Armadillo Repeat-Containing Protein 8 (ARMC8) Silencing Inhibits Proliferation and Invasion in Osteosarcoma Cells

Abstract

Armadillo repeat-containing protein 8 (ARMC8) plays an important role in regulating cell migration, proliferation, tissue maintenance, signal transduction, and tumorigenesis. However, the expression pattern and role of ARMC8 in osteosarcoma are still unclear. In this study, our aims were to examine the effects of ARMC8 on osteosarcoma and to explore its underlying mechanism. Our results demonstrated that ARMC8 was overexpressed in osteosarcoma cell lines. Knockdown of ARMC8 significantly inhibited osteosarcoma cell proliferation in vitro and markedly inhibited xenograft tumor growth in vivo. ARMC8 silencing also suppressed the epithelial-mesenchymal transition (EMT) phenotype, as well as inhibited the migration and invasion of osteosarcoma cells. Furthermore, knockdown of ARMC8 obviously inhibited the expression of β-catenin, c-Myc, and cyclin D1 in MG-63 cells. In conclusion, this report demonstrates that ARMC8 silencing inhibits proliferation and invasion of osteosarcoma cells. Therefore, ARMC8 may play an important role in the development and progression of human osteosarcoma and may represent a novel therapeutic target in the treatment of osteosarcoma.

Figure 1

Armadillo repeat-containing protein 8 (ARMC8) is overexpressed in human osteosarcoma cell lines. (A) Representative mRNA expression of ARMC8 in human osteosarcoma cell lines. (B) Representative Western blot image of ARMC8 protein in human osteosarcoma cells lines. Data represent mean ± SD from three independent experiments. *p < 0.05.

Figure 2

ARMC8 silencing inhibits osteosarcoma cell proliferation in vitro. (A) mRNA and protein levels of ARMC8 in ARMC8-shRNA-transfected MG-63 cells. (B) mRNA and protein levels of ARMC8 in ARMC8-shRNA-transfected U2OS cells. (C) Knockdown of ARMC8 inhibited the proliferation of MG-63 cells in a time-dependent manner. (D) Knockdown of ARMC8 inhibited the proliferation of U2OS cells in a time-dependent manner. Data represent mean ± SD from three independent experiments. *p < 0.05.

Figure 3

ARMC8 silencing inhibits the growth of osteosarcoma in vivo. MG-63 cells (1 × 10⁶ cells/0.1 ml) transfected with ARMC8-shRNA or scr-shRNA were injected subcutaneously into the flank of nude mice. (A) The tumor volumes were calculated in each group every 7 days from day 0 to day 35. (B) The tumor weights were measured at day 35. Data represent mean ± SD. *p < 0.05.

Figure 4

ARMC8 silencing inhibits the EMT process in osteosarcoma cells. MG-63 or U2OS cells were transfected with ARMC8-shRNA or scr-shRNA for 24 h. (A) The protein expression levels of E-cadherin and N-cadherin were detected by Western blot in MG-63 cells and quantification of protein levels from three independent experiments. (B) The protein expression levels of E-cadherin and N-cadherin were measured by Western blot in U2OS cells and quantification of protein levels from three independent experiments. Data represent mean ± SD. *p < 0.05.

Figure 5

ARMC8 silencing inhibits OS cell migration and invasion in vitro. MG-63 or U2OS cells were transfected with ARMC8-shRNA or scr-shRNA for 24 h. (A) The number of migrated/invaded cells in the ARMC8-shRNA-transfected MG-63 cells was obviously decreased, compared with the scr-shRNA group. (B) Knockdown of ARMC8 significantly inhibited the migration and invasion of U2OS cells. Data represent mean ± SD from three independent experiments. *p < 0.05.

Figure 6

ARMC8 silencing inhibits the activation of Wnt/β-catenin signaling pathway in OS cells. (A) MG-63 cells were transfected with ARMC8-shRNA or scr-shRNA for 24 h. The protein expression of β-catenin, cyclin D1, and c-Myc was detected by Western blot. (B) Relative expression of β-catenin, cyclin D1, and c-Myc was quantified using Image-Pro Plus 6.0 software after normalization with β-actin. Data represent mean ± SD from three independent experiments. *p < 0.05.