Evaluation of Boric Acid Treatment on microRNA-127-5p and Metastasis Genes Orchestration of Breast Cancer Stem Cells

Abstract

Coregulation of microRNAs (miRNAs) and cancer stem cells (CSCs) is very important in carcinogenesis. miR-127-5p is known to be downregulated in breast cancer. In this study, we aimed to investigate how boric acid (BA), known for its previously unstudied anti-cancer properties, would affect the expression of miR127-5p and genes responsible for breast cancer stem cells (BC-SCs) metastasis. BC-SCs were isolated from human breast cancer cells (MCF-7) by immunomagnetic cell separation and characterized with flow cytometry and sphere formation. The viability of BC-SCs and the determination of its IC50 value in response to boric acid (BA) were assessed via the MTT assay. Boric acid exhibited dose- and time-dependent inhibition of cell viability in cells. The IC50 doses of boric acid in MCF-7 cells and BC-SCs were 45.69 mM and 41.27 mM, respectively. The impact of BA on the expression of metastatic genes and miR127-5p was elucidated through RT-qPCR analysis. While the expression of the COL1A1 (p < 0.05) and VIM (p < 0.01) was downregulated, the expression of the miR-127-5p, ZEB1 (p < 0.01), CDH1 (p < 0.05), ITGB1 (p < 0.05), ITGA5 (p < 0.05), LAMA5 (p < 0.01), and SNAIL (p < 0.05), was up-regulated in dose-treated BC-SCs (p < 0.001) to the RT-qPCR results. Our findings suggest that boric acid could induce miR-127-5p expression. However, it cannot be said that it improves the metastasis properties of breast cancer stem cells.

Keywords: Boric acid; Breast cancer; Cancer stem cell; Metastasis; miR-127-5p.

Fig. 1

Morphology of MCF-7 cells and BC-SCs as viewed under an inverted microscope. A MCF-7 cells. B Formation of cell spheres by BC-SCs in serum-free medium (scale bar = 200 µm)

Fig. 2

BC-SCs exhibited an enhanced capacity for sphere formation (scale bar = 100 µM)

Fig. 3

Flow cytometry analysis revealed the presence of BC-SCs. A CD326+ B CD117+/CD133+ C CD44+ D ABCG2 + cell populations on the surface of BC-SCs

Fig. 4

Impact of boric acid on cancer stem cell proliferation. Cells were cultured in a medium with varying concentrations of boric acid (0–100 mM), and cell viability was assessed using the MTT assay after 48 h. Data are presented as the mean ± standard deviation from three independent experiments (mean ± SD, n = 3). Statistical significance was denoted as *p < 0.05, **p < 0.01, and ***p < 0.001, while “ns” indicates no significant difference

Fig. 5

Expression profile of miR-127-5p and metastasis genes. In dose-treated BC-SCs, VIM and COL1A1 expression was significantly downregulated. Conversely, the expression levels of miR-127-5p, CDH1, ITGB1, ITGA5, ZEB1, SNAIL, and LAMA5 were notably up-regulated (mean ± SD, n = 3, *p < 0.05, **p < 0.01, and ***p < 0.001, with “ns” indicating no significant difference)