Search Results (4)

Background and Objectives: Aggressive cancer development is characterized by rapid tumor growth and progressive immune dysfunction. Tumor-derived microRNAs (miRNAs) emerge as master regulators of both malignant transformation and immune evasion, making them promising therapeutic targets. Using the highly aggressive CT-26 peritoneal adenomatosis model, this study explored the potential of selective miRNA inhibition to simultaneously suppress tumor growth and overcome immunosuppression. Methods and Results: Our results revealed that inhibition of miR-155, miR-21, and miR-17 by methylsulfonyl phosphoramidate (mesyl) oligonucleotides exhibited markedly different therapeutic profiles. miR-155 inhibition demonstrated minimal efficacy. miR-21 suppression provided early tumor regression and prevented cancer-associated thymic atrophy, translating into extended survival. miR-17 inhibition displayed delayed but superior tumor growth inhibition, significantly reducing pathologically elevated polymorphonuclear myeloid-derived suppressor cell (MDSC) populations, and nearly doubled animal lifespan. Combination therapy targeting all three miRNAs integrated these complementary mechanisms, maintaining consistent anti-tumor efficacy across early and late stages while providing thymic protection and MDSC reduction. Importantly, therapeutic responses in vivo substantially exceeded predictions based on in vitro tumor cell proliferation and motility measurements, revealing critical contributions of systemic immunomodulation. Conclusions: These findings demonstrate that miRNA inhibition reshapes tumor–immune interactions, positioning anti-miRNA therapeutics as immunomodulatory agents for effective colorectal cancer treatment. Full article

Background: Chemotherapy remains one of the main approaches for treating malignant tumors, but repeated exposure to cytostatics leads to multidrug resistance (MDR), increasing tumor aggressiveness and reducing therapeutic efficacy. Identifying adjuvant agents that restore tumor sensitivity to drugs while minimizing toxicity is a cornerstone challenge today. This study aimed to investigate the potential of mesyl phosphoramidate antisense oligonucleotides (µ-ASOs) targeting miR-17, miR-21, and miR-155 as agents for enhancing the efficacy of cisplatin (Cis) and doxorubicin (Dox) in MDR-positive human epidermoid carcinoma KB-8-5 cells. Methods: Optimal regimens for the simultaneous application of µ-ASOs and Dox or Cis in KB-8-5 cells, including a concentration-dependent analysis and the type of compound interaction in combinations (synergy/additivity/antagonism), were studied using the MTT assay. Antiproliferative effects of the combinations were assessed using the real-time cell monitoring xCELLigence system. The potential molecular mechanism underlying KB-8-5 cell sensitization to cytostatics was investigated using RT-PCR and Western blot hybridization, supported by bioinformatic reconstruction of the gene network. Results: The most effective combinations including µ-ASOs targeting miR-21 and miR-17 together with Cis or Dox demonstrated additive to moderately synergistic effects on KB-8-5 cell viability (HSA synergy score = 4.8–8.7). The co-application of µ-ASOs allowed a 5- to 20-fold reduction in the dose of cytostatics, while maintaining a strong antiproliferative effect of 70–95%. Sensitization of KB-8-5 cells to Cis or Dox following µ-ASO treatment was mediated by a 1.5- to 3-fold decrease in the levels of the well-known MDR marker ABCB1 as well as the newly identified MDR-associated targets ZYX, TUBA4A, and SEH1L. Conclusions: miRNA-targeted mesyl phosphoramidate oligonucleotides are effective tools for overcoming resistance to the clinically approved chemotherapeutics cisplatin and doxorubicin. The relationship between miR-21, miR-17, and miR-155 and the novel MDR markers such as SEH1L, TUBA4A, and ZYX was revealed, thereby expanding the current understanding of the molecular mechanisms underlying tumor cell resistance to chemotherapy. Full article

Colorectal cancer (CRC) remains one of the most aggressive and therapeutically resistant malignancies worldwide. This study examined the molecular mechanisms underlying the anti-oncogenic activity of methanesulfonyl phosphoramidate-modified antisense oligonucleotides (µ-ASOs) targeting miR-21, miR-17, and miR-155, which represent critical oncogenic drivers in CRC. Using human colorectal adenocarcinoma Caco-2 cells transfected with either individual µ-ASOs or their triple combination, we assessed target miRNA downregulation, antiproliferative and anti-migratory activities, and performed extensive proteomic profiling. Protein–protein interaction network analysis of differentially expressed proteins (DEPs) revealed that, beyond modulation of core metabolic processes, each µ-ASO exhibited distinct effects: µ-21 predominantly affected apoptosis, cell cycle, and DNA repair; µ-17 influenced proliferation and chaperone responses; and µ-155 modulated intracellular transport and immune regulation. Combination treatment elicited a unique proteomic signature partially overlapping with monotherapies. The proteomic analysis revealed several validated and putative miRNA-targeted DEPs, including both established and novel candidates in the CRC context: RPL31, CCT2, and CDC37 (miR-21); DNM2, SNRPN, NUP98, and NUP85 (miR-17); as well as RPL17 (miR-155). Expression of these targets correlated with favorable clinical outcomes in CRC patients. This work provides the first comprehensive mechanistic insight into antisense oligonucleotide-mediated miRNA suppression in Caco-2 colorectal adenocarcinoma cells and expands the miRNA target landscape. Full article

Rational combinations of sequence-specific inhibitors of pro-oncogenic miRNAs can efficiently interfere with specific tumor survival pathways, offering great promise for targeted therapy of oncological diseases. Herein, we uncovered the potential of multicomponent therapy by double or triple combinations of highly potent mesyl phosphoramidate (µ) antisense oligodeoxynucleotides targeted to three proven pro-oncogenic microRNAs—miR-17, miR-21, and miR-155. A strong synergism in the inhibition of proliferation and migration of B16 melanoma cells was demonstrated in vitro for pairs of µ-oligonucleotides, which resulted in vivo in profound inhibition (up to 85%) of lung metastases development after intravenous injection of µ-oligonucleotide-transfected B16 cells in mice. A clear benefit of µ-21-ON/µ-17-ON and µ-17-ON/µ-155-ON/µ-21-ON combination antitumor therapy was shown for the lymphosarcoma RLS₄₀ solid tumor model. In vivo administration of the µ-17-ON/µ-155-ON/µ-21-ON cocktail into RLS₄₀-bearing mice elicited fourfold delay of tumor growth as a result of strong inhibition of tumor mitotic activity. It was discovered that the cocktail of µ-21-ON/µ-17-ON/µ-155-ON led to a twofold decrease in total destructive changes in murine liver, which indicates both the reduction in toxic tumor burden and the absence of specific toxicity of the proposed therapy. Full article