circ_103809 promotes breast cancer progression by regulating the PI3K/AKT signaling pathway

Abstract

Breast cancer is one of the most common cancer types in the world. This study was carried out to investigate the functional role of circular RNA circ_103809 in breast cancer. The expression of hsa_circ_103809 in breast cancer tissues and breast cancer cells were verified. After transfection, the expression of hsa_circ_103809 in the cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) and colony formation assay were used to detect cell proliferation. Apoptosis and cell cycle were detected by flow cytometry. AKT, p-AKT, BCL2 and Bax were detected by western blotting. Tumor formation assay was employd in vivo. The expression of circ_103809 in breast cancer was overexpressed. circ_103809 was proved to promote cell proliferation in breast cancer progression. In addition, circ_103809 was also involved in repressing cell apoptosis and accelerating cell cycle progression in vitro. circ_103809 accelerated breast cancer progression via regulating PI3K/AKT signaling. circ_103809 promoted tumor formation in vivo. The circular RNA hsa_circ_103809 was highly expressed in breast cancer tissues and cells, and may play an oncogene role in the development of breast cancer, and is expected to become a new target for breast cancer therapy.

Keywords: PI3K/AKT; apoptosis; breast cancer; circ_103809; proliferation.

Figure 1.

circ_103809 is upregulated in breast cancer. (A) Expression level of circ_103809 in breast cancer tissues and para-tumor tissues. (B) Analysis of circ_103809 expression level in breast cancer cell lines. (C) Transfection efficiency was evaluated by qRT-PCR. Data are presented as the mean ± SD of three independent experiments. **P<0.01; ***P<0.001; qRT-PCR, quantitative real-time polymerase chain reaction.

Figure 2.

Downregulated expression of circ_103809 suppresses cell proliferation and promotes cell apoptosis in breast cancer cell lines. (A) Cell proliferation ability was determined by CCK-8 assay. (B) Colony formation assay was employed for detecting cell proliferation. (C) Flow cytometric analysis was performed to detect the apoptotic rates in transfected cells. (D) Cell cycle progression was detected by flow cytometric analysis in transfected groups. Data are presented as the mean ± SD of three independent experiments. *P<0.05; **P<0.01; ***P<0.001; CCK-8, cell counting kit-8.

Figure 3.

The underlying mechanism of circ_103809 in breast cancer progression. (A) AKT, p-AKT expression levels were examined in transfected cell lines. (B) BCL2, Bax protein expression levels were examined in transfected cell lines. Data are presented as the mean ± SD of three independent experiments. *P<0.05; **P<0.01; ***P<0.001.

Figure 4.

Downregulated expression of circ_103809 inhibits tumor formation in vivo. (A) After tumor extraction, tumor volume was calculated, respectively and made into a graph. (B) The relative expression of circ_103809 in tumors were examined by qRT-PCR. Data are presented as the mean ± SD of three independent experiments. *P<0.05; **P<0.01; ***P<0.001.