Non-Coding RNA

Background/Objectives: Bone marrow mesenchymal stromal cells (MSCs) are therapeutic cells that adopt an immunomodulatory phenotype when exposed to pro-inflammatory cytokines. Recent research efforts uncovered that many therapeutic benefits of MSCs can be attributed to the secretion of extracellular vesicles (EVs) such as exosomes, small membrane vesicles of endocytic origin present in the cellular secretome. EVs’ formation and release are impacted by the autophagy pathway, which recycles proteins and organelles via lysosomal degradation. Methods: To evaluate how modulation of autophagy affects properties of MSC EVs enriched in exosomes under pro-inflammatory conditions, we treated the cells with either tamoxifen (TX) or chloroquine (CQ), two drugs known to stimulate or inhibit autophagy, respectively, together with IFNγ. MSC EVs enriched in exosomes were then purified from serum-free media, and their immunoregulatory properties were evaluated ex vivo using activated CD4 T cells; small RNA sequencing was also conducted to determine EVs’ microRNA content. Results: Our data indicate that MSCs treated with CQ + IFNγ yield EVs that possess somewhat higher capacity to decrease T cell proliferation compared to other EVs. Small RNA sequencing revealed that, although similar microRNAs were found in EVs isolated from all treated cells, the treatments exerted more effect on the levels of multiple microRNAs that are known to regulate either cancer or inflammation-related biological pathways in target cells. Conclusions: Overall, we conclude that the co-treatment of MSCs with TX or CQ in the presence of pro-inflammatory cytokine IFNγ has the potential to modulate microRNA content of EVs, potentially affecting biological properties of such EVs and their effect on target cells.

Background: Transposable elements are normally silenced by epigenetic mechanisms; however, during malignant transformation, epigenetic alterations enable transposons to produce functional molecules like miRNAs. Among these, LINE-2 (L2) elements can generate miRNAs capable of regulating key genes, including tumor suppressors. Two L2-derived miRNAs, miR-28 and miR-708, have been linked to lung cancer, yet the mechanisms underlying their dysregulation remain poorly understood. Our study reveals how genomic context contributes to aberrant gene expression through comprehensive bioinformatic analyses. Methods: Using bioinformatics analysis, we evaluated the expression of miR-28 and miR-708 in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) datasets from TCGA. Further, we assessed the expression and methylation status of miR-28 and miR-708 host genes, LPP and TENM4, respectively, TENM4 using computational tools. Finaly, we searched for potential candidate tumor suppressor genes targeted by miR-28 and miR-708, which are downregulated in LUAD and LUSC. Results: We found that intragenic L2-derived miR-28 and miR-708 are significantly upregulated in LUAD and LUSC. While TENM4 gene also displays a marked increase in expression in LUAD and LUSC, in tumor versus normal tissue, this difference is less obvious for the LPP gene. We suggest that such dysregulations in expression might be linked to specific methylation patterns of their genomic locations. Furthermore, we emphasize that miR-28 and miR-708 might contribute to lung cancer pathogenesis by targeting key tumor suppressor genes. Conclusions: Alterations in the methylation status of L2-miRNAs genomic loci might result in elevated levels of miRNAs and subsequent targeting of tumor suppressor genes with potential implications in lung cancer pathogenesis.

Bone metastasis is a common and severe complication in advanced stages of breast cancer (BC) that is characterised by limited treatment options and poor patient prognosis. MicroRNAs (miRNAs) are a large class of regulatory small non-coding RNAs (ncRNAs) expressed by cells. Moreover, miRNAs can be released by cells into the blood and lymphatic streams, acting as distant cell-to-cell communicators. Of note, miRNAs have pivotal roles in the metastatic progression of BC to bone. This review summarises the most recent findings on miRNAs and their mRNA targets in driving BC bone metastasis. Furthermore, the potential clinical uses of miRNAs as future therapeutic targets/agents or biomarkers for BC bone metastasis are discussed.