Abstract
Tripartite motif-containing 44 (TRIM44) was reported to be involved in the tumorigenesis of several tumors, but its function in laryngeal squamous cell carcinoma has not been investigated yet. In the present study, we aimed to elucidate the function of TRIM44 in laryngeal squamous cell carcinoma, and identify the compounds which could inhibit TRIM44 expression. Our results showed that TRIM44 was upregulated in tumor tissues and cell lines of laryngeal squamous cell carcinoma. Knockdown of TRIM44 significantly inhibited cell growth of laryngeal squamous cell carcinoma by suppressing TLR4, phosphorylated AKT and phosphorylated NF-κB p65 expression in vitro. Moreover, TRIM44 knockdown inhibited tumor growth in nude mice, which further suggested that TRIM44 exerted oncogenic activity in laryngeal squamous cell carcinoma. Interestingly, it was found that nuciferine significantly inhibited the mRNA levels of TRIM44 after screening a small natural compound library. Our further studies showed nuciferine markedly downregulated the protein levels of TRIM44 and its substrate TLR4 in a concentration-dependent manner in laryngeal squamous cell carcinoma cells. Moreover, the activation of downstream kinases of TLR4 such as AKT signaling pathway was also inhibited by nuciferine. Additionally, nuciferine markedly inhibited cell survival of laryngeal squamous cell carcinoma in a concentration-dependent manner. In contrast, TRIM44 overexpression significantly reduced the cytotoxicity of nuciferine in laryngeal squamous cell carcinoma cells. In conclusion, this study indicated that inhibiting TRIM44 would be a useful strategy for the treatment of laryngeal squamous cell carcinoma, and nuciferine could be a potential chemical applicated in the therapy of laryngeal squamous cell carcinoma.