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.

Emilin2 fosters vascular stability by promoting pericyte recruitment.

Angiogenesis, the formation of the new blood vessels from pre-existing vasculature, is an essential process occurring under both normal and pathological conditions, such as inflammation and cancer. This complex process is regulated by several cytokines, growth factors and extracellular matrix components modulating endothelial cell and pericyte function. In this study, we discovered that the extracellular matrix glycoprotein Elastin Microfibril Interfacer 2 (Emilin2) plays a prominent role in pericyte physiology. This work was originally prompted by the observations that tumor-associated vessels from Emilin2-/- mice display less pericyte coverage, impaired vascular perfusion, and reduced drug efficacy, suggesting that Emilin2 could promote vessel maturation and stabilization affecting pericyte recruitment. We found that Emilin2 affects different mechanisms engaged in pericyte recruitment and vascular stabilization. First, human primary endothelial cells challenged with recombinant Emilin2 synthesized and released ∼ 2.1 and 1.2 folds more PDGF-BB and HB-EGF, two cytokines known to promote pericyte recruitment. We also discovered that Emilin2, by directly engaging α5ß1 and α6ß1 integrins, highly expressed in pericytes, served as an adhesion substrate and haptotactic stimulus for pericytes. Moreover, Emilin2 evoked increased NCadherin expression via the sphingosine-1-phosphate receptor, leading to enhanced vascular stability by fostering interconnection between endothelial cells and pericytes. Finally, restoring pericyte coverage in melanoma and ovarian tumor vessels developed in Emilin2-/- mice improved drug delivery to the tumors. Collectively, our results implicate Emilin2 as a prominent regulator of pericyte function and suggest that Emilin2 expression could represent a promising maker to predict the clinical outcome of patients with melanoma, ovarian, and potentially other forms of cancer.

Colorectal cancer development is affected by the ECM molecule EMILIN-2 hinging on macrophage polarization via the TLR-4/MyD88 pathway.

BACKGROUND: Colorectal cancer is one of the most frequent and deadly tumors. Among the key regulators of CRC growth and progression, the microenvironment has emerged as a crucial player and as a possible route for the development of new therapeutic opportunities. More specifically, the extracellular matrix acts directly on cancer cells and indirectly affecting the behavior of stromal and inflammatory cells, as well as the bioavailability of growth factors. Among the ECM molecules, EMILIN-2 is frequently down-regulated by methylation in CRC and the purpose of this study was to verify the impact of EMILIN-2 loss in CRC development and its possible value as a prognostic biomarker. METHODS: The AOM/DSS CRC protocol was applied to Emilin-2 null and wild type mice. Tumor development was monitored by endoscopy, the molecular analyses performed by IHC, IF and WB and the immune subpopulations characterized by flow cytometry. Ex vivo cultures of monocyte/macrophages from the murine models were used to verify the molecular pathways. Publicly available datasets were exploited to determine the CRC patients' expression profile; Spearman's correlation analyses and Cox regression were applied to evaluate the association with the inflammatory response; the clinical outcome was predicted by Kaplan-Meier survival curves. Pearson correlation analyses were also applied to a cohort of patients enrolled in our Institute. RESULTS: In preclinical settings, loss of EMILIN-2 associated with an increased number of tumor lesions upon AOM/DSS treatment. In addition, in the early stages of the disease, the Emilin-2 knockout mice displayed a myeloid-derived suppressor cells-rich infiltrate. Instead, in the late stages, lack of EMILIN-2 associated with a decreased number of M1 macrophages, resulting in a higher percentage of the tumor-promoting M2 macrophages. Mechanistically, EMILIN-2 triggered the activation of the Toll-like Receptor 4/MyD88/NF-κB pathway, instrumental for the polarization of macrophages towards the M1 phenotype. Accordingly, dataset and immunofluorescence analyses indicated that low EMILIN-2 expression levels correlated with an increased M2/M1 ratio and with poor CRC patients' prognosis. CONCLUSIONS: These novel results indicate that EMILIN-2 is a key regulator of the tumor-associated inflammatory environment and may represent a promising prognostic biomarker for CRC patients.

Multimerin-2 orchestrates the cross-talk between endothelial cells and pericytes: A mechanism to maintain vascular stability.

