Extracellular Vesicle (EV) Survivin for Cancer Diagnostics and Therapeutics: A Review.

Survivin, an important inhibitor of apoptosis protein, contributes to cancer cells' resistance to apoptosis, proliferation, and survival. It is a promising biomarker and therapeutic target due to being highly expressed in cancer cells relative to normal cells and universally expressed in almost all cancer types. Cancer cells release survivin to the tumour microenvironment (TME) not only as a free protein but also encapsulated in extracellular vesicles (EVs), especially small EVs (sEVs). The release of encapsulated survivin from cancer cells can be taken up by neighbouring cells, eliciting pathological responses such as tumorigenesis and metastasis. Consequently, EV survivin holds potential as a diagnostic, prognostic, and therapeutic biomarker for several types of cancer, including breast cancer, prostate cancer, pancreatic cancer, and glioblastoma. EV survivin expression is significantly elevated in cancer patients and correlates with unfavourable clinicopathologic parameters. Although no clinical studies have explored EV survivin as a therapeutic target, future research should explore survivin-based therapies in combination with EV-targeting therapies to effectively disrupt its roles in tumorigenesis and metastasis.