Full-length spleen tyrosine kinase inhibits the invasion and metastasis of human laryngeal squamous cell carcinoma.

Objective: This study aimed to investigate correlation between full-length spleen tyrosine kinase [SYK (L)] expression and clinical characteristics of laryngeal squamous cell carcinoma (LSCC), and explore effects of SYK (L) on invasion and metastasis of LSCC. Methods: The human laryngeal cancer Hep-2 cells with low SYK (L) expression were transfected with pIRES2-EGFP-SYK (L) vector and empty vector pIRES2-EGFP to generate Hep-2-SYK (L) cells and Hep-2-neo cells. The cell invasion and migration abilities were determined. Results: The SYK (L) positive expression rate in LSCC tissues was significantly lower than in vocal cord dysplasia tissues and normal laryngeal tissues (P < 0.05). There was a significant correlation between SYK (L) expression and LSCC T stage, histopathological grade and lymph node metastasis (P < 0.05). mRNA expression of SYK (L) in Hep-2-SYK (L) cells was significantly higher than in Hep-2-neo cells and Hep-2 cells (P < 0.01). The protein expression of SYK (L) in Hep-2-SYK (L) cells was markedly higher than in Hep-2-neo cells and Hep-2 cells (P < 0.01). The number of invasive cells was significantly lower in Hep-2-SYK (L) group than in Hep-2-neo group and Hep-2 group (P < 0.01). The average number of migrating cells in Hep-2-SYK (L) group also markedly reduced as compared to Hep-2-neo group and Hep-2 group (P < 0.01). Conclusion: The SYK (L) expression was down-regulated in LSCC, which was closely correlated with cancer growth and lymph node metastasis. SYK (L) up-regulation was able to inhibit the invasion and metastasis of LSCC, therefore suppressing tumor development. Thus, SYK (L) may be a potential target for the LSCC treatment.