Comprehensive Proteomic Profiling of Triple-Negative Breast Cancer-Derived Small Extracellular Vesicles Unveiled PXDN and GGT5 as Novel Protein Markers Implicated in Oncogenic Signaling Networks

Breast cancer (BC) is the most prevalent
cancer and the second
leading cause of cancer-related mortality among women. Early detection
and treatment can significantly improve survival rates. The potential
application of small extracellular vesicles (sEVs) as biomarkers for
early BC diagnosis has gained increasing attention, primarily due
to their promise as a minimally invasive detection method. However,
the specific protein signatures of sEVs are still not well understood.
This study compared the proteomes of MDA-MB-231 and MCF-10A cells
with their respective sEVs and conducted cross-comparisons between
the two cell types and their sEV populations. Bioinformatic analyses
revealed that MDA-MB-231 cell-derived sEVs are enriched with proteins
involved in cancer growth and proliferation pathways. The proteins
from these pathways can offer a valuable resource for triple-negative
BC (TNBC) biomarkers. In this study, three proteins were selected
based on their unique presence in MDA-MB-231 cell-derived sEVs and
their association with pathways related to BC: peroxidasin homolog
(PXDN), glutathione hydrolase 5 proenzyme (GGT5), and plasminogen
activator inhibitor 1 (SERPINE1). These proteins were validated using
synthetic heavy-labeled peptides and mass spectrometry-based parallel
reaction monitoring, as well as Western blot analysis. This study
highlights the potential of sEV-based proteins as noninvasive biomarkers
for early TNBC detection, laying the groundwork for future diagnostic
studies.