He Qian, Wei Jiazhang, Zhang Jinyan, Jiang Heng, Wang Shumin, Zhou Xiaoying, Zhang Zhe, Huang Guangwu, Watanabe Hiroshi, Su Jiping
Department of Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, P.R. China.
Oncol Lett. 2011 Jul;2(4):725-729. doi: 10.3892/ol.2011.297. Epub 2011 May 5.
Secreted protein, acidic and rich in cysteine (SPARC) has been found to be involved in various stages of tumor progression such as migration, invasion, extracellular matrix deposition and angiogenesis. To obtain an insight into the role of SPARC in the progression of laryngeal and hypopharyngeal carcinoma, we investigated SPARC transcription levels and promoter methylation in carcinoma cell lines and primary tumors. Reverse transcription-PCR showed that SPARC was silenced in laryngeal and hypopharyngeal carcinoma cell lines, in which aberrant promoter methylation was detected. Hypermethylation of SPARC was detected in 56.1% (23/41) of laryngeal carcinoma and 70.0% (7/10) of hypopharyngeal carcinoma biopsies, but only in 11.1% (1/9) of normal epithelial specimens by a methylation-specific PCR assay. Bisulphite genomic sequencing indicated that CpG sites in the SPARC promoter were heavily methylated in cell lines and primary tumors. Moreover, pharmacological demethylation treatment rescued SPARC expression with 5-aza-2'-deoxycytidine (5-aza-dC) in the laryngeal carcinoma cell lines. SPARC promoter hypermethylation was significantly correlated with lymph node metastasis (p<0.01). Our findings suggest that hypermethylation of SPARC is a frequent and tumor-specific event in laryngeal and hypopharyngeal carcinomas and may serve as a biomolecular marker for diagnosis and prognosis.
分泌性蛋白质，富含酸性和半胱氨酸（SPARC）已被发现参与肿瘤进展的各个阶段，如迁移、侵袭、细胞外基质沉积和血管生成。为了深入了解SPARC在喉癌和下咽癌进展中的作用，我们研究了癌细胞系和原发性肿瘤中SPARC的转录水平及启动子甲基化情况。逆转录聚合酶链反应显示，SPARC在喉癌和下咽癌细胞系中沉默，且检测到异常的启动子甲基化。通过甲基化特异性聚合酶链反应检测发现，56.1%（23/41）的喉癌活检组织和70.0%（7/10）的下咽癌活检组织中存在SPARC的高甲基化，但正常上皮标本中仅11.1%（1/9）出现。亚硫酸氢盐基因组测序表明，SPARC启动子中的CpG位点在细胞系和原发性肿瘤中高度甲基化。此外，用5-氮杂-2'-脱氧胞苷（5-aza-dC）对喉癌细胞系进行药物去甲基化处理可恢复SPARC的表达。SPARC启动子高甲基化与淋巴结转移显著相关（p<0.01）。我们的研究结果表明，SPARC的高甲基化在喉癌和下咽癌中是常见且具有肿瘤特异性的事件，可能作为诊断和预后的生物分子标志物。
