Metformin-induced ablation of microRNA 21-5p releases Sestrin-1 and CAB39L antitumoral activities

Abstract

Metformin is a commonly prescribed type II diabetes medication that exhibits promising anticancer effects. Recently, these effects were found to be associated, at least in part, with a modulation of microRNA expression. However, the mechanisms by which single modulated microRNAs mediate the anticancer effects of metformin are not entirely clear and knowledge of such a process could be vital to maximize the potential therapeutic benefits of this safe and well-tolerated therapy. Our analysis here revealed that the expression of miR-21-5p was downregulated in multiple breast cancer cell lines treated with pharmacologically relevant doses of metformin. Interestingly, the inhibition of miR-21-5p following metformin treatment was also observed in mouse breast cancer xenografts and in sera from 96 breast cancer patients. This modulation occurred at the levels of both pri-miR-21 and pre-miR-21, suggesting transcriptional modulation. Antagomir-mediated ablation of miR-21-5p phenocopied the effects of metformin on both the clonogenicity and migration of the treated cells, while ectopic expression of miR-21-5p had the opposite effect. Mechanistically, this reduction in miR-21-5p enhanced the expression of critical upstream activators of the AMP-activated protein kinase, calcium-binding protein 39-like and Sestrin-1, leading to AMP-activated protein kinase activation and inhibition of mammalian target of rapamycin signaling. Importantly, these effects of metformin were synergistic with those of everolimus, a clinically relevant mammalian target of rapamycin inhibitor, and were independent of the phosphatase and tensin homolog status. This highlights the potential relevance of metformin in combinatorial settings for the treatment of breast cancer.

Uric acid and sphingomyelin enhance autophagy in iPS cell-originated cardiomyocytes through lncRNA MEG3/miR-7-5p/EGFR axis

“…The primers were evaluated by BLAST search (http://www.ncbi.nlm.nih.gov/Sitemap/ index.html#BLAST). [25]. The primary antibodies for GAPDH, P62, EGFR, AKT3, beclin-1 and autophagy related 7 (Atg7) were purchased from Santa Cruz Biotechnology (Santa Cruz Biotechnology, Dallas, TX).…”

Non-coding RNAs as Putative Biomarkers of Cancer-Associated Cachexia

“…Intriguingly, miR-21 represents one of the circulating miRNAs whose concentration is increased in the serum of patients with the most varied types of cancer, suggesting the potential use of miR-21 as non-invasive diagnostic markers (Wu et al, 2015;Pulito et al, 2017;Cui et al, 2019).…”

Long non-coding RNA PVT1 promotes proliferation and migration of pulmonary smooth muscle cells in pulmonary arterial hypertension through miR-140-5p/Fxr1 axis

“…Total protein was isolated from lung tissues and HPASMCs using cell lysis buffer (Thermo Fisher Scienti c, Shanghai, China). Western blots were performed as previously described [24]. The primary antibodies against proliferating cell nuclear antigen (PCNA, 1:1000), fragile X-related proteins 1 (Fxr1, 1:1000), cyclin A1 (1:1000), cyclin D1(1:1000), cyclin E1 (1:1000), and β-actin (1:5000) were obtained from Santa Cruz (Santa Cruz, Shanghai, China).…”

“…After transfection, HPASMCs were subjected to the wound-healing assay and the detailed procedure was previously described [24].…”