COPB2 as a key regulator of cell growth in human osteosarcoma cells: Potential therapeutic target and prognostic indicator.

PURPOSE

Coatomer protein complex subunit beta 2 (COPB2) is a crucial component of the coatomer protein complex I, responsible for vesicle transport. Previous studies have indicated that COPB2 is highly expressed in malignant tumors and is involved in cell proliferation and apoptosis. However, the role of COPB2 in osteosarcoma and its underlying mechanisms remain unclear. This study aimed to investigate the impact of COPB2 on proliferation, apoptosis, and colony formation in human osteosarcoma cells, as well as to explore potential mechanisms.

METHODS

Kaplan-Meier survival analysis was conducted to assess the association between COPB2 expression and the prognosis of osteosarcoma patients using data extracted from the Cancer Genome Atlas (TCGA) database. Additionally, COPB2 expression was examined in osteosarcoma tissue samples and four osteosarcoma cell lines using immunohistochemistry and quantitative real-time PCR (qRT-PCR). COPB2 expression was downregulated using siRNA in U2OS and SAOS-2 human osteosarcoma cells. Cell proliferation and colony formation were assessed using Cellomics/Celigo and Giemsa staining, respectively. Flow cytometry was used to evaluate cell cycle distribution and apoptosis. Tumor growth was evaluated in vivo model. Furthermore, the regulation mechanism of COPB2 on osteosarcoma cells was investigated using the Human Phospho-Kinase Array Kit.

RESULTS

Patients with high COPB2 expression exhibited shorter overall survival and disease-free survival compared to those with low COPB2 expression. COPB2 was found to be highly expressed in osteosarcoma tissue samples and cell lines. Silencing of COPB2 significantly inhibited cell proliferation and colony formation. Additionally, COPB2 silencing altered the cell cycle distribution, leading to cell cycle arrest in the G2 phase, and promoted cell apoptosis in osteosarcoma cells. Further investigations revealed that COPB2 silencing inhibited tumor growth and lung metastases of osteosarcoma cells in vivo, and its effects on cell proliferation and apoptosis may be mediated through the regulation of kinase phosphorylation levels.

CONCLUSIONS

COPB2 expression is increased in osteosarcoma cells and plays a crucial role in cell growth regulation. Silencing of COPB2 inhibits cell proliferation, colony formation, and promotes cell apoptosis. Furthermore, COPB2 silencing inhibits tumor growth in vivo, suggesting its potential as an important therapeutic target in treating osteosarcoma.