miRNAs in the Regulation of Cancer Immune Response: Effect of miRNAs on Cancer Immunotherapy

SIMPLE SUMMARY: Cancer is the deadliest disease affecting humans, with more than 14 million cases and 8 million deaths. A successful therapeutic interception of cancer is urgently required. We have reviewed the immunologic involvement of various types of cancers that are well substantiated in the existing literature. Interestingly, multiple signalling pathways of the immune system could be modulated with miRNAs (noncoding RNAs of 22 nucleotides), such as miR-19a-3p, which induces macrophage polarization and the amelioration of cancer progression and metastasis. Developing a specific profile of miRNA within immune cells could also help in diagnosis and treatment. miRNA-based immune therapeutics that help to reduce cancer immune escape hold possibilities for developing cancer chemotherapy. ABSTRACT: In the last few decades, carcinogenesis has been extensively explored and substantial research has identified immunogenic involvement in various types of cancers. As a result, immune checkpoint blockers and other immune-based therapies were developed as novel immunotherapeutic strategies. However, despite being a promising therapeutic option, immunotherapy has significant constraints such as a high cost of treatment, unpredictable toxicity, and clinical outcomes. miRNAs are non-coding, small RNAs actively involved in modulating the immune system’s multiple signalling pathways by binding to the 3′-UTR of target genes. miRNAs possess a unique advantage in modulating multiple targets of either the same or different signalling pathways. Therefore, miRNA follows a ‘one drug multiple target’ hypothesis. Attempts are made to explore the therapeutic promise of miRNAs in cancer so that it can be transported from bench to bedside for successful immunotherapeutic results. Therefore, in the current manuscript, we discussed, in detail, the mechanism and role of miRNAs in different types of cancers relating to the immune system, its diagnostic and therapeutic aspect, the effect on immune escape, immune-checkpoint molecules, and the tumour microenvironment. We have also discussed the existing limitations, clinical success and the prospective use of miRNAs in cancer.