MicroRNA‑125a‑5p controls the proliferation, apoptosis, migration and PTEN/MEK1/2/ERK1/2 signaling pathway in MCF‑7 breast cancer cells

Abstract

MicroRNA (miR)‑125a‑5p has shown the potential for suppressing tumorigenesis and development; however, the effects of miR‑125a‑5p on breast cancer cells remains unknown. The aim of this study was to evaluate the effects and underlying mechanisms of miR‑125a‑5p in MCF‑7 breast cancer cells. MCF‑7 cells were transfected with miR‑125a‑5p mimic or miR‑125a‑5p small interfering RNA to produce miR‑125a‑5p overexpressing/knockdown cells. Cell proliferation was assessed by an MTT assay, and cell migration ability was determined by an in vitro scratch assay. Hoechst 33258 staining and flow cytometry were performed to assess the effects of miR‑125a‑5p on MCF‑7 apoptosis. Western blotting and reverse transcription‑quantitative polymerase chain reaction were used for measuring phosphatase and tensin homolog (PTEN), phosphorylated (p)‑mitogen‑activated protein kinase kinase (MEK1/2)/MEK1/2, p‑ERK1/2/ERK1/2, B‑cell lymphoma‑2 (Bcl‑2), cleaved caspase‑3, and miR‑125a‑5p expression. miR‑125a‑5p overexpression inhibited the proliferation and migration, but promoted the apoptosis of MCF‑7 cells. These effects were associated with increases in PTEN and cleaved caspase‑3 expression, and decreases in p‑MEK1/2/MEK1/2, p‑ERK1/2/ERK1/2, and Bcl‑2. Silencing of miR‑125a‑5p exhibited opposing effects on MCF‑7 cells. These observations suggested that miR‑125a‑5p participates in the regulation of multiple functions of MCF‑7 cells by promoting the expression of PTEN tumor suppressor genes, activating MEK1/2/ERK1/2 signaling, and regulating caspase‑3/Bcl‑2 signaling. Thus, it may be a suitable target for breast cancer gene therapy.

Figure 1.

Overexpression and knockdown of miR-125a-5p in MCF-7 cells. (A) miR-125a-5p overexpression, silencing and control cells were observed by fluorescence microscopy. Scale bar=400 µm. (B) Reverse transcription-quantitative polymerase chain reaction demonstrated the levels of miR-125a-5p in MCF-7 cells. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. Lv, lentiviral; miR, microRNA; NC, negative control.

Figure 2.

Effects of miR-125a-5p overexpression and silencing on MCF-7 cell proliferation. Proliferation ability of MCF-7 cells between the miR-125a-5p overexpression, silencing and control groups. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. Lv, lentiviral; miR, microRNA; NC, negative control.

Figure 3.

Effects of miR-125a-5p overexpression and silencing on the migration of MCF-7 cells. (A) Migration ability of MCF-7 cells in the miR-125a-5p overexpression, silencing and control groups. Scale bar=400 µm. (B) Summarized data of the migration of MCF-7. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. Lv, lentiviral; miR, microRNA; NC, negative control.

Figure 4.

Effects of miR-125a-5p on PTEN, p-MEK1/2/MEK1/2, and p-ERK1/2/ERK1/2 expression in MCF-7 cells. (A) Expression of PTEN, p-MEK1/2/MEK1/2, and p-ERK1/2/ERK1/2 in MCF-7 cells. (B) Summarized data of the PTEN expression. (C) Summarized data of the p-MEK1/2/MEK1/2 level. (D) Summarized data of the p-ERK1/2/ERK1/2 level. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. ERK, extracellular signal-regulated kinase; Lv, lentiviral; MEK, mitogen-activated protein kinase kinase; miR, microRNA; NC, negative control; p, phosphorylated; PTEN, phosphatase and tensin homolog.

Figure 5.

Effects of miR-125a-5p on serum deprivation-induced apoptosis of MCF-7 cells. (A and B) Representative images and summarized data of MCF-7 apoptosis as detected by flow cytometry. (C and D) Representative images and summarized data of MCF-7 apoptosis as detected by Hoechst 33258 staining. Scale bar=100 µm. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. 7-AAD, 7-amino-actinomycin; Lv, lentiviral; miR, microRNA; NC, negative control; PE, phycoerythrin.

Figure 6.

Effects of miR-125a-5p on cleaved caspase-3 and Bcl-2 expression in MCF-7 cells. (A) Expression of cleaved caspase-3 and Bcl-2 in MCF-7 cells. (B) Summarized data of the cleaved caspase-3 expression. (C) Summarized data of the Bcl-2 level. *P<0.05, vs. MCF-7^NC; ⁺P<0.05, vs. MCF-7^miR-125a-5p; n=6/group. Bcl-2, B-cell lymphoma-2; Lv, lentiviral; miR, microRNA; NC, negative control.