Correlation Between Expression of SIX1, TGF-β and VEGF-C in Primarily Cultured Human Laryngeal Squamous Cell Carcinoma Cells

Objective  To investigate the relationship between sine oculis homeobox homolog 1(SIX1) , TGF-β and VEGF-C in primarily cultured human laryngeal squamous cell carcinoma cells.

Methods  We took fresh human laryngeal squamous cell carcinoma tissues and cultured the primary cells. The technology of RNA interference was used for preparing SIX1-targeting, TGF-β-targeting and SIX1+TGF-β-targeting siRNA to transfect laryngeal squamous cell carcinoma cells. After successful transfection, the experiments were divided into five groups: Group A (untransfected), Group B(empty vector), Group C(SIX1-siRNA), Group D(TGF-β-siRNA) and Group E(SIX1+TGF-β-siRNA). The protein expression of SIX1, TGF-β and VEGF-C were determined by immunohistochemistry and Western blot. The mRNA levels of SIX1, TGF-β and VEGF-C were determined by RT-PCR.

Results  The protein and mRNA expression of SIX1, TGF-β and VEGF-C in empty vector group had no significant difference compared with untransfected group. In SIX1- siRNA group, the expression of SIX1 protein and mRNA were decreased, at the same time the expression of VEGF-C was decreased, with statistically significant difference compared with untransfected group. In TGF- β-siRNA group, the expression of TGF-β protein and mRNA were decreased, at the same time the expression of VEGF-C was decreased, with statistically significant difference compared with untransfected group. Compared with SIX1-siRNA and TGF-β-siRNA groups, the expression of VEGF-C protein and mRNA had no significant decrease in SIX1+TGF-β-siRNA group.

Conclusion  SIX1 could promote lymph node metastasis by coordinating with TGF-β to increase the expression of VEGF-C protein and mRNA, suggesting that SIX1 and TGF-β might be potential therapeutic targets for preventing lymph node metastasis from human laryngeal squamous cell carcinoma.