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There are different subtypes of brain tumors, classified according to the origin of the abnormally proliferated glial cells. Glioblastoma multiforma (GBM) is the grade 4 of brain tumors, gliomas, with the least life expectancy. microRNAs (miRNAs) are small, single stranded, non-coding RNAs with 20-25 nt length with post-transcriptional gene regulatory activities. An altered expression of miRNAs is linked to developmental disorders and some diseases, most importantly cancers. miR-21 is a well-known microRNA, overexpressed in almost all cancer types, including brain tumors. It targets several genes with vital roles in cellular pathways involve in proliferation, invasion and metastatic behaviors. Exosomes are 30-100 nm extracellular vesicles which are packed with various molecules, including miRNAs. Here, we suppressed miR-21 expression level in HEK-293T cells by transfecting them with the miRZip-21 vector. However, when U87-MG cells were cultured in the presence of exosomes isolated from conditioned medium of engineered HEK-293T cells derived exosomes, we did not observe any suppressing effect on host cells’ miR-21 expression level. Moreover, by analyzing the effects of miRZip-21-enriched cell’s conditioned media on three other brain cell lines including 1321N1, A-172 and DAOY, cell type-specific effects of exocrine miRZip-21 were revealed. These data suggested that cell lines from different brain tumor subtypes could exert different responses to microRNA-based therapies, based on their cellular origin and clinical behaviors.

Alzheimer disease (AD) is a complex neurodegenerative disorder with no definite treatment. The expression of miR-29 family is significantly reduced in AD, suggesting a part for the family members in pathogenesis of the disease. The recent emergence of microRNA (miRNA)–based therapeutic approaches is emphasized on the efficiency of miRNA transfer to target cells. The endogenously made secretory vesicles could provide a biological vehicle for drug delivery. Characteristics such as small sizes, the ability to cross the blood–brain barrier, the specificity in binding to the right target cells, and most importantly the capacity to be engineered as drug carriers have made exosomes desirable vehicles to deliver genetic materials to the central nervous system. Here, we transfected rat bone marrow mesenchymal stem cells and HEK-293T cells (human embryonic kidney 293 cells) with recombinant expression vectors, carrying either mir-29a or mir-29b precursor sequences. A significant overexpression of miR-29 and downregulation of their targets genes, BACE1 (β-site amyloid precursor protein cleaving enzyme 1) and BIM [Bcl−2 interacting mediator of cell death (BCL2-like 11)], were confirmed in the transfected cells. Then, we confirmed the packaging of miR-29 in exosomes secreted from the transfected cells. Finally, we investigated a possible therapeutic effect of the engineered exosomes to reduce the pathological effects of amyloid-β (Aβ) peptide in a rat model of AD. Aβ–treated model rats showed some deficits in spatial learning and memory. However, in animals injected with miR-29–containing exosomes at CA1 (cornu ammonis area), the aforementioned impairments were prevented. In conclusion, our findings provide a new approach for the packaging of miR-29 in exosomes and that the engineered exosomes might have a therapeutic potential in AD.

Objective(s): Despite the good results of anticancer activities by curcumin, there are some hurdles that limit the use of curcumin as an anticancer agent. Many methods were examined to overcome this defect like the use of the dendrosomal curcumin (DNC). There is increasing evidence that miRNAs play important roles in biological processes. In this study, we focus on the roles of microRNA-21 in the anti-cancer effects of DNC in breast cancer. Materials and Methods: Also, we have used different methods such as MTT, apoptosis, cell cycle analysis, transwell migration assay and RT-PCR to find out more. Results: We observed that miR-21 decreased apoptotic cells in both cells (from 6.35% to 0.34 % and from 7.72% to 1.32% orderly) and DNC increased it. As well as, our findings indicated that cell migration capacity was increased by miR-21 over expression and was decreased by DNC. The combination of miR-21 vector transfection and DNC treatment showed lower percentage of apoptotic cells or a higher level of penetration through the membrane compared with DNC treatment alone. Furthermore, DNC induced a marked increase in the number of cells in sub G1/G1 phase and a decrease in G2/M phase of the cell cycle in both; but, we observed reverse results compared it, after transfection with miR-21 vector. Conclusion: We observed that miR-21 suppress many aspects of anti-cancer effects of DNC in breast cancer cells, it seems that co-treatment with DNC and mir-21 down-regulation may provide a clinically useful tool for drug-resistance breast cancer cells.

Glioblastoma multiforme (GBM) is a grade 4 and the most aggressive form of glioma, with a poor response to current treatments. The expression of microRNAs (miRNAs) is widely dysregulated in various cancers, including GBM. One of the overexpressed miRNAs in GBM is miR-21 which promotes proliferation, invasion and metastatic behaviors of tumor cells. With a size of 30–100 nm, the extracellular vesicles “exosomes” have emerged as a novel and powerful drug delivering systems. Recently, exosomal transfer of miRNAs or anti-miRNAs to tumor cells has introduced a new approach for therapeutic application of miRNAs to combat cancer. Here, we have tried to down-regulate miR-21 expression in glioma cell lines, U87-MG, and C6, by using engineered exosomes, packed with a miR-21-sponge construct. Our data revealed that the engineered exosomes have the potential to suppress miR-21 and consequently to upregulate miR-21 target genes, PDCD4 and RECK. Interestingly, in cells treated with miR-21-sponge exosomes we observed a decline in proliferation and also an elevation in apoptotic rates. Finally, in a rat model of glioblastoma, administrating exosomes loaded with a miR-21-sponge construct leads to a significant reduction in the volume of the tumors. In brief, our findings suggest a new therapeutic strategy to use engineered exosomes to deliver a miR-21-sponge construct to GBM cells, in order to block its malignant behavior.

Purpose: To investigate a potential alteration in the expression levels of transforminggrowth factor β (TGF-β) and miR-21 in bladder cancer tissues.Material and Methods: Using real-time polymerase chain reaction (PCR) method, weexamined a potential correlated expression of miR-21 and TGF-β variants in 30 bladdertumors and their marginal/non-tumor biopsy specimens obtained from the same patients.Results: Our data revealed a significant down-regulation of TGF-β variants (P = .03) alongwith a non-significant alteration in the expression of miR-21 in tumor vs. non-tumor samples.However, in contrast to low-grade tumors, the expression of miR-21 was upregulatedin high-grade ones, and the expression level can efficiently discriminate low-grade tumorsfrom high-grade ones (P = .03).Conclusion: In accordance to the observed similarity between TGF-β variants and miR-21gene expression alterations in bladder tumors, treating 5637 bladder cancer cell line withTGF-β recombinant protein caused a significant upregulation of miR-21. The later findingfurther confirmed a correlated expression of TGF-β and miR-21 in bladder tumors.