Tumor angiogenesis is vital for the growth and development of various solid cancers and as such is a valid and promising therapeutic target. Unfortunately, the use of the currently available anti-angiogenic drugs increases the progression-free survival by only a few months. Conversely, targeting angiogenesis to prompt both vessel reduction and normalization, has been recently viewed as a promising approach to improve therapeutic efficacy. As a double-edged sword, this line of attack may on one side halt tumor growth as a consequence of the reduction of nutrients and oxygen supplied to the tumor cells, and on the other side improve drug delivery and, hence, efficacy. Thus, it is of upmost importance to better characterize the mechanisms regulating vascular stability. In this context, recruitment of pericytes along the blood vessels is crucial to their maturation and stabilization. As the extracellular matrix molecule Multimerin-2 is secreted by endothelial cells and deposited also in juxtaposition between endothelial cells and pericytes, we explored Multimerin-2 role in the cross-talk between the two cell types. We discovered that Multimerin-2 is an adhesion substrate for pericytes. Interestingly, and consistent with the notion that Multimerin-2 is a homeostatic molecule deposited in the later stages of vessel formation, we found that the interaction between endothelial cells and pericytes promoted the expression of Multimerin-2. Furthermore, we found that Multimerin-2 modulated the expression of key cytokines both in endothelial cells and pericytes. Collectively, our findings posit Multimerin-2 as a key molecule in the cross-talk between endothelial cells and pericytes and suggest that the expression of this glycoprotein is required to maintain vascular stability.

The Efficacy of Anti-PD-L1 Treatment in Melanoma Is Associated with the Expression of the ECM Molecule EMILIN2.

The use of immune checkpoint inhibitors has revolutionized the treatment of melanoma patients, leading to remarkable improvements in the cure. However, to ensure a safe and effective treatment, there is the need to develop markers to identify the patients that would most likely respond to the therapies. The microenvironment is gaining attention in this context, since it can regulate both the immunotherapy efficacyand angiogenesis, which is known to be affected by treatment. Here, we investigated the putative role of the ECM molecule EMILIN-2, a tumor suppressive and pro-angiogenic molecule. We verified that the EMILIN2 expression is variable among melanoma patients and is associated with the response to PD-L1 inhibitors. Consistently, in preclinical settings,the absence of EMILIN-2 is associated with higher PD-L1 expression and increased immunotherapy efficacy. We verified that EMILIN-2 modulates PD-L1 expression in melanoma cells through indirect immune-dependent mechanisms. Notably, upon PD-L1 blockage, Emilin2-/- mice displayed improved intra-tumoral vessel normalization and decreased tumor hypoxia. Finally, we provide evidence indicating that the inclusion of EMILIN2 in a number of gene expression signatures improves their predictive potential, a further indication that the analysis of this molecule may be key for the development of new markers to predict immunotherapy efficacy.

ECM Remodeling in Squamous Cell Carcinoma of the Aerodigestive Tract: Pathways for Cancer Dissemination and Emerging Biomarkers.

Squamous cell carcinomas (SCC) include a number of different types of tumors developing in the skin, in hollow organs, as well as the upper aerodigestive tract (UADT) including the head and neck region and the esophagus which will be dealt with in this review. These tumors are often refractory to current therapeutic approaches with poor patient outcome. The most important prognostic determinant of SCC tumors is the presence of distant metastasis, significantly correlating with low patient survival rates. Rapidly emerging evidence indicate that the extracellular matrix (ECM) composition and remodeling profoundly affect SSC metastatic dissemination. In this review, we will summarize the current knowledge on the role of ECM and its remodeling enzymes in affecting the growth and dissemination of UADT SCC. Taken together, these published evidence suggest that a thorough analysis of the ECM composition in the UADT SCC microenvironment may help disclosing the mechanism of resistance to the treatments and help defining possible targets for clinical intervention.

Cow Milk and Intestinal Epithelial Cell-derived Extracellular Vesicles as Systems for Enhancing Oral Drug Delivery.

Ingestion is the preferred way for drug administration. However, many drugs have poor oral bioavailability, warranting the use of injections. Extracellular vesicles (EVs) from cow milk have shown potential utility in improving oral drug bioavailability. However, EVs produced by intestinal epithelial cells have not been investigated for this application. We compared the capacity of cow milk EVs and intestinal epithelial cell-derived counterparts to enhance oral drug bioavailability. EVs were isolated, fluorescently labelled, and loaded with curcumin (CUR) as a model poorly absorbable drug. These were then characterised before testing in an intestinal model (Caco-2). Epithelial cell-derived EVs showed notably higher cell uptake compared to cow milk EVs. Cell uptake was significantly higher in differentiated compared to undifferentiated cells for both types of EVs. While both milk- and cell-derived EVs improved the cell uptake and intestinal permeability of CUR (confirming oral drug bioavailability enhancement potential), epithelial cell EVs demonstrated a superior effect.