[Association of miRNA-196b-5p and miRNA-99a-5p with autophagy and apoptosis in multiple myeloma cells]

Analysis of self-renewing and differentiation-related microRNAs and transcription factors in multilineage mouse hematopoietic stem/progenitor cells induced by 1,4-benzoquinone

Background

HSPCs are targets for benzene-induced hematotoxicity and leukemogenesis. However, benzene toxicity targeting microRNAs (miRNAs) and transcription factors (TF) that are involve in regulating self-renewing and differentiation of HSPCs comprising of different hematopoietic lineages remains poorly understood. In this study, the effect of a benzene metabolite, 1,4-benzoquinone (1,4-BQ) exposure, in HSPCs focusing on the self-renewing (miRNAs: miR-196b and miR-29a; TF: HoxB4, Bmi-1) and differentiation (miRNAs: miR-181a, TF: GATA3) pathways were investigated.

Methods

Freshly isolated mouse BM cells were initially exposed to 1,4-BQ at 1.25 to 5 µM for 24 h, followed by miRNAs and TF studies in BM cells. Then, the miRNAs expression was further evaluated in HSPCs of different lineages comprised of myeloid, erythroid and pre-B lymphoid progenitors following 7-14 days of colony forming unit (CFU) assay.

Results

Exposure to 1,4-BQ in BM cells significantly (p < 0.05) reduced the miR-196b (2.5 and 5 µM), miR-181a (1.25, 2.5 and 5 µM) and miR-29a (1.25 µM) along with upregulation of miR-29a at 2.5 µM. Meanwhile, 1,4-BQ exposure in HSPCs significantly increased the miR-196b expression level (p < 0.05) only in myeloid and pre-B lymphoid progenitors at 2.5 and 5 µM. Significant (p < 0.05) reduction in expression of miR-181a in myeloid (1.25 µM), erythroid (5 µM) progenitors along with miR-29a in myeloid (1.25 µM) and pre-B lymphoid (5 µM) progenitors were noted following exposure to 1,4-BQ. Meanwhile, increased expression of miR-181a was observed in pre-B lymphoid progenitor upon exposure to 1,4-BQ, but only at 5 µM. As for TF studies, expression of HoxB4 protein was significantly increased (p < 0.05) at all 1,4-BQ concentrations as compared to Bmi-1 and GATA3, which were significantly (p < 0.05) elevated starting at 2.5 µM of 1,4-BQ.

Conclusion

1,4-BQ induces aberration of miRNAs and transcription factors protein expression that are involved in regulating self-renewing and differentiation pathways of HSPCs. Moreover, epigenetic toxicity as evidenced from the miRNAs expression was found to be mediated by a lineage-driven mechanism. The role of cell lineage in governing the toxicity of 1,4-BQ in HSPCs lineages deserves further investigation.

Regulation of autophagy by miRNAs in human diseases

Autophagy is a homeostatic process designed to eliminate dysfunctional and aging organelles and misfolded proteins through a well-concerted pathway, starting with forming a double-membrane vesicle and culminating in the lysosomal degradation of the cargo enclosed inside the mature vesicle. As a vital sentry of cellular health, autophagy is regulated in every human disease condition and is an essential target for non-coding RNAs like microRNAs (miRNAs). miRNAs are short oligonucleotides that specifically bind to the 3'-untranslated region (UTR) of target mRNAs, thus leading to mRNA silencing, degradation, or translation blockage. This review summarizes the recent findings regarding the regulation of autophagy and autophagy-related genes by different miRNAs in various pathological conditions, including cancer, kidney and liver disorders, neurodegeneration, cardiovascular disorders, infectious diseases, aging-related conditions, and inflammation-related diseases. As miRNAs are being identified as prime regulators of autophagy in human disease, pharmacological molecules and traditional medicines targeting these miRNAs are also being tested in disease models, thus initiating a new series of therapeutic interventions targeting autophagy.

miR‑140‑5p inhibits the proliferation of multiple myeloma cells by targeting VEGFA

MicroRNA (miR)-140-5p is associated with the growth and metastasis of various tumor cell types, yet its role in multiple myeloma (MM) remains unclear. Therefore, the present study aimed to investigate the regulatory effect of miR-140-5p on MM. Reverse transcription-quantitative PCR analysis demonstrated that miR-140-5p was downregulated in MM cell lines, particularly in U266 and RPMI 8226 cells. A Cell Counting Kit-8, wound healing and Transwell assays, as well as flow cytometry indicated that a miR-140-5p mimic could suppress cell viability, migration and invasion. In addition, the mimic promoted apoptosis of U266 and RPMI 8226 cells. Western blot data demonstrated that transfection with miR-140-5p mimic significantly reduced the expression levels of Ki-67, cyclin D1, vimentin, Snail, matrix metalloproteinase (MMP)-2 and MMP-3. Moreover, as predicted by TargetScan7.2 and verified by luciferase activity assay, it was demonstrated that vascular endothelial growth factor A (VEGFA) was targeted by miR-140-5p. Further experiments indicated that VEGFA overexpression promoted cell viability, migration and invasion and suppressed apoptosis of MM cells, and that the miR-140-5p mimic partially reversed the effects of VEGFA overexpression. Therefore, miR-140-5p suppressed MM progression by targeting VEGFA. The present findings provide insight into potential therapeutic strategies for the treatment of MM.

MicroRNA-940 inhibits glioma progression by blocking mitochondrial folate metabolism through targeting of MTHFD2

The aggressiveness and recurrence of glioma are major obstacles for the treatment of this type of tumor. Further understanding of the molecular mechanisms of glioma is necessary to improve the efficacy of therapy. MicroRNAs have been widely studied in many human cancers. Here, we found that miR-940 was one of the primary downregulated miRNAs in clinical samples and glioma cell lines through bioinformatics analysis and qRT-PCR. Upregulating miR-940 expression significantly inhibited the proliferation and invasion and promoted apoptosis of U87 and U118 cells. In addition, experiments in vivo showed that upregulation of miR-940 expression inhibited xenograft growth. Methylenetetrahydrofolate dehydrogenase (MTHFD2), a dual-functional metabolic enzyme, is involved in the one-carbon metabolism of folate in mitochondria. We found MTHFD2 to be overexpressed in glioma tissues and our clinical samples by qRT-PCR and Western blot assays. Through TargetScan prediction and luciferase assays, we found that miR-940 directly targets MTHFD2. Upregulation of miR-940 expression inhibited the expression of MTHFD2 and led to intracellular one-carbon metabolism dysfunction. Furthermore, the antitumor effects of miR-940 could be attenuated by overexpression of MTHFD2. Together, the results of our study suggest that miR-940 may be a new therapeutic target for the treatment of glioma through targeting of MTHFD2.