Tumor-stroma Crosstalk Research Articles

Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumorstroma crosstalk in experimental models

Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumorstroma crosstalk in experimental models

OS056 - Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumour-stroma crosstalk in experimental models

OS056 - Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumour-stroma crosstalk in experimental models

Abstract 5368: Role of spatially distinct tumor fibroblast in erlotinib resistance

Abstract Metabolic reprogramming toward the hexosamine biosynthesis pathway (HBP), an understudied glucose pathway leading to O-glycosylation, is associated with poor survival in the lung adenocarcinoma (LUAD). We found that this metabolic switch happens primarily in Cancer-Associated Fibroblasts (CAFs), an “activated” phenotype associated with bad outcomes in cancer. We show that spatially distinct CAFs harvested from the tumor edge (Tumor-Adjacent-Fibroblasts; TAFs) of LUAD specimens vs the tumor core (Tumor Core Fibroblasts; TCFs) successfully protect cancer cells from erlotinib treatment, as measured by proliferation (ki67), migration (podoplanin) and resistance (Multidrug Resistance 1; MDR1) markers. However, while TCFs increase O-GlcNAcylation in cancer cells, a type of dynamic O-glycosylation, TAFs decrease O-GlcNAcylation in a subpopulation of cells. Interestingly, this subpopulation of cancer cells shows an increase of partial EMT features, as well as proliferation. In addition, we find this population of cancer cells to overexpress the MDR1 transporter, known to actively export erlotinib outside the cell. These results were reproduced in a novel in vitro assembloid model using patient-derived organoids and primary fibroblast mixtures that allow us to characterize cancer and spatially distinct stromal cells in response to erlotinib treatment. Overall, our preliminary results show that TAFs from the invasive leading edge of lung tumors decrease O-GlcNAcylation in cancer cells, which promotes erlotinib resistance. In summary, O-GlcNAcylation represents a potential avenue to mitigate resistance induced by tumor-stroma crosstalk and improve cancer treatment. Citation Format: Gina Bouchard, Sylvia K. Plevritis. Role of spatially distinct tumor fibroblast in erlotinib resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5368.

TGF-β1 induced autophagy in cancer associated fibroblasts during hypoxia contributes EMT and glycolysis via MCT4 upregulation

The Transforming growth factor-β1 (TGF- β1) in the tumor microenvironment (TME) is the major cytokine that acts as a mediator of tumor-stroma crosstalk, which in fact has a dual role in either promoting or suppressing tumor development. The cancer-associated fibroblasts (CAFs) are the major cell types in the TME, and the interaction with most of the epithelial cancers is the prime reason for cancer survival. However, the molecular mechanisms, associated with the TGF- β1 induced tumor promotion through tumor-CAF crosstalk are not well understood. In the Reverse Warburg effect, CAFs feed the adjacent cancer cells by lactate produced during the aerobic glycolysis. We hypothesized that the monocarboxylate transporter, MCT4 which is implicated in lactate efflux from the CAFs, must be overexpressed in the CAFs. Contextually, to explore the role of TGF- β1 in the hypoxia-induced autophagy in CAFs, we treated CoCl2 and external TGF- β1 to the human dermal fibroblasts and L929 murine fibroblasts. We demonstrated that hypoxia accelerated the TGF- β1 signaling and subsequent transformation of normal fibroblasts to CAFs. Moreover, we elucidated that synergistic induction of autophagy by hypoxia and TGF- β1 upregulate the aerobic glycolysis and MCT4 expression in CAFs. Furthermore, we showed a positive correlation between glucose consumption and MCT4 expression in the CAFs. Autophagy was also found to be involved in the EMT in hypoxic CAFs. Collectively, these findings reveal the unappreciated role of autophagy in TME, which enhances the CAF transformation and that promotes tumor migration and metastasis via the reverse Warburg effect.

Galectin-1 orchestrates an inflammatory tumor-stroma crosstalk in hepatoma by enhancing TNFR1 protein stability and signaling in carcinoma-associated fibroblasts.

