Knockdown of lncRNA GHET1 inhibits osteosarcoma cells proliferation, invasion, migration and EMT in vitro and in vivo

Objective: Osteosarcoma is the most common primary malignant skeleton tumor that derives from mesenchymal cells. Emerging evidences have identified the vital role of long non-coding RNAs (lncRNAs) in the development of osteosarcoma. In this study, we aimed to investigate the role of lncRNA gastric carcinoma highly expressed transcript 1 (GHET1) in osteosarcoma progression.

Methods: The expression levels of relevant genes in clinical samples and cell lines were determined by quantitative real-time PCR. Cell proliferation was determined by CCK8 and cell colony formation assays. Transwell assay was used to detect the invasion and migration of osteosarcoma cells. Cell apoptosis and cell cycle were detected by flow cytometry. Protein levels were detected by western blot. In vivo tumor growth was investigated in the xenograft nude mice model. To determine whether growth inhibition and apoptosis are responsible for antitumor activity of silencing GHET1, immunohistochemistry for proliferation and TUNEL assay was performed in xenograft tissues. In vivo lung metastasis was performed to detect the effect of GHET1 on cell metastasis ability.

Results: Our results revealed that GHET1 was up-regulated in osteosarcoma tissues compared to normal tissues. GHET1 was also increased in osteosarcoma cell lines compared to normal osteoplastic cell line. The up-regulation of GHET1 was significantly associated with TNM stage, distant metastasis and lymph node metastasis in patients with osteosarcoma. In vitro studies showed that silencing GHET1 in MG-63 and U2OS cells inhibited cell proliferation, cell invasion and migration and epithelial-to-mesenchymal transition (EMT), promoted cell apoptotic rate, and also caused an increase in cell population at G0/G1 phase with a decrease in cell population at S phase. Overexpression of GHET1 promoted the proliferation, invasion and migration of osteosarcoma cells. Importantly, silencing GHET1 inhibited tumor growth and tumor metastasis in mice MG-63-xenograft model in association with changes of EMT-related genes, reduced expression of Ki-67 and promotion of apoptosis.

Conclusion: GHET1 was up-regulated in osteosarcoma tissues and cell lines, inhibited cell apoptosis, promoted cell proliferation, invasion and migration by affecting EMT in vitro, and was correlated with the tumor growth and metastasis in vivo. GHET1 may be a potential therapeutic target of osteosarcoma treatment.