Knockdown of TBRG4 suppresses proliferation, invasion and promotes apoptosis of osteosarcoma cells by downregulating TGF-β1 expression and PI3K/AKT signaling pathway.

Transforming growth factor beta regulator 4 (TBRG4) is a novel regulator in tumorigenic progression of several tumors. However, so far, the expression and functions of TBRG4 in osteosarcoma are unknown. The aim of this study was to investigate the potential biological functions of TBRG4 in osteosarcoma. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of TBRG4 in osteosarcoma tissues and cell lines. The levels of TBRG4 protein in osteosarcoma tissues were assessed by immunohistochemistry. Lentivirus-mediated short hairpin (sh) RNA was employed to knock down TBRG4 in osteosarcoma cells, and the expressions of TBRG4 mRNA and protein were determined by qRT-PCR and Western blot assay, respectively. Subsequently, the proliferation, clonogenic ability, apoptosis and invasion of osteosarcoma cells were measured using high content screening analysis and CCK8 assay, tumor sphere formation assay, flow cytometry and Transwell invasion assays, respectively. Furthermore, the osteosarcoma cells growth and metastasis in vivo were detected, and the effect of TBRG4 on the transforming growth factor β1 (TGF-β1) and PI3K/AKT signaling pathway was explored by qRT-PCR and Western blot assay, respectively. The results showed the levels of TBRG4 were overexpressed in osteosarcoma tissues and cell lines, confirming that the high TBRG4 expression was related to advanced tumor stages, large tumor size, and lymph node metastasis. Functional assays showed knockdown of TBRG4 could inhibit proliferation, invasion and induce apoptosis of osteosarcoma cells in vitro, and could also suppress osteosarcoma growth and metastasis in vivo. By examining the expression levels of TGF-β1, p-PI3K, PI3K, p-AKT and AKT, it showed that the suppression of TBRG4 would reduce TGF-β1 expression and inactivate the PI3K/AKT signaling pathway. These results showed for the first time that TBRG4 knockdown could suppress osteosarcoma progression, suggesting TBRG4 might be a promising therapeutic target for osteosarcoma treatment.

Huang F ，Zhou P ，Wang Z ，Zhang XL ，Liao FX ，Hu Y ，Chang J ... -  《-》

Downregulation of long non-coding RNA DBH-AS1 inhibits osteosarcoma progression by PI3K-AKT signaling pathways and indicates good prognosis.

Liu ZB ，Wang JA ，Lv RQ 《-》

SIX1 reduces the expression of PTEN via activating PI3K/AKT signal to promote cell proliferation and tumorigenesis in osteosarcoma.

Osteosarcoma is the most common form of primary malignant bone cancer which is most prevalent in children and adolescents. Dysregulated expressions of SIX1 and PTEN/PI3K/AKT have been demonstrated in bone malignancies including osteosarcoma. However, the mechanism of SIX1/PTEN/PI3K/AKT on osteosarcoma progression remains unknown. Therefore, this study aims to investigate the molecular mechanism of SIX1 and PTEN/PI3K/AKT on osteosarcoma progression. In this study, we first examined the expression of SIX1 and PTEN in human osteosarcoma tissues or blood samples and cell lines by immunohistochemistry, western blot analysis and qPCR. MTT, clone formation assay, wound healing assay, Transwell assay, in vivo tumorigenesis, flow cytometry and western blot were used to determine the function of SIX1/PTEN on cell proliferation, clone formation ability, migration, invasion, tumorigenesis, and cell apoptosis in SAOS2 and U2OS cells, respectively. Results showed that SIX1 was overexpressed in osteosarcoma tissues, blood samples and cell lines, whereas PTEN expression was reduced. SIX1 promoted cell growth, migration, invasion, and suppressed cell apoptosis. Up-regulation of SIX1 associated with reduced expression of PTEN and activation of PI3K/AKT signaling pathway. Down-regulated the expression of PTEN using gene transfer in U2OS and SAOS2 cells increased cell proliferation and inhibited cell apoptosis through activating PI3K/AKT signaling cascade. In addition, the tumorigenesis of U2OS and SAOS2 cells was suppressed when the cells were stably overexpressed SIX1 and PTEN simultaneously, compared with that in cells stably overexpressed SIX1 only. SIX1 promoted the progression of osteosarcoma via regulating PTEN/PI3K/AKT signaling cascade, which might provide a new potent therapeutic target for osteosarcoma.

Yu C ，Zhang B ，Li YL ，Yu XR ... -  《-》

LncRNA LINC00628 overexpression inhibits the growth and invasion through regulating PI3K/Akt signaling pathway in osteosarcoma.

He R ，Wu JX ，Zhang Y ，Che H ，Yang L ... -  《-》

BTG2 inhibits the proliferation and metastasis of osteosarcoma cells by suppressing the PI3K/AKT pathway.

Li YJ ，Dong BK ，Fan M ，Jiang WX ... -  《International Journal of Clinical and Experimental Pathology》