Most cases of hepatocellular carcinoma (HCC) arise with the fibrotic microenvironment where hepatic stellate cells (HSCs) and carcinoma-associated fibroblasts (CAFs) are critical components in HCC progression. Therefore, CAF normalization could be a feasible therapy for HCC. Galectin-1 (Gal-1), a β-galactoside-binding lectin, is critical for HSC activation and liver fibrosis. However, few studies has evaluated the pathological role of Gal-1 in HCC stroma and its role in hepatic CAF is unclear. Here we showed that Gal-1 mainly expressed in HCC stroma, but not cancer cells. High expression of Gal-1 is correlated with CAF markers and poor prognoses of HCC patients. In co-culture systems, targeting Gal-1 in CAFs or HSCs, using small hairpin (sh)RNAs or an therapeutic inhibitor (LLS30), downregulated plasminogen activator inhibitor-2 (PAI-2) production which suppressed cancer stem-like cell properties and invasion ability of HCC in a paracrine manner. The Gal-1-targeting effect was mediated by increased a disintegrin and metalloprotease 17 (ADAM17)-dependent TNF-receptor 1 (TNFR1) shedding/cleavage which inhibited the TNF-α → JNK → c-Jun/ATF2 signaling axis of pro-inflammatory gene transcription. Silencing Gal-1 in CAFs inhibited CAF-augmented HCC progression and reprogrammed the CAF-mediated inflammatory responses in a co-injection xenograft model. Taken together, the findings uncover a crucial role of Gal-1 in CAFs that orchestrates an inflammatory CSC niche supporting HCC progression and demonstrate that targeting Gal-1 could be a potential therapy for fibrosis-related HCC.

Rab13 Sustains Breast Cancer Stem Cells by Supporting Tumor-Stroma Cross-talk.

Targeting Rab13 perturbs formation of the breast cancer stem cell niche by inhibiting cross-talk between cancer cells and the tumor microenvironment, providing a therapeutic opportunity for niche-targeted breast cancer treatment.

Natural Compounds Targeting Cancer-Associated Fibroblasts against Digestive System Tumor Progression: Therapeutic Insights.

Cancer-associated fibroblasts (CAFs) are critical for cancer occurrence and progression in the tumor microenvironment (TME), due to their versatile roles in extracellular matrix remodeling, tumor–stroma crosstalk, immunomodulation, and angiogenesis. CAFs are the most abundant stromal component in the TME and undergo epigenetic modification and abnormal signaling cascade activation, such as transforming growth factor-β (TGF-β) and Wnt pathways that maintain the distinct phenotype of CAFs, which differs from normal fibroblasts. CAFs have been considered therapeutic targets due to their putative oncogenic functions. Current digestive system cancer treatment strategies often result in lower survival outcomes and fail to prevent cancer progression; therefore, comprehensive characterization of the tumor-promoting and -restraining CAF activities might facilitate the design of new therapeutic approaches. In this review, we summarize the enormous literature on natural compounds that mediate the crosstalk of CAFs with digestive system cancer cells, discuss how the biology and the multifaceted functions of CAFs contribute to cancer progression, and finally, pave the way for CAF-related antitumor therapies.

Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumor-stroma crosstalk in experimental models

Cholangiocarcinoma (CCA) comprises a heterogeneous group of malignant tumors associated with dismal prognosis. Alterations in post-translational modifications (PTMs), including NEDDylation, result in abnormal protein dynamics, cell disturbances and disease. Herein, we investigate the role of NEDDylation in CCA development and progression. Levels and functions of NEDDylation, together with response to pevonedistat (NEDDylation inhibitor) or CRISPR/Cas9 against NAE1 were evaluated invitro, invivo and/or in patients with CCA. The development of preneoplastic lesions in Nae1+/- mice was investigated using an oncogene-driven CCA model. The impact of NEDDylation in CCA cells on tumor-stroma crosstalk was assessed using CCA-derived cancer-associated fibroblasts (CAFs). Proteomic analyses were carried out by mass-spectrometry. The NEDDylation machinery was found overexpressed and overactivated in human CCA cells and tumors. Most NEDDylated proteins found upregulated in CCA cells, after NEDD8-immunoprecipitation and further proteomics, participate in the cell cycle, proliferation or survival. Genetic (CRISPR/Cas9-NAE1) and pharmacological (pevonedistat) inhibition of NEDDylation reduced CCA cell proliferation and impeded colony formation invitro. NEDDylation depletion (pevonedistat or Nae1+/- mice) halted tumorigenesis in subcutaneous, orthotopic, and oncogene-driven models of CCA invivo. Moreover, pevonedistat potentiated chemotherapy-induced cell death in CCA cells invitro. Mechanistically, impaired NEDDylation triggered the accumulation of both cullin RING ligase and NEDD8 substrates, inducing DNA damage and cell cycle arrest. Furthermore, impaired NEDDylation in CCA cells reduced the secretion of proteins involved in fibroblast activation, angiogenesis, and oncogenic pathways, ultimately hampering CAF proliferation and migration. Aberrant protein NEDDylation contributes to cholangiocarcinogenesis by promoting cell survival and proliferation. Moreover, NEDDylation impacts the CCA-stroma crosstalk. Inhibition of NEDDylation with pevonedistat may represent a potential therapeutic strategy for patients with CCA. Little is known about the role of post-translational modifications of proteins in cholangiocarcinoma development and progression. Herein, we show that protein NEDDylation is upregulated and hyperactivated in cholangiocarcinoma, promoting tumor growth. Pharmacological inhibition of NEDDylation halts cholangiocarcinogenesis and could be an effective therapeutic strategy to tackle these tumors.

