S100A4 silencing suppresses proliferation, angiogenesis and invasion of thyroid cancer cells through downregulation of MMP-9 and VEGF

W. Jia, X.-j. Gao, Z.-d. Zhang, Z.-x. Yang, G. Zhang

Department of Hepatobiliary and Pancreatic Surgery, Huaxi Hispital Sichuan University, Chengdu, Sichuan, China. scdxhxyy28@126.com

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• Oncology

BACKGROUND AND AIM: It is well documented that S100A4 is upregulated in many cancers and plays a pivotal role in tumor proliferation, invasion, metastasis and angiogenesis. However, the precise role and mechanism S100A4 exerts in the thyroid cancer have not been fully elucidated to date. In the present study, we investigated the effect of S100A4 on proliferation, invasion, metastasis and angiogenesis in thyroid cancer cells.

MATERIALS AND METHODS: A plasmid construct was made that expressed full long S100A4 cDNA. The construct was stably transfected into BCPAP and ML-1 thyroid cancer cells (BCPAP/ S100A4 cDNA, ML-1/S100A4 cDNA). S100A4 siRNA was transiently transfected into the DRO cells (DRO/S100A4 siRNA). MMP-9 siRNA or VEGF siRNA was transiently transfected into the BCPAP/ S100A4 cDNA, ML-1/S100A4 cDNA cells (BCPAP/ S100A4 cDNA/VEGF siRNA, ML-1/S100A4 cDNA/ MMP-9 siRNA).

RESULTS: We found that the down-regulation of S100A4 by small interfering RNA decreased cell invasion, metastasis, and angiogenesis by using chicken chorioallantoic membrane (CAM), whereas S100A4 overexpression by cDNA transfection led to increased tumor cell invasion, metastasis, and angiogenesis. Consistent with these results, we found that the down-regulation of S100A4 reduced VEGF and MMP-9 expression. Furthermore, Knockdown of MMP-9 by MMP-9 siRNA inhibited cell invasion and metastasis in the BCPAP/S100A4 cDNA, ML-1/S100A4 cDNA cells. Knockdown of VEGF by VEGF siRNA inhibited cell angiogenesis in the BCPAP/ S100A4 cDNA, ML-1/S100A4 cDNA cells.We also found that downregulation of S100A4 by small interfering RNA resulted in enhanced cell growth inhibition and apoptosis, and vice versa. Our data suggest S100A4 could be an effective approach for the regulation of proliferation, invasion and angiogenesis. Downregulation of S100A4 could inhibit angiogenesis, proliferation and invasion by regulating the expression of MMP-9 and VEGF.

CONCLUSIONS: Our results provide evidence that the downregulation of S100A4 using RNAi technology may provide an effective tool for thyroid cancer therapy.

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