In glioblastoma cells, the miR-9 masking oligonucleotide prevented the interaction of miR-9 with its target PTCH1 and overcame temozolomide resistance, confirming the therapeutic potential of these RNA agents . In addition, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated nuclease 9 (Cas9) system has been demonstrated to efficiently inhibit the expression of oncogenic miRs, including miR-17, miR-21, miR-141, and miR-3188 to reduce tumor cell proliferation, invasion, but to enhance apoptosis [112,113]. chemical nature, which allows specific pharmacological targeting, miRs are attractive targets for anti-tumor therapy. In this review, we cover a recent update on our understanding of dysregulated miRs in the TME and provide an overview of how these miRs are involved in current cancer-therapeutic approaches from bench to bedside. NSCLC mouse model, co-delivery of let-7 and miR-34 by using the same lipid nanoparticle carrier resulted in a significantly reduced tumor burden . Due to their strong anti-tumor effects, lipid nanoparticle-encapsulated miR-34 mimics were tested in a phase I clinical trial (“type”:”clinical-trial”,”attrs”:”text”:”NCT01829971″,”term_id”:”NCT01829971″NCT01829971) in several solid and hematological malignancies. Moreover, delivery of members of the miR-200 family using 1,2 dioleoyl-sn glycero-3 phosphatidylcholine (DOPC)-lipid nanoparticles in orthotopic mouse models of ovarian (miR-200a/b), basal-like breast (miR-141), and lung (miR-200a/b) cancers was shown to significantly reduce tumor nodules and metastasis . In a parallel study, Cortez et al. demonstrated that miR-200c upregulation increases intracellular reactive oxygen species by regulating the oxidative stress response genes peroxiredoxin 2 (PRDX2,) NF E2 related factor 2 (NRF2), and sestrin 1 (SESN1) . The systemic delivery of miR-200c in a xenograft lung cancer model fosters tumor cell apoptosis and increased radiosensitivity. miR-mimics have also been used in preclinical trials to induce repolarization of TAMs. In a mouse model of lung cancer, the combinatorial delivery of the pro-inflammatory miR-125b mimic together with wt-p53 cells using CD44/epidermal growth factor receptor (EGFR)-targeted hyaluronic acid-based nanoparticles repolarized TAMs towards the M1 phenotype and inhibited tumor growth . Similarly, the targeted delivery of miR-99b in HCC or subcutaneous Lewis lung cancer mice re-educated TAMs from M2 to M1 phenotype by targeting B-Ras2 and/or mTOR, thereby enhancing immune surveillance and impeded tumor growth . In a xenograft mouse model of oral squamous cell carcinoma, overexpression of miR-34a-5p by miR mimic significantly inhibited tumorigenesis . 3.2. Suppression of OncomiRs It is well accepted that oncogenic miRs are increased in cancer tissues and inhibit important tumor-suppressor genes, resulting in enhanced cell turnover and cell Alizapride HCl proliferation. Inhibition of oncogenic miRs has become an important area for gene therapy since the restoration of tumor suppressor genes is the pre-requisite to restore normal cellular homeostasis. Thus, inhibition of oncomiRs represents a useful strategy in the Alizapride HCl fight against cancer. Several different methods have been established to either prevent the binding of oncomiRs to their targets or interfere with the mRNA targets without affecting the miR activity. Synthetic antisense oligonucleotides (ASOs; anti-miR) are single stranded nucleic acids that are around 20-25 bases long. They are designed to complementarily bind to their mature miRs targets, thereby preventing the interaction of that miR with its mRNA target and the consequent normal translation . ASOs can be structurally or chemically modified to make them more resistance to nuclease-mediated degradation, enhance their penetration across the cell membrane, binding affinity, and thermal and metabolic stability [95,96]. Recently, a comprehensive guide FLNA for designing anti-miR oligonucleotides has been Alizapride HCl reported . The therapeutic potential of ASOs have been shown in different types of cancer in vitro and in vivo. For example, inhibition of the anti-apoptotic miR-21 by anti-miR oligonucleotides activates apoptosis and reduces tumor growth in breast cancer . Griveau et al. showed that miR-21 can be silenced by locked nucleic acid (LNA)-modified oligonucleotides in glioblastoma, resulting in reduced cell viability and enhanced intracellular caspase amounts . There are also some studies showing that ASOs can be used to repolarize TAMs towards a pro-tumoral phenotype, thereby reducing tumor burden. For instance, miR-100 is highly expressed in TAMs and maintains pro-tumoral functions by targeting the mTOR signaling pathway. Intra-tumoral treatment Alizapride HCl of miR-100 antagomiR together with cisplatin significantly reduced tumor metastasis and the invasion capacity in a 4T1 mouse breast cancer model Alizapride HCl . MiR-21 has been reported to be involved in the metabolic alteration of CAFs in vitro. Treatment of CAFs with a miR-21 antagomiR upon indirect coculture with the pancreatic cancer cell line BxPc-3.