TWIST1 expression is associated with high-risk neuroblastoma and promotes primary and metastatic tumor growth

The embryonic transcription factors TWIST1/2 are frequently overexpressed in cancer, acting as multifunctional oncogenes. Here we investigate their role in neuroblastoma (NB), a heterogeneous childhood malignancy ranging from spontaneous regression to dismal outcomes despite multimodal therapy. We first reveal the association of TWIST1 expression with poor survival and metastasis in primary NB, while TWIST2 correlates with good prognosis. Secondly, suppression of TWIST1 by CRISPR/Cas9 results in a reduction of tumor growth and metastasis colonization in immunocompromised mice. Moreover, TWIST1 knockout tumors display a less aggressive cellular morphology and a reduced disruption of the extracellular matrix (ECM) reticulin network. Additionally, we identify a TWIST1-mediated transcriptional program associated with dismal outcome in NB and involved in the control of pathways mainly linked to the signaling, migration, adhesion, the organization of the ECM, and the tumor cells versus tumor stroma crosstalk. Taken together, our findings confirm TWIST1 as promising therapeutic target in NB.

Molecular sensors for detection of tumor-stroma crosstalk.

In most solid tumors, malignant cells coexist with non-cancerous host tissue comprised of a variety of extracellular matrix components and cell types, notably fibroblasts, immune cells, and endothelial cells. It is becoming increasingly evident that the non-cancerous host tissue, often referred to as the tumor stroma or the tumor microenvironment, wields tremendous influence in the proliferation, survival, and metastatic ability of cancer cells. The tumor stroma has an active biological role in the transmission of signals, such as growth factors and chemokines that activate oncogenic signaling pathways by autocrine and paracrine mechanisms. Moreover, the constituents of the stroma define the mechanical properties and the physical features of solid tumors, which influence cancer progression and response to therapy. Inspired by the emerging importance of tumor-stroma crosstalk and oncogenic physical forces, numerous biosensors, or advanced imaging and analysis techniques have been developed and applied to investigate complex and challenging questions in cancer research. These techniques facilitate measurements and biological readouts at scales ranging from subcellular to tissue-level with unprecedented level of spatial and temporal precision. Here we examine the application of biosensor technology for studying the complex and dynamic multiscale interactions of the tumor-host system.

Macro- and micro-nutrient–based multiplex stress conditions modulate in vitro tumorigenesis and aggressive behavior of breast cancer spheroids

PurposeThe aggressive nature of a tumor is presumably its inherent one, but different environmental cues can manipulate it in many ways. In this context, the influence of metabolic stresses on tumor behavior needs to be analyzed to understand their far-reaching implications on tumor aggression and dormancy. This work investigates different facets of the tumor, such as tumorigenic capacity, tumor phenotype, and migration, under multiple metabolic stress conditions.MethodsNon-invasive and invasive multicellular spheroids (MTS) were created and subjected to multiple stress conditions, namely glucose, amino acid, and oxygen deprivation. Altered behavior of the MTS has been evaluated in the context of in vitro tumorigenesis, spheroid formation capacity, phenotype, mRNA profile, migration, and recruitment of mesenchymal stem cells.ResultsThe metabolic stress conditions were observed to negatively impact the in vitro tumorigenesis and spheroid formation process of invasive and non-invasive breast cancer cells. While the stress seemingly influences the growth and phenotype of spheroids, it does not alter the organization of sub-cellular entities significantly. Metabolic stress conditions impact the transcriptomic landscape of hypoxic, angiogenic, ECM deformation, glycolysis shift, and protein starvation-related gene clusters. MTSs do not adhere or migrate under stress, but they exhibit different modalities of migration when rescued. Invasive spheroids, after the rescue, exhibit increased aggressiveness. Furthermore, stressed spheroid was observed to control the migration and recruitment of mesenchymal stem cells.ConclusionMultiplex metabolic stresses could control the tumorigenesis while influencing the physiology of invasive and non-invasive breast cancer spheroids along with their migration pattern and tumor-stromal crosstalk.

