Stromal remodeling regulates dendritic cell abundance and activity in the tumor microenvironment

Protocol to identify and isolate rare murine tumor-resident dendritic cell populations for low-input transcriptomic profiling

Conventional type 1 dendritic cells (cDC1s) are critical for innate sensing of cancer, yet they are scarce in the tumor microenvironment (TME). Here, we present a protocol to identify and isolate cDC1 subsets from murine implantable tumors for subsequent transcriptomic profiling using a flow sorting-based strategy. We describe steps for cell culture of mouse tumors, tumoral growth, dissociation and isolation of tumoral cells, extracellular staining, and cell sorting. We then detail procedures for RNA isolation, mRNA library preparation, and sequencing. For complete details on the use and execution of this protocol, please refer to Papadas et al.1.

Remodeling of tumor microenvironment by extracellular matrix protein 1a differentially regulates ovarian cancer metastasis

We previously reported that extracellular matrix protein 1 isoform a (ECM1a) promotes epithelial ovarian cancer (EOC) through autocrine signaling by binding to cell surface receptors αXβ2. However, the role of ECM1a as a secretory molecule in the tumor microenvironment is rarely reported. In this study, we constructed murine Ecm1-knockout mice and human ECM1a-knockin mice and further generated orthotopic or peritoneal xenograft tumor models to mimic the different metastatic stages of EOC. We show that ECM1a induces oncogenic metastasis of orthotopic xenograft tumors, but inhibits early-metastasis of peritoneal xenograft tumors. ECM1a remodels extracellular matrices (ECM) and promotes remote metastases by recruiting and transforming bone marrow mesenchymal stem cells (BMSCs) into platelet-derived growth factor receptor beta (PDGFRβ+) cancer-associated fibroblasts (CAFs) and facilitating the secretion of angiopoietin-like protein 2 (ANGPTL2). Competing with ECM1a, ANGPTL2 also binds to integrin αX through the P1/P2 peptides, resulting in negative effects on BMSC differentiation. Collectively, this study reveals the dual functions of ECM1a in remodeling of TME during tumor progression, emphasizing the complexity of EOC phenotypic heterogeneity and metastasis.

Targets in the Tumour Matrisome to Promote Cancer Therapy Response

The extracellular matrix (ECM) is composed of complex fibrillar proteins, proteoglycans, and macromolecules, generated by stromal, immune, and cancer cells. The components and organisation of the matrix evolves as tumours progress to invasive disease and metastasis. In many solid tumours, dense fibrotic ECM has been hypothesised to impede therapy response by limiting drug and immune cell access. Interventions to target individual components of the ECM, collectively termed the matrisome, have, however, revealed complex tumour-suppressor, tumour-promoter, and immune-modulatory functions, which have complicated clinical translation. The degree to which distinct components of the matrisome can dictate tumour phenotypes and response to therapy is the subject of intense study. A primary aim is to identify therapeutic opportunities within the matrisome, which might support a better response to existing therapies. Many matrix signatures have been developed which can predict prognosis, immune cell content, and immunotherapy responses. In this review, we will examine key components of the matrisome which have been associated with advanced tumours and therapy resistance. We have primarily focussed here on targeting matrisome components, rather than specific cell types, although several examples are described where cells of origin can dramatically affect tumour roles for matrix components. As we unravel the complex biochemical, biophysical, and intracellular transduction mechanisms associated with the ECM, numerous therapeutic opportunities will be identified to modify tumour progression and therapy response.

