Vasodilator-stimulated phosphoprotein regulates osteosarcoma cell migration

Abstract

Abstract. Vasodilator-stimulated phosphoprotein (VASP) has been reported to play an important role in the process of cell migration and tumor metastasis. However, to date, no study has examined VASP expression and its function in osteocarcoma cells. In this study, we analyzed the effect of VASP on osteosarcoma cell migration and the signal transduction pathways involved. We used two osteosarcoma cell strains (Mg-63 and Saos-2 cells) with different metastatic potential. Silencing of VASP gene expression was carried out using RNA interference in these cells. Knockdown of expression at the transcriptional or translational level was determined by RT-PCR or Western blot analysis, respectively. The metastatic potential of the tumor cells was determined by a wound healing migration assay. VASP mRNA expression was also determined in 30 human osteosarcoma samples. Furthermore, Rac1 was determined as a regulator of VASP function. RT-PCR and Western blotting showed that Mg-63 cells had a significantly higher VASP expression at both the transcriptional and translational levels compared to Saos-2 cells. The wound healing assay revealed that Mg-63 cells had more migratory potential compared to Saos-2 cells. The effect was found to be reversible when VASP was knocked down by siRNA in Mg-63 cells. Specimens from human patients with metastases had higher VASP expression compared to specimens of patients without metastases. Knockdown of Rac1 resulted in inhibition of VASP expression in sarcoma cells. These results suggest that VASP protein regulates osteosarcoma cell migration and metastasis. Rac1 and VASP interaction may be a potential target for osteosarcoma treatment. IntroductionOsteosarcoma is the most prevalent primary malignant bone tumor in children and young adults. Although the life expectancy of osteosarcoma patients has been prolonged due to improvement of neoadjuvant chemotherapy and surgical resection during the past three decades, the long-term survival and quality of life is still unsatisfactory. Poor outcome of osteosarcoma is mainly caused by metastatic disease, and previous studies have demonstrated that more than 30% of patients already display distant metastasis without clinical detectable signs at the time of diagnosis (1,2).Vasodilator-stimulated phosphoprotein (VASP), a member of the Ena/VASP family, has been implicated in regulating key cellular functions, such as shape change, adhesion and migration, which is mainly due to its ability to modify dynamic action cytoskeleton (3). In addition to its role in normal cell growth (4,5), embryonic development (6) and homeostasis (7), VASP plays an essential role in many diseases, such as cancer metastasis (8,9), thrombosis (10), arteriosclerosis (11) and nephritis (12).Expression of VASP has been reported to be dysregulated in several types of malignancies and is relevant to tumor metastasis. For example, its level was found to be significantly increased in lung adenocarcinomas and gastric carcinomas compared to normal tissue, and this increase was correlated wit...

Knockdown of RAC1 and VASP gene expression inhibits breast cancer cell migration

“…The intensity of Mena expression increases from premalignant to malignant lesions in various organs, including the large bowel, stomach, cervix and salivary glands ( 8 , 32 ). Aggressive and migratory Mg-63 osteosarcoma cells contain comparatively higher expression levels of VASP at the transcriptional and translational levels, compared with the less aggressive Saos-2 osteosarcoma cells ( 33 ). Overexpression of VASP in wild-type NIH 3T3 cells results in metaplasia to cancer cells ( 34 ), and the increased expression level of VASP in lung adenocarcinoma correlates with lower cellular differentiation and an increased pathological stage of the tumor ( 8 ).…”

Role of vasodilator‑stimulated phosphoprotein in human cytomegalovirus‑induced hyperpermeability of human endothelial cells

“…These results indicated that HCMV-induced endothelium hyperpermeability may be mediated by Rac1 and VASP-associated cell-cell junction remodeling. In addition, as VASP is a downstream effector of Rac1 in osteosarcoma cells, interference of Rac1 in the cells led to a significant reduction in VASP expression ( 21 ). Additionally, consistent with previous reports, the EC data from the current study also revealed that interfering with the expression of Rac1 using siRNA-Rac1 could inhibit the expression of VASP.…”

“…In addition, Rac1 regulates the alterations of endothelial permeability by mediating skeletal protein remodeling ( 20 ). It has been demonstrated that VASP is a downstream effector of Rac1 in osteosarcoma cells ( 21 ). Therefore, Rac1-mediated VASP activation may be involved in maintaining the barrier function of ECs.…”

The Role of Vasodilator-stimulated Phosphoproteins in the Development of Malignant Tumors

“…Nayak et al [ 59 ] demonstrated that the level of phosphorylated VASP (Ser239) is upregulated by knocking down lysosome-associated membrane protein 3, thereby weakening the aggressiveness and metastasis of esophageal squamous cell carcinoma cells. Wu et al [ 60 ] suggested that Rac1 knockdown leads to VASP expression in osteosarcoma cells, attenuating their migration and metastasis. Li et al [ 61 ] showed that circRFX3 promoted glioma progression by regulating the miR-1179/miR-1229-VASP axis.…”