Advances in miRNA-Mediated Bidirectional Crosstalk and Immune Evasion Mechanisms Between Lung Cancer Cells and CD8⁺ T...

Lung cancer ranks first in both incidence and mortality among all malignancies, and tumor microenvironment (TME)-induced CD8⁺ T cell exhaustion is a critical factor driving immune evasion and compromising the efficacy of immunotherapy. MicroRNAs (miRNAs), as key post-transcriptional regulators, shuttle between lung cancer cells and CD8⁺ T cells via extracellular vesicles (EVs), serving as critical communication hubs that reshape the TME. This review systematically synthesizes recent literature to summarize the regulatory patterns of miRNAs on functions of lung cancer cells and CD8⁺ T cells, and dissect the molecular mechanisms underlying miRNA-mediated bidirectional crosstalk between these two cell types. This review focuses on the dual-pronged immune evasion strategy employed by lung cancer cells to counteract CD8⁺ T cells. On the one hand, lung cancer cells aberrantly express endogenous miRNAs, such as miR-20a, miR-149-5p, and miR-326, to remodel their surface ligands and establish immune camouflage. On the other hand, they actively secrete EVs enriched in specific miRNAs, including miR-7108-3p, miR-651-5p, and miR-24-3p, which directly suppress CD8⁺ T cell function. Furthermore, lung cancer cells secrete additional miRNAs, notably miR-6794-5p, miR-708-5p, and miR-1234-3p, to reprogram other TME components, namely tumor-associated macrophages (TAMs), natural killer (NK) cells, and myeloid-derived suppressor cells (MDSCs). These reprogrammed cells, in turn, indirectly attenuate CD8⁺ T cells through a relay-like mechanism via immunosuppressive cytokines or surface checkpoint molecules produced by these cells. In addition, competing endogenous RNA (ceRNA) networks formed by long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in lung cancer cells regulate miRNA activity at multiple levels, further impairing the immune effector functions of CD8⁺ T cells. Conversely, activated CD8⁺ T cells also secrete miRNA-containing EVs, which deliver these miRNAs to tumor cells, thereby inhibiting tumor progression. Elucidation of this miRNA-based bidirectional communication network will not only advance our understanding of immune evasion mechanisms in lung cancer but also provide novel insights into cell-free immunotherapeutic approaches based on CD8⁺ T cell-derived vesicles.