The transformation of cancer-associated fibroblasts: Current perspectives on the role of TGF-β in CAF mediated tumor progression and therapeutic resistance.

Over the last few years, the Transforming growth factor- β (TGF-β) has been significantly considered as an effective and ubiquitous mediator of cell growth. The cytokine, TGF-β is being increasingly recognized as the most potent inducer of cancer cell initiation, differentiation, migration as well as progression through both the SMAD-dependent and independent pathways. There is growing evidence that supports the role of secretory cytokine TGF-β as a crucial mediator of tumor-stroma crosstalk. Contextually, the CAFs are the prominent component of tumor stroma that helps in tumor progression and onset of chemoresistance. The interplay between the CAFs and the tumor cells through the paracrine signals is facilitated by cytokine TGF-β to induce the malignant progression. Here in this review, we have dissected the most recent advancements in understanding the mechanisms of TGF-β induced CAF activation, their multiple origins, and most importantly their role in conferring chemoresistance. Considering the pivotal role of TGF-β in tumor perogression and associated stemness, it is one the proven clinical targets We have also included the clinical trials going on, targeting the TGF-β and CAFs crosstalk with the tumor cells. Ultimately, we have underscored some of the outstanding issues that must be deciphered with utmost importance to unravel the successful strategies of anti-cancer therapies.

Transcriptomic deconvolution reveals unique tumor microenvironmental interactions across intracranial meningioma WHO grades

Meningiomas are common tumors arising in the primary central nervous system. Although recent radiotherapy and surgical procedures have improved clinical outcomes, there remains a need for novel therapeutics to treat meningiomas resisting current approaches. To reveal putative therapeutic targets in meningioma, the present exploratory study inferred stromal and tumor compartment gene expression from bulk meningioma tumor RNA-sequencing data and revealed certain ligand-receptor interactions in tumor microenvironment which may direct future studies. Bulk tumor gene expression developed from 152 primary meningiomas encompassing WHO grades I-III were deconvolved into tumor and stromal compartment expression through non-negative linear regression using tumor purity estimates, ultimately revealing previously unknown features of tumor-stromal crosstalk in meningioma. It was found that fibroblast growth factor receptor 4 (FGFR4) and human epidermal growth factor receptor 4 (HER4) was implicated in multiple tumor-stroma interactions. Specific chemokine receptors, such as CCR4 and CCR7, were frequently involved in stroma-stroma crosstalk. Additionally, genes reflecting immune-exhausted T cell responses also displayed distinct expression across the WHO grades. Taken together, the findings reveal potential therapeutic targets which should be investigated further.

Marker-free lineage tracing reveals an environment-instructed clonogenic hierarchy in pancreatic cancer.

Effective treatments for pancreatic ductal adenocarcinoma (PDAC) are lacking, and targeted agents have demonstrated limited efficacy. It has been speculated that a rare population of cancer stem cells (CSCs) drives growth, therapy resistance, and rapid metastatic progression in PDAC. These CSCs demonstrate high clonogenicity invitro and tumorigenic potential invivo. However, their relevance in established PDAC tissue has not been determined. Here, we use marker-independent stochastic clonal labeling, combined with quantitative modeling of tumor expansion, to uncover PDAC tissue growth dynamics. We find that in contrast to the CSC model, all PDAC cells display clonogenic potential in situ. Furthermore, the proximity to activated cancer-associated fibroblasts determines tumor cell clonogenicity. This means that the microenvironment is dominant in defining the clonogenic activity of PDAC cells. Indeed, manipulating the stroma by Hedgehog pathway inhibition alters the tumor growth mode, revealing that tumor-stroma crosstalk shapes tumor growth dynamics and clonal architecture.

