Evaluation of Immunoregulatory Biomarkers on Plasma Small Extracellular Vesicles for Disease Progression and Early Therapeutic Response in Head and Neck Cancer

The role of extracellular vesicle immune checkpoints in cancer

Immune checkpoints (ICPs) play a crucial role in regulating the immune response. In the tumor, malignant cells can hijack the immunosuppressive effects of inhibitory ICPs to promote tumor progression. Extracellular vesicles (EVs) are produced by a variety of cells and contain bioactive molecules on their surface or within their lumen. The expression of ICPs has also been detected in EVs. In vitro and in vivo studies have shown that extracellular vesicle immune checkpoints (EV ICPs) have immunomodulatory effects and are involved in tumor immunity. EV ICPs isolated from the peripheral blood of cancer patients are closely associated with the tumor progression and the prognosis of cancer patients. Blocking inhibitory ICPs has been recognized as an effective strategy in cancer treatment. However, the efficacy of immune checkpoint inhibitors (ICIs) in cancer treatment is hindered by the emergence of therapeutic resistance, which limits their widespread use. Researchers have demonstrated that EV ICPs are correlated with clinical response to ICIs therapy and were involved in therapeutic resistance. Therefore, it is essential to investigate the immunomodulatory effects, underlying mechanisms, and clinical significance of EV ICPs in cancer. This review aims to comprehensively explore these aspects. We have provided a comprehensive description of the cellular origins, immunomodulatory effects, and clinical significance of EV ICPs in cancer, based on relevant studies.

Optimization of extracellular vesicles preparation from saliva of head and neck cancer patients

Small extracellular vesicles from saliva (SEVs) have high potential as biomarkers in Head and Neck cancer (HNC). However, there is no common consensus on the ideal method for their isolation. This study compared different ultracentrifugation (UC) methods (durations and + /- additional purification) with size exclusion chromatography (SEC) and investigated the potential of SEVs as diagnostic biomarkers and their biological activity on NK and CD8+ T cells. SEVs from 19 HNC patients and 8 healthy donors (HDs) were thoroughly characterized. Transmission electron microscopy confirmed the isolation of vesicles by all methods. The average size determined via nanoparticle-tracking analysis was smaller for SEVs isolated by SEC than UC. The highest particle-to-protein yield was achieved by UC (3 h + 3 h) (UCopt) and SEC. However, SEC yielded considerably fewer SEVs. Comparing the surface marker cargo, SEVs isolated by UCopt from HNC patients carried more PD-L1, FasL, and TGF-β than SEVs from HDs. These levels correlated with tumor stage and HPV status. SEVs downregulated NKG2D expression on primary NK cells. HNC SEVs accelerated CD8+ T cell death compared to HD SEVs. This study suggests that UCopt is preferable when isolation of a high particle-to-protein load is required. Especially PD-L1 and FasL on SEVs hold substantial potential as diagnostic biomarkers.

Small extracellular vesicles - A host for advanced bioengineering and "Trojan Horse" of non-coding RNAs

Small extracellular vesicles (sEVs) are a type of membranous vesicles that can be released by cells into the extracellular space. The relationship between sEVs and non-coding RNAs (ncRNAs) is highly intricate and interdependent. This symbiotic relationship plays a pivotal role in facilitating intercellular communication and holds profound implications for a myriad of biological processes. The concept of sEVs and their ncRNA cargo as a "Trojan Horse" highlights their remarkable capacity to traverse biological barriers and surreptitiously deliver their cargo to target cells, evading detection by the host-immune system. Accumulating evidence suggests that sEVs may be harnessed as carriers to ferry therapeutic ncRNAs capable of selectively silencing disease-driving genes, particularly in conditions such as cancer. This approach presents several advantages over conventional drug delivery methods, opening up new possibilities for targeted therapy and improved treatment outcomes. However, the utilization of sEVs and ncRNAs as therapeutic agents raises valid concerns regarding the possibility of unforeseen consequences and unintended impacts that may emerge from their application. It is important to consider the fundamental attributes of sEVs and ncRNAs, including by an in-depth analysis of the practical and clinical potentials of exosomes, serving as a representative model for sEVs encapsulating ncRNAs.

