Serum amyloid A promotes osteosarcoma invasion via upregulating αvβ3 integrin.

Serum amyloid A (SAA) is regarded as an important acute phase protein involved in tumor progression and metastasis. However, at present there is no evidence of its involvement in osteosarcoma. The present study aimed to investigate the effect of SAA on the invasion of osteosarcoma cells. The effects of SAA on the migration and invasion of osteosarcoma cells were detected using scratch wound healing and transwell assays, respectively. The expression of αvβ3 integrin was detected at the protein and mRNA levels in U2OS cells. Agonists, inhibitors or siRNA of formyl peptide receptor like‑1 (FPRL‑1), mitogen‑activated protein kinases and αvβ3 integrin were used to investigate the mechanism underlying the effects of SAA on the regulation of U2OS cell migration and invasion. The present study revealed that SAA promoted osteosarcoma cell migration and invasion. SAA upregulated the expression of αvβ3 integrin in a concentration‑ and time‑dependent manner. When inhibiting αvβ3 integrin with its antagonist, the migration and invasion abilities of the U2OS cells were markedly inhibited. SAA‑induced αvβ3 integrin production was significantly downregulated by inhibiting FPRL‑1 with siRNA and inhibitors. The present study also found that extracellular signal‑regulated kinase (ERK) 1/2, but not c‑Jun N‑terminal kinase or p38, was important in this process. These findings demonstrated that SAA regulated osteosarcoma cell migration and invasion via the FPRL‑1/ERK/αvβ3 integrin pathway.