Abstract: Objective  To explore the expression of Klotho gene in human laryngeal carcinoma tissues and its clinical significance. Methods The expression of Klotho mRNA and protein were measured in 80 paired normal and laryngeal squamous cell carcinoma （LSCC） tissue samples by real-time fluoresence quntitative polymerase chain reaction（QPCR） and Western blotting. The relation between Klotho expression and clinical pathological parameters was investigated. Methylation-specific polymerase（MSP） chain reaction were performed to analyze the DNA methylation of Klotho promoter. Results The expression of Klotho mRNA in LSCC tissues was 0.2890±0.012， significantly lower than 0.7908±0.015 in corresponding non-malignant tissues（P＜0.01）. The expression of Klotho protein in LSCC tissues was 0.2290±0.009， significantly lower than 0.5368±0.023 in their corresponding non-tumor tissues（P＜0.01）. The expression of Klotho was related to depth of tumor invasion and lymph node metastasis， but not related to age， sex， tumor location and degree of differentiation （P＞0.05）. The DNA methylation rate of Klotho gene promoter region in 80 cases of LSCC and adjacent non-tumor laryngeal tissues was 53.8％ （43／80） and 26.2％ （21／80）， respectively， and the difference was statistically significant （P＜0.05）. Conclusion  The aberrant DNA methylation of Klotho promoter region may be mainly responsible for its down-regulation in LSCC， and plays a key role in invasion and metastasis.

Key words: Laryngeal squamous cell carcinoma （LSCC）, Klotho gene, DNA methylation