Exosomes in Cancer Progression and Therapy Resistance: Molecular Insights and Therapeutic Opportunities

The development of therapy resistance still represents a major hurdle in treating cancers, leading to impaired treatment success and increased patient morbidity. The establishment of minimally invasive liquid biopsies is a promising approach to improving the early diagnosis, as well as therapy monitoring, of solid tumors. Because of their manifold functions in the tumor microenvironment, tumor-associated small extracellular vesicles, referred to as exosomes, have become a subject of intense research. Besides their important roles in cancer progression, metastasis, and the immune response, it has been proposed that exosomes also contribute to the acquisition and transfer of therapy resistance, mainly by delivering functional proteins and RNAs, as well as facilitating the export of active drugs or functioning as extracellular decoys. Extensive research has focused on understanding the molecular mechanisms underlying the occurrence of resistance and translating these into strategies for early detection. With this review, we want to provide an overview of the current knowledge about the (patho-)biology of exosomes, as well as state-of-the-art methods of isolation and analysis. Furthermore, we highlight the role of exosomes in tumorigenesis and cancer treatment, where they can function as therapeutic agents, biomarkers, and/or targets. By focusing on their roles in therapy resistance, we will reveal new paths of exploiting exosomes for cancer diagnosis and treatment.

Small extracellular vesicle TGF-β in cancer progression and immune evasion

Transforming growth factor-β (TGF-β) is a well-known cytokine that controls various processes in normal physiology and disease context. Strong preclinical and clinical literature supports the crucial roles of the TGF-β in several aspects of cancer biology. Recently emerging evidence reveals that the release of TGF-β from tumor/immune/stromal cells in small extracellular vesicles (sEVs) plays an important part in tumor development and immune evasion. Hence, this review aims to address the packaging, release, and signaling pathways of TGF-β carried in sEVs (sEV-TGF-β) in cancer, and to explore its underpinning roles in tumor development, growth, progression, metastasis, etc. We also highlight key progresses in deciphering the roles of sEV-TGF-β in subverting anti-tumor immune responses. The paper ends with a focus on the clinical significance of TGF-β carried in sEVs and draws attention to its diagnostic, therapeutic, and prognostic importance.

Single-cell transcriptome analysis indicates fatty acid metabolism-mediated metastasis and immunosuppression in male breast cancer

Male breast cancer (MBC) is a rare but aggressive malignancy with cellular and immunological characteristics that remain unclear. Here, we perform transcriptomic analysis for 111,038 single cells from tumor tissues of six MBC and thirteen female breast cancer (FBC) patients. We find that that MBC has significantly lower infiltration of T cells relative to FBC. Metastasis-related programs are more active in cancer cells from MBC. The activated fatty acid metabolism involved with FASN is related to cancer cell metastasis and low immune infiltration of MBC. T cells in MBC show activation of p38 MAPK and lipid oxidation pathways, indicating a dysfunctional state. In contrast, T cells in FBC exhibit higher expression of cytotoxic markers and immune activation pathways mediated by immune-modulatory cytokines. Moreover, we identify the inhibitory interactions between cancer cells and T cells in MBC. Our study provides important information for understanding the tumor immunology and metabolism of MBC.

Modulation of PD‑L1 expression by standard therapy in head and neck cancer cell lines and exosomes

