Aberrant Methylation Of SPARC In Human Laryngeal And Hypopharyngeal Carcinoma

Objective:To explore the contribution of SPARC to the progression of laryngeal and hypopharyngeal carcinoma, we investigated transcription levels and promoter methylation of SPARC in cancer cell lines and primary tumors.Method:Reverse transcription-PCR (RT-PCR) was used to detect the expression of SPARC in laryngeal and hypopharyngeal carcinoma cell lines, laryngeal and hypopharyngeal carcinoma and normal epithelia specimens. Methylation status of SPARC in laryngeal carcinoma biopsies, hypopharyngeal carcinoma biopsies and normal epithelium were detected by methylation specific PCR (MSP) assay and bisulphite genomic sequencing (BGS). Pharmacological demethylation treatment rescued SPARC expression with 5-aza-2'-deoxycytidine in laryngeal carcinoma cell line. Correlation between methylation status of carcinoma and clinical data was analyzed by statistics.Results:SPARC expression was undetectable in laryngeal and hypopharyngeal carcinoma cell lines by RT-PCR, the transcription expression level of SPARC in methylated-tumor tissues was significantly lower than that of unmethylated-tumor (p<0.05), but no significant difference between primary tumors and normal epithelia. Hypermethylation of SPARC was detected in 56.1%(23/41) of laryngeal carcinoma and 70.0%(7/10) of hypopharyngeal carcinoma biopsies, but only 11.1%(1/9) of normal epithelia specimens. Bisulphite genomic sequencing (BGS) indicated CpG sites in SPARC promoter were heavily methylated in cell lines and primary tumors. Finally, SPARC promoter hypermethylation was significantly correlated with lymph node metastasis (p<0.01). Conclution:Hypermethylation of SPARC is a frequent and tumor-specific event in laryngeal and hypopharyngeal carcinoma and may serve as a biomolecular marker for diagnosis and prognosis.