promote epithelial-to-mesenchymal transition in human pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A042.