Although checkpoint inhibitors (CPI) have recently extended the treatment options and improved clinical response of advanced stage head and neck squamous cell carcinoma (HNSCC), treatment success remains unpredictable. Programmed cell death ligand‑1 (PD‑L1) is a key player in immunotherapy. Tumor cells, and exosomes derived therefrom, are carriers of PD‑L1 and efficiently suppress immune responses. The aim of the present study was to analyze the influence of established therapies on PD‑L1 expression of HNSCC cell lines and their exosomes. The HNSCC cell lines, UM‑SCC‑11B, UM‑SCC‑14C and UM‑SCC‑22C were treated with fractionated radiotherapy (RT; 5x2 Gy), cisplatin (CT) and cetuximab (Cetux) as monotherapy, or combined therapy, chemoradiotherapy (CRT; RT and CT) or radioimmunotherapy (RT and Cetux). The expression of PD‑L1 and phosphorylated (p)ERK1/2 as a mediator of radioresistance were assessed using western blotting, immunohistochemistry and an ex vivo vital tissue culture model. Additionally, exosomes were isolated from concentrated supernatants of the (un‑)treated HNSCC cell lines by size exclusion chromatography. Exosomal protein expression levels of PD‑L1 were detected using western blotting and semi‑quantitative levels were calculated. The functional impact of exosomes from the (un‑)treated HNSCC cell lines on the proliferation (MTS assay) and apoptosis (Caspase 3/7 assay) of the untreated HNSCC cell lines were measured and compared. The HNSCC cell lines UM‑SCC‑11B and UM‑SCC‑22B showed strong expression of pERK1/2 and PD‑L1, respectively. RT upregulated the PD‑L1 expression in UM‑SCC‑11B and UM‑SCC‑14C and in exosomes from all three cell lines. CT alone induced PD‑L1 expression in all cell lines. CRT induced the expression of PD‑L1 in all HNSCC cell lines and exosomes from UM‑SCC‑14C and UM‑SCC‑22B. The data indicated a potential co‑regulation of PD‑L1 and activated ERK1/2, most evident in UM‑SCC‑14C. Exosomes from irradiated UM‑SCC‑14C cells protected the unirradiated cells from apoptosis by Caspase 3/7 downregulation. The present study suggested a tumor cell‑mediated regulation of PD‑L1 upon platinum‑based CRT in HNSCC and in exosomes. A co‑regulation of PD‑L1 and MAPK signaling response was hypothesized.

Tumor gene signatures that correlate with release of extracellular vesicles shape the immune landscape in head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCCs) evade immune responses through multiple resistance mechanisms. Extracellular vesicles (EVs) released by the tumor and interacting with immune cells induce immune dysfunction and contribute to tumor progression. This study evaluates the clinical relevance and impact on anti-tumor immune responses of gene signatures expressed in HNSCC and associated with EV production/release. Expression levels of two recently described gene sets were determined in The Cancer Genome Atlas Head and Neck Cancer cohort (n = 522) and validated in the GSE65858 dataset (n = 250) as well as a recently published single-cell RNA sequencing dataset (n = 18). Clustering into HPV(+) and HPV(-) patients was performed in all cohorts for further analysis. Potential associations between gene expression levels, immune cell infiltration, and patient overall survival were analyzed using GEPIA2, TISIDB, TIMER, and the UCSC Xena browser. Compared to normal control tissues, vesiculation-related genes were upregulated in HNSCC cells. Elevated gene expression levels positively correlated (P < 0.01) with increased abundance of CD4(+) T cells, macrophages, neutrophils, and dendritic cells infiltrating tumor tissues but were negatively associated (P < 0.01) with the presence of B cells and CD8(+) T cells in the tumor. Expression levels of immunosuppressive factors NT5E and TGFB1 correlated with the vesiculation-related genes and might explain the alterations of the anti-tumor immune response. Enhanced expression levels of vesiculation-related genes in tumor tissues associates with the immunosuppressive tumor milieu and the reduced infiltration of B cells and CD8(+) T cells into the tumor.

Tumor-Derived Exosomes and the Role of Liquid Biopsy in Human Papillomavirus Oropharyngeal Squamous Cell Carcinoma

ABSTRACT

The global incidence of human papillomavirus-positive (HPV+) head and neck squamous cell carcinoma (HNSCC) has surged in recent decades, with HPV+ HNSCC accounting for >70% of oropharynx cancers in the United States. Its incidence in men has surpassed that of HPV+ cervical cancer in women, and reliable assays are needed for early detection and to monitor response to therapy. Human papillomavirus-positive OPSCC has a more favorable response to therapy and prognosis than HPV-negative (HPV-) HNSCC, motivating regimens to deintensify curative surgery or chemoradiotherapy protocols. A barrier to deintensifying and personalizing therapy is lack of reliable predictive biomarkers. Furthermore, HPV- HNSCC survival rates are static without reliable surveillance biomarkers available. The emergence of circulating plasma-based biomarkers reflecting the tumor-immune microenvironment heralds a new era in HNSCC diagnosis and therapy. We review evidence on tumor-derived extracellular vesicles (exosomes) as biomarkers for diagnosis, prognostication, and treatment in HPV+ and HPV- HNSCC.

