Metformin modulates oncogenic expression of HOTAIR gene via promoter methylation and reverses epithelial–mesenchymal transition in MDA‐MB‐231 cells

Abstract

Epithelial–mesenchymal transition (EMT) is a biological event, which critically regulates migration and invasion of cancer cells. EMT is regulated by several protein and nonprotein factors (such as noncoding RNAs). HOTAIR is an oncogenic long noncoding RNA that stimulates EMT in cancers. In the current study, we investigated the effect of metformin on EMT behavior and HOTAIR expression in MDA‐MB‐231 breast cancer cells. The minimal effective concentrations of metformin (10 and 20 mM) were obtained by the MTT test. Cell migration and invasion in the metformin‐containing medium were assayed in the scratch assay and transwell test. Meaningful decreases in both cell migration and invasion were observed in the presence of metformin. Vimentin, snail, β‐catenin, and HOTAIR transcripts were quantified by real‐time polymerase chain reaction (PCR). Reduction in the expression of vimentin, β‐catenin, and HOTAIR was detected as the result of metformin treatment, but the snail showed a constant expression. Western blottingrevealed the downregulation of vimentin and β‐catenin proteins. HOTAIR promoter methylation pattern was also investigated in metformin‐exposed cells using bisulfite sequencing PCR which the result showed differences in the methylation profile of CpG islands between the treated and untreated cells. In conclusion, metformin modulated oncogenic expression of the HOTAIR gene in the MDA‐MB‐231 cells. This downregulation was associated with the modification of promoter methylation patterns. Since HOTAIR induces EMT in breast cancer, HOTAIR decline might be one of the mechanisms by which metformin reverses EMT.

lncRNA MALAT1 participates in metformin inhibiting the proliferation of breast cancer cell

“…Actually, up‐regulation of HOTAIR, which binds lysine‐specific demethylase 1 (LSD1) and polycomb repressive complex 2 (PRC2), 39 was observed in the metformin‐treated cells. In addition, metformin was also showed to modulate the HOTAIR promoter methylation pattern in triple‐negative aggressive breast cancer cell line MDA‐MB‐231 40 . Therefore, modulating epigenetic regulators would be helpful to the repurposing metformin on breast cancer therapy.…”

“…In addition, metformin was also showed to modulate the HOTAIR promoter methylation pattern in triple-negative aggressive breast cancer cell line MDA-MB-231. 40 Therefore, modulating epigenetic regulators would be helpful to the repurposing metformin on breast cancer therapy.…”

Metformin and long non-coding RNAs in breast cancer

“…As GAS5 is associated with invasion, growth, tumor promotion, proliferation, and apoptosis of BC (Table 1 and Additional file 1 : Table S1), metformin can regulate these features by GAS5 antitumor activity. Metformin reverses EMT by inducing DNA methylation of the CpG-rich sequence at the gene downstream region in HOTAIR and downregulating the HOTAIR oncogenic expression in MDA-MB-231 BC cells [ 230 ]. The HOTAIR is associated with progression, metastasis, prognosis, cell growth, migration, invasion, apoptosis, and EMT in BC (Table 1 and Additional file 1 : Table S1), so metformin can regulate these features by changing HOTAIR expression.…”

Crosstalk between Methylation and ncRNAs in Breast Cancer: Therapeutic and Diagnostic Implications

“…Arsenic trioxide, metformin, and decitabine inhibit BC progression by modulating ncRNA promoter methylation [ 130 , 131 , 132 ] ( Table 4 ). Decitabine is a methyltransferase DNMT1 inhibitor that can be applied to various cancer therapies [ 133 ].…”