The distinct roles of exosomes in tumor-stroma crosstalk within gastric tumor microenvironment

Gastric cancer (GC) development is a complex process displaying polytropic cell and molecular landscape within gastric tumor microenvironment (TME). Stromal cells in TME, including fibroblasts, endothelial cells, mesenchymal stem cells, and various immune cells, support tumor growth, metastasis, and recurrence, functioning as the soil for gastric tumorigenesis. Importantly, exosomes secreted by either stromal cells or tumor cells during tumor-stroma crosstalk perform as crucial transporter of agents including RNAs and proteins for cell-cell communication in GC pathogenesis. Therefore, given the distinct roles of exosomes secreted by various cell types in GC TME, increasing evidence has indicated that exosomes present as new biomarkers for GC diagnosis and prognosis and shed light on novel approaches for GC treatment.

HGF/MET Axis Induces Tumor Secretion of Tenascin-C and Promotes Stromal Rewiring in Pancreatic Cancer.

Simple SummaryIt has been previously shown that activation of the MET receptor by its ligand, the hepatocyte growth factor (HGF), modulates the tumor-stroma cross-talk in models of pancreatic cancer. We now wish to cast light on the molecular mechanisms by which this ligand/receptor pair sustains the interaction between cancer cells and the tumor microenviroment. To this end, we compared data obtained by large-scale analysis of gene expression in pancreatic cancer cells grown in the presence of HGF versus cells grown in the presence of HGF and treated with specific inhibitors of HGF/MET signaling. By clustering differentially expressed genes according to functional groups, we identified candidate genes involved in the process. Among these, tenascin C was selected due to its activity in sustaining the malignant phenotype. Our results highlight a new role for tenascin C, which could represent the operative arm through which MET promotes activation of the stromal compartment in pancreatic cancer.Pancreatic ductal adenocarcinoma is an aggressive tumor characterized by the presence of an abundant stromal compartment contributing significantly to the malignant phenotype. Pancreatic stellate cells are peculiar fibroblasts present in the stroma and represent the predominant source of extracellular matrix proteins, pro-inflammatory cytokines, and growth factors, including hepatocyte growth factor (HGF). Exploiting a co-culture system of human pancreatic stellate cells and cancer cells, we demonstrated that fibroblast activation was reduced upon HGF/MET axis inhibition. To unveil the signaling pathways sustaining stroma modulation orchestrated by MET activation in the tumor, we analyzed the gene expression profile in pancreatic cancer cells stimulated with HGF and treated with HGF/MET inhibitors. Transcriptome analysis showed that, among all the genes modulated by HGF, a subset of 125 genes was restored to the basal level following treatment with the inhibitors. By examining these genes via ingenuity pathway analysis, tenascin C emerged as a promising candidate linking MET signaling and tumor microenvironment. MET-dependent tenascin C modulation in pancreatic cancer cells was validated at RNA and protein levels both in vitro and in vivo. In conclusion, this work identifies tenascin C as a gene modulated by MET activation, suggesting a role in MET-mediated tumor-stroma interplay occurring during pancreatic tumor progression.

Dynamic Stromal Alterations Influence Tumor-Stroma Crosstalk to Promote Pancreatic Cancer and Treatment Resistance.

Simple SummaryPancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies, with a five-year survival rate of only ~10%. Pancreatic tissue becomes increasingly fibrotic (known as desmoplasia) during cancer development and progression. This extensive, heterogeneous reaction is largely mediated through the actions of stromal cells such as cancer-associated fibroblasts (CAFs). In this review, we will discuss how heterotypical reciprocal tumor-stromal and tumor-immune cell interactions in the pancreatic tumor microenvironment (TME) can both promote and restrain PDAC development and progression, with particular focus on the role of extracellular matrix (ECM) in potentiating tumor cell proliferation, survival, metastasis, and treatment resistance. We also give a snapshot of the current and emerging stromal co-therapies used in combination with chemotherapy or immunotherapy to treat this highly deadly disease.Many cancer studies now recognize that disease initiation, progression, and response to treatment are strongly influenced by the microenvironmental niche. Widespread desmoplasia, or fibrosis, is fundamental to pancreatic cancer development, growth, metastasis, and treatment resistance. This fibrotic landscape is largely regulated by cancer-associated fibroblasts (CAFs), which deposit and remodel extracellular matrix (ECM) in the tumor microenvironment (TME). This review will explore the prognostic and functional value of the stromal compartment in predicting outcomes and clinical prognosis in pancreatic ductal adenocarcinoma (PDAC). We will also discuss the major dynamic stromal alterations that occur in the pancreatic TME during tumor development and progression, and how the stromal ECM can influence cancer cell phenotype, metabolism, and immune response from a biochemical and biomechanical viewpoint. Lastly, we will provide an outlook on the latest clinical advances in the field of anti-fibrotic co-targeting in combination with chemotherapy or immunotherapy in PDAC, providing insight into the current challenges in treating this highly aggressive, fibrotic malignancy.

