Page 29 - SRPSKO DRUŠTVO ISTRAŽIVAČA RAKA

SDIRSACR Oncology Insights

monitoring use cases.(8, 9)
EV assays are compared and contrasted with circulating tumor DNA/cell-free DNA approaches to establish
complementarity in detection and disease dynamics, particularly for risk stratification and longitudinal monitoring(10,
11). The manuscriptstresses scalable, selective isolation and single-particle analytics suitable for clinical pipelines, and
we underscore open methodological reporting as a doorway to reproducibility and meta-analysis across laboratories
(12).

Role of EVs in cancer
EVs play a significant role in cancer development, progression, and metastasis by facilitating cross-communication
between tumor cells and their environment. EVs carry diverse cargo such as proteins, nucleic acids, lipids, and
metabolites acting like messengers thereby enabling tumorigenesis, tumor growth, metastasis and drug resistance.
Cancer cell-derived EVs harbor oncogenic molecules like proteins, DNA fragments, and most forms of non-coding RNA
that influence the initial hallmarks of cancer such as proliferation, invasion, immune evasion, and drug resistance.
Modulation of the tumor microenvironment toward malignancy is one of the key functions of EVs. They initiate
angiogenesis by transporting pro-angiogenic factors like VEGF and IL-8 to endothelial cells, promoting vascular
remodeling and delivery of nutrients to tumors(13).
In metastasis, EVs are key for tumor-organotropism as they prepare far-away tissues for the colonization of tumor cells.
They reprogram immune and stromal cells to create a permissive pre-metastatic niche, typically by delivering integrins,
metalloproteinases, and miRNAs that re-organize the extracellular matrix and suppress local immune surveillance
(14). Additionally, EVs are the main immune escape mediators; e.g., cancer-derived EVs can carry PD-L1 or Fas ligand
to inhibit T-cell activation and induce apoptosis in cytotoxic lymphocytes, creating an immunosuppressive tumor
microenvironment (15).
One of the crucial and better-documented roles of EVs in cancer is related to therapeutic resistance. Drug-resistant
cancer cells secrete EVs that contain multidrug resistance proteins (e.g., P-glycoprotein), anti-apoptotic proteins,
and resistance-predictive microRNAs (e.g., miR-21, miR-222). These vesicles can be internalized by drug-sensitive
neighboring cells, spreading resistance features to the tumor cell population. Moreover, EVs can modulate drug
metabolizing pathways, efflux pump expression, and DNA repair mechanisms of target cells, rendering the drugs less
effective. Some EVs also act as decoys since they bind and sequester therapeutic antibodies or chemotherapeutic
drugs, hence diminishing their availability at the tumor site. This multiparameter ability of EVs in resistance not only
boosts tumor survival under therapeutic stress but also complicates clinical cancer treatment (16). Thus, EVs are not
only products of cancer cells, but also active components involved in mediating tumor progression, metastasis, and
drug resistance.

EVs as cancer biomarkers
EVs are promising candidates for cancer diagnosis as a rich source of biomarkers due to their high abundance, stability,
and ability to transport dense cargo of tumor-associated molecules. In nearly all bodily fluids, EVs encapsulate proteins,
lipids, DNA, and various types of RNAs that are reflective of the molecular profile of their cell of origin, e.g., cancer
cells (13), making them a studied source of biomarkers for non-invasive liquid biopsies. EVs are released early during
tumorigenesis, often before lesions or metastasis become apparent, which makes it possible to detect them in the
early stages (17). It has been demonstrated that specific EV cargo—specifically, miRNAs (e.g., miR-21, miR-10b), long
non-coding RNA, and glypican-1 (GPC1) proteins—can distinguish between cancer patients and healthy individuals
with excellent sensitivity and specificity. In pancreatic cancer, EVs that are positive for GPC1 and EV-associated miR-21
and miR-1246 have sensitivity of up to 84% and specificity of up to 89% (18, 19, 20). EVs level of certain micro RNAs can
offer a more a sensitive tool for stratification of and screening of cancer patients (PCa). miR-21 has been associated with
prostate cancer, however its level in EVs may serve as a more accurate noninvasive prognostic biomarker compared
with the whole plasma miR-21 for active monitoring of PCa patients (21).
EV-based biomarkers have been evaluated across several cancer types and biofluids, with assays ranging from RNA
and lipid profiling to single-particle phenotyping. These studies demonstrate diagnostic accuracy, stratification
potential, and monitoring capability in both preclinical and clinical settings (6, 7, 12, 22, 23, 24, 25, 26, 27, 28, 29, 30).
Representative examples are summarized in Table 1, organized by cancer type, EV source, analyte, methodology, and
reported performance.

Isolation and Reporting for Clinical Translation
Despite significant progress in the field, major challenges including the standardization of EV isolation, cargo
heterogeneity, and pre-analytical variability still need to be addressed before routine clinical implementation can
be achieved (32). Present EVs isolation approaches are very inefficient, time-consuming, and expensive. They are
generally based on ultracentrifugation, ultrafiltration, precipitation, or immunoaffinity-based exosome isolation. The

14