The Cytotoxic and Immune-Regulatory Roles of CD8+T Cell-Derived Exosomes in Cancer: A Systematic Review.

The second most significant contributor to the global mortality rate resulting from non-communicable diseases is cancer. Cancer cells are recognized for their interactions with adjacent noncancerous cells, such as immune and stromal cells, within the tumor microenvironment, which play a crucial role in influencing tumor progression, metastasis, and resistance. T cell activation is a pivotal process that facilitates the immune system's ability to combat malignancies, characterized by a multi-step signaling cascade leading to T cell proliferation and differentiation. During this activation phase, T cells release a variety of extracellular vesicles, particularly exosomes, which serve as critical regulators of intercellular communication within the tumor microenvironment. These vesicles contain bioactive molecules such as proteins, microRNAs, and immunomodulatory factors that influence tumor growth, immune evasion, and therapeutic responses. CD8⁺T cell-derived exosomes (CD8⁺T-Exos) have been shown to inhibit tumor metastasis by carrying microRNAs that downregulate tumor-promoting genes while also enhancing immune responses by activating CD8⁺T lymphocytes. By elucidating the diverse functions of CD8⁺T-Exos, this review highlights their potential as both biomarkers and therapeutic agents in cancer treatment.