WNT/β-catenin regulatory roles on PD-(L)1 and immunotherapy responses

Dysregulation of WNT/β-catenin is a hallmark of many cancer types and a key mediator of metastasis in solid tumors. Overactive β-catenin signaling hampers dendritic cell (DC) recruitment, promotes CD8+ T cell exclusion and increases the population of regulatory T cells (Tregs). The activity of WNT/β-catenin also induces the expression of programmed death-ligand 1 (PD-L1) on tumor cells and promotes programmed death-1 (PD-1) upregulation. Increased activity of WNT/β-catenin signaling after anti-PD-1 therapy is indicative of a possible implication of this signaling in bypassing immune checkpoint inhibitor (ICI) therapy. This review is aimed at giving a comprehensive overview of the WNT/β-catenin regulatory roles on PD-1/PD-L1 axis in tumor immune ecosystem, discussing about key mechanistic events contributed to the WNT/β-catenin-mediated bypass of ICI therapy, and representing inhibitors of this signaling as promising combinatory regimen to go with anti-PD-(L)1 in cancer immunotherapy. Ideas presented in this review imply the synergistic efficacy of such combination therapy in rendering durable anti-tumor immunity.

ADAMTS Proteases: Their Multifaceted Role in the Regulation of Cancer Metastasis

Cancer leads to nearly 10 million deaths worldwide per year. The tumour microenvironment (TME) is fundamental for tumour growth and progression. A key component of the TME, the extracellular matrix (ECM) has recently become a focus of interest in cancer research. Dysregulation of ECM synthesis and proteolysis leads to uncontrolled tumour growth and metastasis. Matrix remodelling enzymes, secreted by cancer cells and stromal cells, modify the overall structure and organisation of ECM proteins, therefore influencing biochemical interactions, tissue integrity and tissue turnover. While A Disintegrin and Metalloproteinases (ADAMs)' and matrix metalloproteinases' role in cancer has been deeply investigated, other proteolytic enzymes, like ADAMs with thrombospondin(-like) motifs (ADAMTSs) have been gaining interest due to their roles in modulating cancer cell-ECM interactions and oncogenic signalling pathways. In this review, we will discuss the dysregulation of ADAMTSs in cancer and their roles in regulating cancer development and progression, via ECM remodelling and cell signalling modulation.

Emerging roles for tumor stroma in antigen presentation and anti-cancer immunity

Advances in immunotherapy in the last decade have revolutionized treatment paradigms across multiple cancer diagnoses. However, only a minority of patients derive durable benefit and progress with traditional approaches, such as cancer vaccines, remains unsatisfactory. A key to overcoming these barriers resides with a deeper understanding of tumor antigen presentation and the complex and dynamic heterogeneity of tumor-infiltrating antigen-presenting cells (APCs). Reminiscent of the 'second touch' hypothesis proposed by Klaus Ley for CD4+ T cell differentiation, the acquisition of full effector potential by lymph node- primed CD8+ T cells requires a second round of co-stimulation at the site where the antigen originated, i.e. the tumor bed. The tumor stroma holds a prime role in this process by hosting specialized APC niches, apparently distinct from tertiary lymphoid structures, that support second antigenic touch encounters and CD8+ T cell effector proliferation and differentiation. We propose that APC within second-touch niches become licensed for co-stimulation through stromal-derived instructive signals emulating embryonic or wound-healing provisional matrix remodeling. These immunostimulatory roles of stroma contrast with its widely accepted view as a physical and functional 'immune barrier'. Stromal control of antigen presentation makes evolutionary sense as the host stroma-tumor interface constitutes the prime line of homeostatic 'defense' against the emerging tumor. In this review, we outline how stroma-derived signals and cells regulate tumor antigen presentation and T-cell effector differentiation in the tumor bed. The re-definition of tumor stroma as immune rheostat rather than as inflexible immune barrier harbors significant untapped therapeutic opportunity.

The entanglement of extracellular matrix molecules and immune checkpoint inhibitors in cancer: a systematic review of the literature

Introduction

Immune-checkpoint inhibitors (ICIs) have emerged as a core pillar of cancer therapy as single agents or in combination regimens both in adults and children. Unfortunately, ICIs provide a long-lasting therapeutic effect in only one third of the patients. Thus, the search for predictive biomarkers of responsiveness to ICIs remains an urgent clinical need. The efficacy of ICIs treatments is strongly affected not only by the specific characteristics of cancer cells and the levels of immune checkpoint ligands, but also by other components of the tumor microenvironment, among which the extracellular matrix (ECM) is emerging as key player. With the aim to comprehensively describe the relation between ECM and ICIs' efficacy in cancer patients, the present review systematically evaluated the current literature regarding ECM remodeling in association with immunotherapeutic approaches.

Methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and was registered at the International Prospective Register of Systematic Reviews (PROSPERO, CRD42022351180). PubMed, Web of Science, and Scopus databases were comprehensively searched from inception to January 2023. Titles, abstracts and full text screening was performed to exclude non eligible articles. The risk of bias was assessed using the QUADAS-2 tool.

Results

After employing relevant MeSH and key terms, we identified a total of 5070 studies. Among them, 2540 duplicates, 1521 reviews or commentaries were found and excluded. Following title and abstract screening, the full text was analyzed, and 47 studies meeting the eligibility criteria were retained. The studies included in this systematic review comprehensively recapitulate the latest observations associating changes of the ECM composition following remodeling with the traits of the tumor immune cell infiltration. The present study provides for the first time a broad view of the tight association between ECM molecules and ICIs efficacy in different tumor types, highlighting the importance of ECM-derived proteolytic products as promising liquid biopsy-based biomarkers to predict the efficacy of ICIs.

Conclusion

ECM remodeling has an important impact on the immune traits of different tumor types. Increasing evidence pinpoint at ECM-derived molecules as putative biomarkers to identify the patients that would most likely benefit from ICIs treatments.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022351180, identifier CRD42022351180.

V3: an enigmatic isoform of the proteoglycan versican

V3 is an isoform of the extracellular matrix (ECM) proteoglycan (PG) versican generated through alternative splicing of the versican gene such that the two major exons coding for sequences in the protein core that support chondroitin sulfate (CS) glycosaminoglycan (GAG) chain attachment are excluded. Thus, versican V3 isoform carries no GAGs. A survey of PubMed reveals only 50 publications specifically on V3 versican, so it is a very understudied member of the versican family, partly because to date there are no antibodies that can distinguish V3 from the CS-carrying isoforms of versican, that is, to facilitate functional and mechanistic studies. However, a number of in vitro and in vivo studies have identified the expression of the V3 transcript during different phases of development and in disease, and selective overexpression of V3 has shown dramatic phenotypic effects in "gain and loss of function" studies in experimental models. Thus, we thought it would be useful and instructive to discuss the discovery, characterization, and the putative biological importance of the enigmatic V3 isoform of versican.

TGF-β1 dominates stromal fibroblast-mediated EMT via the FAP/VCAN axis in bladder cancer cells

BACKGROUND

Bladder cancer is one of the most common malignant tumors of the urinary system and is associated with a poor prognosis once invasion and distant metastases occur. Epithelial-mesenchymal transition (EMT) drives metastasis and invasion in bladder cancer. Transforming growth factor β1 (TGF-β1) and stromal fibroblasts, especially cancer-associated fibroblasts (CAFs), are positive regulators of EMT in bladder cancer. However, it remains unclear how TGF-β1 mediates crosstalk between bladder cancer cells and CAFs and how it induces stromal fibroblast-mediated EMT in bladder cancer. We aimed to investigate the mechanism of TGF-β1 regulation of stromal fibroblast-mediated EMT in bladder cancer cells.

METHODS

Primary CAFs with high expression of fibroblast activation protein (FAP) were isolated from bladder cancer tissue samples. Subsequently, different conditioned media were used to stimulate the bladder cancer cell line T24 in a co-culture system. Gene set enrichment analysis, a human cytokine antibody array, and cytological assays were performed to investigate the mechanism of TGF-β1 regulation of stromal fibroblast-mediated EMT in bladder cancer cells.