Plasma-derived small extracellular vesicles unleash the angiogenic potential in head and neck cancer patients

BACKGROUND

In Head and neck cancer (HNC) angiogenesis is essential for tumor progression and metastasis. Small extracellular vesicles (sEVs) from HNC cell lines alter endothelial cell (EC) functions towards a pro-angiogenic phenotype. However, the role of plasma sEVs retrieved from HNC patients in this process is not clear so far.

METHODS

Plasma sEVs were isolated on size exclusion chromatography columns from 32 HNC patients (early-stage UICC I/II: 8, advanced-stage UICC III/IV: 24), 12 patients with no evident disease after therapy (NED) and 16 healthy donors (HD). Briefly, sEVs were characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), BCA protein assays and Western blots. Levels of angiogenesis-associated proteins were determined using antibody arrays. The interaction of fluorescently-labeled sEVs with human umbilical vein ECs was visualized by confocal microscopy. The functional effect of sEVs on tubulogenesis, migration, proliferation and apoptosis of ECs was assessed.

RESULTS

The internalization of sEVs by ECs was visualized using confocal microscopy. Based on antibody arrays, all plasma sEVs were enriched in anti-angiogenic proteins. HNC sEVs contained more pro-angiogenic MMP-9 and anti-angiogenic proteins (Serpin F1) than HD sEVs. Interestingly, a strong inhibition of EC function was observed for sEVs from early-stage HNC, NED and HD. In contrast, sEVs from advanced-stage HNC showed a significantly increased tubulogenesis, migration and proliferation and induced less apoptosis in ECs than sEVs from HD.

CONCLUSIONS

In general, plasma sEVs carry a predominantly anti-angiogenic protein cargo and suppress the angiogenic properties of ECs, while sEVs from (advanced-stage) HNC patients induce angiogenesis compared to HD sEVs. Thus, tumor-derived sEVs within the plasma of HNC patients might shift the angiogenic switch towards angiogenesis.

TGFβ carrying exosomes in plasma: potential biomarkers of cancer progression in patients with head and neck squamous cell carcinoma

OBJECTIVES

Contributions of TGFβ to cancer progression are well documented. However, plasma TGFβ levels often do not correlate with clinicopathological data. We examine the role of TGFβ carried in exosomes isolated from murine and human plasma as a contributor to disease progression in head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

The 4-nitroquinoline-1-oxide (4-NQO) mouse model was used to study changes in TGFβ expression levels during oral carcinogenesis. In human HNSCC, TGFβ and Smad3 protein expression levels and TGFB1 gene expression were determined. Soluble TGFβ levels were evaluated by ELISA and TGFβ bioassays. Exosomes were isolated from plasma using size exclusion chromatography, and TGFβ content was quantified using bioassays and bioprinted microarrays.

RESULTS

During 4-NQO carcinogenesis, TGFβ levels in tumour tissues and in serum increased as the tumour progressed. The TGFβ content of circulating exosomes also increased. In HNSCC patients, TGFβ, Smad3 and TGFB1 were overexpressed in tumour tissues and correlated with increased soluble TGFβ levels. Neither TGFβ expression in tumours nor levels of soluble TGFβ correlated with clinicopathological data or survival. Only exosome-associated TGFβ reflected tumour progression and correlated with tumour size.

CONCLUSIONS

Circulating TGFβ+ exosomes in the plasma of patients with HNSCC emerge as potential non-invasive biomarkers of disease progression in HNSCC.