Abstract 103: Spatially resolved transcriptomics identified distinct tumor-stroma crosstalk networks in long term ovarian cancer survivors

Abstract The tumor microenvironment (TME), composed primarily of fibroblasts, endothelial cells, lymphocytic infiltrates and extracellular matrix proteins, can directly affect cancer cell growth, migration, differentiation as well as immune cell landscapes, thereby presenting a unique aspect of diagnosing and treating cancer. Cancer-associated fibroblasts (CAF) and immune cells are the main orchestrators of the ovarian cancer TME. We hypothesized that spatial transcriptomics (ST), which can provide a rich spatial context to gene expression, will identify crosstalk signaling networks among various cell types in the ovarian TME. Advanced stage high-grade serous ovarian cancer (HGSC) tissue frozen sections from two treatment naïve long-term survivors (LTS, overall survival ≥ 10 years) and two short-term survivors (STS, overall survival ≤ 2 years) were placed onto a ST expression slide pre-spotted with 1000 unique barcoded RNA-capturing probes. The ST slides were then stained with H&E and imaged. Tissue permeabilization and cDNA synthesis were then performed directly on the tissue section. The derived barcoded cDNA libraries from each sample were sequenced using Illumina NextSeq500 flow cells. After RNA-Seq analysis, supervised analysis was then performed by selecting different regions (based on tissue histology) in the tumor, tumor/stroma mixture, stroma close or far away from tumor areas to identify differentially expressed genes between STS and LTS. Stromal cells from different spatial locations had unique differentially expressed genes based on their proximity (11 genes in LTS; 11 genes in STS) or remoteness (18 genes in LTS; 10 genes in STS) to cancer cell compartments. Among the major modulated gene networks, higher levels of antigen-presenting molecules were found in the stroma in close proximity to the tumor cell nest than in stroma located far away in LTS tumor samples but not in the STS samples, suggesting an increased number of activated antigen-presenting cells in LTS tumors. In addition, higher levels of adhesion molecules and angiogenetic factors were found in the stroma in close proximity to the tumor cell nest than in stroma located far away in STS tumor samples but not in LTS samples, suggesting that adhesion molecules and angiogenetic factors produced by stromal cells may facilitate the invasiveness of the tumor cells, which subsequently leads to short term survival in patients with the disease. Our findings demonstrate for the first time that spatially resolved transcriptomics allows the identification of prognostic biomarkers associated with overall survival in HGSC patients. Further studies using deconvoluted ST data to further delineate the specific stromal cell subtypes in close proximity to tumors, and imaging mass cytometry (IMC) or multiplexed immunohistochemistry to validate the protein expression of the potential biomarkers are ongoing. Citation Format: Sammy Ferri-Borgogno, Jianting Sheng, Ying Zhu, Kwong K. Wong, Stephen T. Wong, Samuel C. Mok. Spatially resolved transcriptomics identified distinct tumor-stroma crosstalk networks in long term ovarian cancer survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 103.