RESULTS

Among the TGF-β family, TGF-β1 was the most highly expressed factor in bladder cancer tissue and primary stromal fibroblast supernatant. In the tumor microenvironment, TGF-β1 was mainly derived from stromal fibroblasts, especially CAFs. In stimulated bladder cells, stromal fibroblast-derived TGF-β1 promoted bladder cancer cell migration, invasion, and EMT. Furthermore, TGF-β1 promoted the activation of stromal fibroblasts, inducing CAF-like features, by upregulating FAP in primary normal fibroblasts and a normal fibroblast cell line. Stromal fibroblast-mediated EMT was induced in bladder cancer cells by TGF-β1/FAP. Versican (VCAN), a downstream molecule of FAP, plays an essential role in TGF-β1/FAP axis-induced EMT in bladder cancer cells. VCAN may also function through the PI3K/AKT1 signaling pathway.

CONCLUSIONS

TGF-β1 is a critical mediator of crosstalk between stromal fibroblasts and bladder cancer cells. We revealed a new mechanism whereby TGF-β1 dominated stromal fibroblast-mediated EMT of bladder cancer cells via the FAP/VCAN axis and identified potential biomarkers (FAP, VCAN, N-cadherin, and Vimentin) of bladder cancer. These results enhance our understanding of bladder cancer invasion and metastasis and provide potential strategies for diagnosis, treatment, and prognosis.

An antisteatosis response regulated by oleic acid through lipid droplet-mediated ERAD enhancement

Although excessive lipid accumulation is a hallmark of obesity-related pathologies, some lipids are beneficial. Oleic acid (OA), the most abundant monounsaturated fatty acid (FA), promotes health and longevity. Here, we show that OA benefits Caenorhabditis elegans by activating the endoplasmic reticulum (ER)-resident transcription factor SKN-1A (Nrf1/NFE2L1) in a lipid homeostasis response. SKN-1A/Nrf1 is cleared from the ER by the ER-associated degradation (ERAD) machinery and stabilized when proteasome activity is low and canonically maintains proteasome homeostasis. Unexpectedly, OA increases nuclear SKN-1A levels independently of proteasome activity, through lipid droplet-dependent enhancement of ERAD. In turn, SKN-1A reduces steatosis by reshaping the lipid metabolism transcriptome and mediates longevity from OA provided through endogenous accumulation, reduced H3K4 trimethylation, or dietary supplementation. Our findings reveal an unexpected mechanism of FA signal transduction, as well as a lipid homeostasis pathway that provides strategies for opposing steatosis and aging, and may mediate some benefits of the OA-rich Mediterranean diet.

Differential regulation of TNFα and IL-6 expression contributes to immune evasion in prostate cancer

BACKGROUND

The role of the inflammatory milieu in prostate cancer progression is not well understood. Differences in inflammatory signaling between localized and metastatic disease may point to opportunities for early intervention.

METHODS

We modeled PCa disease progression by analyzing RNA-seq of localized vs. metastatic patient samples, followed by CIBERSORTx to assess their immune cell populations. The VHA CDW registry of PCa patients was analyzed for anti-TNF clinical outcomes.

RESULTS

We observed statistically significant opposing patterns of IL-6 and TNFα expression between localized and metastatic disease. IL-6 was robustly expressed in localized disease and downregulated in metastatic disease. The reverse was observed with TNFα expression. Metastatic disease was also characterized by downregulation of adhesion molecule E-selectin, matrix metalloproteinase ADAMTS-4 and a shift to M2 macrophages whereas localized disease demonstrated a preponderance of M1 macrophages. Treatment with anti-TNF agents was associated with earlier stage disease at diagnosis.

CONCLUSIONS

Our data points to clearly different inflammatory contexts between localized and metastatic prostate cancer. Primary localized disease demonstrates local inflammation and adaptive immunity, whereas metastases are characterized by immune cold microenvironments and a shift towards resolution of inflammation and tissue repair. Therapies that interfere with these inflammatory networks may offer opportunities for early intervention in monotherapy or in combination with immunotherapies and anti-angiogenic approaches.