microRNAs as Regulators of the Immune Response and Their Potential Therapeutic Applications in Cancer.

MicroRNAs (miRNAs) are small non-coding RNAs that have emerged as critical regulators of gene expression and key cellular processes in cancer, including tumor cell proliferation, survival, metastasis, and both innate and adaptive immune responses within the tumor microenvironment. Through their ability to modulate immune cell development, differentiation, polarization, antigen presentation, cytokine signaling and immune checkpoint expression, miRNAs play a vital role in shaping immune responses and represent attractive therapeutic candidates for remodeling the tumor immune microenvironment. This review provides a comprehensive overview of the mechanisms through which miRNAs regulate anti-tumor immunity and contribute to immune evasion with particular emphasis on their role in modulating major immune checkpoint pathways, including PD-1/PD-L1, CTLA-4, LAG-3, TIM-3 and CD28-mediated signaling. We further examine the contribution of miRNAs to therapeutic resistance and discuss their potential integration with immune checkpoint blockade, chemotherapy, PARP inhibitors and targeted therapies to enhance antitumor efficacy and overcome treatment resistance. Recent advances in spatial transcriptomics and computational approaches have expanded our understanding of miRNA-mediated regulatory networks at single-cell and tissue levels and provide new insights into tumor-immune interactions. In addition, we evaluate the current progress in the clinical development of miRNA-based therapeutics, including miRNA mimics and inhibitors and discuss the major challenges associated with efficient delivery, off-target effects, immunogenicity and patient heterogeneity. Collectively, the evidence highlights the growing potential of miRNAs as diagnostic biomarkers, therapeutic targets and therapeutic tools in cancer immunotherapy. Continued advances in RNA therapeutics, delivery technologies and multi-omics approaches are expected to accelerate the clinical translation of miRNA-based strategies for personalized cancer therapy.