Abstract 2414: HMGA1 induces FGF19 to drive tumor progression and recruit cancer associated fibroblasts in pancreatic adenocarcinoma

Abstract Pancreatic ductal adenocarcinomas (PDACs) are highly lethal tumors characterized by a dense desmoplastic stroma comprised of cancer associated fibroblasts (CAFs) and fibrotic scar tissue. While stromal CAFs act as a barrier to therapy and release signals promoting tumor growth and invasion, the stroma restricts tumor growth in mouse models. The High Mobility Group A1 (HMGA1) protein is an oncofetal protein and epigenetic regulator that amplifies signals from the microenvironment to foster stem cell properties within intestinal epithelium. Although HMGA1 is highly expressed in embryonic and adult stem cells, it is silenced postnatally in most differentiated cells. HMGA1 becomes aberrantly re-expressed in diverse tumors where high levels predict adverse clinical outcomes. In PDAC, HMGA1 is detected only in late-stage precursor lesions or invasive tumors, but not in normal pancreas nor in early precursor lesions. Moreover, high HMGA1 nuclear staining associates with poor differentiation status and decreased patient survival. Here, we discovered a novel epigenetic program whereby HMGA1 recruits stromal CAFs and drives tumor progression by inducing FGF19. Silencing HMGA1 in PDAC cell lines slows proliferation, disrupts oncogenic properties in vitro (migration, invasion, clonogenicity, 3D sphere formation), and depletes tumor initiator cells in xenograft assays. RNA sequencing revealed transcriptional networks up-regulated by HMGA1 that function in cell signaling and proliferation; we focused on FGF19 as a potential mediator of tumor-stromal crosstalk. HMGA1 binds directly to the FGF19 promoter and recruits active histone marks (H3K4me2, H3K27Aac) to induce gene expression and protein secretion from PDAC cells. Silencing FGF19 recapitulates effects of HMGA1 silencing, disrupting oncogenic and cancer stem cell properties in vitro while depleting tumor initiator cells in vivo. In co-culture experiments, FGF19 is required for CAF migration across a membrane towards PDAC cells. Silencing HMGA1, FGF19, or treatment with FGF19 inhibitors disrupts CAF recruitment. Silencing HMGA1 or FGF19 in PDAC cells also decreases both the desmoplastic stroma and tumor growth in mouse xenografts. In primary tumors, co-expression of HMGA1 and FGF19 predict decreased survival. Together, our results reveal a novel paradigm whereby tumor cells collaborate with CAFs via HMGA1 and FGF19 to drive progression, thus illuminating FGF19 as a rational therapeutic target for PDACs overexpressing HMGA1 and FGF19. Citation Format: Lionel Chia, Shuai Shuai, Jung-Hyun Kim, Woo Jung Sung, Ruitao Zhang, Tait Huso, Leslie Cope, Karen Reddy, Linda M. Resar. HMGA1 induces FGF19 to drive tumor progression and recruit cancer associated fibroblasts in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2414.

Castration-Induced Downregulation of SPARC in Stromal Cells Drives Neuroendocrine Differentiation of Prostate Cancer.

Fatal neuroendocrine differentiation (NED) of castration-resistant prostate cancer is a recurrent mechanism of resistance to androgen deprivation therapies (ADT) and antiandrogen receptor pathway inhibitors (ARPI) in patients. The design of effective therapies for neuroendocrine prostate cancer (NEPC) is complicated by limited knowledge of the molecular mechanisms governing NED. The paucity of acquired genomic alterations and the deregulation of epigenetic and transcription factors suggest a potential contribution from the microenvironment. In this context, whether ADT/ARPI induces stromal cells to release NED-promoting molecules and the underlying molecular networks are unestablished. Here, we utilized transgenic and transplantable mouse models and coculture experiments to unveil a novel tumor-stroma cross-talk that is able to induce NED under the pressure of androgen deprivation. Castration induced upregulation of GRP78 in tumor cells, which triggers miR29-b-mediated downregulation of the matricellular protein SPARC in the nearby stroma. SPARC downregulation enabled stromal cells to release IL6, a known inducer of NED. A drug that targets GRP78 blocked NED in castrated mice. A public, human NEPC gene expression dataset showed that Hspa5 (encoding for GRP78) positively correlates with hallmarks of NED. Finally, prostate cancer specimens from patients developing local NED after ADT showed GRP78 upregulation in tumor cells and SPARC downregulation in the stroma. These results point to GRP78 as a potential therapeutic target and to SPARC downregulation in stromal cells as a potential early biomarker of tumors undergoing NED. SIGNIFICANCE: Tumor-stroma cross-talk promotes neuroendocrine differentiation in prostate cancer in response to hormone therapy via a GRP78/SPARC/IL6 axis, providing potential therapeutic targets and biomarkers for neuroendocrine prostate cancer.